An energy saving project is incomplete if it does not consider the energy and utility generation and distribution. In our workflow we regard the generation and distribution of the following utilities:
• steam (different pressure levels);
• electrical power (different voltages);
• water (for industrial use, demineralized water, cooling towers, chilled water, brine, condensate reuse, ultra pure water);
• air (for industrial use, instrumentation);
• nitrogen (pressurized).
A detailed view on this topic is given in Chapter 10 of this book, so here we will focus just on certain aspects we often observe in our saving projects.
Steam and electricity are generated in a power house which is operated by the customer himself or by an energy provider. In the case where the customer operates the power house, we will perform a technical analysis of the efficiency of the energy generation. In situations where steam and electricity are delivered by an external provider, we normally analyze the contracts in order to quantify the relation between consumption and price. In both cases (own powerhouse or provider) we often see a discontinuous relation between consumption and price. Turbines or generators can be operated in a certain range and deliver certain power. If the consumption goes beyond this range (because of additional demand or less consumption because of saving measures) the specific energy price will change stepwise.
An example: A customer wanted to increase the capacity of a plant, which was provided by its own power house. The proportional calculation of the energy demand with the capacity led to the investment in an additional gas turbine. We performed an energy efficiency project in parallel to the de-bottienecking project. The result was that the plant with extended capacity could be provided with steam and electricity by the existing turbines. We had to design some modifications in the power house, but the savings in comparison with a new turbine were enormous.
Also the utility distribution, for instance of steam, has to be investigated: a predictive maintenance program for steam pipes and steam traps are just a few measures that can save a lot of energy, reduce CO2 emissions and costs.
Some remarks concerning usage of water: normally the costs for water and therefore the driving forces for saving measures are lower than for steam or electricity (an exception is demineralized water or in particular ultra pure water in pharmaceutical plants). Nevertheless we analyze the consumption for instance of cooling water. In many cases there is no control valve on the cooling water side of heat exchangers. The hand valve instead is in position 'open') Here the installation of a process control in some cases makes sense, especially for closed cooling water circuits with cooling towers. If the customer wants to realize a capacity extension then cooling water savings can help to avoid investment in the cooling tower system.
For compressed air or nitrogen, last but not least, we detect leaks in the pipe system or open valves by special ultrasonic leak detectors that detect the gas leakages. The test is not costly and can result in easy savings.
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