Grinding station has an annual output of 1 million tons of cement production line, the initial engineering design precipitator dust collection fan is running at constant speed, the air volume control to control the degree of opening tailgate rely. Considering changes in production and variety of changes in the yield (particle fineness of the different cement products), it requires a different amount of wind to meet process requirements. If using baffle regulation, not only poor control precision, but also on the tailgate closure to reduce the amount of wind, small changes in motor output, resulting in a lot of energy is wasted. In order to improve processes, reduce energy consumption, cement dust collection designers decided to use the fan frequency control to adjust the air flow is determined by collecting the inverter to change the fan speed to achieve. A large number of users through investigation and evaluation, the final selection of a high-voltage inverter Hunan Branch Electric Co., Ltd. (Model CSHF-550/06-A) drive collecting fan.
Second, the site process Introduction
1, the cement production process
Cement production steps can be divided into the following eight steps:
Grinding raw material for extraction (mining) crushing raw materials storage and pre-homogenization of raw materials (mill) raw materials are calcined and storage (raw materials through the cyclone preheater kiln and then into the baking material, calcination mature material) cement grinding (based on the quality of cement, mixed with other chemical raw material grinding).
Grinding cement storage and transportation process in which materials are:
Disc is rotated by the motor reducer drive, the central disc material falls from the discharge port, and move by rolling the roller to the edge of the disc under the effect of centrifugal force, the material crushed departure disc is brought to speed up the airflow and one vertical mill separator, the separator through the meal after returning to the disc, re-grinding; grinding the powder into the air, down to collect dust collection device system.
Collecting fan speed (precipitator air volume required) is mainly determined by the inner pipe mill process conditions (yield and powder fineness).
2, the main equipment of cement grinding system table :( a)
Device Name Specification Main Performance Motor Power (kW)
Roller press RP120-80 roll diameter 1200mm,
The effective width of 899mm 2 × 500 kW
∮4.2 × 11.5 tube mill capacity of 120t / h 2800 kW
High efficiency separator XWS40 processing capacity of 150 t / h 220 kW
LPM2X70 bag filter air volume 157000m3 / h
Ventilator R6-2X40No15.57 air volume 160000 m3 / h,
Wind pressure 7300Pa 450 kW
3. The cement production process diagram
Third, the dust collection fan system control program
1, the main circuit scheme
How it works: a drive configured as a drag that one inverter drives one motor. The high-voltage line terminal directly connected to the 6kV voltage level of the main power supply, the output side is connected directly to the motor. High voltage circuit breaker QF1 site for users, in order to achieve the inverter fault protection, the inverter and QF1 closing and opening the circuit to achieve chain, only the inverter control system normally allowed QF1 closing, while the inverter is heavy fault tripped QF1.
2, the control loop scheme
According to user requirements, the drive signal can be adjusted according to user feedback pressure fan pressure, you can also throttle the user's opening and closing linkage.
Inverter control cabinet of "local control / remote control" selector switch, you can easily select local operation or remote operation, the inverter support MODBUS, PROFIBUS, TCP / IP protocols and the hard-wired connections to remote operation, this system set with users in the control room DCS hard-wired connection. That DCS sent to the drive to start, stop command and frequency reference signal all the way, the drive back to the DCS, "ready", "Run", "Alarm", "Fault" and four digital signal "motor speed", " motor current "two analog signals.
Inverter schematic diagram is as follows:
3, the main technical parameters
No. specification Unit Parameter Remarks
1 using standard Q / CP BLH003-2004
Type 2 and Type CSHF-550-06-A
3 Manufacturer and Origin Hunan Branch Electric Co., Ltd.
A fourth aspect of multi-level modules in series, AC-DC, high way
5 pairs of motor squirrel-cage induction motors general requirements
6 Rated input voltage / permissible range kV 6kV ± 15%
7 system input voltage kV 6kV
8 Rated input frequency / permissible range 50Hz ± 10%
9 sensitivity to voltage fluctuations of + 15% to -35%
10 Inverter efficiency> 0.98
11 harmonic input current <4%, the output current <2%
12 reliability (mean time between failures) H 20000 Xiaoshi
13 input side power factor> 0.95 (> 20% load)
14 multi-level sinusoidal PWM control mode control
15 controls the power supply external 220V ± 10% AC, 3kVA,
220V ± 10% DC, 3kVA
16 UPS type, capacity and power-down parameters can be maintained for 30 minutes
42 pulse converter type and element 17, a diode three-phase full-bridge
18 Inverter type and element IGBT inverter bridge series
Electrical isolation section 19 whether to adopt the fiber optic cable fiber optic Agilent HFBR-EUS100
20 noise level ≤75dB
21 forced air cooling
22 overload capacity 120% 1min, 150% immediate protection (<10μs)
23 standard hard-wired control connection with the DCS
24 analog signal (input) specifications and quantity 4 ~ 20mA or 0 ~ 10V, 4-way
25 analog signal (output) specification and quantity 4 ~ 20mA or 0 ~ 10V, 2-way
26 switch signal (input) specifications and the number of dry contact relay, 6:00
27 switch signal (output) Specifications and counting dry contact relay, 5:00
28 Protection class IP20
29 standard keypad operation panel
30 Simplified Chinese language interface
31 inverter device Dimensions 3956 × 1200 × 2574mm
32 inverter device weight 5000Kg
Fourth, the energy saving effect analysis
1, the drive parameters
Model HARSVERT-A06 / 055 input voltage 6kV
Rated current 55A rated power 450kW
2, the motor parameters
Rated power 450kW rated voltage 6kV
Rated speed 985rpm Rated current 55A
3, energy efficient computing
Understood by the basic laws of fluid mechanics: fans, pumping equipment belong square torque load, the speed n and flow Q, pressure H and the shaft power P has the following relationship: Qαn, Hαn2, Pαn3; that is, , proportional to the cube flow and speed is proportional to the square of the pressure and speed, shaft power and speed.
According to the fan operating characteristics: The system uses the original tailgate when adjusted by the fan operating point A to point B moves along a curve; when the current system uses motor speed adjustment, fan speed is adjusted by the n0 n ', the fan operating point by point B drop to C point. Therefore, the use of high-voltage inverter, as shown in FIG its electricity savings.