High efficient and durable blast furnace gas trt expander

Abstract

The utility model discloses a high -efficient durable blast furnace gas TRT expander. The overall cascade of existing blast furnace gas expander is relatively lower in flow efficiency. The utility model adopts three -level flow design, including one -level adjustable static blade, one -level movable blade turbine disc, two -level adjustable static blade, two -level movable blade turbine disc, three -level adjustable static blade and three -level movable blade turbine disc, one -level adjustable static blade, two -level adjustable static blade and three -level adjustable static blade adopt rear -loading type static blade, and static blade airfoil profile is wing type, one -level movable blade turbine disc, two -level movable blade turbine disc and three -level movable blade turbine disc all adopt semi -impulse type and narrow chord development leaf shape. The utility model improves the isentropic expansion efficiency of unit.

Description

Technical Field

[0001] This utility model belongs to the field of expander technology, specifically relating to a high-efficiency and durable blast furnace gas TRT expander. Background Technology

[0002] The current TRT (Transformer Toll Collection) main unit for blast furnace gas expanders employs a two-stage flow design consisting of stationary blades, moving blades, and a support cylinder. Blast furnace gas flows through the first-stage stationary blades, where most of its pressure energy is converted into velocity energy, before entering the first-stage moving blades to perform work. After the enthalpy energy decreases, the gas re-enters the second-stage stationary blades to adjust the airflow angle of attack, adapting to the angle of attack of the second-stage moving blades, and then continues to perform work. Due to the small size of blast furnaces and the limited gas volume, many models have relatively small root diameters for the flow blades (630–760 mm). This smaller root diameter in the two-stage flow design results in a smaller W2 (outlet relative velocity) in the moving blade velocity triangle, a relatively smaller moving blade velocity coefficient φ, and a relatively lower overall flow efficiency of the blade cascade.

[0003] Since the working medium of the TRT is blast furnace gas, the flow rate of which varies greatly during operation, generally ranging from 50% to 120% of the design point. Therefore, the stationary blades are adjustable. The adjustable stationary blades are of a front-loaded type. While their advantage is wear resistance, this blade shape easily causes secondary flow losses at the blade root and tip during small flow rate adjustments, resulting in significant secondary flow losses. Furthermore, the use of a wide-chord blade profile leads to a severe imbalance in the blade height-to-width ratio; the blade reaction degree is large, reaching 75%, further increasing secondary flow separation at the first-stage blade root section; the wide-chord blade profile also results in a large inter-stage spacing, preventing the full utilization of the tail velocity and causing energy losses. Therefore, the original flow path design suffers from low isentropic expansion efficiency, typically between 70-72% for small units and between 78-82% for large units. Utility Model Content

[0004] To overcome the shortcomings of existing technologies, this utility model provides a high-efficiency and durable blast furnace gas TRT expander, which improves the isentropic expansion efficiency of the unit.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows: The high-efficiency and durable blast furnace gas TRT expander is as follows: It adopts a three-stage flow design, including a first-stage adjustable stationary blade, a first-stage moving blade turbine disk, a second-stage adjustable stationary blade, a second-stage moving blade turbine disk, a third-stage adjustable stationary blade, and a third-stage moving blade turbine disk; The first-stage adjustable stator blade, the second-stage adjustable stator blade, and the third-stage adjustable stator blade are rear-loaded stator blades, and the stator blade profile is airfoil-shaped. The first-stage, second-stage, and third-stage turbine disks all adopt a semi-impact type and narrow chord spreader shape.

[0006] Furthermore, the first-stage adjustable stationary blade, the second-stage adjustable stationary blade, and the third-stage adjustable stationary blade adopt a chord length to blade height ratio of H=1.5C-1.65C, where H is the height and C is the chord length; the maximum thickness D of the curved surface of the blade back is located at 0.33-0.35 of the total chord length of the blade; the maximum thickness D is 0.27 of the chord length at the blade tip and 0.20 of the chord length at the blade root near the rotor.

[0007] Furthermore, the inlet α angle of the profile at the HUB of the first-stage, second-stage, and third-stage moving blade turbine disks is 65-75°, and the outlet β angle is 30° to 45°; the ratio of the maximum thickness D of the moving blade to the chord span C is D / C=0.25.

