Energy-saving method capable of realizing crude coal gasification recovery and coal gas purification

Abstract

The invention provides an energy-saving method capable of realizing crude gas gasification recovery and gas purification, and belongs to the field of crude gas purification. The raw coke oven gas purification process sequentially comprises the working sections of condensation and air blowing, ammonia distillation, benzene elution, desulfurization and ammonium sulfate, and industrial clean gas is obtained after treatment. According to the process, two cooling links and one heating link are omitted, chemical recovery and purification of the raw gas are realized in the whole process, frequent heat exchange of the gas is reduced, and the process has the advantages of low energy consumption, complete process and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of coal chemical industry, and more particularly, to an energy-saving method for realizing the recovery of crude gasification products and gas purification of crude gas. Background Art

[0002] Crude gas is one of the products generated by the high-temperature dry distillation of coal under anaerobic conditions. The crude gas coming out of the coke oven contains impurities such as tar, crude benzene, naphthalene, ammonia, and hydrogen sulfide. Its composition is complex, and its utilization rate is low. Direct emission will pollute the environment and bring pressure to the environment. Direct combustion as fuel will also generate a large amount of toxic and harmful gases. In order to improve the utilization value of crude gas and reduce the environmental protection pressure, impurities that affect the gas combustion effect and pollute the environment must be removed before use.

[0003] In the traditional positive-pressure crude gas purification process, the blower is set in front of the chemical product recovery section, that is, the chemical product recovery process is in a positive-pressure state. After the crude gas is initially cooled, the temperature drops to about 22 °C, and after being compressed and heated by the blower, the temperature reaches about 58 °C. Then, a desulfurization pre-cooling tower is set to cool the gas temperature to about 40 °C. After desulfurization, the gas also needs to be provided with a ammonium sulfate pre-heater. After the gas comes out of the ammonium sulfate saturator, it needs to be finally cooled to meet the requirements of benzene washing. In this process, the energy flow is in a state of disorderly change, the temperature changes very frequently, and the temperature change gradient is large. Due to the unreasonable process flow, a large amount of energy is consumed in changing the gas temperature, which results in high energy consumption in the chemical product recovery process. Summary of the Invention

[0004] The main object of the present invention is to provide an energy-saving method for realizing the recovery of crude gasification products and gas purification of crude gas, so as to solve the problem of high energy consumption in the purification of crude gas in the prior art.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] (1) Remove the toxic and harmful substances from the crude gas output from the coal coke oven, and at the same time recover chemical products such as coal tar, sulfide, ammonia, and crude benzene;

[0007] (2) Cool the crude gas in the bridge pipe and the collecting pipe;

[0008] (3) Adjust the process, and carry out ammonia removal, benzene washing, and desulfurization treatment on the crude gas under a negative pressure environment;

[0009] (4) Further process the crude gas through an ammonium sulfate recovery tower and a benzene stripping tower.

[0010] Furthermore, by adjusting the process, the benzene washing and stripping process and the desulfurization process are interchanged, and the blower is moved behind the desulfurization tower.

[0011] Furthermore, the raw coke oven gas is cooled to 80 - 85 °C in the bridge pipe and the collecting pipe, and then further cooled to 25 - 40 °C in the primary cooler.

[0012] Furthermore, after condensation, the raw coke oven gas separates tar and ammonia water in the tar-ammonia water clarifier. After the ammonia water is sent to the ammonia distillation column for ammonia distillation treatment, it is then sent to the ammonium sulfate saturator to recover ammonia in the gas.

[0013] Furthermore, after condensation, the raw coke oven gas is directly sent to the benzol scrubber, where the gas comes into full contact with the scrubbing oil to absorb the benzene hydrocarbons in the gas.

[0014] Furthermore, after passing through the benzol scrubber, the raw coke oven gas is directly sent to the desulfurization tower, where hydrogen sulfide is removed using the alkali source in the gas.

[0015] Furthermore, after passing through the desulfurization tower, the raw coke oven gas is directly connected to a blower and then to an ammonium sulfate saturator.

[0016] Furthermore, the rich oil coming out of the benzol scrubber is subjected to debenzolization.

