CN113772800B

CN113772800B - Method for adding carbonic acid by adopting small carbonic acid solution adding system

Info

Publication number: CN113772800B
Application number: CN202111137269.0A
Authority: CN
Inventors: 林峡
Original assignee: Harvey Shanghai Environmental Technology Co ltd
Current assignee: Harvey Shanghai Environmental Technology Co ltd
Priority date: 2021-09-27
Filing date: 2021-09-27
Publication date: 2024-01-09
Anticipated expiration: 2041-09-27
Also published as: CN113772800A

Abstract

The invention discloses a method for adding carbonic acid by adopting a small carbonic acid solution adding system. The method comprises the steps of 1) establishing a small carbonic acid solution adding system, wherein the small carbonic acid solution adding system comprises a reaction tank, a diffuser, a carbon dioxide gas pipeline, a reaction water pipeline and a water pump; a water mist nozzle and a carbon dioxide gas nozzle are arranged on the top of the inner tank of the reaction tank; a control valve is arranged between the reaction tank and the diffuser; the diffuser is arranged in the water to be treated; the side wall of the diffuser is provided with a channel for releasing carbonic acid solution, so that a certain back pressure can be generated to spray the supersaturated carbonic acid solution into water to be treated; 2) Carbon dioxide gas is fed into the reaction tank at a certain temperature and a certain pressure; 3) The reaction water is pressurized by a water pump and then is sent into a reaction tank from the tank top in a high-pressure mist form; 4) An on-line water quality detector is arranged in the raw water, and the on-line water quality detector is connected with a PLC controller through a signal receiver to control the opening of a control valve. The method can accurately regulate the water quality, greatly reduce the generation of bubbles and greatly improve the utilization rate of carbon dioxide gas.

Description

Method for adding carbonic acid by adopting small carbonic acid solution adding system

Technical Field

The invention belongs to the technical field of water treatment, and relates to a method for adding carbonic acid by adopting a small carbonic acid solution adding system for adjusting the pH value of water, remineralizing or lime softening and other applications. The method for adding carbonic acid by adopting the small carbonic acid solution adding system is suitable for occasions with small water treatment capacity and no need of rapidly and massively generating carbonic acid solution. Such as fish ponds, shrimp ponds, swimming pools, vegetable greenhouses, flower planting, small sea water desalination, etc.

Background

The pH value of the water body is too high and exceeds pH value of 8.0 or even 9, and the subsequent chemical treatment and product quality are seriously affected by the too high and unstable pH value of the water body. For example, the pH of the wastewater end effluent should be controlled to be 6-9; in the process of coagulation and disinfection of a tap water plant, excessive addition of chemical agents is caused due to excessively high and unstable pH, excessive chemical byproducts are generated, and the effluent can not reach the relevant national standard; in the textile printing and dyeing industry, the pH of printing and dyeing process water is unstable, the color fastness of a product is affected, and the defective rate and the fading of the product are caused; in natural water bodies such as rivers, lakes and the like, the pH value is too high and is changed in a waveform due to factors such as oxygen enrichment, algae burst and the like of the water bodies; in water bodies such as fish ponds, shrimp ponds, swimming pools and the like, the pH value is too high due to the addition of bactericides and disinfectants; the vegetable greenhouse and flower planting requires additional carbon dioxide gas to strengthen photosynthesis, and carbon dioxide content can be increased by using carbonated water for irrigation, so that the growth of crops is facilitated; .. water is not located, and is closely related to life and production of people, and the accurate control of the pH of water body is an important ring in the water treatment process flow.

The pH, also known as the hydrogen ion concentration index, the pH value, is a scale of the activity of hydrogen ions in a solution, i.e., a measure of the degree of acid and base in the solution in a general sense. Neutral aqueous ph=7, and the greater the acidic aqueous pH < 7, the more alkaline. The pH value is one of important physical and chemical parameters of water and sewage, and the pH value is one of important indexes of water treatment field control. Adjusting and controlling the pH may promote chemical reactions and create specific physicochemical changes.

In order to adjust the pH of water, an acidulant such as sulfuric acid or hydrochloric acid is mainly used to neutralize the pH of water; the acidulant belongs to strong acid, and the strong acid has various safety problems such as storage, transportation and corrosion, importantly, the pH value is hard to be accurately regulated by using the strong acid, and more importantly, the strong acid destroys alkaline substances in water in the acid-base neutralization reaction process, and the alkaline substances are indispensable in drinking water.

At present, many petrochemical plants around the country are provided with carbon dioxide purification equipment on a large scale under the guidance of relevant national policies, and produce food-grade carbon dioxide gas, so that the price of the carbon dioxide gas is greatly reduced, and the carbon dioxide gas is also convenient for users to purchase locally. Because the cost and the gas resource are easy to obtain, the operation cost of the carbonic acid adding system is almost equal to the use cost of reducing the chemical agent, and through case implementation, the user only needs to input initial equipment cost, so that the acid-base value of the water is economically feasible by utilizing carbonic acid for neutralization.

Since carbonic acid is a weak acid and has a buffer zone when reacting with an alkaline substance, the pH can be precisely controlled or adjusted to a set value required by a customer by utilizing the neutralization reaction of carbonic acid. In addition, most of carbon dioxide gas is derived from petrochemical waste gas, and pH of water neutralized by carbonic acid solution is the process of carbon dioxide consumption and complete reaction, and carbon dioxide is not released into the atmosphere again, so that greenhouse effect can be reduced, and carbon neutralization is realized.

In the water treatment production process flow of a tap water plant, coagulation and disinfection are essential important links, and how to adjust the pH of raw water, so that the use of chemical agents and byproducts are reduced, and the method has important significance.

In the seawater desalination process, the seawater is subjected to multistage filtration to obtain the permeable water which is acidic and corrosive due to the removal of minerals, lime is required to be added to remineralize the water, and then carbonic acid is required to react with calcium carbonate which is difficult to dissolve in the water to generate water-soluble calcium bicarbonate, so that the water with the minerals added can be drunk by people.

In sewage treatment, because the hardness of the wastewater is high, people need to add lime to carry out lime softening treatment on the hard water, and then add carbonic acid to combine with calcium ions in the wastewater to generate calcium bicarbonate, so that the hardness of the wastewater is reduced; lime softening treatment is to add slaked lime Ca (OH) 2 into water to react with alkaline components in the water to generate indissolvable CaCO3, wherein slaked lime is a strong alkali substance, the pH of the water after slaked lime is added can reach more than 10, high pH water needs acid neutralization, carbonic acid can be used for accurately regulating the pH to a value desired by a customer, meanwhile, carbonic acid reacts with indissolvable CaCO3 generated in the reaction process of slaked lime and water to generate water-soluble calcium bicarbonate, H2CO3+CaCO3-C=Ca (HCO 3) 2, and the problems of pipeline blockage and the like caused by sediment generation are avoided.

There are also known prior art techniques in which carbon dioxide gas is used to neutralize the ph of water. Carbon dioxide gas is dissolved in water to produce carbonic acid. Solubility, defined as the amount of a particular substance that can be dissolved in a particular solvent (yielding a saturated carbonic acid solution). The solubility (solubility) of carbon dioxide in water at normal temperature and pressure is limited. The carbon dioxide gas needs to react with water for a long time to produce carbonic acid, a process called recarbonation. Thus, the dissolution of carbon dioxide in water is a very slow chemical reaction process which reacts with water to form carbon dioxide (in the form of a water-soluble liquid), carbonic acid, bicarbonate ions and hydrogen ions as the carbon dioxide gas molecules enter the water, of the formula:

CO2+H2O->CO2+H2CO3+HCO3(-)+H(+)；

why this is a very slow chemical reaction process, which is slow because it has to be

The double bond between oxygen and carbon (see formula below) must be broken, which takes time.

One way to neutralize the pH of water using carbon dioxide gas is to directly add carbon dioxide gas to neutralize the pH of water, the adding system needs a large reaction tank with a stirrer, carbon dioxide gas generates small bubbles through a diffuser, and the CO2 small bubbles react with alkaline substances in water for a long time and distance to achieve the purpose of lowering the pH. However, small CO2 bubbles can escape from water in the whole reaction process, the effective utilization rate of carbon dioxide gas can only be between 30 and 60 percent, the low utilization rate of carbon dioxide gas means high use cost, and the pH can only be adjusted to 7, so that certain process requirements cannot be met.

Another way of using carbon dioxide gas to neutralize the pH value of water is to mix the water to be treated with the carbon dioxide gas through a venturi nozzle or a venturi static reaction tank and then add the mixed solution into the water to be treated, and the way can be added into a shallow pool and a long-distance pipeline, but the way also faces the problems of escape of CO2 small bubbles, low reaction efficiency and long reaction time.

