I. What is economizer
Economizer heating surface of boiler feed water is heated in the rear of the boiler flue , boiler feed water before entering the first through it to absorb the heat of the flue gas , reducing the flue gas exhaust temperature , saving energy , improving the efficiency of the so called economizer . ( The word comes from coal-fired boiler economizer , but the system is also used to refer to other fuels economizer )
Economizers are mechanical devices used to make the Heating Ventilation and Air Conditioning (HVAC) unit more efficient by regulating the return air and outside air. Economizers come in many different configurations.
II. Economizer Category
1 Degree water is heated by : Boiling can be divided into ( entering water temperature is the saturation temperature of the steam drum drum under pressure ) and non- boiling type ( entering water temperature is close to the lower drum drum pressure saturation temperature ) .
2 Press the manufacture of materials : There are two kinds of cast iron and steel pipe economizer . Boiling use more non- economizer made of cast iron , but also useful for steel pipe , and boiling economizer can only be made with steel . Cast iron economizer applied pressure ≤ 2.5MPa multi boiler . If the pressure exceeds 2.5MPa, made of steel should be used economizer .
3 in the form of device : There are two types of vertical and horizontal .
4 Press the relative flow of smoke and water supply points: a co-current , counter-flow and hybrid three.
5 According to the structure of the form : finned tubes economizer and economizer . Fin tube economizerinclude : H finned tube economizer ( used more ) and helical fin tube economizer .
III . Economizer role of an improved water temperature
1. reducing water wall stress and improve boiler evaporation ;
2 . Low-temperature flue gas heat absorption , reduce exhaust gas temperature, increase boiler thermal efficiency, fuel savings ;
3. Raising the temperature of the water into the drum will reduce the thermal stress caused by temperature differences , improve the working conditions of the boiler, to extend the service life of the boiler ;
4 . Since the first heated water into the drum before the economizer , thus reducing the water in the heating surface endothermic ,Economizer can be used to replace part of the high cost of heating surface evaporation .
IV . Economizer layout features
( 1 ) counterflow arrangement , increasing the temperature difference ;
( 2 ) water from the bottom up ( following the opening of the inlet pipe , outlet pipe on to ) , to facilitate the discharge of gas , to avoid corrosion ; fumes from top , the soot blowing effect.
V . Role economizer recirculation
In the boiler ( drum boiler ) to start the process, due to the circulation of its soda pipeline did not establish that the boiler feed water at a standstill, this time inside the water economizer is not flowing state , along with the strengthening of the boiler combustion , smoke improve the temperature of the water inside the economizer prone to vaporization , so that local economizer in over-temperature condition. To avoid this situation , from centralized under the water followed by a pipeline to the drum of the economizer inlet , as recirculation pipes, the water is flowing inside the economizer state . Avoid vaporization .
VI. Economizer hydrostatic test should be carried out before installation and bracket installation
Test pressure 1.25P +5 (P boiler working pressure ) no leakage is qualified. Meanwhile economizer safety valve adjustment . Valve opening pressure should be 1.1 times the working pressure of the device points , or 1.1 times the working pressure of the boiler . Location economizer bracket and rear elevation to find a good pouring of concrete , strength grade concrete foundation should be higher than the strength grade level, and should be tamped and Conservation ( when fresh concrete is best to use pisolite ) . When the concrete strength reaches more than 75% , the anchor bolts tightened. Economizer with three wooden tower or other lifting equipment will be installed on the bracket economizer and economizer inspection of imported equipment , the elevation is consistent with the boiler flue outlet and two parts distance and bolt holes are matched by adjusting bracket location and elevation , to the smoke pipe installation requirements