[0017] The present invention also provides an energy-saving method for realizing the recovery of raw coke oven gas and the purification of coke oven gas, and this process includes the following steps:

[0018] (1) The raw coke oven gas escaping from the riser pipe of the coke oven carbonization chamber is sprayed strongly through nozzles with circulating ammonia water having a gauge pressure of 0.15 - 0.20 Mpa in the bridge pipe and the collecting pipe. The ammonia water sprayed into fine mist comes into full contact with the gas. A large amount of ammonia water evaporates and absorbs heat, cooling the gas to 80 - 85 °C. Then, the gas is cooled in an indirect-direct combined cooler. The raw coke oven gas at about 82 °C from the collecting pipe first enters the indirect cooler and is cooled to about 50 °C, and then enters the direct cooling tower and is directly sprayed and cooled with ammonia water to 25 - 40 °C.

[0019] (2) After being cooled by the primary cooler, the gas still contains a small amount of tar mist that has not been completely removed. A tubular electrostatic tar precipitator is used to remove the tar mist. The outer shell of the tubular electrostatic tar precipitator is cylindrical, and the bottom is a conical bottom with a steam jacket. At the center of each precipitation tube, a corona wire is suspended. During operation, the gas is introduced from the bottom, and after purification, it is evenly distributed to each precipitation tube through two gas distribution sieve plates and escapes from the top. The tar collected by the precipitation tubes is discharged from the bottom outlet of the electrostatic tar precipitator.

[0020] (3) A centrifugal blower is used to transport the gas to the subsequent process sections.

[0021] (4) Since the relative densities of tar and ammonia water differ greatly and are easy to separate, a mechanical tar-ammonia water clarifier is used to separate tar and ammonia water.

[0022] (5) After the raw material ammonia water is heated to 90°C by the hot waste water in the heat exchanger, it enters the upper part of the ammonia distillation tower. Direct steam is used as the heat source at the bottom of the tower for steaming and blowing to distill out the ammonia in the ammonia water. The ammonia content in the waste water is not higher than 0.01%. The mixed gas at 101 - 103°C escaping from the top of the tower enters the ammonia condenser. Part of the ammonia is condensed and refluxed to the ammonia distillation tower, and the concentrated ammonia enters the saturator.

[0023] (6) The benzol hydrocarbons in the gas are absorbed by the wash oil. The gas flows from bottom to top, and the wash oil flows from top to bottom. The wash oil and the gas are in counter-current contact to absorb the benzol hydrocarbons in the wash oil. The wash oil absorption method can reduce the naphthalene content in the gas to less than 0.5 g / m 3

[0024] (7) The rich oil after benzene washing is indirectly heated by a tubular furnace to reach a temperature of 180 - 190°C and then enters the debenzolization tower to remove the crude benzene in the rich oil. The crude benzene vapor at 90 - 93°C distilled from the top of the debenzolization tower is cooled to about 73°C after heat exchange with the rich oil and enters the condensation cooler. The condensate enters the oil-water separator. After separating the water, the crude benzene flows into the reflux tank. Part of the crude benzene is sent to the top of the tower as reflux, and the rest is taken out as a product.

[0025] (8) The raw gas after passing through the benzene washing tower enters the desulfurization section. In the ammonia water method desulfurization, the sprayed circulating ammonia water is in counter-current contact with the raw gas in the desulfurization tower, and ammonia is used to absorb acidic gases such as hydrogen sulfide in the raw gas.

[0026] (9) The ammonia in the gas is recovered by absorbing it with the absorbent sulfuric acid.

[0027] Further, the raw gas treatment unit includes a condensation and blast system, a tar recovery system, a debenzolization treatment device, a desulfurization treatment device, an ammonia distillation treatment device, an ammonia washing treatment device, and a benzene washing treatment device. Through a series of subsequent gas purification treatments, the tar in the gas is recovered, and impurities such as naphthalene, sulfur, ammonia, and benzene remaining in the gas are removed. The finally obtained gas can be directly introduced into the gas holder or supplied to the public. In this process, high-quality sulfur can be obtained in the desulfurization treatment, high-quality ammonium sulfate can be obtained in the ammonia washing treatment, and high-quality crude benzene can be obtained after the debenzolization treatment.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) By adjusting the process, the consumption of circulating cooling water, low-temperature cooling water, and low-pressure steam in this process is significantly reduced, and two cooling processes and one heating process are reduced.

