System for adsorbing and recovering solvent from tail gas of leaching workshop

Abstract

The utility model discloses a leaching workshop tail gas adsorption and solvent recovery system, which is characterized in that an outlet of a leaching workshop tail gas pipe is connected with a tail gas inlet in the side wall of the lower part of each resin adsorption tower through a tail gas fan, and a tail gas outlet in the center of the top of each resin adsorption tower is connected with a discharge fan and a discharge pipeline; a desorption steam inlet and a desorption air inlet are respectively formed in the top of each resin adsorption tower, and the steam pipeline is connected with each desorption steam inlet; outlets of the cold air inlet pipe and the DC hot air pipe are respectively connected with an inlet of the induced draft fan, and an outlet of the induced draft fan is connected with each desorption air inlet; a desorption gas outlet in the center of the bottom of each resin adsorption tower is connected with a shell pass inlet of the condenser through a desorption gas outlet pipe, a shell pass gas outlet of the condenser is connected with a condenser gas outlet pipe, and a shell pass liquid outlet of the condenser is connected with a solvent condensate collecting pipe. The system can greatly reduce the concentration of non-methane total hydrocarbon in the tail gas, ensures that the emission standard requirement is met, and can realize long-term low-investment stable and safe production.

Description

Technical Field

[0001] The utility model relates to a tail gas adsorption system, in particular to a solvent adsorption and recovery system for the tail gas of a leaching workshop, belonging to the technical field of tail gas treatment equipment. Background Art

[0002] According to the Integrated Emission Standard of Air Pollutants GB16297-1996, the maximum allowable emission concentration of non-methane total hydrocarbons is 120 mg / m³. At present, most of the n-hexane in the production system of the leaching workshop is recovered after condensation and reused, and a small amount enters the mineral oil absorption system. The tail gas treated by the mineral oil absorption system cannot be completely absorbed, and there is an over-standard phenomenon when the concentration fluctuates. After testing, under the existing treatment process conditions, the tail gas emission concentration of the leaching workshop can reach 15000 mg / m³, which does not meet the requirements of up-to-standard emission, and at the same time affects environmental safety, running counter to the concept of safe and environmental protection production. In order to meet the requirements of air emission and ensure stable and up-to-standard emission, it is necessary to deeply treat the tail gas of the leaching workshop.

[0003] The adsorption resin has a porous three-dimensional structure and physically adsorbs volatile organic compounds (VOCs) in the tail gas through van der Waals forces, thereby effectively reducing the content of non-methane total hydrocarbons in the tail gas and reaching the emission standard specified in the Integrated Emission Standard of Air Pollutants. The adsorption resin has the advantages of high micropore volume, high specific surface area (up to more than 2000 m³ / g), good mechanical strength, easily adjustable pore structure and surface chemistry, and renewable property, and has great advantages in the treatment of the tail gas of the leaching workshop.

[0004] At present, there are many methods for adsorbing the tail gas of the leaching workshop in China, mainly including the following:

[0005] The Chinese utility model patent with the publication number CN 208694600U discloses a tail gas treatment device for a leaching workshop in a soybean pressing factory, which mainly includes a lithium bromide refrigerator and a shell-and-tube heat exchanger. Using the industrial circulating water in the soybean pressing workshop as the heat source of the lithium bromide refrigerator, the industrial circulating water at 25-30 °C is made into chilled water at 5-8 °C after passing through the lithium bromide refrigerator. Using this chilled water as a low-temperature heat exchange medium, heat exchange is carried out with the n-hexane tail gas in the leaching workshop through the shell-and-tube heat exchanger to condense the gaseous n-hexane into liquid n-hexane, reducing the emission of n-hexane. This technical solution has less harm to safety production, the equipment cost is invested once, and the industrial circulating water in the workshop is effectively utilized, reducing the production cost, but it does not reduce the content of VOCs in the tail gas, and it will still harm the environment when discharging.

