Nitrogen-sealed storage tank waste gas treatment and nitrogen recycling device

Abstract

The utility model provides a waste gas treatment and nitrogen recycling device for a nitrogen-sealed storage tank, and belongs to the field of petroleum, petrochemical and environmental protection. The device comprises a condensation system, waste gas is connected with a waste gas condensation system through a precooler, and the output end of the waste gas condensation system is connected with a chimney through the precooler and an adsorption tank. According to the utility model, logic control programs with different time sequences are arranged at the key points of the whole process of condensation, frosting, adsorption and desorption separation, so that the tail gas is efficiently and thoroughly separated, and the nitrogen recycling purity is stably achieved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the petroleum petrochemical, environmental protection field relates to a nitrogen seal storage tank waste gas treatment and nitrogen recycling device. TECHNICAL BACKGROUND

[0002] The VOCs concentration of the gas emitted by the petroleum petrochemical tank top is too high, cannot satisfy the environmental protection regulation requirement, must be managed, generally, the VOCs content in nitrogen seal gas is only below 5% of the exhaust gas, and the high nitrogen-containing tail gas is directly discharged into the atmosphere, causing resource waste. In order to save the device operation cost, realize the near zero discharge of tank area waste gas, the nitrogen seal nitrogen of storage tank needs to be treated and recycled.

[0003] At present, the protective nitrogen gas for the storage tank of petrochemical enterprise is produced by air separation device uniformly, and the nitrogen gas with the purity of not less than 99.99% (V%) is produced according to the standard of "petrochemical enterprise nitrogen oxygen system design specification" (SH / T3106) to satisfy the use requirement of production device, and the purity of the nitrogen gas treated by the patent is not less than 99.99% (V%), which can satisfy the nitrogen requirement of the nitrogen seal of storage tank.

[0004] The conventional tail gas separation and purification technology is difficult to stably reach the 99.99% purity requirement of nitrogen recycling.

[0005] In order to guarantee the safety of the storage tank and waste gas collection system, generally, the oxygen concentration of atmospheric pressure storage tank and waste gas collection system needs to be maintained to be less than 6% (according to the different material composition, can be adjusted), that is, to be reduced to the limit oxygen demand of 60% below required by waste gas explosion.

[0006] Therefore, the energy storage condensation and multistage adsorption patent process are adopted to realize the stable and standard discharge of tank area waste gas, and the tail gas (that is, the recycled nitrogen) separated and purified directly returns to the nitrogen pipe network, which can solve the environmental protection problem caused by the discharge of storage tank waste gas, realizes the nitrogen recycling, and has no waste gas discharge under normal working conditions. In order to guarantee the safety of the storage tank and waste gas collection system, it is also extremely important to control the oxygen content in the recycled nitrogen. CONTENT OF UTILITY MODEL

[0007] In view of the tank area waste gas treatment problem, the purpose of the utility model is to provide a tank area waste gas treatment and nitrogen recycling mode with mature and reliable process, high safety, good treatment effect, low equipment investment and low operation and maintenance cost. The scheme uses the advanced energy storage high-efficiency condensation and multistage adsorption purification process as the recycling basis, continuously and stably provides the purified tail gas (that is, the recycled nitrogen) with the purity of greater than or equal to 99.99%, realizes that the waste gas reaches the national and local standards. When the storage tank breathes in and out, the oxygen content detector is arranged on the exhaust tail gas pipeline, and the safety of the purified tail gas into the storage tank is guaranteed.

[0008] The purpose of the utility model can be realized by the following technical schemes.

[0009] A nitrogen seal tank exhaust treatment and nitrogen recycling device, the device comprises a condensing system, exhaust is connected with exhaust condensing system through pre-cooler, the output end of the exhaust condensing system is connected with chimney through pre-cooler through adsorption tank.

[0010] The utility model technical scheme, the condensing system is matched with the refrigerant storage tank.

