50MW supercritical CO2 axial flow turbine heat insulation structure

Abstract

The invention discloses a heat insulation structure of a 50MW supercritical CO2 axial flow turbine. In a high-parameter CO2 working medium environment, a shrinkage fit ring inner cylinder has the condition of balanced air blowing and leakage, and due to the fact that the air leakage parameter is high, dry gas sealing is difficult to cool to the working temperature when an outer cylinder end cover is in direct contact after leakage. The cylinder comprises an inner cylinder and an outer cylinder, the two sides of the outer cylinder are connected with end covers through bolts respectively, and the cylinder is characterized in that two stepped ring grooves are formed in the end covers, the first stepped ring groove of each end cover is fixedly connected with a cover plate through a vertical bolt, the cover plate and the second stepped ring groove of each end cover form a cooling cavity, and the cooling cavity is communicated with the cooling cavity. An isolation notch is formed in the dry gas sealing position of the end cover, two cooling gas inlets are formed in the end cover, one cooling gas inlet is communicated to the cooling cavity, and the other cooling gas inlet is communicated to the isolation notch. The method is applied to heat insulation of the 50MW supercritical CO2 axial flow turbine.

Description

Technical Field

[0001] The invention relates to a 50MW supercritical CO2 axial flow turbine heat insulation structure. Background Art

[0002] As the world's energy landscape develops towards high efficiency, cleanliness and low carbon, countries around the world have formulated energy transformation strategies. Supercritical carbon dioxide (SCO2) cycle power generation technology has been widely recognized for its high efficiency, low cost, high cleanliness and compact structure, and has good application prospects in various power generation fields. At present, domestic supercritical CO2 turbine power generation technology is in the experimental stage, and high-power units have not yet been commercially operated. It is currently in the window period for decision-making and layout. The newly developed supercritical CO2 axial flow turbine is conducive to improving market competitiveness and adapting to the needs of national energy policies under the background of "dual carbon".

[0003] In a high-parameter CO2 working fluid environment, the red sleeve inner cylinder will experience balance drum leakage. Due to the high leakage parameters, direct contact with the outer cylinder end cover after leakage will make it difficult for the dry gas seal to cool to the operating temperature (maximum 250°C). The end cover bolts will also relax quickly at high temperatures and the seal will also leak. Summary of the invention

[0004] The object of the present invention is to solve the above-mentioned problems and thereby provide a 50MW supercritical CO2 axial flow turbine insulation structure.

[0005] The above purpose is achieved through the following technical solutions: A 50MW supercritical CO2 axial flow turbine insulation structure, which comprises: an inner cylinder and an outer cylinder, the two sides of the outer cylinder are respectively connected to the end cover by bolts, two stepped annular grooves are opened inside the end cover, the first stepped annular groove of the end cover is connected and fixed with a cover plate by vertical bolts, the cover plate and the second stepped annular groove of the end cover form a cooling chamber, the dry gas seal of the end cover is provided with an isolation notch, and two cooling air inlets are opened on the end cover, one of which is connected to the cooling chamber, and the other is connected to the isolation notch.

[0006] The 50MW supercritical CO2 axial flow turbine insulation structure is characterized in that the cover plate is a stepped plate with a circular hole in the middle, and the step of the cover plate is embedded in the second stepped annular groove of the end cover.

[0007] In the 50MW supercritical CO2 axial flow turbine insulation structure, the inner diameter of the circular hole in the center of the cover plate is greater than or equal to the inner diameter of the end cover.

[0008] The 50MW supercritical CO2 axial flow turbine heat insulation structure has cooling air passing through the cooling air inlet. Beneficial Effects

[0009] 1. The present invention adds a cover plate to the end cover and forms a cooling chamber with the cover plate at the second stepped annular groove of the end cover, and cooling gas is introduced into the cooling chamber. The first channel is dry gas sealing gas to prevent CO2 gas leakage. The isolation notch is used to isolate the cooling gas to prevent the dry gas seal from overheating. A part of the cooling gas and the cooling channel flow out through the gap between the rotor and the cover plate to balance the blower leakage gas convection, and a part of the cooling gas and the first channel gas are led out through the third channel, which effectively reduces the temperature of the end cover, the temperature of the bolts and the temperature of the dry gas seal, and plays a good protective role. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 This is a state diagram where the balance hub leaks causing the center temperature of the end cover to be higher; Figure 3 This is the end cover sealing effect diagram; Figure 4 It is the temperature distribution diagram of the outer cylinder and the end cover after adding the cover plate and introducing the cooling air; Figure 5 It is to add the cooling air rear end cover flange sealing status diagram; In the figure: 1. first channel; 2. isolation notch; 3. third channel; 4. cooling chamber; 5. first step annular groove; 6. second step annular groove; 7. end cover; 8. cover plate; 9. isolation notch; 10. balance drum. DETAILED DESCRIPTION

