In common chemical reactions, gas is often used as a feedstock reaction gas, which is usually mixed, proportioned or diluted.
The commonly used gas distribution methods are divided into static gas distribution and dynamic gas distribution.
Static valve method
The static gas distribution method is to add a certain amount of gas raw gas into a container with a known volume, and then fill it with diluted gas for mixing. The raw gas used can be pure gas or mixed gas with a known concentration. Usually, the gas cylinder is directly connected to the reaction device that needs to be filled through the pressure reducing valve and mass flow meter. The reaction device can be a pressure reactor, reaction kettle or tube furnace. Static valve usually has simple equipment and easy operation, but it also has the following problems:
1. Due to the active chemical properties of pollutants in the atmosphere, long-term contact with the container wall may cause reaction, and there is also the phenomenon of adsorption of gas on the container wall, which will lead to inaccurate distribution concentration;
2. When the gas enters, the outlet of the reaction device should be closed. If the flow rate is not properly controlled, the pressure in the reaction device will exceed the safety condition and cause safety hazards;
3. The maximum pressure that can be achieved is limited by the gas source, so the pressure in the reaction device cannot be higher than the outlet of the gas source, and the use scope is limited, which will also cause the waste of the gas source;
4. When inflating, the pressure cannot be accurately controlled.
Dynamic valve method
Dynamic gas distribution method is the known concentration of raw material gas with a small flow rate, a certain proportion of gas distribution, continuous delivery into the gas mixing chamber, mixing in the mixing chamber, with a large flow rate, continuous output of a certain concentration of gas for reaction use. Compared with the static gas distribution method, the dynamic gas distribution method can not only provide large flow of mixed raw gas, but also obtain standard gas of required concentration by adjusting the flow ratio of raw gas and diluted gas. It is especially suitable for preparing standard gas of low concentration. Standard gas is the basis for testing methods, evaluating sampling efficiency, drawing standard curves, calibrating analytical instruments and testing quality control.
Perfectlight Technology launchedPld-dgcs05 multi-component dynamic gas distributorandPld-hgcs020 High pressure automatic gas distribution deviceTwo devices,The experimental system is designed for different reaction pressure conditions.