The difference between winter and summer in the selection and operation regulation of roots blower:

According to the theory of fluid mechanics, the flow process of gas will be accompanied by loss. For example, after the gas flows through the throttling device, the pressure of the gas flow will be reduced accordingly, that is, they will lose the useful work of the fan. Because all this happens in the process of the fan conveying gas, it wastes the energy of the fan.

The working point of Roots blower is the intersection of the performance curve of the blower at a certain speed and the resistance characteristic line of the pipe network. The actual operation of the fan does not always stay at the design operating point. It will change with the user's demand or the change of external conditions, that is, the fan actually works under variable conditions. In order to make the air pressure or air volume of the fan reach a certain target value, it is necessary to artificially control the fan or pipe network, also known as regulation. Through effective regulation, it can not only meet the requirements of production on flow or pressure, but also maximize energy saving under the condition that the fan can work stably. In short, the purpose of regulation is to meet performance requirements, expand (stabilize) working conditions, achieve energy conservation and prevent surge.

Different adjustment modes of fans can achieve the same purpose, but the energy-saving effect is different.

According to theoretical analysis and practical proof, the following four conclusions can be drawn.

1. For Roots blower and compressor, outlet throttling regulation consumes the most power. Although the relative flow Qr (the ratio of actual flow Q to design flow Q0) decreases, the power also decreases accordingly. For example, when Q=0.65 Q0, the corresponding power is reduced to about 80% of the original, but compared with other adjustment methods, the energy consumption still ranks first.

2. If the relative flow changes little (or the regulating depth is small), the power consumption of several regulating methods is not different. That is to say, the regulation mode has little impact on the energy saving effect, even does not save energy, but consumes more power due to the existence of the regulation device (such as hydraulic coupler).

3. In general, the greater the adjustment depth, the more significant the energy-saving effect. Therefore, it is necessary to carefully select the adjustment mode in order to obtain the maximum benefit.

4. The speed change regulation curve is close to the ideal curve. Therefore, the variable speed regulation mode is superior, especially the energy-saving scheme of variable frequency motor speed regulation is the best, but it needs to add a variable frequency device. It is recommended to use frequency conversion speed regulation for medium and small capacity; Due to the high price of high-capacity and high-voltage variable frequency speed regulation device, it is necessary to make a comprehensive comparison and decide whether to accept or reject it according to the specific situation. In a word, it is necessary to consider not only the regulation performance, but also the initial investment, reliability and economy of equipment, and comprehensively evaluate the advantages and disadvantages of the regulation mode.

For the selection of roots blower, attention shall be paid to the change law of air supply flow of the blower. For the same blower, its volume flow will not change in winter and summer, but it will change due to the different air density and mass flow, that is, the oxygen supply will be different. This is because the temperature in winter decreases and the air density increases, so the mass flow of dry air supplied by the fan increases significantly compared with the standard state, resulting in an increase in the oxygen supply. From the actual measurement of operation, the dissolved oxygen in the aeration tank in winter is 1~3mg/L higher than that in summer every year.

Therefore, in the process of production and operation, it is necessary to adjust the equipment in time according to this change, so that the oxygen filling capacity of roots blower can adapt to the actual oxygen demand in operation. For Roots blower, it is economical and practical to use frequency converter to adjust the air supply volume by changing the fan speed.