A furaldehyde device slagging tail gas treatment device and a slagging tail gas treatment method

Abstract

The application discloses a kind of furaldehyde device slag tail gas treatment device, including steam residue separator, absorption tower, flash tower and filter press, the feed end of steam residue separator is connected with the slag end of hydrolysis kettle, the gas discharge end of steam residue separator is connected with the gas inlet end of absorption tower by scrubber, the exhaust end of absorption tower is connected with the input end of first gas-liquid separation tank by first condenser, the bottom of absorption tower is equipped with bottom storage tank, the first liquid outlet end of absorption tower bottom storage tank is connected with the top liquid inlet end of absorption tower by circulating main pump, the second liquid outlet end of absorption tower bottom storage tank is connected with the upper end liquid inlet end of absorption tower by flash tower, circulating auxiliary pump, cooler;The third liquid outlet end of absorption tower is connected with the input end of filter press by filter press pump.The application further discloses a kind of slag tail gas treatment methods, the device of the application uses steam residue separator, absorption tower, flash tower, filter press and other equipment, saves the investment of huge environmental protection equipment facilities construction, saves high operating and maintenance cost.

Description

Technical Field

[0001] This invention belongs to the field of biomass utilization technology, specifically relating to a furfural plant slag exhaust gas treatment device and a slag exhaust gas treatment method. Background Technology

[0002] Furfural is an organic compound with the chemical formula C5H4O2. It is a colorless, transparent, oily liquid with a distinctive odor similar to benzaldehyde. It is mainly used as an industrial solvent and can also be used to produce furfuryl alcohol, furoic acid, tetrahydrofuran, γ-valerolactone, pyrrole, tetrahydropyrrole, etc.

[0003] The raw materials for furfural production are mainly agricultural waste such as corn cobs and rice husks. After pretreatment such as drying and crushing, furfural products are obtained through processes such as hydrolysis extraction under acid and distillation separation. The process mainly includes raw material preparation, hydrolysis extraction, and furfural refining. The aldehyde vapor generated by the hydrolysis reaction is condensed to form a stock solution, which is then concentrated to produce crude furfural. Crude furfural contains components such as water, methanol, acetone, formic acid, acetic acid, and 5-methylfurfural. Through initial distillation, removal of light components, neutralization and deacidification, dehydration, and refining, high-quality furfural products are obtained. Energy conservation and environmental protection factors must also be considered during the production process to ensure sustainable development.

[0004] In the existing process, the tail gas treatment method in furfural production is as follows: After hydrolysis, the pressure in the hydrolysis reactor is reduced to 0.2-0.5 MPa, the bottom discharge valve is opened, and the solid material is discharged to the slag room under gas pressure for steam-slag separation. The separated slag is conveyed to the boiler for use as fuel, and the separated gas is stored in the gas collection chamber. Then, the gas undergoes a series of treatments such as condensation, alkali washing, water washing, and dehumidification. Finally, it is extracted by an induced draft fan and sent to activated carbon adsorption and photocatalytic decomposition treatment before being discharged at a high level through the chimney.

[0005] Problems with existing processes:

[0006] 1) Large investment: It requires the construction of a slag house with a capacity of several thousand cubic meters as a gas-slag separation chamber, as well as exhaust gas treatment facilities.

[0007] 2) High difficulty in sealing the slag room: When slag is discharged, a large amount of gas will leak due to the positive pressure inside the slag room, causing environmental pollution.

[0008] 3) High difficulty in exhaust gas treatment: Because the slag discharge is intermittent, the pressure inside the slag chamber will fluctuate. When the pressure is high, the gas inside the chamber will leak outward, and when the pressure is low, external air will enter, which will increase the difficulty of treatment.

[0009] 4) Environmental protection facilities have complex processes, many pieces of equipment, large investments, and high maintenance costs.

