Multi-stage steam coupled steam turbine power generation system and method based on temperature gradient of kiln waste heat

Abstract

The application discloses a multi-stage steam coupling steam turbine power generation system and method based on kiln waste heat temperature gradient, relates to the technical field of industrial waste heat recovery and heat-electricity conversion, and comprises a kiln, a waste heat gradient collection subsystem, a multi-stage waste heat boiler subsystem, a multi-radial inlet coupling steam turbine subsystem, a generator and an intelligent monitoring and coordinated control subsystem; a plurality of waste heat collection openings are arranged along the length direction of the kiln, waste heat in different temperature intervals is collected in stages, and steam with different pressure and temperature grades is generated respectively; and each stage of steam enters corresponding pressure stages through corresponding radial inlets arranged along the axial direction of the steam turbine to do work. The application improves heat source matching, steam utilization efficiency and system operation stability, reduces tail waste heat waste, and has good energy-saving and efficiency-improving effects through the cascade utilization of kiln waste heat and the combination of multi-stage steam coupling power generation and intelligent coordinated control.

Description

Technical Field

[0001] This invention relates to the field of industrial waste heat recovery and thermoelectric conversion technology, and in particular to a multi-stage steam-coupled turbine power generation system and method based on the temperature gradient of waste heat from kilns. Background Technology

[0002] As crucial thermal equipment in industries such as ceramics, cement, glass, brick and tile, and metallurgy, kilns exhibit a distinct temperature gradient along the material's path during continuous operation. Typically, the firing zone has the highest temperature, decreasing sequentially through the preheating zone, cooling zone, and kiln tail exhaust area. The waste heat and heat loss from the exhaust gases in different sections vary significantly in temperature level, heat grade, and usability. In other words, kiln waste heat is not a uniform heat source but rather a gradient heat source that continuously varies along its length.

[0003] Most existing technologies for utilizing waste heat from kilns involve collecting waste heat from multiple sections and feeding it into a single waste heat boiler for recovery, then using the steam from a single parameter to drive a conventional steam turbine to generate electricity. While such solutions can achieve partial waste heat recovery, they still have significant shortcomings: First, waste heat of different temperature grades is mixed before entering the same waste heat boiler, with high-grade and low-grade heat energy being diluted, easily leading to a decrease in heat energy grade and loss of usable energy. Second, a single waste heat boiler can usually only output steam at a single pressure and temperature grade, making it difficult to adapt to the gradient distribution of waste heat along the kiln and failing to achieve graded matching between heat source and steam parameters. Third, traditional steam turbines mostly adopt a single-inlet steam structure, which has high requirements for inlet steam parameters and cannot simultaneously accept steam of multiple pressure grades, resulting in the inability to effectively utilize graded steam at the power conversion end even if it is formed at the front end. Fourth, the low-temperature waste heat in the later section of the kiln cooling zone and the kiln tail area is often difficult to meet the effective utilization conditions of conventional steam power generation systems due to its low grade, and is therefore directly discharged, resulting in serious waste of low-temperature waste heat. To address this, we propose a multi-stage steam-coupled steam turbine power generation system and method based on the temperature gradient of kiln waste heat. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-stage steam-coupled turbine power generation system and method based on the temperature gradient of waste heat from a kiln, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a multi-stage steam-coupled turbine power generation system based on the waste heat temperature gradient of a kiln, comprising: Kiln; The waste heat gradient acquisition subsystem has N waste heat acquisition ports along the length of the kiln, where N≥3. Each waste heat acquisition port corresponds to the waste heat discharge location in different temperature ranges of the kiln, and is used to collect waste heat at different temperature levels in stages. The multi-stage waste heat boiler subsystem includes N waste heat boilers connected one-to-one with the N waste heat collection ports. Each waste heat boiler generates steam with different pressures and different temperature levels according to the temperature level of the received waste heat. A multi-radial steam inlet coupled steam turbine subsystem includes a steam turbine body. The steam turbine body has M radial steam inlets at different positions along the axial direction, where M≥2. Each radial steam inlet corresponds to a different pressure level inside the steam turbine. Steam of different pressure and temperature levels enters the corresponding pressure level of the steam turbine through the corresponding radial steam inlet and expands to do work in each downstream level. The generator is connected to the turbine body via a transmission. The intelligent monitoring and coordination control subsystem is used to coordinate and control the steam intake of each waste heat boiler and each radial steam inlet based on the real-time waste heat parameters and steam parameters at each waste heat collection port, so as to achieve coordinated matching between the gradient utilization of waste heat in the kiln and the multi-stage steam intake work of the steam turbine.

