RU2391517C2 - Steam-gas installation - Google Patents

Abstract

FIELD: power industry.

SUBSTANCE: steam-gas installation consists of gas-turbine assembly, steam boiler-utiliser with steam generating circuits of two pressures containing economiser and evaporating surfaces of two pressures, super-heater of high pressure steam (h.p.), and steam turbine assembly with condenser and two steam turbines. A steam inlet of the first of steam turbines is communicated with an outlet of the steam super-heater of h.p. The steam outlet of the second steam turbine is communicated with the steam inlet of the condenser. The condensate outlet of the condenser is connected with the condensate inlet of the boiler-utiliser. An intermediary steam super-heater is connected with its steam inlet to the steam outlet of the first steam turbine, while with its steam outlet it is connected with the steam inlet of the second steam turbine. Also the intermediary steam-super-heater is made as a water steam super-heater and is communicated at its steam inlet with the low pressure (l.p.) steam outlet of the boiler-utiliser, and at its heating water inlet and outlet it is correspondingly communicated with water inlet and outlet of the h.p. economiser of the boiler-utiliser.

EFFECT: increased total heat drop obtained in steam turbines due to reduced pressure losses in circuit of intermediary super-heating and due to reduced temperature of steam before intermediary steam super-heater.

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Description

The invention relates to a power system and can be used in binary combined cycle power plants (CCGT) containing gas turbine plants (GTU) with recovery boilers (KU) and steam turbines. The greatest effect can be obtained from the implementation of the invention in binary combined cycle gas turbines with medium-capacity gas turbines, as well as with a relatively low temperature of exhaust gases.

They strive to provide an increase in the efficiency of the steam-power part of high-temperature combined cycle units by increasing the total heat transfer triggered in steam turbines, which is achieved, in particular, by increasing the initial pressure and applying intermediate superheating (superheating) of the steam after its expansion in the steam turbine to medium pressure.

The closest analogue (prototype) of the claimed invention is CCGT [1] (p.25, Fig.5), containing a gas turbine unit (GTU), a steam boiler-utilizer (KU) of two pressures with an intermediate steam superheater and a steam turbine unit with a condenser and two steam turbines, the first of which is a high-pressure steam turbine (ПТВД) at the steam inlet communicated with the output of KU for steam HP, the second steam turbine is the medium-low pressure steam turbine (PTSND) at the steam outlet communicated with the input of the condenser pair reported output by condensate with a condensate inlet KU input, and an intermediate steam superheater (ППП), communicated at the steam input with the output of the high-pressure turbojet engine for steam, at the steam output - with the PTSND input for steam.

The disadvantage of this technical solution is that it is effective only in relation to powerful CCGT with gas turbines with high-temperature exhaust (in the prototype - above 600 ° C). In such combined cycle plants, a sufficiently high initial pressure level (16 MPa in the prototype) and steam temperature in front of the turbines can be used.

In CCGT, made according to this scheme, equipped with a gas turbine of medium power or with a moderate temperature of the gas at the exhaust, an increase in the initial pressure in front of the high-pressure turbine is ineffective due to an excessive decrease in the height of the high-pressure turbine blades and a decrease in the efficiency of its flow part. With a decrease in the initial pressure, the temperature of the vapor behind the high-pressure tube is increasing. In this case, as well as with a decrease in the temperature of the steam behind the intermediate superheater, the increase in the temperature of the steam in it decreases. The pressure losses in the intermediate overheating path are little dependent on temperature and in the above scheme are about 15-20% of the pressure behind the high-pressure turbine engine. They are the sum of the losses in the steam supply lines s.d. from a steam turbine to the substation KU and vice versa, as well as pressure losses in the KU itself: in the unit for distributing steam through the pipes of the heat transfer surface of the substation, in the pipes of the substation itself and in the collector of the overheated intermediate steam (industrial steam) of the KU.

