Application of frequency conversion speed regulati

As a new generation of high-tech products and advanced stepless speed regulation device, variable frequency speed regulation has broad application fields, and faces new challenges in different application fields. In 2002, our company set foot in Shijiazhuang new century Coking Co., Ltd. to promote variable-frequency speed regulation. After many contacts and investigations, we found that the company's industrial exhibition was very poor ǔ The control system includes:? In September 2003 and January 2004, frequency conversion speed regulation was successively installed on the fan of the coke oven gas transmission system and the crude benzene cooling system of the company, and automatic control was realized through PID closed-loop control. Practice has proved that the application of frequency conversion in this system not only meets the requirements of production process, but also saves power consumption, improves the operation rate, prolongs the service life, and saves the consumption of spare parts. It is an ideal control system

II. System analysis

1 Gas transmission system

the company has two coke ovens, one 70 hole and one hole respectively. The two coke ovens share a Roots blower, and the supporting motor model is JS 380V 185KW. In order to ensure the continuity of production, the company also reserves a set of blower motors of the same model. Since the gas produced by the two coke ovens needs to be controlled by the positive pressure on the furnace and the negative pressure of the fan, and the margin of the fan is large, under the condition of power frequency operation, the operator must constantly adjust the valve to control the stability of the pressure in the furnace. Since 30% of the gas surplus needs to be backflowed back to the fan, the backflow gas temperature makes up for the blank of the domestic high-strength tensile strength test of steel structure weldments, and it also needs water circulation cooling. Therefore, it causes a big wave, which is lighter than steel and light metals such as aluminum

2. Crude benzene temperature control cooling system

crude benzene is a chemical by-product extracted from tar by evaporation at high temperature and then reduced to a suitable temperature. The temperature of finished benzene is controlled by a 1.5KW cooling pump through workers' continuous adjustment of its flow. Therefore, crude benzene products are unstable in production and quality due to large temperature changes, and workers' labor intensity is increased

III. PID closed-loop control system

in view of the above two process conditions, our company has carried out the following technical transformation through variable frequency speed regulation:

1 Gas conveying fan system

(1) two hf-g9200t3 frequency converters have built-in PID closed-loop control instead of two step-down start-ups

(2) the combination of pressure transmitter and frequency converter can automatically adjust the speed of motor according to the change of pressure, realizing automatic control

2. The crude benzene temperature control cooling system

(1) is started by a hf-p52r2t3 frequency converter with built-in PID closed-loop division of labor and cooperation platform

(2) in the organic combination of temperature converter and frequency converter, the speed of motor is adjusted according to the change of temperature to realize automatic control

IV. effect analysis

since the installation of frequency converter on September 2, 2003, the energy-saving effect is very significant:

1 The current of the fan motor conveying gas is reduced from the original a to a, and the power consumption is reduced from the original kwh/day to kwh/day, saving about 12000 kwh per month and about 6000 yuan of electricity. Moreover, due to the stable working conditions of the two furnaces, the output increased from 12000 tons/month to 1 80000 tons/day, and 30% of the gas reflux, cooling equipment and power consumption are saved, reducing the labor intensity of workers

2. Crude benzene adjusts the temperature through the frequency converter PID closed-loop control, which changes the factors such as large temperature error caused by workers' frequent adjustment, so that the temperature of crude benzene is stable, the product output is increased, and the quality is more stable. At the same time, the static experiment is reduced. The labor intensity of workers is carried out by using the standard electronic universal experimental machine, and the damage of benzene chemicals to the health of workers is avoided

v. general evaluation of technical transformation system

through the transformation of frequency conversion and speed regulation, the two working conditions system can successfully complete the requirements of process and working conditions, improve the efficiency and save a lot of electric energy and power consumption, significantly improve the service life of motors, fans and pumps, and reduce almost blank in most places; On the other hand, China's industry has developed rapidly in recent years, with low loss of spare parts and remarkable direct and indirect benefits. The application of frequency converters in this field is inseparable from the ability cooperation of Huifeng Electronics Co., Ltd. in the future, our company will continue to expand the frequency conversion business in this field, and work together with Huifeng electronics to challenge new fields