Reaction kettle for purifying urea

Abstract

The utility model discloses a reaction kettle for purifying urea, and belongs to the field of vehicle urea purification. Comprising a feeding system, an extraction stirring system and a separation system, the feeding system comprises a feeding port, a water inlet and a water circulation system, the extraction stirring system comprises an extraction stirring kettle and a stirring paddle, and a filter plate is arranged at the bottom of the extraction stirring kettle; the separation system comprises a storage tank, a centrifugal machine, a first recovery tank used for recovering a urea solution and a second recovery tank used for recovering urea particles. The feeding port comprises a stacking platform and a funnel-shaped feeding port. And the filter plate is a reversible plastic baffle with holes. The reaction kettle for purifying urea provided by the utility model can achieve the effects of reducing the energy consumption of equipment, improving the urea purification efficiency and being simple in structure.

Description

TECHNICAL FIELD

[0001] The utility model relates to the urea purification for vehicle, especially a reaction kettle for urea purification. BACKGROUND

[0002] Urea water can purify NO x , and is widely used in the gas purification system of large diesel vehicles. The automobile urea is a liquid used in the SCR technology to reduce the nitrogen oxide pollution in the exhaust gas of diesel vehicles. The automobile urea is used for reducing nitrogen oxide compounds, and can be used as a reducing agent of the SCR (Selective Catalytic Reduction) system. The automobile urea solution reacts with the nitrogen oxide in the exhaust gas of heavy trucks, passenger cars and other diesel vehicles to generate N2 and H2O to purify the exhaust gas.

[0003] The main impurity in the automobile urea solution is biuret, which can significantly increase the generation and accumulation of fouling. The content of the impurity is clearly required in the relevant standards of automobile urea. The urea is in a high temperature and high pressure environment during the production process. The urea will undergo condensation reaction during the granulation process to generate biuret. The urea water is easy to contain biuret during the preparation process. The purity of the automobile urea is very high, and the ordinary urea or urine cannot meet the high purity requirement of the automobile urea.

[0004] At present, the purification equipment of urea particles mainly uses recrystallization equipment. The solubility difference of urea at different temperatures is used to realize the purification. However, the recrystallization process involves the processes of heating and cooling, the energy consumption of the equipment is high, the crystallization process is not easy to control, the loss of raw materials is large, and it is difficult to be applied in industrialization. SUMMARY

[0005] The utility model aims at providing a urea purification reaction kettle which can reduce the energy consumption of the equipment, improve the urea purification efficiency and has a simple structure.

[0006] Technical scheme: the urea purification reaction kettle, including feeding system, extraction stirring system and separation system which are sequentially arranged from top to bottom, the feeding system includes feeding port, water inlet and water circulation system, the extraction stirring system includes extraction stirring kettle, the extraction stirring kettle is internally provided with stirring paddle, the extraction stirring kettle bottom is equipped with filter plate, the separation system includes storage tank, centrifuge, first recovery tank for recovering urea solution and second recovery tank for recovering urea particles.

[0007] Preferably, the feeding port includes stacking platform and funnel-shaped pouring port.

[0008] Preferably, the pipeline diameter of the water inlet is 140-160mm, preferably 150mm.

[0009] Preferably, the water circulation system is provided with a normal temperature water supply device.

[0010] Preferably, the volume of the extraction stirred tank is 10-30m 3 , preferably 20m 3 , and the extraction stirred tank is provided with a circulating water jacket.

[0011] Preferably, the rotating speed of the stirring paddle is constant at 90-100r / min, preferably 100r / min.

[0012] Preferably, the filter plate is a plastic baffle plate with holes, and the diameter of the holes is not greater than 1mm, preferably 1mm.

[0013] Preferably, the filter plate is a reversible structure.

[0014] Advantages: compared with the prior art, the reaction kettle has the following obvious advantages: (1) the reaction kettle utilizes the different solubility of impurity biuret and raw material urea in water to purify urea, which can reduce equipment energy consumption, avoid high temperature and low temperature in the recrystallization process, and overcome the defects of high equipment energy consumption; (2) the reaction kettle utilizes the different solubility of biuret and urea in water to effectively remove impurities in urea, which can effectively reduce the purification cost and well control the purification effect, reduce the urea raw material loss rate, and the urea raw material comprehensive recovery rate reaches 93%, which is much higher than that of the recrystallization purification scheme; (3) the structure of the reaction kettle is simple and convenient to operate, and continuous production can be realized through circulation purification; (4) the reaction kettle can realize effective separation of solution and urea particles, and ensure that the application of particles is not affected by the solution; (5) the reaction kettle can effectively remove impurities in urea, and the purified urea can be used in vehicle urea, which can improve the anti-fouling performance of vehicle urea. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a whole appearance schematic view of the utility model. DETAILED DESCRIPTION

[0016] The technical scheme of the utility model will be further described below in combination with examples.

[0017] As shown in the figure, the urea purification reaction kettle of the utility model comprises a feeding system, an extraction stirring system and a separation system arranged in sequence from top to bottom, wherein the feeding system comprises a feeding port 1, a water inlet 2 and a water circulation system 3, the extraction stirring system comprises an extraction stirred tank 4, the extraction stirred tank 4 is provided with a stirring paddle 5, the bottom of the extraction stirred tank 4 is provided with a filter plate 6, and the separation system comprises a storage tank 7, a centrifugal machine 8, a first recovery tank 9 for recovering urea solution and a second recovery tank 10 for recovering urea particles.