[0006] Preferably, the waste heat collection port includes at least three or more of the following: high temperature section collection port, medium-high temperature section collection port, medium temperature section collection port, and medium-low temperature section collection port, which are respectively set at corresponding positions in the kiln firing zone, the transition area between the firing zone and the cooling zone, the front section of the cooling zone, the middle and rear sections of the cooling zone, and the kiln tail flue gas area. Each of the aforementioned waste heat collection ports is equipped with a high-temperature resistant heat collection hood or flue gas collection pipe, and is equipped with a temperature sensor, flow sensor and regulating valve for real-time collection of waste heat temperature and flow parameters and adjustment of waste heat extraction amount.

[0007] Preferably, each of the waste heat boilers is equipped with an independent feedwater system, steam drum or once-through evaporation system, blowdown device and safety valve. The waste heat boiler that receives waste heat from the high-temperature section is also equipped with a superheater to output high-pressure superheated steam. Feedwater cascade preheating pipelines are installed between waste heat boilers at each level. The higher-temperature feedwater discharged from the low-temperature waste heat boiler is used as the preheating feedwater for the higher-temperature waste heat boiler, thus forming a feedwater gradient preheating chain.

[0008] Preferably, the turbine body includes a high-pressure cylinder section, an intermediate-pressure cylinder section, and a low-pressure cylinder section; The M radial steam inlets include at least two of the following: a first radial steam inlet located in the high-pressure cylinder section; a second radial steam inlet located in the intermediate-pressure cylinder section or the transition area between the high-pressure and low-pressure cylinder sections; a third radial steam inlet located at the front end of the low-pressure cylinder section; and a fourth radial steam inlet located in the middle of the low-pressure cylinder section. High-pressure steam enters through a radial inlet near the high-pressure cylinder section, while lower-pressure steam enters through a radial inlet near the low-pressure cylinder section, in order to achieve a corresponding match between steam parameters and the internal pressure levels of the turbine.

[0009] Preferably, each of the radial steam inlets includes an annular steam collecting chamber, a circumferentially distributed nozzle group, a flow regulating mechanism, and a sealing structure; The annular steam collecting chamber is located circumferentially on the outer wall of the cylinder to ensure uniform circumferential distribution of steam. The circumferentially distributed nozzle group is used to accelerate the steam and guide it to the inlet of the corresponding stage moving blade. The flow regulation mechanism is an independent regulating valve, used to regulate the steam flow of the corresponding radial steam inlet or to close the corresponding radial steam inlet; The sealing structure is located at the connection between the radial steam inlet and the cylinder housing to suppress leakage and cross-contamination between steam at different pressure levels.

[0010] Preferably, a premixing structure is provided between each radial steam inlet and the turbine flow passage, the premixing structure comprising at least one of the following: The gradually narrowing spiral premixing chamber has spiral guide ribs or spiral blades on its inner wall to gradually convert the radially entering steam into axial flow consistent with the mainstream. The variable angle-of-attack adaptive stator blade cascade has a gradient exit angle set along the blade height direction to reduce the impact loss and mixing loss when the supplementary steam merges with the mainstream steam. The three-dimensional irregular flow channel, optimized by computational fluid dynamics, is used to improve the flow field uniformity and total pressure recovery coefficient in the steam injection area.

[0011] Preferably, the steam pipeline and valve control subsystem includes steam main pipelines at each level that connect each waste heat boiler to the corresponding radial steam inlet, and each level of steam main pipeline is equipped with an electric regulating valve, a check valve, a safety valve and a drain valve; A cross-level interconnection valve is installed between the main steam pipelines of adjacent pressure levels. When the steam production of a certain waste heat boiler is excessive, steam is supplied to the adjacent low-pressure steam pipeline after de-cooling and pressure reduction. A desuperheating and pressure reducing device is installed on the high-pressure steam main pipeline to bypass the high-pressure steam to the low-pressure pipeline or condenser during system start-up, shutdown, or abnormal operating conditions.

