CN117065502A - Environment-friendly coal chemical VOC recycling method and system - Google Patents
Environment-friendly coal chemical VOC recycling method and system Download PDFInfo
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- CN117065502A CN117065502A CN202310853051.8A CN202310853051A CN117065502A CN 117065502 A CN117065502 A CN 117065502A CN 202310853051 A CN202310853051 A CN 202310853051A CN 117065502 A CN117065502 A CN 117065502A
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- 238000000034 method Methods 0.000 title claims abstract description 47
- 239000000126 substance Substances 0.000 title claims abstract description 39
- 238000004064 recycling Methods 0.000 title claims abstract description 34
- 239000003245 coal Substances 0.000 title claims abstract description 31
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 168
- 239000007789 gas Substances 0.000 claims abstract description 111
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 55
- 239000002912 waste gas Substances 0.000 claims abstract description 53
- 238000011084 recovery Methods 0.000 claims abstract description 32
- 238000010521 absorption reaction Methods 0.000 claims abstract description 19
- 238000009833 condensation Methods 0.000 claims abstract description 19
- 230000005494 condensation Effects 0.000 claims abstract description 19
- 230000008569 process Effects 0.000 claims abstract description 19
- 238000007710 freezing Methods 0.000 claims abstract description 15
- 230000008014 freezing Effects 0.000 claims abstract description 15
- 238000007599 discharging Methods 0.000 claims abstract description 14
- 230000001502 supplementing effect Effects 0.000 claims abstract description 13
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 10
- 239000003546 flue gas Substances 0.000 claims abstract description 10
- 238000010344 co-firing Methods 0.000 claims abstract description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 55
- 229910052757 nitrogen Inorganic materials 0.000 claims description 28
- 238000005406 washing Methods 0.000 claims description 27
- 239000000047 product Substances 0.000 claims description 24
- 230000000087 stabilizing effect Effects 0.000 claims description 23
- 239000002351 wastewater Substances 0.000 claims description 15
- 239000012535 impurity Substances 0.000 claims description 12
- 238000002485 combustion reaction Methods 0.000 claims description 11
- 238000003860 storage Methods 0.000 claims description 11
- 230000001105 regulatory effect Effects 0.000 claims description 9
- 230000007613 environmental effect Effects 0.000 claims description 7
- 239000013589 supplement Substances 0.000 claims description 6
- 238000012544 monitoring process Methods 0.000 claims description 5
- 230000009467 reduction Effects 0.000 claims description 5
- 230000001276 controlling effect Effects 0.000 claims description 4
- 238000004458 analytical method Methods 0.000 claims description 3
- 230000000630 rising effect Effects 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 3
- 238000011068 loading method Methods 0.000 abstract description 7
- 238000001311 chemical methods and process Methods 0.000 abstract description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 2
- 239000012855 volatile organic compound Substances 0.000 description 10
- 230000003647 oxidation Effects 0.000 description 8
- 238000007254 oxidation reaction Methods 0.000 description 8
- 239000007788 liquid Substances 0.000 description 7
- 238000002156 mixing Methods 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000010790 dilution Methods 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000002360 explosive Substances 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000711 cancerogenic effect Effects 0.000 description 1
- 231100000315 carcinogenic Toxicity 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000004200 deflagration Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 230000009323 psychological health Effects 0.000 description 1
- 239000003507 refrigerant Substances 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/002—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by condensation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1406—Multiple stage absorption
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1487—Removing organic compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/70—Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
- B01D2257/704—Solvents not covered by groups B01D2257/702 - B01D2257/7027
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/70—Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
- B01D2257/708—Volatile organic compounds V.O.C.'s
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Treating Waste Gases (AREA)
Abstract
The application provides an environment-friendly coal chemical VOC recycling method and system, wherein the recycling method is as follows; introducing tail gas in the coal chemical industry into a tank area tail gas collecting system, judging whether an initial pressure value in a tank is at a normal threshold value, and sending the tail gas after freezing and recycling in the middle tank area to a newly-added tail gas water scrubber for continuously supplementing desalted water to circularly absorb methanol; identifying whether the boiler flue gas near the finished product tank area is in a normal use state, and performing four-stage condensation treatment on the waste gas recovered from the treatment of the intermediate tank area and the finished product tank area, and then discharging the waste gas reaching the standard; the condensation and absorption process is adopted, the four-stage condensation recovery and water absorption process is adopted in the middle tank area and the loading and unloading station, the four-stage condensation recovery and boiler co-firing process or the water absorption process is adopted in the finished product tank area and the loading and unloading station, the waste gas is treated, the organic matters are recovered, the tail gas in the coal chemical process is subjected to harmless treatment, the production cost is effectively reduced, the pollution emission is reduced, and the environment is protected.