The above-mentioned two methods of adding carbon dioxide gas are both referred to as gas adding systems because they use venturi principle to add carbon dioxide gas and mix it with treated water to adjust pH. The gas adding systems have the defects of easy escape of CO2 small bubbles, low reaction efficiency, low carbon dioxide gas utilization rate and long reaction time.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for adding carbonic acid by adopting a small carbonic acid solution adding system, wherein the method is used for adjusting the pH value or hardness or turbidity of water and can greatly improve the utilization rate of carbon dioxide gas.

The technical conception of the invention is as follows: gaseous carbon dioxide with certain pressure and temperature and reaction water with certain pressure (low pH effluent or low hardness effluent or low turbidity effluent treated by adding carbonic acid process) are sent into a reaction tank, and gas and water are mixed in a certain proportion in the tank to generate carbonic acid solution under the action of pressure in the tank; then sealing the saturated carbonic acid solution between the reaction tank and the control valve through the control valve to change the saturated carbonic acid solution into a supersaturated carbonic acid solution; finally, the supersaturated carbonic acid solution is reversely injected into the water to be treated through the diffuser, so that the carbonic acid solution and alkaline substances in the water are subjected to neutralization reaction, the purpose of adjusting the pH value of the water (or the purpose of adjusting the hardness or turbidity of the water can be achieved by reacting with CaCO3 in the water), meanwhile, the generation of bubbles can be greatly reduced, and the utilization rate of carbon dioxide gas is greatly improved.

The invention aims at realizing the following technical scheme:

the invention discloses a method for adding carbonic acid by adopting a small carbonic acid solution adding system, which comprises the following steps:

(1) Establishing a small carbonic acid solution adding system; the small carbonic acid solution adding system comprises a reaction tank, a diffuser, a carbon dioxide gas pipeline and a reaction water pipeline; a water mist nozzle and a carbon dioxide gas nozzle are arranged on the top of the inner tank of the reaction tank; a water pump is arranged on the reaction water pipeline; the outlet of the water pump is connected with a water inlet and a water mist nozzle on the top of the reaction tank through a water pipeline; the carbon dioxide gas pipeline is provided with a pressure regulating valve group; the outlet of the pressure regulating valve group is connected with a carbon dioxide gas inlet and a carbon dioxide gas nozzle at the top of the reaction tank; the carbon dioxide gas reacts with the reaction water in the reaction tank to generate carbonic acid solution; the outlet at the bottom of the reaction tank is connected with the inlet of the diffuser; a control valve or a flow limiting orifice plate or an orifice capable of precisely controlling flow and pressure is arranged on a carbonic acid solution pipeline between an outlet at the bottom of the reaction tank and an inlet of the diffuser; the diffuser is arranged in the water to be treated; the diffuser is a hollow cylindrical object with one end open and the other end closed; a channel for releasing carbonic acid solution is arranged on the cylindrical side wall of the diffuser; the passage for releasing the carbonic acid solution is a small hole or a narrow gap or a combination of the small hole and the narrow gap; the channel for releasing the carbonic acid solution can generate certain back pressure and enable the supersaturated carbonic acid solution to be sprayed into water to be treated at certain outlet pressure, so that a pressure difference of more than 2bar is ensured between the outlet pressure of the diffuser and the pressure of the water to be treated;

The diffuser is arranged in raw water or a water pipeline to be treated, which has water flowing, is positioned at the upstream of water flow, and a passage for releasing carbonic acid solution is arranged on one half of the side wall of the diffuser; the channels for releasing the carbonic acid solution are one or more, or one or more rows; the diffuser is inserted into raw water or a water pipeline perpendicular to the water flow direction, one side of the diffuser, which is provided with a channel for releasing carbonic acid solution, is opposite to the upstream of the water flow, so that carbonic acid solution in the diffuser can be sprayed out from the channel for releasing carbonic acid solution reversely opposite to the water flow, and the carbonic acid solution is sprayed out to react with water in a mixing way, and meanwhile, the pressure on the other side is low, so that vortex can be generated to further strengthen the mixing effect;

or the diffuser is arranged in a pool, a pond or a sewage tank which is to be treated and has no water flowing, and a plurality of or a plurality of rows of passages for releasing carbonic acid solution are arranged on the side walls of both sides of the diffuser or on the whole cylindrical side wall (one or a plurality of circles of small holes and/or narrow gaps can be arranged on the whole cylindrical side wall to realize 360-degree feeding).

(2) Carbon dioxide gas is kept at a certain temperature and a certain pressure and is conveyed to a reaction tank through a carbon dioxide gas pipeline;

(3) Carbon dioxide gas with a certain temperature (more than 20 ℃) and a certain pressure (more than 6 bar) enters the tank top of the reaction tank through a gas pipeline, meanwhile, reaction water (low-pH effluent or low-hardness effluent or low-turbidity effluent treated by adding carbonic acid process) is pressurized to a certain pressure through a water pump, and then is sent into the reaction tank from the tank top through a water pipeline in a high-pressure mist form, and the pressure in the tank is kept at a certain pressure; in a reaction tank, mixing carbon dioxide gas with pressurized reaction water to form a gas-liquid mixture with a certain pressure; because the contact area of the water mist and the carbon dioxide gas is large, and the carbon dioxide gas is rapidly dissolved in water and reacts to generate carbonic acid solution in a set pressure environment; the pressure in the tank is raised to the set pressure along with the continuous feeding of carbon dioxide gas or along with the continuous feeding of water mist with a certain pressure into the tank, and when the pressure in the reaction tank reaches a certain pressure (more than 6 bar), the carbonic acid solution in the reaction tank is converted into saturated carbonic acid solution; the saturated carbonic acid solution is conveyed to a control valve or a limiting orifice plate or an orifice hole capable of precisely controlling flow and pressure through a pipeline at the bottom of the reaction tank, the saturated carbonic acid solution is sealed between the reaction tank and the control valve or the limiting orifice plate or the orifice hole, and the saturated carbonic acid solution becomes supersaturated carbonic acid solution due to continuous pressure in the reaction tank and dissolution of carbon dioxide gas; the supersaturated carbonic acid solution is conveyed to the diffuser through a pipeline by a valve core or a flow limiting pore plate or an orifice in an opened control valve; the supersaturated carbonic acid solution is reversely sprayed into water through passages, i.e. small holes and/or narrow gaps, designed on the diffuser for releasing the carbonic acid solution to form a mixed solution of the carbonic acid solution and a small amount of carbon dioxide microbubbles, the carbonic acid solution meets alkaline substances in the water and starts to perform acid-base neutralization reaction, or the carbonic acid solution meets calcium ions or CaCO3 in the water and reacts, and the small amount of carbon dioxide microbubbles are absorbed by water flow, so that the purposes of neutralizing acid-base or reducing the hardness of the water or reducing the turbidity of the water are achieved;

(4) A water quality on-line detector (such as a pH probe or a water hardness on-line detector or a turbidity on-line detector) is arranged at the downstream of water flow in raw water or a water pipeline or at the water outlet of a pool, a pond or a sewage tank, and is connected with a signal receiver which is connected with the input end of a PLC controller; the output end of the PLC is connected with the control valve; the water quality online detector transmits signals to the signal receiver in real time, and the opening of the control valve is controlled after the signals received by the signal receiver are processed by the PLC so as to control the adding amount of the carbonic acid solution, thereby achieving the pH value or hardness or turbidity which a user wants to control.

Further, the inlet of the reaction water pipeline is connected with the effluent water after the water to be treated is added with carbonic acid (namely, the effluent water treated by the carbonic acid adding system and the carbonic acid adding process is used as water for a water pump, namely, reaction water), namely: the raw water or water pipeline downstream water outlet with water flowing to be treated is connected with the inlet of the water pump through a reaction water pipeline; or the water outlet of the pool, pond or sewage tank to be treated without water flow is connected with the water inlet of the water pump through a reaction water pipeline.

Further, the small carbonic acid solution adding system also comprises a liquid carbon dioxide storage tank, an electronic vaporizer or a fin heat exchanger and a gas heater which are connected in sequence; or the large carbonic acid solution adding system also comprises a Dewar tank or a steel cylinder and a gas heater which are connected in sequence; the outlet of the gas heater is connected with the inlet of the carbon dioxide gas pipeline;

In the step (2), high-pressure low-temperature liquid carbon dioxide is stored in a liquid carbon dioxide storage tank, the liquid carbon dioxide is released from the bottom of the liquid carbon dioxide storage tank and is conveyed to an electronic vaporizer or a fin heat exchanger, and the electronic vaporizer or the fin heat exchanger continuously and quantitatively heats and gasifies the liquid carbon dioxide to be converted into carbon dioxide gas; alternatively, the carbon dioxide gas is stored in a dewar or steel cylinder, and the carbon dioxide gas is released from the dewar or steel cylinder; the carbon dioxide gas is conveyed to a gas heater through a pipeline to be heated to a certain temperature, and then is regulated to a certain pressure through a pressure regulating valve group; the carbon dioxide gas is kept at a certain temperature and a certain pressure and is conveyed to the reaction tank through a carbon dioxide gas pipeline.

