Treatment system for coking tail gas containing volatile organic compounds and coking system

Abstract

The utility model provides a treatment system for coking tail gas containing volatile organic compounds and a coking system. A coke oven gas negative pressure system of the treatment system is used for carrying out negative pressure recovery on diffused tail gas containing volatile organic compounds from a cold drum section and a benzene elution section of coking equipment; and the recovered tail gas is subjected to pressure regulation through a coke oven gas negative pressure system and then is conveyed to an air blower, so that the fugitive emission of volatile organic compounds in the diffused tail gas is prevented. The washing system is used for washing the tail gas containing volatile organic compounds from the ammonium sulfate section, the desulfurization and sulfur recovery section and the tar tank field section; the adsorber is used for adsorbing the tail gas washed by the washing system; the water removal separator is used for removing water from the tail gas treated by the adsorber; the air blower is used for pressurizing tail gas from the coke oven gas negative pressure system and the water removal separator; and the flue gas return and distribution fan distributes the pressurized tail gas and the flue gas of the coke oven to a combustion chamber of the coke oven for combustion, so that the total energy consumption is correspondingly reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to coking tail gas treatment technical field especially relates to a kind of coking volatile organic compounds tail gas treatment system and coking system. BACKGROUND

[0002] Coking is an important coal conversion mode, due to its pollution, high energy consumption, has become one of the main sources of air pollution in China. Volatile organic compounds (VOCs, such as benzene, toluene, polycyclic aromatic hydrocarbons, n-hexane) produced in the coking process are toxic and harmful pollutants, which mainly harm the environment: first, it is the precursor of fine particulate matter (PM2.5) and ozone (O3) ;Second, it is easy to react with O3 to generate secondary organic aerosols (SOA), and SOA is the precursor of haze;Third, it is easy to react with NO x and SO2 to generate photochemical smog;Fourth, it absorbs infrared radiation, aggravating global warming.

[0003] With the rapid development of industrialization and urbanization, photochemical smog and haze-related air pollution characterized by O3 and PM2.5 have become one of the environmental problems that countries focus on. As the main precursor of O3 and SOA, VOCs have a major impact on atmospheric chemistry, regional environment and earth climate. VOCs can be converted to O3 and SOA by reacting with NOX under weather conditions such as high temperature, low humidity, strong radiation and low wind speed.

[0004] The health effects of VOCs on the human body include both indirect and direct effects. Direct effects mainly manifest when the human body directly contacts toxic VOCs, and the heart, lungs, liver and nervous system of the human body are greatly affected by these substances, causing widespread acute (sensory, nervous system damage) and chronic health (asthma or cancer, etc.) effects, which pose a great threat to human health. Indirect effects mainly include the formation of haze caused by the photochemical effect of VOCs, and fine particulate matter in the haze can enter the human lung, causing respiratory system disease, which indirectly causes great damage to human health. INVENTION CONTENTS

[0005] The purpose of the embodiment of the utility model is to provide a coking volatile organic compounds tail gas treatment system and coking system to solve the problem of environmental pollution and harm to human health caused by volatile organic compounds produced in the coking process.

[0006] The embodiment of the utility model adopts the following technical scheme: a coking volatile organic compounds tail gas treatment system applied to coking equipment, comprising:

[0007] A coke oven gas negative pressure system connected with the coking device, for recovering volatile organic matter-containing emission tail gas from the cold drum section and the benzene elution section of the coking device under negative pressure;

[0008] A washing system connected with the coking device, for washing volatile organic matter-containing tail gas from the ammonium sulfate section, the desulfurization and sulfur recovery section, and the tar tank section;

[0009] An adsorber connected with the washing system, for adsorbing the tail gas washed by the washing system;

[0010] A water separation device connected with the adsorber, for removing water from the tail gas treated by the adsorber;

[0011] A blower connected with the coke oven gas negative pressure system and the water separation device respectively, to pressurize the tail gas from the coke oven gas negative pressure system and the water separation device;

[0012] A flue gas distribution blower connected with the blower and the coke oven flue gas main pipe, to distribute the pressurized tail gas and coke oven flue gas to the coke oven combustion chamber for combustion.

