High and medium pressure module of expansion unit of hundred-megawatt adsorption and compression CO2 energy storage system

Abstract

The invention discloses a high and medium pressure module of an expansion unit of a hundred-megawatt CO2 adsorption and compression energy storage system, relates to an expansion unit of an energy storage system, and aims to solve the problems of high compression efficiency loss, poor variable working condition adaptability and insufficient structure compactness of the conventional expansion machine. A high-pressure section of a high-and-medium-pressure outer cylinder is nested outside a high-and-medium-pressure inner cylinder to form a double-layer cylinder structure; the partition plate sleeve is arranged in the medium-pressure section of the high-medium-pressure outer cylinder. The high-and-medium-pressure rotor is arranged at the axis of the high-and-medium-pressure inner cylinder and used for driving the power generator to generate power; the end air seal is used for sealing the contact part of the high and intermediate pressure combined cylinder and the high and intermediate pressure rotor; the high-medium pressure outer cylinder is of a double-air-inlet and tangential-air-inlet volute structure, and the two main air adjusting combination valves are located on the left side and the right side of the high-medium pressure outer cylinder and communicate with a tangential volute of the high-medium pressure outer cylinder. And the reheater is communicated with the high-medium-pressure inner cylinder and the medium-medium-pressure outer cylinder. The invention has the beneficial effects of small compression efficiency loss, strong variable working condition adaptability and strong unit structure compactness.

Description

Technical Field

[0001] This invention relates to an expander unit for an energy storage system. Background Technology

[0002] Wind and solar power generation have advantages such as abundant resources, low environmental pollution, and low technology costs. However, with the continuous increase in the penetration rate of renewable energy, the strong intermittency and regional limitations of wind and solar energy resources have gradually become apparent. The intermittency and randomness of their power generation not only affect the consumption of clean energy but also threaten the stability of the power grid. As a result, energy storage technology has emerged, while large-scale long-term energy storage technology has become a key bottleneck restricting the high-quality development of renewable energy. The existing mainstream physical energy storage technologies include: (1) Pumped hydro storage: the technology is mature but it is heavily dependent on the geographical conditions of high mountains and canyons, making site selection difficult and construction time long (usually 8-10 years); (2) Compressed air energy storage (CAES): it requires the use of underground spaces such as salt caverns and abandoned mines as gas storage facilities, and there are geographical limitations; (3) Liquid air / CO2 energy storage: although it is free from geographical constraints, the liquefaction process has high energy consumption (efficiency is only 35-45%), and the system is not economically viable; (4) Conventional compressed CO2 energy storage: it uses high-pressure storage tanks, but the CO2 density on the low-pressure side is low (about 0.7 kg / m³ at room temperature), resulting in a large gas storage volume, a large land area, and excessive investment costs. None of the above technologies can simultaneously meet the large-scale application requirements of megawatt-level capacity, long-term energy storage (6-12 hours), no geographical limitations, and high round-trip efficiency (>65%).

[0003] In recent years, adsorption-compression CO2 energy storage technology has increased the storage density of low-pressure CO2 to 200-300 kg / m³ through physical adsorption. Combined with high-pressure CO2 artificial storage tanks, it fundamentally eliminates dependence on geological conditions, becoming a highly promising new energy storage route. Its workflow includes an energy storage stage and an energy release stage. In the energy storage stage, CO2 is compressed using off-peak electricity; the high-pressure CO2 is stored in the tank, while the low-pressure CO2 is stored using an adsorbent. In the energy release stage, the high-pressure CO2 generates electricity through an expander, and the final exhaust gas enters the adsorption bed to complete the cycle. This technology theoretically achieves a round-trip efficiency of 68%-72% and can be fully modularized, making it considered an important direction for next-generation long-term energy storage. The expander is the core energy conversion component of the adsorption-compression CO2 energy storage system, and its performance directly determines the overall system efficiency. Existing expander designs face the following challenges:

[0004] (1) Efficiency loss due to large pressure span: The high pressure side of the system reaches more than 10MPa and the low pressure side is about 0.1MPa. The existing cylinder design requires the installation of intermediate reheat pipes, resulting in pressure loss (about 2%-3%), heat dissipation loss (about 1%-2%) and increased footprint.

[0005] (2) Poor adaptability to changing operating conditions: The energy storage system needs to be started and stopped frequently (annual start and stop times > 300 times) and has a wide load regulation (30%-110% of rated load). Conventional impulse turbines use partial intake regulation, which has the following problems: large valve throttling losses (pressure loss of regulating valves reaches 4%-6% under design conditions); partial intake causes airflow vibration, which leads to a reduction in blade fatigue life; thermal stress concentration during rapid load changes affects unit safety.

[0006] (3) Design challenges caused by the characteristics of CO2 working fluid: CO2 has a critical pressure of 7.38 MPa and a critical temperature of 31.1℃. When operating in the near-critical region of the high-pressure section, the density changes drastically (up to 10 times or more). Existing air turbine blades have poor matching performance, which easily leads to airflow separation and shock wave loss. The isentropic efficiency is generally lower than 90%.

[0007] (4) Sealing and leakage issues: Under high pressure difference (ΔP>9MPa), the leakage of existing labyrinth seals can reach 2%-3% of the intake air volume, and the molecular weight of CO2 (44g / mol) is greater than that of air (29g / mol), so the leakage loss is more significant;

[0008] (5) Insufficient structural compactness: The cylinder design results in a large axial length, long bearing span, complex rotor dynamic characteristics, and the critical speed is prone to falling into the working range, and the manufacturing cost is high.

[0009] Therefore, there is an urgent need to develop a high- and medium-pressure module for 100-megawatt expander units that is tailored to the characteristics of CO2 working fluid, and features high efficiency, wide operating condition adaptability, compact structure, and high reliability, in order to support the industrial application of adsorption-compression CO2 energy storage technology. Summary of the Invention

[0010] The purpose of this invention is to solve the problems of large compression efficiency loss, poor adaptability to changing operating conditions, and insufficient compactness of existing expanders, and to propose a high- and medium-pressure module for an expander unit in a 100 MW adsorption compression CO2 energy storage system.

