目前市場上的羅茨鼓風(fēng)機多為三葉式。三葉羅茨鼓風(fēng)機采用兩組三葉葉輪，每轉(zhuǎn)動一次完成 3 次吸氣和排氣。它屬于容積式風(fēng)機，是一種定容旋轉(zhuǎn)的氣動力機器，具有結(jié)構(gòu)簡單、性能穩(wěn)定的特點。

　　At present, most Roots blowers on the market are three bladed. The three bladed Roots blower uses two sets of three bladed impellers, with each rotation completing three suction and exhaust operations. It belongs to the positive displacement fan, which is a fixed volume rotating pneumatic machine with the characteristics of simple structure and stable performance.

　　羅茨鼓風(fēng)機選型技巧

　　Selection Techniques for Roots Blowers

　　1、挑選

　　1. Select

　　在為污水處理廠挑選羅茨鼓風(fēng)機時，相關(guān)產(chǎn)品樣本上顯示的是其在標準進氣狀態(tài)下的性能參數(shù)。但羅茨鼓風(fēng)機在實際使用中并非處于標準狀態(tài)，當(dāng)使用環(huán)境的溫度、大氣壓、海拔高度等條件不同時，風(fēng)機的性能也會隨之改變。因此，產(chǎn)品樣本上的性能參數(shù)不能在設(shè)計和挑選時直接采用，而是需要根據(jù)實際使用狀態(tài)，將風(fēng)機的性能要求轉(zhuǎn)換為標準進氣狀態(tài)下的參數(shù)后再使用。

　　When selecting Roots blowers for sewage treatment plants, the performance parameters displayed on the relevant product samples are under standard intake conditions. However, Roots blowers are not in a standard state in practical use. When the temperature, atmospheric pressure, altitude and other conditions of the operating environment are different, the performance of the blower will also change accordingly. Therefore, the performance parameters on the product sample cannot be directly used in design and selection. Instead, the performance requirements of the fan need to be converted into parameters under standard intake conditions based on actual usage before use.

　　2、壓力

　　2. Pressure

　　容積式羅茨鼓風(fēng)機的排氣壓力并不由其自身決定，而是由風(fēng)機排出氣體后裝置的情況，即所謂的 “背壓” 來確定。曝氣鼓風(fēng)機具有強制送風(fēng)的特點，羅茨鼓風(fēng)機銘牌上標注的排氣壓力是其額定排氣壓力。實際上，只要強度和排氣溫度允許，羅茨鼓風(fēng)機既可以在低于額定排氣壓力的任意壓力下工作，也能在高于額定排氣壓力的情況下運行。

　　The exhaust pressure of a positive displacement Roots blower is not determined by itself, but by the condition of the device after the fan exhausts the gas, known as the "back pressure". The aeration blower has the characteristic of forced air supply, and the exhaust pressure marked on the nameplate of the Roots blower is its rated exhaust pressure. In fact, as long as the strength and exhaust temperature allow, Roots blowers can operate at any pressure below the rated exhaust pressure or above the rated exhaust pressure.

　　對于污水處理廠而言，排氣系統(tǒng)產(chǎn)生的背壓是管道系統(tǒng)壓力損失值、曝氣池水深與環(huán)境大氣壓力的總和。

　　For sewage treatment plants, the back pressure generated by the exhaust system is the sum of the pressure loss value of the pipeline system, the water depth of the aeration tank, and the ambient atmospheric pressure.

　　3、風(fēng)量（需氧量）

　　3. Air volume (oxygen demand)

　　在計算污水處理需氧量時，得出的結(jié)果是標準狀態(tài)下所需氧氣的質(zhì)量流量 qm（kg/min），之后再換算成標準狀態(tài)下所需空氣的體積流量 qv1（m/min）。如果羅茨鼓風(fēng)機的使用狀態(tài)并非標準狀態(tài)，比如在高原地區(qū)，空氣密度和水分含量會發(fā)生變化，此時羅茨鼓風(fēng)機提供的風(fēng)量流量雖與標準狀態(tài)相同，但供給空氣的質(zhì)量流量會有所下降。

　　When calculating the oxygen demand for sewage treatment, the result obtained is the mass flow rate qm (kg/min) of oxygen required under standard conditions, which is then converted into the volume flow rate qv1 (m/min) of air required under standard conditions. If the usage state of the Roots blower is not standard, such as in high-altitude areas, the air density and moisture content will change. At this time, although the air flow rate provided by the Roots blower is the same as the standard state, the mass flow rate of the supplied air will decrease.

　　4、冬夏的區(qū)別

　　4. The difference between winter and summer

　　挑選風(fēng)機時，要留意其送風(fēng)量的變化規(guī)律。對于同一臺羅茨鼓風(fēng)機，冬夏兩季的體積流量不會改變，但由于空氣密度不同，質(zhì)量流量會有所差異，也就是供氧量不同。這是因為冬季氣溫降低，空氣密度增大，所以風(fēng)機供給的干燥空氣質(zhì)量流量比標準狀態(tài)下有較大增加，進而使供氧量增多。

　　When selecting a fan, pay attention to the variation pattern of its air supply volume. For the same Roots blower, the volumetric flow rate in winter and summer will not change, but due to different air densities, the mass flow rate will differ, that is, the oxygen supply will be different. This is because the winter temperature decreases and the air density increases, so the dry air mass flow rate supplied by the fan is significantly increased compared to the standard state, thereby increasing the oxygen supply.

　　因此，在生產(chǎn)運行過程中，需要針對這種變化及時調(diào)整設(shè)備，讓羅茨鼓風(fēng)機的充氧能力與實際運行中的需氧量相匹配。對于羅茨鼓風(fēng)機來說，使用變頻器通過改變風(fēng)機轉(zhuǎn)速來調(diào)節(jié)送風(fēng)量，是一種經(jīng)濟實用的方式。

　　Therefore, in the production and operation process, it is necessary to adjust the equipment in a timely manner to match the oxygenation capacity of the Roots blower with the actual oxygen demand during operation. For Roots blowers, using a frequency converter to adjust the air supply by changing the fan speed is an economical and practical way.

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