Device for collecting and treating high-concentration organic tail gas intermittently in EPS production process

Abstract

The application discloses a device for collecting and treating intermittent high-concentration organic tail gas in an EPS production process. A discharge pipe is communicated with the inlet of a washing tank through a first pipeline, the gas outlet of the washing tank is communicated with the inlet of a vacuum buffer tank through a second pipeline, the outlet of the vacuum buffer tank is communicated with the inlet of a vacuum pump through a third pipeline, the outlet of the vacuum pump is communicated with the inlet of an absorption tower through a fourth pipeline, the outlet of the absorption tower is communicated with a water seal tank through a fifth pipeline, and the water seal tank is communicated with an RTO pipeline. A pressure balance tank is arranged between the washing tank and the vacuum buffer tank, the pressure balance tank comprises a tank body and a partition plate, the partition plate is arranged in the tank body and divides the tank body into a gas chamber and a liquid seal chamber which are communicated with each other, an exhaust pipe is arranged in the liquid seal chamber, the upper end of the exhaust pipe penetrates through the top plate of the pressure balance tank and is provided with a disc-shaped buffer chamber, and an air inlet pipe is communicated with the outlet of the washing tank through a differential pressure balance pipe. The application guarantees that the pressure is within the safe range that can be borne by the equipment, and ensures safe operation.

Description

TECHNICAL FIELD

[0001] The present application relates to EPS production equipment, in particular to a device for collecting and treating intermittent high-concentration organic tail gas in the EPS production process. BACKGROUND

[0002] The production of EPS (Expandable Polystyrene) is to add styrene monomer, initiator, dispersant, water, blowing agent and other additives into the reaction kettle, and after polymerization, resin particles containing blowing agent are obtained. After washing, centrifuging, separating and drying, expandable polystyrene bead products are obtained. During the reaction process and during washing in the washing tank, organic tail gas is generated. After water washing, the organic tail gas is discharged, which affects air quality. The generation of tail gas is intermittent and high-concentration. Intermittent discharge causes unstable pressure in the washing tank, which can cause destructive damage to the atmospheric washing tank equipment. At the same time, it will bring impact to the regenerative thermal oxidation (RTO) tail gas treatment device, causing the RTO device to be unable to smoothly and effectively treat the tail gas, and in extreme cases, it can cause an explosive accident risk. If vacuum collection is used directly, it will also affect the pressure state in the washing tank, which will also cause destructive damage to the atmospheric washing tank equipment.

[0003] The Chinese utility model with the authorized publication number CN201098599Y discloses an absorption device for vacuum tail gas in the EPS production process. The vacuum tail gas pipe is connected to a white oil tank, the overflow gas pipe of the white oil tank is connected to the lower part of the absorption tower, and the top of the absorption tower is connected to an activated carbon adsorber. The utility model directly collects vacuum, and the unstable pressure can affect the reaction process. SUMMARY

[0004] The present application aims to solve the above technical problems, and provides a device for collecting and treating intermittent high-concentration organic tail gas in the EPS production process. The pressure during the collection process is stable within a limited range, and can be stably delivered to the RTO system for treatment, achieving standard emission.

[0005] The present application solves the above technical problems by adopting the following technical solutions:

[0006] The application discloses a device for collecting and treating intermittent high-concentration organic tail gas in an EPS production process, which comprises a reaction kettle, a nitrogen inlet pipe is arranged on the upper head of the reaction kettle and is communicated with a nitrogen pipe line, a discharge pipe is arranged on the lower head of the reaction kettle, the discharge pipe is communicated with the inlet of a washing tank through a first pipe line, the gas outlet of the washing tank is communicated with the inlet of a vacuum buffer tank through a second pipe line, the outlet of the vacuum buffer tank is communicated with the inlet of a vacuum pump through a third pipe line, the outlet of the vacuum pump is communicated with the inlet of an absorption tower through a fourth pipe line, the outlet of the absorption tower is communicated with a water seal tank through a fifth pipe line, and the water seal tank is communicated with an RTO pipe line; a pressure balance tank is arranged between the washing tank and the vacuum buffer tank, the pressure balance tank comprises a tank body, a partition plate, a gas inlet pipe and a gas outlet pipe, the partition plate is arranged in the tank body and divides the tank body into a gas chamber and a liquid seal chamber which are communicated with each other, the gas outlet pipe is arranged in the liquid seal chamber, the upper end of the gas outlet pipe penetrates through the top plate of the pressure balance tank and is provided with a disc-shaped buffer chamber, and the gas inlet pipe is communicated with the outlet of the washing tank through a differential pressure balance pipe.

