Pretreatment system and method for deep purification of coke oven gas

Abstract

The present invention provides a pretreatment system and method for deep purification of coke oven gas, which belongs to the field of coke oven gas purification, in order to solve the problem that impurities in coke oven gas before comprehensive utilization may cause compressor blockage and premature failure of desulfurizer for fine desulfurization, thereby increasing operating costs. It includes a pre-wash tower, a four-phase separator, a circulating pump and a heat exchanger, wherein the pre-wash tower is a supergravity rotating device, and the four-phase separator is a horizontal three-weir type gas-liquid-liquid-liquid separator, wherein: the gas phase inlet of the pre-wash tower is connected to the coke oven gas pipeline, the liquid phase outlet of the pre-wash tower is connected to the feed port of the four-phase separator, the intermediate phase fluid outlet of the four-phase separator is connected to the liquid inlet of the circulating pump, the liquid outlet of the circulating pump is connected to the liquid inlet of the heat exchanger, and the liquid outlet of the heat exchanger is connected to the liquid phase inlet of the pre-wash tower.

Description

Technical Field

[0001] The invention relates to the technical field of coke oven gas purification, and in particular to a pretreatment system and method for deep purification of coke oven gas. Background Art

[0002] Coke oven gas is an important by-product obtained during the coking process. In recent years, the research on the composition of coke oven gas has been quite mature. Coke oven gas is a medium calorific value gas, with a hydrogen content of 50% to 60% and a methane content of 22% to 24%, which contains huge utilization value. A large amount of coke oven gas is produced while producing coke. If it is calculated that 430 cubic meters of coke oven gas is produced for 1 ton of coke, the annual coke oven gas production in my country is basically maintained at 180 billion cubic meters, of which about 45-50% of the coke oven gas returns to the coke oven, and the remaining coke oven gas is equivalent to more than twice the annual gas transmission capacity of the national "West-East Gas Transmission". Therefore, how to recycle and utilize coke oven gas is of great significance to the realization of resource recycling and sustainable economic development. Before the comprehensive utilization of coke oven gas, the purification of coke oven gas has become a top priority.

[0003] When the coke oven gas is comprehensively utilized to produce chemicals, the accuracy of desulfurization, naphthalene removal and other impurities is not enough to ensure the safe, stable, normal, full and optimal operation of the subsequent system, which is mainly manifested in the following three aspects:

[0004] (1) Excessive sulfur and ammonia content in coke oven gas affects the normal operation of subsequent purification and synthesis.

[0005] Generally, when coke oven gas is used only as fuel gas, H2S is required to be less than 500mg / Nm 3 , ammonia content is less than 100mg / Nm 3 However, in actual operation, acid gas and ammonia sometimes exceed the standard, affecting the stable operation of the system. With the expansion of coking scale and industrial agglomeration, coke oven gas has become an important chemical raw material gas. The change in the use of coke oven gas has caused the original design indicators to be far from meeting the current usage requirements.

[0006] (2) The tar and naphthalene contained in coke oven gas seriously affect the normal operation of the compressor. The main reason is that the coke oven gas contains high levels of tar and naphthalene. When compressed, the temperature rises and the tar gasifies and forms coke; and the naphthalene condenses and crystallizes, causing naphthalene blockage in the compressor, making it impossible for the compressor to operate normally, and even forced to stop for repairs. Sometimes the compressor has to be stopped for emergency repairs after only 1-2 days of operation, making production very passive. It is often a situation where 1 is in operation and 2 are on standby or 1 is in operation and 3 are on standby.

[0007] (3) Due to the abnormal coarse desulfurization, the desulfurizer of fine desulfurization fails prematurely, affecting the production operation, mainly due to sulfur breakthrough, and the desulfurizer is forced to be replaced in advance. As a result, the desulfurizer is frequently replaced, and the operating cost increases. Summary of the invention

[0008] In order to solve the technical problems that impurities in coke oven gas before comprehensive utilization will affect the stable operation of the subsequent system, cause compressor blockage, and cause the desulfurization agent of fine desulfurization to fail prematurely and increase operating costs, the present invention provides a pretreatment system and method for deep purification of coke oven gas.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0010] A pretreatment system for deep purification of coke oven gas comprises a pre-wash tower, a four-phase separator, a circulation pump and a heat exchanger, wherein the pre-wash tower is a supergravity rotating device, and the four-phase separator is a horizontal three-weir type gas-liquid-liquid-liquid separator, wherein: the gas phase inlet of the pre-wash tower is connected to the coke oven gas pipeline after benzene is eluted, the liquid phase outlet of the pre-wash tower is connected to the feed port of the four-phase separator, the intermediate phase fluid outlet of the four-phase separator is connected to the liquid inlet of the circulation pump, the liquid outlet of the circulation pump is connected to the liquid inlet of the heat exchanger, and the liquid outlet of the heat exchanger is connected to the liquid phase inlet of the pre-wash tower.

