Industrial waste gas treatment device and method

Abstract

The invention discloses an industrial waste gas treatment device and an industrial waste gas treatment method, which are particularly used for desorption regeneration of adsorption towers containing benzene and sulfides, the device comprises at least three adsorption towers, a flash tank, a desorption steam condenser, a steam compressor, a heater, a benzene recovery sub-device and a waste water treatment sub-device, circularly switching for use; the device can also comprise a vacuum desorption pipeline. According to the industrial waste gas treatment method disclosed by the invention, desorption regeneration of the adsorption tower is carried out by taking desulfurization and benzene recovery as targets, and in the cooling process of the adsorption tower, two modes of saturated steam cooling and negative pressure desorption steam cooling are combined, so that low-energy-consumption, rapid and deep cooling is realized, and low-energy-consumption, rapid and deep cooling is realized. According to the device and the method, the energy utilization efficiency is remarkably improved through maximum heat recovery, particularly steam-water-steam energy cyclic utilization, and material resource utilization is realized by combining the device and the method for wastewater treatment and benzene recovery.

Description

Technical Field

[0001] The present invention belongs to the field of environmental protection and energy conservation, and specifically relates to an industrial waste gas treatment device and method based on coke oven gas vapor desorption. Background Art

[0002] At present, the coke oven gas produced in the coking production of chemical enterprises contains a large amount of sulfide, benzene and other impurities. The usual waste gas treatment and desorption scheme is to heat the coke oven gas and then pass it into an adsorption tower for desorption. The desorbed gas carries the desorbed sulfide, benzene and other impurities into the spray-cooled adsorption tower, which is then transported to the kiln of the building materials factory for incineration after spray cooling.

[0003] The problem with this approach is that the local kilns cannot absorb such a large amount of sulfide, resulting in kiln emissions exceeding the standard. This treatment method needs to be upgraded.

[0004] Through many production experiments, it can be found that the desorbed gas contains a large amount of benzene, and the economic and social benefits brought by recovering the benzene in the desorbed gas are very considerable.

[0005] In addition, in terms of technical implementation, the desorption gas is coal gas and the boiling point of benzene is 80°C. This situation creates great difficulties for the company's benzene recovery work. Summary of the invention

[0006] In view of the above-mentioned technical problems, the present invention provides an industrial waste gas treatment device and method, including more than three adsorption towers connected in parallel, combined with a steam compression, condensation system and a benzene recovery system, which can efficiently desorb and recover benzene, and realize the recycling of steam and heat. The industrial waste gas treatment device and method utilize the cooling process of the adsorption tower, and combine saturated steam cooling and low-pressure desorption steam cooling to achieve low-energy consumption, rapid deep cooling, and realize as much heat recovery as possible during the cooling process.

[0007] The technical solution of the present invention is: An industrial waste gas treatment device, comprising an adsorption tower, a flash tank, a desorption steam condenser, a steam compressor, a heater, a benzene recovery sub-device, a wastewater treatment sub-device and an adsorbent; The adsorption towers are arranged in more than three units and connected in parallel with each other. The adsorbent is installed in the towers. The adsorption towers have a first steam inlet and outlet, a second steam inlet and outlet, and a waste gas inlet; the first steam inlet and outlet is arranged at the upper part of the adsorption tower and is connected to the flash tank pipeline, the second steam inlet and outlet is arranged at the lower part of the adsorption tower and is connected to the steam inlet pipeline of the desorption steam condenser, the second steam inlet and outlet is connected to the cooling gas inlet pipeline through a valve, and the cooling gas inlet is introduced into low-temperature and low-pressure saturated steam; the waste gas inlet is externally connected to a waste gas pipeline, and the waste gas pipeline is introduced into the industrial waste gas to be treated.

[0008] Preferably, the adsorbent is a porous material with a high specific surface area for adsorbing impurity gases.

[0009] Preferably, the first steam inlet and outlet are arranged at the top of the adsorption tower.

[0010] Preferably, the waste gas inlet is arranged at the bottom of the adsorption tower, and further, the waste gas inlet is arranged at the bottom of the adsorption tower.

[0011] Preferably, the industrial waste gas to be treated is coke oven gas containing a large amount of impurities such as benzene and sulfide.

