Application of Chengdu Sunwoele High Voltage VFD (Variable-frequency Drive) in the Petrochemical Industry
1. Project transformation content
1. Description of the original system
Yihua high pot induced draft fan system process:
Air blower→furnace→induced draft fan
The 4# high pot induced draft fan of PetroChina Ningxia Petrochemical Branch is arranged for a single furnace and a single machine. At present, the output of the induced draft fan is adjusted by the water truck workshop according to the boiler output and combustion conditions. The central control room adjusts the induced draft fan baffle through DCS to maintain For furnace negative pressure, the current average load of the boiler is between 90% and 95%, and the baffle opening does not exceed 30%. Due to the large redundant power in the design of the induced draft fan, and the resistance of the windshield for air volume control, which consumes electric energy, This results in high energy consumption and directly affects the economic operation of the unit.
According to the current actual operating conditions of the 4# high pot (the windshield opening is between 20-30%), in order to reduce the unit consumption of the induced draft fan, Ningxia Petrochemical Company decided to use the American Robincom company's perfect harmonic-free product provided by our company (Perfect-Harmony) series high-voltage VFD (Variable-frequency Drive) carries out frequency conversion transformation on the Erhua 4# high pot induced draft fan motor, changing the Erhua high pot induced draft fan from the original power frequency operation mode to variable frequency speed regulation operation.
2. Description of original equipment parameters
3. Description of transformation system
Selection of planned transformation system and high-voltage frequency conversion equipment
System to be modified: Erhua 4# high pot induced draft fan
Selection of high-voltage frequency conversion equipment: According to the load parameters and operating conditions provided by Ningxia Petrochemical Branch, our company plans to configure a Perfect-Harmony series high-voltage VFD (Variable-frequency Drive) for each of its No. 4 high-pot induced draft fans. .
2. Project transformation benefits
1. Power saving benefits
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(1) From the historical data of electrical microcomputer monitoring of the thermal power station of the factory, it can be seen that before the transformation, when the induced draft fan used a damper to control the negative pressure, the average power consumption at the power frequency was about 800 to 900kW, the average operating current was about 90 to 110A, and the power factor was 0.86
(2) On the day the transformation was completed, the electrical microcomputer monitoring data of the plant’s thermal power station were as follows:
Power consumption in cold state in the early morning of October 24th: P rear = 128kW, 6KV side current 13A, speed 590rpm
Power consumption in hot state at noon on October 24th: P = 86kW, 6KV side current 8.4A, rotation speed 400rpm
About half a year after the transformation was completed, the electrical microcomputer monitoring data of the plant’s thermal power station was as follows:
On April 13, the power generation load was 22.5MW and the load rate was 90%:
P rear = 324kW, 6KV side current 30.9A, speed 660rpm, power factor 0.97
(3) According to the above statistics, after the frequency conversion speed adjustment transformation of the 4# high pot induced draft fan, the average power consumption per hour is saved by about 500kW. Based on its settled electricity price of 0.315 yuan/kWh and annual operating time of 8,400 hours, its annual energy saving income It is: 0.315×500×8400=1,323,000 yuan, which is more than 1.3 million yuan.
2. Other benefits
1) Benefits to electrical equipment and the power grid: First, due to the excellent soft start/stop function of the high-voltage VFD (Variable-frequency Drive) (can start at zero speed), the impact of the starting impulse current on the motor and the power grid is greatly reduced. At present, at the induced draft fan motor site, it can be clearly felt that the motor noise has been significantly reduced, the operation is very smooth, and the vibration is extremely small. This effectively reduces motor failures, thereby greatly extending the maintenance cycle and service life of the motor, and also effectively avoiding impact loads. Adverse effects on the power grid; secondly, after the frequency conversion transformation, it can be seen from the electrical microcomputer monitoring that the current power factor of the motor is as high as 0.97, and the reactive power loss is extremely small.
2) Benefits to mechanical equipment and pipe networks: First, because the damper is fully open, the possibility of surge, turbulence and damper failure is eliminated; second, due to the unique smooth adjustment of the high-voltage VFD (Variable-frequency Drive), It greatly reduces the mechanical wear of the fan, and at the same time reduces the temperature of the bearings and bearing bushes, effectively reducing maintenance costs and extending the service life of the fan.
3) Benefits to the operating process: After using variable frequency adjustment, the negative pressure adjustment becomes fast and sensitive.
4) Benefits to the control process: The use of frequency conversion regulation further improves the automation level of equipment operation control and system operation management.