[0012] Preferably, the intelligent monitoring and coordinated control subsystem includes a waste heat parameter real-time monitoring module, a boiler steam parameter adjustment module, a turbine multi-inlet coordinated control module, a load optimization allocation module, and a safety protection interlock module; The waste heat parameter real-time monitoring module is used to establish a real-time distribution model of the waste heat temperature gradient in the kiln. The boiler steam parameter adjustment module is used to adjust the feedwater flow rate and flue gas side damper opening according to changes in waste heat parameters. The multi-inlet coordinated control module of the steam turbine is used to adjust the opening of the regulating valves of each radial steam inlet according to the actual parameters and flow of steam at each stage. The load optimization and allocation module is used to allocate the load between each steam inlet according to the power grid load demand and the kiln heat production status. The safety protection interlock module is used to automatically close the corresponding steam inlet valve and start the bypass system under over-temperature, over-pressure or over-speed conditions.

[0013] Preferably, the power generation system further includes a tail-end low-temperature waste heat deep utilization subsystem, which includes at least one of the following: An economizer or feedwater preheater that uses low-temperature flue gas from a waste heat boiler to heat boiler feedwater. A heat recovery utilization device that uses the exhaust heat from the steam turbine condenser to dry and preheat the kiln feed or to supply heat after the grade is improved by a heat pump. Organic Rankine cycle system that uses low-boiling-point organic working fluid for power generation; A flue gas condensation heat recovery device for condensing low-temperature flue gas containing water vapor and recovering latent heat and condensate.

[0014] The multi-stage steam-coupled turbine power generation method based on the kiln waste heat temperature gradient described in any of the above-mentioned methods includes the following steps: S1. Multiple waste heat collection ports are set along the length of the kiln to collect waste heat discharged from different sections of the kiln according to temperature level, and the temperature and flow parameters of each collection port are monitored in real time. S2. The waste heat collected at different temperature levels from each collection port is sent to the corresponding waste heat boiler for heat exchange to generate steam at different pressures and temperature levels. S3. Steam of different pressure and temperature levels is delivered to the corresponding radial steam inlets set at different positions along the axial direction of the steam turbine, so that the steam of each level enters from the steam turbine pressure stage that matches its parameters and participates in expansion and work. S4. Through the intelligent monitoring and coordination control subsystem, the steam generation parameters of each waste heat boiler, the opening degree of each radial steam inlet regulating valve and the turbine load distribution are dynamically coordinated and controlled to maintain the turbine's optimal operating conditions. S5. The mechanical energy output from the steam turbine is transferred to the generator to generate electricity, and the low-temperature waste heat after the waste heat boiler and the exhaust waste heat of the steam turbine are deeply recovered and utilized.

