Pu Chuan science and technology frequency conversion technology in fan and water pump load energy-saving application

1 Introduction

Boiler heating is related to the daily work and life of millions of households. Especially in large-scale centralized heating systems, there are constant pressure, temperature control and high reliability requirements. For heating boilers, the main energy consumption is the consumption of coal and the consumption of electrical energy. Therefore, how to increase the efficiency of coal combustion and the use of electrical energy has become an important way and means for enterprises to save energy and reduce consumption.

In the boiler heating system, there are mainly air conditioning fans, circulating pumps, and coal feeders. Among them, the wind turbine mainly regulates the size of the air intake, the air volume is adjusted too much, and the oxygen content in the air is excessive, then the heat energy is wasted, the air volume is adjusted too little, the carbon residue remains too much toner, and coal is wasted. Therefore, in order to improve the control level and ensure that the oxygen content of the air and the residue of carbon residue reach the standard, the amount of air must be adjusted effectively. The adjustment method must be convenient, sensitive and reliable. In the past, adjusting the air volume was achieved by adjusting the opening of the air damper. This method, whether it is manual adjustment or mechanical automatic instrument adjustment, has a considerable part of the electrical energy conversion mechanical energy consumed in the throttle resistance, and can not achieve the purpose of energy saving.

Blower protection in the boiler system is a key issue for the entire boiler combustion system. The traditional use of baffle and valve control. The use of electricity is inefficient, and it is necessary for professionals to operate to ensure the highest overall efficiency.

When the flow control of the fan, coal feeding, and the residue removal system are evaluated as a whole, the power consumption efficiency and combustion efficiency are the most important issues. Therefore, in the boiler drum, induced draft fan and circulation pump and other equipment, promote frequency conversion speed energy-saving technology to replace the backward windshield, so that the fan is always in a scientific and economical operation, improve the company's comprehensive economic and social effects, it is very important The significance. After the implementation of the above-mentioned contents of the industrial boiler energy-saving renovation, the consumption of coal or other fossil fuels will be greatly reduced. Therefore, reducing the greenhouse gas CO2 emissions will help to alleviate global warming, while also reducing the acid rain gas SO2 and Emissions of total suspended particulates are beneficial to improving the ecological environment in the region.

PI7800 high-performance frequency converter developed by Pu Chuan Technology (a new key product of the National Torch Program) uses TI's motor-specific control chips and high-power IGBTs to achieve high-performance voltage space vector control; based on "10 key motor energy-saving projects," the development of PS7800 series motors Environmental protection and energy conservation devices have achieved good results in petrochemical, building materials, and heating applications, with significant social and economic benefits.

2 Dalian Pu transmission frequency conversion technology main application

2.1 Principle of Energy Saving Reform

According to the basic laws of fluid mechanics, fans and pumps are all square torque loads. The rotational speed n and flow Q, pressure H, and shaft power P have the following relationship:

Q∝n, H∝n2, P∝n3;

That is, the flow is proportional to the speed, the pressure is proportional to the square of the speed, and the shaft power is proportional to the cube of the speed.右 The figure on the right shows the energy-saving effect of fan equipment using frequency converter or motor environmental protection and energy conservation.

When the on-site demand for fan flow is reduced from 100% to 50%, the use of speed adjustment will be more than 75% of the energy savings ratio than the original valve. î ‹

In actual operation, the energy saving effect is obtained according to the calculation formula of the compulsory national standard of GB12497 "Three-phase Asynchronous Motor Economic Operation".

2.2 Application Equipment

1) Boiler: blower fan, induced draft fan, grate motor;

2) Heat exchanging station: An important part of the central heating system. The heat exchanger is the steam (110°C to 130°C) or high-temperature hot water (85°C or more) in the heat pipe network system via the heat exchanger group and the terminal pipe. The circulating water in the net exchanges heat, and then is pressurized by the pipeline pump to send the recycled water to the radiators or fan coils used by various users. The circulating water then returns to the heat exchange station for reheat cycle, and the cycle is repeated. . When designing a heat exchanger group, since the heat exchanger is a fixed range of output heat, the design is selected according to the user's maximum load. In actual use, due to many factors, such as architectural planning, construction period, low occupancy rate in residential quarters, seasonal environment changes, etc., the actual required load changes are greater. Generally in the heat transfer station pumps: a network of circulating pump motor, secondary network circulating pump motor, make up the water pump, etc. use the frequency conversion device.

3 Dalian Pu transmission inverter application example

Wafangdian *** Heating Co., Ltd. has a total of more than 30 coal-fired boilers. Since 2001, the company has used frequency conversion inverters to convert the existing boilers to frequency conversion. Through transformation, not only saving electricity, saving coal It has achieved certain economic benefits in terms of other aspects, and it has also greatly improved environmental protection. It has been evaluated by the energy conservation service center of Dalian City. In 2006, the company continued to carry out frequency conversion in the original old boiler, and two new 30-ton boilers adopted the universal transmission frequency conversion control scheme from the beginning of installation. Now we will analyze the operation of these two boilers during a heating period.

