CN107488770A - A kind of Coal Grinding System of Pci humidification process and device - Google Patents

Abstract

The invention belongs to the field of metallurgy, and in particular relates to a humidification process and device for a coal-injection pulverization system of a blast furnace. By installing a humidifying device, atomized water is sprayed into the dry gas to be entered into the coal mill to cool down the dry gas and achieve the purpose of reducing the concentration of oxygen components in the dry gas. The present invention can effectively solve the problem of production shutdown due to excessive oxygen content in the dry gas in the existing flue gas self-circulating pulverizing system process, which is conducive to stable production and elimination of potential safety hazards, and not only has the advantages of significant economic benefits, safety and reliability , but also has the characteristics of simple process, mature and reliable technology, easy realization, and low investment cost.

Description

A humidification process and device for blast furnace coal injection pulverization system

technical field

The invention belongs to the field of metallurgy, and in particular relates to a humidification process and device for a coal-injection pulverization system of a blast furnace.

Background technique

Blast furnace coal injection is an important energy-saving technology that replaces coke with coal in the blast furnace ironmaking process and changes the fuel structure of the blast furnace. It plays an important role in alleviating the shortage of coking coal resources, reducing the cost of pig iron and reducing environmental pollution, and has significant economic, environmental and social benefits.

Blast furnace coal injection pulverization system is the key link of blast furnace coal injection technology. At present, there are mainly two technologies in China: flue gas direct exhaust pulverization system and flue gas self-circulation pulverization system. The flue gas direct exhaust pulverizing system is the mainstream technology adopted by the blast furnace coal injection pulverizing system at present, but the flue gas self-circulation pulverizing system process can effectively solve the high investment in waste gas pipelines caused by the fact that the blast furnace coal injection workshop is far away from the blast furnace hot blast stove system , Insufficient amount of exhaust gas from hot blast stoves or the inability to use the flue gas direct exhaust pulverizing system due to the limitation of the ironworks site, so it has been gradually popularized and applied in domestic iron and steel plants.

The flue gas self-circulation pulverizing system is a kind of drying gas with a temperature between 200°C and 300°C and an oxygen content of ≤8% by mixing high-temperature flue gas generated by burning blast furnace gas in a flue gas furnace and self-circulating flue gas. Coal pulverizer is the process of grinding coal powder. Among them, the high-temperature flue gas generated by burning blast furnace gas in the flue gas furnace is mainly composed of CO ₂ and N ₂ , and the temperature is 900°C to 1100°C. It has the characteristics of high temperature and low oxygen content (≤2%), and is a good choice. High-temperature, inert heating gas accounts for 30% to 45% of the dry gas; self-circulating flue gas is the tail gas of the inert dry gas after the gas-powder separation is completed by equipment such as bag filter and main exhaust fan, and its main components are Water vapor, CO ₂ and N ₂ , with a temperature of about 85°C, have the characteristics of low temperature and low oxygen content (10%-12%), and are good temperature-regulating media for high-temperature flue gas, and their proportion in dry gas is 55% to 70%. One of the key indicators of this process is the oxygen content of the system's inert drying gas, which has become a limiting factor for the normal and safe production of this process. According to the mandatory provisions of the national standard "Code for Design of Blast Furnace Injection Coal Pulverized Engineering" (GB50607-2010): the maximum allowable oxygen content of the inert dry gas under system conditions is ≤12%. The pulverized coal may explode due to excessive oxygen content, ensuring the safe operation of the system and preventing accidents such as casualties.

However, because the flue gas self-circulation pulverizing system process uses part of the system tail gas (self-circulation flue gas) as the gas source of the inert drying gas of the coal mill, and the concentration of oxygen components in the drying gas is gradually enriched due to recycling, so It is easy to produce the problem that the dry gas has a high oxygen content. At the same time, due to the unavoidable air leakage of different degrees (air leakage rate > 8%) in equipment such as coal mills, coal feeders, and bag powder collectors in the pulverization system, as well as at the pipe connection flanges, the air leakage rate is further exacerbated. Oxygen content of dry gas rises. Therefore, in production, the oxygen content of dry gas exceeds the standard and the shutdown problem often occurs, which affects the normal production of the enterprise. Therefore, reducing the oxygen content of the inert dry gas in the flue gas self-circulating pulverizing system is very important to ensure the normal and safe production of enterprises and reduce their economic losses, but there are few reports on the technical solutions to this problem in the industry.