[0018] The feeding inlet 1 comprises a stacking platform and a funnel-shaped feeding inlet, facilitating unpacking and feeding of 50kg small-package agricultural urea.

[0019] The water inlet 2 is connected to a three-stage pure water production system, and the pipeline has a diameter of 150mm, and the pure water is pumped from a pure water tank to the purification tank.

[0020] Since the urea particles absorb a large amount of heat during the dissolution process, the temperature of the reaction system decreases, affecting the purification effect; the water circulation system 3 comprises a water circulation pipeline, a normal-temperature water supply device and a water storage tank, and municipal tap water is circulated, mainly used for heating and circulating the low-temperature water in the agricultural urea particle dissolution process to normal temperature, and the pipeline has a diameter of 150mm and the water storage tank has a capacity of 1t.

[0021] The extraction stirred tank 4 has a volume of 20m 3 , and a circulating water jacket is arranged on the outer side to circulate the low temperature generated during the purification process to room temperature.

[0022] The stirring paddle 5 has a constant rotating speed of 100r / min, ensuring that the urea particles at the bottom can be circulated and rotated.

[0023] The filter plate 6 is a plastic baffle with holes, and the holes in the middle have a diameter of 1mm, ensuring that the saturated urea particles do not deposit at the bottom of the reaction tank during the purification process, so as to improve the purification efficiency. The filter plate 6 can be flipped, and after the purification is completed, the liquid is first emptied, then the filter plate is flipped, and then the urea particles are discharged.

[0024] The centrifuge 8 can separate the water contained in the urea particles, so as to reduce the water content in the urea particles and ensure the stability in the subsequent production process.

[0025] The first recovery tank 9 has two functions, the first is to collect the solution flowing from the bottom of the filter plate, and the second is to collect the solution after the centrifuge treatment; at the same time, the first recovery tank 9 is provided with a pump, which can pump the urea solution back to the extraction stirred tank 4 for reuse.

[0026] The second recovery tank 10 is a collection container for collecting urea particles from which impurities have been removed, and the bottom is provided with a valve to discharge the particles for production in the vehicle urea blending workshop.

[0027] The working principle of the reaction kettle is as follows: agricultural urea particles are added to the reaction kettle through the feed inlet 1, a certain amount of pure water is added through the water inlet 2, and the urea particles are first dissolved by the stirring paddle 5. At the same time, the water circulation system is opened and the circulation heating is started, and when the temperature rises to room temperature, a certain amount of urea particles are added to the feed inlet 1 again, and the stirring is continued for 2h. At this time, the urea solution reaches the saturation state, and the excess urea particles cannot be dissolved in water, but exist in the water in a suspended state. However, since the solubility of biuret in water is greater than that of urea particles in water, the biuret in the secondly added urea particles can continue to dissolve in water. After the stirring is completed, the urea solution mixed with biuret is discharged into the first recovery tank 9 for standby. Turn over the filter plate 6, discharge the remaining urea particles without biuret and a small amount of water into the centrifuge 8, discharge the particles into the second recovery tank 10, and discharge the remaining aqueous solution into the first recovery tank 9. After all is completed, the solution is pumped back into the extraction stirring kettle 4, and the next round of purification is continued, and the process is repeated until the tenth round is completed. The experimental data is shown in Table 1.

[0028] Table 1 Experimental data of ten rounds of purification

[0029]

[0030]

[0031] According to Table 1, it can be seen that using the reaction kettle provided by the utility model, the recovery rate of urea purification is as high as 93.66%, which is much higher than that of the recrystallization purification scheme (the recovery rate of one-time recrystallization is about 80%, the recovery rate of two-time recrystallization is about 65%, and the recovery rate of three-time recrystallization is only about 52%) (Meng Jiaoran, Duan Manlei, Xia Wa, et al. Purification of urea by recrystallization method [J]. Chemical reagents, 2020, 42(2): 4).

Claims

1. A reaction vessel for urea purification, characterized in that, The system includes a feeding system, an extraction stirring system, and a separation system arranged from top to bottom. The feeding system includes a feed inlet (1), a water inlet (2), and a water circulation system (3). The extraction stirring system includes an extraction stirring vessel (4), which is equipped with a stirring paddle (5) and a filter plate (6) at the bottom. The separation system includes a storage tank (7), a centrifuge (8), a first recovery tank (9) for recovering urea solution, and a second recovery tank (10) for recovering urea particles.

2. The reaction vessel for urea purification according to claim 1, characterized in that, The feed inlet (1) includes a stacking platform and a funnel-shaped inlet.

3. The reaction vessel for urea purification according to claim 1, characterized in that, The diameter of the inlet (2) is 140-160mm.

4. The reaction vessel for urea purification according to claim 1, characterized in that, The water circulation system (3) is equipped with a normal temperature water supply device.

5. The reaction vessel for urea purification according to claim 1, characterized in that, The extraction stirring vessel (4) has a volume of 10-30 m³. 3 The extraction stirring vessel (4) is equipped with a circulating water jacket on the outside.

6. The reaction vessel for urea purification according to claim 1, characterized in that, The rotational speed of the stirring paddle (5) is constant at 90-100 r / min.

7. The reaction vessel for urea purification according to claim 1, characterized in that, The filter plate (6) is a plastic baffle with holes, and the diameter of the holes is no greater than 1 mm.

8. The reaction vessel for urea purification according to claim 1, characterized in that, The filter plate (6) is a flip-up structure.

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