Pretreatment device for nitrobenzene waste acid

Abstract

The utility model relates to a pretreatment device for nitrobenzene waste acid, which comprises an organic matter separation tower and heating equipment, steam condensation and settling separation equipment and vacuum generation and tail gas absorption equipment, the organic matter separation tower and heating equipment comprises an organic matter separation tower and a heater which are communicated, and the upper part of the organic matter separation tower is provided with a nitrobenzene waste acid inlet; a live steam inlet is formed in the lower part of the organic matter separation tower; a gas phase outlet is formed in the top of the organic matter separation tower; the steam condensation and settling separation equipment comprises a benzene raw material inlet pipe, a condenser, a settling tank and storage tanks which are communicated in sequence; the storage tanks comprise a benzene storage tank and a dilute nitric acid storage tank; the vacuum generation and tail gas absorption equipment comprises a vacuum unit and a tail gas oxidation tower, the condenser is communicated with the tail gas oxidation tower through the vacuum unit, and the tail gas oxidation tower is communicated with the dilute nitric acid storage tank. According to the utility model, various substances of the nitrification waste acid can be respectively recovered, so that the emission of pollutants is reduced; the risk of blocking the condenser is avoided, and the operation stability of the device is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of pretreatment devices, specifically to a kind of pretreatment device of nitration benzene class waste acid. BACKGROUND

[0002] Existing domestic aromatic nitration device is widely used, such as in dye industry chlorobenzene, benzene nitration, in TDI, MDI toluene nitration, general benzene nitration process uses nitric acid and sulfuric acid mixed acid as nitration agent, while producing product will produce mixture containing small amount of nitric acid, nitrobenzene, nitroso sulfuric acid, sulfuric acid and water.

[0003] Existing nitration benzene device is matched with sulfuric acid concentration recycling device, but nitration waste acid recovery treatment directly uses vacuum distillation concentration to recycle, but the pretreatment step is not clear enough, resulting in part of device in the process of driving nitro compound is blocked in distillation process, nitroso sulfuric acid is not completely decomposed, resulting in tail gas with yellow smoke phenomenon in vacuum evaporation equipment, influence device operation. UTILITY MODEL CONTENT

[0004] In order to overcome the deficiencies in the prior art, the utility model provides a kind of pretreatment device of nitration benzene class waste acid, nitration benzene class waste acid is decomposed in pretreatment device in nitration benzene class waste acid before entering concentration device, and the problem of nitro compound blockage is solved, ensure stable operation of device, reduce pollutant emission.

[0005] The technical scheme adopted by the utility model is as follows:

[0006] A kind of pretreatment device of nitration benzene class waste acid, the device includes organic matter separation tower and heating equipment, steam condensation and sedimentation separation equipment and vacuum generation and tail gas absorption equipment arranged in sequence, the organic matter separation tower and heating equipment include organic matter separation tower and heater, the upper portion of the organic matter separation tower is equipped with nitration waste acid import, the lower portion of the organic matter separation tower is equipped with live steam import, the top of the organic matter separation tower is equipped with gas phase outlet, and the bottom of the organic matter separation tower is communicated with the heater;The steam condensation and sedimentation separation equipment includes benzene class raw material inlet pipe, condenser, settling tank and storage tank communicated in sequence, the storage tank includes benzene storage tank and dilute nitric acid storage tank;The gas phase outlet is communicated with the condenser by gas phase inlet pipe, and the benzene class raw material inlet pipe is communicated with the gas phase inlet pipe;The vacuum generation and tail gas absorption equipment includes vacuum unit and tail gas oxidation tower, and the condenser is communicated with the tail gas oxidation tower by vacuum unit, and the tail gas oxidation tower is communicated with the dilute nitric acid storage tank.

[0007] As preferred, the heater is sulfuric acid heater, one end of the sulfuric acid heater is communicated with heating source inlet pipe, the other end of the sulfuric acid heater is communicated with the output pipe of impurity-removed dilute sulfuric acid, and the heating heat source is heat-conducting oil or steam.

[0008] As preferred, the upper part of the settling tank is provided with a first outlet, and the lower part of the settling tank is provided with a second outlet.

[0009] As preferred, the first outlet is communicated with the top of the benzene storage tank, and the second outlet is communicated with the top of the dilute nitric acid storage tank.

[0010] As preferred, the benzene storage tank is communicated with the nitration device through a first conveying pump.

[0011] As preferred, the dilute nitric acid storage tank is communicated with the nitric acid recovery device through a second conveying pump.