[0008] Furthermore, the blade tips on the first-stage, second-stage, and third-stage moving blade turbine disks are designed with conical inclined surfaces, and the blade tip inclination angle is 17° to 30°.

[0009] Furthermore, a first-stage moving blade tip seal, a second-stage moving blade tip seal, and a third-stage moving blade tip seal are respectively provided at the moving blade positions on the first-stage moving blade turbine disk, the second-stage moving blade turbine disk, and the third-stage moving blade turbine disk; The first-stage moving blade tip seal, the second-stage moving blade tip seal, and the third-stage moving blade tip seal have the same structure, including a sealing support body and a carbon fiber ring body. The sealing support body is fixed on the stationary blade support cylinder and is used to clamp and fix the carbon fiber ring body. The carbon fiber ring body is shaped like a fingertip, and the sealing contact surface with the moving blade adopts the same conical inclined surface design as the moving blade tip, with an inclination angle of 17° to 30°.

[0010] Furthermore, the first-stage moving blade turbine disk, the second-stage moving blade turbine disk, and the third-stage moving blade turbine disk adopt an integral turbine disk design.

[0011] The beneficial effects of this utility model are: 1) This utility model adopts a three-stage flow design without changing the original unit casing, which improves the isentropic expansion efficiency of the unit; 2) The stationary blade of this utility model adopts a post-loaded blade shape modification. The blade life is not reduced, but the secondary flow loss is improved. The moving blade adopts a semi-impact blade shape and a narrow chord blade shape design. The processing technology adopts an integral milling turbine disk process, which improves the secondary flow loss of the suction surface of the wide chord blade shape and improves the isentropic expansion efficiency of the flow. 3) The first two stages of the three-stage turbine in this utility model are made of bidirectional precipitation hardening stainless steel, and the third stage turbine is made of titanium alloy, which has strong resistance to low-temperature corrosion. 4) This utility model adopts carbon fiber soft contact "finger tip seal" and large inclined blade tip of moving blade, which reduces leakage loss at the blade tip of moving blade. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is a three-stage flow diagram of the present invention; Figure 3 This is a line drawing of the adjustable stationary blade profile of this utility model; Figure 4 This is a schematic diagram of the post-loaded stationary blade structure of this utility model; Figure 5 This is a diagram of the moving blade shape of this utility model; Figure 6 This is a cross-sectional profile of the moving blade of this utility model; Figure 7 This is a schematic diagram of the free gap in the carbon fiber ring of this utility model; Figure 8 This is a schematic diagram of the sealing structure at the top of the moving blade of this utility model; Figure 9 This is a schematic diagram of the moving blade turbine disk structure of this utility model; Figure 10 This is a schematic diagram of the centroid overlap lines of each interface of the leaf shape of this utility model; In the diagram, 1 - first-stage moving blade turbine disk, 2 - first-stage adjustable stationary blade, 3 - first-stage moving blade tip seal, 4 - second-stage adjustable stationary blade, 5 - second-stage moving blade tip seal, 6 - third-stage adjustable stationary blade, 7 - third-stage moving blade tip seal, 8 - second-stage moving blade turbine disk, and 9 - third-stage moving blade turbine disk. Detailed Implementation

[0013] The present invention will now be described in detail with reference to specific embodiments.

[0014] This invention provides a high-efficiency and durable blast furnace gas TRT expander, which improves the isentropic expansion efficiency of small flow units by 12% to 15% and the isentropic expansion efficiency of large units by 8% to 10%.

[0015] like Figure 1 , 2As shown, the high-efficiency and durable blast furnace gas TRT expander of this utility model adopts a three-stage flow design, including a first-stage adjustable stationary blade 2, a first-stage moving blade turbine disk 1, a second-stage adjustable stationary blade 4, a second-stage moving blade turbine disk 8, a third-stage adjustable stationary blade 6, and a third-stage moving blade turbine disk 9. Under the same root diameter, the use of three-stage flow blades can effectively increase the relative velocity W2 at the outlet in the moving blade velocity triangle. When W2 increases relatively, the moving blade velocity coefficient φ increases in the blade shape with the same reaction degree, and the isentropic expansion efficiency of the moving blade cascade can be improved. The three-stage flow design also effectively reduces the absolute velocity C2 at the gas outlet. According to the formula for total temperature and static temperature: a decrease in the absolute velocity V at the outlet will result in a decrease in the total temperature at the outlet, and a decrease in total temperature means an increase in efficiency.

