Absrtact: The functional requirements and energy-saving requirements of the purification project are constantly improving, so the air and water systems of the purification and air-conditioning project are improved by technical energy-saving measures. In this paper, through fan control, the way of drainage and water replenishment of the circulating water system is modified to achieve the energy-saving effect of air-conditioning operation.
Key words: air conditioning system; frequency converter; circulating water; energy saving
Introduction
Air conditioning system is playing a more and more important role in the purification industry, and it is basically in the leading position. Biological purification projects in recent years,
Especially, the requirement of air conditioning system in animal laboratory is getting higher and higher. The main function of purifying air-conditioning system is constant temperature and humidity. Therefore, the design and construction of purifying air-conditioning system must meet the new requirements of the continuous development and improvement of purifying industry. In order to reduce energy consumption and environment in enterprises, at the same time, correct use of resources has a great effect. In the process of air conditioning operation, the main energy consumption in the air conditioning system is the power of fan operation and the chilled water in the circulating water system.
1. Talking about Energy Saving from Electrical Control System
Clean air conditioning system is characterized by large air volume, resulting in its high energy consumption, and reasonable design and management can ensure a good indoor environment, but also significantly reduce operating costs. Previously, air volume and pressure were regulated by the air valve in the ventilation duct, but it is a great waste of air volume. From the point of view of energy saving, it is very uneconomical. At present, the frequency conversion control system is used more to save energy. Fan is a variable load equipment. The speed of fan directly affects the load. After reducing the wind volume and pressure of fan, energy saving can be achieved. This kind of load can save 20% to 30% of the power after increasing the speed control system. The energy-saving effect is very considerable, and the general speed control performance can meet the requirements of the fan on the speed range and dynamic performance.
Selection of 1.1 Inverter
Generally speaking, energy saving of production equipment is achieved by reducing input power or running time. According to the torque and power characteristics of the fan, when the required air volume decreases, the speed of the fan can be reduced, and the corresponding input power will also be reduced. Therefore, the power can be greatly saved. At the same time, on the premise of meeting the production needs, intermittent operation can shorten the running time and save electricity. Fan is a kind of reduced torque load, load torque is proportional to the square of rotational speed, with the reduction of rotational speed, the torque will also be reduced; secondly, fan load does not need to start and stop frequently, basically not instantaneous overload. Ordinary function frequency converter can be selected to meet the actual needs technically.
When choosing frequency converter, we should pay attention to the data of frequency converter, the capacity of frequency converter, power supply voltage, current, output frequency and so on. These are the important basis for choosing frequency converter.
1.2 PLC+Inverter Control System
Electrical control system is the key part of the whole system. The closed-loop control mode is adopted to control the speed of the fan. The wind speed and pressure sensors are assembled at the outlet of the air supply post, which can reflect the operation of the system according to the output signals of the sensors. When the wind speed and pressure do not meet the requirements, PLC controls the frequency converter to adjust the speed of the fan according to the feedback digital signal, and increases or decreases the speed of the fan to meet the ventilation requirements of the production process, thus achieving the purpose of energy saving.
1.3 Man-Machine Communication System
In order to facilitate the control and monitoring of the air conditioning system, touch screen in the control room is connected to the PLC to form a man-machine communication system. Man-machine interface can adjust and control the operation status and process parameters of the whole ventilation system manually, and can also monitor the output frequency of the frequency converter, wind speed and other data in real time. Change. When there are special requirements in the production process, it can adjust or switch to manual control mode in time.
1.4 Night Low Frequency Operation
Some enterprises require 24-hour uninterrupted operation of air-conditioning systems to ensure that the clean area maintains positive pressure on the general area. So it can't stop running during the night when nobody is there, but maintaining the wind speed and pressure in normal production will result in waste of energy. This requires that the frequency should be lowered during the non-production period, and at the same time the requirement of wind pressure should be met.
The low-frequency operation at night can be realized by the multi-band operation function of the frequency converter. The idle time period at night can be set by time relay to control its automatic switching to low-frequency operation at night. When there are special requirements, it can also manually change the frequency, or turn off the time cycle control, switch to manual control.
