INTRODUCTION

Optimiser processes seek to attain optimal operating criteria (for example :- lowest fuel usage, fastest dellivery route etc.) whilst satisfying a set of rule bound operating conditions (e.g. maximum and minimum pressures, number of compressors to be used, max / min compressor speeds, valves to remain within an operating control band. load sharing across sites etc.). Any parameter can effectively be optimised with the most common processes being pump / compressor optimisation, throughput optimisation, temperature optimisation and sump optimisation.

Pump / Compressor Optimisation can consider individual station configurations or complete pipeline / network configurations to optimise the unit configuration in terms of fuel usage. The user specifies the required output flowrates and the input pressure and temperature and defines whether pumps / compressors are available or not. The optimiser exhaustively searches every combination of pump / compressor and control valve settings whilst ensuring that it satisfies the predefined rules until the optimal compressor and control valve settings are determined. The output from the compressor optimiser is a ranked list of the most efficient pump / compressor and control valve setpoint configurations for each station.

Sump Optimisation

The pump start / stop optimisation process is used within the water industry to optimise the pump start and stop levels within the sump. Pumps are frequently set to start and stop at the highest and lowest possible levels in the belief that minimising the number of pump starts and stops results in minimised power usage. In certain cases, extending the start and stop levels will improve efficiency of operation but allowing the water level to fall to its minimum level every time the pump starts means that the static head between the sump level and the discharge location is always maximised. The energy required is at its maximum when the water level in the sump is at its minimum. If the stop level is optimised, taking into account the inflow to the sump, and pump operating efficiency, energy usage levels can also be optimised. By connecting the optimiser to the load forcaster, future expected conditions can be taken into account further improving the efficiency of performance.