[0006] The Chinese utility model patent with the publication number CN 209662968 discloses a tail gas absorption system for an oil leaching workshop, which includes a paraffin oil absorption unit and an activated carbon absorption unit. The activated carbon absorption unit mainly includes an activated carbon adsorption tower connected to the exhaust end of the paraffin oil absorption tower and a desorption component capable of solvent desorption of the activated carbon adsorption tower. There are two activated carbon adsorption towers, one is a working group and the other is a standby group. When adsorbing, one of the activated carbon adsorption towers is connected to the paraffin oil absorption tower. When one of the activated carbon adsorption towers is in a saturated adsorption state, the activated carbon adsorption tower in the saturated state stops introducing the gas discharged from the paraffin oil absorption tower, and switches to connect the other activated carbon adsorption tower to the paraffin oil absorption tower. The activated carbon in this technical solution can effectively adsorb VOCs in the tail gas, but the activated carbon has the disadvantages of incomplete desorption, low mechanical strength, easy breakage resulting in an increase in equipment pressure drop, easy deterioration and spontaneous combustion of the carbon layer, and the need for regular replacement. Moreover, when the activated carbon adsorption and desorption process is used to treat halogenated hydrocarbons, hydrolysis is likely to occur during steam desorption to produce hydrochloric acid, which causes corrosion and damage to the equipment. The long-term use investment cost is relatively high and safety problems are likely to occur during production, endangering production and the safety of operators. Utility Model Content

[0007] The purpose of this part is to outline some aspects of the embodiments of the present utility model and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, as well as in the abstract of the specification and the title of the utility model of this application, to avoid obscuring the purpose of this part, the abstract of the specification and the title of the utility model. However, such simplifications or omissions shall not be used to limit the scope of the present utility model.

[0008] In view of the above and / or problems existing in the prior art, the present utility model is proposed.

[0009] The purpose of the present utility model is to overcome the problem of high tail gas emission concentration in the leaching workshop in the prior art, and provide a tail gas adsorption and solvent recovery system for the leaching workshop, which can greatly reduce the concentration of non-methane total hydrocarbons in the tail gas, ensure compliance with the emission standard requirements, and achieve the goal of long-term low investment and stable and safe production.

[0010] To solve the above technical problems, a tail gas adsorption and solvent recovery system for an oil leaching workshop of the present utility model includes an oil leaching workshop tail gas pipe. The outlet of the oil leaching workshop tail gas pipe is connected to the inlet of a tail gas fan. The outlet of the tail gas fan is connected to the tail gas inlet at the lower side wall of each resin adsorption tower through a tail gas inlet valve. The tail gas outlets at the centers of the tops of each resin adsorption tower are respectively connected to the inlet of an exhaust fan through a tail gas outlet valve. The outlet of the exhaust fan is connected to an exhaust pipe.

[0011] At the top of each resin adsorption tower, there are also a desorption steam inlet and a desorption air inlet respectively. The steam pipeline is connected to the desorption steam inlet of each resin adsorption tower through a steam valve; the outlet of the cold air inlet pipe is connected to the inlet of the induced draft fan through a cold air valve, the outlet of the DC hot air pipe is connected to the inlet of the induced draft fan through a hot air valve, and the outlet of the induced draft fan is connected to the desorption air inlet at the top of each resin adsorption tower through a desorption air valve;

[0012] At the center of the bottom of each resin adsorption tower, there is a desorption gas outlet. Each desorption gas outlet is respectively equipped with a desorption gas outlet valve. The outlets of each desorption gas outlet valve are all connected to the inlet of the shell side of the condenser through a desorption gas outlet pipe. The exhaust port of the shell side of the condenser is connected to a condenser exhaust pipe, and the liquid discharge port of the shell side of the condenser is connected to a solvent condensate collection pipe.

[0013] Furthermore, a VOCs detector is installed on the inlet pipeline of the discharge fan.

[0014] Furthermore, a VOCs detector is also installed on the side wall of the outlet of the desorption gas outlet pipe.

[0015] Furthermore, the outlet of the tail gas fan is also connected to the inlet of the discharge fan through an emergency discharge valve and a bypass air pipe.

[0016] Furthermore, two resin adsorption towers are arranged in parallel.