[0011] The high- and medium-pressure module of the expander unit of the 100 MW adsorption-compression CO2 energy storage system described in this invention includes a high- and medium-pressure rotor, a high- and medium-pressure combined cylinder, two pairs of end gas seals, a reheater, and two main gas regulating combined valves.

[0012] The high-pressure and medium-pressure cylinder includes a high-pressure and medium-pressure outer cylinder, a high-pressure and medium-pressure inner cylinder, and a partition sleeve; wherein, the front section of the high-pressure and medium-pressure outer cylinder is a high-pressure section, and the rear section of the high-pressure and medium-pressure outer cylinder is a medium-pressure section; wherein, the high-pressure section of the high-pressure and medium-pressure outer cylinder is nested outside the high-pressure and medium-pressure inner cylinder, forming a double-layer cylinder structure; the partition sleeve is disposed inside the medium-pressure section of the high-pressure and medium-pressure outer cylinder, and the partition sleeve is connected to the high-pressure and medium-pressure inner cylinder end to end along the axial direction;

[0013] The high-pressure rotor is located at the shaft center of the high-pressure inner cylinder and is used to drive the generator to generate electricity.

[0014] The two pairs of end air seals are used to seal the contact area between the high-pressure cylinder and the high-pressure rotor;

[0015] The high-pressure outer cylinder adopts a volute structure with dual air inlets and tangential air inlet. A volute-shaped flow channel is provided on each of the left and right sides. Two main air regulating combined valves are located on the left and right sides of the high-pressure outer cylinder and are connected to the volute-shaped flow channels of the high-pressure outer cylinder respectively.

[0016] Both main gas regulating combined valves are used to introduce high-pressure CO2.

[0017] The reheater's air inlet is connected to the exhaust port of the high- and intermediate-pressure inner cylinder, and the reheater's exhaust port is connected to the air inlet of the intermediate-pressure section of the high- and intermediate-pressure outer cylinder.

[0018] Furthermore, the two pairs of end seals include a pair of front end seals and a pair of rear end seals;

[0019] The pair of front-end air seals are installed on the front and rear sides of the contact area between the high-pressure outer cylinder and the front end of the high-pressure rotor;

[0020] The pair of rear-end air seals are installed on the front and rear sides of the contact area between the high-pressure outer cylinder and the high-pressure rotor.

[0021] Furthermore, the end air seal includes multiple air seal rings; each air seal ring is composed of multiple arc segments with T-shaped roots, and the T-shaped roots are installed in the corresponding fixing grooves of the high-pressure outer cylinder.

[0022] Furthermore, it also includes bearing housing #1 and bearing housing #2;

[0023] The front end of the high-pressure rotor is supported on bearing housing #1 by a radial bearing, and the rear end of the high-pressure rotor is supported on bearing housing #2 by a radial bearing.

[0024] Furthermore, it also includes a first balance ring and a second balance ring;

[0025] The first balance ring is disposed between the high-pressure outer cylinder and the high-pressure inner cylinder, and is close to the front end of the high-pressure rotor;

[0026] The second balance ring is disposed between the high-pressure outer cylinder and the high-pressure inner cylinder, and is close to the partition sleeve.

[0027] Furthermore, the main gas regulating combined valve includes a high-pressure main gas valve and a high-pressure regulating valve;

[0028] The high-pressure main air valve and the high-pressure regulating valve are integrated together; the high-pressure main air valve is a single-seat lift valve with a pre-opening valve, which is opened by a hydraulic motor and closed by spring force; the high-pressure regulating valve is a single-seat balance valve disc, and a balance hole is provided on the single-seat balance valve disc; when the single-seat balance valve disc is fully open, the back of the single-seat balance valve disc is in full circumferential contact with the valve stem sleeve to form a self-sealing structure.

[0029] Furthermore, the high-pressure inner cylinder is formed into a cylindrical cylinder body by alloy steel casting. The first-stage high-pressure stationary blades are horizontally embedded in the inner wall of the volute cavity, and the remaining high-pressure stationary blades are installed in the T-shaped grooves in the high-pressure section of the high-pressure inner cylinder through T-shaped blade roots; the intermediate-stage stationary blades are installed in the various stages of the partition sleeve through T-shaped blade roots.

[0030] Furthermore, the partition sleeve is positioned within the groove on the inner wall of the high-pressure outer cylinder by a bottom key.

[0031] Furthermore, the high-pressure cylinder is provided with a total of 16 stages of reaction flow structure along the axial direction, of which 5 stages of reaction flow structure are provided inside the high-pressure cylinder along the axial direction; and 11 stages of reaction flow structure are provided inside the partition sleeve along the axial direction.

[0032] Furthermore, it also includes high-pressure CO2 storage tanks and low-pressure CO2 adsorption and storage devices;

[0033] The outlet of the high-pressure CO2 storage tank is connected to the inlet of each of the two main gas regulating valves.