[0011] The utility model technical scheme, the condensing system includes parallelly connected exhaust condensing system A and exhaust condensing system B, and the two output ends of the refrigerant storage tank are connected with exhaust condensing system A and exhaust condensing system B respectively, and branch is equipped on the output pipeline, and the branch is connected with the refrigerant storage tank.

[0012] The utility model technical scheme, the output end of the bottom of exhaust condensing system A and exhaust condensing system B is connected with the boundary through condensate storage tank.

[0013] The utility model technical scheme, the adsorption tank includes parallelly connected adsorption tank A and adsorption tank B, the top of adsorption tank is connected with chimney, and the output end of the bottom is connected with exhaust buffer tank.

[0014] The utility model technical scheme, exhaust buffer tank is connected with pre-cooler through exhaust fan.

[0015] The utility model technical scheme, the output end of the top of adsorption tank is connected with nitrogen storage tank through valve, nitrogen buffer tank and compressor in proper order.

[0016] The utility model technical scheme, one output end of nitrogen storage tank is connected with chimney through valve, and the other output end is connected with the output end of the top of adsorption tank through nitrogen protection system.

[0017] The utility model technical scheme, tank area exhaust treatment adopts energy storage condensation and multistage adsorption technology, removes organic matter and impurity in exhaust, and makes the nitrogen concentration of the purified gas after treatment reach above 99.99%, and the purified gas reaches the standard, and nitrogen is recycled back to tank area again.

[0018] The utility model technical scheme, for the condition that tank area exhaust pressure is low, adopts fan (centrifugal fan, reciprocating fan) to overcome the resistance of pipeline, condensation and adsorption system, adopts piston compressor, improves the exhaust pressure after purification, and realizes that exhaust returns to tank area again and realizes recycling.

[0019] The utility model technical scheme, adsorption unit sets up adsorbent protection system to improve the adsorption effect of adsorbent, and nitrogen comes from high-pressure nitrogen storage tank.

[0020] The utility model discloses a technical scheme: realize the key point of the whole process of condensation, defrosting, adsorption, desorption according to time sequence logic automatic control, ensure that the tail gas separation is efficient and thorough, reach the nitrogen reuse purity.

[0021] The specific technical scheme is:

[0022] Tank area waste gas treatment adopts energy storage condensation and multistage adsorption process, removes N2 concentration in the exhaust gas to reach 99.99% or above, and reaches the standard of waste gas, simultaneously realizes that nitrogen gas is reused in tank area again;

[0023] The exhaust gas header sets up oxygen content analyzer, under normal circumstances, the tail gas enters high-pressure nitrogen gas storage tank temporary storage through the compressor, when the oxygen content in the tail gas is higher than the safety value, the tail gas enters the chimney and is discharged.

[0024] For the condition that the pressure of tank area waste gas is low, adopt the fan (centrifugal fan, reciprocating fan) to overcome the resistance of pipeline and condensation adsorption system, adopt the piston compressor to improve the pressure of the tail gas after purification, realize that the tail gas returns to the tank area and realizes reuse.

[0025] The application provides energy storage condensation technology, fundamentally solves the key technology that one of the defrosting is not thorough, influences the tail gas separation effect, causes the nitrogen purity to be not enough which cannot be avoided in conventional condensation process.

[0026] The application is according to the characteristics of different organic matters in the tail gas, and different adsorbents are respectively laid in the adsorption tower, which is the core equipment for ensuring the purity of the recovered nitrogen.

[0027] The utility model sets up adsorbent maintenance facilities in the adsorption unit, regularly carries out active maintenance to the adsorption tower, keeps the adsorbent in the best adsorption environment, and provides reliable guarantee for the recovered nitrogen.

[0028] The recovered nitrogen is stored in the pressure nitrogen storage tank, and the nitrogen reuse flow of the system is adjusted.

