RU2755238C1 - Steam turbine power plant with supercritical expansion of working steam - Google Patents

Abstract

FIELD: ship power engineering.

SUBSTANCE: invention relates to the field of ship power engineering and relates to the design of a ship's power plant with electric propulsion and a steam turbine power plant (STPP). Steam turbine plant with supercritical expansion of working steam, containing a steam boiler with an economizer, a steam turbine, a condenser, a feed pump, a steam regenerative air heater, an electric generator, while the steam turbine is made in the form of a single-row speed stage without a guide vane with axial steam supply to the channels of the rotor blades from a control valve in the form of a Laval nozzle with a variable throat section, and the expanding part of the nozzle is formed by the annular cross-section of two identical circular cones with axial displacement relative to each other so that the outer cone mates with the outer diameter of the turbine blades and with the valve seat, and the inner cone rests on the diameter at the base of the turbine blades, while the flow path of the turbine is docked to the flow path of the duct air heater, the steam from which is fed to the condenser, and the condensate from the condenser is fed by the feed pump to the boiler economizer, and the air into the air heater is fed tangentially into the annular space and tangentially removed from it into the boiler furnace volume.

EFFECT: invention allows simplifying the design, control and regulation, increasing efficiency of the STPP.

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Description

The invention relates to the field of marine power engineering and relates to the design of a ship's power plant with electric propulsion and a steam turbine power plant (PTU).

Known PTU transport vessel [1] Fig. 5.5, containing a steam boiler, a turbo-gear unit (TZA), a condenser, a condensate pump, an ejector cooler, a low pressure heater, a deaerator, a feed pump, a high pressure heater.

The steam pressure in the last stages of the high pressure fuel pump and in the condenser, as a rule, is below atmospheric (pressure in the condenser P _k = 0.005 MPa).

Known "Active steam turbine of supercritical parameters" [2], containing three stages of pressure, separated by fixed diaphragms with mounted in them Laval nozzles evenly spaced around the circumference opposite the blades of active working grids (turbine impellers).

Disadvantages of analogs [1], [2].

1. The complexity of the design:

[1] the need to use TZA with multistage turbines, a condensate pump, an ejector cooler, an ejector for suction of air from a condenser, a low and high pressure heater, a deaerator;

[2] the need for a three-stage turbine, numerous composite (consisting of several parts) Laval nozzles, supercritical parameters of the working steam (P ₀ = 23.5 MPa, t ₀ = 540 ° C - according to the prototype).

2. Low efficiency:

[1] modern PTU transport vessels with the corresponding parameters of the working steam have an efficiency η _e = 0.24-0.34, [1] p. 157, [3] p. 493; [2] Numerous composite Laval nozzles will also cause numerous steam losses through leaks, in the nozzle itself, which consists of several parts, and on the mating end surfaces of the diaphragms and impellers, and on the outer diameters of the impellers.

3. The complexity of the control and regulation of the STU:

[1] the need to have multiple nozzle valves for supplying steam to the corresponding turbine nozzle group;

[2] the design does not provide for the control and regulation of the turbine. In this case, it remains for [2] only throttle regulation through the steam inlet into the turbine, while the pressure and steam flow rate decrease, which will lead to a decrease in the turbine efficiency due to a drop in pressure and outflow rates from the Laval nozzles. The prototype of the claimed device is [1].

Disadvantages of the prototype [1].

1. The complexity of the design.

2. Low efficiency.

3. The complexity of the management and regulation of vocational schools.

The purpose of the invention.

Simplification of the design, control and regulation, increasing the efficiency of PTU.

The goal is achieved as follows:

a steam turbine plant containing a steam boiler with an economizer, a steam turbine, a condenser, a feed pump, a steam regenerative air heater, an electric generator, while the steam turbine is made in the form of a single-row speed stage without a guide vane with axial steam supply to the channels of the rotor blades from a control valve in the form Laval nozzles with a variable throat section, and the expanding part of the nozzle is formed by the annular section of two identical circular cones with axial displacement relative to each other, so that the outer cone mates with the outer diameter of the turbine blades and with the valve seat, and the inner cone rests on the diameter at the base of the blades turbine, while the flow path of the turbine is docked to the flow path of the duct air heater, the steam from which is fed to the condenser, and the condensate from the condenser is fed by the feed pump to the boiler economizer, and the air into the air heater is fed tangentially into the shell space and is tangentially removed from it into the boiler furnace volume.

Simplification of the design in comparison with [1] and [2] is achieved by eliminating TZA with multistage turbines, a condensate pump, an ejector cooler, an ejector for suction of air from a condenser, a low and high pressure heater, a deaerator due to the fact that the expansion pressure in the turbine is higher atmospheric (0.14 MPa at a condensation temperature t _s = 109 ° C).

