Digestive system and process for high-oxygen VOCs tail gas in coking production process

Abstract

The invention discloses a digestion system and process for high-oxygen VOCs tail gas in the coking production process, and the digestion system comprises a VOCs tail gas pretreatment unit, a dry quenching recycle gas collection unit, a gas mixing and adjusting unit, a dry quenching furnace, a heat exchange boiler and a flue gas desulfurization device, the VOCs tail gas pretreatment unit and the dry quenching recycle gas collection unit are respectively communicated with the gas mixing and adjusting unit in parallel, the gas mixing and adjusting unit, the dry quenching furnace and the flue gas desulfurization device are sequentially communicated, and the heat exchange boiler and the dry quenching furnace are circularly communicated end to end. The method has the advantages of realizing stable standard reaching of environment-friendly online data, eliminating peculiar smell, purifying the field operation environment and reducing the production cost.

Description

Technical Field

[0001] The invention relates to the technical field of coking production, and in particular to a digestion system and process for high-oxygen VOCs tail gas in a coking production process. Background Art

[0002] The present invention relates to a digestion process for high-oxygen volatile organic compounds (hereinafter referred to as VOCs) tail gas in coking production, and is mainly used to solve the production and environmental protection problems of high-oxygen VOCs tail gas with strong odor. In the coking production process, desulfurization, ammonia evaporation and acid production processes will produce more VOCs tail gas. Since it contains more chemical substances such as ammonia, hydrogen sulfide, and benzene hydrocarbons, and at the same time, since it needs to be processed by alkali washing, acid washing and water washing, the moisture content in the tail gas is also relatively large. Therefore, there are production and environmental protection problems such as difficulty in processing and strong odor, which not only pollutes the environment, but also causes damage to the physical and mental health of employees.

[0003] The main function of the environmentally friendly and energy-saving process in the dry quenching coking production process is to use inert gas to extinguish the hot red coke at about 1000°C. The high-temperature flue gas after heat exchange is heat exchanged through the boiler system to produce high-temperature and high-pressure steam, which drives the steam turbine generator to generate electricity, thereby realizing the heat recovery effect of the red coke.

[0004] However, during the process of cooling down and extinguishing the red coke in the dry quenching furnace, the residual combustible substances in the red coke, such as CO and H2, will gradually evaporate and enter the inert gas of the dry quenching cycle. After a period of continuous operation, the content of combustible substances in the inert circulating gas will drop sharply. In order to ensure the safe production of the dry quenching coke oven, it is generally adopted to introduce inert N2 for dilution, or introduce air to burn the combustible gas, so as to achieve the purpose of safe operation with low content of combustible components. The former is more expensive and less used. The latter will increase the heat while burning the combustible components, increase the evaporation and generate more electricity. Therefore, dry quenching enterprises generally adopt the introduction of air with an oxygen content of about 21% to control the combustible components.

[0005] VOCs exhaust gas is a high-oxygen gas with an oxygen content generally around 20-21%, and has the properties of supporting combustion. Summary of the invention

[0006] The purpose of the present invention is to provide a digestion system and process for high-oxygen VOCs tail gas in a coking production process, so as to achieve stable compliance of environmental protection online data, eliminate odor, purify the on-site operating environment, and reduce production costs.

[0007] The above technical objectives of the present invention are achieved through the following technical solutions: A digestion system for high-oxygen VOCs tail gas in a coking production process, characterized in that it includes a VOCs tail gas pretreatment unit, a dry quenching coke circulating gas collection unit, a gas mixing and regulating unit, a dry quenching coke oven, a heat exchange boiler and a flue gas desulfurization device, the VOCs tail gas pretreatment unit and the dry quenching coke circulating gas collection unit are respectively connected in parallel with the gas mixing and regulating unit, the gas mixing and regulating unit, the dry quenching coke oven and the flue gas desulfurization device are connected in sequence, and the heat exchange boiler is connected to the dry quenching coke oven in an end-to-end circulation manner.

[0008] Preferably, the VOCs tail gas pretreatment unit comprises an alkali washing device, an acid washing device, a water washing device, a condenser, a coke filter and a conveying fan which are connected in sequence, the alkali washing device is provided with an alkali liquid spray component, the acid washing device is provided with an acid liquid atomization component, and the water washing device is provided with a two-stage countercurrent spray component.

[0009] Preferably, the CDQ circulating gas collection unit comprises an explosion-proof centrifugal fan and a circulating gas delivery pipeline which are connected in sequence, the explosion-proof centrifugal fan is equipped with a 0-50 Hz continuously adjustable frequency conversion device, and the circulating gas delivery pipeline is made of a stainless steel body lined with polytetrafluoroethylene.

