The energy consumption of an oil treatment machine is most easily reduced to a single division on the data sheet: total power divided by flow rate. That ratio is useful for comparing different models side by side, but it is not the electricity bill. The money actually paid depends on what the site produces: how much electricity the machine used over a given period, and how much oil it processed. How those two figures are recorded, and which steps push the ratio up, has to be clear before anything can be compared.
What the nominal ratio can do
The data sheet gives figures at rated conditions. The ZYD-100 has a flow rate of 6000 L/h and a total power of 72 + 5 kW; the LY-200 has a flow rate of 4800 L/h and a total power of 11 kW. Set these two sets of figures side by side in one table and at least the difference in structure becomes visible: a plate and frame filter press does not degas by vacuum, and its power sits in a different range from that of vacuum degassing equipment.
The TYA-50 has a flow rate of 2000 L/h, the TYA-100 is 4000 L/h and the TYG-100 is 6000 L/h, and the power of these models is to be read from their own nameplates. Put these groups of figures into one table on the same basis and the purchasing stage at least gives a clear picture: which kind of machine draws more power by nature, and which kind has an energy consumption that follows directly from how deep the treatment goes.
Why the measured value sits above the nominal one
- The warm-up phase. While the machine climbs from ambient temperature to the temperature control range, it is heating but not processing oil: the electricity has been spent and the tonnage has not yet been produced.
- Keeping warm while idle. When a short stop is ended by keeping the heater on, the electricity runs while the throughput is zero.
- The load on the vacuum system. The lower the vacuum demanded and the stricter the gas content requirement, the more work the extraction system does, and this part of the energy consumption varies with the conditions.
- The time before and after the batch. Between the oil entering the tank and leaving it there are element changes, waiting and cleaning; whether that time counts towards the energy figure depends on the basis of the statistics.
The four items to record on site
| What to record | Which reading to take | The usual mistake |
|---|---|---|
| Electricity | The start and end readings of the meter on the machine circuit | Counting the consumption of the whole distribution board |
| Throughput | The oil actually taken in for that batch, or the oil delivered converted to mass by density | Back-calculating from the rated flow rate on the data sheet |
| Running time | The actual time from oil entering to oil leaving | Mixing the waiting time before and after into the figure without saying so |
| Basis of the statistics | Whether the energy of the warm-up phase counts towards this batch | Different batches on different bases, so nothing can be compared at the end |
Making the two figures line up
A ratio only means something when the basis is the same. One machine, one type of oil and a statistical period of the same length are the minimum requirement for alignment; to compare against another machine, both sides have to be pulled onto the same kind of duty, for instance counting only the steady processing phase and only one type of oil.
There is one more thing that is easily overlooked: oils differ in density, so a tonne of oil and a cubic metre of oil are not the same quantity. Whether the statistics are kept in volume or in mass has to be settled once, because accounts that change basis half way through cannot be aligned.
Once this account is clear, the levers become clear as well: how the heating range and the heating time are set, how long the vacuum system runs, and whether the machine is kept warm or cut off completely while it is not producing. All of these are choices in daily operation, and none of them requires a different machine.
Energy per unit of oil can only be compared on the same basis, and the basis is only obtainable on site.
