CN104498107A - Device and method for processing tar in coke oven crude gas - Google Patents

Abstract

The invention belongs to the technical field of tar catalytic cracking and waste heat recovery, and in particular relates to a device and method for treating tar in coke oven waste gas. The device of the present invention includes a catalytic cracking reactor, a catalyst regenerator, a gas-solid separator, an air preheater, a waste heat boiler and a feeding device; in the catalytic cracking reactor, high-temperature coke oven raw gas undergoes a cracking reaction under the action of a catalyst The small molecule combustible gas is generated, the catalyst and the solid particles produced by the reaction are carried by the gas into the gas-solid separator, and the coke oven gas after gas-solid separation enters the waste heat boiler, and the waste heat is further recovered, and the solid particles enter the catalyst regenerator. Under the action of the catalyst to achieve regeneration, the generated high-temperature flue gas preheats the air. The present invention makes full use of the tar and macromolecular hydrocarbons in the raw coke oven gas, converts them into small molecular combustible gases, improves the output of coke oven gas, and effectively recovers the coke oven gas high temperature wasted in the original process residual heat.

Description

A device and method for treating tar in coke oven raw gas

technical field

The invention belongs to the technical field of tar catalytic cracking and waste heat recovery, and in particular relates to a device and method for treating tar in coke oven waste gas.

Background technique

Tar is in gaseous form at high temperature, but it exists in liquid viscous form when the temperature is below 500°C, and it is easy to deposit in pipelines, instruments and other equipment, causing equipment blockage. The main components of the purified coke oven gas are H ₂ (53%~59%), CH ₄ (25%~30%), CO (about 6%), CO ₂ (about 2.5%) and a small amount of C _n H _m , N ₂ , etc., is a high-quality gas, but the tar content in raw coal gas before purification can reach 80~120g/m ³ , so the tar contained in it must be disposed of before coke oven gas purification. At present, in terms of purification treatment of coke oven raw gas, the process generally adopted at home and abroad is to introduce high-temperature raw gas (750~850°C) generated in the coke oven carbonization chamber into the gas collecting pipe through the riser pipe and bridge pipe, and pass through the bridge pipe. Spray ammonia water to remove macromolecular carbon-containing substances such as tar in raw gas, and coke oven gas is cooled to about 85°C at the same time. This process not only does not utilize the physical heat and chemical energy contained in the tar, but also wastes the high-temperature waste heat of the coke oven raw gas.

Contents of the invention

Aiming at the problems and defects in the prior art, the present invention provides a device and method for treating tar in coke oven raw gas, the purpose of which is to rationally utilize waste heat of coke oven raw gas, efficiently recycle tar and effectively increase coke oven gas output.

The device that realizes the object of the present invention comprises catalytic cracking reactor, catalyst regenerator, gas-solid separator, air preheater, waste heat boiler and feeding device, described catalytic cracking reactor lower end air inlet and coke oven carbonization chamber gas The outlet is connected, the side inlet is connected to the feeding device, the upper outlet is connected to the gas-solid separator; the upper outlet of the gas-solid separator is connected to the waste heat boiler, and the lower outlet is connected to the upper inlet of the catalyst regenerator Connection; the outlet at the lower end of the catalyst regenerator is connected to the feeding device, the air inlet at the side end is connected to the hot air outlet of the air preheater, and the flue gas outlet at the side end is connected to the high temperature flue gas inlet of the air preheater.

Wherein, the catalytic cracking reactor is a fluidized bed reactor, the fluidized medium is a tar cracking catalyst with a particle size of 20 to 500 microns, the catalyst enters the catalytic cracking reactor from the catalyst regenerator through the feeding device, and the coke oven carbonization chamber The high-temperature raw coal gas that comes out enters from the bottom of the catalytic cracking reactor to fluidize the catalyst particles.

