RU2779348C1 - Steam turbine unit of a double-circuit nuclear power plant - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: invention relates to the field of nuclear power engineering including steam turbine units of double-circuit nuclear power plants (NPPs) with a WWER reactor. Steam turbine unit of a double-circuit NPP with a WWER reactor, containing, in the second circulation circuit, a vertical steam generator with an economiser section, a steam turbine, a condenser, a feeder pump, a feed water heater, a reducer, and an electric generator; wherein the entire thermodynamic process of the second-circuit turbine unit is conducted above atmospheric pressure; working steam from the steam generator is compressed by the compressor and supplied into the adjusting valve with supercritical expansion of the working steam and axial supply thereof to the flow part of the turbine, followed by supplying the spent steam to the feed water heater to be cooled and supplied to the condenser; the condensate from the condenser is fed by the feed pump into the inter-tube space of the feed water heater, then therefrom into the economiser of the steam generator, wherein the turbine, the electric generator, and the compressor are kinematically interconnected via the reducer.

EFFECT: possibility of simplifying the heat diagram of an NPP and raising the performance coefficient of a steam turbine unit.

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Description

The invention relates to the field of nuclear energy, including steam turbine plants (STU) of nuclear power plants (NPP) of a double-circuit type with VVER reactors generating working steam in a steam generator with parameters P=3÷8 MPa and t=240-300°C. From the steam generator, usually saturated or slightly superheated working steam enters the turbines, followed by expansion in the turbines to P _k \u003d 3 ÷ 5 kPa and T _k \u003d 297-306 K. For the operation of double-circuit steam turbines, special wet steam turbines are used that operate on wet steam. Under these conditions, turbine blades are exposed to unacceptably strong erosion, so it is necessary to reduce the steam flow rate in the turbine stages, and this leads to a decrease in U / C _f , causing a sharp drop in efficiency. 3.25. [1] and the efficiency of saturated steam turbine plants does not exceed η _oi =33-35%. A diagram of such a nuclear power plant is shown in Fig. 1.29. b [1]. In order to increase the efficiency of power plants of thermal power plants, including nuclear ones, combined-cycle power plants (CCP) are introduced into the thermal circuits of stations, in which the products of fuel combustion pass sequentially through a gas turbine plant (GTP) and a steam generator of a steam turbine unit; or they use a thermal scheme with a high-pressure steam generator of the turbine unit that acts as a gas turbine combustion chamber [2], [3].

Disadvantages of analogues [1], [2], [3].

1. The complexity of the thermal scheme:

[1] - the need to use wet steam turbines, ejectors for air suction from the condenser, ejector coolers, low and high pressure heaters, in regeneration systems, a deaerator; [2], [3] - it is necessary to use the entire complex of the steam turbine unit and the complex of the gas turbine unit to utilize the heat content of the gas turbine exhaust, and this leads to an increase in the range of equipment and operating costs of the entire power plant, which do not affect the efficiency of the energy complex. Here it is necessary to take into account the feasibility study of the entire project [2], [3].

2. Low efficiency values:

[1] Due to the low initial parameters of the working steam, reduced relative internal efficiency η _oi , the efficiency of saturated steam NPP turbine plants is low and in the best of them reaches 33÷35% (net efficiency). Closest to the claimed solution (prototype) is [1].

The disadvantages of the prototype [1].

1. The complexity of the thermal scheme.

2. Low efficiency values.

The purpose of the invention.