[0007] Compared with the prior art, the application has the beneficial effects that:

[0008] By arranging the vacuum buffer tank, the vacuum and the volume of the vacuum buffer tank are utilized to absorb the high-concentration organic tail gas intermittently discharged from the reaction kettle in a very short time, and the vacuum pump is utilized to slowly and stably transport the high-concentration organic tail gas from the vacuum buffer tank to the RTO tail gas treatment device for stable treatment, and the pressure balance tank is arranged to ensure that the pressure of the normal-pressure washing tank device is within the safe range of the device and ensure the safe and stable operation of the device.

[0009] Further, the optimization scheme of the application is:

[0010] The upper end of the partition plate is spaced apart from the top plate of the pressure balance tank, and the gas chamber and the liquid seal chamber are communicated with each other through the gap.

[0011] The cross sections of the gas chamber and the liquid seal chamber are superior arc and inferior arc, respectively.

[0012] The diameter of the buffer chamber is greater than that of the gas outlet pipe.

[0013] The pressure range of the pressure balance tank is -5 kPa to 15 kPa.

[0014] The lower end of the gas outlet pipe is below the liquid level of the liquid seal chamber.

[0015] The tank wall of the liquid seal chamber is sequentially provided with an upper liquid level meter pipe, a lower liquid level meter pipe, an overflow pipe and a liquid supplement pipe from top to bottom, the lower liquid level meter pipe is below the lower end of the gas outlet pipe, and the overflow pipe is above the lower end of the gas outlet pipe.

[0016] The liquid seal chamber is provided with a liquid seal plate, the cross section of the liquid seal plate is inverted L shape, the horizontal part of the liquid seal plate is above the overflow pipe and is fixed with the tank wall of the pressure balance tank, and the lower end of the vertical part of the liquid seal plate is below the exhaust pipe.

[0017] The absorption tower is provided with a water supplement pipeline and an online PH detector, and a circulation pipeline is installed outside the absorption tower and communicates with the upper part and the lower part of the absorption tower, and the circulation pipeline is provided with an alkali solution circulating pump.

[0018] The gas chamber, the liquid seal chamber and the buffer chamber are respectively provided with a sight glass. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a flow chart of the embodiment of the present application;

[0020] Figure 2 is a schematic diagram of the pressure balance tank of the embodiment of the present application;

[0021] Figure 3 is a top view of Figure 2 ;

[0022] Figure 4 is a sectional view of the liquid seal chamber and the exhaust pipe of the pressure balance tank of the embodiment of the present application;

[0023] Figure 5 is a structural schematic diagram of the absorption tower of the embodiment of the present application.

[0024] In the figure: reaction kettle 1; nitrogen connecting pipe 1-1; nitrogen pipeline 1-2; discharge pipe 1-3; first pipeline 2; first valve 2-1; washing tank 3; second pipeline 4; second valve 4-1; vacuum buffer tank 5; third pipeline 6; third valve 6-1; vacuum pump 7; fourth pipeline 8; fourth valve 8-1; absorption tower 9; water supplement pipeline 9-1; circulation pipeline 9-2; alkali solution circulating pump 9-3; online PH detector 9-4; fifth pipeline 10; fifth valve 10-1; water seal tank 11; sixth pipeline 12; differential pressure balance pipe 13; pressure balance tank 14; tank body 14-1; partition plate 14-2; gas chamber 14-3; liquid seal chamber 14-4; air inlet pipe 14-5; exhaust pipe 14-6; buffer chamber 14-7; lower pipe joint 14-7-1; buffer chamber body 14-7-2; upper pipe joint 14-7-3; discharge pipeline 14-7-4; upper liquid level meter pipe 14-8; overflow pipe 14-9; lower liquid level meter pipe 14-10; water inlet pipe 14-11; breather valve pipe 14-12; discharge pipe 14-13; blowdown pipe 14-14; sight glass 14-15; liquid seal plate 15; water supplement pipeline 16. DETAILED DESCRIPTION

[0025] The present application will be further described in detail below in combination with the drawings and embodiments.

