In this article, we will learn four types of method to prevent or to reduce control valve cavitation. To understand and predicting cavitation in control valve is essential.
Cavitation can cause a lot of damage to the valve body, thus increasing downtime and cost too. To reduce cavitation is necessary.
In my old article, I discussed problem occur in the control valve. Click on a link to know more about it.
In this article, you will gain knowledge on how to reduce cavitation in the control valve, anti-cavitation valve, choked flow in the control valve, how to sustain cavitation in the control valve, how to curb control valve cavitation.
There are four types of method by using them we can reduce cavitation.
1. By preventing Flashing
2. By sustaining the Flashing
3. Cushion with gas.
4. By reducing velocity
Let discuss each one by one,
1. By preventing Flashing
- We know that flashing can occur when pressure falls below vapor pressure and can never recover again.
- If we somehow manage not to fall vanacontracta pressure below vapor pressure for the liquid, which will prevent flashing and cavitation will never occur. so what to do?
- Use cavitation control valve trim.
- Select a valve type we have very low-pressure recovery rate.
- Decrease the liquid pressure which will help to reduce the vapor pressure
- Use anti-cavitation trim. so, it will provide multistage pressure drop as the fluid passes through the trim. Due to the involvement of multistage cavitation trim, the graph looks as shown in the below figure.
- One more way to reduce cavitation is to use cage- guided valve trim which contains multiple small holes which helps to reduce cavitation.
2. By sustaining the Flashing.
- Now, to sustain flashing means we have to use such a control valve with less pressure recovery rate due to that when control valve experience flashing pressure will never recover. It will remain in flashing state.
- This option is not that good as flashing also not good for control valve but it is better than cavitation.
- In the process, if we don't have many options we can go with this option.
3. Caution with gas.
- In some process, non-reacting gas is injected into the liquid stream to provide cushioning within the cavitation region.
- The presence of a non-condensible gas bubble in the liquid system disturbs the microjet pathways, helping to dissipate energy before striking on the walls.
4. By reducing velocity
- One more way to reduce cavitation is to reduce the velocity of flowing fluid. by reducing velocity pressure drop will reduce, thus pressure will not drop below vapor pressure.
These above-mentioned types are used to reduce control valve cavitation. If you have any question then put down in the below comment section. Feel free to ask.
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