[0034] The inlet of the low-pressure CO2 adsorption and storage device is connected to the exhaust port of the medium-pressure section of the high- and medium-pressure inner cylinder.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] The high- and medium-pressure inner cylinder of this invention is a single-stage turbine, and the medium-pressure section of the high- and medium-pressure outer cylinder is a two-stage turbine. The single-stage turbine has 5 flow stages, and the two-stage turbine has 11 flow stages. The high- and medium-pressure combined cylinder uses a high-efficiency reaction-type blade profile. Advanced thermal blade calculation software optimizes the selection of geometric and thermal parameters for each stage within the flow path, reasonably reducing blade width and stage spacing, increasing the number of flow stages, fully leveraging the advantages of impulse-type technology, reducing leakage losses from diaphragm and blade tip seals, and blade secondary flow losses, increasing the reheat coefficient, and improving flow design efficiency. In the flow design of the single-stage and two-stage turbine units, the pressure reaction degree of each stage is uniformly distributed; the enthalpy drop distribution of each stage conforms to the design law, increasing progressively with a uniform upward trend, ensuring flow efficiency. The end seals of the high- and medium-pressure modules all adopt comb-tooth small-gap seals, which can effectively reduce the seal installation gap and reduce leakage losses. Precise clearance control technology during the installation phase involves using finite element analysis and other methods during unit design to calculate the deformation of various components within the high- and intermediate-pressure modules during cold installation and hot operation. During installation, the deflection of the high- and intermediate-pressure cylinder and rotor, as well as the deflection changes of the high- and intermediate-pressure cylinder module in semi-full and full-full cylinder states, are measured to correct and control the gas seal installation clearance. This ensures that the gas seal clearance effectively controls leakage and prevents gas seal rubbing during normal operation. Calculations show that the leakage from the first turbine stage is 1.3171 t / h, and from the second turbine stage it is 7.8185 t / h, totaling 9.1356 t / h, which is 0.9% of the intake airflow, a relatively small percentage. Based on the thermal scheme and main unit flow arrangement, the high-pressure blades consist of five stages, with the first high-pressure stage being a transverse guide vane stage. The aerodynamically calculated flow rate of the high-pressure blades is 1.2% higher than the thermally designed flow rate. The isentropic efficiency (TT) of the high-pressure flow field expansion is 95.9%, indicating good high-pressure flow field matching. The medium-pressure blades consist of 11 stages. Aerodynamic calculations were performed on the flow field of the medium-pressure blades. The calculated flow rate was 2.9% higher than the thermal design flow rate. The isentropic efficiency (TT) of the expansion in the medium-pressure flow field was 96.6%, indicating good flow field matching. The high- and medium-pressure modules of the 100 MW adsorption-compression CO2 energy storage system described in this invention have good flow efficiency. The end-seal gap effectively controls leakage and prevents seal rubbing. The module can adapt to the high-temperature and high-pressure CO2 environment and has high overall strength. Aerodynamically, the airflow trajectory has been optimized to reduce airflow disturbance and resistance, reduce energy loss during intake and exhaust, improve the efficiency of the high- and medium-pressure modules, and thus enhance the power generation efficiency of the entire unit, ensuring stable output. Attached Figure Description

[0037] Figure 1 This is a cross-sectional view of the high- and medium-pressure module of the expander unit of a 100 MW adsorption-compression CO2 energy storage system as described in Specific Embodiment 1.

[0038] Figure 2This is a top view of the high- and medium-pressure module of the expander unit of a 100 MW adsorption-compression CO2 energy storage system in Specific Embodiment 1;

[0039] Figure 3 This is a side view of the high- and medium-pressure module of the expander unit of a 100 MW adsorption-compression CO2 energy storage system in Specific Embodiment 1;

[0040] Figure 4 This is a physical image of the high- and medium-pressure module of the expander unit of a 100 MW adsorption-compression CO2 energy storage system in Specific Implementation Method 1;

[0041] Figure 5 This is a diagram of the sliding pin system in Specific Implementation Method 1;

[0042] Figure 6 This is a schematic diagram of the air intake of the high-pressure outer cylinder in Specific Implementation Method 1;

[0043] Figure 7 This is a physical diagram of the high-pressure mixing cylinder in Specific Implementation Method 1;

[0044] Figure 8 This is a physical diagram of the main gas regulating valve in Specific Implementation Method 1;

[0045] Figure 9 This is a schematic diagram of the reaction blade structure in Specific Implementation Method 1;

[0046] Figure 10 This is a schematic diagram of the structure of the gas seal ring arc segment in the third specific implementation method. Detailed Implementation

[0047] Specific Implementation Method 1: Combination Figures 1 to 9 This embodiment describes a 100 MW adsorption-compression CO2 energy storage system expander unit high- and medium-pressure module, which includes a high- and medium-pressure rotor 2, a high- and medium-pressure combined cylinder, two pairs of end gas seals 3, a reheater, and two main gas regulating combined valves 10.

[0048] The high-pressure and medium-pressure cylinder includes a high-pressure and medium-pressure outer cylinder 5, a high-pressure and medium-pressure inner cylinder 6, and a partition sleeve 8; wherein, the front section of the high-pressure and medium-pressure outer cylinder 5 is a high-pressure section, and the rear section of the high-pressure and medium-pressure outer cylinder 5 is a medium-pressure section; wherein, the high-pressure section of the high-pressure and medium-pressure outer cylinder 5 is nested outside the high-pressure and medium-pressure inner cylinder 6, forming a double-layer cylinder structure; the partition sleeve 8 is disposed inside the medium-pressure section of the high-pressure and medium-pressure outer cylinder 5, and the partition sleeve 8 is connected to the high-pressure and medium-pressure inner cylinder 6 axially end to end;

[0049] The high-pressure rotor 2 is located at the shaft center of the high-pressure inner cylinder 6, and the high-pressure rotor 2 is used to drive the generator to generate electricity.

[0050] The two pairs of end air seals 3 are used to seal the contact area between the high-pressure cylinder and the high-pressure rotor 2;

[0051] The high-pressure outer cylinder 5 adopts a volute structure with dual air inlets and tangential air inlet. A volute-shaped flow channel is provided on each of the left and right sides. Two main air regulating combined valves 10 are located on the left and right sides of the high-pressure outer cylinder 5, respectively, and are connected to the volute-shaped flow channels of the high-pressure outer cylinder 5.

[0052] Both main gas regulating combined valves 10 are used to introduce high-pressure CO2;

[0053] The reheater's air inlet is connected to the exhaust port of the high- and medium-pressure inner cylinder 6, and the reheater's exhaust port is connected to the air inlet of the medium-pressure section of the high- and medium-pressure outer cylinder 5.

[0054] In this embodiment, the high- and medium-pressure module adopts a two-stage expansion plus pre-stage reheat method, the working fluid is CO2, and the unit's external dimensions are 7361mm×7778mm×3097.5mm (length×width×height).

