Aug 01, 2012 turbine generator maintenance 180,068 views. A method for starting a steam turbine comprising prewarming the steam turbine with a steam wherein at least 65% of an energy used to prewarming the steam turbine is derived from a latent heat energy of the steam. Steam has one great advantage over waterit expands in volume with tremendous velocity. Steam turbine, watersteam chemistry, stress corrosion cracking. Pdf portable document format pdf 68 care and maintenance. Steam turbine thermal modeling for improved transient. Next hp and ip stop valves can be opened, with control valves closed. A simplified steam cycle7, in this case with a drumtype boiler, is shown schematically in figure 1. New procedure speeds cold start, protects turbine power. The steam turbine rotor is the spinning component that has wheels and blades attached to it. This thesis addresses the thermal modeling of steam turbines. Following figures show steam process in steam turbine. The performance of the steam turbine is governed by the losses occurred in it.
Three basic phases can be distinguished in the process of steam turbine unit start. Figure 4 shows steam process in enthalpy against entropy diagram of curtis and single row rateau turbine. For understanding the gland sealing system first we have to understand why it is required so there are two main reason. Our steam turbine portfolio spans across all fuels, from gas and coal to nuclear applications from 100. A steam turbine is a mechanical device that extracts thermal energy from pressurized steam and transforms it into mechanical work.
Journal bearings are at each end of each rotor to support the weight of the rotor. There are two classical types of turbine stage designs. Dear all, why ip rolling is preferred than hip hp rolling. Mar 09, 2017 rolling means getting the steam turbine to rotate. Steam turbine operating conditions the steam cycle the essential elements of the steam cycle include the boiler or steam generator, turbines, generator and condenser. One is an impulse design in which the rotor turns as a result of the force of steam on the blades. Very high powertoweight ratio, compared to reciprocating engines. Over the last 100 years, ge has manufactured and installed a worldwide fleet of steam turbines. Ger3705 ge steam turbine design philosophy and technology. Our steam turbines equip 41% of the worlds combinedcycle plants, 30% of fossil power plants, and 50% of the worlds nuclear power plants. Power regulation adjusts the operation of the steam turbine load current, i.
Steam turbines startups 1 principles of steam turbines startups. Intermediatepressure turbine an overview sciencedirect. D0 is the main steam flow before the variable condition. Steam turbine governing is the procedure of controlling the flow rate of steam to a steam turbine so as to maintain its speed of rotation as constant. The blade is the component that extracts energy from the steam.
Thermal efficiency of a steam turbine is usually higher than that of a reciprocating engine. In the turbine governor the target rotational speed 3000 rpm is set as well as runup rate. Turbine rolling procedure free download as pdf file. In case of turbines with cooling water preheating and lowpressure lp bypass, prior to supplying steam the regeneration and dumping systems have to be. Since the steam turbine is a rotary heat engine, it is particularly suited to be used to drive an electrical generator. Pdf simulation of speed steam turbine control system. Further, once the turbine has been split into separate sections, additional efficiency gains can be made by reheating the steam when it exits the highpressure turbine where it will have cooled and before it enters the intermediatepressure turbine. Efficiency will depend on turbine size or rotor diameter, blade geometries, speed, extreme condition of steam and other losses. Latest technologies and future prospects for a new steam turbine. How does the steam turbine gland sealing system work.
Appendix b glossary of steam turbine terms antifriction bearing. Hga excess air discharge flue gas temperature main steam condition reheat back pressure lhv. As turbine exhaust is connected to a condenser which is operated below atm pressure so there are chances of air ingres or va. This service generally calls for a backpressure noncondensing steam turbine. The purpose of this pilot valve was to maintain a rolling steam supply to the cruising turbine sufficient to turn it at around 400 r. Schofield ge company schenectady, ny introduction the need to provide stateoftheart products for a diverse and everchanging market is the chal lenge facing steam turbinegenerator manufactur ers in the 90s. All controls of hp bypass are on manual mode and all valves are closed. Schematic diagram of 200 mw unit 8 construction of the steam generator is carried out in two distinct bodies, symmetrical with the axis of the group, operating in parallel to the k2001 steam turbine. An antifriction bearing is a bearing that utilizes rolling elements between the stationary and rotating assemblies. Prior to supplying steam to the turbine, the steam supply pipelines have to be drained and heated up. In noncondensing turbines or backpressure turbines, steam exhausts at a pressure greater than.