[0016] In the formula: Th is the total temperature, in °C or K; Tg is the measured temperature, in °C or K; γ is the coefficient of restitution, which has no unit; V is the absolute velocity of the airflow, in m / s; and Cp is the gas pressure specific heat capacity.

[0017] like Figure 3 , 4 As shown, the first-stage adjustable stator blade 2, the second-stage adjustable stator blade 4, and the third-stage adjustable stator blade 6 adopt a post-loaded stator blade design, and the blade profile adopts an airfoil design. The first-stage adjustable stator blade 2, the second-stage adjustable stator blade 4, and the third-stage adjustable stator blade 6 adopt a chord length to blade height ratio of H=1.5C-1.65C, where H is the height and C is the chord length. The maximum thickness D of the blade back arc surface is located at 0.33-0.35 of the total chord length of the blade. The maximum thickness D is 0.27 of the chord length at the blade tip and 0.20 of the chord length at the blade root near the rotor. The blade velocity is loaded in the middle part of the blade. The remaining profiles smoothly transition to the inlet circle R1 and the outlet circle R2. The throat width changes from A to B, and the maximum velocity is loaded at B. This blade profile effectively avoids the generation of secondary flow vortices at the blade tip and root during small flow rate regulation, effectively improving the flow efficiency, and the blade life is not reduced.

[0018] The first-stage turbine disk 1, the second-stage turbine disk 8, and the third-stage turbine disk 9 all adopt a semi-impact blade profile and narrow chord span design. The blade profile is as follows: Figure 5 As shown, the first cross-sectional profile is as follows Figure 6As shown. The inlet α angle of the blade profile at the HUB of the first-stage turbine disk 1, the second-stage turbine disk 8, and the third-stage turbine disk 9 is 65-75°, and the outlet β angle is 30° to 45°. The ratio of the maximum blade thickness D to the chord span C is D / C=0.25, with the remaining sections smoothly transitioning to the inlet circle R1 and the outlet circle R2. The cross-sectional shape of other sections gradually transitions to a thinner airfoil shape (D / C=0.1-0.085) towards the blade tip, with the angle between the top section chord and the root chord between 20-22°. The throat area between the three stages should be determined based on the flow rate and the relative velocity W2. Designers can make fine adjustments based on the flow rate and the mean diameter velocity. The "curve" of the throat area between the three stages should be relatively smooth, except for small flow rate regulation processes. The ratio of blade height H to chord span C should be greater than 1.8, and the number of blades should be 45-52. This blade shape and blade cascade can maintain good fluid flow at the blade root level during both large and small flow rate regulation operations, without generating secondary flow losses on the suction and pressure surfaces, which greatly improves the isentropic expansion efficiency of the flow.

[0019] In blade design, the centroids of the various interfaces overlap at an angle α with the diameter, thus the centroid of the blade interface is not in the diameter direction. When the blade rotates, under centrifugal force, the mass deviating from the diameter will move towards the diameter ray, generating a bending stress on the blade. This stress is opposite to the airflow impact torque. This prestress, or preload force, can counteract the airflow impact force on the blade, preventing the superposition of multiple forces and thus avoiding overload stress, thereby improving blade life. Figure 10 As shown.

[0020] The blade tips on the first-stage moving blade turbine disk 1, the second-stage moving blade turbine disk 8, and the third-stage moving blade turbine disk 9 adopt a conical inclined surface design with a blade tip inclination angle of 17° to 30°. This inclined blade tip and the gap channel between the blade tip and the stationary blade bearing cylinder will generate a conical turbulent layer. This turbulent layer will prevent the airflow from passing over the blade tip and directly entering the next stage, which will greatly suppress and reduce the leakage loss at the blade tip.

