Energy-saving principle of variable frequency constant pressure air supply system

Working principle of fan frequency conversion energy-saving transformation plan

First, the principle of energy saving of variable frequency constant pressure air supply system

1. Principle of constant voltage supply air frequency control system

Note: The fan in the figure is the output link, and the speed is controlled by the inverter to realize variable air volume constant pressure control. The inverter accepts the signal of the PID regulator to control the speed of the fan. After the controller combines the given signal and the feedback signal, it is adjusted by the PID to output the running frequency command to the inverter. The pressure sensor monitors the tuyere pressure and converts it to control its acceptable analog signal for adjustment.

2 , the system works

The variable frequency speed regulation constant pressure air supply control is finally realized by adjusting the fan speed, and the fan is the air supply execution unit. The constant wind pressure can be determined by the characteristics of the fan. The characteristics of the fan are shown in the figure below. Diagram, the abscissa for the fan air volume Q, the ordinate is the pressure P. EA is a constant pressure line, n1 , n2 ... nn is the air volume-pressure characteristic at different speeds. It can be seen that at the speed n1 , if the opening degree of the control valve is such that the air volume is reduced from QA to QB , the pressure will reach the point B along the n1 curve , and it is obvious that the air volume is increased while the pressure is increased. If the speed is from n1 to n2 , the air volume reduces QA to QC , and the pressure does not change. It can be seen that under a certain range, the wind pressure can be kept constant, and the wind pressure can be adjusted without changing the wind pressure. This characteristic shows that the constant pressure air supply can be completed by adjusting the fan speed, changing the air pressure, changing the air volume, and stabilizing the pressure on the constant pressure line.

Second, 250KW fan frequency conversion energy-saving transformation program and function

1. Current status of fan operation

There is one existing fan, the supporting motor is 250KW , the working voltage is 380V , the current is 460A . Now the valve is used to control the supply air volume and pressure. This type of adjustment is inconvenient and wastes a lot of electrical energy, which can easily cause damage to valves and fans.

After years of energy-saving renovation of pumps and fans in the chemical and tire industries, Bihai Qingyun has accumulated rich experience and strong technical strength.

2 , transformation plan

Now we use a 280KW inverter to control a 250KW fan.

3 , system function

A. The wind pressure is arbitrarily set, the wind pressure is stable and there is no fluctuation.

B. Soft start soft stop, no impact on the power grid, no need for power capacity expansion

C. Extend the mechanical life of the fan

D. Phase loss, undervoltage, overcurrent, overload, overheating and stall protection

E. Saving energy, investing in recycling fast

Third, the supply of wind turbines using frequency conversion energy-saving analysis

1. Current actual operating power ( I real = 350A )

P Yun = √ 3UICOS ω = √ 3 × 380 × 350 × 0.85=196kw

W=196×320×24=1505280kwh

Note: Calculated by 320 days a year

2 , automatic speed control energy saving

A theoretical basis

Because the fan is a typical square torque load type,

Therefore, its power (shaft power), torque (pressure), and speed (air volume) satisfy the following relationship (similarity theorem):

Shaft power P = P = QH

Q ' /Q=N ' /N then Q ' =QN ' /N

P ' /P=(N ' /N)3 then P ' =P(N ' /N)3

Asynchronous motor speed formula n=60f(1-s)/p

Where: N , Q , H , P - rated speed of the fan, air volume, shaft power

N ', Q ', H ', P '—— rated speed, water volume, shaft power of the fan after speed regulation

B benefit analysis

According to the load situation of your factory (the damper opening is 80% ) and our company's experience, it is estimated that the actual running speed of your plant is 0.7~0.94 times of the rated speed , that is, the frequency varies between 35HZ~47HZ . To ensure the reliability and accuracy of the data, we take f=45HZ for calculation:

P'=(45/50)3×196=142kw

W'=142×320×24=1090560kwh

Power saving is W section = 1505280-1090560 = 399840kwh

Economic benefit: 399840 × 0.60=248832 yuan

Note: The electricity fee is calculated at 0.6 yuan per degree .

Fourth, the characteristics of the inverter

1. With super protection function - protection against over current, over voltage, short circuit, grounding, under voltage, overload, overheat, phase loss and external alarm

2 , the working environment temperature is -10 degrees to 40 degrees , humidity 95%

3. The overload capacity of the inverter is 120% , and the overload time is 1 minute.

4. When the inverter is running under the maximum load, the noise at the motor 1m is not more than 65dB, and the motor has no obvious vibration.

5 , the frequency converter has strong resistance to power supply and good electromagnetic compatibility, no electromagnetic influence and impact on nearby instruments and meters

6 , the inverter performance is excellent, long-term stability, trouble-free work

The above information is provided by Bihai Qingyun purification, please indicate the source if you need to reprint.