“Energy Performance Indicators” are the factors that measure the plant energy consumption per unit of feed or product. Monitoring EPIs in a process plant provides an engineering tool to evaluate the overall performance of the operation mode. Moreover, it can be structured in a way that enables identifying the plant energy elephants and troubleshooting the overall plant economics. EPIs are also important to the financial modeling in order to evaluate the energy cost per unit of product.
Due to uncertainty and assumptions during hydraulics design of any process unit, Pumps and Compressors are normally sized with average of 20% over-design capacity. it is of the good engineering practice to revisit the pump design assumptions and size selection to evaluate compatibility to system requirement.
Controlling pump discharge flow or head is normally done via throttling the control valve downstream the pump which result in power losses on the motor and erosion damage on the valve.
Variable Speed Drives (VSD) is a more efficient solution to control both flow and discharge pressure of a pump or compressor. Decreasing the pump speed will decrease the discharge pressure and hence the flow as per the famous “Pump Affinity Law”.
Equipment Performance Monitoring is a key to evaluate the operation style and daily practice. Mechanical condition of each process equipment and its compatibility to the system requirements composes a matrix that leads to smooth and efficient operation.
Plant operation should extend its focus on production quantity and quality to operation efficiency or operation excellence. While production rate and specifications are solid target for the plant, efficient operation from energy point of view is the key factor in the product profit margin.