[0029] The utility model realizes the key point of the whole process of condensation, defrosting, adsorption and desorption separation, and different time sequence logic control programs are arranged, so that the tail gas separation is efficient and thorough, and the nitrogen reuse purity is stable. DETAILED DESCRIPTION

[0030] Figure 1 It is the structure schematic drawing of the utility model.

[0031] Figure, 1. waste gas buffer tank, 2. waste gas fan, 3. pre-cooler, 4. waste gas condensing system A, 5. waste gas condensing system B, 6. condensate storage tank, 7. refrigerant storage tank, 8. defrosting agent storage tank, 9. condensate delivery pump, 10. adsorption tank A, 11. adsorption tank B, 12. vacuum pump, 13. compressor, 14. nitrogen storage tank, 15. nitrogen protection system, 16. nitrogen buffer tank, 17. first control valve, 18. second control valve, 19. chimney. DETAILED DESCRIPTION

[0032] The application will be described in detail below in conjunction with the drawings and specific examples.

[0033] As Figure 1 shown, a nitrogen seal storage tank waste gas treatment and nitrogen recycling device, the device includes a condensing system, waste gas through the pre-cooler 3 and waste gas condensing system is connected, the output end of the waste gas condensing system through the pre-cooler 3 through the adsorption tank and chimney 19 is connected. The condensing system is matched with refrigerant storage tank 7. Condensing system includes parallel waste gas condensing system A 4 and waste gas condensing system B 5; the two output ends of the refrigerant storage tank 7 are connected with waste gas condensing system A 4 and waste gas condensing system B 5 respectively, and a branch is provided on the output pipeline, which is connected with the refrigerant storage tank 7. The output end of the bottom of the waste gas condensing system A 4 and the waste gas condensing system B 5 is connected with the outside through the condensate storage tank 6. The adsorption tank includes parallel adsorption tank A 10 and adsorption tank B 11, the top of the adsorption tank is connected with the chimney, and the output end of the bottom is connected with the waste gas buffer tank 1. The waste gas buffer tank 1 is connected with the pre-cooler 3 through the waste gas fan 2. The output end of the top of the adsorption tank is connected with the nitrogen storage tank 14 through the valve, the nitrogen buffer tank 16 and the compressor 13 in turn. One output end of the nitrogen storage tank 14 is connected with the chimney through the valve, and the other output end is connected with the output end of the top of the adsorption tank through the nitrogen protection system 15.

[0034] The specific method is as follows:

[0035] The low pressure VOCs waste gas generated by the storage tank storing alcohol, ester and ether is collected through the waste gas collection pipeline, first enters the waste gas buffer tank 1, and then enters the waste gas fan 2 for pressure boosting.

[0036] The tail gas enters the energy storage condensing unit for separation of high concentration organic matter. The energy storage condensing unit comprises a pre-cooler 3, a condenser 4, a condenser 5, an energy storage device 7, and the pre-cooler 3 (plate type, column type, spiral plate type) realizes preliminary cooling of the source waste gas through heat exchange between the raw material waste gas and the condensed waste gas, thereby achieving energy saving. The condensers 4 and 5 (plate type, column type, fin type) use low-temperature refrigerant (5℃ to -85℃), mainly undertake condensation and separation of most of the organic matter and impurities in the tail gas, and the waste gas is cooled to the required value (10℃ to -70℃) by the refrigerant from the energy storage device in the condenser, thereby separating most of the organic matter and impurities. The defrosting of the heat exchanger uses a heat medium, and after defrosting, the condensed liquid enters the condensed liquid tank 6, and then is transported to the outside by the condensed liquid pump 9. The energy storage device X-101 (including an ice machine, a heat exchanger, a shield pump, and a magnetic pump) provides cold and hot media to provide energy for condensation and defrosting.