As a result, the use of intermediate steam superheating in such CCGTs is ineffective; the above scheme is also not applied when creating CCGT with a relatively low temperature of gases in front of the CC.

The technical result of the inventive CCGT unit is to increase the total heat difference triggered in steam turbines of a CCGT of medium power by reducing pressure losses in the intermediate superheat path and lowering the temperature of the steam in front of the intermediate steam superheater.

To achieve the specified technical result in the inventive CCGT unit containing a gas turbine, steam boiler with steam generating circuits of two pressures, containing economizing and evaporating surfaces of two pressures and a superheater of high pressure steam, a steam turbine unit with a condenser and two steam turbines, the first of which is connected to the steam inlet with steam superheater output in steam, the second steam turbine in the steam output is connected to the steam input of the condenser communicated at the condensate output with the condensate inlet KU, and the intermediate steam superheater communicated at the steam input with the output of the first steam turbine in steam, at the steam output - with the inlet of the second steam turbine in steam, in accordance with the invention, the intermediate steam superheater is made in the form of a water superheater and communicated at the steam inlet also with the output of the boiler for a couple of s.a., at the inlet and outlet of heating water, respectively, with the output and at Odom economizer E KU on water.

The invention is illustrated by an example of its implementation, schematically depicted in the drawing.

The CCGT shown in the drawing contains GTU 1 with a turbogenerator 2, steam KU 3 with two-pressure steam circuits containing an economizer of low pressure (n.d.) 4, an evaporator n.d. 5 with a drum separator n.d. 6, economizer high pressure (r.d.) 7, evaporator r.d. 8 and r.h. steam superheater 9, a steam turbine installation with a condenser 10 and two steam turbines 11 and 12, the first of which is an east steam turbine (PTVD) 11 - at the steam input it is communicated with the output of the steam superheater 9 in pairs, the second steam turbine is a steam turbine n.d. (ПТНД) 12 - at the steam output it is communicated with the steam input of the capacitor 10, communicated at the condensate output through the condensate pump 13 with the condensate pump 3 input, and an intermediate steam superheater (ППП) 14, communicated at the steam input with the first output steam turbine ПТВД 11 in pairs, at the outlet in pairs - with the input of the ПТНД 12 in pairs. Economizer E 7 at the entrance of the water communicated with the output of the economizer n.d. 4 by water through a feed pump 15. PPP 14 is made in the form of a water superheater and communicated at the steam inlet also with the output of the KU (in this example, the drum-separator n.d.6) for a couple of n.d. exit and entry economizer east 7 by water. In this example, the SPP 14 at the water outlet is communicated with the input of the economizer east. 7 through the feed pump fifteen.

In the above example, the CCGT unit also contains a water heater of steam n.d. (VPND) 16, while PPP 14 is communicated at the inlet in pairs with the output of the KU (in this case, the drum-separator n.d. 6) for a couple of n.d. through the VPND 16 path in pairs, at the outlet of heating water with the entrance of the economizer of the east KU for water - through the VPND 16 path for heating water and - in this example - through the HP feed pump fifteen.

The purpose of VPND 16 is to preheat saturated steam n.d. in front of BCP 14 by approximately 2–3 degrees to avoid condensation in the steam line between drum n.a. 6 and IFR 14.

CCP works as follows.

GTU 1 does the work of driving a turbogenerator 2. In KU 3, the heat of the exhaust gases of GTU 1 produces a pair of two pressures. Vp fed from the superheater steam 9 in the high-pressure turbine engine 11, where it expands to a pressure in the n.d. circuit, performing work on the drive of the turbogenerator 2. Next, the spent steam of the high-pressure tube 11 together with the steam coming from the n.d. circuit KU 3 (in this example, from VNPD 16), are fed to the input of PPP 14 in pairs, where it is overheated with water of the air supply supplied from the economizer of the air supply 7. From the SPP 14, the superheated steam enters the ПТНД 12, where the steam expands to the pressure in the condenser 10, while doing the job of driving the turbogenerator 2.