Description
Technical Field
The application relates to the technical field of coal chemical industry machine recycling, in particular to an environment-friendly coal chemical industry VOC recycling method and system.
Background
With the improvement of environmental awareness, the national requirements for controlling the atmospheric pollution source are becoming stricter in recent years, and in the industrial production, the exhaust gas is more and more important, and the exhaust gas is composed of combustible and explosive toxic cancerogenic substances, so that the on-site operation environment is seriously influenced, and the physical and psychological health of operators is endangered, which is contrary to the requirements of modern industrial enterprises on humanity and environmental protection. Under the premise of ensuring safety, the oil storage warehouse, the oil tank truck and the oil gas recovery treatment of the gas station are mainly propelled; the traditional coal chemical industry has the problems that the waste gas in a tank area is discharged in an unorganized mode or is not thoroughly treated, and the like, the treatment requirement can be met in the initial operation stage, but continuous and stable standard-reaching discharge cannot be achieved on the treatment effect of the later operation, secondary pollution exists in the treatment process, the operation cost is high, the automation level is low, and zero discharge cannot be achieved.
Disclosure of Invention
In order to solve the problems, the application provides an environment-friendly coal chemical VOC recycling method and system thereof, which are used for more exactly solving the problems of unorganized emission or incomplete treatment and the like of most of waste gas in tank areas in the traditional coal chemical industry, and the problems of secondary pollution, high operation cost, low automation level, incapability of realizing zero emission and the like in the treatment process.
The application is realized by the following technical scheme:
the application provides an environment-friendly coal chemical VOC recycling method, which comprises the following steps of;
s1: introducing tail gas in coal chemical industry into a tank area tail gas collecting system, judging whether an initial pressure value in a tank is at a normal threshold value, if so, implementing monitoring of the pressure in the tank, adapting pressure regulation according to the pressure threshold value, and if not, adapting pressure reduction or once pressure by a pressure stabilizing device according to whether the initial pressure value is overpressure or underpressure;
s2: delivering the tail gas after being frozen and recovered in the middle tank area to a newly-added tail gas water scrubber for continuously supplementing desalted water, and circularly absorbing methanol by a circulating pump;
s3: identifying whether the boiler flue gas near the finished product tank area is in a normal use state, if so, sending the tail gas after freezing and recycling in the finished product tank area to an inlet of a secondary fan of the nearby boiler flue gas for co-firing;
s4: waste gas recovered from the middle tank area and the finished product tank area is subjected to four-stage condensation treatment, boosted by a fan, subjected to secondary water washing treatment and then discharged after reaching standards or discharged after reaching standards after being mixed and burned by a boiler.
Further, if yes, the step of monitoring the pressure in the tank and adapting and regulating the pressure according to the pressure threshold value comprises the following steps; if the pressure in the tank is lower than the opening set pressure of the nitrogen pressure stabilizing device 300PaG, the nitrogen pressure stabilizing device is opened; if the pressure in the tank is increased to 500 PaG, the nitrogen pressure stabilizing device is closed; when the pressure in the tank is gradually increased to 900Pa (G) along with the rising of the feeding or ambient temperature, the waste gas is discharged from an original exhaust pipeline through a single calling valve and is collected to a main pipe, and then the waste gas enters an exhaust gas treatment system.
