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Gas flow, did you set it right?

In the study of environmental governance, there will be a need for gas to participate in the reaction in the form of flow, mainly including photothermal catalytic CO2 hydrogenation reaction, photothermal catalytic methane reforming reaction and photocatalytic gas pollutant degradation reaction.

In the process of flow reaction, the reaction gas is always in the flow state, so it is necessary to accurately adjust the gas flow to participate in the reaction stably in the experimental reaction process.

At present, among the products sold by Perfectlight Technology, the main products of flow reaction devices involving gas participation are as follows: 

1.Plr-ptsr II photothermal catalytic reaction instrument, mainly suitable for mobile phase gas-solid photothermal catalytic reaction, such as photothermal catalytic CO2 hydrogenation, photothermal catalytic methane reforming and photothermal catalytic CO2 reduction reaction;

2. Plr-gspr normally pressurized gas-solid photocatalytic reaction system, mainly suitable for mobile phase gas pollution degradation reaction, such as photocatalytic degradation of NOx, photocatalytic degradation reaction of VOCs; 

3. Pld-dgcs05 multi-component dynamic gas distributor is mainly suitable for the precise control of gas mixing and gas flow.

图1. 流动相光催化反应装置.jpg

FIG. 1. Mobile phase photocatalytic reaction device

Plr-ptsr II photothermal catalytic reaction system, PLR-GSPR constant pressure gas-solid photocatalytic reaction system and PLD-DGCS05 multi-component dynamic gas distributor all adopt mass flow controller. 

Mass Flow Controller (MFC) is a device that can accurately measure and control the gas Flow. It not only has the function of Mass Flow meter to measure the Flow, but more importantly, it can automatically control the gas Flow through the Flow setting as required. The measured value does not need temperature and pressure compensation. 

The unit of flow for mass flow controllers is generally expressed in Standard Cubic rectification Per Minute (SCCM) and Standard Liter Per Minute (SLM), that is, Standard milliliters Per Minute or Standard liters Per Minute. 

Under different service conditions, the indicated flow is 0℃, 101.325 kPa flow. 

Mass flow controller will be calibrated before delivery, generally N2 is used as the calibration gas. However, in the process of the experiment, the raw gas may be other gases, so there will be a deviation between the set flow rate and the real flow rate, which will affect the experimental results. 

93/5000 For example, the raw gas of the experiment is CO2, the gas calibrated by the mass flow controller is N2, and the required flow rate of the experiment is 100 SCCM. If the set flow rate is still 100 SCCM, the real FLOW rate of CO2 is 73.7 SCCM, less than the required flow rate of the experiment.

Formula (1) can be used to convert the set flow rate to the real flow rate:

气体流量,你设置对了吗?.jpg

Calibration coefficients of common gases are shown in Table 1

流动相反应实验中,气体流量的控制表格.jpg

Before the experiment, be sure to check the calibrated gas type of the mass flowmeter, refer to Table 1, and substitute the flow used in the experiment into formula (1) to calculate the set flow rate. 

During the experiment, if the raw gas is pure gas, formula (1) can be used to calculate. If the raw gas is mixed gas, the correction coefficient of the mixed gas should be calculated by formula (2) and then substituted into Formula (1) for calculation.

气体流量,你设置对了吗?.jpg

C1, C2, and C3 are the percentages of gases in the mixture.

For example, the mixed gas is 20% H2 and 80% CO2, the mass flow controller calibration gas is Ar, and the required flow rate of the experiment is 200 SCCM. The experimental set flow rate is calculated as follows:

气体流量,你设置对了吗?.jpg

Set the flow rate to 361.2 SCCM.


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