Economizer

Economizer (English for preheater / economizer ) is a heat exchanger for recovery of waste heat from a variety of industrial processes.

Boiler plants

In the steam boiler technology of the economizer is ( briefly ECO) a " feedwater ". The flue gas passes through the economiser at relatively low temperatures, after it has given up its heat before the evaporator, superheater and intermediate superheater. The economizer uses the residual heat in the exhaust gases, which can no longer be made available from the boiler for physical reasons.

Shell boilers

For shell boilers of the economizer is either semi-mounted on the boiler or he forms a separate component. The flue gas from the last is fed to the economizer Kesselrauchgaszug. The flue gas temperatures at full load and are here not contaminated heating surfaces approximately 50 ° C - 80 ° C higher than the saturated steam temperature in the boiler. The allowable minimum flue gas temperature after the boiler is dependent on whether the fireplace towards the dew point (acids ) is stable. Therefore, often a temperature-controlled bypass valve is installed, the flue gas passes at too low a temperature to the Economisereinbauten over.

In the case of a boiler, which is regulated at a steam pressure of 10 bar, the usable temperature level in Eco is between 240 ° C and 140 ° C; this corresponds to a fuel saving of about 5%. The temperature of the feedwater would be increased in the case of 105 ° C ( according to the feedwater tank ) to about 135 ° C.

Water-tube boilers

In water-tube boilers, the economizer is integrated in the boiler and in the flue gas is the last heating surfaces before the air preheater where appropriate installed. With increasing pressure, the saturation temperature of water increases and the enthalpy of vaporization is lower. Therefore, with increasing boiler pressure increases the specific heat capacity, which can be transferred to the heat transfer through the Eco. At maximum pressure steam boilers that are driven with supercritical pressures, the term economizer and evaporator is unnecessary, since there is no more saturated steam condition is defined.

Refrigeration systems

In compression refrigeration systems are integrated economizer to increase the coefficient of performance. The refrigerant is compressed by a compressor and then condensed in the condenser. A side stream is taken from the main stream, which is released at an intermediate pressure. Main and auxiliary power is supplied to a heat exchanger. The refrigerant in the main stream is supercooled by the evaporating side stream. The secondary flow is pressure regulated and directed back to the suction side of the compressor. The increase in the coefficient of performance is refrigerant very depending of the used and the pressure level of the refrigeration system.

An alternative to the Eco subcooler is the incorporation of a central pressure cylinder in a two-stage compression refrigeration system. The liquid refrigerant from the condenser is passed through an expansion valve to the medium-pressure bottle. The vaporized refrigerant is sucked from the high pressure compressor is adjusted to the intermediate pressure.

See also recovery

Weblink

  • Economizer: http://www.loos.de/loos/fachber/049/fach21.pdf
  • Steam boiler technology
  • Refrigeration technology
Boiler (power generation)
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