Superheater And Reheater For Power Plant Boiler High Quality Reheat Furnace supercritical boiler
Power Plant Reheater Introduction
1. Reheater pipes are divided into two heating stages. First the cold reheat steam passes through the Low Temperature Reheater pipes, which shown by the name “LTRH” at the diagram. Furthermore, LTRH output steam flows to the pipes called Final Reheater.
2. The steam produced by the Final Reheater is then called Hot Reheat steam. Hot Reheat steam then goes to the low pressure steam turbine, so that the heat energy contained in it is converted into mechanical energy of the turbine shaft rotation.
3. Theoretically, the addition of one stage reheater utilization will increase the thermal efficiency of the rankine cycle by 3-4%, the addition of two stages of the reheater increases the efficiency by 1.5-2%, the addition of the three-stage reheater increases efficiency by 0.75-1%, and so on. Commonly, modern boiler only use one or two stage reheater.
Reheater Type & Characteristics
1. The diameter of the tube is generally 30-60 mm. It has a relatively dense pipe group, which is arranged in flue gas temperature 450 - 1000 C, and is scoured horizontally and vertically by flue gas.
2. The flue gas mainly convects heat to the pipe, and some radiation absorbs heat. The former absorbs the radiation heat of the furnace flame, while the latter absorbs part of the convective heat.
3. In power plant boilers above 10 MPa, both screen and serpentine tube superheaters are usually used to increase heat absorption.
4. The wall superheater applied on the inner wall of the furnace is radiation superheater, which is seldom used. The wall-enclosed superheater is used to form the top of the furnace and the wall of the convective flue duct in a large-capacity power plant boiler.
5. The light furnace wall is made of insulating material. The picture shows the arrangement of several superheaters. Small capacity industrial boilers equipped with superheaters usually use convective superheaters of single-stage tubes to meet the requirements.
Differences
| Type | Advantages | Disadvantages | Supporting method |
| Pendant-type | 1.Firm structural support | 1. Flow blockage by condensed steam 2. Needs slow restart to purge the water that accumulates in the bottom. | supported from above |
| Inverted-type | 1.Proper drainage of the condensed steam | 1. Lack the structural rigidity, especially in high speed gas flow | Supported from below |
| Horizontal -type | 1. Proper drainage 2. Good structural rigidity. | 1. They do not view the flam directly so they are mainly from the convective type | Usually supported in the vertical gas ducts parallel to the main furnace. |
Parameters
| Material | carbon steel, alloy steel , or durable heat steel |
| Tube OD | 10-114mm |
| Tube W.T. | 0.8mm- 15mm |
Detailed Picture
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Power Plant Reheater In Power Plant Two Heating Stages Increase Heat Absorption Images
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