Chemical extraction tail gas recovery and VOCs treatment equipment

Abstract

The utility model discloses chemical extraction tail gas recovery and VOCs (Volatile Organic Compounds) treatment equipment which comprises a tail gas collection pipeline, a recovery tower, a circulating pump, an induced draft fan, a liquid seal and heat treatment equipment, two layers of plastic Pall ring packing are arranged in the recovery tower, a demineralized water spraying layer is arranged above the plastic Pall ring packing, a demisting device is arranged at the top of the recovery tower, and a spraying liquid storage tank is arranged at the bottom of the recovery tower. Waste gas is obtained through the tail gas collecting pipeline, spraying absorption of the waste gas is carried out through the recovery tower, and finally combustion treatment is carried out through the heat treatment equipment, so that the VOCs treatment efficiency is improved, the treatment cost can be greatly reduced, the carbon dioxide emission in the treatment process is reduced, and the effects of reducing pollution and carbon are achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of VOCs waste gas treatment equipment, in particular to a chemical extraction tail gas recovery and VOCs treatment equipment. Background Technique

[0002] Chemical extraction is a method of transferring solute substances from one solvent to another by utilizing the differences in solubility or distribution coefficients of substances in two immiscible or slightly miscible solvents.

[0003] There are two aspects to the common extraction processes and VOCs waste gas treatment technologies. One is the destruction technology, including direct combustion method, catalytic combustion method, biological oxidation method, etc. The other is the recovery technology, including adsorption method, condensation method, membrane separation method, etc. Due to the complexity of VOCs pollution emissions, in most cases, using a single treatment technology often fails to meet the treatment requirements and is also economically unreasonable. Therefore, the use of a multi-technology combination treatment method is a relatively common strategy at present. Considering the characteristics of various VOCs treatment processes and the specific situation of the waste gas, most current waste gas VOCs treatment technologies adopt the adsorption method or the activated carbon adsorption process alone. The main technical problems are high cost, low treatment efficiency, secondary pollution, etc. Content of the Utility Model

[0004] To solve the above technical problems, the utility model provides. To have a basic understanding of some aspects of the disclosed embodiments, a simple summary is given below. This summary part is not a general review, nor is it intended to identify key / important constituent elements or delineate the protection scope of these embodiments. Its sole purpose is to present some concepts in a simple form as a preamble to the subsequent detailed description.

[0005] The utility model adopts the following technical solutions:

[0006] Provide a chemical extraction tail gas recovery and VOCs treatment equipment, including: tail gas collection pipeline, recovery tower, induced draft fan, liquid seal and heat treatment equipment;

[0007] The tail gas collection pipeline is connected to the tail gas discharge port of the extraction tank, the air inlet of the recovery tower is connected to the tail gas collection pipeline, the air inlet of the induced draft fan is connected to the air outlet of the recovery tower, the liquid seal is connected to the air outlet of the induced draft fan, and the heat treatment equipment is arranged on the outlet side of the liquid seal;

[0008] Two layers of plastic Pall rings are arranged in the recovery tower, a desalted water spray layer is arranged above the plastic Pall rings, a demisting device is arranged at the top of the recovery tower, and a spray liquid storage tank is arranged at the bottom of the recovery tower.

[0009] Further, the chemical extraction tail gas recovery and VOCs treatment equipment further includes: a manual valve for adjusting the pipeline negative pressure; the manual valve is arranged at the position where the tail gas collection pipeline is connected to the tail gas discharge port.

[0010] Further, the chemical extraction tail gas recovery and VOCs treatment equipment further includes: a condensate recovery pipeline; the tail gas collection pipeline is arranged from high to low starting from the connection with the tail gas discharge port, the slope is set to be not less than 0.005, and the condensate recovery pipeline is arranged at the lowest point, and the condensate recovery pipeline is connected to the spray liquid storage tank.

[0011] Further, the chemical extraction tail gas recovery and VOCs treatment equipment further includes: a total recovery pipeline; the condensate recovery pipeline and the spray liquid storage tank are connected to the total recovery pipeline.

[0012] Further, 1-9 uniformly distributed centrifugal atomizing nozzles are arranged in the desalted water spray layer, and the pressure at the nozzle of the centrifugal atomizing nozzle is ≥0.1MPa.