The catalyst regenerator is a falling bed reactor or a moving bed reactor; when the catalyst regenerator is a falling bed reactor, the feed port at the upper end of the catalyst regenerator is connected with the gas-solid separator through a control valve, and the catalyst reacts in the catalytic cracking The regenerator moves from top to bottom by its own gravity and the effect of upward hot air; when the catalyst regenerator is a moving bed reactor, it consists of two moving beds, and the upper end of each moving bed feeds through the material of the reversing valve. The outlet and material inlet are connected to the lower outlet of the gas-solid separator, the lower outlet is connected to the feeding device through the control valve, the air inlet at the side end is connected to the air outlet of the reversing valve, the air inlet of the reversing valve is connected to the air The hot air outlet of the preheater is connected, and the flue gas outlet at the side end is connected with the high-temperature flue gas inlet of the air preheater through a control valve. During operation, one of the two moving beds provides catalyst for the catalytic cracking reactor, and the other introduces hot air through the into the catalyst bed to realize catalyst regeneration, and the two work alternately and interchangeably.

The method for processing the tar in the coke oven raw gas by using the above-mentioned device is carried out according to the following steps:

(1) Add the catalyst to the catalyst regenerator, close the feeding port after the feeding is completed, keep the temperature at 850~950°C, and control and adjust the feeding speed of the catalyst into the catalytic cracking reactor through the feeding device;

(2) Introduce high-temperature raw coke oven gas at 750~900°C into the catalytic cracking reactor to make the catalyst fluidized, and at the same time, macromolecular carbon-containing compounds such as tar gas contained in the raw gas fully contact with the catalyst to catalyze Cracking reaction, and then the coke oven gas carries the catalyst and the carbon particles produced by the cracking reaction into the gas-solid separator;

(3) After gas-solid separation, the coke oven gas enters the waste heat boiler to further recover waste heat, the generated steam is merged into the steam pipe network, the solid particles enter the catalyst regenerator, and cold air is introduced into the air preheater to heat up to 850°C After the above is passed into the catalyst regenerator, the solid particles are in contact with hot air, and the carbon deposits and coke on the surface of the solid particles, as well as the carbon particles mixed in the catalyst particles, are completely burned to realize the regeneration of the catalyst, and the temperature of the generated high-temperature flue gas At least 900°C, the flue gas outlet from the catalyst regenerator enters the high-temperature flue gas inlet of the air preheater to heat the cold air.

Wherein, when the adopted catalyst regenerator is a falling bed reactor, the solid particles returned to the catalyst regenerator contact with the incoming hot air during the falling process to generate combustion and CO _desorption reaction; when the adopted catalyst regenerator consists of When two moving bed reactors are composed, the catalyst is added to a moving bed of the catalyst regenerator, and the catalyst is sent into the catalytic cracking reactor through the feeding device through the moving bed, and the control valve and the reversing valve are adjusted to make the The hot air outlet of the air preheater is connected to the air inlet at the side end of another moving bed, and the solid particles separated by gas and solid are returned to another moving bed of the catalyst regenerator through the reversing valve, and the hot air is passed into the catalyst of the moving bed The bed layer is in contact with solid particles to generate combustion and _CO2 desorption reaction. When the catalyst in the moving bed supplied to the catalyst is discharged, adjust the control valve and reversing valve, and the two moving beds will exchange work, and the other moving bed will pass through. The feeding device supplies the catalyst to realize the continuous and stable operation of the device.

The catalyst is a CaO-based catalyst, which is CaO obtained by calcining calcium acetate or calcium hydroxide or CaO obtained by calcining calcium carbonate-containing ore.

The catalytic cracking reactor utilizes raw coke oven gas and the high-temperature heat of the catalyst itself to maintain the temperature in the catalytic cracking reactor at 750°C to 850°C.

Compared with prior art, feature and beneficial effect of the present invention are:

The CaO-based catalyst selected by the method of the present invention is not only used as a catalyst to catalyze the tar cracking reaction, but also absorbs the _CO2 produced by the cracking reaction and the original _CO2 in the raw coke oven gas, further promotes the process of the tar cracking reaction, and increases the output of coke oven gas and calorific value, the main reactions involved in the catalytic cracking reactor are:

Wherein, C _n H _m is an alkane, an alkene or an alkyne, m=2n+2, 2n-2 or 2n, and n is an integer ≥1.

The working temperature of the catalyst regenerator of the present invention is controlled above 900°C, and the combustion reaction between the hot air preheated by the air preheater and the carbon deposits and coke on the surface of the catalyst and the carbon particles mixed in the catalyst is the catalyst regenerator. Provides heat without the need for an additional heat source.

