Method for producing synthesis gas from semi-coke oven gas

Abstract

The application discloses a method for preparing synthetic gas from semi-coke coke oven gas, and belongs to the technical field of coal pyrolysis dry distillation. The method dries and preheats raw coal, adopts external heating type dry distillation, and obtains raw coal gas and semi-coke semi-product. The raw coal gas is cooled and electrically captures tar to obtain semi-coke coke oven gas. The semi-coke coke oven gas can be used for cooling the semi-coke semi-product, and the semi-coke powder in the semi-coke semi-product is separated to obtain powder coal gas. The powder coal gas enters a gasification furnace and reacts with water vapor to obtain gasification coal gas. The heat of the gasification coal gas is recycled in sequence through dry distillation and drying preheating, and then dust removal is performed to obtain synthetic gas. The effective component content of the synthetic gas is higher than 95%, and the synthetic gas can be used for producing basic raw materials such as synthetic ammonia, methanol and low-carbon olefin, and can also be used as clean energy. The method does not generate waste gas and smoke, can fully utilize coal resources, and obtains high-quality semi-coke product, coal tar and synthetic gas.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal pyrolysis dry distillation, in particular to a method for preparing synthetic gas from coke oven gas of semi-coke. BACKGROUND

[0002] Semi-coke (also known as semi-coke, coke powder) is blocky, generally less than 80mm in particle size, and light black in color, and is widely used in chemical industry, smelting, gas making and other industries. It is better than coke in the production of high energy-consuming products such as metallic silicon, ferrosilicon, silicon iron, silicon manganese, chemical fertilizer, calcium carbide, etc.

[0003] At present, semi-coke is mainly produced by using an internal heating type dry distillation furnace, but this process has the following shortcomings: (1) the raw coal is generally block coal with a particle size of 20-80mm, and the powder coal resources cannot be reasonably and effectively utilized. The existing technology can gasify the powder coal, and then utilize the heat energy after gasification, but it will produce waste flue gas, which is difficult to handle subsequently; (2) the semi-coke product is quenched by water vapor, which causes part of the semi-coke to be gasified, reduces the yield of semi-coke, and increases the number of pores in the semi-coke, thereby reducing the mechanical strength of the semi-coke and resulting in poor quality of the semi-coke product; (3) this process uses air as a combustion-supporting agent, which brings in a large amount of inert gas, resulting in low calorific value of the out-of-furnace coal gas and affecting its subsequent processing and utilization. SUMMARY

[0004] In view of the shortcomings of the prior art, the present application provides a method for preparing synthetic gas from coke oven gas of semi-coke, which dries and preheats the raw coal, uses external heating type dry distillation to obtain raw coal gas and semi-coke semi-product, cools and electrically captures tar from the raw coal gas to obtain coke oven gas of semi-coke; the coke oven gas of semi-coke can be used to cool the semi-coke semi-product, and the semi-coke powder in the semi-coke semi-product is separated to obtain powder coal gas, which is introduced into a gasification furnace to react with water vapor to obtain gasification coal gas; the heat of the gasification coal gas is recycled in sequence for dry distillation and drying preheating, and then dust removal is performed to obtain synthetic gas, which has a content of effective components of more than 95%, and can be used to produce basic raw materials such as synthetic ammonia, methanol, low-carbon olefins, etc., or can be used as clean energy. The method of the present application does not produce waste flue gas, can fully utilize coal resources, and obtain high-quality semi-coke products, coal tar and synthetic gas.

[0005] The technical scheme adopted by the present application is as follows:

[0006] A method for preparing synthetic gas from coke oven gas of semi-coke, comprising the following steps:

[0007] Step S1. Indirectly contacting the raw coal with a drying medium to dry and preheat the raw coal, and the gas and non-chemically combined water stored in the raw coal are released;

[0008] Step S2. External heating type dry distillation of the preheated raw coal to obtain semi-coke semi-product and raw coal gas;

[0009] Step S3. The semi-finished semi-coke is brought into countercurrent contact with the cooling medium to quench the coke. At the same time, under the pneumatic carrying effect of the cooling medium, the semi-coke powder is separated from the semi-coke lumps along with the cooling medium to obtain the finished semi-coke.