[0010] 5) Poor performance: In the entire furfural production unit, the exhaust gas from the slag room accounts for 90% of the emissions. The composition is complex and the treatment is difficult. Currently used methods such as activated carbon adsorption and photocatalytic decomposition cannot meet the process requirements. Summary of the Invention

[0011] The purpose of this invention is to overcome the above-mentioned problems. To solve these technical problems, this invention provides the following technical solution:

[0012] The first aspect of the present invention is to provide a slag and tail gas treatment device for a furfural plant, comprising a steam-slag separator (1), an absorption tower (6), a flash evaporator (8), a first gas-liquid separator (10), and a filter press (15). The feed end of the steam-slag separator (1) is connected to the slag discharge end of the hydrolysis reactor, and the gas discharge end of the steam-slag separator (1) is connected to the gas inlet end of the absorption tower (6) via a steam scrubber (4). The exhaust end of the absorption tower (6) is connected to the input end of the first gas-liquid separator (10) via a first condenser (16), and the gas output end of the first gas-liquid separator (10) is connected to a tail gas treatment system via a blower (7). The bottom of the absorption tower (6) is provided with a bottom storage tank, and the liquid output end of the first gas-liquid separator (10) is connected to the bottom storage tank of the absorption tower (6). The first liquid outlet end of the bottom storage tank of the absorption tower (6) is connected to the absorption tower (6) via a circulating main pump (12). The upper liquid inlet of the absorption tower (6) is connected to the lower liquid inlet of the flash tower (8). The third liquid outlet of the bottom storage tank of the absorption tower (6) is connected to the input end of the filter press (15) through the filter press pump (14). The fourth liquid outlet of the bottom storage tank of the absorption tower (6) is connected to the liquid inlet of the steam scrubber (4) through the washing water pump (5). The bottom storage tank of the absorption tower (6) is provided with a sampling port (23) on its side wall. The exhaust end of the flash tower (8) is connected to the vacuum system through the second condenser (9) and the second gas-liquid separator. The lower liquid outlet of the flash tower (8) is connected to the upper liquid inlet of the absorption tower (6) and the upper liquid inlet of the flash tower (8) through the circulating auxiliary pump (13) and the cooler (11).

[0013] Preferably, the bottom of the gas-slag separator (1) is provided with a screw conveyor (2), and the screw conveyor (2) is provided with a cooling device.

[0014] Preferably, a washing water pump (5) is provided between the steam scrubber (4) and the absorption tower (6). The input end of the washing water pump (5) is connected to the fourth liquid outlet of the bottom storage tank of the absorption tower (6), the output end of the washing water pump (5) is connected to the liquid inlet of the steam scrubber (4), and the outlet end of the steam scrubber (4) is connected to the bottom storage tank of the absorption tower (6). The steam scrubber (4) has a venturi structure and includes a converging tube, a throat tube, a diverging tube, and a dehydrator connected in sequence.

[0015] Preferably, the filter press (15) is connected to both a water regulating valve (21) and a water discharge regulating valve (22) at its discharge end, and the other end of the water regulating valve (21) is connected to the bottom storage tank of the absorption tower (6).

[0016] Preferably, a circulating main pump (12) is provided on one side of the absorption tower (6), the input end of the circulating main pump (12) is connected to the first liquid outlet end of the bottom storage tank of the absorption tower (6), a liquid phase distributor is provided at the top of the absorption tower (6), and the output end of the circulating main pump (12) is connected to the liquid phase distributor at the top of the absorption tower (6).

[0017] The internal packing of the absorption tower (6) is grid packing or packing with the same structure and performance as the grid.

[0018] Preferably, a flash tower (8) and a second gas-liquid separator (17) are provided on one side of the absorption tower (6). The first liquid inlet of the flash tower (8) is connected to the second liquid outlet of the bottom storage tank of the absorption tower (6) through a pipeline. The gas outlet of the flash tower (8) is connected to the second gas-liquid separator (17) through a second condenser (9). The gas outlet of the second gas-liquid separator (17) is connected to the vacuum system through a vacuum regulating valve (19). The liquid outlet of the second gas-liquid separator (17) is connected to a water-aldehyde separator.