[0011] Reference Figure 1 A 50MW supercritical CO2 axial flow turbine insulation structure, which comprises: an inner cylinder and an outer cylinder, the two sides of the outer cylinder are respectively connected to the end cover 7 by bolts, two step ring grooves are opened inside the end cover, and the first step ring groove 5 of the end cover is connected and fixed with the cover plate 8 by vertical bolts, and the cover plate and the second step ring groove 6 of the end cover form a cooling chamber 4, and the dry gas seal of the end cover is provided with an isolation notch 2, and two cooling air inlets are opened on the end cover, one of which is connected to the cooling chamber, and the other is a second channel 2, and the second channel is connected to the isolation notch.

[0012] The 50MW supercritical CO2 axial flow turbine insulation structure is characterized in that the cover plate is a stepped plate with a circular hole in the middle, and the step of the cover plate is embedded in the second stepped annular groove of the end cover.

[0013] In the 50MW supercritical CO2 axial flow turbine insulation structure, the inner diameter of the circular hole in the center of the cover plate is greater than or equal to the inner diameter of the end cover.

[0014] The 50MW supercritical CO2 axial flow turbine heat insulation structure has cooling air passing through the cooling air inlet.

[0015] When cooling gas protection is not added, the balance drum leaks and causes the local temperature of the inner circle area of ​​the intake side end cover (where it cooperates with the dry gas sealing structure) to reach 587°C. The dry gas sealing structure (with a maximum operating temperature of 250°C) will not be able to ensure the sealing function. Figure 2 As shown; After the turbine has been running for 10,000 hours, the tightening force of the rear cover sealing bolts will continue to decrease, and the exhaust will leak through the bolt holes. Figure 3 As shown; A cover plate is added to the end cover, and a cooling chamber is formed with the cover plate at the second step ring groove of the end cover, and cooling gas is introduced into the cooling chamber. The first channel 1 is dry gas sealing gas to prevent CO2 gas leakage. The isolation groove is used to isolate the cooling gas to prevent the dry gas seal from overheating. A part of the cooling gas in the isolation groove flows out through the gap between the rotor and the cover plate together with the cooling gas in the cooling channel to counterflow with the leakage of the balance drum 10, and a part of the cooling gas is led out through the third channel together with the gas from the first channel 1, which effectively reduces the temperature of the end cover, the temperature of the bolts and the temperature of the dry gas seal, and plays a good protective role.

[0016] Reference Figure 4-Figure 5 The cover plate is used for heat insulation and cooling air is introduced into the cooling chamber formed by the cover plate and the end cover to ensure that the temperature of the dry gas sealing area is below 250°C, reduce the working temperature of the end cover bolts, ensure the bolt tightening force and the end cover sealing is good.

Claims

1. A 50MW supercritical CO2 axial flow turbine insulation structure, comprising: An inner cylinder and an outer cylinder, the two sides of the outer cylinder are respectively connected to the end cover by bolts, and the characteristics are: two stepped annular grooves are opened inside the end cover, and the vertical bolts are used to connect and fix the cover plate at the first stepped annular groove of the end cover, and the cover plate and the second stepped annular groove of the end cover form a cooling chamber, and an isolation groove is opened at the dry gas seal of the end cover, and two cooling air inlets are opened on the end cover, one of which is connected to the cooling chamber, and the other is connected to the isolation groove.

2. A 50MW supercritical CO2 axial flow turbine insulation structure according to claim 1, characterized in that: The cover plate is a stepped plate with a circular hole in the middle, and the step of the cover plate is embedded in the second stepped annular groove of the end cover.

3. A 50MW supercritical CO2 axial flow turbine insulation structure according to claim 2, characterized in that: The inner diameter of the circular hole in the center of the cover plate is greater than or equal to the inner diameter of the end cover.

4. A 50MW supercritical CO2 axial flow turbine insulation structure according to claim 3, characterized in that: The cooling air passage is filled with cooling air.

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