Steamturbine principles and practice by croft, terrell, 1880publication date 1923 topics steamturbines publisher new york. Steam consumption of steam turbine is depending to required output power and efficiency of the turbine. Impulse turbines an impulse turbine uses the impact force of the steam jet on the blades to turn the shaft. Steam turbine performance 3 4 2 1 46 45 44 43 42 41 43 42 41 40 39 % % 1. Now charge the turbine inlet valve for line warm up by venting out the steam via turbine start up vent. Steam turbine portfolio overview digital asset management. The water and steam run through a continuous cycl e of water boiled into steam, used in the engine, condensed back to water, and then pumped back into the boiler for reuse, a cycle first studied scientifically by the. In an extracting type turbine, steam is released from variousin an extracting type turbine, steam is released from various stages of the turbine, and used for industrial process needs or sentstages of the turbine, and used for industrial process needs or sent to boiler feed water heater to. The principles of correct conducting startups have been developed over the longterm operation of steam turbines and contain experience of turbine designers, constructors and operators. Regulation of the steam turbine can be achieved by optimal, reliable and safe operation. Steam for turbine is provided by pp330140p55 type steam generator, a oncethrough coalfired boiler 8. A presentation on turbine rolling atrs final 2 electric. The method of claim 1 wherein the prewarming includes filling the steam turbine with the steam.
Principles of operation of a steam turbinewhen high temperature steam passes through a steam turbine. Powerpoint presentation on steam turbine powerpoint. Steam turbine operating conditions, chemistry of condensates. Consider steam turbine drives for rotating equipment steam turbines are well suited as prime movers for driving boiler feedwater pumps, forced or induceddraft fans, blowers, air compressors, and other rotating equipment. Consider steam turbine drives for rotating equipment. One thrust bearing typically is provided for the entire steam turbine to maintain the axial position of the rotor. The drop in pressure across the turbine will cause it to rotate. Two basic types of steam turbine designs are available. The main use for steam turbines is in electricity generation in the 1990s about 90% of the worlds electric production was by use of steam turbines however the recent widespread application of large gas turbine units and typical combined cycle power plants has resulted in reduction of this percentage to the 80% regime for steam turbines.
A presentation on turbine rolling atrs final 2 free download as powerpoint presentation. Method for starting a steam turbine alstom technology ltd. The starting process of a steam turbine can be divided into three phases. Steam process in steam turbine steam entrance to turbine through governor valv e to control steam capacity and therefore to control turbine speed. Steam expands as it passes through the nozzles, where its pressure drops and its. Because the turbine generates rotary motion, it is particularly suited to driving electrical generators about 90% of all electricity generation in the united states 1996 is by use of steam turbines 1 wiser. Aug 19, 20 a condenser installed at the exhaust or low pressure end of the turbine receives and condenses the steam prior to it being pumped back to the boiler. Nevertheless modern steam turbines are very efficient and operate with internal efficiencies within the range of 80 percent to 90 percent depending upon the steam conditions. Scribd is the worlds largest social reading and publishing site. Steam turbine a steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into useful mechanical work.
Gt load 50mw for cold start up conditions gt load 65 mw for warmhot start up st on turning gear minimum 6 hrs one cep in service one cw pump in service st turning gear operation f. Dec 14, 2016 steam turbine journal bearing and its function steam turbines have journal bearings and thrust bearings. Sliding pressure optimization method for steam turbine with. This is a common feature of the steam turbines used in coalfired power plants. The variation in load during the operation of a steam turbine can have a significant impact on its performance.
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