[0013] Further, the chemical extraction tail gas recovery and VOCs treatment equipment further includes: a circulation pump; the liquid inlet of the circulation pump is connected to the spray liquid storage tank, and the liquid outlet of the circulation pump is connected to the centrifugal atomizing nozzle.

[0014] Further, the height of the plastic Pall ring packing is 0.5-1.0m.

[0015] Further, the height of the demisting device is 500mm, and the demisting device is a baffle or wire mesh demister.

[0016] Further, the chemical extraction tail gas recovery and VOCs treatment equipment further includes: a water replenishing valve, a liquid level alarm interlock instrument and a liquid discharge valve arranged on the spray liquid storage tank.

[0017] Further, the heat treatment equipment is a boiler or a kiln.

[0018] The beneficial effects brought by the present utility model: The waste gas is obtained by using the tail gas collection pipeline, and the waste gas is spray-absorbed through the recovery tower, and finally the heat treatment equipment is used for combustion treatment, so as to improve the VOCs treatment efficiency, greatly reduce the treatment cost, reduce the carbon dioxide emission amount in the treatment process, and achieve the effect of reducing pollution and carbon emission. Description of the Drawings

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. 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.

[0020] Figure 1 is a schematic diagram of an equipment for chemical extraction tail gas recovery and VOCs treatment of the present invention;

[0021] Figure 2 is a structural schematic diagram of the recovery tower of the present invention;

[0022] Figure 3 is a flow chart of the extraction process of essence and flavor. Detailed implementation manners

[0023] The following will describe the embodiments of the present invention in detail with reference to the drawings. It should be clear that the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0024] For various processes adopted in VOCs treatment, the characteristics of the waste gas source generally have an impact on the selection of the applicability of the treatment equipment. Therefore, when selecting a treatment process, it is necessary to first evaluate the characteristics of the pollution source, such as the substance composition, air volume, and concentration, and then evaluate the equipment stability, safety, initial cost, operating cost, etc. The following table shows the applicable ranges, advantages, and disadvantages of different treatment technologies:

[0025]

[0026] As shown in the above table, considering the characteristics of various VOCs treatment processes and the specific situation of the waste gas, currently most waste gas VOCs treatment technologies adopt the adsorption method or the activated carbon adsorption process alone. The main problems of this method are high cost, low treatment efficiency, secondary pollution, etc. To address this issue, as Figure 1-2 shown, this embodiment provides an equipment for chemical extraction tail gas recovery and VOCs treatment, which is used to treat the waste gas generated during the chemical extraction process, and is particularly suitable for enterprises with a small amount of waste gas. These enterprises usually have heat treatment equipment such as boilers or kilns that operate synchronously with production.

[0027] The equipment for chemical extraction tail gas recovery and VOCs treatment in this embodiment includes: a tail gas collection pipeline 1, a manual valve 2, a condensate recovery pipeline 3, a total recovery pipeline 4, a recovery tower 5, a circulation pump 6, an induced draft fan 7, a liquid seal 8, and a heat treatment equipment 9.

[0028] The tail gas collection pipeline 1 is connected to the tail gas discharge port 10 of the extraction tank. Starting from the connection with the tail gas discharge port 10, the tail gas collection pipeline 1 is arranged from high to low, and the slope is set to be not less than 0.005. A condensate recovery pipeline 3 is provided at the lowest point of the tail gas collection pipeline 1, and the condensate recovery pipeline 3 is connected to the total recovery pipeline 4.

[0029] The tail gas collection pipeline 1 is arranged from high to low starting from the connection with the discharge port 10, and it is ensured that the slope of the entire pipeline is not less than 0.005 (that is, at least 5 mm drops per meter of pipeline length). The slope design enables the waste gas and the condensate that may be carried in it to flow naturally downward, reducing the need for additional power equipment, thereby saving energy consumption and reducing operating costs. Moreover, by providing a condensate recovery pipeline 3 at the lowest point of the tail gas collection pipeline 1, the condensate in the pipeline can be effectively collected and guided to the total recovery pipeline 4. The liquid collected by the total recovery pipeline 4 is used for further chemical product separation and purification and solvent recovery treatment. The above structural design helps to prevent problems such as pressure fluctuations or blockages caused by liquid accumulation inside the pipeline, reduce the deposits inside the pipeline, ensure the stable operation of the system, and at the same time achieve resource recovery and utilization, avoiding environmental pollution caused by direct discharge.