[0015] The technical effects and advantages of this invention are as follows: This invention achieves the tiered utilization of kiln waste heat and multi-stage steam coupling power generation by collecting waste heat in different temperature ranges along the length of the kiln and generating steam at different pressures and temperatures. The steam is then introduced into the corresponding pressure level through multiple radial steam inlets of the steam turbine. At the same time, combined with intelligent coordination control, it can improve the heat source matching, steam utilization efficiency and system operation stability, and reduce the waste of tail heat, thus achieving good energy saving and efficiency improvement effects. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the system module structure of the present invention; Figure 2 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] This invention provides, for example Figures 1-2 The multi-stage steam-coupled turbine power generation system based on the kiln waste heat temperature gradient shown includes: Kiln; The waste heat gradient acquisition subsystem has N waste heat acquisition ports along the length of the kiln, where N≥3. Each waste heat acquisition port corresponds to the waste heat discharge location in different temperature ranges of the kiln, and is used to collect waste heat at different temperature levels in stages. The multi-stage waste heat boiler subsystem includes N waste heat boilers connected one-to-one with N waste heat collection ports. Each waste heat boiler generates steam with different pressures and different temperature levels according to the temperature level of the waste heat it receives. The multi-radial steam inlet coupled steam turbine subsystem includes a steam turbine body. The steam turbine body has M radial steam inlets at different positions along the axial direction, where M≥2. Each radial steam inlet corresponds to a different pressure level inside the steam turbine. Steam of different pressure and temperature levels enters the corresponding pressure level of the steam turbine through the corresponding radial steam inlet and expands to do work in the downstream stages. The generator is connected to the turbine body via a drive system. The intelligent monitoring and coordination control subsystem is used to coordinate and control the steam intake of each waste heat boiler and each radial steam inlet based on the real-time waste heat parameters and steam parameters at each waste heat collection port, so as to achieve coordinated matching between the gradient utilization of waste heat in the kiln and the multi-stage steam intake work of the steam turbine. In this embodiment, the kiln, as a high-temperature continuous thermal equipment, forms a waste heat temperature gradient distributed from high to low along its length during material firing, cooling, and flue gas emission. To improve the efficiency of the graded utilization of waste heat from this temperature gradient, multiple waste heat collection ports are set up corresponding to different temperature sections of the kiln. Each waste heat collection port is connected to a corresponding waste heat boiler through high-temperature resistant pipes, induced draft mechanisms, and valve control components, thereby introducing waste heat from the high-temperature, medium-temperature, and low-temperature sections into different stages of waste heat boilers for heat exchange. Each stage of the waste heat boiler produces a steam medium with matching pressure and temperature parameters according to the temperature level of the incoming waste heat. This ensures that high-grade waste heat preferentially forms high-pressure, high-temperature steam, while medium- and low-grade waste heat forms medium-pressure or low-pressure steam, avoiding the problem of inefficient degradation of high-temperature heat sources in traditional mixed recovery methods. Furthermore, steam with different parameters output from the multi-stage waste heat boiler is transported via independent steam pipelines to different radial steam inlets arranged axially along the turbine body. Each radial steam inlet corresponds to a different pressure stage inside the turbine. High-pressure, high-temperature steam is introduced from the radial steam inlet of the preceding stage, while medium-pressure or low-pressure steam is introduced from the radial steam inlet of the subsequent corresponding pressure stage. This allows steam at each stage to participate in work within an expansion stage adapted to its own thermodynamic parameters. Through this structure, steam with different parameters does not need to be uniformly depressurized or decooled before being concentrated into the turbine. Instead, it can be utilized in a graded and coupled manner according to the work capacity of each section of the turbine, thereby improving the full utilization of steam enthalpy drop and the overall output efficiency of the turbine. The intelligent monitoring and coordinated control subsystem in this embodiment can be composed of an industrial controller, PLC controller, DCS system, or embedded control unit, and is electrically connected to temperature sensors, pressure sensors, and flow sensors at each waste heat collection port, as well as to each waste heat boiler, steam regulating valve, and turbine inlet actuator. During the control process, the intelligent monitoring and coordinated control subsystem collects the waste heat temperature, flow rate, and fluctuation status at different locations in the kiln in real time, and dynamically adjusts the waste heat extraction ratio, boiler heat exchange load, and steam inlet opening at each radial steam inlet based on the pressure, temperature, and flow rate parameters of the steam at the outlet of each waste heat boiler, so as to maintain the matching operation between the steam generation side and the turbine power generation side. When the kiln operating conditions fluctuate or the local waste heat quality changes, the control system can promptly correct the steam distribution relationship at each stage, reduce the probability of turbine operating under unbalanced conditions, and ensure the continuous and stable output of the power generation system. After implementing the above structure, the present invention has at least the following effects: Firstly, by utilizing the temperature gradient of waste heat along the kiln process to collect and convert waste heat in stages, the utilization of waste heat of different heat grades can be significantly improved, and the waste of high-grade heat energy can be reduced. Secondly, through the multi-radial steam inlet coupling turbine structure, steam at different pressures and temperatures can complete efficient expansion and work within the corresponding pressure level, thereby improving the efficiency of steam thermal energy conversion into mechanical energy. Third, by relying on the intelligent monitoring and coordinated control subsystem to make coordinated adjustments to the waste heat side, steam side and power side, the system's adaptability to kiln operating condition fluctuations can be enhanced, and the operational stability and power generation continuity can be improved. Fourth, the overall system can achieve the cascade utilization of waste heat resources and improve power generation efficiency without significantly increasing the complexity of the kiln main body modification, and has good energy-saving and consumption-reducing effects and industrial promotion value.

