Howard Wells, Danbury, CT

Various heat exchangers are used to capture waste heat contained in boiler exhaust that would otherwise be lost to the atmosphere. These devices are designed to capture the maximum amount of heat possible, resulting in improved fuel efficiency and reduced operational costs. There are three main types of heat exchangers used in boiler applications: economizers, air preheaters, and steam superheaters.

Economizers are heat exchangers that transfer heat from the boiler exhaust gas to the “feedwater” that goes into the boiler to produce steam. By transferring this heat to the feedwater, economizers preheat the water entering the boiler. This process reduces the energy required to raise the water temperature, resulting in significant fuel savings. Economizers are particularly effective in high-pressure boilers, where the waste heat recovery potential is substantial.

Air preheaters, as the name suggests, preheat the combustion air supplied to the boiler. They recover heat from the flue gas and transfer it to the incoming air. Preheating the air reduces the energy needed for combustion, which improves fuel efficiency and reduces emissions. Additionally, preheating the air helps maintain more stable and controlled combustion conditions, leading to reduced emissions and better combustion efficiency. Air preheaters also contribute to the prevention of excessive flue gas temperatures, which can cause corrosion and damage to the boiler.

Steam superheaters are used to raise the temperature of steam above saturation temperature. This is done both to increase the thermal energy of, and remove moisture content from, the steam. This dry and extra hot (i.e., “superheated”) steam offers several benefits, including improved turbine performance, reduced moisture-related issues, enhanced control over temperature and pressure, and increased system efficiency. Steam superheaters are commonly utilized in power plants, refineries, and industrial applications where high-quality, dry steam is essential for optimal performance.

The integration of economizers, air preheaters, and steam superheaters in boiler applications leads to enhanced energy efficiency, reduced fuel consumption, and lower greenhouse gas emissions. These components effectively utilize waste heat and optimize the heat transfer process, resulting in substantial operational benefits.