[0011] Optionally, the pre-wash tower includes a transmission device, a rotating shaft and a pre-wash shell, the transmission device is connected to one end of the rotating shaft, and the other end of the rotating shaft is connected to a rotor, the rotor is arranged in the middle and lower part of the inner cavity of the pre-wash shell, the top middle of the pre-wash shell is connected to a gas outlet, the bottom of the pre-wash shell is connected to a liquid phase outlet, the bottom of one side of the pre-wash shell is connected to a gas phase inlet, the middle and upper part of the other side of the pre-wash shell is connected to a liquid phase inlet, the liquid phase inlet is connected to an L-shaped liquid pipeline, the vertical pipe of the L-shaped liquid pipeline extends to the middle of the rotor, and a plurality of liquid phase nozzles are installed on the vertical pipe of the L-shaped liquid pipeline, a demister is provided at the top of the inner cavity of the pre-wash shell, a partition plate is installed between the bottom of the demister and the top of the rotor, the middle of the top of the rotor and the partition plate are sealed by a first sealing gasket, the middle of the bottom of the rotor and the rotating shaft are sealed by a second sealing gasket and a third sealing gasket on both sides, and the inside of the rotor is filled with a packing layer.

[0012] Optionally, the four-phase separator includes a separation shell, and the inner cavity of the separation shell is divided into an inlet section I, a sedimentation separation section II and a collection section III from left to right; the inlet section I is provided with a gas-liquid separator, a baffle and a calming plate, the feed port is arranged outside the separation shell and connected to the top of the separation shell, the gas-liquid separator is installed below the feed port, the bottom end of the calming plate is connected to the bottom of the separation shell, the top end of the baffle is connected to the top of the separation shell and is located between the gas-liquid separator and the calming plate; the sedimentation separation section II is installed with a coalescer; the collection section III is provided with a heavy phase fluid overflow weir, a heavy phase fluid collecting tank, a light phase fluid collecting tank and an intermediate phase fluid overflow weir, the heavy phase fluid overflow weir is arranged on one side of the coalescer and connected to the bottom of the separation shell, the top of the heavy phase fluid collecting tank is connected to the bottom of the separation shell and is located between the coalescer and the heavy phase fluid overflow weir, a first liquid level gauge is respectively installed on the top and bottom of the side wall of the heavy phase fluid collecting tank, and the bottom of the heavy phase fluid collecting tank is connected to the heavy phase fluid outlet, a second liquid level gauge is respectively installed on the top and bottom of the separation shell above the heavy phase fluid collecting tank, the light phase fluid collecting tank is arranged on one side of the heavy phase fluid overflow weir, the front wall of the light phase fluid collecting tank is the light phase fluid overflow weir, the height of the light phase fluid overflow weir is lower than the height of the rear wall of the light phase fluid collecting tank, a third liquid level gauge is respectively arranged on the top and bottom of the light phase fluid collecting tank, the bottom of the light phase fluid collecting tank is connected with the light phase fluid outlet, the light phase fluid outlet is located outside the separation shell, a demister is arranged above the light phase fluid collecting tank, the gas phase outlet is arranged outside the separation shell and is connected with the demister, the intermediate phase fluid overflow weir is arranged on one side of the light phase fluid collecting tank and is connected to the bottom of the separation shell, the intermediate phase fluid overflow weir and the space at the tail of the separation shell form an intermediate phase fluid collecting tank, a fourth liquid level gauge is respectively arranged on the top and bottom of one side of the intermediate phase fluid overflow weir, and the bottom of the separation shell on one side of the intermediate phase fluid overflow weir is connected with the intermediate phase fluid outlet.

[0013] Optionally, the length ratio of the inlet section I, the sedimentation separation section II and the collection section III is 1:3.2-4.2:2.

[0014] Optionally, the top of the calming plate is at the same horizontal plane as the second liquid level gauge located at the top of the separation shell; the bottom of the baffle is 400-500mm higher than the top of the calming plate, and the bottom of the baffle is not less than 200mm lower than the bottom of the gas-liquid separator.

[0015] Optionally, the height of the coalescer is the same as the height of the light phase fluid overflow weir, the height of the heavy phase fluid overflow weir is 200-500 mm higher than the bottom of the light phase fluid collecting tank, the height of the light phase fluid overflow weir is 1 / 2-3 / 4 of the diameter of the four-phase separator, the rear wall height of the light phase fluid collecting tank is 200 mm higher than the bottom of the demister, and the height of the intermediate phase fluid overflow weir is 20-100 mm lower than the height of the light phase fluid overflow weir.

