Which is better for the given operating conditions: a control butterfly valve or a control V-ball valve?
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Which is better for the given operating conditions: a control butterfly valve or a control V-ball valve? The reliability under this operating condition is the main consideration; other factors can be ignored! ! ! The catalytic unit, which is used to regulate the pressure in the settler, is installed on the outlet pipeline of the distillation tower. Due to space constraints, only V-ball valves and butterfly valves can be used. The operating temperature is 100 degrees, the pressure is 0.1 MPa, and the medium flowing through the pipeline is oil and gas (with slight coking). Regulation is required frequently; adjustments need to be made every about 2 seconds in automatic mode. The valve opening range normally does not exceed 3% of the full stroke.
Such frequent occurrences mean it’s essentially in constant vibration; it’s recommended to use V-type ball valves, as they are more reliable
Could you explain a bit why V-ball is more reliable?
The V-shaped cut core exerts a shearing force between it and the metal valve seat, making it particularly suitable for media containing fibers, tiny solid particles, slurries, etc. ◆This valve features precise adjustment and reliable positioning; its flow characteristic is approximately equal percentage, with a wide adjustment range of up to 100:1.
If I had to choose, well I don’t really know either; usually I would pick V-ball or eccentric rotation.
An eccentric ball valve can be used, but I don’t understand why the valve position in your case is so small; in a normal design, the valve position should be around 50
I’d like to ask about the process parameters: what is the valve resistance ratio? It is only by taking the square root of the valve resistance ratio and multiplying it by the actual adjustable range that the true adjustment range can be determined; a such small opening angle makes it very difficult to make adjustments
The degree of coking accumulation; if the accumulation is severe, is the shearing action of the ball valve still effective? What about requiring no internal leakage in the valve? In principle, it is easier to fully close a ball valve. Be careful with three-eccentric butterfly valves to avoid failure to close due to coking. If only the flow rate is adjusted, the eccentric rotary valve is least prone to coking.
What is the caliber? Based on your description, the outlet control valve of this distillation tower is not adjusted during normal production here; it is only adjusted when starting up or shutting down the plant.
V-type ball valves are good. It has a shearing function and is not prone to coking. The service life of V-type ball valves is longer than that of triple-eccentric hard-sealed butterfly valves. The valve seat of three-eccentric hard-sealed butterfly valves is prone to coking, which causes internal leakage in the butterfly valve; moreover, the cost of repairing or replacing the valve seat is high. Due to the frequent opening and closing of the valve, it is recommended to choose a valve stem material that is wear-resistant and has high mechanical strength.