At the same time, the control and regulation system is simplified due to the use of a control valve in the form of a Laval nozzle with a variable throat section in the entire range of operating loads (steam consumption) of the turbine.

An increase in the efficiency of the STU is achieved at moderate parameters of the working steam (P ₀ = 3 MPa and t ₀ = 430 ° C) due to the fact that the flow path of the turbine is docked (is a continuation) of the flow path of the duct air heater and when the turbine load drops with a constant expanding part of the nozzle Laval at the outlet of the turbine will automatically increase the pressure and the condensation temperature rises (without any regeneration) this is a feature of the operation of Laval nozzles at different backpressures behind the nozzle [1], [4], [5]. Each load mode will have a specific condensing pressure and temperature.

The proposed device is illustrated by a drawing. The graphic image consists of one figure - Figure 1 "Steam turbine plant with supercritical expansion of working steam". Figure 1 depicts a fragment of a steam turbine plant, including a control valve with a turbine and a ducted air heater, as well as speed triangles of a single-row speed stage. The steam turbine plant contains a steam boiler with an economizer (not shown in the drawing), a steam turbine 1, a condenser, a feed pump (not shown in the drawing), a steam regenerative air heater 2, an electric generator 3, a control valve 4 consisting of a valve seat 5 and a valve plate 6 , having the possibility of axial movement by means of pins 7 with a decrease in the gap between the valve plate 6 and the valve seat 5 forming a variable cross-section of the throat of the Laval nozzle. The valve seat 5 is placed in the steam box 8, into which the working steam is supplied from the quick-closing valve (BZK). The turbine 1 is connected to the electric generator 3 by the shaft 9. The expanding part of the Laval nozzle 10.

The device works as follows.

Superheated steam from the boiler with parameters P ₀ = 3 MPa and t ₀ = 430 ° C through the BZK enters the steam box 8, and from it into the control valve 4 where it acquires a critical speed W _cr = 558 m / s at P _cr = 1, 64 MPa υ _cr = 0.166 m ³ / kg. Moving along the expanding part of the nozzle 10 formed by the annular section of two identical circular cones, the steam accelerates to the axial speed С ₁ = 950 m / s and at this speed enters the rotor blades of the turbine 1, triggering the axial speed in the turbine 1 to С ₂ = 200 m / s having the parameters P ₁ = 0.14 MPa and t ₁ = 180 ° C.

The expansion in the Laval nozzle from P ₀ to P _{1 is} adiabatic. After turbine 1, steam enters the duct air heater 2, where it is cooled to the condensation temperature at P ₁ = 0.14 MPa, t _s = 109 ° C and condenses in the condenser. Condensate from the condenser is pumped by a feed pump to the boiler economizer, and air from the duct air heater 2 is supplied at a temperature of 160 ° C to the boiler furnace volume. The turbine partiality is 1 e = 1, the turbine 1 has no guiding device in order to eliminate the formation of pressure surges at the inlet to the turbine 1, while the average diameter of the turbine 1 d _cp = 1.0 m, and the number of revolutions n = 100 rpm. Tangential air supply and its release from the air heater 2 is due to the desire to obtain a transverse flushing of the tube bundle in order to increase the heat transfer coefficient. Preliminary calculations show the following: the capacity of the STU is 60 MW; thermal efficiency of STU η _t = 0.74; steam consumption G = 30 kr / s.

Literature.

1.L.I. Slobodyanyuk, V.I. Polyakov "Ship steam and gas turbines and their operation", L .: "Shipbuilding", 1983 Pp. 95, 96.

2. RU 2676904 dated December 14, 2017

3. G.N. Alekseev, "General heat engineering" M. "Higher school", 1980 Pp. 493.

4. A. N. Smolenskiy, "Steam and Gas Turbines", M .: "Mechanical Engineering", 1977 Pp. 42-44.

5. G.E. Ozhigov, "Hydro-gas dynamics" in science and technology "," Shipbuilding ", 1970 Pp. 113, 158.

Claims (1)

Steam turbine plant with supercritical expansion of working steam, containing a steam boiler with an economizer, a steam turbine, a condenser, a feed pump, a steam regenerative air heater, an electric generator, characterized in that the steam turbine is made in the form of a single-row speed stage without a guide vane with axial steam supply to the channels rotor blades from a control valve in the form of a Laval nozzle with a variable throat section, and the expanding part of the nozzle is formed by the annular section of two identical circular cones with axial displacement relative to each other, so that the outer cone mates with the outer diameter of the turbine blades and the valve seat, and the inner the cone rests on the diameter at the base of the turbine blades, while the turbine flow path is docked to the flow path of the duct air heater, steam from which is supplied to the condenser, and condensate from the condenser is fed by the feed pump to the boiler economizer, and the air to the air supply The heater is fed tangentially into the shell space and tangentially removed from it into the boiler furnace volume.

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