[0010] Preferably, the gas mixing and regulating unit includes an electric louver regulating valve, a micro-pressure differential sensor and a gas mixing chamber, the gas mixing chamber is a Venturi mixing structure, the circulating gas delivery pipeline is connected to the main inlet of the gas mixing chamber, the side inlet of the gas mixing chamber is connected to the conveying fan, the micro-pressure differential sensor is arranged at the side inlet of the gas mixing chamber, and the electric louver regulating valve is arranged at the main inlet of the gas mixing chamber.

[0011] Preferably, a gas composition online instrument is also provided at the front end of the diffusion port of the gas mixing chamber, and the gas composition online instrument is electrically connected to the electric shutter regulating valve.

[0012] Preferably, a superheating section, an evaporation section and a coal-saving section are sequentially arranged inside the heat exchange boiler along the air inlet direction, and the outlet end of the heat exchange boiler is connected to the dry quenching coke oven through a circulating fan.

[0013] Preferably, the first outlet of the dry quenching coke oven is connected to the heat exchange boiler, and the second outlet of the dry quenching coke oven is connected to the flue gas desulfurization device through a dust extraction device.

[0014] A digestion process for high-oxygen VOCs tail gas in a coking production process, characterized in that it comprises the following steps: The CDQ circulating gas is sucked and collected by an explosion-proof centrifugal fan and enters the main inlet of the gas mixing chamber through the circulating gas delivery pipeline; After being washed with alkali, acid and water, the high-oxygen VOCs tail gas from the coking area passes through the gas condenser and coke dryer in sequence, and is then transported to the side inlet of the gas mixing chamber through a pipeline by a conveying fan; By adjusting the electric shutter regulating valve at the main entrance of the gas mixing chamber, the side entrance of the gas mixing chamber is in a slightly negative pressure state. After the two are mixed, they enter the dry quenching coke oven through the diffusion port of the gas mixing chamber; the composition of the mixed gas is detected by the gas composition online instrument; After the mixed gas is burned at a high temperature of 800-1000℃ in the CDQ oven, the waste gas generated passes through the superheating section, evaporation section and coal-saving section of the heat exchange boiler in turn for heat exchange and cooling, and then is sent to the CDQ oven by the circulating fan for recycling; The high-concentration flue gas generated after combustion in the dry coke quenching oven enters the flue gas desulfurization device for treatment after passing through the dust extraction device, and is finally discharged through the dry coke quenching chimney to achieve environmentally friendly emission standards.

[0015] Preferably, the O2 content in the mixed gas in the gas mixing chamber is not higher than 3%, the H2 content is 1-3%, and the CO content is 4-12%.

[0016] Preferably, the particulate matter in the flue gas treated by the flue gas desulfurization device is 1 to 5 mg / m 3 , SO2 content is 10~25mg / m 3 .

[0017] In summary, the beneficial effects of the present invention are as follows: the high-oxygen VOCs tail gas from the coking area replaces the air required for dry coke quenching production and is introduced into the dry quenching furnace, and is environmentally friendly consumed by high-temperature treatment. In this treatment method, on the one hand, the high-oxygen and odorous VOCs tail gas is decomposed by high-temperature combustion in the dry quenching furnace, purified by the desulfurization system and discharged from the dry quenching chimney, which completely solves the odor problem of low-altitude emission of VOCs gas, improves the on-site environment, and has significant environmental benefits; on the other hand, chemical substances such as benzene hydrocarbons in the VOCs tail gas will increase the heat of the flue gas in the dry quenching furnace when burned in the dry quenching furnace, which is beneficial to increasing the steam production of the boiler and creating certain economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the system structure of the present invention. DETAILED DESCRIPTION

[0019] The specific implementation manner of the present invention is further described below in conjunction with the accompanying drawings, and this embodiment does not constitute a limitation of the present invention.

[0020] like Figure 1The digestion system of high-oxygen VOCs tail gas in a coking production process shown in the figure includes a VOCs tail gas pretreatment unit, a dry quenching circulating gas collection unit, a gas mixing and regulating unit, a dry quenching coke oven 10, a heat exchange boiler 11 and a flue gas desulfurization device 13. The VOCs tail gas pretreatment unit and the dry quenching circulating gas collection unit are respectively connected in parallel with the gas mixing and regulating unit, the gas mixing and regulating unit, the dry quenching coke oven 10 and the flue gas desulfurization device 13 are connected in sequence, and the heat exchange boiler 11 is connected to the dry quenching coke oven 10 in an end-to-end circulation manner.