[0030] (2) After adjusting the process, due to the reduction of the cooling and heating processes, the equipment cost and floor area are reduced, and the production cost of the enterprise is lowered.

[0031] (3)Improved the energy efficiency and efficiency, and enhanced the energy utilization rate.

[0032] (4)The entire process achieved the recovery of by-products from raw coal gasification and the purification of coal gas, avoiding the high energy consumption caused by frequent temperature changes during the purification of raw coal gas. The entire process realized the recovery and purification of by-products from raw coal gas, reduced the frequent heat exchange of coal gas, and had the advantages of low energy consumption, complete process, and low cost.

[0033] The following further describes the present invention in conjunction with the accompanying drawings and specific embodiments. The additional aspects and advantages of the present invention will be given in the following description section, some of which will become apparent from the following description, or will be understood through the practice of the present invention. Description of the Drawings

[0034] The drawings forming a part of the present invention are used to assist in understanding the present invention. The content provided in the drawings and the related descriptions in the present invention can be used to explain the present invention, but do not constitute an improper limitation to the present invention. In the drawings:

[0035] Figure 1 is a schematic diagram of the energy-saving process for the recovery of by-products from raw coal gasification and the purification of coal gas of the present invention. Detailed Description of the Embodiments

[0036] The following clearly and completely describes the present invention in conjunction with the accompanying drawings. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. Before describing the present invention in conjunction with the accompanying drawings, it should be particularly noted that:

[0037] The technical solutions and technical features provided in each part including the following description in the present invention can be combined with each other without conflict.

[0038] In addition, the embodiments of the present invention described below are generally only a part of the embodiments of the present invention, rather than all of the embodiments. Therefore, all other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0039] Regarding the terms and units in the present invention. The terms "including", "having" and any variations thereof in the specification, claims and related parts of the present invention are intended to cover non-exclusive inclusion.

[0040] An energy-saving method for realizing the recovery of by-products from raw coal gasification and the purification of coal gas according to the present invention includes the following steps:

[0041] (1) Remove the toxic and harmful substances from the raw coke oven gas output from the coal coking furnace, and simultaneously recover chemical products such as coal tar, sulfides, ammonia, and crude benzene;

[0042] (2) Cool the raw coke oven gas in the bridge pipe and the collecting pipe;

[0043] (3) Adjust the process, and carry out ammonia removal, benzene washing, and desulfurization treatment on the raw coke oven gas under a negative pressure environment;

[0044] (4) Further process the raw coke oven gas through the ammonium sulfate recovery tower and the benzene stripping tower.

[0045] In step (1), swap the benzene washing and desulfurization processes by adjusting the process, and move the blower behind the desulfurization tower.

[0046] Further, the raw coke oven gas cools the gas to 80 - 85 °C in the bridge pipe and the collecting pipe, and then further cools the gas to 25 - 40 °C in the primary cooler.

[0047] Further, after the raw coke oven gas is condensed, separate the tar and ammonia water in the tar and ammonia water clarifier, send the ammonia water to the ammonia distillation tower for ammonia distillation treatment, and then send it to the ammonium sulfate saturator to recover the ammonia in the gas.

[0048] Further, after the raw coke oven gas is condensed, directly send it to the benzene washing tower, and in the benzene washing tower, the gas fully contacts the washing oil to absorb the benzene hydrocarbons in the gas.

[0049] Further, after the raw coke oven gas passes through the benzene washing tower, directly send it to the desulfurization tower, and in the desulfurization tower, use the alkali source in the gas to remove hydrogen sulfide.

[0050] Further, after the raw coke oven gas passes through the desulfurization tower, directly connect the blower, and then connect the ammonium sulfate saturator.

[0051] Further, carry out benzene stripping on the rich oil coming out of the benzene washing tower.

[0052] As Figure 1 shown, the energy-saving method for the recovery of raw coke oven gasification products and gas purification in the present invention includes a condensation and blowing section, an ammonia distillation section, a benzene washing and stripping section, and a desulfurization section connected in sequence.

[0053] Figure 1 The arrow direction in

[0054] is the gas purification flow direction.