[0019] Preferably, the flash tower (8) is also connected to a circulating auxiliary pump (13), a cooler (11), and a reflux valve (20). The input end of the circulating auxiliary pump (13) is connected to the liquid outlet end of the flash tower (8), and the output end of the circulating auxiliary pump (13) is connected to the input end of the cooler (11). The output end of the cooler (11) is simultaneously connected to the input end of the reflux valve (20) and the liquid phase distributor at the top of the absorption tower (6). The output end of the reflux valve (20) is connected to the upper end of the flash tower (8). The flash tower (8) is also connected to a reboiler (18). The input end of the reboiler (18) is connected to the liquid outlet end of the flash tower (8), and the output end of the reboiler (18) is connected to the second liquid inlet end of the reboiler of the flash tower (8). The internal packing of the flash tower (8) is grid packing or packing with the same structure and performance as the grid. There is a liquid phase distributor at the top of the flash tower (8). When the sampling port (23) of the bottom storage tank of the absorption tower (6) detects that the furfural mass content in the liquid phase reaches 0.5% to 5%, the vacuum regulating valve (19) is opened to put the flash tower (8) into operation and control the pressure at -0.05MPa to -0.01MPa.

[0020] A second aspect of the present invention provides a method for treating exhaust gas from a furfural-based slag discharge unit, comprising:

[0021] Step S1: After hydrolysis in the hydrolysis vessel is complete, reduce the pressure in the hydrolysis vessel to 0.06–0.5 MPa and start the hydrolysis process.

[0022] The bottom discharge valve of the reactor discharges solid material into the steam-slag separator (1) under the pressure of gas. The solid material in the steam-slag separator (1) is separated into steam and slag under a pressure of -0.001MPa to 0.1MPa. The gas separated by the steam-slag separator (1) is discharged from the top of the steam-slag separator (1), washed by the steam scrubber (4), and then transported to the absorption tower (6).

[0023] Step S2: The gas from the gas scrubber (4) enters the absorption tower (6) from the bottom and comes into countercurrent contact with the spray water at the top of the absorption tower (6). Most of the gas is absorbed by the spray water, and a small amount of non-condensable gas is discharged from the top of the absorption tower (6). After being condensed by the first condenser (16) and separated by the first gas-liquid separator (10), the non-condensable gas is sent to the tail gas treatment system by the induced draft fan (7) for treatment. The condensate in the first gas-liquid separator (10) flows back to the storage tank at the bottom of the absorption tower (6).

[0024] Step S3: The slag entrained in the gas from the gas scrubber (4) is removed after being washed by the spray water in the absorption tower (6). When the slag content washed down from the spray water reaches a certain level (solid content 0.1% to 3%), it is pressurized by the filter press pump (14) and transported to the filter press (15) to remove the slag from the spray water. The slag is used as biofuel in the boiler, and the purified water is returned to the bottom storage tank of the absorption tower (6) for recycling. When the liquid level in the bottom storage tank of the absorption tower (6) is high, the water discharge regulating valve (22) is opened to send the water to the sewage treatment plant.

[0025] Preferably, in step S1: the slag separated by the steam slag separator (1) is discharged through the bottom screw conveyor (2) of the steam slag separator (1), the screw conveyor (2) is equipped with a cooling device, and then is sent to the boiler by the belt conveyor (3) for use as fuel;

[0026] In step S2: the water in the storage tank at the bottom of the absorption tower (6) is pressurized by the circulating main pump (12) and then sprayed out evenly through the liquid phase distributor at the top of the absorption tower (6);

[0027] In step S3: When the liquid level in the bottom storage tank of the absorption tower (6) is high, close the water regulating valve (21) and open the water discharge regulating valve (22) to discharge the excess water to the sewage treatment plant.

[0028] Preferably, step S4 is also included:

[0029] Step S4: Water vapor, methanol vapor, acetone vapor, and furfural vapor entrained in the gas from the steam scrubber (4) are washed and absorbed by the spray water in the absorption tower (6). The temperature of the spray water will rise, and it will be pressurized by the circulating auxiliary pump (13), cooled by the cooler (11), and then returned to the absorption tower (6) for recycling. After the furfural and other components in the spray water reach a concentration of 0.5% to 5% by the sampling port (23) of the absorption tower (6), the flash tower (8) is put into operation. The vacuum regulating valve (19) and the reflux valve (20) are opened, and the mixture of furfural, vapor, methanol, acetone and other components is flashed out at a pressure of -0.05 to -0.01 MPa. The flash vapor is discharged from the exhaust end of the flash tower (8), condensed by the second condenser (9), and enters the second gas-liquid separator (17). The uncondensed vapor after separation is transported to the vacuum system through the vacuum regulating valve (19), and the condensate is separated in the water-aldehyde separator.

[0030] Compared with the prior art, the technical effects of the present invention are as follows:

[0031] 1. This invention eliminates facilities such as the gas-slag separation chamber in traditional processes and adopts equipment such as gas-slag separators and absorption towers; slag discharge uses a screw conveyor, which has its own cooling device, which can cool the slag while conveying it, and can also prevent gas leakage from the gas-slag separator, reducing environmental pollution.

[0032] 2. This invention saves on the huge investment required for the construction of environmental protection equipment and facilities, and also saves on high operating and maintenance costs.

[0033] cost.

[0034] 3. This invention can achieve complete absorption and dust removal of slag, methanol, acetone, and furfural entrained in gas.

[0035] The small amount of exhaust gas after purification and dust removal is incinerated and discharged, fully meeting the standards.

[0036] 4. This invention can recover furfural, methanol, acetone and other components from the slag vapor, thereby improving the recovery rate of furfural. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the slag and tail gas treatment device of the furfural unit of the present invention;

[0038] In the diagram: 1-Steam-slag separator, 2-Screw conveyor, 3-Belt conveyor, 4-Steam scrubber, 5-Scrubber water pump, 6-Absorber, 7-Fan, 8-Flash tower, 9-Second condenser, 10-First gas-liquid separator, 11-Cooler, 12-Main circulating pump, 13-Second circulating auxiliary pump, 14-Filter press pump, 15-Filter press, 16-First condenser, 17-Second gas-liquid separator, 18-Reboiler, 19-Vacuum regulating valve, 20-Reflux valve, 21-Water regulating valve, 22-Water discharge regulating valve, 23-Sampling port. Detailed Implementation

[0039] The present invention will be further described below with reference to specific embodiments.

[0040] Example 1

[0041] A furfural plant slag and tail gas treatment device, see [link / reference] Figure 1 It includes a steam-slag separator 1, an absorption tower 6, a first gas-liquid separation tank 10, and a filter press 15. The feed end of the steam-slag separator 1 is connected to the slag discharge end of the hydrolysis reactor.

[0042] The bottom of the gas-slag separator 1 is equipped with a screw conveyor 2, and the discharge end of the screw conveyor 2 is equipped with a belt conveyor.

[0043] 3. Sampling ports 23 are provided on the side wall of the absorption tower 6. The internal packing of the absorption tower 6 is grid packing or a combination of grid packing.

[0044] The packing material has the same structure and performance, and the top of the absorption tower 6 has a liquid phase distributor.

[0045] The gas discharge end of the steam-slag separator 1 is connected to the gas inlet end of the absorption tower 6 through a steam scrubber 4. A washing water pump 5 is installed between the steam scrubber 4 and the absorption tower 6, and the input end of the washing water pump 5 is connected to the bottom storage tank of the absorption tower 6.

[0046] The output end of the washing water pump 5 is connected to the inlet end of the steam scrubber 4. The steam scrubber 4 is a venturi structure, containing...

[0047] It includes a converging tube, a throat, a diverging tube, and a dehydrator connected in sequence.

[0048] The exhaust end of the absorption tower 6 is connected to the input end of the first gas-liquid separator 10 via the first condenser 16. The gas output end of the first gas-liquid separator 10 is connected to the tail gas treatment system via the fan 7. The bottom of the absorption tower 6...

[0049] A bottom storage tank is provided, and the liquid output end of the first gas-liquid separator 10 is connected to the bottom storage tank of the absorption tower 6.

[0050] The lower outlet of the absorption tower 6 is connected to the input of the filter press 15 via the filter pump 14; the discharge end of the filter press 15 is connected to both a water regulating valve 21 and a water discharge regulating valve 22, and the other end of the water regulating valve 21 is connected to the bottom storage tank of the absorption tower 6.

[0051] A circulating main pump 12 is installed on one side of the absorption tower 6. The input end of the circulating main pump 12 is connected to the bottom storage tank of the absorption tower 6. A liquid phase distributor is installed at the top of the absorption tower 6. The output end of the circulating main pump 12 is connected to the top of the absorption tower 6.

[0052] The liquid phase distributor is connected.

[0053] A flash evaporator 8 and a second gas-liquid separator 17 are provided on one side of the absorption tower 6. The input end of the flash evaporator 8 is connected to the bottom storage tank of the absorption tower 6 via a pipeline. The gas output end of the flash evaporator 8 is connected to the second gas-liquid separator 17 via a second condenser 9. The gas output end of the second gas-liquid separator 17 is connected to the vacuum system via a vacuum regulating valve 19. The liquid output end of the second gas-liquid separator 17 is connected to a water-aldehyde separator. The internal packing of the flash evaporator 8 is grid packing or packing with the same structure and performance as the grid. A liquid phase distributor is located at the top of the flash evaporator 8. When the sampling port 23 at the bottom of the storage tank of the absorption tower 6 detects that the furfural content in the liquid phase reaches 0.5% to 5%, the vacuum regulating valve 19 is opened for operation, and the flash evaporator 8 will maintain a pressure of -0.05MPa to -0.01MPa. By adding equipment such as the flash evaporator, the complete absorption and dust removal of slag, methanol, acetone, and furfural entrained in the gas can be achieved. The small amount of exhaust gas after purification and dust removal is incinerated and discharged, further reducing environmental pollution.

[0054] The flash distillation tower 8 is also connected to a circulating auxiliary pump 13, a cooler 11, and a reflux valve 20. The input end of the circulating auxiliary pump 13 is connected to the liquid outlet end of the flash distillation tower 8, and the output end of the circulating auxiliary pump 13 is connected to the input end of the cooler 11. The output end of the cooler 11 is simultaneously connected to the input end of the reflux valve 20 and the liquid phase distributor at the top of the absorption tower 6.

[0055] The output end is connected to the upper end of the flash tower 8. The flash tower 8 is also connected to a reboiler 18. The input end of the reboiler 18 is connected to the liquid outlet end of the flash tower 8, and the output end of the reboiler 18 is connected to the side wall of the reboiler 18.

[0056] This invention eliminates the need for traditional steam-slag separation chambers and other facilities, instead employing steam-slag separators and absorption towers. Slag discharge utilizes a screw conveyor, which effectively prevents gas leakage from the steam-slag separator, reducing environmental pollution. Furthermore, it eliminates the need for substantial investment in environmental protection equipment and facilities, saving significant operating and maintenance costs. Simultaneously, this invention allows for the recovery of furfural, methanol, acetone, and other components from the discharged aldehyde vapor, improving the furfural recovery rate.

[0057] Example 2

[0058] A method for treating the exhaust gas from a furfural unit based on the exhaust gas treatment device of Embodiment 1 includes:

[0059] Step S1: After hydrolysis in the hydrolysis vessel is complete, reduce the pressure in the hydrolysis vessel to P1 (in this embodiment, P1 is 0.06).

[0060] With a pressure of ~0.5MPa), the bottom discharge valve of the hydrolysis vessel is opened, and the solid material is discharged to the steam-slag separator 1 under the pressure of gas. The solid material in the steam-slag separator 1 is separated into steam and slag under a pressure of P2 (P2 is -0.001MPa to 0.1MPa in this embodiment). The slag separated by the steam-slag separator 1 is discharged through the bottom screw conveyor 2 of the steam-slag separator 1 and sent to the boiler for use as fuel by the belt conveyor 3. The gas separated by the steam-slag separator 1 is discharged from the top of the steam-slag separator 1. The main components of the gas are: water vapor, furfural vapor, methanol vapor, acetone vapor, etc. The gas is washed by the steam scrubber 4 and then sent to the absorption tower 6.

[0061] Step S2: Gas from the gas scrubber 4 enters the absorption tower 6 from the bottom and reacts with the gas in the absorption tower 6.

[0062] The top spray water contacts in a counter-current manner, where most of the water vapor, methanol vapor, acetone vapor, furfural vapor, and other gases are absorbed; a small amount of non-condensable vapor is discharged from the top of the absorption tower 6, condensed by the first condenser 16, and then separated by the first gas-liquid separator 10. The non-condensable vapor is then sent to the tail gas treatment system by the induced draft fan 7 for tail gas treatment, and the condensate in the first gas-liquid separator 10 flows back to the bottom storage tank of the absorption tower 6; the water in the bottom storage tank of the absorption tower 6 is pressurized by the circulating main pump 12 and then sprayed evenly through the liquid phase distributor at the top of the absorption tower 6.

[0063] Step S3: The slag entrained in the gas from the steam scrubber 4 is removed after being washed by spray water in the absorption tower 6.

[0064] When the slag content in the spray water reaches a certain level (solid content 0.1% to 3%), it is pressurized by the filter press pump 14 and then transported to the filter press 15 to remove the slag from the spray water. The slag is used as biofuel in the boiler, and the purified water is returned to the storage tank of the absorption tower 6 for recycling. When the liquid level in the storage tank of the absorption tower 6 is high, the water regulating valve 21 is closed and the water discharge regulating valve 22 is opened to discharge the excess water to the sewage treatment plant.

[0065] Step S4: Water vapor, methanol vapor, acetone vapor, and furfural entrained in the gas from the steam scrubber 4

[0066] The steam is absorbed after being washed by the spray water in the absorption tower 6. After the concentration of furfural and other components in the spray water reaches M (0.5% to 5% in this embodiment) at the sampling port 23 of the absorption tower 6, the vacuum regulating valve 19 and the reflux valve 20 are opened; the flash tower 8 is started, and a mixture of furfural, water, methanol, acetone and other components is flashed out under the pressure P3 (-0.05 to -0.01 MPa in this embodiment). After being condensed by the second condenser 9 of the flash tower 8, it enters the second gas-liquid separator 17. After separation, the uncondensed steam is sent to the vacuum system through the vacuum regulating valve 19, and the condensate is separated in the water-aldehyde separator. The high-temperature water that absorbs the steam in the absorption tower 6 is pressurized by the circulating auxiliary pump 13 and cooled by the cooler 11 before returning to the absorption tower 6 for recycling.

[0067] The process of this invention can completely absorb and remove slag, methanol, acetone and furfural entrained in the gas. The small amount of exhaust gas after purification and dust removal is incinerated and discharged, further reducing environmental pollution.

[0068] Obviously, the embodiments described above are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

Claims

1. A furfural unit slag and tail gas treatment device, characterized in that, The system includes a steam-slag separator (1), an absorption tower (6), a flash evaporator (8), a first gas-liquid separator (10), and a filter press (15). The feed end of the steam-slag separator (1) is connected to the slag discharge end of the hydrolysis reactor. The gas discharge end of the steam-slag separator (1) is connected to the gas inlet end of the absorption tower (6) through a steam scrubber (4). The exhaust end of the absorption tower (6) is connected to the input end of the first gas-liquid separator (10) through a first condenser (16). The gas output end of the first gas-liquid separator (10) is connected to the tail gas treatment system through a blower (7). The bottom of the absorption tower (6) is provided with a bottom storage tank. The liquid output end of the first gas-liquid separator (10) is connected to the bottom storage tank of the absorption tower (6). The bottom storage tank of the absorption tower (6) is connected to the upper inlet of the absorption tower (6) via a circulating main pump (12). The second outlet of the bottom storage tank of the absorption tower (6) is connected to the lower inlet of the flash tower (8). The third outlet of the bottom storage tank of the absorption tower (6) is connected to the input of the filter press (15) via a filter press pump (14). The fourth outlet of the bottom storage tank of the absorption tower (6) is connected to the inlet of the steam scrubber (4) via a washing water pump (5). The bottom storage tank of the absorption tower (6) is provided with a sampling port (23) on its side wall. The exhaust end of the flash tower (8) is connected to the vacuum system via a second condenser (9) and a second gas-liquid separator. The lower outlet of the flash tower (8) is connected to the vacuum system via a second condenser (9) and a second gas-liquid separator. The liquid end is connected to the upper liquid inlet of the absorption tower (6) and the upper liquid inlet of the flash tower (8) via the circulating auxiliary pump (13) and cooler (11).

2. The furfural unit slag and tail gas treatment device according to claim 1, characterized in that, The bottom of the gas-slag separator (1) is provided with a screw conveyor (2), and the screw conveyor (2) is provided with a cooling device.

3. The furfural unit slag and tail gas treatment device according to claim 2, characterized in that, A washing water pump (5) is provided between the steam scrubber (4) and the absorption tower (6). The input end of the washing water pump (5) is connected to the fourth liquid outlet of the bottom storage tank of the absorption tower (6). The output end of the washing water pump (5) is connected to the liquid inlet of the steam scrubber (4). The outlet end of the steam scrubber (4) is connected to the bottom storage tank of the absorption tower (6). The steam scrubber (4) has a venturi structure and includes a converging tube, a throat tube, a diverging tube, and a dehydrator connected in sequence.

4. The furfural unit slag and tail gas treatment device according to claim 3, characterized in that, The filter press (15) is connected to both a water regulating valve (21) and a water discharge regulating valve (22) at its discharge end. The other end of the water regulating valve (21) is connected to the bottom storage tank of the absorption tower (6).

5. The furfural unit slag and tail gas treatment device according to claim 4, characterized in that, The absorption tower (6) is provided with a circulating main pump (12) on one side. The input end of the circulating main pump (12) is connected to the first liquid outlet end of the bottom storage tank of the absorption tower (6). The top of the absorption tower (6) is provided with a liquid phase distributor. The output end of the circulating main pump (12) is connected to the liquid phase distributor at the top of the absorption tower (6). The internal packing of the absorption tower (6) is grid packing or packing with the same structure and performance as the grid.

6. The furfural unit slag and tail gas treatment device according to claim 5, characterized in that, The absorption tower (6) is provided with a flash tower (8) and a second gas-liquid separator (17) on one side. The first liquid inlet of the flash tower (8) is connected to the second liquid outlet of the bottom storage tank of the absorption tower (6) through a pipeline. The gas outlet of the flash tower (8) is connected to the second gas-liquid separator (17) through a second condenser (9). The gas outlet of the second gas-liquid separator (17) is connected to the vacuum system through a vacuum regulating valve (19). The liquid outlet of the second gas-liquid separator (17) is connected to a water-aldehyde separator.

7. The furfural unit slag and tail gas treatment device according to claim 6, characterized in that, The flash tower (8) is also connected to a circulating auxiliary pump (13), a cooler (11), and a reflux valve (20). The input end of the circulating auxiliary pump (13) is connected to the liquid outlet of the flash tower (8), and the output end of the circulating auxiliary pump (13) is connected to the input end of the cooler (11). The output end of the cooler (11) is simultaneously connected to the input end of the reflux valve (20) and the liquid phase distributor at the top of the absorption tower (6). The output end of the reflux valve (20) is connected to the upper end of the flash tower (8). The flash tower (8) is also connected to a reboiler (18). The input end of the reboiler (18) is connected to the liquid outlet of the flash tower (8), and the output end of the reboiler (18) is connected to the second liquid inlet of the tower bottom of the flash tower (8). The internal packing of the flash tower (8) is grid packing or packing with the same structure and performance as the grid. There is a liquid phase distributor at the top of the flash tower (8).

