As a high-energy-consuming equipment in sewage treatment, the choice of blower is related to the operating cost of the entire sewage plant. There are many ways to deal with it, and the most widely used method is the activated sludge method, which is commonly referred to as aeration, which uses a blower as the main equipment.
According to statistics, the energy consumption of blowers accounts for 50%-60% of the total energy consumption of sewage treatment, so for sewage treatment plants, the choice of blowers is one of the main factors affecting operating costs.
The role of a blower in sewage treatment
Oxygen supply and aeration: The conversion rate of oxygen can be improved by using a blower, and it can also aerate the air volume. The smaller the diameter of the bubbles, the larger the overall surface area and the better the effect.
Stirring water body: The sewage treatment pool is divided into several compartments with separate water inlets by partition walls, and each compartment is divided into several corridors. After the sewage enters the pool, it flows in the corridors in sequence and is discharged to the other end. The blower can transport the air through the pipeline to the air diffusion device at the bottom of the pool, and become air bubbles to diffuse and escape. After the air bubbles enter the sewage, they will contact the sewage, and the oxygen will dissolve into the water, making the biofloc in a suspended state.
Backwashing: In water treatment, after the filter has been working for a period of time, it is necessary to use reverse water flow (from bottom to top) to flush the filter layer, to wash down the suspended impurities on the surface of the filter material by high-speed water flow, and to take out the filter layer through the water flow. layer, so that the filter layer is regenerated, and the filter tank resumes normal operation to ensure the filtration rate and water production.
Why choose an oil-free screw blower?
1. The screw blower is more energy-saving
Due to the high energy consumption of Roots fans, the comprehensive cost per unit flow is higher than that of multi-stage centrifugal and single-stage high-speed centrifugal fans. When the flow rate is above 100m3/min, single-stage high-speed centrifugal fans have higher operating efficiency, and magnetic (air ) Suspension fan has a certain operating efficiency and low noise, but the cost is the highest and the maintenance is complicated. It is currently applied to site with high environmental standards. In the actual selection, factors such as the demand for flow regulation, installation conditions, and the convenience of operation and maintenance should also be considered.
Magnetic levitation centrifugal blowers and air suspension centrifugal blowers are speed-type machines, and their efficiency curves relative to pressure and flow fluctuate greatly. There is a high working efficiency at a specific working point, but after deviating from this specific working point, the working efficiency will decrease.
2. The working conditions of the screw blower are more adaptable
In various applications in the industrial field, the range of actual working conditions of users varies greatly. In this case, the actual average efficiency of the twin-screw oil-free blower is higher than that of the magnetic levitation centrifugal blower and air suspension centrifugal blower. The average efficiency is higher. When the user’s working conditions vary widely, the difference in efficiency between the two will increase significantly.
Affected by working conditions, the typical feature of sewage treatment conditions is that there is a large amount of dust in the air. For the twin-screw oil-free blower, fine dust can pass through the gap of the compression chamber without adverse effects.
For magnetic levitation centrifugal blowers and air suspension centrifugal blowers, the increase in air intake resistance, decrease in air intake pressure, and decrease in air intake volume will cause some problems: first, the fan deviates from the optimal operating point, and the operating efficiency will be reduced; It is easy to leave the stable zone of high-speed operation, and phenomena such as jitter and surge occur.
3. The screw blower runs more stably
The working conditions of the industrial environment are often more complicated, and the air duct resistance, flow rate, and pressure change range are large, and the stability of the fan – the anti-variation ability and the adaptability of the working conditions are very high.
Blower application selection
The air volume of the blower can be calculated from the chemical oxygen consumption, and the exhaust pressure is determined by the water depth (the distance from the aeration port to the water surface). When designing the system, the pressure loss of the pipes, valves, elbows and aeration heads should also be considered. Add 9.8kPa on the basis of the water depth. At the same time, the depreciation loss of the gas supply system due to the running time factor should also be considered, and the gas volume space should be appropriately increased.