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How to calculate the theoretical and actual flow of roots blower for biogas transmission?

Source: Roots blower manufacturer Published on: November 22, 2021-12 Hits:

Special gas transmission uses Roots blower such as Roots blower for biogas transmission The following problems often occur: the actual air volume is always greater than the calculated air volume. What is the cause? Let's discuss with you:

The theoretical calculated flow of roots blower for biogas transmission is always greater than the actual flow:

The theoretically calculated flow is greater than the actual flow, and the influencing factors are:

First: internal leakage loss

Under the effect of the inlet and exhaust pressure difference, part of the gas in the exhaust chamber returns to the inlet chamber through the rotor gap.

Second: leakage loss

Roots blower for biogas transmission

Under the action of the differential pressure between the inside and outside of the casing, the gas leaks from the exhaust chamber of Roots blower to the outside through the shaft end clearance, or from the atmosphere to the inside of the vacuum pump.

Third: Heating effect of leakage in roots blower

The compressed and heated gas leaks into the air inlet cavity, heating the gas from the air inlet to a certain extent, increasing its specific volume and decreasing its mass flow

Fourth: Heat transfer of Roots blower

Under the effect of compression heat, the temperature of the impeller and casing will rise, and the gas from the air inlet will also rise and expand when it comes in contact with them.

Fifth: Gas pressure loss

When the gas flows, there is a certain pressure loss, which will be converted into heat and absorbed by the gas, so that the gas will rise and expand.

Among them, the first two factors directly affect the actual flow, and the third four five factors are indirect factors affecting the actual flow. In the process of flow measurement, it is difficult to distinguish the influence of the above factors.

Relation between theoretical calculation flow and pressure of roots blower for biogas transmission

At a certain speed, the flow rate slightly decreases with the increase of pressure rise (or pressure ratio), because the leakage flow rate increases with the increase of pressure rise; Under the condition of a certain pressure rise of roots blower, the flow increases with the increase of speed. The flow curves at different speeds are roughly parallel to each other, because the theoretical flow is proportional to the speed, while the leakage flow has little relationship with the speed.

The above is the knowledge of May Day: Why is the theoretical calculated flow of Roots blower for biogas transmission different from the actual flow? We wish you all a happy holiday. If you have any questions during the holiday, please contact us at 0531-83663588, and we will try our best to answer them

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