In the step (2), the carbon dioxide gas is conveyed to a gas heater through a carbon dioxide gas pipeline to be heated to a temperature above 20 ℃, and then the pressure is regulated to be above 6bar through a pressure regulating valve group; the carbon dioxide gas is maintained at a temperature above 20 ℃ and a pressure above 6 bar.

Further, in the step (3), carbon dioxide gas with the temperature of more than 20 ℃ and the pressure of more than 6bar enters the tank top of the reaction tank through a gas pipeline, meanwhile, reaction water (low-pH effluent or low-hardness effluent or low-turbidity effluent after being treated by a carbonic acid adding process) is pressurized to more than 3bar through a water pump, and then is sent into the reaction tank from the tank top through a water pipeline in a high-pressure mist mode, and the pressure in the tank is kept to be more than 3 bar.

Further, when the diffuser is arranged in raw water or a water pipeline to be treated, which flows with water, the diffuser is a hollow long cylindrical object with one closed end and one polygonal half of the cross section and the other circular arc, and a plurality of passages for releasing carbonic acid solution are formed in one side wall of one polygonal half of the diffuser; the passage for releasing the carbonic acid solution is one or more rows of small holes, one or more rows of narrow slits, or a combination of one or more rows of small holes and one or more rows of narrow slits (i.e. a combination of small holes and narrow slits); or may be one or more small holes, one or more narrow slits, or a combination of one or more small holes and one or more narrow slits (i.e., a combination of both small holes and narrow slits); the diffuser is inserted into the raw water perpendicular to the water flow direction, and one side of the diffuser with small holes and/or narrow slits faces to the upstream of the water flow, so that the carbonic acid solution in the diffuser can be sprayed from the small holes and/or narrow slits reversely to the water flow.

When the diffuser is arranged in a pool, a pond or a sewage tank which is to be treated and has no water flow, the diffuser for realizing 360-degree casting can be designed into a hollow cylinder, and can be also designed into a square cylinder with a polygonal cross section (such as square, hexagon and the like) on the premise of ensuring back pressure.

Still further, the apertures and/or slots in each row are located on the same vertical line and are uniformly aligned.

Further, a plurality of channels for releasing carbonic acid solution on the same horizontal plane are uniformly arranged with a center included angle smaller than 180 degrees; two adjacent channels for releasing carbonic acid solution on the same horizontal plane are arranged at an acute central included angle so as to ensure that the carbonic acid solution is ejected out to be mixed with water to be treated in the water flow direction at a certain outlet pressure (more than 3 bar), and the vortex strengthening mixing effect can be generated.

Further, the small holes are designed for small diameter pipes below DN25, i.e. when the long distance pipe is a small diameter pipe below DN25, the passage for releasing carbonic acid solution is one or more rows of small holes, or a combination of one or more rows of small holes and one or more rows of narrow slits; either one or more small holes or a combination of one or more small holes and one or more narrow slits; the narrow slit is more suitable for large pipe diameters larger than DN25, i.e. when the long distance pipe is a large pipe diameter larger than DN25, the passage for releasing carbonic acid solution is one or more rows of narrow slits, or a combination of one or more rows of small holes and one or more rows of narrow slits; or one or more narrow slits, or a combination of one or more apertures and one or more narrow slits.

Further, the volume ratio of the carbon dioxide gas with the temperature of more than 20 ℃ and the pressure of more than 6bar to the reaction water (low pH effluent or low hardness effluent or low turbidity effluent after being treated by adding carbonic acid process) is not lower than 1: 40.

Further, the channels for releasing carbonic acid solution can generate a back pressure of more than 3bar and enable supersaturated carbonic acid solution to be sprayed into water to be treated at an outlet pressure of more than 3 bar; the diffuser back pressure was greater than 3bar and the pressure of the entire system was maintained at greater than 3bar. The saturated carbonic acid solution can be further converted into supersaturated carbonic acid solution by keeping the pressure of the system to be more than 3bar, otherwise, the utilization rate of the carbon dioxide above 97% is affected. The concentration of carbonic acid solution is more than 99% before the outlet of the diffuser, and when the carbonic acid solution passes through small holes and narrow gaps, a small amount of carbonic acid overflows from the solution in the form of bubbles due to pressure drop, so that the utilization rate of the whole carbonic acid is more than 97%.

The working principle of the method for adding carbonic acid by adopting the small carbonic acid solution adding system is as follows: the high-pressure low-temperature liquid carbon dioxide is stored in a liquid carbon dioxide storage tank, the liquid carbon dioxide comes out from the bottom of the liquid carbon dioxide storage tank and is conveyed to an electronic vaporizer or a fin heat exchanger, and the liquid carbon dioxide is continuously and quantitatively converted into carbon dioxide gas; alternatively, carbon dioxide gas is stored in a dewar or cylinder from which the carbon dioxide gas is released; the carbon dioxide gas passes through a gas heater, the temperature of the carbon dioxide gas is kept above 20 ℃, and the pressure of the carbon dioxide gas is regulated to be above 6bar through a pressure regulating valve group 10; carbon dioxide gas with the temperature of more than 20 ℃ and the pressure of more than 6bar is sent into the reaction tank from the tank top through a gas pipeline, and air in the tank is discharged; meanwhile, the reaction water (low pH effluent or low hardness effluent or low turbidity effluent treated by adding carbonic acid process) is pressurized to more than 3bar by a water pump, and then is sent into a reaction tank from the tank top in a high-pressure mist form through a water pipeline, and the pressure in the tank is kept to be more than 3 bar; in the reaction tank, carbon dioxide gas is mixed with pressurized reaction water to form a gas-liquid mixture with a certain pressure; because the contact area between the water mist and the carbon dioxide gas is large, and the carbon dioxide gas is rapidly dissolved in water and reacts to generate carbonic acid solution in a set pressure environment; the method comprises the steps of continuously feeding carbon dioxide gas or continuously feeding water mist with a certain pressure into a tank, lifting the pressure in the tank to a set pressure, and converting carbonic acid solution in the tank into saturated carbonic acid solution when the pressure in a reaction tank reaches more than 6 bar; the saturated carbonic acid solution is conveyed to a control valve or a limiting orifice plate or an orifice hole capable of precisely controlling flow and pressure through a pipeline at the bottom of the reaction tank, the saturated carbonic acid solution is sealed between the reaction tank and the control valve or the limiting orifice plate or the orifice hole, and the saturated carbonic acid solution is supersaturated carbonic acid solution due to continuous pressure in the reaction tank and dissolution of carbon dioxide gas; the supersaturated carbonic acid solution is conveyed to the diffuser through a pipeline by a valve core or a flow limiting orifice plate or a flow limiting orifice in an opened control valve; the supersaturated carbonic acid solution is reversely sprayed into water through passages, i.e. small holes and/or narrow gaps, designed on the diffuser for releasing the carbonic acid solution to form a mixed solution of the carbonic acid solution and a small amount of carbon dioxide microbubbles, the carbonic acid solution meets alkaline substances in the water and starts to perform acid-base neutralization reaction, or the carbonic acid solution meets calcium ions or CaCO3 in the water to react, and the small amount of carbon dioxide microbubbles are absorbed by water flow, so that the purposes of neutralizing acid and alkali or reducing the hardness of the water or reducing the turbidity of the water are achieved. The water quality on-line detector (pH probe or water hardness on-line detector) is arranged at the downstream of the water flow in the raw water or water pipeline or at the water outlet of the pool, pond or sewage tank, and transmits signals to the signal receiver on the control valve in real time, and the opening of the control valve is controlled after the signals received by the signal receiver are processed by the PLC so as to control the adding amount of carbonic acid solution, thereby achieving the pH, hardness or turbidity which the user hopes to control.

A liquid level meter with signal output is arranged outside the tank body of the reaction tank, and a liquid level signal of carbonic acid solution in the tank is used for controlling a water pump and a switch for injecting carbon dioxide gas through a PLC processor. When the liquid level is lowered, the PLC processor controls the water pump and the carbon dioxide gas injection switch to be turned on, so as to generate carbonic acid solution, and the carbonic acid solution is added into water to supplement the amount of the carbonic acid solution which is consumed by neutralization.

The carbon dioxide gas is gasified and heated to a temperature above 20 ℃ and a pressure above 6bar, the water is pressurized to a pressure above 3bar by a water pump, and the two are mixed in a reaction tank and under the pressure condition, so as to generate carbonic acid solution. The saturated carbonic acid solution can be further converted into the supersaturated carbonic acid solution by keeping the pressure of the system to be more than 3bar, otherwise, the utilization rate of the carbon dioxide of more than 97% can be influenced. The concentration of carbonic acid solution is more than 99% before the outlet of the diffuser, and when the carbonic acid solution passes through small holes and narrow gaps, a small amount of carbon dioxide overflows from the solution in the form of bubbles due to pressure drop, so that the utilization rate of the whole carbon dioxide is more than 97%.

