What are some ways to save energy in fan boxes? Check items by system, control, and equipment
Direct answer: To save energy in the fan box, you cannot replace the motor or change the frequency as soon as you start. The correct sequence is to first investigate the losses of the system itself, then adjust the operation strategy, and finally evaluate the power equipment plan. Air duct leakage, filter blockage, and excessive valve throttling will cause the fan to consume more power but fail to achieve the final effect. Addressing these system issues first is often more effective than directly replacing high-efficiency equipment.
Aili Industry is discussingWhen carrying out energy-saving modifications to the fan box , it is usually recommended to check them one by one at the three levels of 'system - control - equipment', and record data for each adjustment separately, so as to facilitate the determination of where the energy savings mainly come from.
Deal with system losses first
System losses are a common cause of high fan box energy consumption, but they are often ignored. The following three items should be checked first:
The air duct is leaking. Air leakage will cause the fan to supply more air, but not enough air volume at the end. Measure the air volume at the fan outlet and the main branch air volume. If there is a significant difference between the two, it indicates serious air leakage. Repair the air duct first, then evaluate whether the power equipment needs adjustment.
The filter section resistance is abnormal. After the filter accumulates dust, the resistance rises, and the fan operating point moves to the direction of small air volume. If the terminal air volume is insufficient, the operator may increase the speed to compensate, resulting in increased energy consumption. Record the pressure difference in the filter section regularly, and decide whether to replace the filter material according to the actual resistance change. System end configurationFor HEPA/ULPA high-efficiency filters , the initial resistance and resistance after use should be included in the calculation of the working point; when the process requirements are higher, it can be evaluatedDoes the ULPA ultra-high efficiency filter meet the requirements?
Valve is over-throttled. The system is designed based on the maximum load. In actual operation, the terminal demand is far lower than the design value. The operator can only adjust the air volume by turning down the valve. In this operating mode, the fan is still running at high speed, and the excess air volume is consumed by the valve. First review the minimum demand at the end, and then determine whether speed adjustment can replace throttling.
Adjust the operation strategy again
For systems with different needs during production and non-production periods, two modes of working air volume and duty air volume can be designed. It operates according to the designed working conditions during the working period, reduces the speed during the duty period, and uses on-site terminal measuring points to verify whether the low-speed mode meets the ventilation or pressure difference requirements.
The decrease in rotational speed will affect the air volume and available pressure. In order to reduce the current, the terminal ventilation or pressure difference cannot be controlled out of control. The control objective should be written as 'operate under the condition of meeting the terminal demand' rather than 'reduce the speed to the minimum'. For the pressure difference control system, the sensor position and pressure difference target should be confirmed during the debugging stage to avoid adjusting speed based only on one measuring point, resulting in insufficient air volume in the remote area.
From the fan law, the air volume is proportional to the rotational speed, and the shaft power is proportional to the cube of the rotational speed. The rotation speed is reduced by 20%, the air volume is reduced by approximately 20%, and the shaft power is reduced to approximately 51% of the rated value. This is the fundamental reason why speed regulation can save energy. However, the actual energy saving depends on the load curve, system resistance characteristics and speed regulation strategy. If the system operates at full load for a long time, the benefits brought by speed regulation will be limited; if there are obvious on-duty or partial load periods, the value of the speed regulation solution will be reflected.
The right sequence for a makeover
On-site measurements often reveal uneven adjustment of branch valves, filters that have not been maintained for a long time, or air duct leakage. The correct order of transformation is:
Measure the current air volume of each branch, the pressure difference in the filter section, the valve opening and the input power of the whole machine.
Address system damage that can be repaired, such as patching air leaks, replacing filters, and rebalancing branch circuits.
Recalculate the working point according to the corrected system curve.
Select a motor, fan or drive solution based on the new operating point.
If equipment is replaced and pipelines are significantly modified at the same time, it is recommended to record the data before and after each adjustment to facilitate the determination of where the energy savings mainly come from. Power figures for test conditions are missing and cannot be used for energy saving comparisons.
Finally compare power plans
Put the equipment before and after the transformation under the same air volume and external static pressure to compare the input power of the whole machine, and calculate the drive, construction and maintenance costs at the same time. The rated power of the motor is used to define the motor's capability, and the input power of the whole machine is the actual power consumption of the fan box under specific working conditions. The two are not the same number. When comparing, the supplier should be asked to indicate the rotation speed, filter status and valve opening during the test.
Both AC frequency conversion and DC speed regulation can reduce input power under partial load. You can't just rely on the word 'DC' to judge whether it will save more power than 'normal'. The actual energy saving depends on the load curve, system resistance characteristics and speed regulation strategy. If the system operates at full load for a long time, the energy saving space of the DC solution mainly comes from the improvement of motor efficiency; if there are obvious duty or partial load periods, the benefits brought by speed regulation will increase significantly.
Clean room ceiling air supply can be compared simultaneouslyFFU fan filter unit ; centralized management of multiple devices can be matchedThe FFU computer group control system realizes zone speed regulation and status monitoring. Protection of single process equipment can be consideredEquipment-side fan filter unit (EFU) . The final filtered air supply at the end of the air duct can beHigh-efficiency air supply outlet (HEPA BOX) . The division of labor between these equipment and the fan box should be clearly stated on the system flow chart.
Aili Industry can discuss the fan, motor, control and box structure.The actual effect of the fan box energy-saving modification configuration should be verified through debugging and operating data. Specific structure and configuration options can be found inIt is confirmed in the fan box product catalog that non-standard projects should provide equipment or machine room drawings, and then shape them based on the determined working points and on-site interfaces.
