Calculation of K-200-130 condensing turbine cylinder

Contents

Contents

Task

Description of turbine design K-200-

Thermal calculation of condensing steam turbine

3.1. Preliminary determination of steam costs

3.2. Preliminary construction of expansion process in turbine in i-s diagram

3.3. Calculates the thermal scheme. Determining the Calculated Steam Flow

3.4. Determination of the number of stages of the high pressure cylinder

3.5. Detailed calculation of stages of high pressure cylinder

List of used literature

Application:

Rice. 1. Turbine expansion processes in i-s diagrams

Rice. 2. Longitudinal section of turbine (high pressure cylinder)

(1 A1 sheet)

Rice. 3. Turbine rotor (1 A2 sheet)

Rice. 4. Thermal diagram of K-200-130 turbine unit (1 sheet of A1 format)

2. Description of turbine design K-200-130

The 250 MW 3000 rpm K200130 turbine is a single-shaft unit. The turbine is designed for the pressure and temperature of fresh steam of 200 bar and 560 ° C and the absolute pressure in the condenser of 0.04 bar. Intermediate steam overheating is performed up to 560 ° С. The turbine operates in a unit with a steam boiler unit with a capacity of 640 t/h.

Three-hull turbine with bifurcated steam flow to LPC and steam part branches through upper tiers of penultimate Bauman stages directly to condensers.

Fresh steam is supplied through two automatic shutter valves located in the front part of the HPC. From these valves, steam flows through four pipes to four control valves located on the HPC of the welded structure. Nozzle unit of the first stage consists of four segments and is located in nozzle boxes.

HPC flow part consists of control stage and eleven pressure stages. Diaphragms are installed in three holders. The HPC rotor is all-forged, made of R2 steel and has a critical number of revolutions of 1750 per minute.

End seals of HPC - no-bushing type: ring grooves are turned out at the ends of the shaft, and sealing segments are installed in cages and are retained by flat springs.

Steam with a pressure of 24.5 bar and a temperature of 340 ° C from the HPC is sent to the intermediate boiler superheater. Superheated steam with a pressure of 20.8 bar and a temperature of 565 ° C through two safety valves through four pipes goes to the control valves of the DSC.

Eleven pressure stages are located in the DSC. Diaphragms of the first three stages are installed in the recesses of the housing, and diaphragms of the next eight stages are fixed in two cages. The DSC rotor is combined: the first seven discs are turned out of one forging with the shaft, and the last four discs are put on the shaft in a hot state. Critical number of revolutions of the rotor 1780 per minute. Front end seal without bushing; shaft seal on the side of outlet branch pipe - bushing.

Steam with a pressure of 1.6 bar and a temperature of 235 ° C from the DSC through bypass pipes with a diameter of 1500 mm is supplied to the central part of the LPC and branched into two flows. In each stream there are four stages. Exhaust steam from turbine outlet branch pipes is directed to two condensers welded to outlet branch pipes.

The case of CND consists of their three detachable parts: a middle part cast, from SCh2140 brand cast iron, and final branch pipes welded. Eight discs of the low pressure rotor are put on the shaft in a hot state, which provides the necessary tension at the operating number of revolutions. Disks are secured on shaft by means of radial keys. Critical speed of rotor 1610 per minute. End seals of bushing type. Bushings are fitted on shaft in hot state.

High, medium and low pressure rotors lie on five support bearings: low pressure rotor - on two, and high and medium pressure rotors - on three. High and medium pressure rotors are connected by rigid coupling. Steam is supplied to HPC and DSC from the side of the middle combined bearing. This arrangement made it possible to reduce the length of the unit by 1.5 m and unload the thrust bearing from axial force. This is especially important in the presence of increased reaction on the rotor blades.

HPC and LPC rotors, as well as LPC and generator rotors are connected by semi-flexible couplings.

For rotation of rotors at turbine heating before and after its stop there is a turning gear mounted on the housing of LPC rear bearing.

The average diameter of the last stage is 2100 mm with a working blade height of 765 mm. The ratio d/l = 2.75 and the circumferential velocity at the average diameter u = 330 m/s. The largest diameter along the apex of the working blades of the last stage from the steam outlet side is 2870 mm, and the maximum circumferential speed on the apex of the blade umax = 450 m/s. Weight of low pressure turbine rotor in assembled form is 36 t.

The useful capacity for turbine cylinders is: on the HPC shaft 62 MW, on the HPC shaft 91 MW and on the HPC shaft 51 MW.

The main parts of the turbine operating in high temperature zones are made of alloyed pearlite grade steels. The case of high pressure, nozzle and steam boxes, cases of valves and the case of average pressure to the vertical socket are manufactured of heat resisting hromomolibdenovanadiyevy steel of brand 15H1M1F. Turbine rotors are made of P2 steel. All nozzle discs are made of 34KHN3M steel. The use of pearlite class steels for the manufacture of the turbine allowed to significantly reduce its cost.

The control circuit of the K200130 turbine, in contrast to the control circuits of turbines without intermediate steam overheating, includes additional protection of the turbine from increasing the number of steam revolutions from intermediate steam lines. Four control valves are installed on the DSC, which are controlled by the same servomotor as the HPC control valves. In addition, two safety valves are installed on the intermediate superheating steam pipelines upstream of the DSC, switching steam to the condenser in case of complete load shedding. These valves operate in the same way as automatic stop valves for fresh steam.

To supply the turbine with oil, a centrifugal type oil pump with a capacity of 7000 l/min is provided. It is installed in housing of front bearing, and its rotor is connected by coupling to turbine rotor. The oil is supplied to the control at a pressure of 19.6 bar, the oil is supplied to the bearings from a twin injector installed in the turbine oil tank. There is no gear reducer and reduction valve in the oil supply system, which increases the reliability of its operation.

Start-up centrifugal oil electric pump is provided for turbine start-up and shutdown. When the oil pressure on the bearing lubrication drops below 0.45 bar, the emergency electric pump operating from the AC mains is automatically activated. In case of de-energizing of auxiliary feeders, a standby oil pump with a DC electric motor is installed at the station, which is fed from the battery and automatically actuated when the oil pressure drops to 0.45 bar on bearings.

Турбина1.cdw

K-200-130.cdw