In the process of ammonia production, heat exchange is always accompanied. Especially for chemical fertilizer enterprises, the summer temperature rises, and the compressor output is not widespread.

The temperature rises in summer, and the semi-water gas desulfurizes and enters the cleaning tower for cleaning. The cleaning tower is exposed to the sun in the hot sun, the temperature is as high as 40-43 cc, so that the half-water gas at 40 cc water saturated vapor pressure is 880 mmH0 (8.63 kPa), and the semi-water gas is at 2600 mmH0 ( 25.50kPa) (G) The cleaning tower enters the compressor section. Generally, the half-water gas main pipe from the cleaning tower to the compressor section is 100m long, the flow rate is 810m/s, and the temperature can reach 44cc before reaching the compressor, so the compressor is In summer, there is a phenomenon of “no gas”.

In the summer, the water temperature is high, the compressor “has no gas”, poor heat transfer effect, and high energy consumption are the main problems that restrict the production of synthetic ammonia. For fertilizer enterprises, summer is the peak season for sales, and the production equipment needs to be operated at full capacity. In response to the above problems, we have conducted repeated research and decided to adopt a new type of tubular graphite heat exchanger, which has achieved good economic benefits before being used in the compressor section.

1 New graphite heat exchanger equipment (1) Impervious graphite material Impervious graphite is a new type of structural material made by artificial graphite and synthetic resin by impregnation, pressing, casting, etc. It is resistant to all other non-metals. Corrosive materials differ in that they have a high degree of chemical stability, high thermal conductivity, no contamination of the medium, and are less prone to fouling, thus greatly expanding their application range.

In terms of chemical stability, impervious graphite is resistant to most chemical media except for strong oxidizing acids and bases, especially those containing chloride ions. In terms of thermal conductivity, the thermal conductivity of impregnated graphite is 100~10W/m·K, and its thermal conductivity is similar to that of copper and aluminum. It is 2.5 times higher than ordinary carbon steel. It is usually based on this feature. .

In terms of thermal stability, phenolic impregnated graphite can generally withstand temperatures of around 70%, and its coefficient of thermal expansion is small, about 0.4 to 0.45 x 10/K.

(2) New heat exchange equipment The new tube-type graphite heat exchanger has fixed tube sheets at both ends. The tube sheets and heat exchange tubes are connected with high-elastic and corrosion-resistant rubber materials. Three elastic seals are implemented. The equipment structure is simple and the earthquake resistance is good. , good heat transfer performance, and low operating resistance, easy to maintain and clean. The stress damage caused by the obvious difference of the linear expansion coefficient between the binder and the impregnated graphite block material in the structure of the traditional graphite heat exchanger is completely eliminated, and the "difference elongation" and temperature unevenness of the graphite heat exchange tube under the action of temperature are eliminated. Destructive effects caused by factors. Even under large temperature differences, the operation is stable and reliable. All the equipments are connected by active connection, the pipe change is convenient, the heat exchange area is not reduced, and the whole machine scrapping caused by the pipe blocking is avoided. The new graphite heat exchanger has a allowable pressure of 1.0 MPa and a service temperature of 150 cc.

2 Application in Synthetic Ammonia In order to solve the problem of “gaslessness” of the compressor, some manufacturers used the mixed heat exchangers mainly of spray type and spray type, and some directly used chilled water for cooling. The former has a series of problems such as high power consumption, loss of effective gas components, gas-water separation, etc., while the latter has large investment and higher energy consumption. Adding a graphite tube gas cooler in front of the compressor, taking into account the average summer gas temperature of 46cC, the lower temperature of the disposable groundwater (temperature of l6) is used to cool the gas, so that the temperature of the compressor population can be reduced by 10~ in summer. Above C, the compressor can be kept at full capacity at all times.

(1) Analysis of application According to the Crabone equation: PV=MRT, it can be known that reducing the intake air temperature of the compressor can increase the compressor air volume. Calculated with 8×104t/a synthetic ammonia (investment about 500,000 yuan), the heat transfer area of ​​the new graphite heat exchanger is 712mz, which can increase the gas transmission by 2_3% according to the reduction of l0cc.

(2) Economic benefits Under normal circumstances, the original system produces 280 tons of ammonia per day, which is converted according to ammonia production. After the new graphite cooler is put into production, the output can be increased by 280×2.3%=6.44(), and the high temperature season is 150 days per year. Calculated, the annual increase in production is therefore 6.44 × l50 = 966 (fa). According to the price of synthetic ammonia l800 yuan / t, tons of ammonia consumption of coal 700 × 1.3 = 900 yuan, the other cost of tons of ammonia 50 yuan, water consumption costs about 500 yuan / day, the annual increase in benefits: (1800-900-50) × 966-l50×500=74,60 million yuan According to the above calculations, it can be seen that the synthetic ammonia production unit adopts a new type of graphite heat exchanger in the population of the compressor to effectively increase the equipment operating load, increase the energy consumption, and recover the equipment in less than one year. investment.

In short, from the use of several manufacturers such as Ningyang Feida. The use of new graphite heat exchangers has achieved satisfactory results. We believe that its use prospects will be better.


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