In the catalyst regenerator of the present invention, in addition to the combustion reactions of substances such as carbon deposits and coke, the higher operating temperature can make the catalyst that absorbs _CO in the catalytic cracking reactor desorb, i.e. _CaCO Cracking Reaction to achieve catalyst regeneration:

;

The present invention makes full use of the tar, macromolecular hydrocarbons, etc. in the raw coke oven gas that have been sprayed and purified by the original process, and converts them into small molecular combustible components, thereby increasing the output of coke oven gas and reducing operating costs. Input (such as the use of a large amount of ammonia water, etc.); the present invention makes the coke oven gas successively provide heat for the catalytic cracking reactor and the waste heat boiler, and effectively recovers the high-temperature waste heat of the coke oven gas that was wasted in the original process; in addition, the coke oven gas used in the present invention The catalyst can be regenerated and recycled, reducing investment costs.

Description of drawings

Fig. 1 is a process flow block diagram of the present invention;

Fig. 2 is the schematic diagram when the catalyst regenerator is a falling bed reactor in the device for processing tar in coke oven raw gas of the present invention;

Fig. 3 is one of working schematic diagrams when the catalyst regenerator is a moving bed reactor in the device for processing tar in coke oven raw gas of the present invention;

Fig. 4 is the second schematic diagram of the working operation when the catalyst regenerator is a moving bed reactor in the device for processing tar in coke oven raw gas of the present invention;

Among them: 1: catalytic cracking reactor; 2: gas-solid separator; 3: control valve; 3-1: first control valve; 3-2: second control valve; 3-3: third control valve; 3- 4: fourth control valve; 4: catalyst regenerator; 4-1: first moving bed; 4-2: second moving bed; 5: feeding device; 6: waste heat boiler; 7: air preheater; 8 -1: the first reversing valve; 8-2 the second reversing valve; 9: the material inlet of the reversing valve; 10-1: the first material outlet of the reversing valve; 10-2: the second material outlet of the reversing valve; 11: air inlet of reversing valve; 12-1: first air outlet of reversing valve; 12-2: second air outlet of reversing valve;

in: Represents the flow direction of raw coke oven gas; represents the flow direction of the catalyst; in the catalyst regenerator Represents the direction of flow of hot air.

Detailed ways

The device for realizing the object of the present invention comprises a catalytic cracking reactor 1, a catalyst regenerator 4, a gas-solid separator 2, an air preheater 7, a waste heat boiler 6 and a feeding device 5, and the lower end of the catalytic cracking reactor 1 has an intake air The outlet is connected to the gas outlet of the coke oven carbonization chamber, the side feed port is connected to the feeding device 5, the upper end of the outlet is connected to the gas-solid separator 2; the upper end of the gas-solid separator 2 is connected to the waste heat boiler 6, and the lower end is connected to the The feed port is connected to the upper end feed port of the catalyst regenerator 4; the lower end discharge port of the catalyst regenerator 4 is connected to the feeding device 5, the air inlet at the side end is connected to the hot air outlet of the air preheater 7, and the flue gas at the side end The outlet is connected with the high-temperature flue gas inlet of the air preheater 7 .

Wherein, described catalytic cracking reactor 1 is a fluidized bed reactor, and fluidized medium is the tar cracking catalyst of particle diameter 20～500 microns, and catalyst enters catalytic cracking reactor 1 by catalyst regenerator 4 through feeding device 5, The high-temperature raw gas from the coking chamber of the coke oven enters from the bottom of the catalytic cracking reactor 1 to fluidize the catalyst particles.

