Application of Sunwoele vector VFD (Variable-frequency Drive) in mixers

1. Configuration and operation overview of mixer

Mixing machinery is widely used in the production process of chemical, pharmaceutical, food, aquatic industry, plastics and other industries. When designing mixing machinery, a certain margin is considered according to the requirements of the working conditions. However, in the actual use of the mixer, It does not have to work at the maximum speed, and can work at a non-full load state for a lot of time; traditional mixers usually do not adjust or use mechanical speed adjustment; mechanical speed adjustment will increase the loss of the mixer, and at the same time make the mixer work In a fluctuating state, the mixer equipment also works in a "big horse-drawn cart" state, which is very uneconomical.

Due to the relationship between the power of the motor of pump equipment and its speed (frequency) when running in the variable frequency speed regulation mode, it can be seen that the energy saving effect of the VFD (Variable-frequency Drive) speed regulation method is very high, better than any previous speed regulation. method, and the investment can be recovered in a shorter time through energy saving. Since the load of the pump is similar to that of the liquid mixer, by installing a frequency conversion speed regulation and energy-saving device on the mixer equipment, many problems existing in the use of traditional mixers can be solved once and for all, and the investment can be recovered through frequency conversion energy saving.

2. Mixer frequency conversion solution

According to the configuration of the mixer and the characteristics of large operating torque, a set of vector-type VFD (Variable-frequency Drive) (selection is one step larger than the motor power) speed regulating device is usually installed on the mixer; the original power frequency of the mixer is preserved. system, and can be used interchangeably with the frequency conversion system of the mixer as a backup, and there is an interlock between the power frequency and the frequency conversion system. In the actual work process, multiple speeds can be set according to the characteristics of the mixing materials and the time for adding other chemical substances, up to eight different speeds. At the same time, the program running function of VFD (Variable-frequency Drive) can also be used. Up to seven automatic program running modes with different speeds and different times can be set, which greatly reduces the labor intensity of workers and improves production efficiency. Utilizing the powerful communication function of Sunwoele vector VFD (Variable-frequency Drive), combined with industrial computers and configuration software, network control with the main control room can also be realized to facilitate automated management of monitoring personnel. If the user wants to use DCS or FCS, then D/FCS can be responsible for collecting analog and switching signals, and all analog and switching signals output by VFD (Variable-frequency Drive) enter the DCS system to form a closed loop. control, and at the same time realize related auxiliary machine interlocking functions, etc. In order to ensure system reliability, it is recommended to add a power frequency soft-start bypass device to the frequency conversion system. The company has mass-produced industrial/variable frequency conversion integrated cabinet machines that meet the standards of various industrial occasions.

3. Characteristics of Sunwoele vector VFD (Variable-frequency Drive)

1. Suitable for high-end places such as large inertia and high-precision geopotential loads. The main circuit design adopts positive and negative busbar superposition and SCR non-contact optimization technology, which is more suitable for harsh environments such as humidity and dust.

2. Four options are available, V/F control and vector control modes with/without PG, both of which can obtain super starting torque and performance.

3. Open loop low speed and high rated torque output, speed control up to 100:1

4. Closed-loop zero speed can also be used for full torque control, with a control range of 1000:1

5. Advanced motor automatic tuning allows the motor to work at its best

6. Built-in automatic torque compensation function

7. Built-in slip compensation function operates efficiently

8. Built-in RS-485 communication interface, fully supports MODBUS communication protocol

9. Built-in PID regulator

10. Built-in parameter copy function

11. Energy-saving operation mode can be set, LED/LCD display interface is friendly

12. Multiple parameter online monitoring function and online adjustment function

4. VFD (Variable-frequency Drive) transformation control principle

Start/stop and speed adjustment can be performed on the console, and the frequency and current signals are connected back to the console in the control room for monitoring.

5. Advantages of transforming the mixer into a variable frequency speed regulating device

1. The frequency conversion energy-saving device of the mixer is open-loop adjustment;

2. Soft start\soft stop mode can reduce the starting inrush current;

3.VFD (Variable-frequency Drive) has intelligent protection and can automatically shut down in case of failure;

4. Different speeds can be used according to different processes;

5. Energy saving through frequency conversion speed regulation: Since the power and speed characteristics of the mixer's motor when operating in the frequency conversion speed regulation mode are similar to those of pump loads, that is, its operating power is proportional to the cube of its speed (frequency), and the viscosity is high. The ratio will decrease (generally between quadratic and cubic). Therefore, when using VFD (Variable-frequency Drive) method to adjust speed, a considerable power saving rate can be achieved.

Example: A mixer capacity: 1×93KW, speed 180r/min, actually 160r/min can also be used; therefore, frequency conversion power saving rate = 1-1603/1803=0.3=30 or =1-1602/1802=0.21=21 , between 21~30.

6. Performance after system modification

(1) Using VFD (Variable-frequency Drive) control, maximum energy saving can be achieved under the conditions of meeting the usage requirements.

(2) Due to reduced speed operation and soft start, vibration, noise and wear are reduced, the maintenance cycle and service life of the equipment are extended, the MTBF (mean time to failure) value of the equipment is improved, and the impact on the power grid is reduced, improving system reliability.

(3) The system has various protection measures, which greatly improves the operation rate and safety and reliability of the system.

(4) The frequency conversion speed control system and the power frequency control system can be set to be interlocked with each other, which will not affect the operation of the original system. Moreover, when the frequency conversion speed control closed-loop control system is inspected, maintained or malfunctions, the original power frequency control system can still operate normally. run.