[0017] Furthermore, metal sintered meshes are respectively arranged on the upper and lower cross-sections of the inner cavity of the resin adsorption tower. The adsorption resin is filled above the lower metal sintered mesh, and the upper metal sintered mesh is located above the resin layer to prevent the resin from flying out.

[0018] Furthermore, the tail gas inlet of the resin adsorption tower is located below the lower metal sintered mesh. Temperature gauge interfaces are respectively arranged on the peripheral wall above the lower metal sintered mesh and the peripheral wall below the upper metal sintered mesh. A pressure gauge interface is also arranged on the peripheral wall above the lower metal sintered mesh.

[0019] Furthermore, a manhole sight glass that can be opened and closed and observed is arranged on the circumferential wall between the upper and lower metal sintered meshes.

[0020] Furthermore, there are two manhole sight glasses, which are respectively close to the top and bottom of the resin.

[0021] Compared with the prior art, the utility model has achieved the following beneficial effects: 1. After being treated by this system, the VOCs emission concentration of the tail gas in the leaching workshop can be reduced from 15000 mg / m³ to below 30 mg / m³, far lower than the emission standard requirement of 120 mg / m³, solving the problem of difficult tail gas emission in the leaching workshop and at the same time facilitating environmental protection production.

[0022] 2. Taking the soybean leaching workshop with a capacity of 5000 TPD as an example, after adding the tail gas adsorption and recovery system, the n-hexane recovery amount can reach 225 kg / d, reducing the n-hexane consumption in the production process.

[0023] 3. The recovered n-hexane can reduce the annual production cost of the factory. After considering the resin consumption cost for a full replacement of the resin in the tail gas adsorption and recovery system every 5 years, the 5000 TPD soybean leaching workshop can still save 846,000 yuan annually. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings. The drawings are only for reference and explanation, and are not used to limit the present invention. Among them:

[0025] Figure 1 It is the flow chart of the tail gas adsorption and recovery solvent system for the leaching workshop of the present invention;

[0026] Figure 2 It is the front view of the resin adsorption tower of the present invention;

[0027] Figure 3 It is the cross-sectional view of the resin adsorption tower without filled resin;

[0028] In the figure: T1. Resin adsorption tower 1; T2. Resin adsorption tower 2; PT. Pressure sensor; TT. Temperature sensor; FT. On-line humidity meter; VOC. VOCs detector;

[0029] F1. Tail gas fan; F2. Induced draft fan; F3. Discharge fan; E1. Condenser;

[0030] V1. Tail gas inlet valve; V2. Tail gas outlet valve; V3. Steam valve; V4. Cold air valve; V5. Hot air valve; V6. Desorption air valve; V7. Desorption outlet gas valve; V8. Emergency discharge valve;

[0031] G1. Tail gas pipe of the leaching workshop; G2. Cold air inlet pipe; G3. DC hot air pipe; G4. Steam pipe; G5. Discharge pipe; G6. Condenser exhaust pipe; G7. Solvent condensate collection pipe; G8. Circulating water inlet pipe; G9. Circulating water outlet pipe; G10. Desorption outlet gas pipe; G11. By-pass air pipe;

[0032] 1. Desorption steam inlet; 2. Tail gas outlet; 3. Desorption air inlet; 4. Safety valve interface; 5. Tail gas inlet; 6. Desorption gas outlet; 7. Thermometer interface; 8. Pressure gauge interface; 9. Manhole sight glass; 10. Metal sintered mesh. Detailed implementation manners

[0033] In the following description of the present utility model, the orientation or positional relationships indicated by the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating that the device must have a specific orientation.

[0034] In order to make the technical means, creative features, achieved purposes and effects realized by the present utility model easy to understand, the present utility model will be further described below with reference to specific illustrations. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present utility model belongs. The terms used in the description of the present utility model herein are only for the purpose of describing specific embodiments, and are not intended to limit the present utility model.