[0026] Referring toFigure 1 The embodiment is a device for collecting and treating intermittent high-concentration organic tail gas in the production process of EPS, which mainly comprises a reaction kettle 1, a washing tank 3, a vacuum buffer tank 5, a vacuum pump 7, an absorption tower 9, a water seal tank 11 and a pressure balance tank 14. A stirring shaft is arranged in the reaction kettle 1, and stirring blades are arranged on the stirring shaft. The stirring shaft is driven by a speed reducer motor arranged on the upper head of the reaction kettle 1. A raw material inlet pipe is arranged on the side wall of the reaction kettle 1, and a nitrogen inlet pipe 1-1 is arranged on the top of the upper head. The nitrogen inlet pipe 1-1 is communicated with a nitrogen pipeline 1-2, and a discharge pipe 1-3 is arranged on the lower head of the reaction kettle 1.

[0027] The discharge pipe 1-3 of the reaction kettle 1 is communicated with the top inlet of the washing tank 3 through a first pipeline 2, and a first valve 2-1 is arranged on the first pipeline 2. A stirring shaft and blades are arranged in the washing tank 3, and the stirring shaft is driven by a driving motor arranged on the top of the washing tank 3. The gas outlet on the top of the washing tank 3 is communicated with the inlet on the top of the vacuum buffer tank 5 through a second pipeline 4, and a second valve 4-1 is arranged on the second pipeline 4. The outlet on the lower part of the vacuum buffer tank 5 is communicated with the inlet of the vacuum pump 7 through a third pipeline 6, and three vacuum pumps 7 are arranged in parallel. A third valve 6-1 is arranged on the third pipeline 6. The vacuum buffer tank 5 is kept in a vacuum state at ordinary times. When the tail gas comes, the tail gas is absorbed into the vacuum buffer tank 5 in a very short time, and then the tail gas is slowly and stably sent into the RTO treatment device by the vacuum pump 7.

[0028] The outlet of the vacuum pump 7 is communicated with the inlet of the bottom of the absorption tower 9 through a fourth pipeline 8. Figure 5 The absorption tower 9 has the function of adjusting the PH value of the liquid in the absorption tower 9. The absorption tower 9 is provided with a water supplement pipeline 9-1 and a liquid level meter. A circulation pipeline 9-2 is arranged outside the absorption tower 9. The two ends of the circulation pipeline 9-2 are respectively communicated with the upper part and the lower part of the absorption tower 9. An alkali solution circulation pump 9-3 is arranged on the circulation pipeline 9-2. The alkali solution circulation pump 9-3 makes the liquid in the absorption tower 9 circulate and mix. An online PH detector 9-4 is arranged on the absorption tower 9. The online PH detector 9-4 is electrically connected with a DCS system. The online PH detector 9-4 detects the PH value of the liquid in the absorption tower 9 in real time. The DCS system controls the water supplement pipeline 9-1 to deliver water and a PH regulator into the absorption tower 9 to adjust the PH value of the liquid in the absorption tower 9. The outlet on the top of the absorption tower 9 is communicated with the inlet of the water seal tank 11 through a fifth pipeline 10. The water seal tank 11 is communicated with an RTO pipeline through a sixth pipeline 12. The fourth pipeline 8 and the fifth pipeline 10 are respectively provided with a fourth valve 8-1 and a fifth valve 10-1.

