Consequence analysis of poor Performance of one suction tower demister

1. Corrosion and leakage of the outlet pipe of a suction tower

When the first suction tower demister with acid is serious, the outlet pipe of the first suction tower is easy to be corroded and leak. Even if there is a small amount of leakage, because the leaked smoke is mixed with small sulfuric acid fog and dispersed to the entire plant, the personnel located under the wind direction of the suction tower will feel the hot face, seriously affecting the on-site operating environment and the safety of on-site operators, resulting in increased safety risks. 【1】

2. Cold bundle leakage, resulting in a decrease in the total conversion rate

A suction tower mist eliminator brings acid into the downstream intermediate hot and cold heat exchanger, which will cause corrosion, perforation and leakage (internal leakage) of the intermediate hot and cold heat exchanger tube bundle, and the internal leakage of the intermediate hot and cold heat exchanger will inevitably lead to a decrease in the total conversion rate. 【1】

3. The principle of pulverization and scarring of catalyst at the top of the first layer of converter is the same. When the performance of the demister of a suction tower is poor, the catalyst at the top of the four layers of the downstream converter is easy to powder and scar, and the resistance of the four layers will rise rapidly, affecting the operating load of the acid making device, resulting in an increase in operating costs. 【1】

4. Self-heat balance affecting secondary conversion

Many users check and plug leaks during maintenance, but they fail to fundamentally solve the problem of acid in the upstream mist eliminator. After the tube bundle of the intermediate heat exchanger is blocked several times, the heat exchange area is reduced, and the heat exchange of the intermediate heat exchanger will decrease accordingly, resulting in the difficult to maintain the inlet temperature of the bed after the conversion and the self-heat balance of the secondary conversion. 【1】

5. The execution of conversion temperature is affected, and the total conversion rate is reduced

The inlet temperature of the bed after conversion is difficult to maintain when the cooling heat decreases. When the bypass valve of the second heat exchanger (that is, the intermediate heat exchanger) is closed, the heat exchange of the second heat exchanger increases, and the temperature of the fourth layer inlet of the converter will rise, but at the same time the temperature of the third layer inlet of the converter will decrease. When the bypass valve of the second heat exchanger is opened, the heat exchange of the second heat exchanger will decrease, the inlet temperature of the third layer of the converter will increase, and the inlet temperature of the fourth layer of the converter will decrease. The control of the subsequent bed inlet temperature under the above conditions is often one thing and the other. It should be noted that the control of bed inlet temperature after conversion involves the conversion temperature regime; The conversion temperature regime is extremely important for the conversion operation of sulfuric acid plants, and if it is not followed, it will inevitably affect the total conversion rate. 【1】

6. Reduced driving rates and increased safety risks

A suction tower mist reducer with acid will cause corrosion of downstream pipelines and equipment, and correspondingly the operating rate of sulfuric acid equipment will inevitably decline. The repeated sealing of the downstream intermediate heat and cold exchanger will increase the number of operations in the confined space and increase the safety risk. 【1】

Consequence analysis of poor Performance of mist eliminator in two suction towers

1. The poor performance of the second suction tower demister will also be accompanied by acid. Although the influence range of the second suction tower demister is relatively small when the performance of the second suction tower demister is poor, its importance is self-evident because the second suction tower demister involves the standard emission of acid fog in the tail gas. 【1】

2. Exhaust acid fog and particulate matter exceed the standard

When the fog eliminator of the second suction tower carries more acid, the acid fog at the exit of the second suction tower is often significantly exceeded. It should be pointed out that due to the small particle size and the large surface tension of the acid fog particles from the second suction tower, the proportion of the above submicron acid fog removed after washing by the tail suction tower is not high. For the fiber demister made by filling type, when the acid making device is running, because the fiber bed of the demister has a certain amount of acid, the fiber bed sinks under the action of gravity and causes a short circuit in the upper part of the demister, and the exhaust particles are easy to exceed the standard. 【1】

3. Increased absorption consumption of tail tower

For the tail absorber of the solvent absorption principle, the acid of the second absorber mist eliminator will cause an increase in the sulfate content of the solvent, resulting in an increase in the absorbent consumption of the tail absorber. At present, the latest design of the sulfuric acid exhaust ion liquid absorption tower is equipped with electric demister in front of the tower and behind the tower. The purpose of the electric demister in front of the tower is to reduce the solvent consumption, and the purpose of the electric demister in back of the tower is to ensure that the acid fog emission reaches the standard. 【1】

4. Driving rate is down

The two suction tower mist reducer with acid causes corrosion and leakage of downstream pipelines and equipment, and the above leakage needs to be stopped for treatment, and the corresponding operating rate of the sulfuric acid device will also decrease. 【1】