[0021] The VOCs tail gas pretreatment unit includes an alkali washing device 1, an acid washing device 2, a water washing device 3, a condenser 4, a coke filter 5 and a conveying fan 6 which are connected in sequence. The alkali washing device 1 is equipped with an alkali liquid spray component, the acid washing device 2 is equipped with an acid liquid atomization component, and the water washing device 3 is equipped with a two-stage countercurrent spray component.

[0022] The CDQ circulating gas collection unit comprises an explosion-proof centrifugal fan 7 and a circulating gas delivery pipeline 8 which are connected in sequence. The explosion-proof centrifugal fan 7 is equipped with a 0-50Hz continuously adjustable frequency conversion device. The circulating gas delivery pipeline 8 is made of a stainless steel body lined with polytetrafluoroethylene.

[0023] The gas mixing and regulating unit includes an electric shutter regulating valve, a micro-pressure differential sensor and a gas mixing chamber 9. The gas mixing chamber 9 is a Venturi mixing structure. The circulating gas delivery pipeline 8 is connected to the main inlet of the gas mixing chamber 9. The side inlet of the gas mixing chamber 9 is connected to the conveying fan 6. The micro-pressure differential sensor is arranged at the side inlet of the gas mixing chamber 9, and the electric shutter regulating valve is arranged at the main inlet of the gas mixing chamber 9.

[0024] A gas composition online instrument is also provided at the front end of the diffusion port of the gas mixing chamber 9, and the gas composition online instrument is electrically connected to the electric shutter regulating valve.

[0025] A superheating section, an evaporation section and a coal-saving section are sequentially arranged inside the heat exchange boiler 11 along the air intake direction, and the outlet end of the heat exchange boiler 11 is connected to the dry quenching coke oven 10 through a circulating fan.

[0026] The first outlet of the dry quenching coke oven 10 is connected to the heat exchange boiler 11 , and the second outlet of the dry quenching coke oven 10 is connected to the flue gas desulfurization device 13 through the dust extraction device 12 .

[0027] A digestion process for high-oxygen VOCs tail gas in a coking production process comprises the following steps: The CDQ circulating gas is sucked and collected by the explosion-proof centrifugal fan 7 and enters the main inlet of the gas mixing chamber 9 through the circulating gas delivery pipeline 8.

[0028] After alkali washing, acid washing and water washing, the high-oxygen VOCs tail gas in the coking area passes through the gas condenser 4 and the coke dryer in sequence, and is transported to the side inlet of the gas mixing chamber 9 through the pipeline via the conveying fan 6.

[0029] By adjusting the electric shutter regulating valve at the main entrance of the gas mixing chamber 9, the side entrance of the gas mixing chamber 9 is placed in a slightly negative pressure state. After the two are mixed, they enter the dry quenching coke oven 10 through the diffusion port of the gas mixing chamber 9; the composition of the mixed gas is detected by the gas composition online instrument. The O2 content in the mixed gas is not higher than 3%, the H2 content is 1-3%, and the CO content is 4-12%.

[0030] After the mixed gas is burned at a high temperature of 800-1000°C in the dry quenching coke oven 10, the exhaust gas generated passes through the superheating section, evaporation section and coal-saving section of the heat exchange boiler 11 for heat exchange and cooling, and is then sent to the dry quenching coke oven 10 by the circulating fan for recycling.

[0031] The high-concentration flue gas generated after combustion in the dry quenching coke oven 10 passes through the dust extraction device 12 and enters the flue gas desulfurization device 13 for treatment. The particulate matter in the flue gas is 1-5 mg / m 3 , SO2 content is 10~25mg / m 3 , and ultimately achieve environmentally friendly emissions through the dry coke quenching chimney.

[0032] The present invention introduces high-oxygen VOCs tail gas from the coking area into the dry quenching furnace instead of the air required for dry quenching production, and disposes it in an environmentally friendly manner by high-temperature treatment. This treatment method, on the one hand, the high-oxygen and odorous VOCs tail gas is decomposed by high-temperature combustion in the dry quenching furnace, purified by the desulfurization system and discharged from the dry quenching chimney, which completely solves the odor problem of low-altitude emission of VOCs gas, improves the on-site environment, and has significant environmental benefits; on the other hand, chemical substances such as benzene hydrocarbons in the VOCs tail gas will increase the heat of the flue gas in the dry quenching furnace when burned in the dry quenching furnace, which is beneficial to increasing the steam production of the boiler and creating certain economic benefits.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent substitutions should also be deemed to fall within the protection scope of the technical solution of the present invention.