[0029] A pressure balance tank 14 is arranged between the washing tank 3 and the vacuum buffer tank 5. Figure 2 , Figure 3 , Figure 4As shown in the figure, the pressure balance tank 14 is mainly composed of a tank body 14-1, a partition plate 14-2, a gas chamber 14-3, a liquid seal chamber 14-4, an air inlet pipe 14-5, an air outlet pipe 14-6 and a buffer chamber 14-7. The inner diameter of the tank body 14-1 is 1500 mm and the height is 2000 mm. The partition plate 14-2 is arranged in the tank body 14-1. The partition plate 14-2 divides the pressure balance tank 14 into the gas chamber 14-3 and the liquid seal chamber 14-4. The cross section of the gas chamber 14-3 is a superior arc bow shape and the cross section of the liquid seal chamber 14-4 is an inferior arc bow shape. The cross sectional area of the liquid seal chamber 14-4 is 0.404 square meters. A gap is left between the partition plate 14-2 and the top plate of the pressure balance tank 14. The gap is 200 mm. The gas chamber 14-3 and the liquid seal chamber 14-4 are communicated with each other through the gap. The flow cross sectional area of the gap is greater than or equal to 0.125 square meters.

[0030] The top plate above the gas chamber 14-3 is provided with the air inlet pipe 14-5. The air inlet pipe 14-5 is communicated with the air outlet of the top of the washing tank 3 through the differential pressure balance pipe 13. The liquid seal chamber 14-4 is filled with water. The air outlet pipe 14-6 is arranged in the liquid seal chamber 14-4. The specification of the air outlet pipe 14-6 is DN400. The lower end of the air outlet pipe 14-6 extends below the liquid level. The upper end of the air outlet pipe 14-6 extends out of the top plate. The upper end of the air outlet pipe 14-6 is communicated with the buffer chamber 14-7 through the connecting pipe joint 14-6-1. The buffer chamber 14-7 is communicated with the lower pipe joint 14-7-1, the disc-shaped buffer chamber body 14-7-2 and the upper pipe joint 14-7-3. The lower pipe joint 14-7-1 is communicated with the connecting pipe joint 14-6-1. The upper pipe joint 14-7-3 is communicated with the discharge pipeline 14-7-4. The bottom surface of the buffer chamber body 14-7-2 is 405 mm away from the top plate. The height of the buffer chamber body 14-7-2 is 200 mm and the diameter is 800 mm.

[0031] The tank wall above the liquid seal chamber 14-4 is provided with the upper liquid level meter pipe 14-8. The upper liquid level meter pipe 14-8 is close to the top plate. The tank wall at the liquid level is provided with the overflow pipe 14-9. The bottom surface of the inner hole of the overflow pipe 14-9 is flush with the liquid level. The tank wall below the air outlet pipe 14-6 is provided with the lower liquid level meter pipe 14-10. The center of the lower liquid level meter pipe 14-10 is 980 mm away from the bottom plate. The tank wall below the lower liquid level meter pipe 14-10 is provided with the water inlet pipe 14-11. The water inlet pipe 14-11 is communicated with the water supply pipeline 16.

[0032] The top plate of the pressure balance tank 14 is provided with a breather valve pipe 14-12, the breather valve pipe 14-12, the gas inlet pipe 14-5 and the gas outlet pipe 14-6 are arranged in an equilateral triangle. The bottom of the tank wall of the gas chamber 14-3 is provided with a discharge pipe 14-13, and the bottom of the tank wall of the liquid seal chamber 14-4 is provided with a blowdown pipe 14-14. The gas chamber 14-3, the liquid seal chamber 14-4 and the buffer chamber 14-7 are respectively provided with a sight glass 14-15. The liquid seal chamber 14-4 is provided with a liquid seal plate 15, the cross section of the liquid seal plate 15 is inverted L-shaped, the horizontal part of the liquid seal plate 15 is above the overflow pipe 14-9 and is welded with the tank wall of the pressure balance tank 14, the lower end of the vertical part of the liquid seal plate 15 is below the lower end of the gas outlet pipe 14-6, and the liquid seal plate 15 prevents the tail gas from escaping through the overflow pipe 14-9 under the condition of slight positive pressure. The material of the pressure balance tank 14 is stainless steel.

