Air compressor system selection of 12 steps, the wrong step with a large amount of electricity to pay the bill
Su Meiyan, Song Zhanming, Zeng Guomin
As a traditional power consumer of general machinery - compressor industry will face a major challenge. According to the relevant research report estimates, China's air compressor power consumption accounts for about 10-15% of the national industrial power consumption, annual power consumption of more than 500 billion kWh of electricity or more. Imagine, the country's compressed energy unit overall energy saving of 10% or more, how much electricity can be saved, how much carbon emissions reduction?
From the stand-alone selection, program design, networking control, IOT intelligence, etc. can be energy-saving at the application level, how to save energy at the application level, the following details.
1, stand-alone selection principles
1.1 Gas volume selection
Generally when selecting the gas volume, it is recommended to consider the fluctuation of gas consumption, daytime and nighttime gas distribution, the maximum gas volume and minimum gas volume, pipeline losses, capacity expansion and other factors. The overall gas volume has been determined, it is recommended to try to multi-table joint control, industrial frequency + frequency conversion and other programs. Frequency conversion machine is recommended to try to choose a constant pressure after the frequency fluctuation range between 60-100%, can take into account the efficiency and regulation.
At the time of selection, some dealers will have a misunderstanding: can choose a machine not to choose 2, the customer can afford to choose how big the range of machines. This will result in the use of a single machine in the absence of a spare machine occurs; machine selection will be too large frequent loading and unloading caused by water analysis leads to oil emulsification failure, which will seriously affect the life of the host.
1.2 Pressure selection
Pressure selection is recommended in accordance with the principle of high and low pressure, line separation. For example, 5bar go low pressure piping, 8bar go atmospheric piping. Separate pressure gas supply can avoid the waste caused by secondary "pressurization" and "depressurization" at the gas terminal. Nowadays, most users will choose a machine between 6-8 bar for general use, but "over-compression" and "under-compression" of the machine will consume extra energy, resulting in the unit is not energy-saving.
1.3 Selection of starting method
As a result of market speculation, now a swarm of recommended frequency screw machine practice is not entirely desirable, as in the car, only in a certain range of idling is the most energy-efficient working conditions, frequent starting and stopping and too long idling is also fuel consumption. Industrial frequency screw machine loading rate is high, inverter screw machine constant pressure frequency moderate can ensure that the compressor is in the best use of working conditions. As a selection principle, it is recommended to choose the frequency + frequency, multiple machines, the way of joint control.
1.4 Control mode selection
Compressor common control methods are: on/off, load/unload type, throttle control, variable speed control, multiple air compressor joint control. Users can choose the control mode can also be customized models. Good control mode selection can reasonably control the no-load loss and differential pressure loss, these losses occur in high unloading rate, higher than the use of pressure.
2、Station selection
2.1 Machine selection
Selection of energy-saving compressor with low specific power, according to the range of gas volume, fluctuations, intermittent use of gas and other circumstances to choose the appropriate type of compressor. Generally, it is not recommended to apply frequency conversion for all or too many compressors over 4 sets.
2.2 Post-treatment selection
At present, there are many kinds of post-processing equipments: cold dryer, heating regeneration dryer, heatless dryer, blower-heated dryer, etc. Comprehensively comparing the parameters of power consumption and gas consumption, energy-saving post-processing equipments are reasonably selected, and the post-processing equipments with frequency conversion control are preferred.
2.3 Piping selection
The right-angle elbow at the pipeline connection has a great destructive effect on energy efficiency, the right-angle elbow causes flow resistance to increase, the formation of additional work points; right-angle elbow to form a gas shock, local pressure increases, resulting in the compressor continues to run in a high gas pressure state, and easy to unload. Reasonable optimization of the pipeline barge point, can significantly reduce energy loss, this part of the loss can be almost eliminated.
Compressed air from a unified storage tank to send out, through the pipeline to the gas link delivery, efficient delivery form has a single point daisy chain, multi-point ring, but generally, the user because of the consideration of one-time investment savings and other reasons, the air pipeline direction is often unreasonable, resulting in excessive pressure loss, resulting in the need to supply a higher pressure of the gas. Piping should meet the user's requirements for flow, pressure, in the full life cycle of the comprehensive consideration of cost factors, try to reduce the pressure loss of the pipeline, while minimizing the application of elbows, valves, reducers. Generally from the whole machine to the terminal exhaust pressure loss as far as possible to control within 10% is good.
2.4 Selection of air storage tank
Usually screw air compressor has been equipped with aftercooler, air compressor exhaust for saturated compressed air. Conventional configuration is between the dryer and compressor with storage tanks and primary filter, then the compressed air in the tank after cooling condensate precipitation, so it is best to put the tank in a cool place and condensate effectively discharged. The capacity of the storage tank is determined in accordance with the compressor's output adjustment range and the varying demands of the air consumption.
In the application field, the problem that often occurs is that the capacity of the storage tank is insufficient. Due to the small capacity, the energy storage effect is poor, and the air pressure fluctuation is large, resulting in repeated loading and unloading of the compressor, which creates a large amount of energy waste. By increasing the storage tank, single unloading time over a certain length of time, then the unloading power consumption of the compressor will be reduced, to achieve energy saving effect.
2.5 Compressor waste heat utilization
Compressed air generation process is more complex, in the process of gas compression, the degree of heat, oil-free compressor can reach more than 100 degrees Celsius, the compressor consumes only about 20% of the power converted to compressed air power, the remaining 80% are converted to heat, so the compressor's waste heat utilization value is often higher.
The use of compressor operation in the process of hot oil, hot air for heat transfer, the heat will be transferred to the soft water medium, and then the heat of the soft water medium again, heat transfer to the hot water used by the user to achieve the utilization of waste heat. Using the heat energy in the compressor operation process to generate high-temperature hot water, and then use the high-temperature hot water as a heat source to drive the lithium bromide unit refrigeration, which is able to generate chilled water to supply the production process.
2. Intelligent Energy Saving
3.1 Monitoring items
Compressor exhaust volume, exhaust pressure, power; dryer output gas volume, dew point, pressure drop; cooling water system inlet/outlet water temperature and pressure, energy consumption of fan and pump; pressure, pressure drop, leakage of pipe network, etc.
3.2 Energy saving control points
Energy saving can be achieved through the flow control technology, frequency conversion speed control, single point/multipoint pressure regulation control, centralized control system, drying process improvement, heat recovery, pipeline network optimization, leakage monitoring, exhaust gas recovery and other ways to achieve the maximum degree of energy saving.
3.3 Energy-saving control
A huge database is established through data collection, and then a mathematical model is set up for analysis to find out the internal logical relationship and the connection between each other. The system can accurately calculate the energy efficiency level of the air pressure station through the collected data. According to the continuous data extraction and analysis in which time is the peak of gas consumption, what is the fluctuation range of gas consumption, pressure dew point fluctuation, etc., the use of big data calculations to give an early warning and provide a reasonable adjustment report, set the compressor within a certain range of the adjustment of the air volume, inlet and outlet of the water volume and other parameters, so that accurate energy saving can be achieved. If the predetermined adjustment range is exceeded, it will be pushed to the user for consent and then automatically adjusted.
Energy saving is a very deep "learning", the need for multi-disciplinary professional knowledge support, theory and logic is relatively easy to understand, but to do in practice and continue to explore the potential of the need for technical precipitation and application of data collection and transformation.