The catalyst regenerator 4 is a falling bed reactor or a moving bed reactor;

As shown in Figure 2, when the catalyst regenerator 4 is a falling bed reactor, the upper outlet of the catalyst regenerator 4 is connected with the gas-solid separator 2 through the control valve 3, and the catalyst is in the catalytic cracking reactor 1 by its own gravity And the action of upward hot air moves from top to bottom;

As shown in Figure 3, when the catalyst regenerator 4 is a moving bed reactor, it consists of two moving beds 4-1 and 4-2, and the upper end feed port of each moving bed passes through the first reversing valve 8-1 The first material outlet 10-1 of the reversing valve and the second material outlet 10-2 of the reversing valve, the material inlet 9 are connected with the lower end discharge port of the gas-solid separator 2, and the lower end discharge port passes through the third control valve 3- 3 and the fourth control valve 3-4 are connected to the feeding device, and the air inlet at the side end is connected to the first air outlet 12-1 of the reversing valve 8-2 and the second air outlet 12-2 of the reversing valve The air inlet 11 of the reversing valve is connected to the hot air outlet of the air preheater 7, and the flue gas outlet at the side end passes through the first control valve 3-1, the second control valve 3-2 and the high temperature smoke of the air preheater 7. The gas inlet is connected. When working, one of the two moving beds 4-1 and 4-2 provides catalyst for the catalytic cracking reactor 1, and the other introduces hot air to realize catalyst regeneration. The two work alternately and interchangeably.

The present invention also provides a method for treating tar in coke oven raw gas. The method of the present invention will be further described below in conjunction with the accompanying drawings and specific examples.

Table 1 Composition of raw coke oven gas

In the embodiment of the present invention, a coke oven with a coke output of 100t/h is taken as the object, and the raw coke oven gas produced per hour is 42000Nm ³ , and the composition of the raw gas is shown in Table 1.

The tar cracking catalyst uses a CaO-based catalyst, calcines calcium acetate, or calcium hydroxide, or other calcium oxide precursors at a temperature ≥ 900 ° C, and the obtained calcium oxide is crushed to a particle size of 20 to 500 microns as a cracking catalyst.

Example 1

When the catalyst regenerator adopts the form of falling bed, referring to Fig. 1 and 2, the specific implementation steps are:

(1) Add the catalyst to the catalyst regenerator 4, close the feeding port after the feeding is completed, keep the temperature at 850~950°C, and control the feeding speed of the catalyst into the catalytic cracking reactor through the feeding device 5 to be 2~3kg /s;

(2) Introduce high-temperature raw coke oven gas at 750-900°C into the catalytic cracking reactor 1 to make the catalyst fluidized, and at the same time, the tar gas, crude benzene, C ₁₀ H ₈ contained in the raw gas and the catalyst Fully contacted, small molecular combustible gases such as H ₂ , CO, CH ₄ , C _n H _m produced by catalytic cracking reactions will flow into the coke oven gas to increase gas production, and at the same time, CaO will absorb CO ₂ produced by cracking reactions and coke oven waste The original CO ₂ in the gas increases the concentration of combustible gas in the gas, thereby increasing the calorific value of the gas, and then the coke oven gas carries the catalyst and the carbon particles produced by the cracking reaction into the gas-solid separator 2;

(3) After gas-solid separation, the coke oven gas enters the waste heat boiler 6 to further recover waste heat, the generated steam is merged into the steam pipe network, and the solid particles are returned to the catalyst regenerator 4, and cold air is introduced into the air preheater 7 to heat up to After the temperature is above 850°C, it is passed into the catalyst regenerator 4, and the solid particles returned to the catalyst regenerator 4 are in contact with the incoming hot air during the falling process to cause combustion and _CO2 desorption reaction, and the carbon deposits and coke on the surface of the solid particles The carbon particles and the carbon particles mixed in the catalyst particles are completely burned to realize the regeneration of the catalyst, and the temperature of the generated high-temperature flue gas is at least 900°C. The high-temperature flue gas enters the air preheater 7 from the flue gas outlet of the catalyst regenerator 4 In the inlet, it is used to heat the cold air.

When the catalyst regenerator adopts the form of moving bed, referring to Fig. 1, Fig. 3 and Fig. 4, the specific steps are:

(1) Add the catalyst to the first moving bed 4-1, close the feeding port after feeding, keep the temperature at 850~950°C, close the first control valve 3-1 and the third control valve 3-3, open the second The second control valve 3-2 and the fourth control valve 3-4, adjust the first reversing valve 8-1, make the material inlet 9 of the reversing valve connect with the second material outlet 10-2 of the reversing valve, adjust the second reversing valve To the valve 8-2, the air inlet 11 of the reversing valve is connected with the second air outlet 12-2 of the reversing valve, and the first moving bed 4-1 controls the feeding of the catalyst into the catalytic cracking reactor by the feeding device 5 Material speed is 2~3kg/s;

(2) Introduce high-temperature raw coke oven gas at 750-900°C into the catalytic cracking reactor 1 to make the catalyst fluidized, and at the same time, the tar gas, crude benzene, C ₁₀ H ₈ contained in the raw gas and the catalyst Fully contacted, small molecular combustible gases such as H ₂ , CO, CH ₄ , C _n H _m produced by catalytic cracking reactions will flow into the coke oven gas to increase gas production, and at the same time, CaO will absorb CO ₂ produced by cracking reactions and coke oven waste The original CO ₂ in the gas increases the concentration of combustible gas in the gas, thereby increasing the calorific value of the gas, and then the coke oven gas carries the catalyst and the carbon particles produced by the cracking reaction into the gas-solid separator 2;

(3) After gas-solid separation, the coke oven gas enters the waste heat boiler 6 to further recover waste heat, and the generated steam is merged into the steam pipe network, and the solid particles enter the second moving bed 4-2 through the first reversing valve 8-1 , cold air is introduced into the air preheater 7, and after being heated to above 850°C, it is passed into the catalyst bed layer of the first moving bed 4-1, so that the carbon deposits, coke on the surface of the catalyst and the carbon particles mixed in the catalyst The combustion is completely exhausted, and at the same time, the catalyst adsorbing CO ₂ in the catalytic cracking reactor 1 undergoes CO ₂ desorption reaction to realize the regeneration of the catalyst, and the temperature of the high-temperature flue gas generated is at least 900°C. The gas outlet and the second control valve 3-2 enter the high-temperature flue gas inlet of the air preheater 7 for heating the cold air;

When the catalyst discharge in the first moving bed 4-1 is complete, adjust the flow direction of the first reversing valve 8-1, the second reversing valve 8-2 and the first control valve 3-1, the second control valve 3-2. The switch state of the third control valve 3-3 and the fourth control valve 3-4, that is, the reversing valve material inlet 9 of the first reversing valve 8-1 and the first material outlet 10-1 of the reversing valve connected, the reversing valve air inlet 11 of the second reversing valve 8-2 is connected with the first air outlet 12-1 of the reversing valve, the first control valve 3-1 and the third control valve 3-3 are opened, and the The second control valve 3-2 and the fourth control valve 3-4 make the second moving bed 4-2 provide catalyst for catalytic cracking reactor 1, and introduce hot air in the first moving bed 4-1 to realize catalyst regeneration, the second The first moving bed 4-1 and the second moving bed 4-2 work alternately to realize the continuous and stable operation of the system.

Claims (7)

1. process the device that coal oven dithio-gas is coal-tar middle oil, it is characterized in that comprising catalytic cracking reaction device, catalyst regenerator, gas-solid separator, air preheater, waste heat boiler and feeding device; Described catalytic cracking reaction device lower end inlet mouth is connected with coke furnace carbonization chamber gas exit, and side opening for feed is connected with feeding device, and upper end discharge port is connected with gas-solid separator; The air outlet, upper end of gas-solid separator is connected with waste heat boiler, and lower end discharge port is connected with the upper end opening for feed of catalyst regenerator; The lower end discharge port of catalyst regenerator is connected with feeding device, and the gas inlet of side is connected with the hot air outlet of air preheater, and the exhanst gas outlet of side is connected with the high-temperature flue gas import of air preheater.

2. according to claim 1ly a kind ofly process the coal-tar middle oil device of coal oven dithio-gas, it is characterized in that described catalytic cracking reaction device is fluidized-bed reactor, fluidizing medium is the tar cracking catalyst particle of particle diameter 20 ~ 500 microns, catalyzer enters catalytic cracking reaction device by feeding device by catalyst regenerator, coke furnace carbonization chamber high temperature raw gas is out entered by catalytic cracking reaction device lower end inlet mouth, makes granules of catalyst form fluidization.

3. according to claim 1ly a kind ofly process the coal-tar middle oil device of coal oven dithio-gas, it is characterized in that described catalyst regenerator is whereabouts bed bioreactor or moving-burden bed reactor;

When catalyst regenerator is whereabouts bed bioreactor, the upper end opening for feed of catalyst regenerator is connected with gas-solid separator by control valve, and catalyzer moves from top to bottom by the effect of self gravitation and up warm air in catalytic cracking reaction device;

When catalyst regenerator is moving-burden bed reactor, be made up of two moving-beds, the upper end opening for feed of each moving-bed is by the material outlet of reversing valve, material inlet is connected with the lower end discharge port of gas-solid separator, lower end discharge port is connected with feeding device by control valve, the gas inlet of side is connected with the air vout of reversing valve, the air intlet of reversing valve is connected with the hot air outlet of air preheater, the exhanst gas outlet of side is connected with the high-temperature flue gas import of air preheater by control valve, during work, two moving-beds one provide catalyzer for catalytic cracking reaction device, another is introduced warm air and passes into beds, realize catalyst regeneration, the two alternately exchanges work.

4. adopt the method that device process coal oven dithio-gas according to claim 1 is coal-tar middle oil, it is characterized in that carrying out according to following steps:

(1) join in catalyst regenerator by catalyzer, fed in raw material rear enclosed charging opening, keeps temperature to be 850 ~ 950 DEG C, passed into the delivery rate in catalytic cracking reaction device by feeding device regulating and controlling catalyzer;

(2) in catalytic cracking reaction device, pass into the high temperature coke oven raw gas of 750 ~ 900 DEG C, catalyzer is made to form fluidization, the macromole carbon compounds such as the tar gas simultaneously contained in raw gas fully contact with catalyzer, catalytic cracking reaction occurs, and then coke-oven gas carries the carbon granule that catalyzer and scission reaction produce and enters gas-solid separator;

(3) after gas solid separation, coke-oven gas enters the further recovery waste heat of waste heat boiler, the steam produced is incorporated in steam pipe system, solid particulate enters in catalyst regenerator, freezing air is introduced in air preheater, being heated to after more than 850 DEG C passes in catalyst regenerator, solid particulate and hot air, the carbon distribution of solid particles surface, coke-like thing and be mixed in charcoal particle burning in granules of catalyst totally, realize the regeneration of catalyzer, the high-temperature flue-gas produced is at least 900 DEG C, the high-temperature flue gas import of air preheater is entered into from the exhanst gas outlet of catalyst regenerator, for heating cold air.

5. according to claim 4ly a kind ofly process the coal-tar middle oil method of coal oven dithio-gas, when it is characterized in that working as adopted catalyst regenerator is whereabouts bed bioreactor, the solid particulate of return catalizer revivifier occurs to burn and CO with the hot air passed in dropping process ₂desorption reaction;

When the catalyst regenerator adopted is made up of two moving-burden bed reactors, catalyzer is joined in a moving-bed of catalyst regenerator, through feeding device, catalyzer is sent in catalytic cracking reaction device by this moving-bed, by adjusting control valve and reversing valve, the hot air outlet of air preheater is connected with the gas inlet of another moving-bed side, through the solid particulate of gas solid separation by another moving-bed of reversing valve return catalizer revivifier, warm air is passed into the beds of moving-bed and solid particle contacts occurs to burn and CO ₂desorption reaction, after the catalyzer discharge in the moving-bed of supply catalyzer, adjustment control valve and reversing valve, two moving-bed exchange work, supply catalyzer by another moving-bed by feeding device, the continuous and steady operation of implement device.

6. according to claim 4ly a kind ofly process the coal-tar middle oil method of coal oven dithio-gas, it is characterized in that described catalyzer is that the CaO of particle diameter 20 ~ 500 microns is catalyst based, is calcine obtained CaO or the obtained CaO of ore calcination calciferous by calcium acetate or calcium hydroxide.

7. according to claim 4ly a kind ofly process the coal-tar middle oil method of coal oven dithio-gas, it is characterized in that described catalytic cracking reaction device utilizes coal oven dithio-gas and catalyzer self heat of high temperature to maintain in catalytic cracking reaction device temperature at 750 ~ 850 DEG C.