[0055] 1. The raw gas escaping from the rising pipe of the coke oven carbonization chamber is sprayed strongly in the bridge pipe and the collecting pipe with circulating ammonia water at a gauge pressure of 0.15 - 0.20 Mpa through nozzles. The ammonia water sprayed into fine mist comes into full contact with the gas. A large amount of ammonia water evaporates and absorbs heat, cooling the gas to 80 - 85 °C. Then, the gas is cooled in an indirect-direct combined cooler. The raw gas at about 82 °C from the collecting pipe first enters the indirect cooler and is cooled to about 50 °C, and then enters the direct cooling tower, where it is directly sprayed and cooled with ammonia water to 25 - 40 °C.

[0056] 2. After being cooled by the primary cooler, the gas still contains a small amount of tar mist that has not been completely removed. A tubular electrostatic tar precipitator is used to remove the tar mist. The shell of the tubular electrostatic tar precipitator is cylindrical, and the bottom is a conical bottom with a steam jacket. At the center of each precipitation tube, a corona wire is suspended. During operation, the gas is introduced from the bottom, and after purification, it is evenly distributed to each precipitation tube through two gas distribution sieve plates and escapes from the top. The tar collected by the precipitation tubes is discharged from the bottom outlet of the electrostatic tar precipitator. A centrifugal blower is used to transport the gas to the subsequent process section.

[0057] 3. Since the relative densities of tar and ammonia water differ greatly and are easy to separate, a mechanized tar-ammonia water clarifying tank is used to separate tar and ammonia water. The raw ammonia water is heated to 90 °C by hot wastewater in a heat exchanger and then enters the upper part of the ammonia distillation tower. Direct steam is used as the heat source at the bottom of the tower for steaming and blowing to distill out the ammonia in the ammonia water. The ammonia content in the wastewater is not higher than 0.01%. The mixed gas at 101 - 103 °C escaping from the top of the tower enters the ammonia partial condenser, where part of the ammonia is condensed and refluxed to the ammonia distillation tower, and the concentrated ammonia enters the saturator.

[0058] 4. The wash oil absorption method is used to absorb the benzene hydrocarbons in the gas. The gas flows from bottom to top, and the wash oil flows from top to bottom. The wash oil and the gas are in countercurrent contact to absorb the benzene hydrocarbons in the wash oil. The wash oil absorption method can reduce the naphthalene content in the gas to less than 0.5 g / m 3 。

[0059] 5. The rich oil after benzene washing is indirectly heated by a tubular furnace to reach 180 - 190 °C and then enters the debenzolization tower to remove the crude benzene in the rich oil. The crude benzene vapor at 90 - 93 °C evaporated from the top of the debenzolization tower is cooled to about 73 °C after heat exchange with the rich oil and enters the condensation cooler. The condensate enters the oil-water separator. After separating the water, the crude benzene flows into the reflux tank. Part of the crude benzene is sent to the top of the tower as reflux, and the rest is taken out as a product. The raw gas after passing through the benzene washing tower enters the desulfurization section. In the ammonia water method desulfurization, the sprayed circulating ammonia water is in countercurrent contact with the raw gas in the desulfurization tower to absorb acidic gases such as hydrogen sulfide in the raw gas with ammonia. To recover the ammonia in the gas, the absorbent sulfuric acid is used to absorb the ammonia in the gas.

[0060] Sixthly, the raw coke oven gas treatment unit includes a condensation and blast system, a tar recovery system, a debenzolization treatment device, a desulfurization treatment device, an ammonia distillation treatment device, an ammonia washing treatment device, and a benzol washing treatment device. Through a series of subsequent gas purification treatments, the tar in the gas is recovered, and impurities such as residual sulfur, ammonia, and benzene in the gas are removed. The finally obtained gas can be directly introduced into a gas holder or supplied for civilian use. In this process, high-quality sulfur can be obtained through desulfurization treatment, high-quality ammonium sulfate can be obtained through ammonia washing treatment, and high-quality crude benzene can be obtained after debenzolization treatment.