The solubility of carbon dioxide gas is related to temperature, pressure: under the same pressure condition, the lower the temperature is, the higher the solubility is; under the same temperature condition, the higher the pressure is, the higher the solubility is; therefore, the generation of carbonic acid can be enhanced or accelerated by lowering the water temperature and increasing the pressure in the tank. According to the conditions of each use scene, such as water temperature, water pressure, water quality parameters of raw water (water to be treated), stable pH value or hardness or turbidity expected by a user, the position of a carbonic acid adding point and the like, the parameters of the water pump and the dosage of carbon dioxide gas can be selected.

By using an electronic vaporizer or a fin heat exchanger, the cryogenic liquid carbon dioxide can be vaporized to gaseous carbon dioxide using electrical heating or air heat exchange principles. The carbon dioxide in the liquid carbon dioxide storage tank is liquid carbon dioxide with the temperature below 0 ℃ and the pressure of about 17-23bar, the temperature of the gaseous carbon dioxide passing through the electronic vaporizer or the fin heat exchanger is 0-10 ℃, the pressure can be adjusted to 5-10bar, the gaseous carbon dioxide is filled into the reaction tank through the gas heater and the gas pipeline to meet low pH or low hardness or low turbidity water mist, and because the carbon dioxide enters the reaction tank in a depressurization process, the carbon dioxide gas can generate dry ice in the depressurization process to affect the dissolution and the equipment efficiency of the carbon dioxide gas, a gas heater is additionally arranged behind the electronic vaporizer or the fin heat exchanger, and the temperature of the carbon dioxide gas is increased to above 20 ℃ through the gas heater to prevent the generation of dry ice during filling of the carbon dioxide gas.

The method for reducing water temperature and increasing pressure in the tank can strengthen or accelerate the generation of carbonic acid, for example, a water cooling system … added in the system can be provided with a cooling liquid coil pipe in the reaction tank, or a cooling water pipe added in the middle lower part of the reaction tank.

The liquid carbon dioxide is gasified and warmed to prevent dry ice from being generated. The dry ice can be prevented from being generated even without the heating devices in a high-temperature environment. The method of utilizing venturi gas-water is not limited to the venturi form herein.

Control valves capable of controlling flow and pressure, other forms of similar control methods such as restriction orifice plates, orifices, etc., which are readily conceivable, take advantage of this principle.

The water is mixed with carbon dioxide gas in the form of mist to increase the contact area and speed up the mixing to produce a carbonic acid solution, and the principle is utilized to reduce the size of the low pH or low hardness or low turbidity water mist and mist mixture, such as nano-scale. Therefore, the water mist nozzle at the top of the reaction tank can adopt an industrial sonic nanoscale atomizer.

The invention has the beneficial effects that:

the invention provides a method for adding carbonic acid by adopting a small carbonic acid solution adding system, which comprises the steps of sending carbon dioxide gas and reaction water into a reaction tank to prepare supersaturated carbonic acid solution in advance, and adding the supersaturated carbonic acid solution into water through a diffuser, so as to adjust the pH value or hardness or turbidity of the water.

Compared with the prior art, the method for adding carbonic acid by adopting the small carbonic acid solution adding system has the following advantages:

1) In the invention, gaseous carbon dioxide with certain pressure and temperature and reaction water with certain pressure are sent into a reaction tank to be premixed into a gas-liquid mixture at the top of the tank according to a certain proportion, and carbonic acid solution is generated by utilizing the pressure in the tank; then sealing the saturated carbonic acid solution between the reaction tank and the control valve through the control valve to change the saturated carbonic acid solution into supersaturated carbonic acid solution; finally, reversely injecting the supersaturated carbonic acid solution into the water to be treated through the diffuser, so that the carbonic acid solution and alkaline substances in the water are subjected to neutralization reaction, the purpose of adjusting the pH value or the hardness or the turbidity of the water can be achieved, the pH value or the hardness or the turbidity of the water can be accurately adjusted, the generation of bubbles can be greatly reduced, and the utilization rate of carbon dioxide gas can be greatly improved.

2) The supersaturated carbonic acid solution is put into the water through a diffuser, and because the pressure of the water is in a low pressure state, in order to avoid a great deal of escape of carbon dioxide bubbles in the mixed solution in the pressure drop, the invention designs the diffuser, and the diffuser has the functions of stabilizing the pressure of the system, maintaining the back pressure of the system and injecting the carbonic acid solution into the treated water. The supersaturated carbonic acid solution is sprayed out through the small holes of the diffuser, and then acid-base neutralization reaction is carried out on the supersaturated carbonic acid solution and alkaline substances in water. Because of the pressure drop, a small amount of carbon dioxide bubbles escape from the carbonic acid solution, so that the small amount of carbon dioxide bubbles and the high-concentration carbonic acid solution are ejected together to generate strong vortex with water, the reaction speed is increased, and the reaction time is shortened. Through application of test cases, the gas-water mixture or the mixed solution is converted into supersaturated carbonic acid solution (the concentration of carbonic acid is more than 99%, the effective utilization rate of carbon dioxide gas is more than 97%), the reaction of the carbonic acid solution and water is liquid-liquid reaction, the neutralization reaction time is completed within 20-30 seconds, the minimum pH can reach 5, and the pH fluctuation can be accurately and stably controlled. Compared with the carbon dioxide adding mode, the invention does not need an additional reaction tank, has high carbon dioxide utilization rate and greatly reduces the use cost of users.

3) In the prior art, a mode of adding carbon dioxide gas is used, a venturi nozzle or a venturi static reaction tank is a component for projecting the gas into water, and the gas and the water are mixed at a constriction section or a throat pipe of the venturi nozzle and then are ejected out through a dilation section. The injection speed of the solution is increased, the pressure is rapidly reduced, a large amount of carbon dioxide gas is separated out from the solution to form large bubbles, and only a small part of carbon dioxide gas reacts with water to generate carbonic acid. Because the pressure in the water is different at different heights, carbon dioxide bubbles escape from the water in open environments such as shallow ponds, water pools and the like; carbon dioxide bubbles in the pipeline can collapse, cause vibration and cavitation, and affect the accuracy of the pH.

The main function of the diffuser in the invention is to stabilize the pressure of the whole system to be more than 3bar by using small holes and/or narrow slits, always seal the carbon dioxide gas in the supersaturated carbonic acid solution, and generate stable carbonic acid solution and a small amount of carbon dioxide bubbles when the pressure is released. A passage for releasing carbonic acid solution is formed in one half of the side wall of the diffuser, and the passage for releasing carbonic acid solution is one or more rows of small holes, one or more rows of narrow gaps, or two combinations of small holes and/or narrow gaps; a plurality of channels for releasing carbonic acid solution on the same horizontal plane are uniformly arranged at a center included angle smaller than 180 degrees; two adjacent channels for releasing carbonic acid solution on the same horizontal plane are arranged at an acute central included angle so as to ensure that the outlet pressure of the carbonic acid solution is more than 3bar to be ejected and mixed with water to be treated. The inlet pressure and the outlet pressure of the pressure mixture (ideal) are identical through small holes and/or narrow slits and are injected into the water at a very fast rate. Because the pressure drops, partial carbon dioxide gas can escape from the solution in the form of micro bubbles due to the pressure difference, so that the mixed solution of carbonic acid solution and micro bubbles is sprayed together to be mixed with water, and meanwhile, because the small holes and/or narrow gaps on each row are positioned on the same vertical line and are uniformly arranged, the pressure difference between the side with holes of the diffuser and the side without holes is formed, the pressure mixed solution forms vortex in the water, and the acid-base neutralization reaction is further accelerated.

In the present invention, a diffuser for spraying a carbonic acid solution, a narrow slit and a small hole are used in combination or alone, and the small hole or the combination of the narrow slit and the small hole is designed for a small-pipe diameter pipe having a DN25 or less; the narrow gap or the combination of the narrow gap and the small hole is more suitable for large-diameter pipelines larger than DN 25; the contact surface between the solution ejected through the narrow gap and water is larger than that of the solution ejected through the small hole; depending on the use scenario, a combined design of small holes and/or narrow slits is also applied. The liquid flowing through the small holes is a process of shrinkage and re-diffusion, the state of the liquid is turbulent, great pressure loss is generated, and more carbon dioxide gas is separated out due to the excessive small holes. Compared to small holes, the state of the liquid passing through the narrow gap and the pressure being lower than 10bar is a laminar flow, where the carbon dioxide is precipitated much less than in small holes. However, in some cases, small holes and narrow slits are combined, and a small amount of carbon dioxide gas is required to be lost, so that a certain turbulence is formed, and the mixing effect with raw water is enhanced. Compared with the small holes, the narrow gap can solve the problem that the small holes deform due to cavitation and influence the solution ejection flow and pressure in the use of the system.

Compared with a Venturi nozzle or a Venturi static reaction tank in the prior art, the carbonic acid solution diffuser solves the problems of low utilization rate (dissolution rate) of carbon dioxide gas, noise, vibration, cavitation and the like; meanwhile, the application scene range of adding the carbonic acid solution is wider, and the carbonic acid solution can be applied to natural lakes, shallow ditches, shallow ponds, pipelines, liquid tanks and the like.