[0036] As Figures 1 to 3 shown, the tail gas adsorption and solvent recovery system of the leaching workshop of the present utility model includes a tail gas pipe G1 of the leaching workshop, a resin adsorption tower T1 and a resin adsorption tower T2. The outlet of the tail gas pipe G1 of the leaching workshop is connected to the inlet of a tail gas fan. An on-line hygrometer FT is installed at the outlet of the tail gas fan F1, and the outlet end of the tail gas fan F1 is connected to the tail gas inlet 5 on the lower side walls of the resin adsorption tower T1 and the resin adsorption tower T2 through a tail gas inlet valve V1. The tail gas outlets 2 at the centers of the tops of the resin adsorption tower T1 and the resin adsorption tower T2 are respectively connected to the inlets of an exhaust fan F3 through tail gas outlet valves V2. A VOCs detector is installed on the inlet pipe of the exhaust fan F3, and the outlet of the exhaust fan F3 is connected to an exhaust pipe G5.

[0037] Metal sintered meshes 10 are respectively provided on the upper and lower cross-sections of the inner cavity of the resin adsorption tower. Adsorption resin is filled above the lower metal sintered mesh, and the upper metal sintered mesh is located above the resin layer to prevent the resin from flying out.

[0038] The tail gas inlet 5 of the resin adsorption tower is located below the lower metal sintered mesh. Thermometer interfaces 7 are respectively provided on the circumferential walls above the lower metal sintered mesh and below the upper metal sintered mesh, and a pressure gauge interface 8 is also provided on the circumferential wall above the lower metal sintered mesh.

[0039] A manhole sight glass 9 that can be opened, closed and observed is provided on the circumferential wall between the upper and lower metal sintered meshes. Usually, there are two manhole sight glasses 9, which are respectively close to the top and bottom of the resin.

[0040] At the top of the first resin adsorption tower T1 and the second resin adsorption tower T2, there are also provided a desorption steam inlet 1, a desorption air inlet 3 and a safety valve interface 4 respectively. The steam pipeline G4 is connected to the desorption steam inlet 1 of the first resin adsorption tower T1 and the second resin adsorption tower T2 through a steam valve V3; the outlet of the cold air inlet pipe G2 is connected to the inlet of the induced draft fan F2 through a cold air valve V4, and the outlet of the DC hot air pipe G3 is connected to the inlet of the induced draft fan F2 through a hot air valve V5. An on-line hygrometer FT is installed at the outlet of the induced draft fan F2, and the outlet end of the induced draft fan F2 is connected to the desorption air inlet 3 at the top of the first resin adsorption tower T1 and the second resin adsorption tower T2 through a desorption air valve V6;

[0041] At the center of the bottom of the first resin adsorption tower T1 and the second resin adsorption tower T2, there are desorption gas outlets 6. Each desorption gas outlet 6 is respectively equipped with a desorption gas outlet valve V7. The outlets of each desorption gas outlet valve V7 are all connected to a desorption gas outlet pipe G10. The side wall of the outlet end of the desorption gas outlet pipe G10 is also equipped with a VOCs detector. The outlet of the desorption gas outlet pipe G10 is connected to the shell-side inlet of the condenser E1. The shell-side exhaust port of the condenser E1 is connected to the condenser exhaust pipe G6, and the shell-side drain port of the condenser E1 is connected to the solvent condensate collection pipe G7.

[0042] The outlet of the tail gas fan F1 is also connected to the inlet of the discharge fan F3 through an emergency discharge valve V8 and a bypass air pipe G11. In case of an emergency, the emergency discharge valve V8 can be opened, and the gas can be discharged to the outside through the bypass air pipe G11 and the discharge fan F3.

[0043] The tail gas after being absorbed by the mineral oil in the leaching workshop enters the first resin adsorption tower T1 through the tail gas fan F1 and the tail gas inlet valve V1 of the leaching workshop tail gas pipe G1. The tail gas fan F1 is frequency-controlled and can be interlocked with the pressure sensor at the inlet of the tail gas fan to regulate the amount of tail gas entering the tail gas adsorption and recovery system, ensuring that the VOCs in the tail gas are reduced to below the emission standard after passing through the resin adsorption tower. The tail gas passes through the metal sintered mesh 10 and enters the cylinder of the first resin adsorption tower T1 to contact the resin. Resin with good adsorption and desorption effects and strong regenerability is adopted, and under the action of van der Waals force, organic substances are adsorbed into the pores of the resin. The tail gas passes through the resin filling layer from bottom to top, and the VOCs content in the tail gas gradually decreases, and finally decreases to 30 mg / m³ and below. Then, it enters the tail gas outlet pipe through the tail gas outlet valve V2 at the center of the top of the first resin adsorption tower T1, and then enters the discharge fan F3 and is discharged into the atmosphere through the discharge pipe G5. A VOCs detector is installed on the inlet pipe of the discharge fan F3 to online monitor whether the VOCs in the adsorbed tail gas reach the emission standard.

