27

2022

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07

Why do steam pipelines need pressure reducing valves to reduce pressure?

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When the steam is output from the boiler at high pressure and then transported to the steam point of each equipment, pressure reduction control is usually performed.

When the steam is output from the boiler at high pressure and then transported to the steam point of each equipment, pressure reduction control is usually performed.

 

Why does steam need to be decompressed? The main reasons are as follows:

 

1. Boilers usually produce high-pressure steam, which can reduce the size of the boiler, reduce the occurrence of wet steam, improve the dryness of the steam, and transport it over long distances.

  

2. Caused by changes in the density of steam. The density of steam is high at high pressure. Pipes with the same diameter can transport more high-pressure steam than low-pressure steam. Using high-pressure steam transmission will reduce the size of the pipeline and save costs. 

 

3. Condensation will occur when steam is used. The decompressed steam reduces the pressure of the condensed water to avoid losses caused by flash steam when the condensed water is discharged. The energy loss of the condensed water discharged at low pressure is small.

 

4. Since the temperature and pressure of saturated steam are corresponding, a pressure reducing valve will be installed in the sterilization process and the surface temperature control of the papermaking dryer to control the pressure, thereby controlling the temperature of the process equipment.

   

5. Process equipment has its own design pressure. When the supplied steam pressure exceeds the demand of the process system, it needs to be depressurized. Some systems use high-pressure condensed water to generate low-pressure flash steam to achieve energy saving purposes. When the generated flash steam is insufficient, it is necessary to generate low-pressure steam through a pressure reducing valve.

  

6. The steam load of the boiler can be reduced because the heat enthalpy of steam is higher at low pressure. The heat enthalpy value is 1839kJ/kg at 2.5MPa and 2014kJ/kg at 1.0MPa. Therefore, low-pressure steam is more suitable for equipment use.

 

 Regarding the use of steam pressure reducing valves, users are particularly concerned about how to use them well and how to meet the actual needs of the application equipment. First, you need to understand the basic categories of steam pressure reducing valves and their respective advantages and disadvantages.