Simplification of the thermal circuit of NPP, increase in the efficiency of the steam turbine plant of a double-circuit type NPP. The goal is achieved as follows: a steam turbine plant of a double-circuit type NPP with a VVER reactor, containing in the second circulation circuit a vertical steam generator with an economizer section, a steam turbine, a condenser, a feed pump, a feed water heater, a gearbox, an electric generator, while the entire thermodynamic process of the second circuit turbine plant passes above atmospheric pressure, the working steam from the steam generator is compressed by the compressor and fed into the control valve with supercritical expansion of the working steam and its axial supply to the turbine flow path, with the subsequent supply of the exhaust steam to the feed water heater, where the steam is cooled and fed to the condenser, condensate from the condenser is supplied feed pump into the annular space of the feed water heater, and from it to the economizer of the steam generator, and the turbine, electric generator, compressor are kinematically connected to each other through a gearbox. The simplification of the thermal scheme is achieved by eliminating the condensate pump, ejector cooler, ejector for air suction from the condenser, low pressure heater, external separator, secondary superheater, low pressure steam turbine, condensate regenerative heating system, deaerator, due to the fact that the supercritical expansion pressure taken above atmospheric pressure (P _n =0.15 MPa at t _n =120°C and condensation temperature t _s =111°C). The increase in the efficiency of the steam turbine plant is achieved by increasing the heat drop generated in the turbine from the compression of the steam leaving the steam generator by the compressor to P ₀ =4.5 MPa and t ₀ =385 ° C and subsequent supercritical expansion of the working steam to P _n , t _n , - while it turns out the steam flow rate in the turbine W _p =920 ^m / _s , which allows the use of turbines with η _oi =0.7-0.8.

The proposed device is illustrated in the drawing.

The graphic image consists of one figure Figure

1 "Steam turbine plant of double-circuit type NPP".

The steam turbine plant of a double-circuit type NPP contains in the first circuit a VVER reactor 1, a vertical steam generator with an economizer section 2, a primary circuit pump 3, in the second circuit it contains a steam generator 2, a compressor 4, a turbine 5, a feed water heater 6, a condenser 7, a feed pump 8, electric generator 9, gearbox 10, control valve with supercritical expansion of working steam 11 (control valve) [4].

The device works as follows. Slightly superheated or saturated steam from the steam generator 2 with the parameters P ₁ =3.00 MPa, t ₁ =300°C enters the compressor 4, where it is adiabatically compressed, acquiring the parameters P ₀ =4.5 MPa, t ₀ =385°C. After the compressor 4, the working steam enters the control valve 11, where it expands supercritically to the parameters P _n \u003d 0.15 MPa, t _n \u003d 120 ° C, while accelerating to a speed W _p \u003d 920 ^m / _s , the velocity head is triggered in the turbine 5 on the blades of the turbine 5 (turbine 5 can have one or two speed stages).

After the turbine 5, steam with parameters P _n , t _n enters the feed water heater 6, where it heats the feed water while cooling down to P _k = 0.15 MPa, t _s ≈111 ° C and goes to the condenser 7, where it condenses. The condensate from the condenser 7 is fed by the feed pump 8 first into the annular space of the feed water heater 6, and then into the economizer of the steam generator 2. The turbine 5, the electric generator 9, the compressor 4 are kinematically connected to each other through the gearbox 10 to coordinate their own rotation speeds.

Preliminary calculations show the following: external power of NPP STP N _e =60 MW; thermal efficiency η ^A _ter =0.593; working steam consumption G=40 ^kg / _s ; compressor power N _to =10 MW.

Literature

1. Shcheglyaev A.V. "Steam Turbines". M. "Energoatomizdat", 1993. S. 58-64.

2. RU 2334112 C2 dated January 28, 2005

3. RU 2553725 C1 dated 05.05.2014

4. Ozhigov G.E. "Hydrogasdynamics in science and technology". L., "Shipbuilding", 1970. Pp. 158, 159. Fig. 92.

Claims (1)

A steam turbine plant of a double-circuit type NPP with a VVER reactor, containing in the second circulation circuit a vertical steam generator with an economizer section, a steam turbine, a condenser, a feed pump, a feed water heater, a reducer, an electric generator, characterized in that the entire thermodynamic process of the second circuit turbine plant passes above atmospheric pressure , the working steam from the steam generator is compressed by the compressor and fed into the control valve with supercritical expansion of the working steam and its axial supply to the flow path of the turbine, with the subsequent supply of the exhaust steam to the feed water heater, where the steam is cooled and fed to the condenser, the condensate from the condenser is supplied by the feed pump into the annular space of the feed water heater, and from it into the economizer of the steam generator, wherein the turbine, electric generator, compressor are connected kinematically through a gearbox.

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