[0010] Step S4. Collect and buffer the raw coal gas, and then cool and treat it with electrostatic tar to obtain coal tar and semi-coke oven gas;

[0011] Step S5. Use the semi-coke oven gas as the cooling medium in step S3, and make countercurrent contact with the semi-coke semi-finished product to carry the semi-coke powder and separate it from the semi-coke lumps to obtain powder gas;

[0012] Step S6. The powdered coal gas is fed into the gasifier and mixed with water vapor at 1100~1200℃. The semi-coke powder and carbon dioxide in the powdered coal gas come into contact with the water vapor and undergo a complete gasification reaction to generate gasified coal gas. This gasified coal gas is first used as the heat source for external heating dry distillation in step S2, then used as the drying medium in step S1 to exchange heat with the raw coal, and finally purified by dust removal to obtain syngas.

[0013] In the method for producing syngas from semi-coke oven gas disclosed in this application, in step S6, after the gasified coal gas exchanges heat with the raw coal, it exchanges heat with water to prepare steam, which can be sent into the gasifier as a gasifying agent.

[0014] In the method for producing syngas from semi-coke oven gas disclosed in this application, in step S4, after the raw coal gas is treated by electrostatic tar removal, it is then subjected to desulfurization treatment to remove sulfides.

[0015] In the method for producing syngas from semi-coke oven gas disclosed in this application, the raw coal gas undergoes desulfurization treatment followed by dehydration treatment to remove moisture, thereby obtaining semi-coke oven gas.

[0016] In the method for producing syngas from semi-coke oven gas disclosed in this application, in step S1, the particle size of the raw coal is less than 50 mm.

[0017] In the method for producing syngas from semi-coke oven gas disclosed in this application, in step S3, the particle size of the semi-coke powder is less than 10 mm.

[0018] In the method for producing syngas from semi-coke oven gas disclosed in this application, the drying and preheating temperature of the raw coal in step S1 is 250~300℃.

[0019] In the method for producing syngas from semi-coke oven gas disclosed in this application, the temperature of the externally heated dry distillation in step S2 is 600~800℃.

[0020] In the method for producing syngas from semi-coke oven gas disclosed in this application, in step S6, the temperature of the gasified gas can be adjusted by the syngas or semi-coke oven gas to meet the temperature requirements for dry distillation and preheating drying.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] (1) In this application, the coke oven gas and semi-finished ...

[0023] (2) In this application, the powdered coal gas is fed into the gasifier for gasification reaction, which can make full use of the heat of the semi-finished semi-coke and avoid energy waste. The gas yield of low-temperature dry distillation is low. Using semi-coke powder and semi-coke coke oven gas to produce syngas improves the gas yield of low-temperature dry distillation of coal pyrolysis. The carbon dioxide in the semi-coke coke oven gas is used as the gasification raw material for semi-coke powder. While reducing the carbon dioxide content, it increases the effective component content of syngas. The quality of syngas is high and the semi-coke powder is also fully utilized. The particle size requirement of the raw coal entering the furnace is small. It is not necessary to screen out the powder or small particles in the raw coal, which reduces the workload. The heat of syngas is recovered and utilized through dry distillation and drying preheating in sequence. The energy utilization rate is high, and the purpose of energy saving and emission reduction is achieved.

[0024] (3) This application can obtain high-quality products such as semi-coke, coal tar, and syngas. The effective component content of the syngas is greater than 95%, which can be used to produce basic raw materials such as synthetic ammonia, methanol, and low-carbon olefins, and can also be used as clean energy. The method of this application does not generate waste flue gas, has a small waste output, high energy utilization rate, low production cost, and high product quality. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the process for producing syngas from semi-coke oven gas. Detailed Implementation

[0027] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0028] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0031] Please see Figure 1 As shown in the embodiment of this application, a method for producing syngas from semi-coke oven gas is provided, including the following steps:

[0032] Step S1. The raw coal is indirectly contacted with a drying medium for drying and preheating, causing the gas and non-chemically bound water stored in the raw coal to precipitate out. During the drying and preheating process, the appearance of the raw coal remains basically unchanged. The main purpose is to release the stored gas and non-chemically bound water from the coal, preventing the coal from undergoing a gasification reaction with the raw coal gas and water vapor at high temperatures during the subsequent dry distillation process. This would consume some of the semi-coke, reduce the yield of semi-coke, and increase the number of pores on the surface of the semi-coke, thereby reducing its strength.

[0033] Step S2. The preheated raw coal is subjected to external heating dry distillation to obtain semi-finished semi-coke and raw coal gas. The raw coal gas produced by external heating dry distillation mainly consists of coal tar, hydrogen, carbon monoxide, methane, and carbon dioxide, with hydrogen having the highest content, accounting for more than 40%. Compared with internal heating dry distillation, there is no large amount of inert gas mixed in, resulting in a pure composition and high calorific value. After purification, it can be used to obtain clean fuel.