[0012] As preferred, the upper part of the tail gas oxidation tower is communicated with a hydrogen peroxide inlet pipe.

[0013] As preferred, the condenser is communicated with the lower part of the tail gas oxidation tower through a vacuum unit.

[0014] As preferred, the lower part of the tail gas oxidation tower is communicated with the top of the dilute nitric acid storage tank.

[0015] The beneficial effects of the present application are as follows:

[0016] 1. The present application sequentially sets the organic matter separation tower, the heating equipment, the steam condensation and settling separation equipment, and the vacuum generation and tail gas absorption equipment.

[0017] 2. The present application sets a benzene raw material inlet pipe in front of the condenser and communicates it with the gas phase inlet pipe. ATTACHMENT DESCRIPTION

[0018] Figure 1 is a structural schematic diagram of the present application. DETAILED DESCRIPTION

[0019] The present application will be further described in combination with the drawings and specific embodiments, but the protection scope of the present application is not limited thereto.

[0020] REFERENCE Figure 1A pretreatment device for nitration phenyl series waste acid, the device comprises organic matter separation tower and heating equipment, steam condensation and sedimentation separation equipment and vacuum generation and tail gas absorption equipment in sequence, the organic matter separation tower and heating equipment comprises organic matter separation tower 1 and sulfuric acid heater 2, the upper portion of the organic matter separation tower 1 is provided with nitration waste acid inlet 3, the lower portion of the organic matter separation tower 1 is provided with live steam inlet 4, the top of the organic matter separation tower 1 is provided with gas phase outlet 5, and the bottom of the organic matter separation tower 1 is communicated with the sulfuric acid heater 2.

[0021] The steam condensation and sedimentation separation equipment comprises phenyl series raw material inlet pipe 8, condenser 9, sedimentation tank 10 and storage tank in sequence, the storage tank comprises phenyl series storage tank 11 and dilute nitric acid storage tank 12; the gas phase outlet 5 is communicated with the condenser 9 through gas phase inlet pipe 6, the phenyl series raw material inlet pipe 8 is communicated with the gas phase inlet pipe 6; before the gas phase enters the condenser, the production raw material of nitrobenzene, i.e. phenyl series substance, is sprayed into the condenser inlet, the dissolved and evaporated nitrobenzene series substance is prevented from blocking the condenser. The upper portion of the sedimentation tank 10 is provided with first outlet 14, and the lower portion of the sedimentation tank 10 is provided with second outlet 15, the first outlet 14 is communicated with the top of the phenyl series storage tank 11, and the second outlet 15 is communicated with the top of the dilute nitric acid storage tank 12; the phenyl series storage tank 11 is communicated with the nitration device 7 through first conveying pump 16, and the dilute nitric acid storage tank 12 is communicated with the nitric acid recovery device 13 through second conveying pump 17.

[0022] The vacuum generation and tail gas absorption equipment comprises vacuum unit 18 and tail gas oxidation tower 19, the upper portion of the tail gas oxidation tower 19 is communicated with hydrogen peroxide inlet pipe 20, the condenser 9 is communicated with the lower portion of the tail gas oxidation tower 19 through the vacuum unit 18, and the lower portion of the tail gas oxidation tower 19 is communicated with the top of the dilute nitric acid storage tank 12. The condensed liquid is subjected to sedimentation separation, the phenyl series substance is separated and returned to the nitration device, and the dilute nitric acid is mixed with the dilute nitric acid absorbed by the tail gas absorption tower and then sent to the nitric acid recovery device.

[0023] The working principle of the organic matter separation tower and heating equipment, the steam condensation and sedimentation separation equipment and the vacuum generation and tail gas absorption equipment is as follows:

[0024] The organic matter separation tower and heating equipment:

[0025] The nitration waste acid enters the organic matter separation tower, under the condition of 10-50 kpa absolute pressure, a certain amount of live steam is added at the bottom of the organic matter separation tower, the steam addition amount is 5-20% of the mass ratio of the nitration waste acid, the tower kettle is heated through the heater, the tower kettle temperature is controlled at 140-175 DEG C, the nitration waste acid is decomposed into nitrogen dioxide and sulfuric acid in the filler layer and the steam generated by the tower kettle heating and the added primary live steam, and the nitrobenzene series substance is evaporated, and the tower top outlet temperature is controlled to be not lower than 110 DEG C.

[0026] Steam condensation and sedimentation separation device:

[0027] The production raw material benzene is injected into the condenser inlet after the gas phase enters the condenser and nitrobenzene is added, the benzene addition amount is 3-10% of the nitration waste acid addition amount by mass ratio, the temperature control condenser outlet temperature is about 40 DEG C, the nitrobenzene in the gas phase is dissolved by the raw material benzene, and the condenser is not blocked, and the nitrogen dioxide reacts with water in the condenser to produce part of the nitric acid into the condensate, part of the production of nitrogen monoxide non-condensable gas, into the vacuum system, and a plurality of materials are mixed into the sedimentation tank (dilute nitric acid sedimentation tank), the benzene is separated from the water, the benzene is returned to the nitration device, and the dilute nitric acid is removed to the nitric acid recovery device.

[0028] Vacuum generation and tail gas absorption device:

[0029] The gas phase enters the vacuum unit (vacuum generation device), the non-condensable gas in the gas phase enters the tail gas oxidation tower (atmospheric oxidation absorption tower), hydrogen peroxide is added to the upper part of the tower to oxidize nitrogen monoxide, and the dilute nitric acid is mixed with the condensed dilute nitric acid to remove the nitric acid recovery device.

[0030] When the utility model is used, the nitration waste acid is added with live steam to promote the hydrolysis of nitrosyl sulfuric acid in the separation process, the production raw material benzene of nitrobenzene is added before entering the condenser, the nitrobenzene is dissolved, the condenser is prevented from being blocked, the waste water after condensation is separated, the benzene is recovered and returned to the nitration device, the non-condensable gas is oxidized by hydrogen peroxide to generate dilute nitric acid after the vacuum system, and the dilute nitric acid is mixed with the condensed nitric acid to remove the nitric acid recovery device.The utility model can recover various substances of nitration waste acid, reduce the emission of pollutants, solve the problem of high freezing point of nitrobenzene, prevent the condenser from being blocked, and improve the operation stability of the device.

[0031] The above specific embodiment is used to explain and illustrate the utility model, rather than limit the utility model, and any modification and change of the utility model within the spirit and protection scope of the claims falls within the protection scope of the utility model.

Claims

1. A pretreatment device for nitrobenzene series waste acid, characterized by: The device comprises an organic matter separation tower and heating device, steam condensation and sedimentation separation device and vacuum generation and tail gas absorption device arranged in sequence, the organic matter separation tower and heating device comprises an organic matter separation tower and a heater, the upper part of the organic matter separation tower is provided with a nitrated waste acid inlet, the lower part of the organic matter separation tower is provided with a live steam inlet, the top of the organic matter separation tower is provided with a gas phase outlet, and the bottom of the organic matter separation tower is communicated with the heater; the steam condensation and sedimentation separation device comprises a benzene raw material inlet pipe, a condenser, a sedimentation tank and a storage tank communicated in sequence, the storage tank comprises a benzene storage tank and a dilute nitric acid storage tank; the gas phase outlet is communicated with the condenser through a gas phase inlet pipe, and the benzene raw material inlet pipe is communicated with the gas phase inlet pipe; the vacuum generation and tail gas absorption device comprises a vacuum unit and a tail gas oxidation tower, the condenser is communicated with the tail gas oxidation tower through the vacuum unit, and the tail gas oxidation tower is communicated with the dilute nitric acid storage tank.

2. The pretreatment device for nitrobenzene waste acid according to claim 1, characterized in that: The heater is a sulfuric acid heater.

3. The pre-treatment device for nitration phenyl series waste acid according to claim 1, characterized in that: The upper part of the sedimentation tank is provided with a first outlet, and the lower part of the sedimentation tank is provided with a second outlet.

4. The pretreatment device for nitrobenzene waste acid according to claim 3, characterized in that: The first outlet is communicated with the top of the benzene storage tank, and the second outlet is communicated with the top of the dilute nitric acid storage tank.

5. The pre-treatment device for nitration phenyl series waste acid according to claim 1, characterized in that: The benzene storage tank is communicated with the nitration device through a first conveying pump.

6. The pre-treatment device for nitration phenyl series waste acid according to claim 1, characterized in that: The dilute nitric acid storage tank is communicated with the nitric acid recovery device through a second conveying pump.

7. The pre-treatment device for nitration phenyl series waste acid according to claim 1, characterized in that: The upper part of the tail gas oxidation tower is communicated with a hydrogen peroxide inlet pipe.

8. The pre-treatment device for nitration phenyl series waste acid according to claim 1, characterized in that: The condenser is communicated with the lower part of the tail gas oxidation tower through the vacuum unit.

9. The pre-treatment device for nitration phenyl series waste acid according to claim 1, characterized in that: The lower part of the tail gas oxidation tower is communicated with the top of the dilute nitric acid storage tank.

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