[0030] A manual valve 2 is provided at the position where the tail gas collection pipeline 1 is connected to the tail gas discharge port 10. The manual valve 2 is mainly used to adjust the negative pressure inside the pipeline to ensure that the pressure at the connection of the tail gas collection pipeline 1 and the tail gas discharge port 10 is about -100 Pa, so as to maintain the balance of the air volume. Specifically, the manual valve 2 can control the air flow rate entering the pipeline through the opening and closing degree, thereby adjusting the negative pressure inside the pipeline. Maintaining the air volume balance helps to optimize the air flow distribution of the entire system, reduce unnecessary energy consumption, and ensure that all tail gases can be effectively collected and treated.

[0031] Two layers of plastic Pall rings 501 are provided inside the recovery tower 5, and a layer of desalted water spray layer 502 is provided above each layer of plastic Pall rings 501. A demisting device 503 is provided at the top of the recovery tower, and a spray liquid storage tank 504 is provided at the bottom of the recovery tower.

[0032] The recovery tower 5 adopts the method of spray absorption, and the spray liquid is desalted water. Two layers of desalted water spray layers 502 are provided inside the recovery tower 5, and 1 - 9 evenly distributed centrifugal atomizing nozzles 505 are provided inside each desalted water spray layer 502 to ensure that the spray liquid can evenly cover the surface of the packing, improving the uniformity and efficiency of the absorption process. The pressure at the nozzle of the centrifugal atomizing nozzle 505 ≥ 0.1 MPa to form fine liquid droplets, increasing the liquid-gas contact area and improving the absorption rate and efficiency.

[0033] The height of the plastic Pall ring packing 501 is 0.5 - 1.0 m. These packings provide the VOCs in the waste gas with an opportunity to fully contact the spraying liquid. By passing through two layers of plastic Pall ring packing 501, the contact area between the gas and the liquid is increased, the absorption efficiency of VOCs is improved, the harmful components in the waste gas can be removed more effectively, and the pollutants discharged into the atmosphere can be reduced.

[0034] The height of the demister 503 is 500 mm. The demister 503 is a baffle or wire mesh demister, which is used to remove the liquid droplets entrained in the tail gas and prevent the liquid droplets from being discharged into the atmosphere.

[0035] The spraying liquid storage tank 504 is used to collect the liquid after spraying, and the recycling of the spraying liquid can be realized through the circulation pump 6. Specifically, the liquid inlet of the circulation pump 6 is connected to the spraying liquid storage tank 504, and the liquid outlet of the circulation pump 6 is connected to the centrifugal atomizing nozzle 505. The liquid after spraying falls into the spraying liquid storage tank 504 at the bottom of the recovery tower 5. The circulation pump 6 sucks up the spraying liquid in the spraying liquid storage tank 504, and then sends it back to the desalted water spraying layer 502 in the recovery tower 5 through the liquid outlet, and is sprayed out by the centrifugal atomizing nozzle 505 to participate in the next round of absorption process.

[0036] A water replenishing valve, a liquid level alarm interlock instrument and a liquid discharging valve are arranged on the spraying liquid storage tank 504. The spraying liquid storage tank 504 is connected to the total recovery pipeline 4. The liquid level alarm interlock instrument is a special instrument for monitoring the liquid level of the liquid or slurry in the container or storage tank, and triggering an alarm and automatically controlling the relevant instruments when the liquid level reaches the predetermined high limit value and low limit value. In this embodiment, the instruments to be controlled are the water replenishing valve and the liquid discharging valve. When the liquid level is high, the liquid discharging valve is opened to discharge the excess spraying liquid into the total recovery pipeline 4 for further chemical product separation and purification and solvent recovery treatment together with the condensate water; when the liquid level is low, the water replenishing valve is automatically opened to supplement a certain amount of desalted water to ensure the liquid level stability.

[0037] The air inlet of the recovery tower 5 is connected to the tail gas collection pipeline 1, the air inlet of the induced draft fan 7 is connected to the air outlet of the recovery tower 5, the liquid seal 8 is connected to the air outlet of the induced draft fan 7, and the heat treatment equipment 9 is arranged on the outlet side of the liquid seal 8; the heat treatment equipment 9 is a boiler or a kiln.