[0012] Preferably, the steam inlet of the desorption steam condenser is generally arranged at the top of the desorption steam condenser.

[0013] The water inlet of the flash tank is connected to the water outlet pipe of the wastewater treatment sub-device, a circulating pump is provided on the connecting pipe between the water outlet of the flash tank and the water inlet of the desorption steam condenser, the circulating water inlet of the flash tank and the circulating water outlet of the desorption steam condenser are connected through a pipe, the steam compressor and the heater are provided on the connecting pipe between the circulating water outlet of the flash tank and the first steam inlet and outlet of the adsorption tower, and the outlet of the steam compressor is connected to the inlet pipe of the heater.

[0014] Preferably, the water inlet of the flash tank is generally arranged at the bottom of the flash tank.

[0015] Preferably, the flash tank further has a compensating steam inlet, the compensating steam inlet is externally connected to a steam pipeline, and a regulating valve is provided on the steam pipeline.

[0016] Preferably, the flash tank has a wastewater outlet, the wastewater outlet is externally connected to a drain pipe, and the drain pipe is provided with a drain pump.

[0017] Preferably, the steam output from the flash separation in the flash tank is saturated steam.

[0018] The non-condensable gas outlet of the desorption steam condenser is connected to the pipeline of the benzene recovery sub-device, and the condensed water outlet of the desorption steam condenser is connected to the water inlet pipeline of the wastewater treatment sub-device.

[0019] Preferably, the desorption steam condenser is configured as a multi-stage condenser. In the first-stage condenser, the temperature of the circulating water is higher than the boiling point of benzene, and the outlet water temperature of the flash tank is configured to be 85-94°C.

[0020] Preferably, the benzene recovery sub-device includes a benzene liquid condenser, an oil-water separator, and a crude benzene tank; the inlet of the benzene liquid condenser is connected to the non-condensable gas outlet pipe of the desorption steam condenser, and the oil-water separator is provided on the connecting pipe between the benzene liquid condenser and the crude benzene tank.

[0021] Preferably, the industrial waste gas treatment device further comprises a wastewater treatment sub-device for treating sulfide-containing wastewater. The wastewater treatment sub-device comprises an ammonia water storage tank, an inclined plate oil separator, an air flotation tank and a filter, wherein the inclined plate oil separator is connected to the condensate outlet pipe of the desorption steam condenser through the ammonia water storage tank, the filter is connected to the inclined plate oil separator pipe through the air flotation tank, and the filter is externally connected to the water inlet of the flash tank.

[0022] Preferably, the steam after desorption is circulated into the desorption steam condenser and is cooled by the condenser to produce condensed water. This condensed water contains more impurities such as tar and naphthalene, and the pH value is acidic. After the conventional water treatment measures such as neutralization with ammonia water, oil separation, flocculation, and flotation, the water is circulated into the flash tank as water replenishment for the flash tank.

[0023] Preferably, the industrial waste gas treatment device also includes a vacuum desorption pipeline, one end of which is connected to the second steam inlet and outlet of the adsorption tower, and the other end is connected to the steam compressor inlet, and the vacuum desorption pipeline is provided with a pipeline valve and a regulating valve.

[0024] A method for treating industrial waste gas based on the above device includes the following process: After the adsorption reaches a certain adsorption rate, the adsorption tower switches to desorption regeneration. After the heating desorption state and the cooling state, the adsorption tower switches to the adsorption state again. At least three parallel adsorption towers are in the adsorption state, the heating desorption state, the cooling state, and are cyclically switched for use; The circulating water outlet of the flash tank is connected to the inlet pipeline of the steam compressor. The low-temperature and low-pressure saturated steam is compressed by the steam compressor and heated by the heater in turn to reach the pressure and temperature required for desorption. After entering the adsorption tower, it enters the heating desorption state; The high-temperature steam after desorption enters the desorption steam condenser through the pipeline. The desorption steam is condensed into liquid through the shell side of the desorption steam condenser, enters the wastewater treatment sub-device for purification to form circulating water, and re-enters the flash tank; The tube side of the desorption steam condenser transports circulating water, which is heated by steam and sprayed into the flash tank through the circulating water outlet pipe. Part of the circulating water is flashed into low-temperature and low-pressure steam, and the other part of the circulating water flows into the bottom of the flash tank after the flash steam takes out part of the heat, and is driven by a water pump to re-enter the desorption steam condenser for heating.