8. A method for treating the exhaust gas from a furfural unit based on the exhaust gas treatment device of any one of claims 1-7, characterized in that, include: Step S1: After hydrolysis in the hydrolysis vessel is completed, the pressure of the hydrolysis vessel is reduced to 0.06-0.5 MPa. The bottom discharge valve of the hydrolysis vessel is opened, and the solid material is discharged to the steam-slag separator (1) under the pressure of the gas. The solid material in the steam-slag separator (1) is separated into steam and slag under a pressure of -0.001 MPa to 0.1 MPa. The gas separated by the steam-slag separator (1) is discharged from the top of the steam-slag separator (1), washed by the steam scrubber (4), and then transported to the absorption tower (6). Step S2: The gas from the steam scrubber (4) enters the absorption tower (6) from the bottom and comes into countercurrent contact with the spray water at the top of the absorption tower (6). Most of the gas is absorbed by the spray water, and a small amount of non-condensable gas is discharged from the top of the absorption tower (6). After being condensed by the first condenser (16) and separated by the first gas-liquid separator (10), the non-condensable gas is sent to the tail gas treatment system by the induced draft fan (7) for treatment. The condensate in the first gas-liquid separator (10) flows back to the storage tank at the bottom of the absorption tower (6). Step S3: The slag entrained in the gas from the gas scrubber (4) is removed after being washed by the spray water in the absorption tower (6). When the slag content washed down from the spray water reaches a certain level, it is pressurized by the filter press pump (14) and transported to the filter press (15) to remove the slag from the spray water. The slag is used as biofuel in the boiler. The purified water is returned to the bottom storage tank of the absorption tower (6) for recycling. When the liquid level in the bottom storage tank of the absorption tower (6) is high, the water discharge regulating valve (22) is opened to send the water to the sewage treatment plant.

9. The method for treating tail gas from a furfural unit tail gas treatment device according to claim 8, characterized in that: In step S3, the slag content reaches a solid content of 0.1% to 3%.

10. The method for treating tail gas from a furfural unit tail gas treatment device according to claim 8, characterized in that: In step S1: The slag separated by the steam slag separator (1) is discharged through the bottom screw conveyor (2) of the steam slag separator (1). The screw conveyor (2) is equipped with a cooling device and is then sent to the boiler by the belt conveyor (3) for use as fuel. In step S2: the water in the storage tank at the bottom of the absorption tower (6) is pressurized by the circulating main pump (12) and then sprayed out evenly through the liquid phase distributor at the top of the absorption tower (6); In step S3: When the liquid level in the bottom storage tank of the absorption tower (6) is high, close the water regulating valve (21) and open the water discharge regulating valve (22) to discharge the excess water to the sewage treatment plant.

11. The method for treating tail gas from a furfural unit tail gas treatment device according to claim 10, characterized in that, It also includes step S4: Step S4: Water vapor, methanol vapor, acetone vapor, and furfural vapor carried in the gas from the steam scrubber (4) are washed and absorbed by the spray water in the absorption tower (6). The temperature of the spray water will rise. After being pressurized by the circulating auxiliary pump (13) and cooled by the cooler (11), it returns to the absorption tower (6) for recycling. After the furfural component in the spray water reaches a concentration of 0.5% to 5% by the sampling port (23) of the absorption tower (6), the flash tower (8) is put into use. The vacuum regulating valve (19) and the reflux valve (20) are opened. The mixture of furfural, vapor, methanol, and acetone components is flashed out at a pressure of -0.05 to -0.01 MPa. The flash vapor is discharged from the exhaust end of the flash tower (8), condensed by the second condenser (9), and enters the second gas-liquid separator (17). The uncondensed vapor after separation is transported to the vacuum system through the vacuum regulating valve (19). The condensate is separated in the water-aldehyde separator.

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