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Inverted low pressure heater

key word:Heat exchange element


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 thicknessmm/mm 1424/12 1424/12 1424/12 1424/12
Max. total lengthm 11.33 10.62 10.2 11.55
Max. operating spacem 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).