[0016] A pretreatment method for deep purification of coke oven gas, the pretreatment method adopts the above-mentioned pretreatment system for deep purification of coke oven gas, and comprises the following steps:

[0017] S1, introducing the coke oven gas after benzene removal and the gas scrubber into the pre-wash tower through the gas phase inlet and the liquid phase inlet of the pre-wash tower respectively;

[0018] S2, in the pre-wash tower, the gas scrubber is evenly distributed through the liquid phase nozzle and enters the packing layer. Under the action of the transmission device, the rotating shaft and the rotor, the gas scrubber is split into liquid micro-elements and countercurrently contacts the coke oven gas after the benzene is eluted to remove impurities in the coke oven gas after the benzene is eluted;

[0019] S3, the coke oven gas after impurities are removed is defoamed by a demister to obtain pretreated coke oven gas, and the gas scrubber after impurities are removed is thrown to the inner wall of the pre-washing shell and flows into the four-phase separator from the liquid phase outlet;

[0020] S4, the four-phase separator separates the gas-liquid separation of the gas scrubber after impurities are removed. The separated intermediate phase is used as the gas scrubber after being pressurized by the circulating pump and heated to 15-20°C by the heat exchanger. The separated light phase and heavy phase are sent to the pipe area as products, and the separated gas phase is collected and processed.

[0021] Optionally, the operating conditions of the pre-wash tower are: operating temperature 15-20°C, operating pressure 3-6 kPa, filler specific surface area 500-4000m 2 / m 3 , packing rotation frequency is 30~60Hz, and gas-liquid ratio is 1000~6000.

[0022] Optionally, the porosity of the packing layer is 80% to 99%; the packing of the packing layer adopts large corrugated wire mesh packing and small corrugated wire mesh packing, and a small corrugated wire mesh packing with a length of 5% to 10% of the radius of the pre-wash shell is arranged near the rotating shaft, the average pore size of the large corrugated wire mesh packing is 5 to 10 mm, and the average pore size of the small corrugated wire mesh packing is 1 to 5 mm.

[0023] Optionally, the coal gas scrubber is one or a combination of two or more of desalted water, methanol, ethanol, crude benzene, wash oil and tar.

[0024] The beneficial effects of the present invention are:

[0025] By setting a pre-washing tower, a four-phase separator, a circulating pump and a heat exchanger, and setting the pre-washing tower as a supergravity rotating device, the coke oven gas after benzene washing can be removed by supergravity rotating technology in the pre-washing tower. The system and method can deeply remove harmful substances such as dust, benzene, tar, naphthalene, ammonia and sulfur in the coke oven gas after benzene washing, solve the problem that the excessive sulfur and ammonia in the coke oven gas will affect the stable operation of the subsequent system, and can improve the stability of the system operation; it also solves the problem that the tar and naphthalene in the coke oven gas will cause the compression system to be blocked, and avoids the blockage abnormality that may be caused in the subsequent section; it also solves the problem that the desulfurization agent of the fine desulfurization will fail prematurely and increase the operating cost due to abnormal rough desulfurization in the traditional process, meets the requirements of pressurized transportation of coke oven gas and subsequent deep purification, and achieves the purpose of purification required by the production chemical synthesis system. The present invention has the advantages of low investment, small equipment volume and floor space, high efficiency in removing impurities such as tar dust and naphthalene in coke oven gas, low energy consumption, and high washing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the system composition of the present invention.

[0027] Figure 2 yes Figure 1 Schematic diagram of the structure of the pre-wash tower.

[0028] Figure 3 yes Figure 1 Schematic diagram of the structure of the four-phase separator. DETAILED DESCRIPTION

[0029] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0030] like Figure 1 As shown, an embodiment of the present invention provides a pretreatment system for deep purification of coke oven gas, which includes a pre-wash tower 1, a four-phase separator 2, a circulating pump 3 and a heat exchanger 4, wherein the pre-wash tower 1 is a supergravity rotating device, and the four-phase separator 2 is a horizontal three-weir type gas-liquid-liquid-liquid separator, wherein: the gas phase inlet 103 of the pre-wash tower 1 is connected to the coke oven gas pipeline after benzene is eluted, the liquid phase outlet 102 of the pre-wash tower 1 is connected to the feed port 201 of the four-phase separator 2, the intermediate phase fluid outlet 205 of the four-phase separator 2 is connected to the liquid inlet of the circulating pump 3, the liquid outlet of the circulating pump 3 is connected to the liquid inlet of the heat exchanger 4, and the liquid outlet of the heat exchanger 4 is connected to the liquid phase inlet 109 of the pre-wash tower 1.