4) The invention solves the problems that the gas and the water with different pressures are mixed and the carbon dioxide gas is easy to separate out from the liquid; the pressure and time required for converting the gas-water mixture into supersaturated carbonic acid solution are solved by the design of the reaction tank, and the carbonic acid solution is kept stable in the closed pressure environment.

Drawings

FIG. 1 is a schematic view of the overall structure of a small-sized carbonic acid solution feeding system of the present invention (the diffuser 6 is disposed in a water pipe having water flowing therein to be treated);

FIG. 2 is a schematic view of the overall structure of a small carbonic acid solution feeding system of the present invention (the diffuser 6 is disposed in a pool of water to be treated without water flow);

FIG. 3 is a schematic cross-sectional top view of a diffuser 6 of the present invention;

fig. 4 is a schematic front view of the diffuser 6 according to the present invention;

Fig. 5 is a schematic side view of the diffuser 6 according to the present invention.

In the figure: 1. a liquid carbon dioxide storage tank 2, an electronic carburetor 3, a gas heater 4, a water pump 5, a reaction tank 6, a diffuser 7, a pH probe 8, a narrow slit 9, a small hole 10, a pressure regulating valve group 11, a reaction water pipeline 12, a carbon dioxide gas pipeline 13, a carbon dioxide gas injection switch 14, a control valve 15, a carbonic acid solution pipeline A, a center included angle B and a center included angle

Detailed Description

The invention is further described below with reference to the drawings and examples.

Example 1

The method for adding carbonic acid by adopting a small carbonic acid solution adding system for adjusting the pH value of water comprises the following steps:

(1) Establishing a small carbonic acid solution adding system; as shown in fig. 1, the small carbonic acid solution adding system comprises a liquid carbon dioxide storage tank 1, an electronic carburetor 2, a gas heater 3, a reaction tank 5, a diffuser 6, a water pump 4, a reaction water pipeline 11 and a carbon dioxide gas pipeline 12 which are connected in sequence; a water mist nozzle (connected with a reaction water pipeline 11) and a carbon dioxide nozzle (connected with a carbon dioxide pipeline 12) are arranged on the top of the inner tank of the reaction tank 5; the water pump 4 is arranged on the reaction water pipeline 11; the outlet of the water pump 4 is connected with a water inlet and a water mist nozzle on the tank top of the reaction tank 5 through a reaction water pipeline 11; the outlet of the gas heater 3 is connected with a carbon dioxide inlet and a carbon dioxide nozzle at the top of the reaction tank 5 through a carbon dioxide pipeline 12; the carbon dioxide gas pipeline 12 is provided with a pressure regulating valve group 10; the outlet of the pressure regulating valve group 10 is connected with a carbon dioxide inlet and a carbon dioxide nozzle at the top of the reaction tank 5 through a carbon dioxide pipeline 12; the carbon dioxide gas reacts with the reaction water in the reaction tank 5 to generate carbonic acid solution; a small section of each of the reaction water pipeline 11 and the carbon dioxide gas pipeline 12 extends into the reaction tank 5; the outlet at the bottom of the reaction tank 5 is connected with the inlet of the diffuser 6; a control valve 14 capable of precisely controlling flow and pressure is arranged on a carbonic acid solution pipeline between the outlet of the bottom of the reaction tank 5 and the inlet of the diffuser 6. The diffuser 6 is arranged in a water pipeline to be treated, which is provided with water flow, is positioned at the upstream of water flow, and is inserted into the water pipeline perpendicular to the water flow direction; a plurality of passages for releasing carbonic acid solution are arranged on one half of the side wall of the diffuser 6, and can generate back pressure of more than 3bar and enable supersaturated carbonic acid solution to be sprayed into water to be treated (reversely sprayed into water upstream of water flow) at an outlet pressure of more than 3bar, so that a pressure difference of more than 2bar is ensured between the outlet pressure of the diffuser and the pressure of the water to be treated; the downstream water outlet of the water pipeline with water flowing to be treated is connected with the inlet of the water pump 4 through a reaction water pipeline 11 (the low pH water treated by the carbonic acid adding system and the carbonic acid adding process of the invention is used as water for the water pump 4, namely reaction water);

(2) Storing high-pressure low-temperature liquid carbon dioxide in a liquid carbon dioxide storage tank 1; the liquid carbon dioxide is released from the bottom of the liquid carbon dioxide storage tank 1 and is conveyed to the electronic vaporizer 2, and the electronic vaporizer 2 continuously and quantitatively heats and gasifies the liquid carbon dioxide to be converted into gaseous carbon dioxide (carbon dioxide gas); the carbon dioxide gas is conveyed to a gas heater 3 through a pipeline to be heated to a temperature above 20 ℃, and then the pressure is regulated to be above 6bar through a pressure regulating valve group 10; the carbon dioxide gas is kept at a temperature of 20 ℃ or higher and a pressure of 6bar or higher and is conveyed to the reaction tank 5 through a pipeline;

(3) Carbon dioxide gas with the temperature of more than 20 ℃ and the pressure of more than 6bar enters the top of the reaction tank 5 (sprayed out from a carbon dioxide gas nozzle) through a gas pipeline 12, meanwhile, low-pH water (low-pH water outlet after being treated by adding carbonic acid) is pressurized to more than 3bar through a water pump 4, and then is sent into the reaction tank 5 from the top of the tank (entering from a water inlet on the top of the tank and sprayed out from a water mist nozzle on the top of the tank) through a water pipeline 11 in a high-pressure mist form, and the pressure in the tank is kept to be more than 3 bar; the volume ratio of carbon dioxide gas having a temperature of 20 ℃ or higher and a pressure of 6bar or higher to low pH water is 1:40, a step of performing a; in the reaction tank 5, carbon dioxide gas is mixed with pressurized reaction water to form a gas-liquid mixture having a certain pressure; because the contact area between the water mist and the carbon dioxide gas is large, and the carbon dioxide gas is rapidly dissolved in water and reacts to generate carbonic acid solution in a set pressure environment; along with the continuous feeding of the carbon dioxide gas, when the pressure in the reaction tank 5 reaches more than 6bar, the carbonic acid solution in the tank is converted into saturated carbonic acid solution; the saturated carbonic acid solution is conveyed to a control valve 14 capable of precisely controlling flow and pressure through a pipeline at the bottom of the reaction tank 5, the control valve 14 seals the saturated carbonic acid solution between the reaction tank 5 and the control valve 14, and the saturated carbonic acid solution becomes supersaturated carbonic acid solution due to the continuous pressure in the reaction tank 5; the control valve 14 is opened, supersaturated carbonic acid solution is conveyed to the diffuser 6 through a valve core in the control valve 14, a mixed solution of high-concentration carbonic acid solution and a small amount of carbon dioxide microbubbles is reversely sprayed into water to be treated (raw water) through small holes 9 and/or narrow slits 8 which are designed on the diffuser 6 and are used for releasing the carbonic acid solution, the carbonic acid solution meets alkaline substances in the water and starts to perform acid-base neutralization reaction, and a small amount of carbon dioxide microbubbles are absorbed by water flow so as to achieve the aim of neutralizing acid-base;

(4) A pH probe 7 is arranged at the downstream of water flow in a water pipeline, the pH probe 7 is connected with a signal receiver, and the signal receiver is connected with the input end of a PLC controller; the output end of the PLC is connected with the control valve 14; the pH probe 7 transmits signals to a signal receiver in real time, and the signal received by the signal receiver is processed by the PLC to control the opening of the control valve 14 so as to control the dosage of the carbonic acid solution, thereby achieving the pH value which the user wants to control.

As shown in fig. 3-5, the diffuser 6 is a hollow long cylindrical object with one closed end and a polygonal half and an arc-shaped half, and a plurality of passages for releasing carbonic acid solution are formed on one half side wall of one side of the polygonal shape of the diffuser 6; the passage for releasing the carbonic acid solution is a combination of small holes and narrow gaps, a row of small holes 9 are arranged in the middle, and a row of narrow gaps 8 are respectively arranged at two sides; the two adjacent channels (small holes 9 and/or narrow slits 8) for releasing carbonic acid solution on the same horizontal plane are arranged at an acute central included angle (i.e. the central included angle formed by the connection line of the two adjacent channels for releasing carbonic acid solution and the central point is an acute angle, as in A, B in fig. 3, the two central included angles are acute angles), so as to ensure that the carbonic acid solution is ejected to be mixed with water to be treated in the water flow direction at an outlet pressure of more than 3bar, and the vortex strengthening mixing effect can be generated.

