It is not interference, but flexibility, which is a mechanical term and refers to the ability of the bracket to withstand deformation and bending. Enthalpy is the state parameter of working medium, which indicates how much heat energy the working medium has. For steam turbines, steam expands in the nozzle, the pressure decreases, the speed increases, the heat energy is converted into kinetic energy of airflow, and the enthalpy decreases. The decrease of steam enthalpy is called enthalpy drop, which means the decrease of steam heat energy. Conversely, when steam or water is heated, its heat energy and enthalpy increase, which is called enthalpy rise.
Effective enthalpy drop, that is, when steam heat energy is converted into kinetic energy, do useful work and remove all kinds of lost parts. I hope it works for you ~
Question 2: What is the enthalpy drop of15mw steam turbine? You have to tell me the inlet and exhaust parameters of 15MW turbine before I can tell you the enthalpy drop. You should know that even the 15MW steam turbine has different inlet parameters, and the inlet parameters of different steam turbine plants are also different.
Question 3: Does anyone know the calculation method of enthalpy drop of steam turbine? Influence of parameter change of steam-driven feed water pump unit on main engine economy of 300MW unit
Zhai Peiqiang
(Henan Sanmenxia Huayang Power Generation Co., Ltd. 472 143)
Abstract: Most domestic 300MW thermal power units use small steam turbines to drive feed water pumps. The parameter changes of small steam turbine and feed water pump (steam-driven feed water pump group) have obvious influence on the economic operation of the main engine. Based on the analysis of a domestic 300MW unit, the relationship between them is given quantitatively.
Key words: steam-driven feed water pump group; Host computer; economy
Preface of 0
In the thermal power plant, the feed water pump is one of the indispensable equipment that constitutes the thermal cycle of the unit. Therefore, as an important auxiliary machine in the operation of the unit, its operation condition has obvious influence on the economy of the whole unit. However, when people analyze and evaluate the economic operation of the unit in daily life, it is often easy to ignore this factor.
There are generally two driving modes of feed water pump for 300MW thermal power units in China: small steam turbine driving and motor driving. But in practice, small steam turbines are mostly used to drive feed water pumps, and rarely driven by motors.
The following is an example to analyze the economic impact of the change of operation parameters of steam-driven feed water pump of domestic 300MW steam turbine unit.
1 overview
The domestic 300MW unit is a subcritical once intermediate reheat steam condensing unit with two cylinders and two rows, and the high and medium pressure cylinders and low pressure cylinders are symmetrically arranged. The high-pressure cylinder is provided with a first stage and a second stage of steam extraction, which respectively correspond to heaters #8 and #7; The intermediate pressure cylinder has three-stage and four-stage steam extraction, corresponding to #6 and #5 heaters respectively; The low-pressure cylinder is equipped with five, six, seven and eight stages of steam extraction, corresponding to #4, #3, #2 and # 1 heater respectively. Among them, #8, #7 and #6 heaters are high-pressure heaters, #5 heaters are deaerator, and # 1-# 4 heaters are low-pressure heaters.
The unit is equipped with two 50% steam-driven feed pumps, and the turbines driving the feed pumps can be supplied by high-pressure and low-pressure steam sources respectively or simultaneously. When the main engine is running normally, the low-pressure steam source of the turbine driving the feed water pump is taken from the fourth-stage extraction steam, and the high-pressure auxiliary steam source can also be used. The high-pressure steam source is new steam from the boiler. During the normal operation of the unit, the high-pressure steam source is hardly used. Therefore, the following low-pressure steam source is taken as an example for analysis.
2 feed water pump turbine's influence on the main engine's economy
1, the main steam flow of the unit is 935 t/h; The fourth stage extraction enthalpy is 3135.1kj/kg; The exhaust enthalpy of the unit condenser is 2355.7 kJ/kg, and the steam consumption of the feed water pump turbine is 33.984 t/h..
2. Reduced value of equivalent enthalpy drop of new steam (calculated by equivalent enthalpy drop method [1])
δH =αf(H5-HN)( 1)
Substituting the above correlation values can get:
δH =(33.984/935)×(3 135. 1-2355.7)= 28.3285 kJ/kg。
3. The economic value of equipment is reduced:
δηI =δH/(H-δH)× 100%(2)
Substituting the above correlation values can get:
δηI = 28.3285/( 1 184.3-28.3285)× 100% = 2.45%
4. Change value of unit coal consumption (take unit coal consumption value as 345g/kWh)
δBb = BbδηI(3)
Substituting the above correlation values can get:
δBb = 345×2.45% = 8.5g/kW？ h
3. The influence of the change of operation parameters of feed water pump group on the economy of main engine.
Drive feed water pump turbine ... >>
Question 4: How to calculate the ideal enthalpy drop of steam turbine when calculating the efficiency of high pressure cylinder of steam turbine? The ideal enthalpy drop is the enthalpy difference between the isentropic expansion line of steam from the inlet pressure and temperature point and the exhaust pressure line of high pressure cylinder.
Question 5: How does the enthalpy drop change with the increase of steam turbine load and flow? The enthalpy drop increases because the pressure and temperature of the regulating stage increase with the increase of the main steam flow, while the exhaust pressure and temperature are basically unchanged. So the enthalpy drop increases.
Question 6: How to calculate the stagnation enthalpy (isentropic enthalpy) of high pressure cylinder of steam turbine? For isentropic process, the outlet entropy is equal to the inlet entropy, and the isentropic enthalpy can be obtained according to the outlet entropy and outlet pressure. If the stagnation enthalpy is considered, the inlet velocity of steam can be considered, which can generally be ignored.