[0044] After about 10 hours, the VOCs detector installed on the inlet air duct of the exhaust fan F3 shows that the VOCs content in the exhaust gas exceeds the standard, and the resin in the resin adsorption tower T1 is saturated. The pneumatic valve at the outlet of the exhaust gas fan F1 is switched to the resin adsorption tower T2. At this time, the resin adsorption tower T2 enters the adsorption process, and the resin adsorption tower T1 enters the desorption process.

[0045] When the resin adsorption tower T1 is desorbed, the steam from the steam pipeline G4 first enters the resin adsorption tower T1 from the top through the steam valve V3 to contact the resin, so that the adsorbed VOCs in the resin are precipitated and the resin is regenerated.

[0046] The desorbed saturated vapor is discharged from the bottom of the resin adsorption tower T1, passes through the desorption outlet valve V7 and the desorption outlet pipe G10, and enters the condenser E1. In the condenser E1, it exchanges heat with the 32°C circulating cooling water from the circulating water inlet pipe G8. After heat exchange, the gas phase outlet temperature of the condenser E1 drops to 37°C, and the condensate is discharged through the solvent condensate collection pipe G7 and enters the leaching workshop condensate system. The cooling water temperature rises to 37°C and returns to the cooling tower from the circulating water outlet pipe G9 for circulating cooling.

[0047] A VOCs detector is installed on the desorption exhaust pipe of the resin adsorption tower T1 to display the VOCs content in the desorbed steam, so as to judge whether the resin desorption is completed.

[0048] After the steam desorption is completed, the hot air generated by the drying and cooling equipment is discharged through the DC hot air pipe G3, passes through the hot air valve V5 and the induced draft fan F2, and is introduced into the resin adsorption tower T1 to cool the resin therein. The DC hot air is discharged from the bottom of the resin adsorption tower T1 and also enters the condenser E1 to exchange heat with the circulating cooling water. After heat exchange, the uncondensed gas is discharged through the condenser exhaust pipe G6, and the condensate enters the leaching workshop condensate system through the solvent condensate collection pipe G7.

[0049] Subsequently, the switch valve at the inlet of the induced draft fan F2 is switched to the cold air inlet, that is, the hot air valve V5 is closed, the cold air valve V4 is opened, the cold air enters the induced draft fan F2 through the cold air inlet pipe G2 and the cold air valve V4, and enters the resin adsorption tower T1 through the induced draft fan F2 and the desorption air valve V6 to further cool the resin in the resin adsorption tower T1. After the cold air is discharged from the bottom of the resin adsorption tower T1, it also enters the condenser E1 through the desorption outlet pipe G10 to exchange heat with the circulating cooling water. After heat exchange, the uncondensed gas is discharged through the condenser exhaust pipe G6, and the condensate enters the leaching workshop condensate system through the solvent condensate collection pipe G7. At this time, the resin adsorption tower T1 has completed the entire desorption process.

[0050] When the VOCs detector installed on the inlet air duct of the exhaust fan F3 alarms again, it indicates that the resin adsorption tower two T2 has been saturated. At this time, switch the resin adsorption tower one T1 to the operating state, and the resin adsorption tower two T2 enters the desorption process. The tail gas adsorption and recovery system is controlled by an automatic control system and equipped with on-line instruments for detection, and the adsorption and regeneration (desorption, drying, cooling) processes are automatically switched and alternated, so that at any time, one resin adsorption tower is in adsorption and the other resin adsorption tower is in desorption, drying and regeneration, thus ensuring the continuous operation and continuous treatment capacity of the tail gas adsorption and recovery system.

