WILLIAM Livoti from Baldor Electric has written an overview of the System Optimisation process.
System Optimization is an evaluative process which determines how well the equipment is matched to the system.
For many industrial facilities, a lot of energy is consumed in pumping fluids. Operators of pumping systems are often unaware of the energy efficiency of this equipment.
In large industrial facilities, it is common to find several hundred pumping systems. Of these, a few are critical to overall production. The function of these critical systems can affect large parts of the facility. The amount of energy consumed varies considerably from system to system.
A general rule of thumb is to set aside pumping systems that already employ adjustable speed drives or which use positive displacement pumps. The optimisation program should focus on fixed speed centrifugal units.
Pumping systems will exhibit a number of common symptoms if they are affected by improper sizing, selection, operation, or other issues. Common problem-prone systems include:
- Systems in which valves are throttled to regulate flow rate, level, pressure, etc.
- Systems that employ bypass flow regulation
- Systems which involve a batch type process, and in which one or more pumps operate continuously
- Frequent on/off cycling of a pump in a continuous process
- Presence of cavitation noise either at the pump or elsewhere in the system
- An equipment procurement policy that is based on lowest bid price
- A multiple parallel pump system in which the same number of pumps are always in operation
- A pumping system that has undergone a change in function, but with no change in pump equipment or operation
- A pumping system with no flow, pressure, or power indication.
If such systems exist, there is a likelihood that an optimisation effort will produce energy savings.
In making an assessment of how well optimized a system is, it is important to not just measure the existing system conditions, but to evaluate what is really required. This forms the benchmark basis on the optimization effort should proceed.
One of the first steps to optimisation is to understand the nature of the system, so as to best eliminate unnecessary energy losses in the system. Generally, pumps have a best efficiency point at a certain flow rate, after which efficiency drops off at higher flows.
According to Livoti, while using premium efficiency motors can yield improvements in efficiency and cost savings, the potential rewards are usually much less than those available from optimizing the pump and system.
By evaluating the total system and matching the equipment as necessary to maximum system efficiency, a System Optimisation process will result in optimum system reliability, reduced maintenance cost, energy savings and reduced down time.
However, in some cases, efficiency may not be the key factor required. In some industrial applications, reliability is a more important consideration than efficiency, even though reliability and efficiency are generally seen to be complimentary.
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