[0025] Preferably, the industrial waste gas treatment method further comprises the following cooling step: After the adsorption tower has passed the heating and desorption state, low-temperature and low-pressure saturated steam is introduced through the cooling gas inlet and the tower enters the cooling state. The steam flows through the adsorption tower and absorbs heat in the process to cool the adsorption tower. At this time, the first steam inlet and outlet of the adsorption tower is connected to the outlet of the steam compressor through a pipeline, and the high-temperature steam is used as a desorption gas to flow into another adsorption tower in the heating and desorption state for desorption.

[0026] Preferably, after the above cooling step, the following cooling step is also included: When the adsorption tower is cooled to the saturated steam temperature (usually slightly higher than the saturated steam temperature), stop introducing low-temperature and low-pressure saturated steam, open the vacuum desorption pipeline valve connected to the steam compressor inlet, and the steam compressor will pump the adsorption tower into negative pressure. Under the negative pressure state, the adsorption tower desorbs water. The process of desorption absorbs a lot of heat, so that the adsorption tower is further cooled to meet the conditions for re-entering the adsorption state; At this time, the adsorption tower and the flash tank are connected by a parallel pipeline, and the water vapor generated by the negative pressure desorption of the adsorption tower and the flash steam merge in front of the steam compressor inlet.

[0027] Beneficial effects: Compared with the prior art, the present invention realizes as much heat recovery as possible, especially the recycling of steam-water-steam, and realizes the recycling of resources in terms of materials and energy. Specifically, the industrial waste gas treatment method carries out desorption and regeneration of the adsorption tower with the goal of desulfurization and benzene recovery. The desorption gas medium is water vapor. By controlling the condensation process of water vapor, benzene and the like desorbed from the adsorbent are extracted and recovered; the desorption heat is recovered and recycled by heat recovery and negative pressure evaporation; in the cooling process of the adsorption tower, the heat is recovered by using high-pressure saturated steam to cool and re-integrate the recovered heat into another adsorption tower that is desorbing, thereby realizing heat recovery in the cooling process; by using negative pressure desorption, the adsorption tower that has been cooled by saturated steam (and adsorbed a certain amount of water at the same time) desorbs water, and the principle of heat absorption in the water desorption process is used to realize rapid cooling and deep cooling of the adsorption tower, and heat recovery is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the overall structure of an industrial waste gas treatment device of the present invention; In the figure: 1, adsorption tower; 1a, adsorption tower (adsorption state); 1b, adsorption tower (heating desorption state); 1c, adsorption tower (cooling state); 11, first steam inlet and outlet; 12, second steam inlet and outlet; 14, cooling gas inlet; 15, waste gas inlet; flash tank; 21, water inlet; 22, water outlet; 23, compensation steam inlet; 24, waste water outlet; 25, circulating water inlet; 26, circulating water outlet; 3, desorption steam condenser; 4, steam compressor; 5, heater; 6, vacuum desorption pipeline; 7, benzene recovery sub-unit; 71, benzene liquid condenser; 711, cooling water inlet; 712, non-condensable gas outlet; 72, oil-water separator; 73, crude benzene tank; 8, waste water treatment sub-unit; 81, ammonia water storage tank; 82, inclined plate oil separator; 83, flotation tank; 84, filter. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0030] It should be noted that the pressures described in the present invention are all absolute pressures.

[0031] The application site of the present invention is to adsorb impurities in coke oven gas. There are three adsorption towers on site for cyclic use. The adsorption towers are filled with adsorbents. The adsorbents can be porous materials with high specific surface areas such as molecular sieves, activated carbon, activated alumina, etc., which are used to adsorb gases containing impurities passing through the towers.

[0032] like Figure 1 As shown, an industrial waste gas treatment device includes an adsorption tower 1, a flash tank 2, a desorption steam condenser 3, a steam compressor 4, a heater 5, a vacuum desorption pipeline 6, a benzene recovery sub-device 7, and a wastewater treatment sub-device 8.

