The customer was previously using a competitors product which never worked properly.
Power plants use fuel oil of various grades and qualities to preheat the boiler when attempting to fire from a cold start. The amount of fuel oil burned is measured for a variety of reasons, but primarily for reporting to the environmental agencies.
The fuel oil is pumped into burners, and any unburned oil is returned to storage tanks in a seperate pipe. Often 2 meters are required in order to measure both the amount of oil pumped into the burners and the amount of unburned oil. The net difference between the meters is then the amount consumed and reported.
The 4 unit coal burner has several different power companies holding stake in the 4 units. The percent ownership varies from unit to unit. The fuel oil for all 4 units is stored in a central area, so the net consumed by each unit must be measured, accounted for and billed to the various owners according to their share owned.