Reducing Plant Energy Consumption

In an earlier post, Identifying Components then Optimizing Industrial Energy Consumption, we discussed how energy optimization initiatives were affected by what could be measured. Emerson’s Jonas Berge added a great comment to that post, which I will share here to bring it greater visibility.

Emerson's Jonas Berge


Running fans at excess speed, failed steam traps, fouling, inefficient combustion, pipe leaks, poor insulation on steam and condensate lines, relief valve leaks, tank leaks, unused equipment not turned off, valve leaks, and valves left open are some of the other reasons why plants are consuming more energy than they should. Poor combustion control, especially when fuel heat content changes, wastes energy by causing excessive stack losses. Leaking compressed air systems and valves left open, when not producing, waste the electricity that was consumed to compress the air.

Leaking steam systems waste the fuel that was consumed to generate the steam. Pumps and fans left on, when not producing, waste electricity. Water leaking and condensate not recovered waste the water itself plus the chemicals and energy required to treat it.

Most plants today only measure the energy streams in a single point at the source; where water, gas, and electricity enter the plant, from the air compressors, from the steam boiler, and from the utilities plant etc. Therefore, there is no visibility if there are leaks in an area somewhere in the plant, if consumption is higher than normal in some plant unit, or if some equipment is running when not needed.

By only looking at overall plant energy consumption, problems cannot be pinpointed so there is little or nothing that can be done to improve and sustain. Thus energy managers at most sites do not have the information they need in order to drive an energy management practices according to ISO 50001 to reduce reduction in energy consumption and losses. Whatever little data is available from the control system is infrequently put into spreadsheets manually.

Energy management is not just about electricity

There are many energy streams flowing through a plant and all have to be accounted for in order to get a complete picture. By modernizing with additional flowmeters and wireless electric power meters at the plant area, unit, and equipment levels together with an Energy Management Information System (EMIS) plants get the ability to manage consumption and loss of energy around the plant with much finer granularity.

Energy streams are measured for each plant area and each unit as well as for equipment with high consumption. There are five principal energy streams in plants: Water, Air, Gas, Electricity, and Steam (W.A.G.E.S), plus some others such as H2, N2, and CO2 depending on the type of plant.

For air and other gases, the pressure is also measured. Some of the required measurements may be available from the DCS. The missing measurements must be added.

Instrumental-to-SuccessA large number of transmitters have to be deployed plant-wide metering to enable data-driven energy management. Note that these additional measurements feed directly into the historian and EMIS software; they need not go through the control system. Essential plant systems such as the water system, compressed air system, fuel gas system, electrical system, and steam system are all fully monitored. Flow readings can also be used for water balancing and other energy balances, that is, matching total energy production precisely against areas of consumption. Orifice plate or Annubar slip between existing flanges or, if flow cannot be interrupted for installation, clamp-on ultrasonic flowmeters with WirelessHART adapters are used.

See further explanation in this article: Instrumental to Success.

Measurement alone doesn’t reduce energy consumption, but measurement enables excess consumption to be detected and investigated such that action can be taken. Since the flow of energy around the plant is measured with finer granularity, the energy manager gets the ability to detect and pinpoint overconsumption and leaks to a particular plant area, unit, or even an individual piece of equipment and investigate why.

This in turn allows plants to uncover leaks, combustion inefficiencies, and equipment running when not necessary etc. By settling these issues sooner, plant can improve and sustain energy affiance to further reduce their energy costs.

Here are two more relevant articles:

From Jim: You can connect with other energy management experts in the Industrial Energy group in the Emerson Exchange 365 community.

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