[0031] The system of the present invention is applied before the deep purification (desulfurization) of coke oven gas, that is, pre-treatment is carried out after the initial cooling, electrostatic tar capture, pre-cooling, desulfurization, intermediate cooling, ammonia removal, final cooling and benzene elution of the coke oven gas to remove impurities such as dust, benzene, tar, naphthalene, ammonia and various forms of sulfur contained in the coke oven gas after the benzene elution, so as to meet the pressure boosting and transportation of the coke oven gas and the subsequent deep purification, and achieve the purification needs of the production chemical synthesis system.

[0032] Alternatively, if Figure 2 As shown, the pre-wash tower 1 includes a transmission device 101, a rotating shaft 115 and a pre-wash shell 108, the transmission device 101 is connected to one end of the rotating shaft 115, the other end of the rotating shaft 115 is connected to a rotor 104, the rotor 104 is arranged in the middle and lower part of the inner cavity of the pre-wash shell 108, the top middle of the pre-wash shell 108 is connected to a gas outlet 107, the bottom of the pre-wash shell 108 is connected to a liquid phase outlet 102, the bottom of one side of the pre-wash shell 108 is connected to a gas phase inlet 103, the middle and upper part of the other side of the pre-wash shell 108 is connected to a liquid phase inlet 109, and the liquid phase inlet 109 is connected to L shaped liquid pipeline, the vertical pipe of the L-shaped liquid pipeline extends to the middle of the rotor 104, a plurality of liquid phase nozzles 111 are installed on the vertical pipe of the L-shaped liquid pipeline, a demister 106 is provided on the top of the inner cavity of the pre-wash shell 108, a partition plate 105 is installed between the bottom of the demister 106 and the top of the rotor 104, the middle of the top of the rotor 104 and the partition plate 105 are sealed by a first sealing gasket 110, the middle of the bottom of the rotor 104 and the rotating shaft 115 are sealed by a second sealing gasket 112 and a third sealing gasket 113 respectively, and the inside of the rotor 104 is filled with a packing layer 114.

[0033] Alternatively, if Figure 3As shown, the four-phase separator 2 includes a separation shell 218, and the inner cavity of the separation shell 218 is divided into an inlet section I, a sedimentation separation section II and a collection section III from left to right; the inlet section I is provided with a gas-liquid separator 206, a baffle 207 and a calming plate 208, the feed inlet 201 is arranged outside the separation shell 218 and connected to the top of the separation shell 218, the gas-liquid separator 206 is installed below the feed inlet 201, the bottom end of the calming plate 208 is connected to the bottom of the separation shell 218, the top end of the baffle 207 is connected to the top of the separation shell 218 and is located between the gas-liquid separator 206 and the calming plate 208; the sedimentation separation Section II is equipped with a coalescer 209; the collection section III is provided with a heavy phase fluid overflow weir 217, a heavy phase fluid collecting tank 219, a light phase fluid collecting tank 220 and an intermediate phase fluid overflow weir 216, the heavy phase fluid overflow weir 217 is arranged on one side of the coalescer 209 and connected to the bottom of the separation shell 218, the top of the heavy phase fluid collecting tank 219 is connected to the bottom of the separation shell 218 and is located between the coalescer 209 and the heavy phase fluid overflow weir 217, the top and bottom of the side wall of the heavy phase fluid collecting tank 219 are respectively equipped with a first liquid level gauge 213, and the bottom of the heavy phase fluid collecting tank 219 is connected to the heavy phase fluid outlet 2 03, a second level gauge 212 is installed on the top and bottom of the separation shell 218 above the heavy phase fluid collection tank 219, the light phase fluid collection tank 220 is arranged on one side of the heavy phase fluid overflow weir 217, the front wall of the light phase fluid collection tank 220 is the light phase fluid overflow weir 214, the height of the light phase fluid overflow weir 214 is lower than the height of the rear wall 215 of the light phase fluid collection tank 220, a third level gauge 210 is installed on the top and bottom of the light phase fluid collection tank 220, the bottom of the light phase fluid collection tank 220 is connected to the light phase fluid outlet 204, and the light phase fluid outlet 204 is located in the separation shell 21 8 outside, a demister 222 is arranged above the light phase fluid collecting tank 220, the gas phase outlet 202 is arranged outside the separation shell 218 and connected to the demister 222, the intermediate phase fluid overflow weir 216 is arranged on one side of the light phase fluid collecting tank 220 and connected to the bottom of the separation shell 218, the intermediate phase fluid overflow weir 216 and the space at the tail of the separation shell 218 form an intermediate phase fluid collecting tank 221, a fourth liquid level gauge 211 is respectively arranged at the top and bottom of one side of the intermediate phase fluid overflow weir 216, and the bottom of the separation shell 218 on one side of the intermediate phase fluid overflow weir 216 is connected to the intermediate phase fluid outlet 205.