Since the steam in the high-pressure tube 11 expands to a pressure in the n.a. circuit, the steam temperature during expansion in the high-pressure tube 11 decreases approximately to the level of the saturation temperature, i.e. to a much lower level than in the prototype and than the temperature of the water behind the economizer vd. Thanks to this, water vd is used as a heating coolant in PPP 14, while the heat consumption for intermediate superheating of steam is produced by reducing the steam production of the HP circuit, and not the productivity of the HP circuit, as in the prototype.

Since PPP 14 is a water superheater, it is not steam that flows in its pipes, but heating water. The pressure loss in the path of the intermediate overheating of the claimed CCGT unit is mainly the loss of steam pressure in the body of the water SPP 14 during transverse steam flow around water pipes, and with a significantly higher heat transfer coefficient than in the prototype. As a result, the water SPP 14 turns out to be much more compact than the gas KPP KU of the prototype and can be placed near the high-pressure air flow 11 and high-pressure heat-transfer device 12 or directly in the transitional section between the high-pressure air heaters and high-pressure heat transfer pipes in pairs (i.e., pressure losses in the steam supply lines from the steam turbines in the IFR and vice versa are also insignificant or absent). The industrial steam collector and the industrial steam distribution unit for the PPP pipes are absent. As a result, the total pressure loss in the overheating path is approximately an order of magnitude smaller than in the prototype.

As a result, the efficiency of intermediate overheating under CCGT conditions with a gas turbine with medium power or with a relatively low temperature of gases in front of a gas compressor increases, and the total heat drop triggered by the high-pressure heat pump and high pressure heat pump increases.

As a result, the claimed device provides an increase in the efficiency of the steam power part of the CCGT unit when used in a CCGT unit with a gas turbine of the indicated type.

The example shown in the drawing is intended only to illustrate the invention in accordance with the formula and do not exhaust the entire variety of possible technical solutions for the implementation of the claimed invention.

In particular, VPND 16 may be absent, and KU may contain a gas steam heater n.d .; east heating water circuit for PPP 14, it can be equipped with a circulation pump, and heating water from VPND 16 (or in the absence of the latter from PPP 14) can be supplied to the economizer. 7 not through the feed pump 15, but by the circulation pump directly to the input of the economizer 7 on water; water PPP 14 due to its small dimensions can be made not remote, as shown in the drawing, but, as mentioned above, built into the transition section between the ATV 11 and the ATU 12 in pairs; the rotor PTVD 11 can be performed not mounted on the same shaft with the rotor PTND 12, but connected to it through a gearbox (as in the prototype); a steam turbine can be mounted on a shaft not of a turbogenerator 2 common with GTU 1, but of a separate turbogenerator; As part of one combined cycle gas turbine per steam turbine, there may be not one, but two or more gas turbines with gas turbines, etc.

Information sources

1. Texas GT24: High Availability and Flexibility / E. Jeffs // Turbomachinery, January / February 2003. p.23.

Claims (1)

Combined cycle gas turbine unit (CCGT) containing a gas turbine unit (GTU), a steam recovery boiler (KU) with steam generating circuits of two pressures, containing economizing and evaporating surfaces of two pressures and a superheater of high pressure steam (HP), a steam turbine unit with a condenser and two steam turbines, the first of which is coupled at the steam inlet to the outlet of the steam superheater. in steam, the second steam turbine in the steam output is connected to the steam input of the condenser communicated at the condensate output with the condensate inlet KU, and the intermediate steam superheater communicated at the steam input with the output of the first steam turbine in steam, at the steam output - with the inlet of the second steam turbine in steam, characterized in that the intermediate steam superheater is made in the form of a water superheater and communicated at the steam inlet also with the output of the boiler for low pressure steam (n.d.), at the inlet and outlet of heating water - respectively with progress and input economizer E KU on water.

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