[0013] In some embodiments, the washing system comprises:

[0014] An oil washing tower connected with the coking device, for washing volatile organic matter-containing tail gas from the ammonium sulfate section, the desulfurization and sulfur recovery section, and the tar tank section, to remove at least part of the tar, naphthalene and benzene in the tail gas;

[0015] An acid washing tower connected with the oil washing tower, for acid washing the tail gas washed by the oil washing tower, to remove ammonia gas in the tail gas;

[0016] An alkali washing tower connected with the acid washing tower, for alkali washing the tail gas washed by the acid washing tower, to remove hydrogen sulfide and hydrogen cyanide in the tail gas;

[0017] A water washing tower connected with the alkali washing tower, for water washing the tail gas washed by the alkali washing tower, to remove residual alkali liquor in the tail gas.

[0018] In some embodiments, the oil washing tower is further connected with a clarifier, so that the saturated washing liquid in the oil washing tower can be discharged to the clarifier.

[0019] In some embodiments, a secondary demister is arranged at the top of the acid washing tower, and a gas collecting pipe is arranged between the top of the acid washing tower and the alkali washing tower, so that the tail gas demisted by the secondary demister enters the alkali washing tower through the gas collecting pipe.

[0020] In some embodiments, the processing system further comprises an oxygen content detector arranged on an air inlet pipeline close to an air inlet of the coke oven gas negative pressure system, and a switch valve and a diffusion valve are further arranged on the air inlet pipeline.

[0021] In some embodiments, granular activated carbon is arranged in the adsorber, and the activated carbon forms a columnar adsorption structure.

[0022] In some embodiments, the processing system further comprises a coke oven exhaust disc connected with the flue gas back blower and the coke combustion chamber respectively, the flue gas back blower sends the coke flue gas and the treated tail gas to the coke oven exhaust disc after pressurization, and the coke flue gas and the treated tail gas are sent to the coke combustion chamber after mixing in the coke oven exhaust disc.

[0023] The embodiment of the application further provides a coking system comprising a coking device and a processing system for coking tail gas containing volatile organic compounds as described in any of the above embodiments.

[0024] The embodiment of the application has the following beneficial effects:

[0025] The diffusion tail gas of the cold drum section and the benzene elution section of the coking device is recovered respectively, and the recovered tail gas is sent to the blower after pressure adjustment by the coke oven gas negative pressure system, so that unorganized emission of volatile organic compounds in the diffusion tail gas is prevented, the atmospheric environment is improved, the operation cost is low, the process is simple, and there is no secondary pollution. The tail gas of the ammonium sulfate section, the desulfurization and sulfur recovery section, and the tar tank section is treated by a series of washing, and is sent to the coke combustion chamber as fuel together with the treated diffusion tail gas of the cold drum section and the benzene elution section for combustion, so that additional heat is provided for the coking device, and the total energy consumption is correspondingly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the application or the related art, the following will briefly introduce the drawings needed to be used in the embodiment or related art description. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0027] Figure 1 The structure diagram of the processing system for coking tail gas containing volatile organic compounds.

[0028] Reference numerals: 1, coke oven gas negative pressure system; 2, cold drum section; 3, benzene washing section; 4, washing system; 401, washing oil washing tower; 402, acid washing tower; 403, alkali washing tower; 404, water washing tower; 5, ammonium sulfate section; 6, desulfurization and sulfur recovery section; 7, tar tank area section; 8, adsorber; 9, water removal separator 9; 10, air blower; 11, flue gas distribution blower; 12, coke oven flue gas main; 13, coke oven combustion chamber. DETAILED DESCRIPTION

[0029] Various aspects and features of the present application are described herein below with reference to the accompanying drawings.

[0030] It is to be understood that various alterations and modifications can be made to the embodiments described herein. Therefore, the above description should not be taken as limiting, but merely as exemplification of the embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the application.

[0031] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and, together with the general description of the application given above, and the detailed description of the embodiments given below, serve to explain the principles of the present application.

[0032] These and other characteristics of the present application will become apparent from the following description of the preferred forms given, by way of non-limiting example only, with reference to the attached drawings.

[0033] It is also to be understood that, although a certain number of specific language is used herein, this does not preclude the use of other terms and phrases unless contextually inconsistent.

[0034] The above and other aspects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:

[0035] Specific embodiments of the present application are described herein below, with reference to the accompanying drawings; however, it should be understood that the disclosed embodiments are merely examples of the present application, which can be implemented in numerous ways. Well-known and / or redundant functions and structures are not described in detail to avoid obscuring the present application unnecessarily. Therefore, specific structural and functional details disclosed herein are not intended to limit the present application, but merely as a representative basis for the claims and for teaching a person skilled in the art to employ the present application in substantially any appropriate detailed structure.

[0036] The present specification can use the phrases "in one embodiment," "in another embodiment," "in yet another embodiment," or "in other embodiments," which can refer to one or more embodiments according to the present application.

