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Horizontal low pressure heater

key word:Heat exchange element


Product description

Horizontal low pressure heater

 

1. Introduction

1.1. Application

The horizontal low-pressure heater is a low-pressure heating device with horizontal installation structure, which is an important auxiliary equipment of the regenerative system of power station. The low-pressure heater equipped with 300MW steam turbine has a heat exchange volume of 500-1100m2. According to different needs, the condensing section, the cooling section and the superheating section are set up respectively.

1.2. Model meaning

DJ-**-##

DJ -- Code of low pressure heater

**--------Heat transfer product (m2)

##------------Form (horizontal)

1.3. Structural features

In horizontal structure, the water chamber and the shell are connected by contraction joint, which can reduce the volume of water chamber on the premise of ensuring sufficient heat exchange area, make the heater structure compact, reduce land occupation, and reduce the thickness of tube sheet and equipment quality. If necessary, the last two stages of heaters can form a combined heater, which can be installed in the installation position of the condenser (exhaust device), reducing the occupation of land and providing convenience for the layout of the power station.

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, which can 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 20-1)

Table 20-1 main technical parameters of horizontal low pressure heater

Item #5 Low pressure heater #6 Low pressure heater #7 Low pressure heater
Number of heaters 1 1 1
Heater type Horizontal Horizontal Horizontal
Heater distribution Exhaust throat
Shell supporting type
Head form Oval Oval Oval
Head material (water side / steam side) 16MnR/20R 16MnR/20R 16MnR/20R
Cylinder length/ withdrawal length of core maintenance (m) 9 7 11.5
Shell material 20R 20R 20R
Impact plate material 1Cr18Ni9Ti 1Cr18Ni9Ti 1Cr18Ni9Ti
Heater tube side process 2 2 2
Connection mode between tube and tubesheet Expanding joint
Form (elbow or straight pipe) Elbow
Number of tubes 832 813 800
Tube material TP304 TP304 TP304
Pipe size × wall thickness (mm × mm) 16×0.8 16×0.8 16×0.8
Minimum wall thickness (mm) 0.72 0.72 0.72
Reduction of bending pipe outer arc processing (mm) 0.08 0.72 0.72
Minimum bending radius / calculated wall thickness of bending inner arc (mm) 0.72 0.72 0.72
Corrosion and wear allowance (mm)
Design required wall thickness (mm) 0.3 0.3 0.3
Wall thickness usded(mm) 0.8 0.8 0.8
Number of spare pipes 42 41 40
Connection mode of water chamber and tube sheet Welding Welding Welding
Material Q235B Q235B Q235B
Thickness (mm) 8 8 8
Connection mode of tubesheet and shell Welding Welding Welding
Water chamber material 16MnR 16MnR 16MnR
Nozzle material 20 20 20
Tubesheet material 20MnRo Forged 20MnRo Forged 20MnRo Forged
Thickness (mm) 100 100 110

2.2. Product appearance (see Figure 20-1 and table 20-2)

Table 20-2 dimensions of horizontal low pressure heater

Maximum outer diameter / wall thickness of shell (mm / mm) 1424/12 1424/12 1524/12
Maximum total length (m) 12.62 9.2 14.15

 

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 cooling area is determined.

 

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 vent 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 and differential pressure switch interface of low-pressure heater water level measurement, electric normal drain control valve of low-pressure heater and pneumatic accident drainage Water valve (on / off type).