[0019] Among them, the waste heat collection port includes at least three or more of the following: high temperature section collection port, medium-high temperature section collection port, medium temperature section collection port and medium-low temperature section collection port, which are respectively set in the corresponding positions of the kiln firing zone, the transition area between the firing zone and the cooling zone, the front section of the cooling zone, the middle and rear section of the cooling zone and the kiln tail flue gas area. Each waste heat collection port is equipped with a high-temperature resistant heat collection hood or flue gas collection pipe, and is equipped with a temperature sensor, flow sensor and regulating valve to collect waste heat temperature and flow parameters in real time and adjust the amount of waste heat extracted. In this embodiment, the waste heat collection ports are segmented according to the thermal distribution characteristics along the kiln, including at least three or more of the following: high-temperature section collection port, medium-high temperature section collection port, medium-temperature section collection port, and medium-low temperature section collection port. Specifically, the high-temperature section collection port is preferably located in the area corresponding to the firing zone of the kiln to collect the waste heat flue gas with the highest temperature and heat grade; the medium-high temperature section collection port is preferably located in the transition area between the firing zone and the cooling zone to collect the transitional waste heat with the second highest temperature and relatively obvious fluctuations; the medium-temperature section collection port is preferably located in the front section of the cooling zone to recover the medium-temperature flue gas with stable waste heat utilization value; and the medium-low temperature section collection port is preferably located in the middle and rear sections of the cooling zone or the kiln tail exhaust area to recover the remaining medium-low grade waste heat. Through the above-mentioned zoning arrangement, the waste heat released from different locations of the kiln can be identified and extracted according to temperature level and heat grade, providing a basis for the corresponding heat exchange and graded steam production of subsequent multi-stage waste heat boilers. Furthermore, each waste heat collection port is equipped with a high-temperature resistant heat collection hood or a flue gas collection pipe. Collection ports located in the firing zone and transition area preferably employ a fire-resistant and corrosion-resistant heat collection hood structure to adapt to high-temperature, high-dust, and thermal shock conditions; collection ports located in the cooling zone or kiln tail area preferably employ a flue gas collection pipe structure to facilitate flue gas collection, diversion, and subsequent transportation. Each waste heat collection port is also equipped with a temperature sensor, a flow sensor, and a regulating valve. The temperature sensor is used to monitor the waste heat temperature at the current collection location in real time, the flow sensor is used to detect changes in the waste heat flue gas flow rate, and the regulating valve is used to continuously adjust the waste heat extraction rate based on the detection results. If necessary, each collection port can also be equipped with a pressure detection element or actuator to improve the accuracy and response speed of waste heat collection and regulation. During operation, the control system determines the waste heat gradient distribution along the length of the kiln based on the temperature and flow parameters fed back from each collection port, and adjusts the valve opening of each collection port according to different heat source grades. When the waste heat temperature rises and the flow rate is sufficient in a certain high-temperature section, the output of the corresponding collection port can be increased to provide a higher heat source to the high-parameter waste heat boiler; when a certain section is under low load or experiencing temperature fluctuations, the control system can appropriately reduce the output of that collection port to avoid excessive local heat extraction affecting the kiln's thermal balance. Therefore, each waste heat collection port can not only achieve zoned waste heat collection, but also achieve on-demand adjustment and dynamic matching during system operation, improving the heat source adaptability of waste heat boilers at all levels. By implementing the above structure, waste heat from different locations in the kiln is collected in stages according to temperature gradients. This improves the accuracy of waste heat identification and the effectiveness of heat source classification and utilization, avoiding the degradation of heat energy utilization caused by mixing waste heat of different grades. By configuring high-temperature resistant heat collection hoods or flue gas collection pipes at each collection port, the adaptability to waste heat from different areas can be enhanced, improving the stability of waste heat extraction and the reliability of equipment operation. With the help of a monitoring and regulation unit composed of temperature sensors, flow sensors, and regulating valves, real-time control of waste heat extraction can be achieved, coordinating the waste heat collection process with the actual operating conditions of the kiln and reducing thermal disturbances. It also provides stable and accurate heat source input conditions for subsequent multi-stage waste heat boiler staged heat exchange and multi-parameter steam generation, thereby helping to improve the cascade utilization efficiency and continuous operational stability of the entire power generation system.

