How much is the feed water of ultra supercritical DC furnace controlled by specific conductance

The supercritical pressure is generally the extension resistance + 10% margin = about 30MPa.

Ultra-supercritical pressure refers to the first-flow boiler, because only the first-flow boiler can use supercritical parameters, the three-phase point pressure of water is, the main steam pressure is greater than this pressure of the boiler is supercritical pressure, and when the main steam pressure is greater than 25MPa, it is called ultra-supercritical pressure boiler.

Variable pressure operation, also known as sliding pressure operation, is different from constant pressure operation, characterized by the fact that the steam turbine regulating steam valve is kept fully open during the load change of the unit, in order to reduce throttling loss, the boiler controls the load of the steam turbine by adjusting the main steam pressure, and the main steam temperature remains basically unchanged.

Now the bird is like the common 600,000 supercritical after the DC to see the temperature of the middle point, because the DC boiler is overheated in the water wall, the heat absorption of the mountain starter is fixed, and the temperature increase is also fixed, as long as the temperature of the middle point is watched, and then the control of the auxiliary desuperheating water can see the main steam temperature.

To put it simply: in general, the energy shield (enthalpy) of saturated water and saturated steam at the same temperature is different, and the latent heat of vaporization needs to be absorbed from saturated water to saturated steam, and the value is large. In the recritical state (about 22MPa) and higher pressures (i.e., supercritical), from saturated water to saturated steam, it is no longer necessary to absorb the latent heat of vaporization, that is, the enthalpy values of saturated water and saturated steam are the same.

In the boiler steam drum, the water is in a saturated state, and the saturated steam and water coexist, and there is heat and mass exchange when the same collision type occurs.

There is no such process in the boiler, so there is no need for a steam drum.

The main thing is to see how high the temperature is, and the higher the temperature, the more obvious the oxidation phenomenon. If the water is oxygenated, an oxide film can be formed on the pipe wall, which can inhibit the continued oxidation. However, there are also some phenomena of oxide scale peeling.

This is also the reason why some 600,000 and all million units choose oxygenation.

High conductivity indicates that the ionic content of the boiler make-up water is high, and the chloride ion is also high, and the boiler is highly concentrated, and the rate of scaling and corrosion will be accelerated. Normal boiler make-up water is demineralized water and desalinated water. Resin tanks are used outside the furnace to put water treatment chemicals.

This book focuses on the main theories and technologies in the design and operation of boilers for next-generation supercritical and ultra-supercritical units. including new technologies and economics for supercritical units; design characteristics and system layout of various types of supercritical and ultra-supercritical boilers; Flow characteristics and heat transfer characteristics of the water wall of the supercritical boiler spiral coil and the vertical pipe screen of the internal threaded tube, as well as the optimal design; Optimal control of supercritical boiler midpoint temperature and water-to-coal ratio; steam temperature characteristics and steam temperature regulation of supercritical boilers; Supercritical DC boiler starting system and air-smart start-up characteristics; Metal materials of the unit of Chaolinkai Judgment Boundary; New technology for pulverized coal combustion. The book also includes the design theory and operating characteristics of subcritical parameter boilers; Transformer operation of peak shaving unit and flame detection technology, etc.

Because of the high steam parameters of the ultra-supercritical unit, the endothermic distribution has changed compared with the subcritical unit. The water wall does not need to be circulated repeatedly to heat the working water, and the water can be evaporated in one process. The working fluid at the outlet of the water wall is already dry steam, and the steam drum has lost its meaning.