Method and device for improving ammoxidation rate of nitric acid manufacture

Abstract

The invention discloses a method for improving ammoxidation rate of nitric acid manufacture. The method is characterized by comprising the steps: air filtration of four-level dry-type filtration, liquid ammonia filtration using first-level filtration to remove impurity, cool gas ammonia filtration of integrated membrane separation, and hot gas ammonia filtration of integrated membrane separation, so that the impurity in the process gas is separated in high efficiency under the conditions of low temperature, low speed, multi-level, and high precision. The invention further discloses a device for using the method. The device is characterized by comprising an air filter with four-level dry-type filter, a liquid ammonia filter with magnetic SF membrane filter element, and a cool gas ammonia filter and hot gas ammonia filter with integrated membrane separation device. The method is capable of, after improving the purifying degree of the nitric acid manufacture raw material, effectively protecting the catalyst, and improving the ammoxidation rate. Few devices are increased, the purifying is good, and the energy consumption is not increased.

Description

technical field [0001] The invention relates to the field of nitric acid production, in particular to a method and device for improving the ammonia oxidation rate of nitric acid production. Background technique [0002] In the production process of nitric acid, ammonia is consumed as a raw material. In actual production, the ammonia consumption mainly depends on the ammonia oxidation rate. [0003] Reasons for high ammonia consumption are: 1. Poor air quality. In the double pressurized nitric acid process, since the catalytic oxidation reaction of ammonia is carried out under the action of the catalyst, if the air contains impurities such as toxic gas, rust, dust, etc., it is easy to cause catalyst poisoning or the active surface of the catalyst is covered, making the catalyst The activity of ammonia is reduced, resulting in low ammonia oxidation rate and high ammonia consumption. After the catalyst is covered and poisoned by dust, in less serious cases, it is not easy to ...

AI Technical Summary

Problems solved by technology

[0003] Reasons for high ammonia consumption are: 1. Poor air quality

In the double pressurized nitric acid process, since the catalytic oxidation reaction of ammonia is carried out under the action of the catalyst, if the air contains impurities such as toxic gas, rust, dust, etc., it is easy to cause catalyst poisoning or the active surface of the catalyst is covered, making the catalyst reduced activity, resulting in low ammonia oxidation rate and high ammonia consumption

After the catalyst is covered and poisoned by dust, in less serious cases, it is not easy to find the problem from the surface of the platinum mesh, and it is often ignored in production. In severe cases, obvious dust can be seen on the surface of the platinum mesh, and the surface of the platinum mesh is dark.

Therefore, the poor air quality is one of the reasons for the high ammonia consumption of the nitric acid plant, and the poor air quality is mainly caused by the poor filtering effect of the air filter

2. The catalyst is polluted by oil

Its disadvantage is that it is only effective for filtering ions above 10 μm, and has almost no filtering effect on ions below 10 μm

3. Cold air ammonia filtration: Domestic nitric acid plants have not yet installed cold air ammonia filters. The low-temperature gas ammonia evaporated from ammonia contains liquid droplets and unseparated oil, which increases the separation and filtration load of hot gas ammonia. After a period of use, the hot gas ammonia filter will be filtered The effect becomes worse, and a higher purification rate cannot be achieved

Affected by the principle of separation, the short residence time of the fluid in the separator, and the high flow rate, the actual output of 3-10% ammonia droplets (not including gaseous ammonia) circulates in the system, reducing the degree of ammonia purification

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