Claims

1. A digestion system for high-oxygen VOCs tail gas in a coking production process, characterized in that: It includes a VOCs tail gas pretreatment unit, a dry quenching coke circulating gas collection unit, a gas mixing and regulating unit, a dry quenching coke oven, a heat exchange boiler and a flue gas desulfurization device. The VOCs tail gas pretreatment unit and the dry quenching coke circulating gas collection unit are respectively connected in parallel with the gas mixing and regulating unit, the gas mixing and regulating unit, the dry quenching coke oven and the flue gas desulfurization device are connected in sequence, and the heat exchange boiler is connected to the dry quenching coke oven in an end-to-end circulation manner.

2. The digestion system of high-oxygen VOCs tail gas in a coking production process according to claim 1, characterized in that: The VOCs tail gas pretreatment unit includes an alkali washing device, an acid washing device, a water washing device, a condenser, a coke filter and a conveying fan which are connected in sequence. The alkali washing device is equipped with an alkali liquid spray component, the acid washing device is equipped with an acid liquid atomization component, and the water washing device is equipped with a two-stage countercurrent spray component.

3. The digestion system of high-oxygen VOCs tail gas in a coking production process according to claim 2, characterized in that: The CDQ circulating gas collection unit comprises an explosion-proof centrifugal fan and a circulating gas delivery pipeline which are connected in sequence. The explosion-proof centrifugal fan is equipped with a 0-50Hz continuous frequency conversion device. The circulating gas delivery pipeline is made of a stainless steel body lined with polytetrafluoroethylene.

4. The digestion system of high-oxygen VOCs tail gas in a coking production process according to claim 3, characterized in that: The gas mixing and regulating unit includes an electric louver regulating valve, a micro-pressure differential sensor and a gas mixing chamber. The gas mixing chamber is a Venturi mixing structure. The circulating gas delivery pipeline is connected to the main inlet of the gas mixing chamber. The side inlet of the gas mixing chamber is connected to the conveying fan. The micro-pressure differential sensor is arranged at the side inlet of the gas mixing chamber, and the electric louver regulating valve is arranged at the main inlet of the gas mixing chamber.

5. The digestion system of high-oxygen VOCs tail gas in a coking production process according to claim 4, characterized in that: A gas composition online instrument is also provided at the front end of the diffusion port of the gas mixing chamber, and the gas composition online instrument is electrically connected to the electric shutter regulating valve.

6. The digestion system of high-oxygen VOCs tail gas in a coking production process according to claim 1, characterized in that: The heat exchange boiler is provided with a superheating section, an evaporation section and a coal-saving section in sequence along the air inlet direction, and the outlet end of the heat exchange boiler is connected with the dry quenching coke oven through a circulating fan.

7. The digestion system of high-oxygen VOCs tail gas in a coking production process according to claim 6, characterized in that: The first outlet of the dry quenching coke oven is connected to the heat exchange boiler, and the second outlet of the dry quenching coke oven is connected to the flue gas desulfurization device through a dust extraction device.

8. A digestion process for high-oxygen VOCs tail gas in a coking production process, characterized by: The steps include: The CDQ circulating gas is sucked and collected by an explosion-proof centrifugal fan and enters the main inlet of the gas mixing chamber through the circulating gas delivery pipeline; After being washed with alkali, acid and water, the high-oxygen VOCs tail gas from the coking area passes through the gas condenser and coke dryer in sequence, and is then transported to the side inlet of the gas mixing chamber through a pipeline by a conveying fan; By adjusting the electric shutter regulating valve at the main entrance of the gas mixing chamber, the side entrance of the gas mixing chamber is in a slightly negative pressure state. After the two are mixed, they enter the dry quenching coke oven through the diffusion port of the gas mixing chamber; the composition of the mixed gas is detected by the gas composition online instrument; After the mixed gas is burned at a high temperature of 800-1000℃ in the CDQ oven, the waste gas generated passes through the superheating section, evaporation section and coal-saving section of the heat exchange boiler in turn for heat exchange and cooling, and then is sent to the CDQ oven by the circulating fan for recycling; The high-concentration flue gas generated after combustion in the dry coke quenching oven enters the flue gas desulfurization device for treatment after passing through the dust extraction device, and is finally discharged through the dry coke quenching chimney to achieve environmentally friendly emission standards.

9. The digestion process of high-oxygen VOCs tail gas in a coking production process according to claim 8, characterized in that: The O2 content in the mixed gas in the gas mixing chamber is not higher than 3%, the H2 content is 1-3%, and the CO content is 4-12%.

10. The digestion process of high-oxygen VOCs tail gas in a coking production process according to claim 8, characterized in that: The particulate matter in the flue gas treated by the flue gas desulfurization device is 1-5 mg / m 3 , SO2 content is 10~25mg / m 3 .

Images