[0033] The adsorption tower 1 has a first steam inlet and outlet 11, a second steam inlet and outlet 12, a cooling gas inlet 14 and a waste gas inlet 15; the first steam inlet and outlet 11 is arranged at the upper part of the adsorption tower 1, and is connected to the flash tank 2 pipeline, the second steam inlet and outlet 12 is arranged at the lower part of the adsorption tower 1, and is connected to the steam inlet pipeline of the desorption steam condenser 3, the second steam inlet and outlet 12 of the adsorption tower 1 is connected to the cooling gas inlet 14 pipeline through a valve, and the cooling gas inlet 14 is introduced into the low-temperature and low-pressure saturated steam; the waste gas inlet 15 is externally connected to the waste gas pipeline, and the waste gas pipeline is introduced into the industrial waste gas to be treated.

[0034] The water inlet 21 of the flash tank 2 is connected to the water outlet pipeline of the wastewater treatment sub-device 8, a circulating pump is provided on the connecting pipeline between the water outlet 22 of the flash tank 2 and the water inlet of the desorption steam condenser 3, the circulating water inlet 25 of the flash tank 2 and the circulating water outlet of the desorption steam condenser 3 are connected through a pipeline, a steam compressor 4 and a heater 5 are provided on the connecting pipeline between the circulating water outlet 26 of the flash tank and the first steam inlet and outlet 11 of the adsorption tower, and the outlet of the steam compressor 4 is connected to the inlet pipeline of the heater 5; The flash tank 2 also has a compensating steam inlet 23 connected to an external steam pipeline, on which a regulating valve is provided; the flash tank 2 also has a waste water outlet 24 connected to an external drain pipe, on which a drain pump is provided.

[0035] The non-condensable gas outlet of the desorption steam condenser 3 is connected to the benzene recovery sub-device 7 through a pipeline, and the condensate water outlet of the desorption steam condenser 3 is connected to the water inlet pipeline of the wastewater treatment sub-device 8 .

[0036] The non-condensable gas cooled by the high-temperature circulating water of the flash tank enters the benzene liquid condenser, where the benzene is condensed into liquid. After oil-water separation, the separated crude benzene can be sold directly, which has considerable economic benefits.

[0037] The industrial waste gas treatment device also includes a benzene recovery sub-device 7, which includes a benzene liquid condenser 71, an oil-water separator 72, and a crude benzene tank 73; the inlet of the benzene liquid condenser 71 is connected to the non-condensable gas outlet pipeline of the desorption steam condenser 3, and an oil-water separator 72 is provided on the connecting pipeline between the benzene liquid condenser 71 and the crude benzene tank 73.

[0038] The benzene liquid condenser 71 is further provided with a cooling water inlet 711 and a non-condensable gas outlet 712. The cooling water inlet 711 is connected to a pipeline to input cooling water, and the non-condensable gas outlet 712 is connected to a pipeline to output non-condensable gas.

[0039] The industrial waste gas treatment device also includes a wastewater treatment sub-device 8 for treating sulfide-containing wastewater. The wastewater treatment sub-device 8 is provided with an ammonia water storage tank 81, an inclined plate oil separator 82, an air flotation tank 83, and a filter 84. The sulfide in the wastewater and the ammonia water transported from the ammonia water storage tank react chemically in the inclined plate oil separator 82 to produce part of water and other compounds. After sulfur precipitation, the wastewater is purified by the air flotation tank 83 and the filter 84 and then circulated into the flash tank 2.

[0040] In this embodiment, the steam after desorption is circulated into the desorption steam condenser and is cooled by the condenser to produce 5t / h of condensed water. This condensed water contains more impurities such as tar and naphthalene, and the pH value is acidic. After the conventional water treatment measures such as neutralization with ammonia water, oil separation, flocculation, and flotation, the water is circulated into the flash tank as water replenishment for the flash tank.

[0041] The scheme of the present invention is: using steam for desorption, recovering steam heat, flashing to generate steam, and using flashed steam for desorption, thus realizing heat recovery of desorption steam.