[0034] Among them, the gas-liquid separator 206 and the calming plate 208 are conventional components of the inlet section I. The main function of the gas-liquid separator 206 is to realize gas-liquid pre-separation. There are many forms in practical applications. Its function is to evenly distribute or redistribute the liquid on the top of the packing or at a certain height to increase the effective surface of mass transfer and heat transfer, improve the contact between phases, and thus improve the separation efficiency of the tower. The main function of the calming plate 208 is to slow down the two-phase fluctuations in the liquid phase area of ​​the inlet section I. It also has the function of liquid-liquid-liquid pre-separation, but it mainly suppresses the fluctuations to provide stable operating conditions for the sedimentation separation section II. The coalescer 209 mainly improves the separation efficiency by promoting the coalescence of the light phase (such as oil droplets) on the plate surface, and also has the function of suppressing the fluctuations in the liquid phase area of ​​the sedimentation separation section II.

[0035] Optionally, the length ratio of the inlet section I, the sedimentation separation section II and the collection section III is 1:3.2-4.2:2.

[0036] Optionally, the top of the calming plate 208 is at the same horizontal plane as the second liquid level gauge 212 located at the top of the separation shell 218; the bottom of the baffle 207 is 400-500mm higher than the top of the calming plate 208, and the bottom of the baffle 207 is not less than 200mm lower than the bottom of the gas-liquid separator 206.

[0037] Optionally, the height of the coalescer 209 is the same as the height (H1) of the light phase fluid overflow weir 214, the height of the heavy phase fluid overflow weir 217 is 200-500 mm higher than the bottom of the light phase fluid collecting tank 220, the height of the light phase fluid overflow weir 214 is 1 / 2-3 / 4 of the diameter of the four-phase separator, the height (H2) of the rear wall 215 of the light phase fluid collecting tank 220 is 200 mm higher than the bottom of the demister 222, and the height (H3) of the intermediate phase fluid overflow weir 216 is 20-100 mm lower than the height of the light phase fluid overflow weir 214.

[0038] By setting three overflow weir plates, namely, the heavy phase fluid overflow weir 217, the light phase fluid overflow weir 214 and the intermediate phase fluid overflow weir 216, and three liquid phase collecting tanks, namely, the heavy phase fluid collecting tank 219, the light phase fluid collecting tank 220 and the intermediate phase fluid collecting tank 221, in the collection section III, the length of the collection section III of the four-phase separator 2 is greater than that of the ordinary separator. However, due to such a setting, the liquid-liquid interface during the operation is better controlled, thereby ensuring the stable progress of the separation process, thereby reducing or avoiding the influence of the operating condition fluctuation on the sedimentation separation section II process. The control of the liquid-liquid interface of the four-phase separator 2 in the embodiment of the present invention comes from two aspects: first, the three overflow weir plates and the three liquid phase collecting tank structures make the liquid-liquid interface simultaneously controlled by the static pressure of the light phase / intermediate phase and the heavy phase fluid, so it is relatively stable; second, the light phase fluid collecting tank 220 and the intermediate phase fluid collecting tank 221 provide a buffer space for the fluctuation of the upstream and downstream (inlet and outlet) flow during the operation, thereby reducing or avoiding the influence of the operating condition fluctuation on the sedimentation separation process. By providing components such as the calming plate 208 and the coalescer 209, a lower lateral flow velocity is ensured so that the fluid in the liquid phase has sufficient residence time to achieve liquid-liquid-liquid sedimentation separation, which is beneficial to the sedimentation or buoyancy of the dispersed phase, reduces the fluctuation of the liquid phase, shortens the separation time, and reduces the size of the equipment.

[0039] All the inventions adopted Figure 3 The four-phase separator 2 shown is designed by comprehensively considering the factors affecting the pressure distribution at the end of the sedimentation separation section II under actual separation conditions, including: the height of the light phase fluid overflow weir 214 and the height difference of the three weir plates, the liquid layer thickness and liquid layer flow rate at the overflow weir top and the flow resistance at the bottom of the light phase collection tank 220.