[0034] Step S3. The semi-finished semi-coke is brought into countercurrent contact with a cooling medium for quenching. Simultaneously, under the pneumatic carrying effect of the cooling medium, the semi-coke powder separates from the semi-coke lumps, yielding the finished semi-coke. Current methods for grading finished semi-coke involve screening after production, which involves numerous steps. Furthermore, during loading, unloading, and transportation, semi-coke with low mechanical strength may break into powder, reducing the yield. This application introduces a countercurrent contact between the semi-finished semi-coke and a cooling medium. While being cooled, the semi-coke powder is carried out, resulting in a blocky finished semi-coke. This process is simple and convenient, directly producing high-quality semi-coke with a narrow particle size distribution, high yield, and excellent product quality.

[0035] Step S4. The raw coal gas is collected and buffered, then cooled and subjected to electrostatic precipitator treatment to obtain coal tar and semi-coke oven gas. The raw coal gas produced by dry distillation is collected and buffered, then cooled with cooling water to remove most of the coal tar. Electrostatic precipitator treatment further removes coal tar and water from the gas, yielding semi-coke oven gas. During the purification process, the temperature of the raw coal gas gradually decreases, which can be used to cool the semi-coke product.

[0036] Step S5. The coke oven gas from the semi-coke oven is used as the cooling medium in step S3, and it is brought into countercurrent contact with the semi-coke semi-finished product, carrying the semi-coke powder and separating it from the semi-coke lumps to obtain powdered gas. The temperature of the semi-coke semi-finished product after dry distillation is very high. The existing coke quenching method uses water or steam for cooling, which generates wastewater. At the same time, the heat of the semi-coke semi-finished product is wasted. Furthermore, because the steam reacts with the semi-coke at high temperature, it consumes fixed carbon, resulting in a decrease in yield, an increase in ash content, an increase in the number of pores on the surface of the semi-coke, a larger pore diameter, and a thinner pore wall, which reduces the mechanical strength of the semi-coke. This application utilizes coke oven gas to cool semi-finished ...

[0037] Step S6. The pulverized coal gas is fed into the gasifier and mixed with steam at 1100~1200℃. The semi-coke powder and carbon dioxide in the pulverized coal gas come into contact with the steam and undergo a complete gasification reaction to generate gasified coal gas. This gasified coal gas is first used as the heat source for external heating dry distillation in step S2, then as the drying medium in step S1 for heat exchange with the raw coal, and finally purified by dust removal to obtain syngas. After the pulverized coal gas enters the gasifier, a series of gasification reactions occur. For example, under high temperature conditions, the semi-coke powder comes into contact with steam to generate hydrogen and carbon monoxide. The carbon dioxide in the pulverized coal gas reacts with the semi-coke powder at high temperature to generate carbon monoxide. The temperature of the gasifier is controlled at 1100~1200℃. At this temperature, the carbon monoxide and hydrogen generated by the reaction of the semi-coke powder with carbon dioxide and steam have high contents, while ensuring complete gasification of the semi-coke powder to obtain high-temperature gasified coal gas. The heat from the gasification gas is successively recovered and utilized through dry distillation, drying and preheating, and then dust removal to obtain syngas. This syngas has a high content of effective components (hydrogen, carbon monoxide, and methane), and can be used to produce basic raw materials such as synthetic ammonia, methanol, and low-carbon olefins. It can also be used as a clean energy source for combustion power generation. Since the gas yield from low-temperature dry distillation is relatively low, this application uses semi-coke powder in the semi-coke production process to produce syngas, thereby increasing the gas yield from low-temperature dry distillation of coal pyrolysis. Carbon dioxide in the semi-coke coke oven gas is used as the gasification feedstock for the semi-coke powder, reducing the carbon dioxide content while increasing the content of effective components in the syngas. This results in high-quality syngas, full utilization of the semi-coke powder, and a smaller particle size requirement for the feed coal. It eliminates the need to screen out powder or small particles from the feed coal, reducing workload and fully utilizing the heat of the syngas to achieve energy conservation and emission reduction.

[0038] This application involves cooling and screening purified semi-coke coke oven gas to separate semi-coke powder from semi-coke lumps. The resulting powder gas carries heat into a gasifier, avoiding energy waste. The powder gas undergoes complete gasification in the gasifier to produce gasified gas. The heat from the gasified gas is then utilized through subsequent dry distillation and preheating, resulting in high energy efficiency. The obtained syngas has an effective component content greater than 95%, which can be used to produce basic raw materials such as synthetic ammonia, methanol, and low-carbon olefins, or as a clean energy source for combustion power generation. This method produces no waste gas, has low waste output, high energy efficiency, low production costs, and high-quality products.

