When the steam is output from the boiler at high pressure and then sent to the steam point of each equipment, the pressure reduction control is usually carried out. Why does steam need to be decompressed?
The main reasons are as follows:
1. The boiler usually produces high-pressure steam, which can reduce the size of the boiler, reduce the generation of wet steam, improve the steam dryness, and carry out long-distance transportation.
2. It is caused by the change of steam density. The steam density is high at high pressure. The pipeline with the same caliber can transport high pressure steam than low pressure steam. Using high pressure steam transmission will reduce the size of the pipeline and save costs.
3. Condensation occurs when steam is used. The decompressed steam reduces the pressure of the condensate, avoiding the loss of flash steam when the condensate is discharged, and the energy loss of condensate discharged at low pressure is small.
4. Since the temperature and pressure of saturated steam correspond to each other, pressure reducing valves are installed in both the sterilization process and the surface temperature control of the paper dryer to control the pressure, thereby controlling the temperature of the process equipment.
5. The process equipment has its own design pressure. When the supplied steam pressure exceeds the demand of the process system, it needs to be decompressed. When some systems use high-pressure condensate to generate low-pressure flash steam, energy saving is achieved. When the flash steam produced is insufficient, it is necessary to generate low-pressure steam supplementation through a pressure reducing valve.
6. The steam load of the boiler can be reduced because the enthalpy of steam is higher at low pressure. The enthalpy value at 2.5MPa is 1839kJ/kg, and the enthalpy value at 1.0MPa is 2014kJ/kg. Therefore, low-pressure steam is more suitable for equipment use.
For 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 application equipment. First, you need to understand the basic categories of steam pressure reducing valves and their respective advantages and disadvantages.