[0055] The high- and medium-pressure inner cylinder is a single-stage turbine, and the medium-pressure section of the high- and medium-pressure outer cylinder is a two-stage turbine. The inlet of the single-stage turbine is in sliding pressure operation, with an intake flow rate of 280 kg / s and an intake sliding pressure range of 10.0 MPa to 6.5 MPa. The main gas temperature and reheat temperature are 310℃. It is designed for two-stage flow, with high-pressure flow followed by medium-pressure flow in the order of pressure decrease.

[0056] The high- and medium-pressure module has an inlet air temperature of 310℃, an inlet air pressure of 7.9MPa, an outlet air temperature of 144.7℃, and an outlet pressure of 0.75MPa. This high- and medium-pressure module has a combined high- and medium-pressure cylinder with 5+11 stages and the following main technical features:

[0057] (1) The reaction flow technology and thermal blade calculation program ensure that the module has higher flow efficiency;

[0058] (2) Small-diameter multi-stage blade cascade, high flow efficiency, and low rotor stress;

[0059] (3) The “T” type blade root structure can reduce axial air leakage loss;

[0060] (4) Full-circumference intake mode without regulating stage, reducing valve loss and part of the intake loss;

[0061] (5) The large axial clearance and small radial clearance of the flow passage are beneficial to the rapid start-up and load change of the turbine, and can also ensure that the unit has a high flow passage efficiency;

[0062] (6) The high-pressure cylinder has a compact and robust structure with a small blade width, which can effectively shorten the total length of the unit;

[0063] (7) The high-pressure main gas regulating combined valve 10 developed by model adopts a structure of two main gas valves and regulating valves;

[0064] (8) The valve adopts an excellent diffuser flow channel design, with low pressure loss. The valve has tangential air intake, compact structure, low pressure loss, and is easy to maintain.

[0065] (9) The high-pressure main gas regulating combined valve 10 has a structure and layout that are conducive to improving unit efficiency and reducing losses;

[0066] (10) The medium-pressure valve adopts a hydraulic butterfly valve;

[0067] (11) The air intake section of the unit not only meets the performance requirements, but also makes its structure compact, neat and beautiful, and the turbine operating layer appears wide and unobstructed;

[0068] (12) Optimize the intake and exhaust profiles to reduce intake and exhaust losses.

[0069] The front section of the intermediate-high pressure combined cylinder is the high-pressure section (single-stage turbine), which adopts a double-cylinder structure to increase unit stability. The rear section of the intermediate-high pressure combined cylinder is the intermediate-pressure section (two-stage turbine). The intermediate-pressure section has a diaphragm sleeve structure, which is simple in structure and easy to maintain. It adopts a reaction-type flow design and has no regulating stage. The intermediate-high pressure outer cylinder 5 adopts a tangential volute air intake method, and there is a main air regulating combined valve 10 on each side connected to the tangential volute of the intermediate-high pressure outer cylinder 5.

[0070] The intermediate and high-pressure modules are integrally cast. The front section of the intermediate and high-pressure combined cylinder has a double-layer cylinder structure for better stability, while the rear intermediate-pressure section has a partition sleeve structure. Both adopt a reaction-type flow design with no regulating stages, totaling 16 stages, including 5 stages in stage 1 and 11 stages in stage 2. The two air inlets of stage 1 are located on the left and right sides of the intermediate and high-pressure combined cylinder (upper left and lower right, viewed from the turbine towards the generator). The main air enters the intermediate and high-pressure outer cylinder 5 directly through the high-pressure main air regulating combined valve 10. The exhaust port is located at the lower part of the intermediate and high-pressure inner cylinder 6. The gas that has completed its work enters the reheater through the exhaust port. After being heated, the gas enters the stage 2 turbine through the two air inlets at the bottom of the intermediate and high-pressure outer cylinder 5 via the intermediate-pressure reheat valve. The compressed CO2 is discharged after completing its work in the stage 2 turbine through 11 reaction-type pressure stages.

[0071] The high- and medium-pressure module is designed as a combined high- and medium-pressure cylinder structure, with the following technical features:

[0072] (1) The flow path adopts reaction-type full three-dimensional design technology to further improve the cylinder pressing efficiency;

[0073] (2) Tangential full-circumference air intake, throttling regulation, and sliding pressure operation improve the unit's economy;

[0074] (3) The moving blades at each stage adopt inverted T-shaped blade roots, resulting in less air leakage loss;

[0075] (4) The high-pressure outer cylinder 5 adopts a 2×180° tangential volute inlet technology: the volute structure reduces flow losses at the inlet and optimizes the gas outlet of the first-stage radial blades. Gas flows into the blades without sudden changes in velocity and direction. The flow loss on the volute is significantly reduced, allowing for higher gas flow rates and high kinetic energy conversion efficiency. This improvement in the flow channel structure allows the turbine to adopt a compact and robust structure.

[0076] The high-pressure external cylinder 5 intake system employs a double-sided tangential volute structure to reduce the tangential non-uniformity of the first-stage guide vane inlet parameters and improve efficiency. The volute structure reduces flow losses at the inlet and optimizes the exit of the first-stage vanes. The significantly reduced flow loss on the volute allows for higher gas velocities and high kinetic energy conversion efficiency.

[0077] The unit is equipped with two high-pressure main gas regulating combined valves 10 to control the gas flow rate entering the high-pressure intake.

[0078] The partition sleeve 8 is composed of two halves. It rests on the groove of the lower horizontal split surface of the high-pressure cylinder by the external supports on both sides of the lower horizontal split surface, and is positioned at the bottom by a shim, which also ensures that the partition sleeve 8 is fixed in the lateral position relative to the high-pressure cylinder. The partition sleeve 8 is axially positioned in the groove of the inner wall of the high-pressure section of the high-pressure outer cylinder 5 by a key, which ensures that the partition sleeve 8 can freely expand and contract with temperature changes.

[0079] The partition sleeve 8 is made of alloy steel casting, which can adapt to its high temperature and high pressure CO2 environment and improve the overall strength.