[0039] In one embodiment, in step S6, after the gasified coal gas exchanges heat with the raw coal, it then exchanges heat with water to produce steam, which can be sent to the gasifier as a gasifying agent. The temperature of the gasified coal gas decreases after heat exchange with the raw coal, but it is still above 100°C, so it can exchange heat with water to produce steam.

[0040] In one embodiment, in step S4, after the raw coal gas is treated by electrostatic precipitator for tar, it is then subjected to desulfurization to remove sulfides. Specifically, after cooling and electrostatic precipitator treatment, the raw coal gas enters the desulfurization tower and comes into contact with the desulfurization liquid. Sulfides, tar, naphthalene, benzene, phenol, and other substances in the coal gas are removed, further purifying the coal gas and resulting in clean and high-quality syngas.

[0041] Specifically, the desulfurized coal gas is then dehydrated by a demister to reduce the water content in the coal gas and prevent it from undergoing a gasification reaction with semi-coke during the subsequent coke quenching process.

[0042] In one embodiment, the particle size of the raw coal is less than 50 mm. The raw coal becomes smaller during the dry distillation process due to component loss. This application controls the particle size of the raw coal to below 50 mm, and after dry distillation and sieving, medium-sized lump semi-coke can be obtained.

[0043] Specifically, by controlling the gas in the semi-coke oven, the gas pressure can be used to carry away semi-coke powder smaller than 10mm.

[0044] In one embodiment, the temperature of the drying medium is 250~300°C, at which the raw coal can be dried rapidly, and at the same time, the gas and non-chemically bound water stored in the raw coal are released.

[0045] In one embodiment, the temperature of the externally heated dry distillation is 600~800℃. The gasified coal gas discharged from the gasifier has a high temperature and a large amount of heat, which can be used as a heat source for externally heated dry distillation. It is then used as a drying medium to exchange heat with the raw coal, and then with water, making the most of its heat to achieve the purpose of energy conservation and emission reduction.

[0046] Specifically, since the effective components (hydrogen, carbon monoxide, methane, and carbon dioxide) of the purified semi-coke coke oven gas are greater than 90%, the temperature of the gasified gas can be adjusted using either semi-coke coke oven gas or syngas to meet the requirements of dry distillation and preheating drying. For example, at the gasifier exhaust port, if the gasified gas temperature is too high, the temperature can be adjusted using syngas to maintain it at 600-800℃.

[0047] In a specific implementation scenario, raw coal with a particle size of less than 50mm is indirectly contacted with gasified coal gas at 250-300℃ for drying and preheating, causing the gas and non-chemically bound water stored in the raw coal to precipitate out. The preheated raw coal is then subjected to external heating dry distillation at 650-750℃ to obtain semi-finished semi-coke and raw coal gas. The raw coal gas is collected and buffered, cooled with cooling water to remove most of the coal tar, and then further purified by electrostatic precipitator to remove coal tar and water. It then enters a desulfurization tower, where it comes into contact with desulfurization liquid to remove sulfides, tar, naphthalene, benzene, phenols, and other substances, further purifying the gas. After purification, it passes through a demister to remove water, yielding semi-coke coke oven gas. Coke oven gas and semi-finished semi-coke are contacted countercurrently for quenching. Simultaneously, under the pneumatic carrying effect of the coke oven gas, semi-coke powder smaller than 10mm is separated from semi-coke lumps along with the coke oven gas, yielding finished semi-coke and powder gas. The powder gas is then fed into a gasifier and mixed with steam at 1100~1200℃. The semi-coke powder, carbon dioxide, and steam in the powder gas come into contact with the steam, undergoing a complete gasification reaction to generate gasified gas. The temperature of this gasified gas is controlled at 650~750℃. It first enters a dry distillation furnace as a heat source, then as a drying medium for heat exchange with the raw coal, followed by heat exchange with water to produce steam, and finally dust removal and purification to obtain syngas.

[0048] The composition of the syngas was analyzed using a gas analyzer. The syngas mainly consisted of hydrogen, carbon monoxide, and methane, accounting for more than 95%, of which hydrogen accounted for 55.1%, carbon monoxide 28.7%, methane 12.8%, and carbon dioxide 1.3%.

[0049] The semi-coke product was tested and analyzed. The particle size of the semi-coke was 15~35mm, the fixed carbon content was 88.6%, the volatile matter was 4.2%, the moisture was 2.1%, the ash content was 4.7%, the sulfur content was 0.05%, and the phosphorus content was 0.05%.