[0040] The embodiment of the present invention further provides a pretreatment method for deep purification of coke oven gas, the pretreatment method adopts the above-mentioned pretreatment system for deep purification of coke oven gas, and comprises the following steps:

[0041] S1, the coke oven gas after benzene is eluted and the gas scrubber are introduced into the pre-wash tower 1 through the gas phase inlet 103 and the liquid phase inlet 109 of the pre-wash tower 1 respectively.

[0042] After benzene is removed, the coke oven gas contains impurities such as dust, benzene, tar, naphthalene, ammonia and various forms of sulfur. Among them, the tar dust content is 5-15 mg / m 3 , naphthalene content 10~200mg / m 3 , ammonia content 15~100mg / m 3 , sulfur content is less than 500mg / m 3 .

[0043] S2, in the pre-wash tower 1, the gas scrubber is evenly distributed through the liquid phase nozzle 111 and then enters the packing layer 114. Under the action of the transmission device 101, the rotating shaft 115 and the rotor 104, the gas scrubber is split into liquid micro-elements (liquid film, liquid filaments and liquid droplets) and countercurrently contacts with the coke oven gas after benzene is eluted to remove impurities in the coke oven gas after benzene is eluted.

[0044] Since the pre-wash tower 1 is a super gravity rotating device, the embodiment of the present invention uses super gravity rotating technology to remove impurities, and the cutting particle size of the gravity rotating technology reaches 10 -8 The particle size of the gas scrubber after passing through the packing layer 114 almost reaches the classification level, and then it is gathered in the supergravity rotating device and removed together with the impurities. The supergravity rotating technology can enhance the washing effect and reduce the particle size cut size of the washing. At the same time, through the liquid phase spray and supergravity, the droplet distribution is more uniform, and the contact surface with the impurities in the coke oven gas is larger, thereby improving the elution effect. The supergravity rotating device has the characteristics of good particle capture effect, small gas phase pressure drop, and the rotating packing is not easy to be blocked, so as to achieve the deep removal of harmful substances such as dust, benzene, tar, naphthalene and ammonia in the coke oven gas after elution of benzene, meet the coke oven gas pressurization and subsequent deep purification, and achieve the purpose of purification of the production chemical synthesis system.

[0045] Practice has proved that after treatment in this way, the dust collection efficiency reaches more than 99%, and particles larger than 3μm can be completely removed; the removal rate of naphthalene is more than 80%; the removal rate of tar and dust is more than 60%, the removal rate of organic sulfur is more than 85%; the removal rate of ammonia is more than 50%; and the removal rate of benzene is more than 50%.

[0046] S3, the coke oven gas after impurities are removed is defoamed by the demister 106 to obtain pretreated coke oven gas, and the gas scrubber after impurities are removed is thrown to the inner wall of the pre-washing shell 108 and flows into the four-phase separator 2 from the liquid phase outlet 102.

[0047] The gas scrubber after impurities removal is rich in impurities such as tar dust, naphthalene, and ammonia.

[0048] S4, the four-phase separator 2 performs gas-liquid separation on the gas scrubber after impurities are removed, and the separated intermediate phase is used as the gas scrubber after being pressurized by the circulation pump 3 and heat-exchanged to 15-20°C by the heat exchanger 4, and then circulated as the gas scrubber. The separated light phase and heavy phase are sent to the pipe area as products, and the separated gas phase is collected and processed.

[0049] Optionally, the operating conditions of the pre-wash tower 1 are: operating temperature 15-20°C, operating pressure 3-6 kPa, filler specific surface area 500-4000m 2 / m 3, packing rotation frequency is 30~60Hz, and gas-liquid ratio is 1000~6000.

[0050] Optionally, the porosity of the packing layer 114 is 80% to 99%; the packing of the packing layer 114 is made of large corrugated wire mesh packing and small corrugated wire mesh packing. A small corrugated packing having a length of 5% to 10% of the radius of the pre-wash shell 108 is arranged near the rotating shaft 115, preferably 5% to 8%. The average pore size of the large corrugated wire mesh packing is 5 to 10 mm, preferably 4 to 8 mm; the average pore size of the small corrugated wire mesh packing is 1 to 5 mm, preferably 2 to 4 mm. This packing method is conducive to the uniform atomization of the liquid phase washing liquid and improves the capture effect of impurities. The large corrugated packing can reduce the gas-liquid phase resistance and improve the anti-clogging ability of the packing.

[0051] Optionally, the coal gas scrubber is one or a combination of two or more of desalted water, methanol, ethanol, crude benzene, wash oil and tar.