[0020] Each waste heat boiler is equipped with an independent feedwater system, steam drum or once-through evaporation system, blowdown device and safety valve. The waste heat boiler that receives waste heat from the high-temperature section is also equipped with a superheater to output high-pressure superheated steam. A feedwater cascade preheating pipeline is installed between each level of waste heat boiler. The higher temperature feedwater discharged from the low temperature waste heat boiler is used as the preheating water for the higher temperature waste heat boiler to form a feedwater gradient preheating chain. In this embodiment, each waste heat boiler constitutes an independent yet coordinated steam generation unit based on the different temperature levels of the waste heat it receives. Each waste heat boiler is independently equipped with a feedwater system, a steam drum or once-through evaporation system, a blowdown device, and a safety valve. The feedwater system continuously supplies boiler feedwater to the corresponding waste heat boiler to meet the required flow rate and pressure. The steam drum or once-through evaporation system completes the steam-water separation or continuous evaporation heat exchange process after the feedwater is heated. The blowdown device periodically or continuously discharges highly concentrated impurity water generated during boiler operation to maintain stable boiler water quality. The safety valve provides pressure relief protection when the internal steam pressure of the boiler abnormally increases, thereby ensuring the safe operation of each waste heat boiler under different heat load conditions. Furthermore, the waste heat boiler receiving high-temperature waste heat is preferably configured as a high-parameter steam generation unit, with a superheater added after its evaporation heat exchange section. After the high-temperature waste heat completes the heating and evaporation of feedwater through the evaporation heating surface, the generated steam continues to enter the superheater to absorb the remaining high-grade heat in the high-temperature flue gas, thereby outputting high-pressure superheated steam. This high-pressure superheated steam can be directly used as the main power source for the turbine's front-stage steam intake, possessing a high enthalpy value and strong work capacity, which is beneficial for improving the turbine's front-stage expansion efficiency. In contrast, waste heat boilers receiving waste heat from medium-high temperature, medium-temperature, or medium-low temperature sections can output medium-pressure steam, low-pressure steam, or saturated steam respectively, depending on the actual heat source grade, to meet the parameter configuration requirements of multi-stage steam coupling. In this embodiment, a feedwater cascade preheating pipeline is also installed between the waste heat boilers at each stage to form a feedwater gradient preheating chain that transfers heat from the low-temperature stage to the high-temperature stage. Specifically, after the low-grade waste heat recovery is completed, the feedwater or high-temperature water discharged from the low-temperature stage waste heat boiler is not directly discharged, but is transported to the adjacent higher-temperature stage waste heat boiler as preheating feedwater; similarly, the higher-temperature feedwater treated by the medium-temperature stage waste heat boiler can be further transported to the even higher-temperature stage waste heat boiler. Through this multi-stage series preheating method, the originally low-temperature makeup water has a higher initial temperature before entering the high-temperature stage waste heat boiler, thereby reducing the consumption of high-temperature heat source in the initial heating stage of feedwater and increasing the utilization ratio of high-grade heat for evaporation and superheating processes. During operation, the control system coordinates and adjusts the feedwater flow rate, feedwater pressure, steam temperature, and flow rate of each independent feedwater system, as well as the distribution ratio in the cascade preheating pipeline, based on the inlet and outlet water temperatures, steam pressures, steam temperatures, and flow rate parameters of each waste heat boiler. When the low-temperature boiler has sufficient heat, its preheating water supply to the boiler at the next higher stage can be increased to enhance the overall feedwater preheating effect. When the heat source of a boiler fluctuates or its steam production demand changes, the control system can adjust the feedwater transfer ratio between stages and the amount of makeup water input for that stage to avoid problems such as insufficient feedwater in local boilers, heat load imbalance, or excessive deviation in steam parameters. Through these methods, each waste heat boiler can not only achieve independent steam production but also achieve the secondary coupling and utilization of heat through the cascade feedwater preheating structure. After implementing the above structure, at least the following effects are achieved: First, each waste heat boiler is equipped with an independent feedwater system, evaporation system, blowdown device, and safety valve, enabling boiler units of different heat source levels to have good independent operation capabilities and safety assurance capabilities, improving the modularity and operational reliability of the system; Second, after adding superheaters to the high-temperature section waste heat boilers, high-grade waste heat can be fully utilized to output high-pressure superheated steam, significantly enhancing the steam's work-capacity and improving the output efficiency of the turbine's front stage; Third, after forming a feedwater gradient preheating chain between waste heat boilers at each level, low-grade waste heat can be preferentially used for feedwater preheating, reducing the use of high-grade heat in inefficient heating processes, thereby improving overall thermal efficiency and steam generation efficiency; Fourth, this structure can enhance the heat connection and operational synergy between waste heat boilers at each level, enabling the entire waste heat power generation system to maintain good stability and energy cascade utilization effects even under fluctuating kiln heat source conditions.