[0050] This application involves countercurrent contact between semi-finished semi-coke coke oven gas and semi-finished semi-coke. During cooling, semi-coke powder is carried out, resulting in powdered gas and lumpy semi-coke. The coke oven gas is purified to remove moisture and is used to cool the semi-finished semi-coke without consuming the semi-coke or creating porosity. Screening occurs simultaneously with cooling. This process is simple and convenient, directly producing high-quality semi-coke with a narrow particle size distribution, high yield, and excellent product quality. The powdered gas is then fed into a gasifier for gasification, fully utilizing the heat from the semi-finished semi-coke and avoiding energy waste. Since low-temperature dry distillation yields relatively low gas production, the semi-finished semi-coke powder and coke oven gas are used to produce syngas. This method improves the gas yield of low-temperature carbonization in coal pyrolysis. Carbon dioxide from the coke oven gas is used as a gasification feedstock for semi-coke powder, reducing carbon dioxide content while increasing the effective component content of the syngas. This results in high-quality syngas and full utilization of the semi-coke powder. The required particle size of the feed coal is small, eliminating the need for screening to remove powder or small particles, thus reducing workload. The heat of the syngas is recovered and utilized through carbonization, drying, and preheating, resulting in high energy efficiency and achieving energy conservation and emission reduction. The obtained syngas has an effective component content greater than 95%, making it suitable for producing basic feedstocks such as synthetic ammonia, methanol, and low-carbon olefins, and also serving as a clean energy source. This method produces no waste gas, generates little waste, has high energy efficiency, low production costs, and yields high-quality products.

[0051] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing syngas from semi-coke oven gas, characterized in that, Includes the following steps: Step S1. Indirectly contact the raw coal with the drying medium to dry and preheat it, causing the gas and non-chemically bound water stored in the raw coal to precipitate out; Step S2. The preheated raw coal is subjected to external heating dry distillation to obtain semi-finished semi-coke and raw coal gas; Step S3. The semi-finished semi-coke is brought into countercurrent contact with the cooling medium to quench the coke. At the same time, under the pneumatic carrying effect of the cooling medium, the semi-coke powder is separated from the semi-coke lumps along with the cooling medium to obtain the finished semi-coke. Step S4. Collect and buffer the raw coal gas, and then cool and treat it with electrostatic tar to obtain coal tar and semi-coke oven gas; Step S5. Use the semi-coke oven gas as the cooling medium in step S3, and make countercurrent contact with the semi-coke semi-finished product to carry the semi-coke powder and separate it from the semi-coke lumps to obtain powder gas; Step S6. The powdered coal gas is fed into the gasifier and mixed with water vapor at 1100~1200℃. The semi-coke powder and carbon dioxide in the powdered coal gas come into contact with the water vapor and undergo a complete gasification reaction to generate gasified coal gas. This gasified coal gas is first used as the heat source for external heating dry distillation in step S2, then used as the drying medium in step S1 to exchange heat with the raw coal, and finally purified by dust removal to obtain syngas.

2. The method for producing syngas from semi-coke oven gas according to claim 1, characterized in that, In step S6, after the gasified coal gas exchanges heat with the raw coal, it exchanges heat with water to prepare steam, which can be sent into the gasifier as a gasifying agent.

3. The method for producing syngas from semi-coke oven gas according to claim 1, characterized in that, In step S4, after the raw coal gas is treated by electrostatic precipitator for tar, it is then subjected to desulfurization treatment to remove sulfides.

4. The method for producing syngas from semi-coke oven gas according to claim 3, characterized in that, The raw coal gas undergoes desulfurization treatment followed by dehydration treatment to remove moisture, yielding semi-coke coke oven gas.

5. The method for producing syngas from semi-coke oven gas according to claim 1, characterized in that, In step S1, the particle size of the raw coal is less than 50 mm.

6. The method for producing syngas from semi-coke oven gas according to claim 5, characterized in that, In step S3, the particle size of the semi-coke powder is less than 10 mm.

7. The method for producing syngas from semi-coke oven gas according to claim 1, characterized in that, In step S1, the drying and preheating temperature of the raw coal is 250~300℃.

8. The method for producing syngas from semi-coke oven gas according to claim 1, characterized in that, In step S2, the temperature of the externally heated dry distillation is 600~800℃.

9. The method for producing syngas from semi-coke oven gas according to claim 1, characterized in that, In step S6, the temperature of the gasified gas can be adjusted by syngas or semi-coke oven gas to meet the temperature requirements for dry distillation and preheating drying.

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