[0052] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A coke oven gas processing system, characterized in that: The coke oven gas first passes through a pretreatment system of primary cooling, electric tar capture, precooling, desulfurization, intermediate cooling, ammonia removal, final cooling and benzene elution to remove dust, benzene, tar, naphthalene, ammonia and various forms of sulfur impurities contained in the coke oven gas after benzene elution. The coke oven gas after benzene elution then enters a deep treatment system. The deep treatment system comprises a pre-wash tower (1), a four-phase separator (2), a circulation pump (3) and a heat exchanger (4). The pre-wash tower (1) is a super gravity rotating device, and the four-phase separator (2) is a horizontal three-weir type gas- A liquid-liquid-liquid separator, wherein: the gas phase inlet (103) of the pre-wash tower (1) is connected to the coke oven gas pipeline after benzene is eluted, the liquid phase outlet (102) of the pre-wash tower (1) is connected to the feed port (201) of the four-phase separator (2), the intermediate phase fluid outlet (205) of the four-phase separator (2) is connected to the liquid inlet of the circulation pump (3), the liquid outlet of the circulation pump (3) is connected to the liquid inlet of the heat exchanger (4), and the liquid outlet of the heat exchanger (4) is connected to the liquid phase inlet (109) of the pre-wash tower (1); The pre-wash tower (1) comprises a transmission device (101), a rotating shaft (115) and a pre-wash shell (108); the transmission device (101) is connected to one end of the rotating shaft (115); the other end of the rotating shaft (115) is connected to a rotor (104); the rotor (104) is arranged in the middle and lower part of the inner cavity of the pre-wash shell (108); the middle of the top of the pre-wash shell (108) is connected to a gas outlet (107); the bottom of the pre-wash shell (108) is connected to a liquid phase outlet (102); the bottom of one side of the pre-wash shell (108) is connected to a gas phase inlet (103); the middle and upper part of the other side of the pre-wash shell (108) is connected to a liquid phase inlet (109); the liquid phase inlet (109) is connected to the liquid phase outlet (102); An L-shaped liquid pipeline is provided, wherein the vertical pipe of the L-shaped liquid pipeline extends to the middle of the rotor (104), and a plurality of liquid phase nozzles (111) are installed on the vertical pipe of the L-shaped liquid pipeline. A demister (106) is provided at the top of the inner cavity of the pre-wash shell (108), and a partition plate (105) is installed between the bottom of the demister (106) and the top of the rotor (104). The middle of the top of the rotor (104) and the partition plate (105) are sealed by a first sealing gasket (110), and the two sides of the middle of the bottom of the rotor (104) and the rotating shaft (115) are sealed by a second sealing gasket (112) and a third sealing gasket (113) respectively. The inside of the rotor (104) is filled with a packing layer (114); The four-phase separator (2) comprises a separation shell (218), wherein the inner cavity of the separation shell (218) is divided from left to right into an inlet section (I), a sedimentation separation section (II) and a collection section (III); The inlet section (I) is provided with a gas-liquid separator (206), a baffle (207) and a calming plate (208); the feed port (201) is provided outside the separation shell (218) and is connected to the top of the separation shell (218); the gas-liquid separator (206) is installed below the feed port (201); the bottom end of the calming plate (208) is connected to the bottom of the separation shell (218); the top end of the baffle (207) is connected to the top of the separation shell (218) and is located between the gas-liquid separator (206) and the calming plate (208); the sedimentation separation section (II) is provided with a coalescer (209); the collection section (III) is provided with a heavy phase fluid overflow weir (217), a heavy phase A fluid collecting tank (219), a light phase fluid collecting tank (220) and an intermediate phase fluid overflow weir (216); a heavy phase fluid overflow weir (217) is arranged on one side of the coalescer (209) and connected to the bottom of the separation shell (218); a top of the heavy phase fluid collecting tank (219) is connected to the bottom of the separation shell (218) and is located between the coalescer (209) and the heavy phase fluid overflow weir (217); a first liquid level gauge (213) is respectively installed on the top and bottom of the side wall of the heavy phase fluid collecting tank (219); a heavy phase fluid outlet (203) is connected to the bottom of the heavy phase fluid collecting tank (219); and a separation shell (218) above the heavy phase fluid collecting tank (219) is provided. 8) A second liquid level meter (212) is installed at the top and bottom, respectively; the light phase fluid collection tank (220) is arranged on one side of the heavy phase fluid overflow weir (217); the front wall of the light phase fluid collection tank (220) is the light phase fluid overflow weir (214); the height of the light phase fluid overflow weir (214) is lower than the height of the rear wall (215) of the light phase fluid collection tank (220); a third liquid level meter (210) is installed at the top and bottom of the light phase fluid collection tank (220); the bottom of the light phase fluid collection tank (220) is connected to a light phase fluid outlet (204); the light phase fluid outlet (204) is located outside the separation shell (218); the light phase fluid collection tank (220) is provided with a light phase fluid outlet (204); the light phase fluid outlet (204) is located outside the separation shell (218); A demister (222) is arranged above the separation shell (20), a gas phase outlet (202) is arranged outside the separation shell (218) and is connected to the demister (222), an intermediate phase fluid overflow weir (216) is arranged on one side of the light phase fluid collection tank (220) and is connected to the bottom of the separation shell (218), the intermediate phase fluid overflow weir (216) and the space at the tail of the separation shell (218) form an intermediate phase fluid collection tank (221), a fourth liquid level gauge (211) is respectively arranged at the top and bottom of one side of the intermediate phase fluid overflow weir (216), and the bottom of the separation shell (218) on one side of the intermediate phase fluid overflow weir (216) is connected to the intermediate phase fluid outlet (205).