[0037] This application provides a treatment system for coking tail gas containing volatile organic compounds. This treatment system can be applied to coking equipment, which can be a coking furnace.

[0038] like Figure 1 As shown, the treatment system includes a coke oven gas negative pressure system 1, a washing system 4, an adsorber 8, a water separator 9, a blower 10, and a flue gas return distribution fan 11.

[0039] The coke oven gas negative pressure system 1 is connected to the coking equipment and is used to recover volatile organic compound (VOC)-containing exhaust gases from the cooling drum section 2 and the benzene washing and removal section 3. The VOC exhaust gases from the cooling drum section and the benzene washing and removal section are collected directly in a closed system, and then enter the coke oven gas negative pressure system 1. An oxygen content detector can be added to the inlet pipe before the VOC exhaust gases enter the coke oven gas negative pressure system 1 to monitor the oxygen content in the VOC exhaust gases entering the system in real time. If the oxygen content exceeds the standard, the VOC exhaust gases entering the coke oven gas negative pressure system 1 are immediately cut off, and the emergency vent valve opens to release the VOC exhaust gases, ensuring that only qualified VOC exhaust gases enter the coke oven gas negative pressure system 1 without affecting its normal operation. Switch valves and vent valves can be installed on the inlet pipe, which can be opened and closed as needed. Using the negative pressure before the blower 10 of the gas purification unit as power, the exhaust gases from the cold blowing section and the benzene washing section 3 are respectively recovered to the exhaust gas recovery branch system. The branch system is collected into the exhaust gas main pipe. After pressure regulation, the exhaust gas main pipe is connected to the gas main pipe before the blower 10. This eliminates the fugitive emission of VOCs exhaust gas, has low operating costs, simple process, and no secondary pollution. It can also recover benzene, ammonia and other substances in the exhaust gas through the gas purification system, realizing the transformation of exhaust gas into a valuable resource, improving the on-site atmospheric environment, and correspondingly reducing the total energy consumption of the system.

[0040] The washing system 4 is connected to the coking equipment and is used to wash the tail gas containing volatile organic compounds from the ammonium sulfate section 5, the desulfurization and sulfur recovery section 6, and the tar tank area section 7. The washing system 4 includes an oil washing tower 401, an acid washing tower 402, an alkaline washing tower 403, and a water washing tower 404. The oil washing tower 401 is connected to the coking equipment and is used to wash the tail gas containing volatile organic compounds from the ammonium sulfate section 5, the desulfurization and sulfur recovery section 6, and the tar tank area section 7 to remove at least some of the tar, naphthalene, and benzene from the tail gas. The acid washing tower 402 is connected to the oil washing tower 401 and is used to perform acid washing on the tail gas after washing in the oil washing tower 401 to remove ammonia from the tail gas. The alkaline washing tower 403 is connected to the acid washing tower 402 and is used to perform alkaline washing on the tail gas after washing in the acid washing tower 402 to remove hydrogen sulfide and hydrogen cyanide from the tail gas. Water washing tower 404 is connected to alkali washing tower 403 and is used to wash the tail gas after it has been washed by alkali washing tower 403 to remove residual alkali solution from the tail gas.

[0041] The adsorber 8 is connected with the washing system 4, and is used for adsorbing the tail gas after being washed by the washing system 4. The water separator 9 is connected with the adsorber 8, and is used for removing water from the tail gas after being treated by the adsorber 8.

[0042] After the tail gas of the ammonium sulfate section 5, the desulfurization and sulfur recovery section 6 and the tar tank section 7 is collected, the tail gas firstly enters the washing oil washing tower 401. The washing oil tower uses new washing oil to wash the VOCs tail gas. The main purpose in the washing oil washing tower 401 is to remove most of the organic matters such as tar, naphthalene and benzene in the VOCs tail gas. The washing oil washing tower 401 can also be connected with the clarifier, so that the saturated washing liquid in the washing oil washing tower 401 can be discharged to the clarifier. Specifically, after the washing oil washing tower 401 works for a period of time, the saturated washing liquid in the washing oil washing tower 401 is discharged to the clarifier. After the VOCs tail gas is discharged from the washing oil tower, the VOCs tail gas enters the pickling tower 402 for washing. In the pickling tower 402, NH3 in the VOCs tail gas is washed by the absorption liquid and reacts with H2SO4 in the absorption liquid to generate (NH4)2SO4. 4， The reaction equation is: H2SO4+2NH3=(NH4)2SO4. The absorption liquid in the pickling tower 402 is discharged to the mother liquor tank of the ammonium sulfate section 5.