[0061] Taking the chemical product recovery and gas purification of the raw coke oven gas produced by a certain coking plant as an example to explain the present invention, the products and yields of high-temperature dry distillation of coal under industrial production conditions are shown in Table 1:

[0062] Table 1 Products and yields of high-temperature dry distillation of coal under industrial production conditions

[0063] Product Coke Coke oven gas Tar Crude benzene Ammonia Sulfur Water ASH Yield 75 15 3 0.8 0.25 0.16 2 3.79

[0064] Table 2 Composition and content of raw coke oven gas

[0065] Component <![CDATA[H 2 > <![CDATA[CH 4 > CO <![CDATA[N 2 > <![CDATA[CO 2 > <![CDATA[C 2 H 6 > <![CDATA[O 2 > Content 58 26 6.2 4.5 2.2 2.5 0.6

[0066] The composition of tar is extremely complex, and the composition of tar is shown in Table 3:

[0067] Table 3 Composition and content of tar

[0068] Component <![CDATA[C 10 H 8 > <![CDATA[C 6 H 6 O]]> <![CDATA[C 14 H 10 > <![CDATA[C 16 H 10 > Content 16.15 34.04 44.68 5.13

[0069] Table 4 Composition and content of crude benzene

[0070] Component <![CDATA[C 6 H 6 > <![CDATA[C 7 H 8 > <![CDATA[C 8 H 10 > Content 82.48 13.05 4.47

[0071] Table 5 Comparison of circulating water volume and energy consumption

[0072]

[0073] Compared with the traditional production method, the present invention cancels the process of repeatedly heating and cooling the gas, correspondingly shortens the process, reduces the use of equipment, reduces the capital investment, reduces the floor area, makes the temperature change curve of the gas more reasonable, and reduces the use of circulating water and cooling water, reduces the energy consumption, and the energy efficiency is significantly higher than that of the traditional process, improving the utilization rate of energy. Therefore, the present invention is more energy-saving, reduces the cost of the enterprise, and brings economic benefits to the enterprise. The efficiency is significantly higher than that of the traditional process, improving the utilization rate of energy. Therefore, the present invention is more energy-saving, reduces the cost of the enterprise, and brings economic benefits to the enterprise.

[0074] The gas purified by the above raw coke oven gas purification method meets the national standards.

[0075] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An energy-saving method for realizing waste coal gasification product recovery and coal gas purification, characterized in that: (1) Remove toxic and harmful substances from the raw gas output from the coal coke oven, and recover chemical products such as coal tar, sulfide, ammonia, and crude benzene; (2) Cooling the raw gas in the bridge pipe and gas collecting pipe; (3) Adjust the process to remove ammonia, wash benzene and desulfurize the raw gas under negative pressure; (4) The raw gas is further treated through an ammonium sulfate recovery tower and a benzene removal tower.

2. The energy-saving method for realizing waste coal gasification product recovery and coal gas purification as claimed in claim 1, characterized in that: In step (1), the benzene stripping step and the desulfurization step are interchanged through an adjustment process, and the blower is moved after the desulfurization tower.

3. The energy-saving method for realizing waste coal gasification product recovery and coal gas purification as claimed in claim 1, characterized in that: In step (2), the raw coal gas is cooled to 80-85°C in the bridge pipe and the gas collecting pipe, and then further cooled to 25-40°C in the primary cooler.

4. The energy-saving method for realizing waste coal gasification product recovery and gas purification as claimed in claim 1, characterized in that: In step (3), the raw coal gas is condensed and then the tar and ammonia water are separated in a tar ammonia water clarifier. The ammonia water is sent to an ammonia evaporator for ammonia evaporation and then sent to an ammonium sulfate saturator to recover ammonia in the coal gas.

5. The energy-saving method for realizing waste coal gasification product recovery and gas purification as claimed in claim 1, characterized in that: In step (3), the raw coal gas is directly sent to the benzene washing tower after condensation, and in the benzene washing tower, the coal gas is fully contacted with the washing oil to absorb the benzene hydrocarbons in the coal gas.

6. The energy-saving method for realizing waste coal gasification product recovery and coal gas purification as claimed in claim 1, characterized in that: In step (3), the raw coal gas is directly sent to the desulfurization tower after passing through the benzene washing tower, and the hydrogen sulfide is removed in the desulfurization tower by utilizing the alkali source in the coal gas.

7. The energy-saving method for realizing waste coal gasification product recovery and coal gas purification as claimed in claim 1, characterized in that: In step (4), after the raw coal gas passes through the desulfurization tower, it is directly connected to the blower and then to the ammonium sulfate saturator.

8. The energy-saving method for realizing waste coal gasification product recovery and coal gas purification as claimed in claim 1, characterized in that: In step (4), the rich oil from the benzene washing tower is debenzened.

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