Selection issues for oxygen control valves
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This post was last edited by chaohua*n on 2015-8-4 at 15:18. The oxygen supply is 800 Nm3/h (with N at 0°C and 101325 Pa); the pressure under these conditions is 1.5 MPA gauge pressure. Currently, I have a mixing tank with a pressure of 30–40 KPa. The tank has two inlets: one for introducing oxygen, and the other for adding air using a Roots blower. Oxygen is delivered over 200 meters using DN40 pipes and enters the tank; is it necessary to install a control valve to reduce the pressure before it enters the tank? The valve manufacturer said that a control valve can be used to achieve a gauge pressure of 1.5 MPa at the front end, with a pressure range of 30–60 kPa at the rear end, while ensuring that the mass flow rate remains constant; the mass flow rate will also be 800 Nm3/h, meaning it stays unchanged. Everyone, let’s see if it’s possible to achieve this. The valves provided to me are DN40-80! Waiting online, seeking help from fellow netizens
Of course, it can be achieved using a stand-alone pressure relief valve
When the pressure in the rear-end mixing tank changes, if the setting of the pressure regulator is incorrect, could it stop working?
It is not possible to determine the backpressure, as the transmission takes place through 1200 meters of pipeline, and nozzles need to be installed; the outlet pressure of these nozzles is initially designed to be 30 kPa gauge pressure.
You can try a self-acting flow control valve~~ Of course, if remote control is needed, you can use a flow regulating valve~~
It’s not called a control valve; it’s a pressure reducing valve
How is the pressure in the mixing tank controlled? If it is entirely established by the upstream 800 flow rate, it is recommended to install a pressure-controlled PIC on the tank, with the control valve PV placed on the 1.5MPA pipeline. 1.5 MPA gauge pressure at the upstream side, and 30–40 KPA gauge pressure at the downstream side. No matter which valve (or orifice plate) is installed here, it will cause blockage of gas flow; the gas flow rate depends on the upstream pressure and the size of the opening, and has nothing to do with the downstream pressure. See this post for more details. http://bbs.hcbbs.com/thread-1403267-1-1.html。 In other words, pressure control is used: the opening degree of the control valve adjusts as pressure changes in order to maintain a constant pressure in the tank, while the actual flow rate varies. If you use a PIC to control the pressure in the tank, will the tank pressure remain stable regardless of the flow rate used by downstream users, thus meeting the process requirements? If traffic monitoring is really necessary, add a flow meter upstream. Is proportional control required for O2 and air? @jiaguoyun
I have a gentle question: is it okay to mix oxygen directly with air like this? @HEJIYUER
The pressure in the mixing tank is generated by a Roots blower, which can produce 3500 cubic feet of air per minute; pure oxygen at a flow rate of 800 cubic feet is used to supply pressure to the mixer. I’m currently stuck at the decision of which type of control valve to use.
It is possible to use a self-acting pressure regulator; however, due to the oxygen environment, self-acting valves are generally not used – it is safer to opt for control valves instead.