Further, if not, the step of adapting the pressure reduction or the pressure-adding by the pressure stabilizing device according to whether the initial pressure value is the overpressure or the underpressure comprises the following steps; if the pressure in the tank is increased to 1765 PaG due to the blockage of the pipeline or other factors, the tail gas is directly discharged to the atmosphere from the breather valve, and if the pressure in the tank is increased to 1950PaG, the pressure relief manhole is opened for exhaust; if the pressure in the tank is reduced to 300PaG, the nitrogen self-operated regulating valve starts to be gradually opened for nitrogen supplementing treatment; if the pressure in the tank is reduced to-295 PaG, the breather valve sucks air to supplement the pressure in the tank, so that the pressure in the tank is always higher than-295 PaG.
Further, the step of sending the tail gas after being frozen and recovered in the middle tank area to a newly-added tail gas water scrubber for continuously supplementing desalted water, and the step of circularly absorbing methanol by a circulating pump comprises the following steps of; continuously discharging the methanol-containing wastewater after methanol absorption to a rectification external circulation analyzer V-3520 or a synthetic crude methanol flash tank V-3304.
Further, the step of identifying whether the boiler flue gas near the finished product tank area is in a normal use state comprises the following steps of; if not, introducing the tail gas into a tail gas washing tower by the waste gas for post-treatment; the water washing tower is continuously supplemented with desalted water, a circulating pump is additionally arranged, and the water washing tower is discharged after the methanol is absorbed in a circulating way.
If not, introducing the tail gas into a tail gas washing tower by the waste gas for post-treatment; the method comprises the steps of continuously supplementing desalted water into a water washing tower, adding a circulating pump, and circularly absorbing methanol and then discharging the methanol after reaching the standard; and continuously discharging the methanol-containing wastewater after methanol absorption into a wastewater pipe network for recovery treatment.
An environment-friendly coal chemical industry VOC recycling system, comprising;
a four-stage condensation recovery system; the device is used for condensing the waste gas and recycling harmful substances in the waste gas;
a middle tank block group; the device is used for storing and impurity removing treatment of intermediate tail gas in the tail gas treatment process;
a finished product tank group; the method is used for storing and further removing impurities of the tail gas after the tail gas treatment;
a combustion impurity removal system; back burning the waste gas to remove harmful substances in the waste gas and supplement heat to the factory;
a water absorption and impurity removal system; the device is used for absorbing and dissolving the waste gas and recycling harmful substances in the waste gas;
an analysis control system; the system is used for analyzing the data in each system and regulating and controlling the working state of each system in real time according to the data.
Further, the storage tanks in the middle tank group and the finished tank group are provided with a gas pressure stabilizing device, and the gas pressure stabilizing device regulates the pressure in the tank in real time through nitrogen sealing lines of different tanks.
The application has the beneficial effects that:
1. the application adopts condensation and absorption processes, the middle tank area and the loading and unloading station adopt a four-stage condensation recovery and water absorption method combination process, the finished product tank area and the loading and unloading station adopt a four-stage condensation recovery and boiler co-firing combination process or a water absorption method, waste gas is treated, organic matters are recovered, harmless treatment of tail gas in the coal chemical process is realized, resources are recycled, resources are recovered, the production cost is effectively reduced, pollution emission is reduced, and the method is more environment-friendly.
Drawings
FIG. 1 is a flow chart of a method for recycling VOC in coal chemical industry based on environmental protection;
fig. 2 is a system schematic diagram of the environment-friendly coal chemical VOC recycling system.
The realization, functional characteristics and advantages of the present application are further described with reference to the accompanying drawings in combination with the embodiments.
Description of the embodiments
In order to more clearly and completely describe the technical scheme of the application, the application is further described below with reference to the accompanying drawings.