[0043] A secondary demister is arranged at the top of the pickling tower 402. A gas collecting pipeline is arranged between the top of the pickling tower 402 and the caustic washing tower 403. The tail gas after being demisted by the secondary demister enters the caustic washing tower 403 through the gas collecting pipeline. Specifically, after the VOCs tail gas is discharged from the pickling tower 402, the VOCs tail gas enters the caustic washing tower 403 through the secondary demister at the top of the pickling tower 402 and the gas collecting pipeline.

[0044] NaOH solution is used in the caustic washing tower 403 to absorb H2S and HCN in the VOCs tail gas. The reaction equation is: 2NaOH+H2S=Na2S+2H2O, NaOH+HCN=NaCN+H2O. The absorption liquid in the caustic washing tower 403 is discharged to the mechanical clarifier. The VOCs tail gas discharged from the caustic washing tower 403 enters the adsorption and desorption device to adsorb the VOCs tail gas.

[0045] Granular activated carbon is arranged in the adsorber 8, and the activated carbon forms a columnar adsorption structure. That is, the columnar granular activated carbon is used in the adsorber 8 to adsorb the VOCs tail gas. The VOCs tail gas after being treated by the adsorption and desorption device enters the water separator 9 to remove water. After the VOCs tail gas is removed of water, the VOCs tail gas is pressurized by the fan of the ammonium sulfate section 5, the desulfurization and sulfur recovery section 6 and the tar tank section 7, and is sent to the flue gas distribution fan 11 through the outer pipe to be mixed with part of the flue gas.

[0046] The air blower 10 is connected with the coke oven gas negative pressure system 1 and the water separator 9 respectively to pressurize the tail gas from the coke oven gas negative pressure system 1 and the water separator 9. The flue gas distribution blower 11 is connected with the air blower 10 and the coke oven flue gas main pipe 12 to distribute the pressurized tail gas and the coke oven flue gas to the coke oven combustion chamber 13 for combustion.

[0047] The processing system further comprises a coke oven waste gas tray connected with the flue gas distribution blower 11 and the coke oven combustion chamber 13 respectively, the flue gas distribution blower 11 pressurizes the coke oven flue gas and the processed tail gas and then sends them to the coke oven waste gas tray, mixes them in the coke oven waste gas tray and then sends them to the coke oven combustion chamber 13. After being pressurized by the flue gas distribution blower 11, the coke oven flue gas is sent to the coke oven waste gas tray and then is distributed as air to the coke oven combustion chamber 13 to provide additional fuel. During the combustion process, the combustible components such as hydrocarbons in the VOCs tail gas participate in the combustion reaction together with the traditional fuel such as coke oven gas in the coke oven to release heat, and the calorific value of the coke oven gas is increased from 17527 KJ / m 3 before the VOCs tail gas is introduced to 18456 KJ / m 3 , which provides additional heat for the coke oven and ensures the smooth progress of the coking process.

[0048] The coking VOCs tail gas is effectively treated by the method of entering the negative pressure system-oil washing, acid washing, alkali washing, activated carbon adsorption, water separation, and then entering the coke oven for air distribution and combustion. After the coking VOCs tail gas is removed, the total VOCs amount is ≤70 mg / m 3 , the non-methane total hydrocarbon emission concentration is ≤50 mg / m 3 , and the nitrogen oxide emission concentration is ≤150 mg / m 3 . By treating the VOCs tail gas in coking, the emission of toxic and harmful gases such as benzene, toluene, xylene, etc. in the VOCs tail gas can be effectively reduced, the air pollution can be reduced, the health of the surrounding residents and the balance and stability of the ecological system can be protected, the energy can be saved, the consumption of traditional energy such as coke oven gas can be reduced, and the coke oven gas consumption per ton of coke is reduced from 198 m 3 before the VOCs tail gas is introduced to 188 m 3 , which is equivalent to 1.8 yuan / ton of coke in electricity cost. The coking VOCs tail gas environmental protection and energy saving treatment method is beneficial to recycle the VOCs tail gas which pollutes the environment to the coke oven combustion chamber 13 as fuel, which not only solves the environmental pollution problem but also brings objective economic benefits and meets the requirements of circular economy development.

[0049] The embodiment of the present application further provides a coking system comprising a coking device and a coking VOCs tail gas processing system as described in any of the above embodiments.