As shown in fig. 5, the diffuser 6 is arranged in the water pipe to be treated, where there is a flow of water, upstream of the flow of water; the diffuser 6 is inserted into the water pipeline perpendicular to the water flow direction, one side of the diffuser 6 provided with the small holes 9 and the narrow gaps 8 is opposite to the water flow upstream, so that the carbonic acid solution in the diffuser 6 can be sprayed out from the small holes 9 and the narrow gaps 8 reversely opposite to the water flow, and the carbonic acid solution is sprayed out to react with the water in a mixing way, and meanwhile, the pressure on the other side is low, so that vortex can be generated to further strengthen the mixing effect.

The small holes 9 and the narrow slits 8 in the diffuser 6 can generate a back pressure of more than 3bar and enable the supersaturated carbonic acid solution to be sprayed into the water to be treated in the water pipeline at an outlet pressure of more than 3bar (reversely sprayed into the water upstream of the water flow), so that a pressure difference of more than 2bar is ensured between the outlet pressure of the diffuser 6 and the pressure of the water to be treated.

The working principle of the method for adding carbonic acid by adopting the small carbonic acid solution adding system in the embodiment is as follows: the high-pressure low-temperature liquid carbon dioxide is stored in a liquid carbon dioxide storage tank 1; the liquid carbon dioxide comes out of the bottom of the liquid carbon dioxide storage tank 1 and is conveyed to the electronic carburetor 2, and the liquid carbon dioxide is continuously and quantitatively converted into carbon dioxide gas; the carbon dioxide gas passes through a gas heater 3, maintains the temperature above 20 ℃, and then adjusts the pressure to above 6bar through a pressure regulating valve group 10; carbon dioxide gas having a temperature of 20 ℃ or higher and a pressure of 6bar or higher is fed into the reaction tank 5 from the tank top (ejected from a carbon dioxide gas nozzle) through the gas pipe 12, and the air in the tank is discharged; meanwhile, low-pH water (low-pH water after being treated by adding carbonic acid) is pressurized to more than 3bar through a water pump 4, is sent into a reaction tank 5 from the top of the tank (sprayed out from a water mist nozzle) in a high-pressure mist form through a water pipeline 11, and keeps the pressure in the tank to be more than 3 bar; in the reaction tank 5, carbon dioxide gas is mixed with pressurized reaction water mist to form a gas-liquid mixture with a certain pressure; because the contact area between the water mist and the carbon dioxide gas is large, and the carbon dioxide gas is rapidly dissolved in water and reacts to generate carbonic acid solution in a set pressure environment; along with the continuous feeding of carbon dioxide gas, when the pressure in the reaction tank reaches more than 6bar, the carbonic acid solution in the tank is converted into saturated carbonic acid solution; the saturated carbonic acid solution is conveyed to a control valve 14 capable of precisely controlling flow and pressure through a pipeline at the bottom of the reaction tank 5, the control valve 14 seals the saturated carbonic acid solution between the reaction tank 5 and the control valve 14, and the saturated carbonic acid solution becomes supersaturated carbonic acid solution due to the continuous pressure in the reaction tank 5; the control valve 14 is opened, the supersaturated carbonic acid solution is conveyed to the diffuser 6 through a valve core in the control valve 14, a mixed solution of the high-concentration carbonic acid solution and a small amount of carbon dioxide microbubbles is reversely sprayed into water through a channel designed on the diffuser 6 for releasing the carbonic acid solution, namely the small holes 9 and/or the narrow gaps 8, the carbonic acid solution meets alkaline substances in the water and starts to perform acid-base neutralization reaction, and a small amount of carbon dioxide microbubbles are absorbed by water flow so as to achieve the aim of neutralizing the acid-base. The pH probe 7 is arranged at the downstream of the water flow in the water pipeline and transmits a pH signal to a signal receiver on the control valve 14 in real time, and the signal received by the signal receiver is processed by the PLC and then controls the opening of the control valve 14 so as to control the dosage of the carbonic acid solution, thereby achieving the pH value which a user wants to control.

A liquid level meter (not labeled in the figure) with signal output is arranged outside the tank body of the reaction tank 5, and the liquid level signal of the carbonic acid solution in the tank is used for controlling the water pump 4 and the switch 13 for injecting carbon dioxide gas through the PLC processor. When the liquid level drops, the PLC processor controls the water pump 4 and the carbon dioxide gas injection switch 13 to be turned on, so as to generate carbonic acid solution, and the carbonic acid solution is added into water to supplement the amount of the carbonic acid solution which is consumed by neutralization.

The pH values of the raw water and the water to be treated are unstable and fluctuate between 8 and 12, after the carbonic acid is added in the carbonic acid adding process, the pH can be reduced and stabilized at the low pH required by customers, and the low pH effluent which is treated by the carbonic acid adding process and is stabilized at the low pH required by customers is used as water for a water pump. Such as: the pH of raw water in a tap water plant fluctuates between 8 and 9, the pH required by customers is 7, and low pH effluent water which is treated by the carbonic acid processing technique of the present invention and is stabilized at pH 7 is used as water for the water pump 4 (reaction water). The pH of the printing and dyeing wastewater fluctuates between 9 and 12, the pH required by customers is 8.5, the pH of the effluent water treated by the carbonic acid processing technology can be stabilized at 8.5, and the low pH effluent water treated by the carbonic acid processing technology and stabilized at 8.5 is used as water for a water pump 4 (reaction water). The pH value of the water to be treated is unstable, the pH value is stable after carbonic acid is added, and the water with the stable pH value can reduce the adding amount of carbon dioxide in the next batch of water to be treated if the carbon dioxide is contained in the water after carbonic acid is added. The method is a process of recycling carbon dioxide, ensures the pH stability of the effluent, and uses as little carbon dioxide gas as possible.

Mixing carbon dioxide gas with a certain pressure and heating with pressurized reaction water to form a gas-water mixture with pressure, and converting the gas-water mixture into saturated carbonic acid solution in a reaction tank 5; the saturated carbonic acid solution is sealed between the reaction tank 5 and the control valve 14 to form supersaturated carbonic acid solution; the supersaturated carbonic acid solution is put into water through the diffuser 6 (shown in fig. 3 to 5) (the supersaturated carbonic acid solution is more capable of reducing the generation of bubbles than the saturated carbonic acid solution); since the pressure of the water is low, the present invention contemplates this diffuser 6 (shown in fig. 3-5) in order to avoid a large escape of carbon dioxide bubbles in the mixed liquor in the pressure drop, the function of this diffuser 6 being to stabilize the pressure of the system, maintain the back pressure of the system and inject the carbonic acid solution into the treated water. The supersaturated carbonic acid solution is sprayed out through the small holes 9 and the narrow slits 8 on the diffuser 6, and acid-base neutralization reaction is carried out on the supersaturated carbonic acid solution and alkaline substances in water. Because of the pressure drop, a small amount of carbon dioxide bubbles escape from the carbonic acid solution, so that the small amount of carbon dioxide bubbles and the carbonic acid solution are ejected together and strongly vortex with water, the reaction speed is increased, and the reaction time is shortened. Through application of test cases, the gas-water mixture or the mixed solution is converted into supersaturated carbonic acid solution (the concentration of carbonic acid reaches more than 99 percent, the effective utilization rate of carbon dioxide gas reaches more than 97 percent), the acid-base neutralization reaction of the carbonic acid solution and alkaline substances in water is a liquid-liquid reaction, the neutralization reaction time is completed within 20-30 seconds, the minimum pH value can reach 5, and the pH fluctuation can be accurately and stably controlled. Compared with the carbon dioxide adding mode, the invention does not need an additional reaction tank, has high carbon dioxide utilization rate and greatly reduces the use cost of users.

The diffuser 6 is a hollow polygonal long cylindrical object with one closed end, and is inserted perpendicular to the water flow direction, one surface of the diffuser 6 with small holes 9 and/or narrow slits 8 faces the upstream of the water flow (see fig. 5), and an opening (one end which is not closed) at the top end of the diffuser 6 can allow supersaturated carbonic acid solution to enter, and the supersaturated carbonic acid solution is mixed with the water after being sprayed from the small holes 9 and/or the narrow slits 8 reversely against the water flow. The process of the solution entering the water is a depressurization process, in which the carbonic acid pressure solution and a small amount of carbon dioxide bubbles form vortex with the upstream of the water flow and the downstream of the water flow at the moment of injection through the small holes 9 and/or the narrow slits 8, the small bubbles are absorbed by the water flow, and the carbonic acid solution reacts with the water, and the whole process is a process of intensified mixing and rapid neutralization reaction.

Role of the diffuser 6: in addition to injecting the carbonic acid solution into the water, while maintaining the pressure of the entire system, escape of carbon dioxide gas from the carbonic acid solution is prevented. The back pressure of the system is kept to be more than 3bar by the small holes 9 and the narrow gaps 8 on the diffuser 6, the supersaturated carbonic acid solution is reversely sprayed into water to be treated through the small holes 9 and the narrow gaps 8 on the diffuser 6, and the carbonic acid solution can rapidly react with alkaline substances in the water while carbon dioxide bubbles are absorbed by water vortex, so that the purpose of neutralizing the pH value is achieved. This system back pressure will maintain the overall conversion process and pipeline pressure and will prevent carbon dioxide bubbles from escaping from the carbonic acid solution due to the pressure drop and prevent the carbonic acid solution from returning to the gas-water mixture state.