Referring to fig. 1-2, the application provides an environment-friendly coal chemical industry VOC recycling method, which comprises the following steps of;
s1: introducing tail gas in coal chemical industry into a tank farm tail gas collection system, judging whether an initial pressure value in a tank is at a normal threshold value, if so, implementing monitoring of the pressure in the tank, adapting and regulating pressure according to the pressure threshold value, and if the pressure in the tank is lower than the opening set pressure of a nitrogen pressure stabilizing device 300PaG, opening the nitrogen pressure stabilizing device; if the pressure in the tank is increased to 500 PaG, the nitrogen pressure stabilizing device is closed; if the pressure in the tank is gradually increased to 900Pa (G) along with the rising of the feeding or ambient temperature, the waste gas is discharged from an original exhaust pipeline through a single calling valve and is collected to a main pipe, and then enters a tail gas treatment system; if not, the voltage stabilizing device adapts to the pressure reduction or the pressure-increasing according to the overpressure or the underpressure of the initial pressure value; if the pressure in the tank is increased to 1765 PaG due to the blockage of the pipeline or other factors, the tail gas is directly discharged to the atmosphere from the breather valve, and if the pressure in the tank is increased to 1950PaG, the pressure relief manhole is opened for exhaust; if the pressure in the tank is reduced to 300PaG, the nitrogen self-operated regulating valve starts to be gradually opened for nitrogen supplementing treatment; if the pressure in the tank is reduced to-295 PaG, the breather valve sucks air to supplement the pressure in the tank, so that the pressure in the tank is always higher than-295 PaG;
s2: delivering the tail gas after being frozen and recovered in the middle tank area to a newly-added tail gas water scrubber for continuously supplementing desalted water, and circularly absorbing methanol by a circulating pump; continuously discharging the methanol-containing wastewater after methanol absorption to a rectification external circulation analyzer V-3520 or a synthetic crude methanol flash tank V-3304;
s3: identifying whether the boiler flue gas near the finished product tank area is in a normal use state, if so, sending the tail gas after freezing and recycling in the finished product tank area to an inlet of a secondary fan of the nearby boiler flue gas for co-firing; if not, introducing the tail gas into a tail gas washing tower by the waste gas for post-treatment; the water washing tower is continuously supplemented with desalted water, a circulating pump is additionally arranged, and the water washing tower is discharged after the methanol is absorbed in a circulating way; continuously discharging the methanol-containing wastewater after methanol absorption into a wastewater pipe network for recovery treatment;
s4: waste gas recovered from the middle tank area and the finished product tank area is subjected to four-stage condensation treatment, boosted by a fan, subjected to secondary water washing treatment and then discharged after reaching standards or discharged after reaching standards after being mixed and burned by a boiler.
In the specific implementation, assuming that the initial pressure in the tank is 0, when the pressure in the tank is lower than the opening set pressure of the nitrogen pressure stabilizing device 300PaG, the nitrogen pressure stabilizing device is opened; when the pressure in the tank rises to 500 PaG, the nitrogen pressure stabilizing device is closed; at this time, the big tank is in a closed state, and neither exhales waste gas outwards nor breathes nitrogen inwards; when the pressure in the tank is gradually increased to 900PaG along with the increase of the feeding or ambient temperature, the waste gas is discharged from an original exhaust pipeline through a single calling valve and is collected to a main pipe and then enters a tail gas treatment system; an overpressure or an underpressure condition can occur in the tank; when the pressure in the tank rises to 1765 Pa (G) due to pipeline blockage or other factors, the tail gas is directly discharged to the atmosphere from the breather valve, and when the pressure continues to rise to 1950PaG, the pressure relief manhole opens the exhaust; when the pressure in the tank is reduced to 300PaG, the nitrogen self-operated regulating valve starts to be gradually opened, and nitrogen supplementing is started; when the pressure in the tank is reduced to-295 PaG, the breather valve sucks air to supplement the pressure in the tank, so that the pressure in the tank is always higher than-295 PaG;