1.5 Revamping Effect
Through the improvement of air conditioning fan control system, not only the ventilation requirements of the process are met, but also the unnecessary energy waste is saved. At the same time, the operation and supervision of the operators are facilitated, the labor intensity is reduced, and the production cost is greatly saved. In the normal production process, a 30 kW fan has a full speed power of 27 kW after eliminating no-load losses, and the average air volume is about 80% of the full speed. After adjusting speed by frequency conversion, only 16.8 kW is needed, which saves 10.2 kW of power and saves more than 70,000 yuan of electricity per year.
2 Talking about Energy Saving from Cooling Water System
In air conditioning systems, there are usually two-stage surface coolers, which need circulating chilled water to dehumidify and cool down. Twin-screw compressor is commonly used in chiller mainframe, which can provide 5 ~15 ~C chilled water. The water quality of circulating water will change after a certain period of operation. In order to protect refrigerators, surface coolers and circulating water pipes, it is necessary to replace the water in the pipes regularly. When the turbidity of water is more than 15 mg/l, calcium ion is more than 220 PPm, magnesium ion is more than 60 PPm or chloride ion is more than 150 PPm, it can not be used again.
2.1 Current Situation of Recycling Water Supplementary System
Drinking water has been used in the previous water supply, resulting in a large amount of company drinking water; while most of the washing wastewater in production is directly discharged into sewage pipelines, and the full utilization of water resources is not realized.
The cycle of circulating water replenishment for chillers is about one week, and the cycle is very short. The total amount of drinking water replenishment is about 1500 tons per year. The company uses purified water and injection water every day for washing posts. The total amount of washing wastewater produced each month is about 600 tons, which fully meets the water consumption of circulating water supplement, and the water quality fully meets the water supplement requirements of circulating water system. The ion content is even much lower than that of drinking water previously used.
2.2 Pipeline Reform of Drainage and Circulating Water Supplementary System
During the operation of the circulating water system, the washing wastewater with low ion content was used instead of drinking water as the supplementary water source. Then through the pipeline transformation, the washing wastewater drainage pipe is connected with the water inlet of the recovery pond to realize the recovery of the washing wastewater. The outlet of the recycling tank is connected with the supplementary water of the circulating water through the pipeline, so that the recovered water after precipitation in the recycling tank can enter the freezing circulating water system.
2.3 Improvement of Water Supply Operation
The original recharge of circulating water uses the way of side-by-side recharge and side-by-side drainage, which causes the recharge of new recharge into the circulating water system to be discharged directly with the discharge of circulating water and increases the amount of recharge water. The water supply mode of first drainage and then replenishment is applied to the operation of water replenishment. Combining with the original replenishment and drainage mode, the water replenishment can be saved and the waste of water resources can be greatly reduced.
2.4 Revamping Effect
The recharge period of circulating water is one week before revamping, and after revamping, the average recharge period is two weeks. Recycling water supply sources are all recycled water, which can save nearly 1,000 tons of drinking water each year and create more than 5,000 yuan of economic benefits each year.
3 Concluding remarks
Summarize, through the fan frequency conversion speed regulation and the improvement of refrigeration circulating water supplement system, save electricity and drinking water usage, and put forward a new idea of recycling washing wastewater as refrigeration circulating water supplement source, achieve the purpose of energy saving and emission reduction.
Reference
[1] Han Anrong. General Inverter and Its Application [M]. Beijing: Machinery Industry Press, 2003.
[2] Peng Hongcai. Principle and Drive of Electric Machinery [M]. Beijing: Machinery Industry Press, 2005.
[3] Chen Boshi. Automatic Control System of Electric Drive [M]. Beijing: Machinery Industry Press, 2009.
[4] Luo Xuelian. Design of PLC control system for AC variable frequency speed elevator [J]. Electrical Age, 2003, 11:68-70.
[5] Zheng Xiaojuan. Energy-saving analysis of chillers equipped with multiple screw compressors [J]. Refrigeration, 2001, 1:52-54.
As a technical enterprise in Shandong Province, which focuses on the design, research and development, construction and installation of hospital operating room purification, dust-free workshop purification, laboratory purification and other engineering projects, Edward purification has always been firmly on the road of professional purification engineering construction and development, and is a truly trustworthy professional purification industry for domestic enterprises. To learn more about the medical purification industry, please pay attention to the Wechat Public Number: Aide-188 (Aide Purification and Oxygen Supply)