30 ton boiler configuration: blower fan (55kW two), induced draft fan (132kW two), grate motor (4kW two), boiler make-up pump motor (4kW two), primary net circulating pump motor (110kW Two) and secondary net circulating pump motors (two 132kW and two 75kW) adopt the universal frequency converter for frequency conversion control. The comparison results of the running time, operating frequency of each motor and the traditional air conditioning door adjustment methods in terms of electricity saving and coal saving are shown in the table below.

The total power for frequency conversion application of this boiler is 512kW*2=1024 kW.

The total energy saving on the day is:

(55*38%*10+132*42%*10+4*51%*10+4*22%*10+110*22%*24+132*20%*24+75*15%*24) *75%=1,707 kWh,

A heating period is 147 days, and the total energy saving is: 1707*147=251,039 kWh.

Calculated by 0.5 yuan/kWh, a heating period will save 125,520 yuan.

In addition, 6% of coal is saved, which is calculated on the basis of 100t coal consumption per 30t boiler.

A heating period 100*6%*147*300=264,600 yuan.

The total investment of this boiler converter project is 250,000 yuan.

Payback period: basically one heating period can recover the investment.

All fans and water pumps use one-to-one configuration (ie, a universal transmission with a motor). The original power frequency system is reserved and used in stand-by with the variable frequency system. In general, open-loop control is used.

4 Dalian Pu transmission inverter investment and energy saving

The average energy-saving effect of universal transmission energy-saving systems (devices) in fan and water pump equipment can also be achieved by 20-50%. Average values ​​can be averaged without being influenced by other factors. The average value of these energy-saving effects is Obtained from practical application, the investment recovery period of frequency conversion energy saving system is generally 6-15 months.

A 40-ton heating boiler of the Harbin Boiler Heating Company provides heating for the Zhengyang River District, with a heating area of ​​approximately 500,000 square meters, due to a large temperature difference (from October 25 of the previous year to April 15 of the following year) in one heating period ( Between zero and minus 30 degrees, this requires that the heating boiler heat supply must adjust the variable with the change of temperature. In the past, the damper was used to adjust the drum and the amount of induced air, but due to mechanical (rust failure) and artificial reasons ( Distance, inconvenient adjustment, etc., often cannot timely adjust the flow and cause waste of electricity and coal. After adopting the transmission technology of Universal Transmission Technology to adjust the damper plate to the frequency conversion speed regulation mode, the operator can adjust the input current frequency of the fan motor timely, accurately, easily, and conveniently according to the temperature change, thereby scientifically adjusting the drum and induce the wind In comparison, the average energy-saving rate is as high as 60%, saving about 10% of coal, and it also reduces the flue gas exhaust concentration, with considerable economic and social benefits.

Two 20-ton boilers in a machinery plant are used for steam hammer steaming in the forging plant. Two sets of 20-ton boiler steam supply are designed according to the average 90% start of the steam hammer in the factory. However, in actual operation, the 90% operating rate is often not reached, and one boiler is not enough for steam supply. When two boilers supply steam, Steam pressure rises and it has to be drained, causing great waste. After the use of universal transmission frequency control technology to adjust the drum, induced draft fan, grate, coal feeder, motor speed, the problem has been completely resolved, so that according to the factory steam hammer start amount, timely and timely adjustment of boiler steam production, both satisfied Production needs, but also saving electricity, saving coal, according to statistics, only 4 months to recover all the investment.

Two 35-ton boilers of a chemical plant, using two 3000KV self-provided power generation units with differential pressure to use steam as a heat source for vacuum salt production, adopting universal transmission frequency conversion speed-regulation energy-saving technology to adjust the drum and air volume, and adjust the accuracy Improve, drum, induced wind volume ratio is more reasonable, to overcome the past when the air volume is too large, the exhaust temperature increases, wasted heat, air volume adjustment is too small, the residue of carbon residue exceeded, and wasted coal resources. Energy-saving rate reached 37%, saving about 10%. The comprehensive economic benefits are remarkable and generally welcomed by the employees.

5 Dalian Pu transmission inverter energy efficiency is significant.

1) Significant power saving effect: General energy saving up to 30%

2) Improve the working environment: Due to the use of universal transmission frequency control, according to the changes in the amount of gas can be adjusted at any time the induced draft fan, blower air volume, on-site testing, noise reduction, praised by the operator

3) Reduced maintenance: As a result of adopting the universal transmission frequency conversion soft-start technology, the mechanical impact and the impact on the power grid are reduced, the maintenance volume is obviously reduced, the downtime is reduced, and the maintenance cost is reduced by about 50% compared with that before the retrofitting.

4) Automatic control system of heat exchange station: Circulating pump and make-up pump operate according to requirements, which realizes the unattended operation of the heat exchange station and improves the degree of automation of the system. When the circulating water pump is reformed, a pressure sensor is used to detect the pressure of the pipe network. Through the PID adjustment, the analog signal is given to control the frequency converter, and the frequency converter gives a certain voltage and frequency feed pump to adjust the pump speed and output power to form a closed-loop feedback system to maintain the pressure stability of the pipe network and achieve the outlet temperature. Automatically control the constant pressure control.

5) To achieve reduction of pollutant emissions such as CO2 and SO2 with good environmental effects.