[0021] The temperature of blast furnace gas is highly unstable, and the shell deformation is uneven, making the clearance between the blade tip and the stator components crucial. This invention provides a first-stage blade tip seal 3, a second-stage blade tip seal 5, and a third-stage blade tip seal 7 at the blade positions on the first-stage, second-stage, and third-stage blade turbine disks 1 and 8, respectively. Figure 7 , 8As shown, the first-stage moving blade top seal 3, the second-stage moving blade top seal 5, and the third-stage moving blade top seal 7 have the same structure, including a sealing support body and a carbon fiber ring body. The sealing support body is fixed on the stationary blade support cylinder and is used to clamp and fix the carbon fiber ring body. Multiple carbon fiber ring bodies are arranged along the axial direction and embedded in the sealing support body. They are shaped like fingertips and the sealing contact surface with the moving blade adopts the same conical inclined surface design as the moving blade top, with an inclination angle of 17° to 30°.

[0022] This invention employs a fingertip seal design principle for the blade tip seal. The ring matrix is ​​designed based on the principle of light touch and pressure from a human fingertip. When touched, the fingertip will slightly rebound upwards, greatly reducing leakage losses at the blade tip flow surface. This invention uses carbon fiber as the sealing matrix material. Carbon fiber has advantages such as low density, high yield strength, and wear resistance, allowing for a very small blade tip gap of 0.1-0.15mm. Even if it comes into contact with the sealing matrix, it is not a problem. Due to the unique design of the fingertip seal, the upward contraction and deformation of the carbon fiber matrix sealing sheet are guaranteed. This seal is a micro-contact form, but it will not put any burden or affect the blade. The carbon fiber soft contact "fingertip seal" and the special large inclined blade tip of this invention can reduce leakage losses at the blade tip.

[0023] like Figure 9 As shown, the first-stage moving blade turbine disk 1, the second-stage moving blade turbine disk 8, and the third-stage moving blade turbine disk 9 adopt an integral turbine disk design. This utility model, employing an integral turbine disk design, significantly reduces the blade shape error that may arise from the machining of individual blades, avoids blade frequency instability caused by machining errors in the blade root and the blade root groove on the main shaft, and ensures that there is no problem of synchronous vibration between blades. The integrally milled turbine is installed onto the main shaft through thermal expansion caused by heating. The main shaft diameter φ1 has a certain interference fit, generally between +0.8 and +0.85 mm. The turbine bore diameter φ2 is equal to φ1, but without interference fit. When the turbine is heated to approximately 230℃, the bore diameter φ2 increases by about 1.25 mm as the temperature rises. This allows the turbine to be installed into the main shaft with an interference fit. After installation, the turbine is tightly fixed onto the main shaft after cooling.

[0024] Due to the three-stage flow design, the isentropic expansion efficiency is increased, resulting in a significant decrease in the temperature of the final stage of the flow vanes. This leads to severe dew point corrosion of the coal gas. This corrosion reduces the yield strength of the material by 30%–50%. Therefore, this invention uses a suitable titanium alloy as the turbine material. Taking 2Cr13 stainless steel as an example, this material has an ultimate yield strength of 560 MPa. If the sulfur content of the coal gas reaches 2000 ppm, after approximately 20 days of operation, the ultimate yield strength of the material will decrease to 425-430 MPa. In this invention, the first-stage turbine disk 1 and the second-stage turbine disk 8 are made of biaxial precipitation-hardening stainless steel, while the third-stage turbine disk 9 is made of titanium alloy.

[0025] In this embodiment, the first two stages of the three-stage turbine are made of double-precipitation hardening stainless steel S13800, which has a higher overall corrosion resistance than other stainless steel materials. The third stage turbine is made of titanium alloy TC11. The choice of materials depends on the chloride ion content of the gas; if necessary, all stages may need to use TC11 or other grades of titanium alloy. Experiments have verified that the ultimate yield strength of titanium alloy TC11 is 1060 MPa. After six months of use in a gas environment containing 2300 ppm sulfur and 750 ppm chloride ions, the yield strength remained at 1023 MPa, showing virtually no decrease, demonstrating strong resistance to low-temperature corrosion.

[0026] The working principle of this utility model is as follows: blast furnace gas enters through the casing channel. Figure 1 The airflow passes through the first-stage stationary blades to control the flow rate and convert most of the pressure energy into velocity energy. It then enters the first-stage moving blades to do work. After the enthalpy energy decreases, it enters the second-stage stationary blades to adjust the airflow angle of attack to adapt to the second-stage moving blades' incident angle of attack. The airflow then enters the second-stage moving blades to continue doing work. After the enthalpy energy decreases again, it enters the third-stage stationary blades to adjust the airflow angle of attack to adapt to the third-stage moving blades' incident angle of attack. It then enters the third-stage moving blades to continue doing work.

[0027] The content of this utility model is not limited to the embodiments listed. Any equivalent modifications made by those skilled in the art to the technical solution of this utility model after reading this utility model specification shall be covered by the claims of this utility model.

Claims

1. A high-efficiency and durable blast furnace gas TRT expander, characterized in that: The three-stage flow path design includes a first-stage adjustable stationary vane (2), a first-stage moving blade turbine disk (1), a second-stage adjustable stationary vane (4), a second-stage moving blade turbine disk (8), a third-stage adjustable stationary vane (6), and a third-stage moving blade turbine disk (9). The first-stage adjustable stator (2), the second-stage adjustable stator (4), and the third-stage adjustable stator (6) are rear-loaded stator blades, and the blade profile is an airfoil. The first-stage moving blade turbine disk (1), the second-stage moving blade turbine disk (8), and the third-stage moving blade turbine disk (9) all adopt a semi-impact type and a narrow chord spread blade shape.

2. The high-efficiency and durable blast furnace gas TRT expander according to claim 1, characterized in that: The first-level adjustable stationary blade (2), the second-level adjustable stationary blade (4), and the third-level adjustable stationary blade (6) adopt a chord length and blade height ratio of H=1.5C-1.65C, where H is the height and C is the chord length; the maximum thickness D of the curved surface of the blade back is located at 0.33-0.35 of the total chord length of the blade; the maximum thickness D is 0.27 of the chord length at the blade tip and 0.20 of the chord length at the blade root near the rotor.

3. The high-efficiency and durable blast furnace gas TRT expander according to claim 2, characterized in that: The inlet α angle of the profile of the moving blade HUB section of the first-stage moving blade turbine disk (1), the second-stage moving blade turbine disk (8) and the third-stage moving blade turbine disk (9) is 65-75° and the outlet β angle is 30° to 45°; the ratio of the maximum thickness D of the moving blade to the chord span C is D / C=0.

25.

4. The high-efficiency and durable blast furnace gas TRT expander according to claim 3, characterized in that: The blade tips on the first-stage moving blade turbine disk (1), the second-stage moving blade turbine disk (8), and the third-stage moving blade turbine disk (9) are designed with conical inclined surfaces, and the blade tip inclination angle is 17° to 30°.

5. The high-efficiency and durable blast furnace gas TRT expander according to claim 4, characterized in that: The first-stage moving blade turbine disk (1), the second-stage moving blade turbine disk (8) and the third-stage moving blade turbine disk (9) are respectively provided with a first-stage moving blade tip seal (3), a second-stage moving blade tip seal (5) and a third-stage moving blade tip seal (7) at the moving blade position. The first-stage moving blade top seal (3), the second-stage moving blade top seal (5), and the third-stage moving blade top seal (7) have the same structure, including a sealing support body and a carbon fiber ring body; the sealing support body is fixed on the stationary blade support cylinder and is used to clamp and fix the carbon fiber ring body; the carbon fiber ring body is shaped like a fingertip, and the sealing contact surface with the moving blade adopts the same conical inclined surface design as the moving blade top, with an inclination angle of 17° to 30°.

6. The high-efficiency and durable blast furnace gas TRT expander according to claim 5, characterized in that: The first-stage moving blade turbine disk (1), the second-stage moving blade turbine disk (8) and the third-stage moving blade turbine disk (9) adopt an integral turbine disk design.

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