[0042] The boiling point of benzene is 80℃. If the desorbed gas is coal gas, it is very difficult to recover the benzene. However, if it is steam desorption, the steam can be condensed and separated into oil and water to recover the benzene. In addition, with steam desorption, the waste steam after desorption contains a lot of heat, which can be recovered and reused.

[0043] The industrial waste gas treatment method of the industrial waste gas treatment device includes the following processes: After the adsorption reaches a certain adsorption rate, the adsorption tower switches to desorption regeneration. After the heating desorption state and the cooling state, the adsorption tower switches to the adsorption state again. More than three adsorption towers connected in parallel are in the adsorption state, the heating desorption state, the cooling state, and are cyclically switched for use; When the adsorption tower is in the adsorption state, the adsorption temperature is generally lower than 50°C; when the adsorption tower is in the heating desorption state, the working process is as follows: As the desorption process proceeds, the outlet temperature of the adsorption tower gradually rises to 270°C and remains constant for a period of time. At this time, the desorption gas flow rate is 5 t / h and the temperature is 280°C.

[0044] At this time, the desorption gas flow rate at the top inlet of the desorption steam condenser is 5t / h, the desorption gas temperature is 270℃, and the desorption gas pressure is 108kpa; the outlet of the desorption steam condenser is condensed water and crude benzene vapor, and the outlet temperature is about 101℃, the saturation temperature. At this time, all the water vapor is converted into liquid form, and the outlet pressure is about 106kpa. The water inlet at the bottom of the desorption steam condenser is mixed with the water replenishment of the circulating water system after the flash tank discharge is mixed with the flow rate of 675t / h, the water inlet temperature is 94.5℃, and the water outlet temperature is 99℃.

[0045] The circulating water is heated by the desorption steam condenser and then enters the flash tank. The flash tank generates 5t / h of steam, the water inlet flow is 675t / h, and the water inlet temperature is 99°C. The steam compressor is adjusted to keep the flash tank pressure at 84.6kpa and the flash temperature at 95°C, that is, the flash tank outlet steam temperature and the discharge liquid temperature are both 95°C.

[0046] The flash gas with a temperature of 95°C and a pressure of 94.6kpa enters the steam compressor. After being pressurized and heated by the compressor, the steam pressure is increased to 111kpa and the temperature is increased to 120°C. After the pressurized steam passes through the flue gas heat exchanger, the temperature rises from 120°C to 280°C and then enters another adsorption tower in a heating and desorption state for desorption. It should be noted that the heater used in this scheme is a flue gas heat exchanger.

[0047] When the adsorption tower is in a cooling state, the working process is as follows: The adsorption tower is cooled by steam after desorption. In this embodiment, water spraying is used at the bottom of the adsorption tower to reduce the steam to about 100°C and the pressure to the desorption pressure of 110kPa; that is, the adsorption tower is cooled by saturated steam, and a cooling gas with a flow rate of 1.5t / h is generated, which is merged into the steam compressor outlet pipe.

[0048] It should be noted that the cooling gas volume of the adsorption tower in the cooling state is 1.5t / h (the cooling gas is low-pressure saturated steam, and the pressure is slightly higher than the pressure in the adsorption tower, which is 110kpa). The temperature of the cooling gas increases after passing through the adsorption tower, and it flows into the steam compressor outlet pipe, and is heated by the heater together with the steam generated by the flash evaporator, and then enters the adsorption tower in the heating desorption state for desorption. Therefore, among the 5t / h flow of desorption steam at this time, 1.5t / h of the gas volume comes from the cooling gas, and only 3.5t / h of the gas volume is provided by the steam compressor.

[0049] The flash gas flow rate from the flash tank is 3.5 t / h, the temperature is 95.6℃, and the pressure is 86.5 kpa. After passing through the steam compressor, the steam is pressurized to 111 kpa, the temperature is increased to 120℃, and it is mixed with the cooling gas with a flow rate of 1.5 t / h. The mixed steam flow rate is 5 t / h. The steam temperature is increased to 280℃ through the heater (considering the heat dissipation of the pipeline, the actual heater outlet temperature is slightly higher) and then enters another adsorption tower in the heating desorption state for desorption.

[0050] As another embodiment of the present invention, after the adsorption tower is cooled by steam, the adsorption tower is further cooled by vacuuming.

