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Air preheating

Air Preheating

The main points

  • Required for high flue gas temperatures
  • Reduces flue gas loss by up to 10%
  • Suitable for all fuels
  • Very short amortization times of < 2 years possible
  • Easy to retrofit

Making good use of valuable residual heat

If the flue gas temperature of a process firing system is especially high, economizers can only be used under certain conditions. In these cases air preheaters can be used: They remove valuable energy from flue gas which would otherwise go unused up the funnel, using it instead to preheat the combustion air of the firing system. A preheater used in this position can save up to 10% on fuel and also lower the impact on the environment considerably.

Air preheaters of this type are typically located downstream from high-pressure steam boilers and thermal oil heater with a flue gas temperature that often reaches 350°C or more. The combustion air can be preheated to as much as 300°C in this case. The resulting high level of efficiency means amortization times are less than two years. Air preheaters are now used more frequently in low temperature ranges as well, for example in conjunction with calorific value technology.

SAACKE air preheaters are individually adapted to specific tasks. They work mostly in cross-counterflow and are almost always designed as a tube bundle heat exchanger or plate heat exchangers. Rotary air preheaters are also used in large plants with high preheating temperatures.

The principle is the same for a new plant or retrofitting: All solutions are based on standardized components and can be implemented quickly, reliably and inexpensively. Different fuels and sulfur contents do not present an obstacle. Air preheaters are suitable for all standard and many special fuels. Optional temperature control can keep the flue gas temperature constant close to the dew point, thus increasing the efficiency of the system still further.

Depending on customer preferences and technical constraints, different aspects can be emphasized when designing air preheaters. For example, especially compact preheaters have low requirements for material and space, but they offer increased resistance and may therefore possibly require greater fan capacity. On the other hand, solutions that offer less resistance are almost always larger and heavier. Even if planning and design may emphasize different aspects, all SAACKE air preheaters are highly available, require little maintenance and offer uncompromising quality that significantly lowers the operating costs of the firing system.