We have got butterfly pressure control valves inslalled in natural gas metering skid, high pressure (74 bars).
The purpose of this query is to remove kicks on these valves and to ensure a smooth continuous control.
The investigation shows that kicks are noticed when the control is in auto mode with an important differential pressure (> 4 bars) through the valve. This happen, when the outlet pressure is low ( about 62 bars) and valve opening is low ( about 25%).
In such situation, with a high differential pressure (4 bars), the valve position does not respond to 1% output variation.

Do you recommand any solution ? other valve type ?

Hafedh Ghodhbani

 

a butterfly valve is a very poor option in any control application. basic butterfly valves deliver 80% flow variation over 20% valve opening.
If you must use a butterfly, then best would be to use a characterised disc with a very smart digital positioner. It is possible to insert a characterising disc on the upstream side of the butterfly valve to change its flow characteristics, this provides a low cost option because you can still use your existing valves.
but use a smart positioner.

A better option would be a rotary plug valve with equal percentage flow characteristics and with the smart positioner.

regards

 

Hi

The butterfly valves are very poor for using in natural gas, I recomend you use the Ball valves like worcester, with same pneumatic actuator.

regards

 

dear sir,
How to prevent kick backs control in plug seat type control valve with high line pressure up to 100 bar, plug dia is 2 inch?