[0033] The balance pressure range of the pressure balance tank 14 is -5 kPa to 15 kPa, the pressure of the gas chamber 14-3 is -5 kPa under working condition 1, the liquid in the gas outlet pipe 14-6 is pressed into the liquid seal chamber 14-4, the liquid level in the liquid seal chamber 14-4 is raised, and the liquid level in the gas outlet pipe 14-6 is 405 mm high; the pressure of the gas chamber 14-3 is 15 kPa under working condition 2, the liquid in the liquid seal chamber 14-4 is pressed into the gas outlet pipe 14-6 and the buffer chamber 14-7, and the liquid level in the buffer chamber 14-7 is 115 mm high; when the pressure of the gas chamber 14-3 is greater than 15 kPa, the gas is discharged from the upper opening of the upper pipe section 14-7-3 and the discharge pipeline 14-7-4.

[0034] The working process is: the liquid material in the reaction kettle 1 enters the washing tank 3 from the first pipeline 2 under the action of the gas pressure (absolute pressure 200 to 300 kPa) in the reaction kettle, after the liquid material in the reaction kettle 1 is exhausted, the high-concentration gas enters the washing tank 3 within 1 to 3 minutes, the pressure signal is transmitted to the DCS system through the pressure transmitter above the washing tank 3, when the pressure in the washing tank 3 reaches 8 kPa, the second valve 4-1 on the pipeline from the washing tank 3 to the vacuum buffer tank 5 is immediately opened through the interlocking action of the DCS system, the second valve 4-1 is an interlocking cut-off valve, at this time, the pressure in the vacuum buffer tank 5 gradually rises from -90 kPa to close to 0 kPa under the vacuum state, the pressure in the reaction kettle 1 and the washing tank 3 also decreases to 0 kPa, the high-concentration organic tail gas in the vacuum buffer tank 5 is transported into the absorption tower 9 through the transport action of the vacuum pump 7, the alkali solution in the absorption tower 9 is circulated by the alkali solution circulating pump 9-3, the high-concentration organic tail gas removes the acidic impurities in the tail gas through the absorption of the alkali solution, then passes through the water seal tank 11, and finally is transported to the RTO treatment device for disposal and meets the emission standard.

[0035] When the pressure of the washing tank is higher than or equal to -5 kPa and lower than or equal to 15 kPa, the pressure balance tank 14 is kept in a balanced state, no gas enters or exits. In a special case, when the pressure in the washing tank 3 is lower than -5 kPa, due to the action of atmospheric pressure, external air breaks through the liquid surface of the exhaust pipe 14-6 of the pressure balance tank 14 into the upper part of the liquid seal chamber 14-4, and then enters the gas chamber 14-3 through the upper part of the partition plate 14-2, and then enters the washing tank 3 through the gas inlet pipe 14-5, the gas flow can reach 600 cubic / min, so that the pressure in the washing tank 3 quickly rises to between -5 kPa and 0 kPa; when the pressure in the washing tank 3 is higher than 15 kPa, due to the action of the gas pressure in the tank, the gas in the washing tank 3 communicates through the gas inlet pipe 14-5 and the upper space of the partition plate 14-2, and the water in the liquid seal chamber 14-4 is discharged to the exhaust pipe 14-6, the liquid level of the liquid seal chamber 14-4 drops, and the liquid level in the exhaust pipe 14-6 rises. When the liquid level rises to the buffer chamber 14-7, the water diffuses in the buffer chamber 14-7, and the liquid level rises very slowly. At this time, the liquid level of the liquid seal chamber 14-4 is lower than the lower end of the exhaust pipe 14-6, and the gas in the washing tank 3 is discharged to the safe zone through the exhaust pipe 14-6, and the gas flow can reach 720 cubic / min, so that the pressure in the washing tank 3 quickly decreases to below 15 kPa, and the water returns from the buffer chamber 14-7 to the liquid seal chamber 14-4. Through the above process, the pressure in the washing tank 3 is effectively protected within the safe range of -5 kPa to 15 kPa. When the liquid level in the liquid seal chamber 14-4 changes, water is supplied through the water inlet pipe 14-11 or overflowed through the overflow pipe 14-9 to keep the water level in the liquid seal chamber 14-4 within a safe range. The liquid seal plate 15 can effectively prevent high-concentration organic tail gas from escaping through the liquid flow pipe 14-9 under normal circumstances. The gas chamber 14-3 is normally free of liquid, and can temporarily collect a small amount of liquid material brought out from the gas inlet pipe 14-5 under certain conditions in the washing tank 3. The liquid is observed through the sight glass 14-15 and discharged to the recovery system through the discharge pipe 14-13 to ensure that there is no loss of material in the washing tank 3.

