30 Explanations of Professional Terms for Steam Turbine
Time: 2025-04-08
- Temperature: Temperature is a measure that indicates how hot or cold an object is.
- Saturation temperature: When water is heated at constant pressure, the temperature at which the water begins to boil is usually called the "saturation" temperature, that is, the boiling point.
- Pressure: The vertical force applied per unit area is called pressure.
- Absolute pressure: Whether it is positive pressure or negative pressure, the real pressure of the gas in the container is called absolute pressure. It is denoted by P absolutely. Absolute pressure = gauge pressure atmospheric pressure.
- Heat conduction: In the same object, the process of heat transfer from the high temperature part to the low temperature part, or when two solids with different temperatures are in contact with each other, the heat transfer from the high temperature part to the low temperature part is called heat conduction.
- Convection: When a fluid (gas, vapor or liquid) and a solid wall come into contact, the heat transfer process between each other is called convection heat release.
- Thermal radiation: It is the process by which high-temperature substances transfer heat to low-temperature substances through electromagnetic waves. This heat exchange phenomenon is fundamentally different from heat conduction and heat convection, which not only produces energy transfer, but also is accompanied by the transfer of energy forms, that is, from heat energy to radiant energy, and then from radiant energy to heat energy.
- Rankine cycle: the feed water entering the boiler is heated at constant pressure and becomes dry saturated steam, and then becomes superheated steam through the heater, and then in the steam turbine adiabatic expansion to do work, the exhaust steam enters the condenser at constant pressure and release, condenses into water, and then enters the boiler through the feed pump adiabatic compression, and then forms a cycle back and forth, which is called the Rankine cycle.
- Recuperation cycle: The so-called feedwater heating is to use part of the steam extracted from an intermediate stage of the steam turbine to heat the feedwater, and the cycle with feedwater recuperation is called "recuperation cycle".
- Intermediate reheat circulation: Intermediate reheat circulation is to lead the steam that has done work in the high-pressure cylinder of the steam turbine to the intermediate reheater of the boiler for reheating, so that the temperature of the steam is increased again, and then it is led to the medium pressure cylinder of the steam turbine to continue to do work, and the final exhaust steam is discharged into the condenser. This thermal cycle is called an intermediate reheat cycle.
- Impulse steam turbine: Impulse steam turbine refers to a steam turbine in which steam expands only in the nozzle to do work. In an impulse steam turbine, the steam does not expand in the blades to do work, but only changes the direction of the steam flow.
- Reactionary steam turbine: Reactionary steam turbine refers to a steam turbine in which steam not only expands in the nozzle to do work, but also steam expands in the blades to do work. The moving blade is not only subjected to the impact force of the steam flow, but also by the reaction force generated by the expansion and acceleration of the steam in the moving blade.
- Condensing steam turbine: Condensing steam turbine refers to the unit in which the steam entering the steam turbine is condensed into water and returned to the boiler for reuse after the steam entering the steam turbine is worked.
- Back-pressure steam turbine: Back-pressure steam turbine refers to the steam that enters the steam turbine to do work, exhaust steam for all heating users, such as industrial production, heating, etc., this kind of steam turbine is characterized by the exhaust pressure is greater than the atmospheric pressure, called the back pressure steam turbine.
- Intermediate reheat steam turbine: The intermediate reheat steam turbine is to lead the steam that has done work in the high-pressure cylinder of the steam turbine to the intermediate reheater of the boiler for reheating, so that the temperature of the steam is increased again, and then it is led to the medium pressure cylinder of the steam turbine to continue to do work, and the final exhaust steam is discharged into the condenser.
- Regulating stage of steam turbine: The first stage of the steam turbine adjusted by nozzle is called regulating stage.
- Speed stage: The first stage of the steam turbine with door throttling adjustment is called speed stage.
- Vacuum: When the pressure in the container is lower than the atmospheric pressure, the part below the atmospheric pressure is called vacuum. Vacuum = atmospheric pressure - absolute pressure.
- Vacuum: It is generally believed that the percentage of the ratio of vacuum to atmospheric pressure is called vacuum.
- Ultimate vacuum: The vacuum of the condenser mainly determines the temperature and flow rate of the cooling water, and the vacuum is mainly increased by reducing the temperature of the cooling water or increasing the flow rate. When the vacuum of the condensate is increased, the steam expands in the final blade, if the back pressure is very low, it may expand in the bevel cutting part, the back pressure is reduced again, and the expansion exceeds the bevel cutting part and does not play a role, then the work of the steam turbine will not increase, that is, the vacuum at this time reaches the ultimate vacuum.
- The most economical vacuum: the so-called "most economical vacuum" is that under the given heat load of the condenser and the inlet temperature of the cooling water, the amount of cooling water is increased, the vacuum of the condenser is increased, and the output of the unit is increased △Nd, but at the same time, the power consumed by the cooling water is also increased △a, then the difference between △d and △a is the most economical vacuum when the cooling water is the maximum.
- Thermal stress: When the temperature inside the object changes, as long as the object cannot expand and contract freely, or its interior is constrained by each other, stress is generated inside the object, and this stress is called thermal stress.
- Thermal shock: The so-called impact refers to the large amount of heat exchange between the steam and the metal parts of the steam turbine in a short period of time, the temperature of the metal parts rises in a straight line, the thermal stress increases, and even exceeds the yield limit of the material, and in serious cases, it even causes damage to the components.
- Thermal fatigue: When metal parts are repeatedly heated and cooled, a large temperature difference will be generated inside them, causing a large impact thermal stress, this phenomenon is called thermal fatigue.
- Thermal deformation: The deformation of parts caused by temperature change is called thermal deformation.
- Degree of reaction: It is the ratio of the ideal enthalpy drop Hb of steam falling when it expands in the moving blade to the ideal enthalpy drop H1 of the whole stage.
- Critical speed of rotor: when the turbine generator reaches a certain speed, the unit vibrates violently, and when the speed leaves this speed value, the vibration weakens rapidly to return to normal, and the speed that makes the steam turbine unit produce violent vibration is called the critical speed of the rotor of the steam turbine generator.
- Hard shaft: The critical speed of the steam turbine rotor is above the working speed, which is called the hard shaft, also known as the rigid shaft.
- Flexible shaft: The critical speed of the steam turbine rotor is below the working speed is called the hard shaft, also known as the flexible shaft.
- Axial elastic displacement: The axial elastic displacement of the steam turbine does not refer to the thrust clearance, but the axial elastic displacement is due to the elastic deformation of the thrust disc and the thrust pad, the bearing seat and gasket behind the working pad when the load of the steam turbine increases and the thrust increases. Under the condition that the steam parameters and vacuum remain unchanged, there is a certain axial elastic deformation corresponding to the different loads of the steam turbine, which is called the axial elastic displacement of the steam turbine.
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