In summary, the invention provides a complete method for adding carbonic acid by adopting a small carbonic acid solution adding system, which is to react gaseous carbon dioxide with low-pH water in a tank to generate supersaturated carbonic acid solution, and then add the supersaturated carbonic acid solution into the water through a diffuser so as to adjust the pH of the water.

In the prior art, a mode of adding carbon dioxide gas is used, a venturi nozzle is a component for projecting gas into water, and the gas and the water are mixed at a constriction section or a throat pipe of the venturi nozzle and then are ejected through an expansion section. The injection speed of the solution is increased, the pressure is rapidly reduced, a large amount of carbon dioxide gas is separated out from the solution to form atmospheric bubbles, and only a small part of the carbon dioxide gas reacts with water to generate carbonic acid. Because the pressure in the water is different at different heights, carbon dioxide bubbles escape from the water in open environments such as shallow ponds, water pools and the like; carbon dioxide bubbles in the pipeline can collapse, cause vibration and cavitation, and affect the accuracy of pH control.

The main function of the diffuser 6 in the present invention is to stabilize the pressure of the whole system above 3bar by means of the small holes 9 and the narrow slits 8 shown in fig. 3-5, to always seal the carbon dioxide gas in the supersaturated carbonic acid solution, and to generate a stable carbonic acid solution and a small amount of carbon dioxide bubbles when the pressure is released. As shown in fig. 3-5, a passage for releasing carbonic acid solution is formed on one half of the side wall of the diffuser 6, and the passage for releasing carbonic acid solution is a combination of one row of small holes 9 and a plurality of rows of narrow gaps 8 (two combinations of small holes and narrow gaps); a plurality of channels for releasing carbonic acid solution on the same horizontal plane are uniformly arranged at a center included angle smaller than 180 degrees; two adjacent channels for releasing carbonic acid solution on the same horizontal plane are arranged at an acute central included angle to ensure that the outlet pressure of the carbonic acid solution is more than 3bar to be ejected and mixed with water to be treated. Through the small holes 9 and the narrow slits 8, the inlet pressure and the outlet pressure (ideal state) of the pressure mixed liquid (mixed liquid of carbonic acid solution with a certain pressure and micro bubbles) are identical, and are sprayed into water at a very high speed. Because the pressure drops, partial carbon dioxide gas can escape from the solution in the form of micro bubbles due to the pressure difference, so that the mixed solution of carbonic acid solution and micro bubbles is sprayed together to be mixed with water, and meanwhile, because the small holes 9 or the narrow gaps 8 on each row are positioned on the same vertical line and are uniformly arranged, the pressure difference exists between the side with holes of the diffuser 6 and the side without holes, and the pressure mixed solution forms vortex in the water, so that the acid-base neutralization reaction is further accelerated.

Compared with the Venturi nozzle in the prior art, the carbonic acid solution diffuser solves the problems of low use rate (dissolution rate) of carbon dioxide gas, noise, vibration, cavitation and the like; meanwhile, the application range of carbonic acid solution addition is wider, and the carbonic acid solution addition method can be applied to natural lakes, shallow ditches, shallow ponds, pipelines, liquid storage tanks and the like.

Example 2

As shown in fig. 2, the method for adding carbonic acid by using the small carbonic acid solution adding system in this embodiment is basically the same as the method for adding carbonic acid by using the small carbonic acid solution adding system in embodiment 1; the difference is that: the diffuser 6 is arranged in a water pool to be treated without water flow, and a plurality of passages for releasing carbonic acid solution are arranged on the side walls of both sides of the diffuser 6; the passages for releasing the carbonic acid solution are a combination of small holes and narrow gaps.

As shown in fig. 2, the diffuser 6 is arranged in a pool to be treated without water flow, and a plurality of circles of small holes and narrow slits (a row of small holes 9 and a row of narrow slits 8 are staggered) are formed on the whole cylindrical side wall of the diffuser 6, so that 360-degree throwing is realized.

The channels (small holes 9 and narrow slits 8) for releasing carbonic acid solution can generate back pressure of more than 3bar and enable the supersaturated carbonic acid solution to be sprayed into water to be treated in the water tank at an outlet pressure of more than 3bar, so that a pressure difference of more than 2bar is ensured between the outlet pressure of the diffuser and the pressure of the water to be treated.

The water outlet of the water pool which is to be treated and has no water flow is connected with the inlet of the water pump 4 through a reaction water pipeline 11 (the low pH effluent water treated by the carbonic acid adding system and the carbonic acid adding process is used as water for the water pump 4, namely reaction water).

The working principle of the method for adding carbonic acid by adopting the small carbonic acid solution adding system in the embodiment is as follows: the carbon dioxide gas gasified and heated to a temperature of 20 ℃ or higher and a pressure of 6bar or higher and the pressurized reaction water pressurized by the water pump 4 to a pressure of 3bar or higher form a gas-water mixture at the top of the reaction tank 5; the mixture of the gas and the water gradually forms saturated carbonic acid solution in the reaction tank 5; the saturated carbonic acid solution passes through a control valve 14 which is arranged on a carbonic acid solution pipeline 15 between the reaction tank 5 and the diffuser 6 and can precisely control the flow and the pressure to form supersaturated carbonic acid solution; the supersaturated carbonic acid solution is sprayed into the water in the water tank through the passages (small holes 9 and narrow slits 8) on the diffuser 6 for releasing the carbonic acid solution; a pH probe 7 is arranged at the water outlet of the water tank, the pH probe 7 is connected with a signal receiver, and the signal receiver is connected with the input end of the PLC controller; the output end of the PLC is connected with the control valve 14; the pH probe transmits signals to the signal receiver in real time, and the signal received by the signal receiver is processed by the PLC to control the opening of the control valve 14 so as to control the dosage of the carbonic acid solution, thereby achieving the pH value which the user wants to control.

Example 3

The method for adding carbonic acid by using the small carbonic acid solution adding system in this embodiment is basically the same as the method for adding carbonic acid by using the small carbonic acid solution adding system in embodiment 1; the difference is that: the carbonic acid solution pipeline 15 is a large-diameter pipeline larger than DN25, the carbonic acid solution releasing channel is a narrow slit, a row of narrow slits 8 are arranged in the middle, and a row of narrow slits 8 are arranged on two sides respectively.

Example 4

The method for adding carbonic acid by using the small carbonic acid solution adding system in this embodiment is basically the same as the method for adding carbonic acid by using the small carbonic acid solution adding system in embodiment 1; the difference is that: the electronic carburetor 2 is replaced by a fin heat exchanger, and the carbon dioxide gas is heated to a temperature of more than 20 ℃ through the fin heat exchanger; the carbonic acid solution pipeline 15 is a small-diameter pipeline with DN25, the carbonic acid solution releasing channel is a combination of small holes and narrow gaps, a row of narrow gaps 8 are arranged in the middle, and a row of small holes 9 are arranged on two sides.

Example 5

The method for adding carbonic acid by using the small carbonic acid solution adding system in this embodiment is basically the same as the method for adding carbonic acid by using the small carbonic acid solution adding system in embodiment 1; the difference is that: the liquid carbon dioxide reservoir 1 and the electronic vaporizer 2 are not replaced by dewar or steel cylinders. Carbon dioxide gas is released from a Dewar tank or a steel cylinder, heated to a temperature of more than 20 ℃ by a gas heater 3, and then the pressure is regulated to be more than 6bar by a pressure regulating valve group 10; carbon dioxide gas having a temperature of 20 ℃ or higher and a pressure of 6bar or higher is fed into the reaction tank 5 from the top of the tank through the gas pipe 12, and the air in the tank is discharged; meanwhile, low-pH water (low-pH water after being treated by adding carbonic acid) is pressurized to more than 3bar through a water pump 4, is sent into a reaction tank 5 from the top of the tank in a high-pressure mist form through a water pipeline 11, and keeps the pressure in the tank to be more than 3 bar; in the reaction tank 5, carbon dioxide gas is mixed with pressurized reaction water mist to form a gas-liquid mixture with certain pressure; because the contact area of the water mist and the carbon dioxide gas is large, and the carbon dioxide gas is rapidly dissolved in water and reacts to generate carbonic acid solution in a set pressure environment; along with the continuous feeding of carbon dioxide gas, when the pressure in the reaction tank reaches more than 6bar, the carbonic acid solution in the tank is converted into saturated carbonic acid solution; the saturated carbonic acid solution is conveyed to a control valve 14 capable of precisely controlling flow and pressure through a pipeline at the bottom of the reaction tank 5, the control valve 14 seals the saturated carbonic acid solution between the reaction tank 5 and the control valve 14, and the saturated carbonic acid solution becomes the supersaturated carbonic acid solution due to the continuous pressure in the reaction tank 5; opening the control valve 14, and conveying the supersaturated carbonic acid solution to the diffuser 6 through a pipeline by passing through a valve core in the control valve 14; the supersaturated carbonic acid solution is reversely sprayed into water through small holes and/or narrow gaps in the diffuser 6 to form a mixed solution of the high-concentration carbonic acid solution and a small amount of carbon dioxide micro-bubbles, the carbonic acid solution meets alkaline substances in the water and starts to perform acid-base neutralization reaction, and the small amount of carbon dioxide micro-bubbles are absorbed by water flow.

