Process heating uses the most energy in the manufacturing sector, averaging almost one-third of a facility’s total energy consumption. Monitor the heating process from start to finish and maintain the equipment to control energy costs.

In most fuel-fired heating equipment, the largest heat loss occurs when spent combustion gases are exhausted because these gases still contain a significant amount of thermal energy.

You can recover this waste heat and use it in processes such as preheating combustion air before it enters the system, preheating load material before it enters the heating process, steam generation for secondary processes, and water or space heating.

When heating systems exhaust hot combustion gases into ambient air that’s significantly cooler, negative pressure builds within the furnace. This allows cooler ambient air to infiltrate the furnace through the flue or leaks and other openings within the system.

This additional air will then be heated and exhausted, wasting energy and lowering system efficiency. Consider installing furnace pressure controllers to adjust the pressure within the furnace. This helps to maintain a positive pressure within the furnace, reducing cool-air infiltration into the heating system.

Motors consume almost 70% of the electricity used in the manufacturing sector. To eliminate energy losses, properly size and maintain the motors.

If the facility is heated, warmer air will naturally stagnate near the ceiling where it won’t do much good. Change the direction of ceiling fans to circulate the heated air vertically.

Though motors often operate under varying loads, they’re generally selected based on the highest anticipated load. This causes facilities to use more-costly motors than necessary and presents the risk of underloading them.

Consider selecting a motor based on the load duration curve (LDC) of its specific application rather than its highest anticipated load. The LDC shows the relationship between motor capacity and utilization, indicating the average load demand for the motor.

Motors selected according to an LDC will be smaller, less expensive, and more efficient over their lifetimes. They will, however, have a rating slightly below the highest anticipated load.

This method does risk overloading and overheating the motor, but most motor manufacturers design them with a service factor above the stated rate that allows motors to temporarily overload without harm.

By design, they’re very efficient and produce power at double the efficiency of power delivered from a central plant. Cogeneration systems are commonly found in plants with large heating or cooling needs.

Improve motor efficiency by upgrading to new, higher-efficiency models instead of rebuilding old motors. Rebuilding old motors may improve efficiency by 1 or 2 percentage points at most. The cost of electricity to operate a motor for its lifetime far exceeds its purchase price.

When loads change, variable-frequency drives (VFDs) alter the speed of a motor accordingly, often significantly reducing electrical consumption. You can install VFDs in most existing systems because they’re designed to operate standard induction motors.

VFDs might cause problems with power quality due to induced harmonic distortion. To mitigate these problems, explore harmonics filtering or other measures.

Boilers account for the largest non-process consumption of natural gas within the manufacturing sector. Optimised operational setpoints and regular maintenance will ensure boilers perform at their peak efficiency.

Take advantage of a boiler control system’s onboard efficiency strategies, such as outside-air reset and outside-air, high-temperature shutoff. If no controls exist, consider retrofitting boiler controls onto the system to optimize performance and eliminate unnecessary cycling.

A particularly effective control system measures real-time heat load using a flow meter and temperature sensors in conjunction with an advanced software algorithm to enable the boiler to deliver only enough heat to match the load. By reducing short-cycling losses, this control strategy can reduce boiler energy consumption by as much as 45%.

On average, stack loss from boilers is around 15%. Blowdown also produces waste heat that’s lost through drainage. Consider installing waste-heat recovery systems for both of these processes. You can use the waste heat from the boiler and stack to preheat the intake air or makeup water for the boiler.

Steam traps are automatic valves that release condensed steam from the boiler while preventing the loss of live steam. As with compressed air systems, an ultrasonic leak detector will reveal faulty steam traps. It isolates sound frequencies, compares the frequencies to those of a properly functioning steam trap, and shows the results to users via a digital display.

In facilities with more than one boiler, optimize load management across boilers and save energy by operating them at peak efficiency. As demand increases, use the most-efficient units first, and as demand decreases, cut the least-efficient boilers. Scheduling loads across boilers to minimize short cycling can also improve system performance.