[0051] In a conventional flash system, a steam compressor is used to extract the flash tank to obtain low-pressure steam, which is also one of the purposes of providing a steam compressor in the present invention.

[0052] In the present invention, by connecting the vacuum desorption pipeline with the steam compressor inlet, the steam compressor is simultaneously configured to extract the pressure inside the adsorption tower. The adsorption tower will desorb water from the adsorbent under negative pressure. Desorption is an endothermic process, which is also a cooling process of the adsorption tower.

[0053] In this embodiment, when the adsorption tower is cooled to a temperature 10-20°C higher than the steam temperature, the steam supply is stopped. Since the adsorption tower is cooled by saturated steam, a certain mass of water is adsorbed in the adsorbent. After the steam supply is stopped, the vacuum desorption pipeline valve connected to the steam compressor inlet is opened, and the steam compressor is used to evacuate the adsorption tower to a negative pressure. Under the negative pressure state, the adsorption tower will desorb water, and the desorbed water will cause the adsorption tower to continue to cool to about 50°C, thereby achieving the conditions for adsorption again.

[0054] The specific cooling process is as follows: after cooling by low-temperature steam, the temperature inside the adsorption tower in the cooling state decreases, with the top of the tower decreasing to 120°C and the bottom of the tower decreasing to 140°C. At this time, the pressure inside the adsorption tower is 108kpa, and the materials in the adsorption tower absorb water, and the water content of the materials increases to about 2.5%. The input of low-temperature steam is stopped, the steam pipeline valve is closed, and the vacuum desorption pipeline valve connected to the steam compressor inlet is opened to start negative pressure desorption of water in the adsorbent. The water desorption process is an endothermic process. As the water is desorbed, the temperature of the adsorption tower decreases, and the water vapor desorbed by negative pressure flows into the compressor inlet pipeline.

[0055] At this time, the adsorption tower and the flash tank are connected in parallel, and the water vapor generated by the negative pressure desorption of the adsorption tower and the flash steam merge at the inlet of the steam compressor.

[0056] At the beginning, the pressure in the adsorption tower is 108 kPa, the temperature is 140 °C, and the desorption steam flow rate is about 1900 m 3 / h, the tower bottom temperature rapidly drops to the saturation temperature of 102°C under the pressure and maintains this temperature for a period of time. The flow rate of desorption steam is 1.1t / h, and the steam flow rate of the flash tank connected in parallel is 3.9t / h.

[0057] The temperature at the bottom of the adsorption tower begins to gradually decrease from 102°C. At this time, the material in the tower contains about 2.2-2.5% water. The pressure in the adsorption tower also gradually decreases, and the desorption gas volume gradually decreases. When the pressure in the adsorption tower drops to the compressor inlet pressure, the desorption of water proceeds more slowly, and finally the temperature in the adsorption tower drops to 50°C.

[0058] At this time, the decompression and cooling state of the adsorption tower ends and the adsorption state begins.

[0059] In the embodiment of the present invention, the desorption steam condenser is used to recover the heat of the desorption steam, the shell side of the desorption steam condenser transmits the desorption steam, and the desorption steam is condensed into liquid after passing through the shell side of the desorption steam condenser; the tube side of the desorption steam condenser transmits circulating water, and the circulating water of the desorption steam condenser is heated and then sprayed into a flash tank to flash out low-temperature and low-pressure steam, and the other circulating water flows into the bottom of the flash tank after part of the heat is taken out by the flash steam, and is driven by a water pump to re-enter the desorption steam condenser for heating.

[0060] The desorbed steam condenses into water in the desorbed steam condenser, but the benzene and other non-condensable gases contained in it are always in a saturated state, and the outlet temperature is slightly reduced to about 101°C. After the desorbed steam is heat recovered by the desorbed steam condenser, there is still 0.1-1t / h of steam that has not been condensed. The specific amount of uncondensed steam is determined by the amount of benzene, toluene, xylene and other non-condensable gases contained in the desorbed steam. These non-condensable gases contain some hydrocarbon substances. This gas discharged after passing through the desorbed steam condenser is referred to as a benzene-containing mixed gas, which then enters the benzene liquid condenser.