Claims

1. The method for adding carbonic acid by adopting the small carbonic acid solution adding system is characterized by comprising the following steps of:

(1) Establishing a small carbonic acid solution adding system; the small carbonic acid solution adding system comprises a reaction tank, a diffuser, a carbon dioxide gas pipeline and a reaction water pipeline; a water mist nozzle and a carbon dioxide gas nozzle are arranged on the top of the inner tank of the reaction tank; a water pump is arranged on the reaction water pipeline; the outlet of the water pump is connected with a water inlet and a water mist nozzle on the top of the reaction tank through a water pipeline; the carbon dioxide gas pipeline is provided with a pressure regulating valve group; the outlet of the pressure regulating valve group is connected with a carbon dioxide gas inlet and a carbon dioxide gas nozzle at the top of the reaction tank; the outlet at the bottom of the reaction tank is connected with the inlet of the diffuser; a control valve or a restriction orifice plate or an orifice capable of precisely controlling flow and pressure is arranged on a carbonic acid solution pipeline between an outlet at the bottom of the reaction tank and an inlet of the diffuser; the diffuser is arranged in the water to be treated; the diffuser is a hollow cylindrical object with one end open and the other end closed; a channel for releasing carbonic acid solution is formed on the cylindrical side wall of the diffuser; the passage for releasing the carbonic acid solution is a combination of a small hole and a narrow gap; the channel for releasing carbonic acid solution can generate back pressure of more than 3bar and enable supersaturated carbonic acid solution to be sprayed into water to be treated at an outlet pressure of more than 3bar, so that a pressure difference of more than 2bar is ensured between the outlet pressure of the diffuser and the pressure of the water to be treated; the back pressure of the diffuser is more than 3bar, and the pressure of the whole system is maintained to be more than 3bar;

The diffuser is arranged in a raw water pipeline with water flow to be treated and is positioned at the upstream of the water flow;

the state when the liquid passes through the narrow gap and the pressure is lower than 10bar is laminar flow, and the carbon dioxide is precipitated relatively little in the state;

(3) Carbon dioxide gas with certain temperature and certain pressure enters the tank top of the reaction tank through a gas pipeline, meanwhile, reaction water is pressurized to certain pressure through a water pump, is sent into the reaction tank from the tank top through a water pipeline in a high-pressure mist form, and the pressure in the tank is kept at certain pressure; in a reaction tankMixing carbon dioxide gas with pressurized reaction water to form a gas-liquid mixture with a certain pressure; because the contact area between the water mist and the carbon dioxide gas is large, and the carbon dioxide gas is rapidly dissolved in water and reacts to generate carbonic acid solution in a set pressure environment; along with the continuous feeding of carbon dioxide gas or along with the continuous feeding of water mist with certain pressure into the tank, the pressure in the tank is raised to a set pressure, and when the pressure in the reaction tank reaches a certain pressure, the carbonic acid solution in the reaction tank is converted into saturated carbonic acid solution; the saturated carbonic acid solution is conveyed to a control valve or a limiting orifice plate or an orifice hole capable of precisely controlling flow and pressure through a pipeline at the bottom of the reaction tank, the saturated carbonic acid solution is sealed between the reaction tank and the control valve or the limiting orifice plate or the orifice hole, and the saturated carbonic acid solution becomes supersaturated carbonic acid solution due to continuous pressure in the reaction tank and dissolution of carbon dioxide gas; the supersaturated carbonic acid solution is conveyed to the diffuser through a pipeline by a valve core or a flow limiting pore plate or an orifice in an opened control valve; the supersaturated carbonic acid solution is reversely sprayed into water through the passages, i.e. small holes and narrow gaps, designed on the diffuser for releasing the carbonic acid solution to form a mixed solution of the carbonic acid solution with high concentration and a small amount of carbon dioxide microbubbles, and the carbonic acid solution meets alkaline substances in the water and starts to perform acid-base neutralization reaction, or the carbonic acid solution and calcium ions or CaCO in the water ₃ The reaction is carried out, and a small amount of carbon dioxide micro bubbles are absorbed by water flow;

(4) The downstream of the water flow in the raw water pipeline is provided with a water quality on-line detector which is connected with a signal receiver, and the signal receiver is connected with the input end of the PLC; the output end of the PLC is connected with the control valve; the water quality online detector transmits signals to the signal receiver in real time, and the opening size of the control valve is controlled after the signals received by the signal receiver are processed by the PLC so as to control the feeding amount of the carbonic acid solution;

the diffuser is a hollow long cylindrical object with one closed end and one polygonal half of the cross section and the other circular arc, and a plurality of passages for releasing carbonic acid solution are arranged on one half side wall of one polygonal side of the diffuser; the passage for releasing the carbonic acid solution is a combination of one or more rows of small holes and one or more rows of narrow gaps; the diffuser is inserted into the raw water perpendicular to the water flow direction, one side of the diffuser with the combination of small holes and narrow gaps is opposite to the upstream of the water flow, so that the carbonic acid solution in the diffuser can be sprayed out reversely opposite to the water flow from the combination of small holes and narrow gaps;

the narrow gaps or small holes on each row are uniformly arranged on the same vertical line; a plurality of channels for releasing carbonic acid solution on the same horizontal plane are uniformly arranged at a center included angle smaller than 180 degrees; two adjacent channels for releasing carbonic acid solution on the same horizontal plane are arranged at an acute central included angle.

2. The method for adding carbonic acid by using a small carbonic acid solution adding system according to claim 1, wherein the inlet of the reaction water pipeline is connected with the water to be treated after the carbonic acid is added.

3. The method for adding carbonic acid by using a small carbonic acid solution adding system according to claim 1, wherein,

the small carbonic acid solution adding system also comprises a liquid carbon dioxide storage tank, an electronic vaporizer or a fin heat exchanger and a gas heater which are connected in sequence; or the small carbonic acid solution adding system also comprises a Dewar tank or a steel cylinder and a gas heater which are connected in sequence; the outlet of the gas heater is connected with the inlet of the carbon dioxide gas pipeline;

in the step (2), high-pressure low-temperature liquid carbon dioxide is stored in a liquid carbon dioxide storage tank, the liquid carbon dioxide is released from the bottom of the liquid carbon dioxide storage tank and is conveyed to an electronic vaporizer or a fin heat exchanger, and the electronic vaporizer or the fin heat exchanger continuously and quantitatively heats, gasifies and converts the liquid carbon dioxide into carbon dioxide gas; alternatively, the carbon dioxide gas is stored in a dewar or steel cylinder, and the carbon dioxide gas is released from the dewar or steel cylinder; the carbon dioxide gas is conveyed to a gas heater through a pipeline to be heated to a certain temperature, and then is regulated to a certain pressure through a pressure regulating valve group; the carbon dioxide gas is kept at a certain temperature and a certain pressure and is conveyed to the reaction tank through a carbon dioxide gas pipeline.

4. The method for adding carbonic acid by using a small carbonic acid solution adding system according to claim 3, wherein in the step (2), the carbon dioxide gas is conveyed to a gas heater through a carbon dioxide gas pipeline to be heated to a temperature above 20 ℃, and then the pressure is regulated to a pressure above 6bar through a pressure regulating valve group; the carbon dioxide gas is maintained at a temperature above 20 ℃ and a pressure above 6 bar.

5. The method for adding carbonic acid using a small-sized carbonic acid solution adding system according to claim 3, wherein in the step (3), carbon dioxide gas having a temperature of 20 ℃ or higher and a pressure of 6bar or higher is introduced into the top of the reaction tank through the gas pipe, and at the same time, the reaction water is pressurized to 3bar or higher by the water pump, and then is introduced into the reaction tank from the top of the tank through the water pipe in a high-pressure mist form, and the pressure in the tank is maintained at 3bar or higher.

6. The method for adding carbonic acid by adopting a small carbonic acid solution adding system according to claim 4, wherein the water quality on-line detector is a pH probe or a water hardness on-line detector or a turbidity on-line detector; the volume ratio of carbon dioxide gas having a temperature of 20 ℃ or higher and a pressure of 6bar or higher to reaction water is not lower than 1:40.

7. The method for adding carbonic acid by adopting a small carbonic acid solution adding system according to claim 1, wherein a cooling liquid coil pipe is arranged in the reaction tank, or a supplementary cooling water pipe for supplementing cooling water is arranged at the middle lower part of the reaction tank; the water mist nozzle at the top of the reaction tank is an industrial sonic nanoscale atomizer.