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Consider process requirements and plant operating goals to determine the optimal heating source for your facility.
Most facilities in the chemical process industries (CPI) require some form of heat. The amount of heat required and the necessary level of consistency can vary from process to process. Engineers must decide on a heating source that works best for a particular process. Choosing the wrong type of heating source can have a variety of negative consequences. On the benign end, an inefficient heating source increases operating expenses. Inefficient heating may not achieve temperature setpoints, increasing waste or rejection rates and impairing quality. At the other end of the spectrum, frozen pipes and feedstock lines could trigger a plant shutdown.
Facilities commonly generate heat using electricity or steam. The goals of the plant and the nature of the process help to determine which heating source is best suited to the application. The process requirements will help guide the optimal heating approach. In some cases, the optimal approach may be a combination of steam and electric heating.
Steam heating systems
Steam is an efficient heating source that is also cost effective. The cost depends largely on the amount of heat required. If the plant's heat load is more than 1 MW (3.4 million Btu), a steam system is a realistic option; some steam boilers have a capacity exceeding 50 million Btu.
A steam system has four basic parts: a boiler, a steam distribution system, a heat exchange system, and a condensate return system (Figure 1). The heart of the steam system is the boiler - a pressurized chamber heated by a system of (typically gas-fueled) burners. Boiler design and construction is governed by the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) standard. Many different types of boilers are available; see the September 2017 CEP article "Boiler Project Fundamentals" (1).
Water enters the boiler and is heated to generate steam, which is categorized by its pressure. Steam is classified as low pressure when it is below 50 psi. Medium-pressure steam falls between 50 psi and 250 psi. Steam above 250 psi is considered high-pressure steam. At 250 psi, the temperature of steam is approximately 406°F. High-pressure systems are expensive to build and maintain; therefore,...