Cover air demand with greater efficiency and flexibility!

Replacement of old air compressor equipment at a municipal wastewater treatment plant with a focus on energy savings and the ability to adapt to short-term large fluctuations in compressed air demand. 
Single-source compressed air production for increased availability is the answer.

Replacement of ageing air compressor equipment at a municipal wastewater treatment plant with a 41,000 population equivalent.  

The aim for investment in new equipment not only focussed on achieving significant energy savings, but also on the ability to accommodate short-term large fluctuations in compressed air demand and to create a wide control range that enables all compressed air demand to be covered as efficiently as possible.
The compressed air is generated centrally and is distributed to the zones for aeration via a collection pipe equipped with gate control valves.

The first stage for KAESER's project engineers was to determine the necessary operating parameters. This included identification of the flow rate and operating pressure trend over time. Once the results were in, it was clear that maximum controllability and energy savings would be achieved by splitting the load across multiple machines graduating in power and control mode.

This in turn resulted in a control range of 280 to 3150 m³/h with a pressure differential of 560 mbar, which translates to control ratio of more than 1:11. Two DB 236C-OFC type rotary lobe blowers (with frequency converter) and two DB 236C-STC (with Y/D starter) machines were installed. A SIGMA AIR MANAGER (SAM) master compressor controller co-ordinates the individual machines to operate in unison according to actual compressed air demand with maximum efficiency. The SAM master controller is equipped with specialised software that is specifically designed to manage operation of low pressure compressors.
The controller implements sliding pressure control via connection to the process control system.

Regarding the modernisation process, the plant manager believes it has been very helpful in retrospect to have had every aspect of compressed air production taken care of by a single source. 

As he confirms, this approach not only reduces the number of communications and physical interfaces, but also bundles the machine and control technology expertise into fewer hands. Moreover, it increases availability when it comes to service and maintenance work.