Contents of the invention

In view of this, the object of the present invention is to provide a blast furnace coal-injection pulverization system humidification process and device to solve the problem of excessive oxygen content in the inert dry gas of the existing flue gas self-circulating pulverization system process.

In order to achieve the above purpose, the present invention provides the following technical solutions: a humidification process for the blast furnace coal injection pulverization system, at least one humidification device is connected to the dry gas pipeline between the flue gas outlet of the flue gas furnace and the flue gas inlet of the coal mill to control the humidification The device sprays the injection amount of atomized water into the drying gas pipeline, increases and adjusts the amount of flue gas generated by the combustion of blast furnace gas in the flue gas furnace, and reduces and adjusts the amount of self-circulating flue gas.

Further, the atomized water is generated by atomizing liquid industrial water, and the atomized particle size is 1 μm to 5 μm.

Further, the water quality of liquid industrial water requires that the suspended matter content is ≤50mg/L, the pH value is 6.5-9, and the carbonate hardness is ≤140mg/L.

Further, atomized water is pressurized and sprayed into the drying gas pipeline.

A humidification device for a blast furnace coal injection pulverization system, including a water supply device, an atomization device, and a pressurizer connected in sequence through pipelines, and the pressurizer is connected to the flue gas outlet of the flue gas furnace and the coal mill smoke through the humidification pipeline. The dry gas pipelines between the gas inlets are connected.

Further, it also includes a flow sensor and a flow regulating valve sequentially arranged between the water supply device and the atomizing device.

Further, the humidifying device has multiple paths, which are sequentially connected in parallel to the dry gas pipeline.

The beneficial effects of the present invention are:

1) It can effectively solve the problem of production shutdown due to excessive oxygen content in the dry gas in the existing flue gas self-circulating pulverizing system process, which is conducive to stable production and has significant economic benefits;

2) It can realize real-time regulation, so that the oxygen content of the inert dry gas in the system can be strictly controlled within 12% of the national standard value, which effectively guarantees the safety of the system operation and eliminates potential safety hazards, so it has the advantages of safety and reliability;

3) The flue gas self-circulating pulverizing system adopts a humidification process, which is simple, mature and reliable, and easy to implement;

4) The composition of the humidifying device is simple, the existing equipment can be improved, and the investment cost is low.

Description of drawings

In order to make the purpose, technical scheme and beneficial effect of the present invention clearer, the present invention provides the following drawings for illustration:

Figure 1 is a schematic diagram of the present invention.

detailed description

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in the figure, the blast furnace coal injection pulverization system includes a raw coal bunker 11, a coal feeder 10, a flue gas furnace 1, a coal mill 9, a bag powder collector 12 and a main exhaust fan 13. The blast furnace coal injection pulverization system in this embodiment has a humidification device, including a water supply device 3, an atomization device 6, and a pressurizer 7 connected in sequence through pipelines. The pressurizer 7 is connected to the fume The dry gas pipeline 2 between the flue gas outlet of the gas furnace 1 and the flue gas inlet of the coal mill 9 is connected. The atomizing device 6 can generate atomized water from the liquid industrial water in the water supply device 3 , and the pressurizer 7 can pressurize the atomized water and introduce it into the drying gas pipeline 2 .

This embodiment also includes a flow sensor 4 and a flow regulating valve 5 sequentially arranged between the water supply device 3 and the atomizing device 6 . The flow sensor 4 and the flow regulating valve 5 are used to realize flow cascade control loop feedback, which can monitor and adjust the flow in real time, so as to achieve the purpose of controlling the injection amount of atomized water.

As a further improvement of the above solution, the humidification device has multiple channels, which are sequentially connected to the dry gas pipeline 2 in parallel. It can be used as a backup cooling circuit, and can be turned on at the same time to achieve precise regulation.

The specific process is: after the liquid industrial water in the water supply device 3 passes through the atomization device 6 to generate atomized water, it is led to the pressurizer 7 through the pipeline, pressurized to the pressure required by the process, and then the mist is discharged through the humidification pipeline 8. The chemical water is introduced into the drying gas pipeline 2, and the humidification amount is adjusted by the flow regulating valve 5 and the flow sensor 4, so as to obtain the low oxygen content drying gas that meets the process requirements. The qualified dry gas is introduced into the coal mill 9 by means of the suction force of the main exhaust fan 13 in the pulverizing system. The coal mill 9 grinds the raw coal from the raw coal bunker 11 and the coal feeder 10, and the dry gas Qualified pulverized coal is dried and transported, and pulverized coal with qualified quality is sent into the bag powder collector 12 through the conveying pipeline, and the gas-powder separation is carried out through the bag powder collector 12, and the pulverized coal enters the injection system, and the drying gas passes through the main The exhaust fan 13 discharges to the high altitude, and part of the exhaust gas enters the flue gas furnace 1 for recycling.

