First, the application of frequency converter in sewage treatment equipment The sewage treatment plant (activated sludge treatment method, daily processing capacity of 8000 tons) equipment is all-weather operation, and aerator and submersible pump are the core equipment of sewage treatment. The frequency converter is required to adjust the speed of the aerator blower and submersible pump.
1. Application of frequency converter on blower The blower feeds compressed air into the aeration tank through the pipeline, allowing the oxygen in the air to dissolve in the sewage to supply microorganisms in the activated sludge. When the blower is started in the power frequency state, the current surge is large, which easily causes voltage fluctuation of the power grid. However, the air pressure of the blower is constant. The air volume can only be adjusted by the number of working platforms and the outlet valve. The actual production operation is often controlled by adjusting the outlet valve. , that is, increase the pipe resistance. Therefore, much energy is wasted on the valve. With the wide application of frequency converters, the use of frequency converters with a wide range of speed, mechanical characteristics such as hard, in the fan on the application of Yaskawa F7 series inverter. Because the soft start of the inverter greatly reduces the impact on the grid when the motor is started, and during normal operation, the outlet valve is opened to the maximum, according to the requirements of the process and parameters, appropriate adjustment (via the potentiometer of the control system The speed of the motor regulates the air volume of the pipe to regulate the oxygen content in the sewage. Moreover, the closed-loop automatic control can be conveniently realized according to the signal (4-20MA) fed back by the dissolved oxygen sensor. Many cumbersome manual operations are eliminated, and there are obvious power-saving effects. The following is the statistics of the power-saving rate of wind turbines.
Three sets of inverters are used to control three fans, of which two are used and one is prepared. The power of the motor is P=55KW, and the designed air volume is Q. The no-load loss is 10% and the rotational speed is 1250 rpm. If the fan is continuously adjustable below 970 rpm, the amount of air supply required for sewage treatment is 1.5 Q per day.
(1) One frequency operation, one frequency conversion operation; full speed P0=(55-55*10%)=49.5KW
P1=55KW
P2=5.5+49.5*(50%)3=11.7KW
The total power consumption is 67KW
(2) The average supply air volume per unit is 75% for two inverters
P1+P2=5.5+(75%)3*49.5=26.4KW
The total power consumption is 52.8KW
(3) When three inverters are running, the average air supply per unit is 50%.
P1=P2=P3=[5.5+(50%)]3*49.5=11.7KW
The total power consumption is P1+P2+P3=35.4KW
It can be seen that the three fans are best when they are fully-inputted in frequency conversion. Assuming that we work 30 days a month and work 24 hours a day, at a rate of RMB 0.6 yuan per degree, scheme 3 can save about 8,000 yuan more than the other two programs.
2, the application of the inverter in the submersible pump The submergence pump start current impact and adjust the pressure / flow in a similar manner with the blower. The sudden twisting of the submersible pump during start-up and the water hammer phenomenon during sudden stoppage are often apt to cause looseness or rupture of the pipeline. Severe damage to the motor may occur, and the motor must be started/stopped to open/close the valve to reduce the impact of water hammer. This operation on the one hand, work intensity, and it is difficult to meet the needs of the process. After installing the frequency conversion governor in the submersible pump, the motor can be soft-started/soft-stopped according to the needs of the process, so that the phenomenon of torsion and water hammer can be solved. And in the case of small flow, you can reduce the pump speed, on the one hand to avoid long-term work of the pump at full load, resulting in premature aging of the motor, and the soft start of the frequency conversion greatly reduces the impact of the pump on the mechanical start . And has a significant power saving effect.
Second, the system application effect Blower and submersible pump in the sewage treatment plant after using the RIBO series frequency changer, has not only avoided many tedious manual operations, the hidden trouble factor of the security, and causes the system to be in a state of energy conservation to run at all times, Extended equipment life, better adapted to production needs. Furthermore, Yaskawa's rich internal control functions can be easily controlled with other control systems. From the half-year operation, it worked well. Therefore, the use of frequency converters in sewage treatment plants or similar systems should have very good promotional value.