[0021] The turbine body includes a high-pressure cylinder section, an intermediate-pressure cylinder section, and a low-pressure cylinder section. The M radial steam inlets include at least two of the following: a first radial steam inlet located in the high-pressure cylinder section; a second radial steam inlet located in the intermediate-pressure cylinder section or the transition area between the high-pressure and low-pressure cylinder sections; a third radial steam inlet located at the front end of the low-pressure cylinder section; and a fourth radial steam inlet located in the middle of the low-pressure cylinder section. High-pressure steam enters through a radial inlet near the high-pressure cylinder section, while lower-pressure steam enters through a radial inlet near the low-pressure cylinder section, in order to achieve a corresponding match between steam parameters and the internal pressure levels of the turbine. In this embodiment, the turbine body adopts a multi-stage, staged power-operating structure, including at least a high-pressure stage, a medium-pressure stage, and a low-pressure stage arranged sequentially along the steam expansion direction. The high-pressure stage receives the steam with the highest parameters and completes the initial high-enthalpy-drop expansion work. The medium-pressure stage continues the intermediate-stage work on the steam after the initial expansion or the medium-parameter supplementary steam. The low-pressure stage is used for subsequent expansion and recovery of low-parameter steam to release as much residual heat energy as possible. By dividing the turbine body into different pressure-operating stages, the steam can participate in the expansion process within a flow region adapted to its thermodynamic state, providing a segmented basis for multi-stage steam coupling and intake. Furthermore, the M radial steam inlets are axially spaced according to the internal pressure distribution of each cylinder section of the turbine, including at least two of the following: a first radial steam inlet located in the high-pressure cylinder section; a second radial steam inlet located in the intermediate-pressure cylinder section or the transition area between the high-pressure and low-pressure cylinder sections; a third radial steam inlet located at the front end of the low-pressure cylinder section; and a fourth radial steam inlet located in the middle of the low-pressure cylinder section. The first radial steam inlet is primarily used to introduce high-pressure, high-temperature steam generated by the waste heat boiler in the high-temperature section, allowing it to perform work in the high-pressure stage of the turbine. The second radial steam inlet is used to introduce medium-to-high-pressure steam, allowing this steam to participate in subsequent expansion after matching the turbine's flow pressure in the intermediate-pressure region. The third and fourth radial steam inlets are used to introduce lower-pressure steam, respectively, to complete the corresponding supplementary work process in the front or middle of the low-pressure cylinder section. Each radial steam inlet can be equipped with an independent steam inlet pipeline, regulating valve, and sealing guide structure to ensure that steam with different parameters can be stably introduced at predetermined locations. During operation, high-pressure steam preferentially enters the turbine front through the radial inlet closest to the high-pressure section, ensuring its higher enthalpy is fully utilized in the high-pressure stage. Lower-pressure steam, on the other hand, enters through the radial inlet closest to the low-pressure section to avoid reverse disturbances, flow impacts, or efficiency reductions due to pressure mismatch when directly entering the high-pressure area. The control system dynamically selects the appropriate radial inlet and adjusts the opening of each inlet valve based on the real-time pressure, temperature, and flow parameters of each steam stage, enabling thermal matching between steam with different parameters and the corresponding pressure stage within the turbine. For conditions involving kiln heat source fluctuations or changes in steam output at a particular stage, the load on each section of the turbine can be redistributed by closing some radial inlets, reducing the flow rate of individual inlets, or changing the steam injection sequence to maintain stable overall operation. Furthermore, since the high-pressure, medium-pressure, and low-pressure cylinder sections differ in flow capacity, blade structure, and permissible steam inlet parameters, introducing steam of different pressure levels into different cylinder sections or transition regions can reduce the need for centralized pressurization, de-temperatureing, or throttling adaptation of low-parameter steam under the traditional unified main steam inlet method. In other words, steam at each pressure level can directly enter the adapted working region without undergoing transition parameter correction, thereby reducing throttling and mixing losses and improving the efficiency of steam enthalpy drop utilization. Simultaneously, the axial distribution of multiple radial steam inlets enhances the turbine's ability to accept multi-source steam, enabling the turbine to adapt to multi-pressure, multi-temperature steam supply modes formed by waste heat gradient recovery from kilns. After implementing the above structure, at least the following effects are achieved: First, dividing the turbine body into high-pressure, medium-pressure, and low-pressure sections, and setting multiple radial steam inlets along the axial direction, provides corresponding work inlets for steam with different parameters, improving the adaptability of multi-stage steam coupling utilization; Second, high-pressure steam enters from the inlet closer to the high-pressure section, and lower-pressure steam enters from the inlet closer to the low-pressure section, which can effectively reduce the impact loss and efficiency reduction caused by the mismatch between steam parameters and section pressure; Third, steam with different parameters can complete work within their respective suitable expansion stages, which is conducive to improving the overall output power and thermal energy conversion efficiency of the turbine; Fourth, this structure enhances the turbine's adaptability to fluctuating waste heat conditions in kilns and multi-source steam supply conditions, thereby helping to improve the operational stability and continuous power generation capacity of the entire waste heat power generation system.