[0080] Specific Implementation Method 2: This implementation method further defines the high and medium pressure module of the expander unit of the 100 MW adsorption compression CO2 energy storage system described in Specific Implementation Method 1. In this implementation method, the two pairs of end gas seals 3 include a pair of front gas seals and a pair of rear gas seals.

[0081] The pair of front-end air seals are installed on the front and rear sides of the contact area between the high-pressure outer cylinder 5 and the high-pressure rotor 2;

[0082] The pair of rear-end air seals are installed on the front and rear sides of the contact area between the high-pressure outer cylinder 5 and the high-pressure rotor 2.

[0083] In this embodiment, the design of front and rear double seals achieves a balance between leakage control, thrust balance and safe operation under high pressure differential conditions at the megawatt level.

[0084] Specific Implementation Method Three: Combination Figure 10This embodiment further defines the high- and medium-pressure module of the expander unit of the 100 MW adsorption-compression CO2 energy storage system described in Specific Embodiment 1. In this embodiment, the end gas seal (3) includes multiple gas seal rings; each gas seal ring is composed of multiple arc segments (14) with T-shaped roots, and the T-shaped roots are installed in the corresponding fixed grooves of the high- and medium-pressure outer cylinder (5).

[0085] In this embodiment, the outer ring of the end air seal 3 is embedded in a special groove in the inner hole of the high-pressure outer cylinder 5; the inner ring of the end air seal 3 forms a small radial gap with the journal of the high-pressure rotor 2; that is, the end air seal 3 and the high-pressure outer cylinder 5 are both stationary components, rigidly connected by the groove; the end air seal 3 and the high-pressure rotor 2 cooperate to form a dynamic and static seal; the end air seals 3 of the high-pressure module all adopt comb-tooth small-gap air seals, which can effectively reduce the air seal installation gap and reduce leakage loss. The precise gap control technology during the installation stage calculates the deformation of each component inside the high-pressure module during cold installation and hot operation of the unit through analysis methods such as finite element method during unit design, and corrects and controls the air seal installation gap by measuring the deflection of the high-pressure cylinder and rotor, as well as the deflection change of the high-pressure cylinder in the semi-full cylinder and full cylinder states during installation, to ensure that the air seal gap can effectively control the leakage and effectively avoid air seal collision during normal operation of the unit.

[0086] To ensure turbine efficiency and shaft stability, the number of sections and the number of teeth in each section of the end seal 3 should be reasonably distributed. A high-pressure balance hub is installed on the turbine inlet side of the first section of the end seal 3, and the pressure after the high-pressure balance hub is connected to the exhaust pressure of the first section of the turbine. A medium-pressure balance hub is installed on the exhaust side of the first section of the turbine, and the pressure after the medium-pressure balance hub is connected to the exhaust pressure of the second section of the turbine. A low-pressure balance hub is installed before the second section of the turbine, and the pressure before the low-pressure balance hub is connected to the exhaust pressure of the first section of the turbine.

[0087] In this embodiment, the end air seal 3 includes multiple air seal rings with a reasonable air seal gap, meeting both economic and safety requirements, and facilitating maintenance. Each air seal ring consists of eight arc segments 14 with "T"-shaped roots, which are installed into corresponding slots in the high-pressure cylinder. The air seal rings are fixed to the high-pressure cylinder at the horizontal split surface using locking screws. (See assembly instructions.) Figure 10 .

[0088] Each air seal ring has eight spring plates on its back. These spring plates press the air seal ring firmly against the sealing surface of the air seal ring groove, ensuring the radial clearance between the air seal plate and the rotor. When the unit is running or there is dynamic and static friction, the air seal ring can retract to prevent excessive wear.

[0089] Each arc segment 14 has a pressure supply groove on the air intake side to use the air pressure difference between the outer and inner sides to radially position the air seal ring. For easy identification, a number mark should be made on the mating surface at the end of each arc segment 14. When the air seal ring is disassembled and reassembled, each arc segment 14 of the air seal ring must be installed in its original position.

[0090] The air seal ring and the air seal plate on the rotor form a pressure-reducing flow channel, reducing air leakage loss.

[0091] Specific Implementation Method 4: This implementation method further defines the high and medium pressure module of the expander unit of the 100 MW adsorption compression CO2 energy storage system described in Specific Implementation Method 1. In this implementation method, it also includes bearing housing 1 and bearing housing 9.

[0092] The front end of the high-pressure rotor 2 is supported on bearing housing 1 by a radial bearing, and the rear end of the high-pressure rotor 2 is supported on bearing housing 9 by a radial bearing.

[0093] In this embodiment, the high-pressure outer cylinder 5 is supported on bearing housing 1 using a lower claw-shaped support. The claws of the lower cylinder are raised above the split surface, and their supporting surface is flush with the horizontal split surface of the high-pressure outer cylinder. CNC milling is used to ensure the flushness of the two surfaces. The claws rest on the keys located on both sides of bearing housings 1 and 2. This improves the stress distribution on the split surface bolts, increases the rigidity of the high-pressure outer cylinder, and prevents the split surface from opening and deforming.

[0094] At the front and rear ends of the high-pressure and intermediate-pressure module, the high-pressure and intermediate-pressure cylinders are connected to the adjacent bearing housings by centering beams 13, which are fixed to the high-pressure and intermediate-pressure cylinders and adjacent bearings by bolts and locating pins. These centering beams 13 ensure the correct axial and lateral positioning of the high-pressure and intermediate-pressure cylinders relative to the bearing housings. Each claw is connected to the bearing housing with a double-ended bolt to prevent the high-pressure and intermediate-pressure cylinder from coming loose from the bearing housing. An appropriate gap is left between the nut and the claw, allowing the high-pressure and intermediate-pressure cylinder claws to expand and contract freely when the temperature changes. A transverse pin 11 is provided on the bearing housing along the radial direction of the high-pressure and intermediate-pressure rotor 2; a longitudinal pin 12 is provided along the axial direction of the high-pressure and intermediate-pressure rotor 2; the intersection of the axis of the transverse pin 11 and the axis of the longitudinal pin 12 is the dead point of the high-pressure and intermediate-pressure cylinder.

