In order to ensure the safe, economical and flexible in operation and power plant thermal system usually consists of several interaction, coordination, and the different functions of subsystems, are mainly intermediate reheat steam system of regenerative system, water supply, external heating systems, waste heat recovery system, evaporator, bypass system and drain system.

 

Steam intermediate reheating system

The steam is removed from the intermediate stage of the turbine, reheated in the boiler reheater, and then sent back to the system at the lower stage of the turbine to continue work. The purpose is to increase the initial pressure, so that the steam steam tail of the steam turbine humidity will not be too large, to ensure the long-term safe work of the steam turbine. A primary or secondary intermediate reheat system may be installed depending on the degree of pressure increase. In order to improve thermal economy in modern thermal power plants, boiler steam turbine units are mostly of ultra-high pressure (~ 13 mpa) or above, so steam intermediate reheat system is mostly adopted.

 

Feedwater regenerative system

Steam is pumped from intermediate stages of the turbine at different pressures to heat condensate and feed water systems. It is one of the main measures to improve thermal economy of thermal power plant. Modern thermal power plants usually adopt 7 ~ 8 (even 9) regenerative heating system.

 

External heating system

A system that USES steam turbines to provide heat to the outside world.

 

Waste heat utilization system

A system for recovering heat from steam and drainage in a power plant. The aim is to reduce working fluids and heat loss. It mainly includes steam turbine shaft seal cooler, continuous discharge expanding container of natural circulation drum furnace and sewage discharge cooler.

 

Evaporator system

A system that USES evaporators to produce boiler feed water for power plants. High pressure drum boiler and dc boiler require highly pure supply water, in the past, the general use of evaporator distilled water. In other words, the intermediate extraction steam of the steam turbine is heated to soften the water and make it evaporate, and the generated secondary steam is cooled and condensed into water as the supply water in the regenerative system. This system has been gradually replaced by chemical water treatment technology because it increases the complexity of the thermal system and equipment investment and reduces the thermal economy.

 

Bypass system

A system in which all or part of the steam produced by the boiler bypasses the steam turbine or superheater and is discharged directly into the condenser or atmosphere after temperature reduction and pressure reduction. Its function is to coordinate the unbalance of boiler steam production and turbine consumption when the unit starts, stops and accidents occur, protect the steam turbine and reheater, improve the starting and load characteristics of the unit, it has the triple functions of starting regulation, safety protection and recovery of working medium. Bypass systems usually have superheater bypass, steam turbine bypass and three valve bypass and other types.

 

Hydrophobic system

A system used to remove condensate from steam equipment and pipes and overflow from water containers. It can ensure the normal working condition of the equipment and reduce the working medium loss in the thermal system. There are two kinds of starting hydrophobic and frequent hydrophobic.