[0022] Each radial steam inlet includes an annular steam collecting chamber, a circumferentially distributed nozzle group, a flow regulating mechanism, and a sealing structure; The annular steam collector is located on the outer wall of the cylinder in the circumferential direction. It is used to distribute steam evenly in the circumferential direction and is connected to the corresponding stage steam main pipeline. It is used to collect and distribute the steam entering the radial steam inlet in the circumferential direction, so that the steam forms a relatively uniform pressure field and flow field in the circumferential direction before entering the steam turbine flow passage. This avoids the steam from entering only from a local position, which may cause flow deviation, local impact or uneven blade stress. The annular steam collector can adopt a segmented shell structure or an integral annular cavity structure, and is equipped with pressure-resistant, heat-resistant and thermal fatigue-resistant materials according to the corresponding steam inlet pressure level to meet the stable operation requirements under long-term alternating conditions. The circumferentially distributed nozzle group is used to accelerate steam and guide it to the inlet of the corresponding stage moving blade. The circumferentially distributed nozzle group is located between the annular steam collector and the corresponding stage flow area of ​​the turbine, with multiple nozzles evenly arranged circumferentially. The function of the nozzle group is to convert the relatively stable steam in the annular steam collector into jet steam with a certain velocity direction and flow kinetic energy, and guide it into the inlet area of ​​the corresponding stage moving blade at a predetermined angle. By uniformly arranging the nozzle group circumferentially, a more balanced steam distribution in the circumferential direction can be achieved, reducing the risk of additional vibration, blade eccentricity, and airflow separation caused by excessive local flow. For steam of different pressure levels, the nozzle throat size, injection angle, and outlet cross-sectional shape can be differentiated, so that steam with different parameters can obtain an inlet state adapted to the corresponding stage blade. The flow regulation mechanism consists of independent regulating valves used to adjust the steam flow rate at the corresponding radial steam inlet or to close the corresponding radial steam inlet. Preferably, the flow regulation mechanism uses independent regulating valves, installed on the steam branch corresponding to each radial steam inlet, to regulate the steam flow rate at that radial steam inlet or to close the corresponding radial steam inlet under specific operating conditions. The control system can individually control each independent regulating valve based on changes in kiln waste heat, fluctuations in steam production from the waste heat boiler, and the load distribution of each cylinder section of the turbine, thereby achieving on-demand distribution of steam with different parameters. When the steam production of a certain stage is insufficient, the opening of the corresponding inlet can be appropriately reduced to prevent low-parameter steam from forcibly entering the mismatched stage section; when the steam supply of a certain stage is sufficient, the opening of the corresponding valve can be increased to enhance the supplementary steam's work capacity for that stage. Thus, each radial steam inlet can form a flexible steam inlet regulation system under unified and coordinated control, improving the turbine's adaptability to multi-source steam. The sealing structure is located at the connection between the radial steam inlet and the cylinder shell to suppress leakage and cascading between steam at different pressure levels. This prevents uncontrolled release of high-pressure steam into adjacent low-pressure areas, or steam from low-pressure areas flowing back into high-pressure areas and disrupting normal flow. The sealing structure can employ labyrinth seals, elastic sealing rings, segmented combined heat-resistant seals, or combinations thereof, to balance sealing reliability and thermal expansion adaptability under high-temperature steam environments. By installing sealing structures at the connection areas of each radial steam inlet, internal bypass leakage losses can be effectively reduced, maintaining the relative stability of the flow boundaries at each pressure level, thereby ensuring the controllability of the internal thermodynamic processes of the turbine under multi-stage supplementary steam conditions.

[0023] A premixing structure is installed between each radial steam inlet and the turbine flow path. This premixing structure pre-processes the velocity direction, flow uniformity, and local turbulence of the incoming steam, ensuring that the incoming steam forms a flow state as compatible as possible with the mainstream direction, velocity distribution, and pressure gradient before entering the main flow region. This reduces impact losses, eddy current losses, and mixing losses caused by direct steam convergence, and improves the conversion efficiency of incoming steam energy into effective work. The premixing structure includes at least one of the following: A converging helical premixing chamber, with helical guide ribs or blades on its inner wall, gradually transforms radially entering steam into axial flow aligned with the mainstream. This premixing chamber is located between the end of the radial steam inlet and the main turbine flow channel. The helical guide ribs or blades on its inner wall cause the steam, initially entering radially, to gradually change its flow direction as it passes through the premixing chamber. Under the constraint of the converging flow channel, it gradually transforms into axial or quasi-axial flow aligned with the turbine's mainstream. