Process for ammonia dehydration in acrylonitrile production

Abstract

The invention relates to an ammonia dehydrating technology which can be used in the production process of acrylonitrile. The technology comprises the following steps: raw material liquid ammonia is led in an ammonia evaporator for vaporization, ammonia gas which is formed after the vaporization is discharged out via an ammonia gas outlet, and surplus liquid-phase products after the vaporization are partially discharged into a rectifying tower; the liquid-phase products which are discharged into the rectifying tower absorb the heat provided by a reboiler and fractionate the ammonia gas, and the liquid-phase products after fractionating the ammonia gas are partially discharged out of a tower kettle; the heat which the reboiler provides for the rectifying tower is increased or reduced according to the pressure drop or the pressure rise of the ammonia gas at the ammonia gas outlet; the flow of the liquid-phase products discharged from the ammonia evaporator into the rectifying tower is enlarged or decreased according to the decline or the rise of liquid level in the rectifying tower; the flow of the liquid-phase products discharged out of the tower kettle is enlarged or decreased according to the fact whether the temperature of the tower kettle of the rectifying tower is higher or lower than a first set temperature. In the evaporation process of the ammonia, through technology, the liquid discharging opportunity and the liquid discharging amount of the ammonia evaporator are accurately controlled, the evaporation efficiency of the ammonia gas is increased, and the loss of the ammonia is reduced.

Description

technical field [0001] The invention relates to a process for ammonia dehydration in the production process of acrylonitrile. Background technique [0002] Acrylonitrile is a basic organic chemical product and the basic raw material of the three major synthetic materials - synthetic fiber, synthetic rubber, and plastic. Various chemical materials synthesized from it can be seen in all aspects of daily life. The rapid development of the petrochemical industry in recent years has provided a large amount of raw materials for the production of acrylonitrile. On the basis of traditional applications, acrylonitrile has also achieved rapid development in the fields of fine chemicals and deep processing, and has continuously developed new application fields. [0003] At present, more than 95% of acrylonitrile production in the world adopts ammonia and propylene oxidation. At present, there are 12 acrylonitrile production enterprises in my country (including Taiwan), with 16 sets o...

AI Technical Summary

Problems solved by technology

With the progress of production, water continues to accumulate in the evaporator, and the increase of water content greatly hinders the vaporization of liquid ammonia, which greatly affects the performance of the evaporator, and in severe cases, it will cause insufficient ammonia supply and reduce the load of the device

[0005] The current process is to install an ammonia drain tank next to the evaporator, and a heating coil is installed inside the tank, and the valve of the pipeline from the evaporator to the drain tank is opened by manual intermittent operation to discharge liquid ammonia to the drain tank, and then to the heating coil 0.3MPaG steam is introduced into the medium to heat, the ammonia in it is evaporated, and the waste liquid is discharged to the quenching tower for use; during the operation of this process, the timing of liquid discharge, the amount of liquid discharged and the amount of steam introduced are completely subjectively judged by the operator. The amount is large and the state of the evaporator system is unstable

In addition, the discharge liquid discharged into the tank is only discharged after simple evaporation treatment, resulting in a large loss of ammonia

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