2. The coke oven gas processing system according to claim 1, characterized in that: The length ratio of the inlet section (I), the sedimentation separation section (II) and the collection section (III) is 1:3.2-4.2:

2.

3. The coke oven gas processing system according to claim 1, characterized in that: The top of the calming plate (208) is at the same horizontal plane as the second liquid level gauge (212) located at the top of the separation shell (218); the bottom of the baffle (207) is 400-500 mm higher than the top of the calming plate (208), and the bottom of the baffle (207) is not less than 200 mm lower than the bottom of the gas-liquid separator (206).

4. The coke oven gas processing system according to claim 1, characterized in that: The height of the coalescer (209) is the same as the height of the light phase fluid overflow weir (214); the height of the heavy phase fluid overflow weir (217) is 200-500 mm higher than the bottom of the light phase fluid collecting tank (220); the height of the light phase fluid overflow weir (214) is 1 / 2-3 / 4 of the diameter of the four-phase separator; the height of the rear wall (215) of the light phase fluid collecting tank (220) is 200 mm higher than the bottom of the demister (222); and the height of the intermediate phase fluid overflow weir (216) is 20-100 mm lower than the height of the light phase fluid overflow weir (214).

5. A pretreatment method for deep purification of coke oven gas, the pretreatment method adopting the coke oven gas treatment system according to any one of claims 1 to 4, characterized in that: The steps include: S1, introducing the coke oven gas after benzene is eluted and the gas scrubber into the pre-wash tower (1) through the gas phase inlet (103) and the liquid phase inlet (109) of the pre-wash tower (1) respectively; S2, in the pre-wash tower (1), the gas scrubber is evenly distributed through the liquid phase nozzle (111) and then enters the packing layer (114). Under the action of the transmission device (101), the rotating shaft (115) and the rotor (104), the gas scrubber is split into liquid micro-elements and countercurrently contacts the coke oven gas after benzene is eluted, thereby removing impurities in the coke oven gas after benzene is eluted; S3, the coke oven gas after impurities are removed is passed through the demister (106) to obtain pre-treated coke oven gas, and the gas scrubber after impurities are removed is thrown onto the inner wall of the pre-washing shell (108) and flows into the four-phase separator (2) from the liquid phase outlet (102); S4, the four-phase separator (2) performs gas-liquid separation on the gas scrubber after impurities are removed, and the separated intermediate phase is used as the gas scrubber after being pressurized by the circulation pump (3) and heat-exchanged to 15-20°C by the heat exchanger (4) and then circulated as the gas scrubber. The separated light phase and heavy phase are sent to the pipe area as products, and the separated gas phase is collected and processed.

6. The pretreatment method for deep purification of coke oven gas according to claim 5, characterized in that: The operating conditions of the pre-wash tower (1) are: operating temperature 15-20°C, operating pressure 3-6 kPa, filler specific surface area 500-4000 m2 / m3, filler rotation frequency 30-60 Hz, and gas-liquid ratio 1000-6000.

7. The pretreatment method for deep purification of coke oven gas according to claim 5, characterized in that: The porosity of the filler layer (114) is 80% to 99%; The packing of the packing layer (114) is composed of large corrugated wire mesh packing and small corrugated wire mesh packing. A small corrugated wire mesh packing having a length of 5% to 10% of the radius of the pre-washing shell (108) is arranged near the rotating shaft (115). The average pore size of the large corrugated wire mesh packing is 5 to 10 mm, and the average pore size of the small corrugated wire mesh packing is 1 to 5 mm.

8. The pretreatment method for deep purification of coke oven gas according to any one of claims 5 to 7, characterized in that: The gas scrubber is one or a combination of two or more of desalted water, methanol, ethanol, crude benzene, washing oil and tar.

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