[0050] The diffused tail gas of the coke drum section and the benzene elution section 3 of the coking equipment is recovered respectively, and then the recovered tail gas is conveyed to the air blower 10 after pressure adjustment by the coke oven gas negative pressure system 1, so that unorganized emission of volatile organic compounds in the diffused tail gas is prevented, the atmospheric environment is improved, the operation cost is low, the process is simple, and there is no secondary pollution. The tail gas of the ammonium sulfate section 5, the desulfurization and sulfur recovery section 6 and the tar tank area section 7 is washed by a series of washing processes, and then is conveyed to the coke oven combustion chamber 13 as fuel together with the diffused tail gas of the coke drum section and the benzene elution section 3 after treatment, so as to be combusted, thereby providing additional heat for the coking equipment, and correspondingly reducing the total energy consumption.

[0051] The above describes in detail multiple embodiments of the present application, but the present application is not limited to these specific embodiments. Based on the concept of the present application, those skilled in the art can make various modified embodiments, and these modifications shall fall within the scope of the present application.

Claims

1. A treatment system for coking tail gas containing volatile organic compounds, characterized in that, Used in coking equipment, including: A coke oven gas negative pressure system, which is connected to the coking equipment, is used to perform negative pressure recovery of the exhaust gas containing volatile organic compounds from the cooling drum section and the benzene washing section of the coking equipment. A washing system, connected to the coking equipment, is used to wash the tail gas containing volatile organic compounds from the ammonium sulfate section, the desulfurization and sulfur recovery section, and the tar tank area section. An adsorber, which is connected to the washing system, is used to adsorb the exhaust gas after it has been washed by the washing system. A water separator, connected to the adsorber, is used to remove moisture from the exhaust gas after it has been treated by the adsorber. A blower is connected to the coke oven gas negative pressure system and the water separator respectively to pressurize the tail gas from the coke oven gas negative pressure system and the water separator; A flue gas return fan is connected to the blower and the coke oven flue gas main to distribute the pressurized tail gas and coke oven flue gas to the coke oven combustion chamber for combustion.

2. The coking tail gas treatment system containing volatile organic compounds according to claim 1, characterized in that, The washing system includes: An oil washing tower, connected to the coking equipment, is used to wash the tail gas containing volatile organic compounds from the ammonium sulfate section, the desulfurization and sulfur recovery section, and the tar tank area section, in order to remove at least part of the tar, naphthalene, and benzene from the tail gas. A pickling tower, which is connected to the washing oil scrubbing tower, is used to perform pickling treatment on the tail gas after it has been washed by the washing oil scrubbing tower, so as to remove ammonia from the tail gas. An alkaline scrubbing tower, connected to the acid scrubbing tower, is used to perform alkaline scrubbing on the tail gas after it has been scrubbed by the acid scrubbing tower, so as to remove hydrogen sulfide and hydrogen cyanide from the tail gas. A water washing tower, connected to the alkali washing tower, is used to wash the tail gas after it has been washed by the alkali washing tower, thereby removing residual alkali from the tail gas.

3. The coking tail gas treatment system containing volatile organic compounds according to claim 2, characterized in that, The washing tower is also connected to a clarification tank so that the saturated washing liquid in the washing tower can be discharged into the clarification tank.

4. The coking tail gas treatment system containing volatile organic compounds according to claim 2, characterized in that, The top of the acid washing tower is equipped with a two-stage demister, and a gas collection pipe is provided between the top of the acid washing tower and the alkaline washing tower. The exhaust gas after being demisted by the two-stage demister enters the alkaline washing tower through the gas collection pipe.

5. The coking tail gas treatment system containing volatile organic compounds according to claim 1, characterized in that, The processing system also includes an oxygen content detector, which is installed on the air inlet pipe near the air inlet of the coke oven gas negative pressure system. The air inlet pipe is also equipped with a switch valve and a vent valve.

6. The coking tail gas treatment system containing volatile organic compounds according to claim 1, characterized in that, The adsorber contains granular activated carbon, which forms a columnar adsorption structure.

7. The coking tail gas treatment system containing volatile organic compounds according to claim 1, characterized in that, The treatment system also includes a coke oven exhaust gas pan, which is connected to the flue gas return fan and the coke oven combustion chamber respectively. The flue gas return fan pressurizes the coke oven flue gas and the treated tail gas and then delivers them to the coke oven exhaust gas pan. After being mixed by the coke oven exhaust gas pan, the gas is then delivered to the coke oven combustion chamber.

8. A coking system, characterized in that, It includes coking equipment and a treatment system for coking exhaust gas containing volatile organic compounds as described in any one of claims 1 to 7.

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