In the humidification process of the blast furnace coal injection pulverization system, at least one humidification device is connected to the dry gas pipeline 2 between the flue gas outlet of the flue gas furnace 1 and the flue gas inlet of the coal mill 9, and the humidification device is controlled to spray into the dry gas pipeline 2 The injection amount of atomized water increases and adjusts the amount of flue gas generated by the combustion of blast furnace gas in the flue gas furnace 1, and reduces and adjusts the amount of self-circulating flue gas.

Specifically, the atomized water is produced by atomizing liquid industrial water through the atomizing device 6 , pressurized by the pressurizer 7 to the pressure required by the process, and then sprayed into the dryer pipeline through the humidifying pipeline 8 . The atomized particle size is controlled between 1 μm and 5 μm. The water quality of liquid industrial water requires that the suspended matter content is ≤50mg/L, the pH value is 6.5-9, and the carbonate hardness is ≤140mg/L.

The process reduces the amount of self-circulating flue gas in the drying gas by passing the fine-grained atomized water with a particle size of 1 μm to 5 μm into the drying gas, thereby achieving the purpose of reducing the concentration of oxygen components in the drying gas. The specific reasons are: on the one hand, because the atomized water has the characteristics of small single particle size, large surface area, easy vaporization, and fast heat absorption, it can quickly take away the heat of the drying gas, thereby reducing the temperature of the drying gas. Due to the temperature difference caused by the vaporization of atomized water, the flue gas furnace needs to burn more blast furnace gas to increase the supply of high-temperature flue gas, and at the same time reduce the amount of self-circulating flue gas to maintain the temperature of the drying gas to meet the process requirements; on the other hand, Since the atomized water changes from a liquid state to a gaseous state due to heat absorption and vaporization, the volume ratio of water vapor in the drying gas is increased, and the amount of self-circulating flue gas in the drying gas is reduced, thereby diluting the concentration of oxygen components in the drying gas accordingly. , reducing the volume ratio of the oxygen component in the drying gas, thereby achieving the purpose of reducing the oxygen content of the drying gas.

Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that it can be described in terms of form and Various changes may be made in the details without departing from the scope of the invention defined by the claims.

Claims (7)

1. A kind of 1. Coal Grinding System of Pci humidification process, it is characterised in that：Enter in combustion gas furnace exhanst gas outlet and coal pulverizer flue gas Humidification device all the way is at least connected in drying feed channel between mouthful, control humidification device is blown atomized water into dry feed channel Injection amount, increase and adjust the exhaust gas volumn that blast furnace gas combustion generates in combustion gas furnace, reduce and adjust self-loopa exhaust gas volumn.
2. 2. Coal Grinding System of Pci humidification process according to claim 1, it is characterised in that：Atomized water is liquid-state industrial Water atomization generates, and atomizing particle size is 1 μm~5 μm.
3. 3. Coal Grinding System of Pci humidification process according to claim 2, it is characterised in that：Liquid-state industrial water water quality will Suspension content≤50mg/L is sought, pH value is 6.5~9, carbonate hardness≤140mg/L.
4. 4. Coal Grinding System of Pci humidification process according to claim 1, it is characterised in that：Atomized water pressurization sprays into dry In pathogenic dryness pipeline.
5. 5. a kind of humidification device for being applied to the Coal Grinding System of Pci humidification process as described in any one of Claims 1 to 4, It is characterized in that：Including the water supply installation, atomising device and pressurizer being sequentially connected by pipeline, the pressurizer passes through humidification Pipeline is connected with the drying feed channel being connected between combustion gas furnace exhanst gas outlet and coal pulverizer smoke inlet.
6. 6. Coal Grinding System of Pci humidification device according to claim 5, it is characterised in that：Also include being successively set on Flow sensor and flow control valve between water supply installation and atomising device.
7. 7. Coal Grinding System of Pci humidification device according to claim 6, it is characterised in that：The humidification device has more Road, it is connected in parallel on successively in dry feed channel.