Power Plant Boiler Air Preheater Reduce Heat Loss and Improve Efficiency 

Types And Features

The superheater can be divided into convection type, radiation type and half radiation type according to the heat transfer mode.According to the structural features can be divided into serpentine tube type, screen type, wall type and package wall type.They are made up of a number of parallel pipes and an inlet and outlet header.The outer diameter of the pipe is one

Generally 30 ~ 60 mm.The most common type of flow superheater is serpentine tube.It has a more intensive tube group, decorate in 450 ~ 1000 ℃ flue of the flue gas temperature, flue gas of vertical and lateral erosion.The flue gas mainly transfers the heat to the pipe by convection, and some of the heat is absorbed by radiation.The plate-type superheater consists of a plurality of tube screens, arranged in the upper part of the furnace or at the outlet, belonging to the radiation or semi-radiation type superheater.The former absorbs radiant heat from the furnace flame, while the latter also absorbs some convection heat.In power station boilers above 10 mpa, both screen type and serpentine type superheater are commonly used to increase heat absorption.The wall superheater applied on the inner wall of the furnace is radiant superheater, which is seldom used.The wall-mounted superheater is used in the large capacity power station boiler to form the wall of the furnace top and convection flue.The picture shows the arrangement of several superheater.The small capacity industrial boilers with superheater can meet the requirements only with single stage superheater.

Function

The changes of boiler operating conditions, such as load height, fuel change and combustion operating conditions, all have an impact on the steam temperature at the outlet of the superheater. Therefore, there are means to adjust the steam temperature at the outlet of the boiler in the power station to stabilize it at the specified value.The common means are as follows: water spray type or surface type temperature reducer is used to regulate steam temperature directly;The temperature of flue gas in the furnace is changed by the oscillating burner.Heat absorption of superheater is adjusted by flue gas recirculation (see steam temperature regulation of boiler).When the boiler load is increased, the steam temperature at the inlet and outlet of the flow superheater increases and that of the radiant superheater decreases.If the flow type, radiant type and semi-radiant type superheater are combined and configured reasonably, the outlet steam temperature change can be small when the load and combustion condition change.The heat absorption and steam flow of each parallel tube in the superheater tube group are different during operation.In order to avoid excessive temperature in individual pipes, superheater is divided into several pipe groups in large boilers. Steam of each pipe group is mixed with the collector box outside the furnace and transposed with the steam pipe to avoid excessive temperature difference between the pipes.

HD Boiler offers a best in class facility,including

• Fabrication area of 200,000 square meters
• 150 Engineers
• 600 Coded welders
• 60 Licensed Inspectors (including NDT level-lll instructors)
• Grade-ALicenses for Design and Manufacture boiler (issued by the State Administration of Quality Supervision and Inspection)
• ISO 90001:2008 Quality System
• ASME Certificate of Utility Boiler
• ASME‘S’ , ‘U’ and NB stamp authorization