Inverted low pressure heater
key word：Heat exchange element
Category:
Product description
Inverted low pressure heater
1. Introduction
1.1. Application
Inverted low-pressure heater is a low-pressure heating device with inverted installation structure, which is an important auxiliary equipment of power station regenerative system. The heat exchange area of low-pressure heater equipped with 300MW steam turbine is 500-1100m2, and condensation section, cooling section and superheating section are set according to different needs.
1.2. Model meaning
DJ-**-##
DJ --- Code of low pressure heater
** -- Heat exchange area (m2)
## --- Form (inverted)
1.3. Structural features
The inverted low-pressure heater is an inverted vertical type, and the water chamber and shell are connected by contraction joint, which can reduce the volume of water chamber and make the heater compact in structure or small in floor area under the premise of ensuring sufficient heat exchange surface. At the same time, the tube sheet thickness and equipment quality can be reduced.
The shell side and tube side safety valves with appropriate capacity are selected to ensure the structural safety of the low-pressure heater. At the same time, the low-pressure heater is equipped with water level alarm device and local drainage control valve to ensure the normal water level of the low-pressure heater and the reliable operation of the unit under various working conditions. The water level control and alarm equipment of the low-pressure heater is not directly connected to the shell, but is installed on the water level cylinder, which is connected to the shell of the heater. This structure can make the water level of the low-pressure heater stable and convenient for maintenance and transformation.
There are two or more steam inlets of the product, which are arranged according to the thermal equipartition line at the same time. In this way, the steam inlet is relatively small and the steam inlet is even, which is conducive to heat exchange. There are three exhaust ports to make the heat load uniform.
2. Main technical parameters and product appearance
2.1. Main technical parameters (see table 19-1)
Table 19-1 main technical parameters of inverted low pressure heater
| Item | #4 Low pressure heater | #3 Low pressure heater | #2 Low pressure heater | #1 Low pressure heater |
| Number of heaters | 1 | 1 | 1 | 1 |
| Heater type | Inverted vertical | Inverted vertical | Inverted vertical | Inverted vertical |
| Heater support | Oval | Oval | Oval | Oval |
| Head form | Oval | Oval | Oval | Oval |
| Head material (water side / steam side) | 16Mn/20g | 16Mn/20g | 16Mn/20g | 16Mn/20g |
| Head thickness (water side / steam side, mm / mm) | 12月24日 | 12月24日 | 12月24日 | 12月24日 |
| Shell of the heater | ||||
| Max. OD of the shell/wall thickness（mm/mm） | 1424/12 | 1424/12 | 1424/12 | 1424/12 |
| Max. total length（m） | 11.33 | 10.62 | 10.2 | 11.55 |
| Max. operating space（m） | 8.9 | 8.2 | 7.5 | 8.8 |
| Shell material | 20g | 20g | 20g | 20g |
| Impact plate material | 1Cr18Ni9Ti | 1Cr18Ni9Ti | 1Cr18Ni9Ti | 1Cr18Ni9Ti |
| Bundle of the heater | ||||
| Heater tube side process | 2 | 2 | 2 | 2 |
| Connection mode between tube and tubesheet | Expanding joint | Expanding joint | Expanding joint | Expanding joint |
| Form (elbow or straight pipe) | Elbow | Elbow | Elbow | Elbow |
| Number of tubes | 962 | 660 | 661 | 661 |
| Tube material | 304L | 304L | 304L | 304L |
| Dimension × wall thickness (mm × mm) | ∮16×0.8 | ∮16×0.8 | ∮16×0.8 | ∮16×0.8 |
| Allowable number of blocked pipes | 19 | 13 | 13 | 13 |
| Water chamber and tubesheet | ||||
| Connection mode of water chamber and shell | Welding | Welding | Welding | Welding |
| Water chamber material | 16MnR | 16MnR | 16MnR | 16MnR |
| Tubesheet material | 20MnMo-1 | 20MnMo-1 | 20MnMo-1 | 20MnMo-1 |
| Tube sheet thickness (mm) | 120 | 110 | 110 | 110 |
| Short nozzle material | 20 | 20 | 20 | 20 |
| Connection mode of tubesheet and water chamber | Welding | Welding | Welding | Welding |
2.2. Product appearance (see Figure 19-1 and table 19-2)
Table 19-2 dimensions of inverted low pressure heater
| Low pressure heater | #4 | #3 | #2 | #1 |
| Maximum OD and wall thickness of shell (mm / mm) | 1424/12 | 1424/12 | 1424/12 | 1424/12 |
| Max. total length (m) | 11.33 | 10.62 | 10.2 | 11.55 |
3. Selection method
According to the heat balance diagram provided by the steam turbine plant and the installation position, heater form, heat exchange tube material, lifting height (core pulling distance), etc., the thermal and structural calculation is carried out to determine the cooling area.
4. Scope of supply
Low pressure heater assembly (including #4 ~ #7 low pressure heater support, anchor bolt, manhole, pipeline, accessories, counter flange of each interface, water level measuring device of low pressure heater, matching valve and control equipment) and auxiliary equipment.
The auxiliary equipment includes shell side safety valve and connector, pipe side safety valve and connector, shell side continuous and vent throttle orifice, shell side start-up vent valve, shell side drain valve, magnetic flap local water level gauge (including connecting valve), pressure gauge, thermometer, remote transmission interface of low-pressure heater water level measurement and differential pressure switch interface; Low pressure heater electric normal drain control valve and pneumatic emergency drain valve (on / off type).
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