Different types of steam
蒸汽is generated by simply boiling water. But depending on the gas-vapor content of the steam and its temperature above the boiling point, we can define different types of steam for practical usage.
蒸汽T-H diagram(Temperature Vs Enthalpy) depicts the phase change of:
liquid water (1) -> boiling water (wet steam) (2-3) -> dry steam -> superheated steam (4)
Wet steam
As the name suggests, wet steam has water content along with the gaseous steam. For this reason the wet steam is at its boiling point. Any heat that is added to wet steam will be first used for boiling off remaining liquid water before the steam temperature can be raised.
蒸汽qualityis defined as the percentage gaseous content within the wet steam mixture. This is an important parameter to define the exact thermodynamic state of the steam mixture. Steam with more liquid content is then considered to be of lesser quality.
Dry steam
As per the name, there is no liquid water content in the dry steam. Since every water molecule is in vapor form, the quality of dry steam can be said to be of 100%.
Dry steam can be at or above the boiling point of the steam at given pressure.
Superheated steam
Superheated steamalso has 0 liquid content. In fact, steam is said to be superheated when it is heated above its boiling point temperature. This way additional heat supplied is raised by gas molecules for temperature raise.
Generally superheated steam is generated at the boilers to be used in many applications as a utility, wherever you want to avoid two phase flow in thesteam network pipes.
每当需要在沸点干蒸汽时，steam desuperheatercan be used to bring down the steam temperature at around 3 deg C above the boiling point.
Industrial applications of steam
蒸汽系统的工业应用，例如 - 蒸汽跟踪，蒸汽吹动，蒸汽锤打等。查看工业蒸汽系统的资源。
蒸汽Blowing- Cleaning by steam blowing is carried out essentially for steam circuits (i.e forsteam generating boilers, steam heated exchangers, steam turbine upstream piping or other steam lines). Due to problems of condensation of steam or draining of condensate, this type of cleaning has to be used with the utmost care, as it can potentially create vacuum in the equipments being cleaned.
蒸汽generating boilers- Boilers are basically vessels used for heating the water and converting it to steam, as the name suggests. Boilers vessels generally use an internal heat source for boiling the water. Generally the steam is used as a utility in process plants and needs to be available at certain temperature and pressure conditions. A boiler is designed based on the desired temperature pressure conditions of the product steam.
蒸汽hammering- Steam hammering is the phenomenon which occurs in steam charging in the pipeline while there is a presence of condensate in the line. This is because of sudden drop in pressure of steam as it comes in contact of condensate.
蒸汽network in a process plant- 自工业革命以来，蒸汽一直是传达能源的一种流行方式。蒸汽用于产生能力，用于工艺行业，例如糖，纸张，肥料，炼油厂，石化，化学，食物，合成纤维和纺织品。如果使用蒸汽来产生电力，则希望使用较高的压力和过热温度，因为在温度和压力下，蒸汽轮机更有效。如果蒸汽仅用于加热工作，则无需过热。过热蒸汽是不可取的，因为它导致较低的传热系数。
蒸汽tracing for piping and instruments- 蒸汽跟踪是通过在过程管道周围循环蒸汽来加热的热追踪。在工程学中，通常在管道和仪器图（P＆ID）或行列表上使用蒸汽跟踪的加热管道和仪器的需求。
