Here's Some Advice to Ensure Long and Reliable Aeration Blower Performance

Long and cost-effective blower performance depends on proper installation, an understanding of control systems, and regularly scheduled maintenance.

Here's Some Advice to Ensure Long and Reliable Aeration Blower Performance

Indoor blower installations need to consider proper ventilation and effective heating or cooling to keep blowers operating within their temperature limits (Atlas Copco ZM multistage centrifugal blowers are pictured).

Blowers are integral to the wastewater treatment process, providing oxygen to help break down biological waste.

Smooth blower operation is essential to avoiding overaeration or loss of air supply. Blower manufacturers and treatment plant personnel can take steps to ensure that the equipment operates as intended. These include proper installation, machine control and maintenance.

Installation altitude

Blower installation is typically straightforward, but because blower designs vary, some issues can be missed. The most important is the machine’s temperature limitation. Although the manufacturer is responsible for clearly stating the equipment’s rating, that alone does not guarantee proper function.

Some machine ratings are set at sea level or only up to 3,000 feet elevation. When a blower is installed at higher elevation, it is critical to ask the manufacturer how this will affect the rating. Always consider that motors have less cooling air density at altitude.

Heat rejection

Another key item is knowing the heat rejection for equipment installed indoors. When equipment is run beyond its temperature limits, it may shut down and become inoperable, leading to huge aeration problems. In extreme cases, this may cause equipment failure and waste time and money.

It may seem that equipment rated for 110 degrees F is acceptable in an area with 100 degrees F maximum ambient temperature — but the blower room will always be hotter than it is outside. For example, a metal roof with no insulation generates significant extra heat.

To properly plan for ventilation, a complete analysis should be done to account for the outside temperature in addition to all heat sources in the blower room. With information on all potential heat sources, treatment plants can better analyze whether the equipment’s temperature limit will be exceeded at extreme conditions. If so, increased ventilation or ducting of cooling air and heat losses may be needed.

It isn’t always economical to plan for record temperatures, as these are rare, but it is good to know if the manufacturer has a way to run reduced loading to allow the equipment to operate. Running a blower at reduced load is better than not running it at all.

For colder climates, plants should closely monitor the minimum temperature and follow any requirements to keep lubrication and other items in line. Often, a blower room can be kept at an acceptable temperature just by using heat rejection from the equipment. Still, it remains necessary to check whether additional heating or ducting of process air is needed.

Blower control

Blower controls are easily overlooked but play a significant role in blower operation. Typically, the issue is lack of detail in documentation given to plant personnel. All blowers should have a controls narrative detailing how the controls work and how the plant interfaces with those controls.

Some blowers are supplied with no controls at all. Some come with proprietary micro-controllers and others with PLC-based controls. In each case, it is critical to understand how the equipment should be run. Most plants have a master control system that controls equipment automatically to maintain airflow or meet dissolved oxygen demand. Operators should thoroughly read, understand and follow the controls’ function for panel operation.

Running equipment in the automatic control mode is key to meeting the process requirements and saving energy. These systems can typically save 30 percent on energy versus a manual system. Operating equipment in manual due to misunderstanding of proper function can waste significant money.

Poorly working systems can put extra stress on equipment due to frequent shutdowns and restarts, leading to extra costs and overhauls down the road. To combat this, a plant needs good tuning from the equipment manufacturer and proper controls training for operators.

Effective maintenance

For long-term equipment operation, maintenance is a must. Blower manufacturers provide recommended maintenance schedules that include information about routine items so that plants can appropriately budget for these expenses. Money spent on scheduled maintenance saves money in the long run.  

For example, running a blower with a dirty filter allows dirt to be pulled into the equipment, and the dirt is then sent downstream, where it can cause clogged diffusers and other issues. In fact, the extra energy required to run a blower with a dirty filter would normally pay for the filter in less than one month due to the extra pressure loss at the blower inlet.

Aside from routine parts replacement, certain parts are only replaced when they stop working. Plant operators should ask for the expected lifetime of all major components and the replacement lead time in case of failure. Manufacturers should offer this information and be realistic about expectations. Plants that cannot afford to have a unit down for the time required to get spare parts should keep major parts in stock.

Regular maintenance and planning for overhauls is even more important in plants running near capacity. In these situations, any down equipment can quickly lead to violation of requirements and heavy costs to expedite parts and labor, or to rent equipment.

Most best practices for blower manufacturers and treatment plants boil down to one thing — effective communication. Because there is such variety in blower technology and plant applications, it is easy to overlook key aspects of installation and operation. Plants operators should describe their desired operation as clearly as possible, and manufacturers should give clear direction on how that can best be accomplished.

About the author

Travis McGarrah is product marketing manager for blower products for Atlas Copco. He can be reached at travis.mcgarrah@us.atlascopco.com or 281-840-0468.



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