[0051] The above is only the preferred and feasible embodiment of the present invention, which shows and describes the basic principles, main features and advantages of the present invention. Therefore, the patent protection scope of the present invention is not limited thereby. Those skilled in the art should understand that the present invention is not limited by the above embodiments. Except for the above embodiments, without departing from the spirit and scope of the present invention, the present invention may have other embodiments. The present invention will also have various changes and improvements. Any technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope required by the present invention. The protection scope required by the present invention is defined by the appended claims and their equivalents. The technical features not described in the present invention can be realized by or adopted the existing technologies, and will not be elaborated herein.

Claims

1. A system for recovering solvent by adsorption of tail gas from a leaching workshop, comprising a tail gas pipe from a leaching workshop, characterized in that: The outlet of the tail gas pipe of the leaching workshop is connected to the inlet of the tail gas fan, the outlet of the tail gas fan is connected to the tail gas inlet of the lower side wall of each resin adsorption tower through the tail gas inlet valve, and the tail gas outlet at the top center of each resin adsorption tower is connected to the inlet of the exhaust fan through the tail gas outlet valve, and the outlet of the exhaust fan is connected to the exhaust pipe; A desorption steam inlet and a desorption air inlet are respectively provided at the top of each resin adsorption tower. The steam pipeline is connected to the desorption steam inlet of each resin adsorption tower through a steam valve. The outlet of the cold air inlet pipe is connected to the inlet of the induced draft fan through a cold air valve. The outlet of the DC hot air pipe is connected to the inlet of the induced draft fan through a hot air valve. The outlet of the induced draft fan is connected to the desorption air inlet at the top of each resin adsorption tower through a desorption air valve. A desorption outlet is provided at the bottom center of each resin adsorption tower, and each desorption outlet is respectively equipped with a desorption outlet valve. The outlet of each desorption outlet valve is connected to the shell side inlet of the condenser through a desorption outlet pipe, the shell side exhaust port of the condenser is connected to the condenser exhaust pipe, and the shell side liquid discharge port of the condenser is connected to the solvent condensate collection pipe.

2. The solvent adsorption and recovery system for the tail gas of the leaching workshop according to claim 1, wherein: A VOCs detector is installed on the inlet pipe of the exhaust fan.

3. The solvent adsorption and recovery system for the tail gas of the leaching workshop according to claim 1, characterized in that: A VOCs detector is also installed on the outlet side wall of the desorption outlet pipe.

4. The solvent adsorption and recovery system for the tail gas of the leaching workshop according to claim 1, wherein: The outlet of the exhaust fan is also connected to the inlet of the exhaust fan through an emergency discharge valve and a bypass air duct.

5. The solvent adsorption and recovery system for the tail gas of the leaching workshop according to claim 1, wherein: Two resin adsorption towers are provided in parallel.

6. The solvent adsorption and recovery system for the tail gas of the leaching workshop according to claim 1, wherein: The upper and lower cross sections of the inner cavity of the resin adsorption tower are respectively provided with metal sintered meshes. The adsorption resin is filled above the lower metal sintered mesh, and the upper metal sintered mesh is located above the resin layer to prevent the resin from flying out.

7. The solvent adsorption and recovery system for the tail gas of the leaching workshop according to claim 6, characterized in that: The tail gas inlet of the resin adsorption tower is located below the lower metal sintered mesh. The upper peripheral wall of the lower metal sintered mesh and the lower peripheral wall of the upper metal sintered mesh are respectively provided with temperature gauge interfaces, and the upper peripheral wall of the lower metal sintered mesh is also provided with a pressure gauge interface.

8. The system for recovering solvent by adsorption of tail gas from a leaching workshop according to claim 6, characterized in that: A manhole sight glass that can be opened and closed and used for observation is provided on the circumferential wall between the upper and lower layers of metal sintered mesh.

9. The solvent adsorption and recovery system for the tail gas of the leaching workshop according to claim 8, wherein: There are two manhole sight glasses, which are respectively close to the top and the bottom of the resin.

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