Does the quick on/off operation of the control valve have any requirements regarding the control gas?
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The quick opening and closing of the control valve (with an opening time of less than 100 ms and a closing time also of less than 100 ms) requires specific conditions regarding the instrument air; the normal pressure for instrument air is 7 kilograms. Is it necessary to install an instrument air buffer tank? The quick opening and closing are required by the process in order to achieve the desired results. What is a basic prerequisite for rapid valve opening? It is necessary that there be sufficient volume and pressure of control air Let’s discuss whether buffer tanks are needed for such valves
It is preferable to have pipes or nozzles for air supply and exhaust that are large enough; otherwise, it is a problem related to the design of the cylinder.
I think 7 kilograms of pressure is sufficient; the cylinder should have a specified pressure rating, and increasing the diameter of the pipe supplying air to the gauge will do
The valve switching speed is independent of whether a gas tank is present or not. Gas cylinders are related to the following issues: FC/FO valves, gas circuit design, whether the actuator is double-acting or single-acting, and process and safety requirements. In most cases, it only relates to whether it is double-acting or single-acting. The valve opening speed is related to these factors: valve size and stroke length, pressure and differential pressure, actuator speed, air supply pressure, etc.
A pressure of 7 kg/cm2 is sufficient; the key is to increase the air volume, and a pneumatic speed booster can be used to connect a 1/2 inch pipe directly to the valve cylinder.
Installing a buffer tank ensures that the instruments can function properly in cases of insufficient gas supply. Whether installation is necessary should be determined based on usage conditions and process requirements. While there are better options, they come with increased costs and more maintenance needs. Moreover, gas cylinders are considered special equipment, and thus must be managed as such.
I’m not sure, but in Shell’s process, there are 24 sets of backflow valves on the fly ash filter; these valves open and close intermittently at a certain frequency, with the switching time being less than 100 ms. The manufacturer requires that an instrument buffer tank be added to these 24 sets of backflow valves, and this buffer tank is pressurized using high-pressure nitrogen. Why is this buffer tank needed?
Just add an air filter pressure reducing valve, that’s it