General Situation Of Pneumatic Angle Seat Valve In Alumina Production

Pneumatic angle seat valve is a kind of control valve widely used in modern industrial production, with long service life, sensitive and reliable operation, and economic investment. It is suitable for water, liquid, neutral gas, steam, slightly corrosive gas, and liquid medium. Strengthening the research on the application of control valves in production is of great value for prolonging the service life of the valve, reducing the failure rate, ensuring the stability of the production process and product quality. As we know, the globe control valve with pneumatic actuator and smart positioner is a kind of control valve which is popular among the world. And it also needs valve actuator accessories to make it better. In the production process of alumina digestion process in our plant, due to the complexity of the control object and the bad site conditions, valve failures occur frequently, which not only seriously affects the stable operation of production, but also even causes safety accidents. This paper only discusses the application of the control angle seat valve, hoping to be helpful to colleagues.

Main problems in the application

The slurry steam in the alumina digestion autoclave tank is cooled and condensed into water in the condensing tank. It flows through the angle seat valve and is stored in a good water tank. After detection and analysis by the conductivity meter, it is distributed to the thermal power plant or hot water station for recycling.

The main causes of valve failure are valve core and air source.

1. Valve core failure

Because there are a lot of residues and foreign matters in the condensate of the valve body control medium, the erosion and wear of the valve core are great, resulting in the wear deformation of the valve core. The poor wear resistance of the valve core is an important reason for the failure of the control angle valve. Usually, the fail safe electric actuator may be helpful to deal with those failures.

2. Air source failure

Due to the great vibration of the site environment, the copper gas pipe in use is easy to break and damage under the action of strong vibration, which causes the control valve not to act. At the same time, the air source used by the control valve is easy to be blocked due to impurities, and the air pressure is insufficient.

3. Valve leakage

The sealing gasket was not replaced in time, resulting in valve leakage.

Methods and measures adopted

1. According to the requirements of various performance indexes and field process conditions of the angle valve currently used like angle seat check valve, the special valve core with good wear resistance and erosion resistance is used to replace the original valve core, and the internal structure of the valve core is improved. The wear resistance can meet the requirements of the production cycle, and it is not easy to block.

2. The gas source pipe of the angle valve is changed from the original copper gas source pipe to the metal-plastic hose with pressure resistance, softness, and seismic resistance meeting the requirements; at the same time, the purification and filtration device is added to the gas source to ensure that the gas source pressure is stable and meets the requirements.

3. Timely replace the gasket in the maintenance cycle to ensure that the gasket meets the installation standard, the pressure test is qualified, and the gasket is not used beyond the time limit. For example, if you have an angle seat piston valve, you should keep it in a good condition. By doing this, you will spend some money. Of course, angle seat valve price is also a source of expenditure.

By taking the above measures, the control angle valve-like pneumatic control valve can not only meet the needs of production in terms of control effect and pressure reduction performance but also greatly increase the stable operation cycle without failure, which effectively ensures the stable operation of production. The fact shows that as long as the patient and careful analysis and study of the production site conditions, and take effective countermeasures, it can greatly reduce the failure rate of field equipment, which has a certain reference value for the design and selection of control valves in the future.