[0038] After the chemical extraction tail gas is collected by the tail gas collection pipeline 1, it enters the recovery tower 5. Demineralized water is used to pressurize the spray liquid through the circulation pump 6, and the spray liquid is atomized through the centrifugal atomizing nozzle 505 to increase the contact probability between the spray liquid droplets and the tail gas. After the tail gas is absorbed by spraying, the chemical products and solvents enter the spray liquid. After the tail gas is absorbed by the spray liquid, it enters the demister of the recovery tower 1, and most of the collected tail gas is collected back into the spray liquid storage tank 504 of the recovery tower 1. The VOCs-containing waste gas after spray recovery is pressurized and transported by the induced draft fan 7 into the liquid seal 3. After passing through the safety water seal, it enters the air inlet of the heat treatment equipment 9. The tail gas after combustion in the boiler or furnace enters the flue gas denitrification, desulfurization and dust removal system and is finally discharged to the chimney.

[0039] The chemical extraction tail gas recovery and VOCs treatment equipment of this embodiment pre-recovers the products and solvents of the extraction process, uses the method of burning in heat treatment equipment such as boilers or furnaces to improve the VOCs treatment efficiency, can greatly reduce the treatment cost, reduce the carbon dioxide emissions during the treatment process, and achieve the effect of reducing pollution and carbon emissions.

[0040] The following is an example to illustrate the treatment process:

[0041] Such as Figure 3 shown, an extraction process of essence and flavor, with a total of 3 extraction tanks, each extraction tank having a volume of 20m 3 , using 75% ethanol for extraction. Before extraction, the raw materials need to be steamed with steam at 180°C, and the steam comes from a 3t / h natural gas boiler.

[0042] The tail gas discharge ports of the 3 extraction tanks are respectively connected to the tail gas collection pipeline. A manual valve is set between the tail gas discharge port of each extraction tank and the tail gas collection pipeline. The pressure at the tail gas discharge port of the extraction tank is about -100Pa, and each extraction tank is designed to handle about 500m 3 / h, and the total treatment volume of the extraction tail gas is about 1500m 3 / h. The tail gas collection pipeline uses a PVC pipeline with a diameter of 200mm, is arranged from high to low, and the slope is set at about 0.05. A condensate recovery pipeline is set at the lowest point before the tail gas collection pipeline enters the recovery tower 5 and is connected to the spray liquid storage tank at the bottom of the recovery tower 5, so that the condensate of the tail gas collection pipeline enters the spray liquid storage tank.

[0043] The recovery tower 5 adopts a PVC structure, with a tower height of 5.5m and an inner diameter of 800mm. There are a total of two demineralized water spray layers, each layer with a height of 2m, and 3 centrifugal atomizing nozzles are arranged on each layer. Plastic Pall rings with a diameter of 500mm are arranged 800mm below the nozzles. Demineralized water is used as the spray liquid, and 2 circulation pumps 6 are arranged, 1 for standby and 1 for use. The flow rate of each pump is 6m 3 / h, with a head of 15 m. The bottom of the recovery tower 5 is a spray liquid storage tank, which is equipped with a liquid level alarm interlock instrument. When the liquid level is high, the drain valve is opened to discharge the excess spray liquid into the total recovery pipeline for further chemical product separation, purification and solvent recovery treatment together with the condensate water; when the liquid level is low, the makeup water valve is automatically opened to supplement a certain amount of demineralized water to ensure the liquid level is stable. A baffle demister is arranged at the top of the recovery tower 5, and the height of the demister is 500 mm. An ethanol concentration alarm instrument is installed at the outlet of the recovery tower.

[0044] The VOCs-containing waste gas after spray recovery is pressurized and transported by the induced draft fan 7. After passing through a safety water seal and an electric valve, it enters the combustion air inlet of a 3t / h natural gas boiler. At the same time, a reflux device is arranged below the induced draft fan 7 to return the condensate water of the induced draft fan to the spray liquid storage tank. After the VOCs-containing waste gas is burned in the boiler, the flue gas is discharged through the chimney.