the original waste gas collecting system can maintain the pressure in each big tank within 300-900 PaG under normal conditions, and under extreme conditions, the pressure ranges from-295 to 1950PaG and the pressure ranges from-500 to 2000 PaG; therefore, the exhaust gas is introduced into the existing exhaust gas recovery treatment system, so that the safety operation of each large tank can be ensured, and the exhaust gas can be recovered and utilized at the same time; after the waste gas in the tank area is recovered, the medium is composed of waste gas such as nitrogen, methanol and the like, most of the medium is nitrogen, the treatment facility is provided with four-stage condensation recovery, and after the waste gas is boosted by a fan, the waste gas is subjected to secondary water washing treatment and then is discharged after reaching standards or is discharged after being mixed with a boiler and burned; the energy can be recovered by utilizing heat exchange in the four-stage condensation, so that the energy consumption is reduced; the first stage reduces the gas temperature from ambient temperature to about 5 ℃; the second stage, the third stage and the fourth stage adopt a low-temperature refrigerating unit to reduce the gas temperature to about-70 ℃; the methanol liquid condensed and recovered in the middle tank area is pumped to a dirty methanol storage tank T-3603 for recovery; the methanol liquid condensed from the finished product tank area can be directly discharged to the underground storage tank T-3702 for recovery due to the normal pressure of the underground storage tank T-3702; considering the requirements of system safety and purity of the recovery liquid, in order to prevent a large amount of water from entering the cold box, the cryogenic unit is generally not allowed to start up and run when the set water dew point temperature is not reached; the refrigerating system consists of a refrigerating compressor, a condenser, an evaporator and other auxiliary equipment; the methanol content in the exhaust gas after deep cooling can be reduced to 0.133g/m 3 （0.099g/Nm 3 ) The method comprises the steps of carrying out a first treatment on the surface of the Delivering the tail gas subjected to freezing recovery in the middle tank area to a newly-added tail gas washing tower for post-treatment, and discharging the tail gas reaching the standard; continuous compensation of water washing towerFilling desalted water, adding a circulating pump, circularly absorbing methanol, continuously discharging methanol-containing wastewater after absorbing the methanol, and delivering the wastewater to a rectifying external circulation analyzer V-3520 or a synthetic crude methanol flash tank V-3304; delivering the tail gas after freezing recovery in the finished product tank area to an inlet of a secondary fan of the smoke gas of a nearby boiler for blending combustion, and discharging the tail gas after reaching the standard; the post-treatment is water washing when the boiler is stopped, and the tail gas water washing tower is subjected to post-treatment and then discharged after reaching standards; the water washing tower is continuously supplemented with desalted water, a circulating pump is additionally arranged, methanol is circularly absorbed, and methanol-containing wastewater after methanol absorption is continuously discharged and sent to a wastewater pipe network; the consumption of energy sources is effectively reduced, and the energy sources are recycled; the traditional tank farm waste gas treatment technology is a destruction technology, and basically converts a large amount of organic matters in oil gas into carbon dioxide to be discharged into the atmosphere, so that the problem of VOCs emission pollution is solved to a certain extent, but the following defects are present: (1) organic material cannot be recovered; all organic components in the oil gas are decomposed, and no resource is recovered; electricity or natural gas is additionally consumed; (2) Because the oil gas of the nitrogen seal storage tank contains almost no oxygen, the oxidation of organic matters is mainly carried out by matching air for supporting combustion; for various oxidation processes, people pay attention to not only the concentration of the organic matters measured by the exhaust gas discharge port, but also how much air is added before oxidation, and when the concentration of the exhaust gas is converted according to the amount of raw gas, the actual concentration data of the exhaust gas of many oxidation processes are greatly discounted, and some of the actual concentration data are even substandard; although the dilution here is unintended, it is an objective dilution in terms of environmental effect; in any case, the oxidation method always has the problem of converting useful organic matters and natural gas in oil gas into carbon dioxide, nitrogen oxides and the like to be discharged into the atmosphere; (3) security risks; various oxidation processes are carried out at high temperature, so that the problem of operation safety exists, and the condition that deflagration occurs in various oxidation processes happens; in addition to affecting the operation safety of the device, the problem of affecting the safety of the storage tank and surrounding facilities exists for the project; in which the threat to the safety of the tank cannot be completely eliminated, for