In recent years, with the country's attention to environmental protection, each has set up its own sewage treatment stations. These sewage treatment stations are relatively small in scale and treatment capacity. At the same time, in order to save treatment costs, more biochemical treatment is used.
As we all know, in the biochemical treatment system, Roots blower consumes a lot of energy, generally accounting for the total energy consumption of the whole sewage station 40% Some even more.
However, in recent years, the cost of energy consumption, which is dominated by electricity charges, has been rising. Many sewage treatment plants cannot operate normally because of high operating costs, so that the sewage treatment plants invested heavily in construction have not played its benefits. Some have tried to start to secretly discharge sewage, which has led to the deterioration of the water environment in China. Therefore, the operation of sewage treatment plants has been optimized to save costs, Reducing the treatment cost is an important means to ensure the normal operation of sewage treatment plants.
For the sewage treatment station, I think the first step is to start with the Roots blower for sewage treatment. First, let's analyze the working principle of Roots blower.
Roots blower for sewage treatment It is a positive displacement fan, and the air volume delivered is proportional to the speed. Every time the three blade impeller rotates two Impeller three For secondary suction and exhaust, compared with the two blade type, the gas pulse is less, the load change is small, and the mechanical strength is high. stay two The shaft of each horizontal line is provided with two There are three blade impellers. There is always a small gap between the wheel and the inner hole surface of the oval case and between the three impellers. Because the impellers rotate at a constant speed in opposite directions, a certain amount of gas surrounded by the case and the impeller is transported from the suction side to the discharge side. Each impeller is always kept in the correct phase by the synchronous gear, which will not touch each other, so it can be high-speed, does not need internal lubrication, and has simple structure, stable operation, stable performance, suitable for a variety of purposes, and has been used in a wide range of fields.
Usually, the Roots blower and water pump on the sewage treatment system are operated at a constant speed by the motor, and then the air volume is adjusted by changing the opening of the valve at the outlet of the blower or the water supply is adjusted by changing the opening of the regulating valve on the outlet pipeline of the water pump. The biggest feature of fans and water pumps is that the load torque is proportional to the square of the speed, while the shaft power is proportional to the cubic of the speed. Therefore, if the constant speed operation of the motor is changed to adjust the speed of the motor according to the required flow, a large amount of power can be saved. In the sewage treatment system, the main function of Roots blower is to flush oxygen for the biochemical system, so that the biochemical system has sufficient oxygen. We put an online dissolved oxygen meter in the biochemical tank, set the oxygen content required in the water on the dissolved oxygen meter, and send the data of the online dissolved oxygen meter to PLC On, by PLC Control frequency converter, and then control roots blower by frequency converter, which has obvious effect.
We know that the wind pressure of Roots blower is not limited by the fan speed, and the wind pressure can remain unchanged no matter how the speed changes. The air volume is proportional to the fan speed, namely Q=KN
Q : air volume N : indicates fan speed K : is the coefficient
It can be seen from the formula that the air volume regulation is achieved by changing the motor frequency completely by the frequency converter to achieve stepless speed change, which has the effect of adjusting the air volume. According to the lowest frequency of process fan applied on site 15HZ , usually in 35HZ Around, there are some special moments 50HZ For full air volume operation, since the biochemical system process is basically the same, the air volume regulation is basically the same in different biochemical systems, so the application of frequency conversion technology can achieve 40% About the energy-saving effect.
Roots blower is a constant torque load, and its power saving rate is proportional to the speed drop, that is N%=△N% Although the power saving rate of fans and pumps is higher than that of general fans and pumps, the power of them is larger, and as long as the aeration system in the biochemical tank is not bad, it works continuously and starts for a long time, so the power saving potential is large and the cost of power saving is high.
After the technical transformation of Roots blower for sewage treatment, the production mode of adjusting the air pressure or air volume by adjusting the size of the outlet valve in the past has been changed. The labor intensity is reduced, the adjustment is timely, and the energy consumption of a single machine is significantly reduced.
The inverter has the following advantages after energy-saving transformation of the fan:
one Improve power factor and reduce reactive power loss ;
two . The inverter control has the automatic energy-saving control function, which can automatically adjust the voltage and frequency according to the load conditions, so that the motor can operate at the highest efficiency ;
three The frequency converter has advanced magnetic flux vector control, low frequency output rated torque, and can implement powerful control on Roots blower ;
four Saving and reducing operation cost ;
five . Realize soft start and no large current impact during startup ;
six Prolong the service life of Roots fan.
In the sewage treatment system, various pumps also need energy conservation. We can use frequency converter control according to the needs of the process to achieve the purpose of energy conservation. At the same time, when installing pumps, we should also pay attention to the following points to achieve the purpose of energy conservation.
1、 Select a reasonable installation position, reduce elbows, and make the water outlet face the pool.
2、 Shorten the line.
3、 Enlarge the outlet pipe diameter.
4、 The water can be removed when it can be kept clean.
5、 Adjust the axial clearance to prevent the impeller ring and axial clearance from being inappropriate. When using, it should be adjusted according to the factory instructions of the pump.
6、 Timely remove pipe blockages. Foreign matters left in the inlet pipe, impeller or flow passage of the guide housing will reduce the water yield.
7、 Prevent the water pump from entering the air. When air is fed into the water pump, the water output will be significantly reduced, and the sealing parts should be inspected and maintained.
8、 The use of coupling direct transmission instead of flat belt can improve transmission efficiency.
9、 In some places, the bottom valve shall not be used if possible.
