When the steam is output from the boiler at high pressure and then transported to the steam point of each equipment, it is usually controlled by a pressure reducing valve. Why does steam need valve decompression?
1. The boiler usually produces high-pressure steam, which can reduce the size of the boiler, reduce the occurrence of wet steam, improve the dryness of the steam, and carry out long-distance transportation.
2. It is caused by the density change of steam. The steam density is high at high pressure. The pipeline of the same diameter can transport high-pressure steam more than low-pressure steam. The use of high-pressure steam transmission will reduce the size of the pipeline and save costs.
3. Condensation phenomenon occurs when steam is used. The decompressed steam reduces the pressure of condensed water to avoid the loss of flash steam when condensed water is discharged, and the energy loss of condensed water discharged under 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 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 condensed water to generate low-pressure flash steam, the purpose of energy saving is achieved. When the generated flash steam is insufficient, it is necessary to generate low-pressure steam supplement through the 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 is 1839kJ/kg at 2.5MPa and 2014kJ/kg at 1.0MPa. 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 the application equipment. First of all, you need to understand the basic categories of steam pressure reducing valves and their respective advantages and disadvantages.