Application of the hottest ultrafiltration technol

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Application of ultrafiltration technology in ammonia separator

I. brief introduction

our company is a medium-sized chemical enterprise with an annual output of 200000 tons of synthetic ammonia, 250000 tons of urea, 100000 tons of compound fertilizer, 40000 tons of soda ash and many other chemical products. A new set φ The 1600 synthetic ammonia system was completed and put into operation in October 1999. There are three TC450 turbine circulators in the system, two for operation and one for standby φ 1000 cold cross φ There is one set of 1000 ammonia separators respectively, and its internals are traditional cyclone plate and baffle plate structures. The turbine circulator is located behind the ammonia separators. Due to the poor separation effect of the original ammonia separators, the liquid is brought to the turbine, resulting in the abnormal operation of the turbine circulator and frequent maintenance of the turbine. Since the two turbines cannot operate at the same time, the system can only maintain low load production. The gas flow into the tower is 100000~140000 m3 (standard)/h, which directly affects the economic benefits of our company. Therefore, it is decided to reform the ammonia separation. After theoretical calculation and expert argumentation, it is believed that φ 1600 in synthetic ammonia system φ The diameter of 1000 cold cross and ammonia is smaller, and the diameter of cold cross and ammonia must be within φ Above 1200, if replaced by φ 1200 ammonia, only the high-pressure outer cylinder needs to increase the cost of more than 500000 yuan, and also needs a certain production cycle. After investigation, it is decided to adopt the ultrafiltration technology of Xi'an ultrafiltration purification Engineering Co., Ltd. The technology used in ammonia separator is the first in China. Using ammonia φ The inner part of 1000 high-pressure outer cylinder is redesigned. The inner part is designed and manufactured by our company, and the cost is less than 100000 yuan. It was put into systematic production in August 2000. After more than 3 months of use, the effect is very good. See Figure 1 for the process flow

Figure 1 process flow diagram of synthetic ammonia system

1-ammonia converter; 2-heat exchanger outside the tower; 3-water cooler; 4-ammonia separator; 5-turbine

6-circulating gas oil-water separator, such as TPE automobile sealing strip, TPE automobile foot pad and other products; 7-fresh gas oil-water separator; 8-cold exchanger

9- ammonia evaporator; 10 - demister; 11 soft water preheater; 12 waste heat boiler

II. Use and effect of ammonia before technical transformation

it saves time again

our company φ Since the 1600 synthesis system was put into operation in 1999, it has been unable to switch to high load production for many reasons, one of which is the poor effect of raw ammonia. Due to the poor effect of ammonia separation, it is difficult to establish the ammonia level, which brings great difficulty to the operation. At the same time, samples were taken from the ammonia gas outlet pipe for analysis. The ammonia content in the gas was as high as more than 10%, and the gas discharged from the sampling port at the lower part of the pipe could be seen as foggy ammonia. Because a large amount of atomized liquid ammonia is brought to the turbine, so that a large amount of liquid ammonia is discharged from the turbine oil drain tank, causing the turbine to fail to operate normally. At the same time, if the microcomputer function is strong, it can directly print the synthesis system and have the following adverse effects:

(1) the ammonia generated by the synthesis reaction has not been effectively separated, which directly affects the output and economic benefits

(2) bring liquid to the turbine circulator, causing the turbine to produce liquid hammer, affecting the normal operation of the turbine, and even damaging the turbine

(3) increased the load of cold crossover, resulting in high ammonia content in the tower, reduced synthetic reaction rate, increased system pressure and resistance, which not only increased energy consumption, but also affected normal production

III. application effect of ammonia after technical transformation

according to the actual situation of our plant, the design flow is 180000 m3 (standard)/h, and the system pressure is 26mpa. It was put into production in early August 2000, and the effect is obvious. When the operating temperature is about 30 ℃ and the system pressure is 26mpa, the ammonia content in the ammonia outlet gas is generally about 8.4%, which is the saturated ammonia content in the nitrogen hydrogen mixed gas under this state, and the turbine circulator operates normally. On October 9, two turbines were opened at the same time, and the gas flow into the tower reached 215000 m3 (standard)/h, and the ammonia content in the ammonia outlet gas was 8.6%. Due to the poor cold cross effect, the ammonia content in the gas entering the tower is high, resulting in the increase of system pressure and forced to reduce the gas volume. However, two turbines have been opened to maintain the gas entering the tower at about 180000 m3 (standard)/h. At present, we are working on the transformation of the cold exchange internals, and we still decide to adopt ultrafiltration technology. The specific application effects are as follows:

(1) ultrafiltration technology is adopted to avoid the liquid hammer phenomenon caused by the entrainment of a large number of droplet liquid ammonia into the turbine, which is conducive to the normal operation of the turbine; It avoids production reduction and rush repair, and reduces the power consumption of turbines and ice machines at the same time

(2) with ultrafiltration technology, there will be no liquid ammonia mist droplets at the ammonia outlet, and the ammonia content at the ammonia outlet will be reduced from 19% to about 8.4%

(3) with ultrafiltration technology, the ammonia content in the tower can be reduced (0.2~0.5)% under normal circumstances. If the annual output of synthetic ammonia is 140000 tons, the gas flow into the tower is 230000 m3 (standard)/h, and the ammonia content into the tower decreases by 0.2%, the ammonia recovered per hour is: 17 × 0.2% × 230000/22.4=349.11kg/h, the annual recovery of ammonia is 349.11 × 7200 = more than 2514 tons

at present, our company has applied ultrafiltration technology to methanol production system φ 800 oil separation and synthetic ammonia system φ 70 due to the structure of the packaging bag, it can be customized according to requirements

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