[0045] Using the chemical extraction tail gas recovery and VOCs treatment equipment proposed in this application, the average ethanol concentration in the tail gas collected by the extraction tank is 1800 mg / m 3 , and the average concentration of total non-methane hydrocarbons is 720 mg / m 3 ; after recovery, the average ethanol concentration in the waste gas at the outlet of the recovery tower is 429 mg / m 3 , and the average concentration of total non-methane hydrocarbons is 210 mg / m 3 . When the waste gas enters the natural gas boiler for combustion, the emission concentration of total non-methane hydrocarbons is lower than 1 mg / m 3 , and the ethanol emission concentration is 0.63 mg / m 3 . The extraction tail gas enters the natural gas boiler as combustion-supporting air after recovery pretreatment, and the VOCs are burned and treated under the high-temperature conditions of the boiler, so that the VOCs pollutants can be efficiently treated.

[0046] In summary, this application pre-treats and recovers the products and solvents of the extraction process, uses the combustion method of heat treatment equipment such as boilers or kilns to improve the VOCs treatment efficiency, can greatly reduce the treatment cost, reduce the carbon dioxide emissions during the treatment process, and achieve the effect of reducing pollution and carbon emissions.

[0047] The above is only the specific implementation manner of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present utility model should be covered by the protection scope of the present utility model. Therefore, the protection scope of the present utility model should be subject to the protection scope of the claims.

Claims

1. A chemical extraction tail gas recovery and VOCs treatment equipment, characterized in that: include: Tail gas collection pipeline, recovery tower, induced draft fan, liquid seal and heat treatment equipment; The tail gas collection pipeline is connected to the tail gas discharge port of the extraction tank, the air inlet of the recovery tower is connected to the tail gas collection pipeline, the air inlet of the induced draft fan is connected to the air outlet of the recovery tower, the liquid seal is connected to the air outlet of the induced draft fan, and the heat treatment equipment is arranged on the outlet side of the liquid seal; Two layers of plastic ball ring fillers are arranged in the recovery tower, a desalted water spray layer is arranged above the plastic ball ring fillers, a demisting device is arranged at the top of the recovery tower, and a spray liquid storage tank is arranged at the bottom of the recovery tower.

2. A chemical extraction tail gas recovery and VOCs treatment equipment according to claim 1, characterized in that: Also includes: A manual valve for adjusting the negative pressure of the pipeline; the manual valve is arranged at the position where the exhaust gas collection pipeline is connected to the exhaust gas discharge port.

3. A chemical extraction tail gas recovery and VOCs treatment equipment according to claim 2, characterized in that: Also includes: Condensate recovery pipeline; The exhaust gas collection pipeline is arranged from high to low starting from the connection with the exhaust gas discharge port, with a slope of not less than 0.005, and the condensate recovery pipeline is arranged at the lowest point, and the condensate recovery pipeline is connected to the spray liquid storage tank.

4. A chemical extraction tail gas recovery and VOCs treatment equipment according to claim 3, characterized in that: Also includes: A total recovery pipeline; the condensate recovery pipeline and the spray liquid storage tank are connected to the total recovery pipeline.

5. A chemical extraction tail gas recovery and VOCs treatment equipment according to claim 4, characterized in that: 1-9 evenly distributed centrifugal atomizing nozzles are arranged in the desalted water spraying layer, and the pressure at the nozzle of the centrifugal atomizing nozzle is ≥0.1MPa.

6. A chemical extraction tail gas recovery and VOCs treatment equipment according to claim 5, characterized in that: Also includes: Circulation pump; The liquid inlet of the circulation pump is connected to the spray liquid storage tank, and the liquid outlet of the circulation pump is connected to the centrifugal atomizing nozzle.

7. A chemical extraction tail gas recovery and VOCs treatment equipment according to claim 6, characterized in that: The height of the plastic ball ring packing is 0.5-1.0m.

8. The chemical extraction tail gas recovery and VOCs treatment equipment according to claim 7 is characterized in that: The height of the demister is 500 mm, and the demister is a baffle or a wire mesh demister.

9. The chemical extraction tail gas recovery and VOCs treatment equipment according to claim 8, characterized in that: Also includes: A water replenishment valve, a liquid level alarm interlocking instrument and a drain valve are arranged on the spray liquid storage tank.

10. A chemical extraction tail gas recovery and VOCs treatment equipment according to claim 9, characterized in that: The heat treatment equipment is a boiler or a kiln.

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