example, if the nitrogen seal system fails, air enters the tank from the breather valve and eventually enters the reactor through the oil and gas system, where the entire oil and gas system may be inWithin the explosion limits; or the air distribution is abnormal, and the oil gas after the air distribution reaches the explosive combustion condition; despite countermeasures such as flame arresters, a small probability of such accident risk is sufficient to fear; (4) the occupied area is large; the oxidation method needs a larger safety distance, and other structures cannot be arranged around the device within a range of tens of meters. Although the occupied area of the device is relatively not quite large, the actual influence area of the project is often relatively large; the intermediate tank area and the loading and unloading station adopt a four-stage condensation recovery and water absorption method combined process, the finished product tank area and the loading and unloading station adopt a four-stage condensation recovery and boiler fan blending combustion combined process, and the recyclable methanol is subjected to condensation recovery and then water absorption treatment or boiler blending combustion, so that the final waste gas is ensured to reach the emission standard; the finished product tank field is close to a thermal power station boiler, the boiler is in the form of a circulating fluidized bed boiler, the air quantity of a secondary air blower is 91300m < 3 >/h, the rated quantity of waste gas in the finished product tank field is 3000Nm < 3 >/h, the discharge temperature is about 10 ℃, the inlet temperature of the air blower after accounting for mixed combustion is reduced by about 0.4 ℃, and the oxygen content is reduced from 20.6% mol to 20% mol in the original air; therefore, the influence on the system after the doping and burning is small;
the common point of the above processes is that most of the methanol is recovered and certain economic benefits can be produced, according to the amount of the waste gas and the composition of the waste gas, the recovery rate of the methanol is conserved by 80% wt, and the number of years is considered by 1000 h: the annual methanol recovery in the intermediate tank zone was calculated as follows: 692Nm3/h 0.032kg/mol 1000h 0.8/0.0224nm3/mol= 61.69t/a; the annual recovery methanol amount of the finished product tank field is calculated as follows: 2545Nm3/h 16%vol 0.032kg/mol 1000h 0.8/0.0224m3/mol= 465.37t/a; the total amount of the recovered methanol is 527.06t/a, and the annual cost is saved by 110.68 ten thousand yuan according to the consideration of 2100 yuan/ton of the methanol;
the finished product tank field is close to the boiler, and the boiler system serves the whole plant, so that the whole plant can not be stopped independently, and methanol loading is possible only during the whole plant stopping and overhauling period in large overhauling, so that the tail gas aftertreatment is required to be carried out by using a standby water scrubber in the period; a water washing tower is newly added in the middle tank area for water washing, and then the water is discharged after reaching the standard;
the waste gas is sent to a waste gas treatment facility through a collecting main pipe, and the waste gas firstly enters a return gas heat exchanger of a condensing device and the condensed waste gas (-70 ℃) is subjected to indirect cold recovery; at the moment, the temperature of the exhaust gas is reduced to about 5 ℃, moisture brought by the exhaust gas is removed, the exhaust gas enters a secondary freezing system for secondary freezing recovery, the temperature is reduced to about minus 30 ℃, the exhaust gas enters a tertiary freezing system, the temperature is reduced to minus 50 ℃ after freezing recovery, finally the exhaust gas is cooled to minus 70 ℃ by a fourth-stage cryogenic system, and the concentration of methanol at a non-condensable gas outlet of an evaporator of a fourth-stage cryogenic device is reduced to below 100 mg/Nm; the freezing solution adopts a glacier refrigerant or a medium with similar properties; the deep cooling device adopts a double-channel design, and when one path of frosting occurs, the system is automatically switched to the other path of system for condensation, so that continuous work can be realized; the frosted system enters a standby state after receiving the frost; the non-condensable gas from the cryogenic system is sent out by a fan; tail gas sent out by a fan: intermediate tank area: delivering the tail gas after freezing recovery to a newly-added tail gas water scrubber for post-treatment and then discharging the tail gas after reaching the standard; product tank field: delivering the tail gas after freezing recovery to an inlet of a secondary air blower of a nearby boiler for blending combustion, and discharging the tail gas after reaching the standard; the post-treatment is water washing when the boiler is stopped, and the tail gas water washing tower is subjected to post-treatment and then is discharged after reaching the standard.