[0037] The adsorption unit comprises an adsorption tower 10, an adsorption tower 11, a vacuum pump 12, a control valve 17, and a nitrogen protection system 15. The tail gas enters the adsorption tower (containing a combined adsorbent: carbon-based adsorbent, molecular sieve adsorbent, and resin adsorbent),

[0038] After the organic matter and impurities in the tail gas are adsorbed by the adsorbent, the purity of the tail gas is not less than 99.99% (V%), and the tail gas is discharged from the top of the adsorption tank.

[0039] When the adsorption tower enters the desorption process, the vacuum pump 12 (screw type or claw type) provides power (1Pa to 3000Pa) for the desorption of the adsorption tower. The desorption gas returns to the front-end buffer tank 1 and then enters the system together with the waste gas for treatment. After the above process, the organic matter and impurities in the tail gas are completely separated, and the purity of the obtained tail gas is not less than 99.99% (V%), thereby meeting the requirements for reuse.

[0040] The nitrogen protection system 15 (electric heater, steam heater, hot water heater) regularly maintains the activity of the adsorption tower, so that the adsorbent is always in the best adsorption environment, thereby providing reliable protection for the recovered nitrogen gas.

[0041] The recovered nitrogen gas is composed of a nitrogen compressor 13, a nitrogen storage tank 14, a nitrogen buffer tank 16, a control valve 17, and a control valve 18. The recovered nitrogen gas is stored in the nitrogen buffer tank 16, pressurized by the nitrogen compressor 13 (centrifugal type) (0.2MPa to 1.0MPa) into the nitrogen storage tank 14 (horizontal type, vertical type, or spherical type) for standby use. The control valves 17 and 18 adjust the flow of the reuse system.

[0042] The key points of the whole process of condensation, defrosting, adsorption, and desorption separation in the patent are provided with different time sequence logic control programs, which ensure efficient and complete separation of the tail gas and stable nitrogen reuse purity. The condensation low-temperature and high-temperature control valves (pneumatic control valves or electric control valves) are randomly controlled.

Claims

1. A device for treating exhaust gas from a nitrogen-sealed storage tank and for nitrogen recycling, characterized in that: The device comprises a condensing system, the exhaust gas is connected with the exhaust gas condensing system through a pre-cooler (3), the output end of the exhaust gas condensing system is connected with a chimney (19) through the pre-cooler (3) and an adsorption tank; The condensing system comprises exhaust gas condensing system A (4) and exhaust gas condensing system B (5) in parallel; two output ends of the refrigerant storage tank (7) are respectively connected with exhaust gas condensing system A (4) and exhaust gas condensing system B (5); a branch is arranged on the output pipeline and connected with the refrigerant storage tank (7); The output end at the top of the adsorption tank is connected with a nitrogen storage tank (14) through a valve, a nitrogen buffer tank (16) and a compressor (13) in sequence; One output end of the nitrogen storage tank (14) is connected with the chimney through a valve, and the other output end is connected with the output end at the top of the adsorption tank through a nitrogen protection system (15).

2. The apparatus for treating exhaust gas of a nitrogen sealed tank and recycling the nitrogen gas according to claim 1, characterized in that: The condensing system is matched with a refrigerant storage tank (7).

3. The apparatus for treating exhaust gas of a nitrogen sealed tank and recycling the nitrogen gas of claim 1, wherein: The output ends at the bottoms of exhaust gas condensing system A (4) and exhaust gas condensing system B (5) are connected with an out-of-boundary through a condensate storage tank (6).

4. The apparatus for treating vent gas from a nitrogen sealed storage tank and recovering nitrogen gas of claim 1, wherein: The adsorption tank comprises adsorption tank A (10) and adsorption tank B (11) in parallel; the top of the adsorption tank is connected with the chimney, and the output end at the bottom is connected with an exhaust gas buffer tank (1).

5. The apparatus for treating exhaust gas from a nitrogen sealed tank and recycling the nitrogen gas according to claim 4, characterized by: The exhaust gas buffer tank (1) is connected with the pre-cooler (3) through an exhaust gas fan (2).

Images