light industry

一、preface
Our Yi Chuang Fei record company for many years to come, the promotion of industrial energy-saving technology, and accumulated a wealth of experience in the field of industrial energy efficiency. In view of the current domestic numerous commodity concrete production enterprises of high energy consumption, our R & D a vector frequency converter of Guangdong Province, a concrete Co., Ltd. successfully were for concrete mixing production line of energy saving and achieved good economic and social benefits. In order to make the majority of commodity concrete production enterprises can enjoy the achievements of the application in a timely manner, we are here for the application case announced, hope can the concrete mixing industry energy saving work to very good role in promoting.

 

 二、Background of project transformation
Guangdong Province, a concrete Co., Ltd. the original two concrete mixing line, the major energy consuming equipment in each production line for double a 30kW inclined belt and a 2 x 37KW mixer, three motors with Y - delta starter system in no material light load (wait state), total current 80A in full load (mixing), the total current 100 ~ 130a, system work duty than the average about 50%, average operating current of the single system about is about 100A, equivalent to the consumption power of about 50 kW. The average power consumption of the two units is 100kW. Annual electricity consumption is about 100kW x 20 hours x 300 days x 0.7 yuan = 420 thousand yuan.

 

 三、Project reconstruction scheme
1, transformation method
In order to adapt to the market, improve the competitiveness of products, energy saving is one of the most effective ways to reduce production costs. In view of the actual situation of the concrete mixing line of the company, we have reached a consensus on the energy saving transformation of concrete mixing line. Through the two sides of the collaboration to solve the problems encountered in the process of transformation, finally completed the transformation, achieved good economic benefits.
The transformation method is using advanced can be programmable control (PLC) technology and transducer technology, to program control to replace the relay, contactor control, realize inclined belt conveyor and dual mixer according to the coordinated operation of the process, to achieve safety, energy saving, lower maintenance cost and convenient operation.
2, the main technical indicators of the system
(1): mixer motor three-phase AC asynchronous motor, 4 pole, 37kW, number 2, shaft synchronous operation
(2) inclined belt conveyor: three phase AC induction motor, 30kW, 4 pole, number 1
(3) system load rate: 50%
(4) motor control and operation mode: the Y-delta starter, continuous operation mode
(5) no load current: 80A
(6) full load current: 120A
3, the system main control scheme
(1) retains the original Y delta starter, as a standby system;
(2) due to space constraints, wall mounted inverter;
(3) the Y-delta inverter working mode and working methods using automatic switching form;
(4) using the programmable logic controller to control and coordinate the work of the two inverters according to the batching process flow;
(5) with detailed control function and working status, fault signal display, to facilitate the operator to monitor, control and maintenance personnel;
(6) perfect protection function.
4, system control points
(1) speed regulation method
ECF500 variable frequency speed regulation system with vector control function.
(2) the control actions of the system include: start, stop, low speed operation, high-speed operation, emergency stop, etc. all of these can be controlled by programmable logic controller (PLC).
5, the control system needs to pay attention to the problem is:
(1) the motion of the inverter is controlled by PLC, and the control condition of PLC is determined by the production process;
(2) the acceleration, deceleration time and the parameters of the converter are set according to the actual conditions of the load.

 

四、 Main results of system transformation
1, energy saving effect is remarkable
Before and after the transformation, the system comprehensive energy saving more than 30%.  

system state	System motor total power	motor speed	Average current before transformation	Average current after transformation	Power saving rate
No material	104kW	25Hz	80A	20A	约70%
Material	104kW	50Hz	110A	65A	约40%

 

2, improve the stability of the system, reduce the system failure rate, reduce the system maintenance costs. Mainly reflected in the following aspects:

(1) to extend the service life
Due to using the transducer to control the motor running motor to achieve the soft start, so as to avoid the previous motor Y - Delta start of electrical equipment and machinery and equipment impact, prolongs the service life of the equipment.
(2) strong protection function
As the inverter's electrical protection function is very perfect, so that the system has a short circuit, overload, over current, lack of phase, under voltage protection function, to maximize the protection of the safety of the motor.
(3) the failure rate of the control system is greatly decreased
The original system is due to the very complex contactor, relay system control, higher failure rate. By adopting the variable frequency control system, the control system can be greatly simplified, and the reliability is greatly improved.
(4) improve the synchronization performance of mixer.
Due to the adoption of the inverter Yituo two drive mode, making the synchronous nature of the mixer double reamer is very good, greatly reducing the internal friction of the dual mixer, saving a lot of electricity.
(5) increase the power factor
In situ power factor compensation is realized by frequency converter, the power factor is above 0.95, which can not only save the electric energy but also improve the efficiency of the power factor.

五、Concluding remarks
The energy saving renovation projects retained the original control system and distribution system, at the same time, in the total system power line installation of watt hour meter, by switching frequency and frequency, can be directly reflected the transformation of the energy-saving effect, provide visit the strong basis for the future promotion of the industry.