[0061] The temperature of the benzene-containing mixed gas entering the benzene liquid condenser is 101°C and the pressure is 106kpa.

[0062] The cooling water of the benzene liquid condenser is the chilled water produced by the refrigeration unit, and the water temperature is 17-20℃.

[0063] The temperature of the benzene-containing mixed gas is further reduced in the benzene liquid condenser, and water and benzene are condensed into liquid phase at the same time and enter the crude benzene oil-water separation tank for static separation. The separated crude benzene enters the crude benzene tank for storage and sale; the condensed water enters the water circulation system for subsequent treatment.

[0064] There are still some non-condensable gases in the benzene liquid condenser, mainly some organic sulfides, some water vapor and trace amounts of benzene. The amount is very small and is sent to the hot air furnace for incineration. The high-temperature flue gas generated by the hot air furnace is used for the low-temperature desorption steam at the outlet of the aforementioned steam compressor.

[0065] The present invention is provided with a multi-stage condenser. In the first-stage condenser, the outlet water temperature of the flash tank of the present embodiment is 85° C.-94° C., the desorption steam contains more tar, naphthalene and benzene, and this temperature is higher than the melting point of naphthalene, which is about 80° C. Therefore, in the first-stage condenser, most of the water is condensed, and the naphthalene is still in liquid state. At this temperature, the tar and naphthalene have good fluidity and will not block the condenser. The boiling point of benzene is 80° C. Therefore, at this temperature, benzene is not condensed, but becomes non-condensable gas of the condenser and is discharged through the non-condensable gas outlet. Therefore, the non-condensable gas at the outlet of the condenser contains extremely high concentration of benzene and a small amount of water vapor, which is very beneficial to the subsequent separation of benzene liquid and water, and is convenient for the recovery of benzene.

[0066] If cold water is used in this desorption steam condenser instead of higher temperature water of 85-94℃, it will result in: ①The fluidity of tar deteriorates, causing blockage of the condenser; ② The condenser wall temperature is lower than the melting point of naphthalene (80°C), and naphthalene will crystallize on the condenser surface, causing blockage; ③Benzene will condense, and all the water and benzene will condense together, increasing the difficulty of subsequent water treatment and benzene recovery.

[0067] The present invention realizes additional benzene recovery, heat recovery, steam-water-steam recycling in the adsorption desulfurization process of coke oven gas, and realizes resource recycling in terms of material and energy.

Claims

1. An industrial waste gas treatment device, characterized in that: It includes an adsorption tower, a flash tank, a desorption steam condenser, a steam compressor, a heater, a benzene recovery sub-unit, a wastewater treatment sub-unit and an adsorbent; The adsorption tower is provided with more than 3 units, which are connected in parallel with each other. The adsorbent is installed in the tower. The adsorption tower has a first steam inlet and outlet, a second steam inlet and outlet, a cooling gas inlet and a waste gas inlet; the first steam inlet and outlet is provided at the upper part of the adsorption tower, and is connected to the flash tank pipeline; the second steam inlet and outlet is provided at the lower part of the adsorption tower, and is connected to the steam inlet pipeline of the desorption steam condenser; the second steam inlet and outlet is connected to the cooling gas inlet pipeline through a valve, and the cooling gas inlet is introduced into the low-temperature and low-pressure saturated steam; the waste gas inlet is externally connected to the waste gas pipeline, and the waste gas pipeline is introduced into the industrial waste gas to be treated; The water inlet of the flash tank is connected to the water outlet pipeline of the wastewater treatment sub-device, a circulating pump is provided on the connecting pipeline between the water outlet of the flash tank and the water inlet of the desorption steam condenser, the circulating water inlet of the flash tank and the circulating water outlet of the desorption steam condenser are connected through a pipeline, the steam compressor and the heater are provided on the connecting pipeline between the circulating water outlet of the flash tank and the first steam inlet and outlet of the adsorption tower, and the outlet of the steam compressor is connected to the inlet pipeline of the heater; The non-condensable gas outlet of the desorption steam condenser is connected to the pipeline of the benzene recovery sub-device, and the condensed water outlet of the desorption steam condenser is connected to the water inlet pipeline of the wastewater treatment sub-device.

2. The industrial waste gas treatment device according to claim 1, characterized in that The benzene recovery sub-device includes a benzene liquid condenser, an oil-water separator, and a crude benzene tank; the inlet of the benzene liquid condenser is connected to the non-condensable gas outlet pipeline of the desorption steam condenser, and the oil-water separator is provided on the connecting pipeline between the benzene liquid condenser and the crude benzene tank.

3. The industrial waste gas treatment device according to claim 1, characterized in that: The wastewater treatment sub-device includes an ammonia water storage tank, an inclined plate oil separator, an air flotation tank and a filter. The inclined plate oil separator is connected to the condensate outlet pipe of the desorption steam condenser through the ammonia water storage tank, the filter is connected to the inclined plate oil separator pipe through the air flotation tank, and the filter is externally connected to the water inlet of the flash tank.

4. The industrial waste gas treatment device according to claim 1, characterized in that: The flash tank also has a compensating steam inlet, which is externally connected to a steam pipeline, on which a regulating valve is provided; the flash tank has a wastewater outlet, which is externally connected to a drain pipe, on which a drain pump is provided.

5. The industrial waste gas treatment device according to claim 1, characterized in that , also includes a vacuum desorption pipeline, one end of which is connected to the second steam inlet and outlet of the adsorption tower, and the other end is connected to the steam compressor inlet, and the vacuum desorption pipeline is provided with a pipeline valve and a regulating valve.

6. The industrial waste gas treatment device according to claim 1, characterized in that: The desorption steam condenser is configured as a multi-stage condenser. In the first-stage condenser, the return water temperature of the flash tank is higher than the boiling point of benzene.

7. An industrial waste gas treatment method based on the industrial waste gas treatment device according to any one of claims 1 to 6, characterized in that: The following processes are included: After the adsorption reaches a certain adsorption rate, the adsorption tower switches to desorption regeneration. After the heating desorption state and the cooling state, the adsorption tower switches to the adsorption state again. At least three parallel adsorption towers are in the adsorption state, the heating desorption state, the cooling state, and are cyclically switched for use; The circulating water outlet of the flash tank is connected to the inlet pipeline of the steam compressor. The low-temperature and low-pressure saturated steam is compressed by the steam compressor and heated by the heater in turn to reach the pressure and temperature required for desorption. After entering the adsorption tower, it enters the heating desorption state; The high-temperature steam after desorption enters the desorption steam condenser through the pipeline. The desorption steam is condensed into liquid through the desorption steam condenser, enters the wastewater treatment sub-device for purification to form circulating water, and re-enters the flash tank; The desorption steam condenser transports circulating water, which is heated by steam and then sprayed into the flash tank through the circulating water outlet pipe. Part of the circulating water is flashed into low-temperature and low-pressure steam, and the other part of the circulating water flows into the bottom of the flash tank after the flash steam takes out part of the heat, and is driven by a water pump to re-enter the desorption steam condenser for heating.

8. A method for treating industrial waste gas according to claim 7, characterized in that: The following cooling steps are also included: After the adsorption tower has passed the heating and desorption state, low-temperature and low-pressure saturated steam is introduced through the cooling gas inlet and the tower enters the cooling state. The steam flows through the adsorption tower and absorbs heat in the process of flowing through the adsorption tower. At this time, the first steam inlet and outlet of the adsorption tower is connected to the outlet of the steam compressor through a pipeline, and the high-temperature steam is used as a desorption gas to flow into another adsorption tower in the heating and desorption state for desorption.

9. A method for treating industrial waste gas according to claim 7, characterized in that: The following cooling steps are also included: When the adsorption tower is cooled to the saturated steam temperature, stop introducing low-temperature and low-pressure saturated steam, open the vacuum desorption pipeline valve connected to the steam compressor inlet, and the steam compressor will pump the adsorption tower into negative pressure. Under the negative pressure state, the adsorption tower desorbs water, and the desorption of water will absorb a large amount of heat, so that the adsorption tower is further cooled to meet the conditions for re-entering the adsorption state; at this time, the adsorption tower is connected to the flash tank in parallel with the pipeline, and the water vapor generated by the negative pressure desorption of the adsorption tower and the flash steam converge in front of the steam compressor inlet.

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