[0036] The above description is only the preferred embodiment of the present application, and does not limit the scope of the present application. Any equivalent structural changes made according to the content of the specification and drawings are included in the scope of the present application.

Claims

1. An apparatus for collecting and treating intermittent high-concentration organic tail gas in an EPS production process, comprising a reaction kettle, an upper head of the reaction kettle being provided with a nitrogen connection pipe in communication with a nitrogen pipeline, and a lower head of the reaction kettle being provided with a discharge pipe, characterized in that: the discharge pipe is connected to an inlet of a washing tank through a first pipeline, a gas outlet of the washing tank is connected to an inlet of a vacuum buffer tank through a second pipeline, an outlet of the vacuum buffer tank is connected to an inlet of a vacuum pump through a third pipeline, an outlet of the vacuum pump is connected to an inlet of an absorption tower through a fourth pipeline, an outlet of the absorption tower is connected to a water seal tank through a fifth pipeline, and the water seal tank is connected to an RTO pipeline; a pressure balance tank is arranged between the washing tank and the vacuum buffer tank, the pressure balance tank comprises a tank body, a partition plate, an inlet pipe and an outlet pipe, the partition plate is arranged in the tank body and divides the tank body into a gas chamber and a liquid seal chamber which are in communication with each other, the outlet pipe is arranged in the liquid seal chamber, an upper end of the outlet pipe penetrates through a top plate of the pressure balance tank and is provided with a disc-shaped buffer chamber, and the inlet pipe is connected to an outlet of the washing tank through a differential pressure balance pipe; a diameter of the buffer chamber is greater than a diameter of the outlet pipe; a lower end of the outlet pipe extends below a liquid level of the liquid seal chamber; a tank wall of the liquid seal chamber is sequentially provided, from top to bottom, with an upper liquid level meter pipe, a lower liquid level meter pipe, an overflow pipe and a liquid supplement pipe, the lower liquid level meter pipe is located below the lower end of the outlet pipe, and the overflow pipe is located above the lower end of the outlet pipe; a liquid seal plate is arranged in the liquid seal chamber, a cross section of the liquid seal plate is inverted L-shaped, a horizontal part of the liquid seal plate is located above the overflow pipe and is fixedly connected to the tank wall of the pressure balance tank, and a lower end of a vertical part of the liquid seal plate is located below the outlet pipe; a gap is left between an upper end of the partition plate and the top plate of the pressure balance tank, and the gas chamber and the liquid seal chamber are in communication with each other through the gap; cross sections of the gas chamber and the liquid seal chamber are superior arc and inferior arc, respectively; a pressure range of the pressure balance tank is -5 kPa to 15 kPa; the absorption tower is provided with a water supplement pipeline and an online PH detector, and a circulation pipeline is arranged outside the absorption tower and is in communication with upper and lower parts of the absorption tower, and the circulation pipeline is provided with an alkali solution circulation pump; the gas chamber, the liquid seal chamber, the outlet pipe and the buffer chamber are respectively provided with sight glasses. ​ ​ ​ ​ ​ ​ 2. The apparatus for collecting and treating the intermittent high-concentration organic tail gas in the EPS production process according to claim 1, characterized in that: ​ 3. The apparatus for collecting and treating the intermittent high-concentration organic tail gas in the process of producing EPS according to claim 1, characterized in that: ​ 4. The apparatus for collecting and treating the intermittent high-concentration organic tail gas in the process of producing EPS according to claim 1, characterized in that: ​ 5. The apparatus for collecting and treating the intermittent high concentration organic off-gas in the process of producing EPS according to claim 1, characterized in that: ​ 6. The apparatus for collecting and treating the intermittent high concentration organic off-gas in the process of producing EPS according to claim 1, characterized in that: ​

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