An environment-friendly coal chemical VOC recycling system comprises; a four-stage condensation recovery system; the device is used for condensing the waste gas and recycling harmful substances in the waste gas; waste gas generated in the coal chemical industry is introduced into a tank area through a general conduit, and the temperature of the gas is reduced to about 5 ℃ from the ambient temperature in the first stage; the second stage, the third stage and the fourth stage adopt a low-temperature refrigerating unit to reduce the gas temperature to about-70 ℃ and condense and recycle the methanol liquid; a middle tank block group; the device is used for storing and impurity removing treatment of intermediate tail gas in the tail gas treatment process; the intermediate tank liquid is cooled and recovered, and the methanol liquid is pumped to a dirty methanol storage tank T-3603 for recovery; a finished product tank group; the method is used for storing and further removing impurities of the tail gas after the tail gas treatment; the methanol liquid condensed from the finished product tank area is directly discharged to a subsurface storage tank T-3702 in a self-flowing way for recovery; the storage tanks in the middle tank group and the finished tank group are provided with gas pressure stabilizing devices, and the gas pressure stabilizing devices regulate the pressure in the tanks in real time through nitrogen sealing lines of different tanks; a combustion impurity removal system; the waste gas is backfire, harmful substances in the waste gas are removed, heat is supplemented to a factory, the tail gas after freezing recovery is sent to an inlet of an original boiler flue gas secondary fan in the nearby coal chemical industry for blending combustion, and then the tail gas reaches the standard and is discharged; a water absorption and impurity removal system; the device is used for absorbing and dissolving the waste gas and recycling harmful substances in the waste gas; the tail gas water washing tower is used for continuously supplementing desalted water, a circulating pump is additionally arranged, methanol is circularly absorbed, and methanol-containing wastewater after methanol absorption is continuously discharged and sent to a wastewater pipe network; an analysis control system; the system is used for analyzing the data in each system and regulating and controlling the working state of each system in real time according to the data, and is connected with each system through a wire or a wireless connection module to transmit the data or instructions.
Of course, the present application can be implemented in various other embodiments, and based on this embodiment, those skilled in the art can obtain other embodiments without any inventive effort, which fall within the scope of the present application.
Claims (8)
1. The environment-friendly coal chemical VOC recycling method is characterized by comprising the following steps of;
s1: introducing tail gas in coal chemical industry into a tank area tail gas collecting system, judging whether an initial pressure value in a tank is at a normal threshold value, if so, implementing monitoring of the pressure in the tank, adapting pressure regulation according to the pressure threshold value, and if not, adapting pressure reduction or once pressure by a pressure stabilizing device according to whether the initial pressure value is overpressure or underpressure;
s2: delivering the tail gas after being frozen and recovered in the middle tank area to a newly-added tail gas water scrubber for continuously supplementing desalted water, and circularly absorbing methanol by a circulating pump;
s3: identifying whether the boiler flue gas near the finished product tank area is in a normal use state, if so, sending the tail gas after freezing and recycling in the finished product tank area to an inlet of a secondary fan of the nearby boiler flue gas for co-firing;
s4: waste gas recovered from the middle tank area and the finished product tank area is subjected to four-stage condensation treatment, boosted by a fan, subjected to secondary water washing treatment and then discharged after reaching standards or discharged after reaching standards after being mixed and burned by a boiler.
2. The environmental protection-based coal chemical industry VOC recycling method according to claim 1, wherein the step of performing pressure adjustment of the pressure in the monitoring tank according to the pressure threshold value comprises the following steps of; if the pressure in the tank is lower than the opening set pressure of the nitrogen pressure stabilizing device 300PaG, the nitrogen pressure stabilizing device is opened; if the pressure in the tank is increased to 500 PaG, the nitrogen pressure stabilizing device is closed; when the pressure in the tank is gradually increased to 900Pa (G) along with the rising of the feeding or ambient temperature, the waste gas is discharged from an original exhaust pipeline through a single calling valve and is collected to a main pipe, and then the waste gas enters an exhaust gas treatment system.
3. The method for recycling the VOC in the coal chemical industry based on the environment protection according to claim 1, wherein if not, the step of adapting the pressure reduction or the previous pressure by the pressure stabilizing device according to the overpressure or the underpressure of the initial pressure value comprises the following steps of; if the pressure in the tank is increased to 1765 PaG due to the blockage of the pipeline or other factors, the tail gas is directly discharged to the atmosphere from the breather valve, and if the pressure in the tank is increased to 1950PaG, the pressure relief manhole is opened for exhaust; if the pressure in the tank is reduced to 300PaG, the nitrogen self-operated regulating valve starts to be gradually opened for nitrogen supplementing treatment; if the pressure in the tank is reduced to-295 PaG, the breather valve sucks air to supplement the pressure in the tank, so that the pressure in the tank is always higher than-295 PaG.
4. The environmental protection-based coal chemical industry VOC recycling method according to claim 1, wherein the step of sending the tail gas after freezing and recycling in the middle tank area to a newly-added tail gas water scrubber for continuously supplementing desalted water and circularly absorbing methanol by a circulating pump comprises the following steps of; continuously discharging the methanol-containing wastewater after methanol absorption to a rectification external circulation analyzer V-3520 or a synthetic crude methanol flash tank V-3304.
5. The environmental protection-based coal chemical industry VOC recycling method according to claim 1, wherein the step of identifying whether the boiler flue gas near the finished product tank area is in a normal use state comprises the following steps of; if not, introducing the tail gas into a tail gas washing tower by the waste gas for post-treatment; the water washing tower is continuously supplemented with desalted water, a circulating pump is additionally arranged, and the water washing tower is discharged after the methanol is absorbed in a circulating way.
6. The environment-friendly coal chemical industry VOC recycling method according to claim 5, wherein if not, the exhaust gas introduces the exhaust gas into an exhaust gas washing tower for post-treatment; the method comprises the steps of continuously supplementing desalted water into a water washing tower, adding a circulating pump, and circularly absorbing methanol and then discharging the methanol after reaching the standard; and continuously discharging the methanol-containing wastewater after methanol absorption into a wastewater pipe network for recovery treatment.
7. An environment-friendly coal chemical industry VOC recycling system for the environment-friendly coal chemical industry VOC recycling method of claims 1-6, characterized in that the recycling system comprises;
a four-stage condensation recovery system; the device is used for condensing the waste gas and recycling harmful substances in the waste gas;
a middle tank block group; the device is used for storing and impurity removing treatment of intermediate tail gas in the tail gas treatment process;
a finished product tank group; the method is used for storing and further removing impurities of the tail gas after the tail gas treatment;
a combustion impurity removal system; back burning the waste gas to remove harmful substances in the waste gas and supplement heat to the factory;
a water absorption and impurity removal system; the device is used for absorbing and dissolving the waste gas and recycling harmful substances in the waste gas;
an analysis control system; the system is used for analyzing the data in each system and regulating and controlling the working state of each system in real time according to the data.
8. The environment-friendly coal chemical industry VOC recycling system is characterized in that a gas pressure stabilizing device is arranged in storage tanks in the middle tank group and the finished tank group, and the gas pressure stabilizing device regulates the pressure in the tank in real time through nitrogen sealing lines of different tanks.
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