Semi-coke tail gas treatment system

Abstract

The utility model relates to a semi-coke tail gas treatment system which comprises a purifier, a fan, a preheater, a reactor, a heat exchanger and a gas-liquid separator which are sequentially arranged in the flowing direction of semi-coke tail gas, the purifier is used for removing impurities influencing the activity of an oxygen carrier in the semi-coke tail gas, and the fan is used for pressurizing the purified semi-coke tail gas and then feeding the pressurized semi-coke tail gas into the preheater for heating; a pipeline between the preheater and the fan is communicated with a nitrogen pipeline and a water vapor pipeline, and the reactor is used for accommodating iron oxide, so that semi-coke tail gas heated by the preheater enters the reactor and then reacts with the iron oxide to generate ferrous oxide; the nitrogen pipeline is used for guiding nitrogen to sequentially purge the preheater, the reactor, the heat exchanger and the gas-liquid separator after the reaction of the semi-coke tail gas and iron oxide, and the water vapor pipeline is used for guiding water vapor to enter the reactor and react with ferrous oxide to generate hydrogen after nitrogen purging; the technical problems that methane and carbon monoxide in semi-coke tail gas cannot be utilized, and the heat value of the semi-coke tail gas is low are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of blue coke tail gas, in particular to a blue coke tail gas treatment system. Background Art

[0002] Semi-coke, also known as semi-coke, is a solid substance with high fixed carbon content produced by medium-low temperature dry distillation process using Jurassic non-caking coal and weakly caking coal as raw materials. It is named because it produces a blue flame when burning. While producing semi-coke, semi-coke tail gas and coal tar are by-products. The composition of semi-coke tail gas varies depending on the coal quality and production process. Conventional semi-coke tail gas components include hydrogen (20%-28%), methane (7%-10%), carbon monoxide (14%-18%), nitrogen (37%-43%), oxygen (0.1%-0.5%), and impurities such as tar, dust, and sulfide. Using semi-coke tail gas as raw material to produce high-purity hydrogen can not only solve the pollution problem of semi-coke tail gas emission and combustion, but also reduce the waste of a large amount of coke resources. It is an economical and environmentally friendly measure for the processing and utilization of semi-coke tail gas, and has obvious competitive advantages.

[0003] The current hydrogen separation and purification technology and pressure swing adsorption (PSA) are widely used gas separation technologies. Taking molecular sieve as an example, the principle is to separate gas mixtures by using the difference in the "adsorption" performance of molecular sieves to different gas molecules. Using pressure swing adsorption to extract hydrogen from semi-coke tail gas can not only effectively solve the resource utilization of semi-coke tail gas, but the total amount of methane and carbon monoxide equivalent to the hydrogen content cannot be used, and the calorific value of semi-coke tail gas is low. Utility Model Content

[0004] The utility model provides a blue coke tail gas treatment system to solve the technical problems that methane and carbon monoxide in the blue coke tail gas cannot be utilized and the calorific value of the blue coke tail gas is low.

[0005] In order to solve the above problems, the utility model adopts the following technical solutions:

[0006] A semi-coke tail gas treatment system comprises a purifier, a fan, a preheater, a reactor, a heat exchanger and a gas-liquid separator which are arranged in sequence along the flow direction of the semi-coke tail gas, wherein the purifier is used to remove impurities which affect the activity of oxygen carriers in the semi-coke tail gas sent from a main pipeline, the fan is used to pressurize the purified semi-coke tail gas and send it into the preheater for heating, the pipeline between the preheater and the fan is connected with a nitrogen pipeline and a water vapor pipeline, the reactor is used to contain iron oxide so that the semi-coke tail gas heated by the preheater enters the reactor and reacts with the iron oxide to generate ferrous oxide; the nitrogen pipeline is used to guide the nitrogen to sequentially purge the preheater, the reactor, the heat exchanger and the gas-liquid separator after the semi-coke tail gas reacts with the iron oxide, and the water vapor pipeline is used to guide the water vapor into the reactor after the nitrogen purge and react with the ferrous oxide to generate hydrogen.

[0007] The beneficial effects are: a two-step reaction is carried out in the reactor, in the first step, the methane, carbon monoxide and hydrogen in the lignite tail gas seize the oxygen element in the oxygen carrier, and reduce the iron oxide to ferrous oxide; then the preheater, reactor, heat exchanger and gas-liquid separator are purged to carry out the second step; in the second step, water vapor oxidizes the ferrous oxide to form iron oxide and generates high-purity hydrogen, and the methane and carbon monoxide gases in the lignite tail gas are utilized, the hydrogen content in the treated lignite tail gas is significantly increased, and the calorific value of the lignite tail gas is greatly improved.

[0008] Furthermore, the gas-liquid separator is connected to a gas detector, and the gas detector is used to detect the composition of the gas discharged from the gas-liquid separator.

[0009] The beneficial effect is: after the first step of reaction, the gas detector can detect the reaction degree of the lignite tail gas, and after the second step of reaction, the gas detector can detect the concentration of hydrogen, which is convenient for technicians to control the reaction situation inside the reactor in real time and make corresponding adjustments in time.

[0010] Furthermore, the pipeline between the fan and the preheater is connected to a gas detector, and the gas detector is used to detect the composition of the lignite tail gas after being purified by the purifier.

[0011] The beneficial effect is that before the first step of the reaction, the impurities in the semi-coke tail gas are removed before being fed into the reactor, thereby preventing the impurities in the semi-coke tail gas from affecting the activity of the filler in the reactor.

[0012] Furthermore, the air outlet of the fan is connected to pipeline one, pipeline one is connected to pipeline two and pipeline three respectively through three-way one, and pipeline two and pipeline three are used to connect to the air inlet of the preheater.

[0013] The beneficial effects are: the lignite tail gas enters the preheater in two ways, and the flow rate and velocity of each gas can be independently controlled, so that the gas is more evenly distributed inside the preheater, reducing local overheating or overcooling, thereby improving heating efficiency and consistency of product quality; the dual-path air intake design has a certain redundancy function. If there is a problem with the gas supply in one path, the other path can still maintain some functions, ensuring the stability and safety of the system.

[0014] Furthermore, the nitrogen pipeline includes nitrogen pipeline 1, the nitrogen pipeline 1 and the water vapor pipeline are connected to pipeline 6 through tee 2, the pipeline 6 is connected to pipeline 4 and pipeline 5 through tee 3, and the pipeline 4 and pipeline 5 are connected to pipeline 2 and pipeline 3 respectively.

[0015] The beneficial effect is that nitrogen carries water vapor into the preheater and then into the reactor 1. Nitrogen, as a gas with very stable chemical properties, is not easy to react with other substances. Therefore, during high-temperature reactions, it can effectively prevent impurities such as oxygen from entering, protect the reaction products from oxidation, and inhibit other unnecessary side reactions, thereby ensuring the purity of hydrogen.

[0016] Furthermore, the nitrogen pipeline includes a second nitrogen pipeline, and the second nitrogen pipeline is connected to the first pipeline.

[0017] Beneficial effect: Nitrogen pipeline 2 is connected to pipeline 1, which can purge pipeline 2 and pipeline 3 to prevent residual lignite tail gas in pipeline 2 and pipeline 3 and subsequent equipment and pipelines, thereby affecting the purity of hydrogen.

[0018] Furthermore, a check valve is provided on the first pipeline, and the check valve is located between the blower and the second nitrogen pipeline.

[0019] The beneficial effect is that the check valve can prevent nitrogen from flowing back to the fan when blowing the preheater and other equipment, ensure the one-way flow characteristics of the pipeline system, and prevent the fan from being subjected to reverse pressure shock. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the utility model.

[0021] Among them, 1. Purifier; 2. Fan; 3. Preheater; 4. Reactor; 5. Heat exchanger; 6. Gas-liquid separator; 7. Pipeline 1; 8. Pipeline 2; 9. Pipeline 3; 10. Nitrogen pipeline 2; 11. Gas detector; 12. Steam pipeline; 13. Nitrogen pipeline 1; 15. Pipeline 4; 14. Pipeline 6; 16. Pipeline 5; 17. Main pipeline. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Those skilled in the art should know that the embodiments described below are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model.

[0023] A blue carbon tail gas treatment system, such as Figure 1 As shown, it includes a purifier 1, a fan 2, a preheater 3, a reactor 4, a heat exchanger 5 and a gas-liquid separator 6.

[0024] Activated carbon is used as adsorption filler in the purifier 1. The purified blue charcoal tail gas is pressurized by the fan 2 to meet the pressure drop of the entire system process. The air outlet of the fan 2 is connected to the pipeline 17, and the pipeline 17 is respectively connected to the pipeline 28 and the pipeline 39 through the three-way one. The pipeline 28 and the pipeline 39 are used to connect the air inlet of the preheater 3. The nitrogen pipeline includes the nitrogen pipeline 13 and the nitrogen pipeline 2 10. The pipeline 17 is connected to the nitrogen pipeline 2 10. The pipeline 17 is provided with a check valve, and the check valve is located between the fan 2 and the nitrogen pipeline 2 10. The water vapor pipeline 12 and the nitrogen pipeline 13 are connected to the pipeline 6 14 through the three-way two, and the water vapor and nitrogen are mixed in the pipeline 6 14; the pipeline 6 14 is connected to the pipeline 4 15 and the pipeline 5 16 through the three-way three, and the pipeline 4 15 and the pipeline 5 16 are respectively connected to the pipeline 2 8 and the pipeline 3 9. The preheater 3 is used to quickly heat the gas sent from the pipeline 2 8 and the pipeline 3 9 to 850°C, and then send it to the reactor 4. The exhaust port of the reactor 4 is connected to the heat exchanger 5 and the gas-liquid separator 6 in sequence, wherein the heat exchanger 5 is a condenser and uses circulating desalted water for cooling. The gas-liquid separator 6 is connected to the gas detector 11, and the pipeline between the fan 2 and the preheater 3 is connected to the gas detector 11. Figure 1 The pipeline 2 8 between the three-way 1 and the valve is connected to the gas detector 11.

[0025] The operating steps of this system are:

[0026] 1) The blue coke tail gas enters the purifier 1 from the main pipeline 17 through the pressure reducing valve, and the purifier 1 removes impurities such as dust and tar in the blue coke tail gas that affect the activity of the oxygen carrier;

[0027] 2) The purified blue coke tail gas is pressurized by the fan 2 to meet the pressure drop of the entire system process. Pipeline 2 8 and pipeline 3 9 are successively installed with valves and flow meters along the gas flow direction to control the intake volume of blue coke tail gas. Blue coke tail gas is sent to the gas detector 11 to detect the content of dust, tar and other impurities in the blue coke tail gas. When the test is qualified, the valve sends the blue coke tail gas to the preheater 3. When the test is unqualified, the valve sends the blue coke tail gas back to the main pipeline 17;

[0028] 3) The pressurized blue carbon tail gas enters the preheater 3 and is heated to 850°C;

[0029] 4) The heated blue coke tail gas enters the reactor 4 for the first step of the reaction. The reactor 4 is a fluidized bed filled with perovskite as an oxygen carrier to carry iron oxide. The first step of the reaction is that the methane, carbon monoxide and hydrogen in the blue coke tail gas capture the oxygen element in the oxygen carrier. The specific reaction equation is:

[0030] CH4+4Fe2O3→8FeO+CO2+2H2O

[0031] CO+Fe2O3→CO2+2FeO

[0032] H2+Fe2O3→H2O+2FeO

[0033] 5) After the first step of the reaction is completed, the gas passes through the heat exchanger 5 and the gas-liquid separator 6 from the exhaust port of the reactor 4 to cool down, and the gas detector 11 detects the gas composition after cooling down, and the detection result corresponds to the reaction degree of the blue carbon tail gas; if the reaction is complete, it is discharged as waste gas, and if the reaction is incomplete, it flows back to the main pipeline 17;

[0034] 6) Nitrogen is introduced into pipeline 1 through nitrogen pipeline 2 10. Due to the effect of the check valve, nitrogen can only flow in the direction of the preheating tank; nitrogen purges the preheater 3, reactor 4, heat exchanger 5 and gas-liquid separator 6 for 5 minutes, and the blue carbon tail gas in the equipment and each pipeline is blown into the main pipeline 17;

[0035] 7) The water vapor and nitrogen are mixed in the pipeline 6 14 and enter the preheater 3 through the pipeline 2 8 and the pipeline 3 9. After the preheating is completed, the nitrogen brings the water vapor into the reactor 4. The water vapor reacts with the oxygen carrier after being deprived of oxygen to form high-purity hydrogen. The specific equation is:

[0036] H2O+2FeO→Fe2O3+H2

[0037] 8) The gas after the second step reaction is cooled from the exhaust port of the reactor 4 through the heat exchanger 5 and the gas-liquid separator 6 in sequence. The gas after the cooling is tested for hydrogen concentration by the gas detector 11. If the test is qualified, it is sent to the hydrogen pipeline. If the test is unqualified, it is sent to the main pipeline 17;

[0038] 9) Nitrogen is introduced into pipeline 1 7 through nitrogen pipeline 2 10, and the nitrogen is purged into the preheater 3, reactor 4, heat exchanger 5 and gas-liquid separator 6 for 5 minutes, and the water vapor, nitrogen and hydrogen in the equipment and each pipeline are blown into the main pipeline 17;

[0039] 10) Continue with step 1) to repeat the next cycle.

Claims

1. A blue carbon tail gas treatment system, characterized in that: The invention comprises a purifier (1), a fan (2), a preheater (3), a reactor (4), a heat exchanger (5) and a gas-liquid separator (6) which are arranged in sequence along the flow direction of the blue coke tail gas. The purifier (1) is used to remove impurities in the blue coke tail gas sent from the main pipeline (17). The fan (2) is used to pressurize the purified blue coke tail gas and send it into the preheater (3) for heating. The pipeline between the preheater (3) and the fan (2) is connected to a nitrogen pipeline and a water vapor pipeline (12). The reactor (4) is used to contain iron oxide so that after the semi-coke tail gas heated by the preheater (3) enters the reactor (4), it reacts with the iron oxide to generate ferrous oxide; the nitrogen pipeline is used to guide the nitrogen to sequentially purge the preheater (3), the reactor (4), the heat exchanger (5) and the gas-liquid separator (6) after the semi-coke tail gas and the iron oxide react; the water vapor pipeline (12) is used to guide the water vapor into the reactor (4) after the nitrogen purge and react with the ferrous oxide to generate hydrogen.

2. A blue carbon tail gas treatment system according to claim 1, characterized in that: The gas-liquid separator (6) is connected to a gas detector (11), and the gas detector (11) is used to detect the composition of the gas discharged from the gas-liquid separator (6).

3. A blue carbon tail gas treatment system according to claim 2, characterized in that: The pipeline between the fan (2) and the preheater (3) is connected to a gas detector (11), and the gas detector (11) is used to detect the composition of the blue carbon tail gas after being purified by the purifier (1).

4. A blue carbon tail gas treatment system according to claim 3, characterized in that: The air outlet of the fan (2) is connected to pipeline one (7), and pipeline one (7) is respectively connected to pipeline two (8) and pipeline three (9) through three-way one, and pipeline two (8) and pipeline three (9) are used to connect to the air inlet of the preheater (3).

5. A blue carbon tail gas treatment system according to claim 4, characterized in that: The nitrogen pipeline comprises a nitrogen pipeline one (13), wherein the nitrogen pipeline one (13) and the water vapor pipeline (12) are connected to a pipeline six (14) through a three-way two-way connection, and the pipeline six (14) is connected to a pipeline four (15) and a pipeline five (16) through a three-way three-way connection, and the pipeline four (15) and the pipeline five (16) are connected to the pipeline two (8) and the pipeline three (9) respectively.

6. A blue carbon tail gas treatment system according to claim 5, characterized in that: The nitrogen pipeline includes a second nitrogen pipeline (10), and the second nitrogen pipeline (10) is connected to the pipeline one (7).

7. A blue carbon tail gas treatment system according to claim 6, characterized in that: The pipeline one (7) is provided with a check valve, and the check valve is located between the fan (2) and the nitrogen pipeline two (10).

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