[0095] Specific Implementation Method 5: This implementation method further defines the high and medium pressure module of the expander unit of the 100 MW adsorption compression CO2 energy storage system described in Specific Implementation Method 1. In this implementation method, it also includes a first balance ring 4 and a second balance ring 7.

[0096] The first balance ring 4 is disposed between the high-pressure outer cylinder 5 and the high-pressure inner cylinder 6, and is close to the front end of the high-pressure rotor 2;

[0097] The second balance ring 7 is disposed between the high-pressure outer cylinder 5 and the high-pressure inner cylinder 6, and is close to the partition sleeve 8.

[0098] In this embodiment, the arrangement of the first balancing ring 4 and the second balancing ring 7 balances the axial thrust: the reasonable arrangement of the first balancing ring 4 (high pressure section) and the second balancing ring 7 (medium pressure section) effectively balances the huge axial thrust generated by the high pressure difference; reduces bearing load: the first balancing ring 4 and the second balancing ring 7 convert part of the pressure energy into balancing force, reducing the load on the thrust bearing and improving bearing life and reliability; optimizes leakage control: the pressure after the first balancing ring 4 and the second balancing ring 7 is connected to different pressure stages, forming a step-by-step pressure reduction, reducing leakage from the high pressure side to the medium pressure side.

[0099] Specific Implementation Method Six: This implementation method further defines the high and medium pressure module of the expander unit of the 100 MW adsorption compression CO2 energy storage system described in Specific Implementation Method One. In this implementation method, the main gas regulating combined valve 10 includes a high pressure main gas valve and a high pressure regulating valve.

[0100] The high-pressure main air valve and the high-pressure regulating valve are integrated together; the high-pressure main air valve is a single-seat lift valve with a pre-opening valve, which is opened by a hydraulic motor and closed by spring force; the high-pressure regulating valve is a single-seat balance valve disc, and a balance hole is provided on the single-seat balance valve disc; when the single-seat balance valve disc is fully open, the back of the single-seat balance valve disc is in full circumferential contact with the valve stem sleeve to form a self-sealing structure.

[0101] In this embodiment, the high-pressure main air regulating combined valve 10 includes a high-pressure main air valve and a high-pressure regulating valve. The high-pressure main air valve and the high-pressure regulating valve are installed within the same valve body but perform different functions. The high-pressure main air valve is a single-seat lift valve with an internal pre-opening valve, and the high-pressure regulating valve is a single-seat balance valve. The high-pressure regulating valve is connected to the intermediate-high pressure outer cylinder 5 via an inlet flange. Main air leaves the high-pressure regulating valve and enters the intermediate-high pressure outer cylinder 5 through an inlet duct. The inlet duct between the high-pressure main air regulating combined valve 10 and the intermediate-high pressure outer cylinder 5 is very short, which is beneficial for controlling the rapid increase in speed caused by the closure of the high-pressure main air valve.

[0102] The primary function of a high-pressure regulating valve is to provide protection in the event of an impending emergency. It closes when the turbine protection system activates. A secondary function is to control the reheat gas flow during turbine startup and load increases. The high-pressure main gas valve is designed to close quickly in emergencies to cut off gas supply to the high-pressure cylinder.

[0103] The high-pressure main air valve is part of the safety system and is designed for "force-operated opening." The force and torque applied to the high-pressure main air valve by the main intake pipe are transmitted to the foundation via the intermediate and high-pressure outer cylinder 5 and the valve support. The design philosophy of the high-pressure main air valve and the high-pressure regulating valve is to facilitate maintenance and minimize valve pressure loss. Gas enters the valve body containing a permanent filter. When the high-pressure main air valve is closed, the gas fills the valve body and remains outside the valve disc. When the high-pressure main air valve opens, the valve stem drives the pre-opening valve to open first, thereby reducing the lifting force required to open the main air valve disc, so that the main air valve disc can open smoothly. The high-pressure main air valve is designed with a valve limit mechanism, and when the valve is fully open, the back of the valve disc is in full circumferential contact with the valve stem sleeve, forming a self-sealing seal. The high-pressure main air valve is opened by a hydraulic actuator and closed by spring force. The high-pressure regulating valve has a balance hole on the valve disc to reduce the lifting force required to open the valve during unit operation. The high-pressure regulating valve is also designed with a valve limit mechanism, forming a self-sealing seal when the valve is fully open. Similarly, the high-pressure regulating valve is opened by a hydraulic actuator and closed by spring force, so that the high-pressure main air valve and the high-pressure regulating valve can be quickly closed in the event of a system or turbine failure, ensuring safety.

[0104] The high-pressure main gas regulating valve has very low overall pressure loss, good economic efficiency, and can meet the requirements of maximum flow rate. Moreover, its force is very small throughout the entire stroke range, which can ensure the safe and stable operation of the valve.

[0105] Specific Implementation Method Seven: This implementation method further defines the high- and medium-pressure module of the expander unit of the 100 MW adsorption-compression CO2 energy storage system described in Specific Implementation Method One. In this implementation method, the high- and medium-pressure inner cylinder 6 is formed into a cylindrical cylinder body by alloy steel casting. The first-stage high-pressure stationary blades are horizontally embedded in the inner wall of the volute cavity. The remaining high-pressure stationary blades are installed in the T-shaped grooves on the inner wall of the high- and medium-pressure inner cylinder 6 through T-shaped blade roots. The intermediate-stage stationary blades are installed in the various stages of the partitions of the partition sleeve 8 through T-shaped blade roots.

[0106] In this embodiment, both the high-pressure outer cylinder 5 and the high-pressure inner cylinder 6 are cast and divided into upper and lower halves. The horizontal split surface is secured with bolts, and the upper and lower halves of the high-pressure cylinder are tightened and sealed with double-ended bolts. High-pressure stationary blades are installed on the inner wall of the high-pressure inner cylinder 6; the inner wall of the medium-pressure section of the high-pressure outer cylinder 5 is provided with recesses for partition sleeves 8, and there are recesses for installing air seals and corresponding air extraction ports at both the front and rear ends.

[0107] The high-pressure inner cylinder 6 is cast from high-temperature alloy steel and forms two nearly cylindrical halves, capable of withstanding high temperatures and pressures of CO2. To ensure the sealing of the joint surfaces of the high-pressure inner cylinder 6, a bolt-sealed system is used. Specifically, the intake area employs a bolt-sealed flange connection structure, with the bolts positioned as close to the center as possible. To avoid interference with the intake port, the bolt holes are designed as threaded holes. Specialized heating tools and support components are required for installation and disassembly. Stationary vanes are fixed to the high-pressure inner cylinder 6. The first-stage stationary vanes are horizontally embedded in the inner wall of the volute chamber (i.e., horizontally placed stationary vanes), providing good intake performance together with the volute air passage. The remaining stationary vanes are inserted into the T-shaped grooves on the inner wall of the high-pressure inner cylinder 6 through their blade roots and pre-tightened to form a single unit. This method avoids the impact of diaphragm welding deformation on flow smoothness, ensuring consistency between design and installation.

[0108] Specific Implementation Method Eight: This implementation method further defines the high- and medium-pressure module of the expander unit of the 100 MW adsorption-compression CO2 energy storage system described in Specific Implementation Method One. In this implementation method, the partition sleeve 8 is positioned in the groove of the inner wall of the high- and medium-pressure inner cylinder 6 by a bottom key.

[0109] In this embodiment, the partition sleeve 8 has the following advantages: good thermal expansion freedom: the bottom key positioning allows the partition sleeve 8 to expand and contract freely along the axial direction with temperature changes, avoiding thermal stress concentration; accurate installation and positioning: the bottom key and the surrounding groove cooperate to ensure that the lateral position of the partition sleeve 8 relative to the intermediate pressure section of the high-pressure outer cylinder 5 is fixed, simplifying the assembly process; simple and reliable structure: compared with the complex connection structure, the bottom key positioning method is simple, improving maintainability and operational reliability.

[0110] Specific Implementation Method Nine: This implementation method further defines the high- and medium-pressure module of the expander unit of the 100 MW adsorption-compression CO2 energy storage system described in Specific Implementation Method One. In this implementation method, the high- and medium-pressure inner cylinder 6 is provided with a total of 16 stages of reaction flow structure along the axial direction. Among them, 5 stages of reaction flow structure are provided in the interior of the high- and medium-pressure inner cylinder 6 along the axial direction; and 11 stages of reaction flow structure are provided in the interior of the partition sleeve 8 along the axial direction.

[0111] In this embodiment, a 16-stage reaction flow design is adopted. By increasing the number of stages and rationally distributing the enthalpy drop at each stage (increasing progressively and with a uniform upward trend), the advantages of reaction technology are fully utilized. The flow fields of the high-pressure section (5 stages) and the medium-pressure section (11 stages) are well matched, with the isentropic efficiency of the high-pressure flow field reaching 95.9% and that of the medium-pressure flow field reaching 96.6%. The flow path reheat coefficient is increased, effectively reducing leakage losses from the diaphragm gas seal and blade tip gas seal, as well as secondary flow losses from the blades. It adapts to the characteristics of CO2 working fluid: considering the drastic density change of CO2 in the near-critical region (up to 10 times or more), the multi-stage design makes the pressure reaction degree distribution more uniform, avoiding airflow separation and shock wave losses. Compared with air turbines, the isentropic efficiency can be improved from generally below 90% to above 95%. Leakage control is optimized: the segmented design, combined with the balance ring structure, forms a progressive pressure reduction, reducing the total leakage to 9.1356 t / h, which is only the inlet flow rate. 0.9%; Matching of dynamic and static sealing structures at each stage reduces leakage from the high-pressure side to the medium-pressure side; Balancing economy and safety: The small-diameter multi-stage blade design reduces rotor stress, and the critical speed avoids the working range. The design features large axial clearance and small radial clearance, which is beneficial for rapid start-up and load changes (annual start-up and shutdown >300 times) while ensuring high efficiency; Modularity and compactness: The 16 stages are integrated into a high- and medium-pressure combined cylinder structure, which eliminates the pressure loss (approximately 2-3%) and heat dissipation loss (approximately 1-2%) of the intermediate reheat pipeline compared to the separate cylinder design; Shortening the axial length reduces the bearing span, improves rotor dynamic characteristics, and reduces manufacturing costs; Through precise aerodynamic calculations and stage optimization, this design achieves a system round-trip efficiency target of >65% at a capacity of hundreds of megawatts, while meeting the operational requirements of long-term energy storage (6 hours-12 hours) and wide load regulation (30%-110%).

[0112] Specific Implementation Method 10: This implementation method further defines the high and medium pressure module of the expander unit of the 100 MW adsorption compression CO2 energy storage system described in Specific Implementation Method 1. In this implementation method, it also includes a high pressure CO2 storage tank and a low pressure CO2 adsorption storage device.

[0113] The outlet of the high-pressure CO2 storage tank is connected to the inlet of each of the two main gas regulating combined valves 10.

[0114] The inlet of the low-pressure CO2 adsorption and storage device is connected to the exhaust port of the medium-pressure section of the high-medium-pressure inner cylinder 6.

[0115] In this embodiment, the connection between the high-pressure CO2 storage tank and the low-pressure adsorption gas storage device is clearly defined by the above settings, forming a complete closed loop of the energy storage system; modular application is convenient: it can be directly connected to the gas storage and adsorption units of the adsorption compression CO2 energy storage system, which is convenient for engineering implementation; energy conversion is highly efficient: through short-distance pipeline connection, pipeline pressure loss and heat loss are reduced, and the overall round-trip efficiency of the system is improved (up to 68%-72%).

[0116] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high- and medium-pressure module for an expander unit in a 100 MW adsorption-compression CO2 energy storage system, characterized in that, It includes a high-pressure rotor (2), a high-pressure cylinder, two pairs of end seals (3), a reheater, and two main gas regulating valves (10). The high-pressure cylinder includes a high-pressure outer cylinder (5), a high-pressure inner cylinder (6), and a partition sleeve (8); wherein, the front section of the high-pressure outer cylinder (5) is a high-pressure section, and the rear section of the high-pressure outer cylinder (5) is a medium-pressure section; wherein, the high-pressure section of the high-pressure outer cylinder (5) is nested outside the high-pressure inner cylinder (6) to form a double-layer cylinder structure; the partition sleeve (8) is set inside the medium-pressure section of the high-pressure outer cylinder (5), and the partition sleeve (8) is connected to the high-pressure inner cylinder (6) axially end to end; The high-pressure rotor (2) is located at the shaft center of the high-pressure inner cylinder (6), and the high-pressure rotor (2) is used to drive the generator to generate electricity; The two pairs of end air seals (3) are used to seal the contact parts between the high-pressure cylinder and the high-pressure rotor (2); The high-pressure outer cylinder (5) adopts a volute structure with double air inlets and tangential air inlet. A volute-shaped flow channel is provided on each of the left and right sides. Two main air regulating combined valves (10) are located on the left and right sides of the high-pressure outer cylinder (5) respectively, and are connected to the volute-shaped flow channels of the high-pressure outer cylinder (5). Both main gas regulating combined valves (10) are used to introduce high-pressure CO2; The reheater’s air inlet is connected to the exhaust port of the high-pressure inner cylinder (6), and the reheater’s exhaust port is connected to the air inlet of the medium-pressure section of the high-pressure outer cylinder (5).

2. The high- and medium-pressure module of the expander unit of a 100 MW adsorption-compression CO2 energy storage system according to claim 1, characterized in that, The two pairs of end seals (3) include a pair of front end seals and a pair of rear end seals; The pair of front-end air seals are installed on the front and rear sides of the contact area between the high-pressure outer cylinder (5) and the high-pressure rotor (2); The pair of rear-end air seals are installed on the front and rear sides of the contact area between the high-pressure outer cylinder (5) and the high-pressure rotor (2).

3. The high- and medium-pressure module of the expander unit of a 100 MW adsorption-compression CO2 energy storage system according to claim 1, characterized in that, The end air seal (3) includes multiple air seal rings; each air seal ring is composed of multiple arc segments (14) with T-shaped roots, and the T-shaped roots are installed in the corresponding fixed grooves of the high and medium pressure outer cylinder (5).

4. The high- and medium-pressure module of the expander unit of a 100 MW adsorption-compression CO2 energy storage system according to claim 1, characterized in that, It also includes bearing housing #1 (1) and bearing housing #2 (9); The front end of the high-pressure rotor (2) is supported on bearing housing (1) #1 by a radial bearing, and the rear end of the high-pressure rotor (2) is supported on bearing housing (9) #2 by a radial bearing.

5. The high- and medium-pressure module of the expander unit of a 100 MW adsorption-compression CO2 energy storage system according to claim 1, characterized in that, It also includes a first balancing ring (4) and a second balancing ring (7); The first balance ring (4) is disposed between the high-pressure outer cylinder (5) and the high-pressure inner cylinder (6), and is close to the front end of the high-pressure rotor (2); The second balance ring (7) is located between the high-pressure outer cylinder (5) and the high-pressure inner cylinder (6), and is close to the partition sleeve (8).

6. The high- and medium-pressure module of the expander unit of a 100 MW adsorption-compression CO2 energy storage system according to claim 1, characterized in that, The main gas regulating combined valve (10) includes a high-pressure main gas valve and a high-pressure regulating valve; The high-pressure main air valve and the high-pressure regulating valve are integrated together; the high-pressure main air valve is a single-seat lift valve with a pre-opening valve, which is opened by a hydraulic motor and closed by spring force; the high-pressure regulating valve is a single-seat balance valve disc, and a balance hole is provided on the single-seat balance valve disc; when the single-seat balance valve disc is fully open, the back of the single-seat balance valve disc is in full circumferential contact with the valve stem sleeve to form a self-sealing structure.

7. The high- and medium-pressure module of the expander unit of a 100 MW adsorption-compression CO2 energy storage system according to claim 1, characterized in that, The high-pressure inner cylinder (6) is formed into a cylindrical cylinder body by alloy steel casting. The first-stage high-pressure stationary blades are horizontally embedded in the inner wall of the volute cavity. The remaining high-pressure stationary blades are installed in the T-shaped grooves of the high-pressure section inner wall of the high-pressure inner cylinder (6) through T-shaped blade roots. The intermediate-stage stationary blades are installed in the various stages of the partitions of the partition sleeve (8) through T-shaped blade roots.

8. The high- and medium-pressure module of the expander unit of a 100 MW adsorption-compression CO2 energy storage system according to claim 1, characterized in that, The partition sleeve (8) is positioned in the groove on the inner wall of the high-pressure outer cylinder (5) by a bottom key.

9. The high- and medium-pressure module of the expander unit of a 100 MW adsorption-compression CO2 energy storage system according to claim 1, characterized in that, The high-pressure cylinder has a total of 16 levels of reaction flow structure along the axial direction. Among them, there are 5 levels of reaction flow structure in the high-pressure cylinder (6) and 11 levels of reaction flow structure in the partition sleeve (8).

10. The high- and medium-pressure module of the expander unit of a 100 MW adsorption-compression CO2 energy storage system according to claim 1, characterized in that, It also includes high-pressure CO2 storage tanks and low-pressure CO2 adsorption and storage devices; The outlet of the high-pressure CO2 storage tank is connected to the inlet of the two main gas regulating valves (10); The inlet of the low-pressure CO2 adsorption and storage device is connected to the exhaust port of the medium-pressure section of the high-pressure inner cylinder (6).

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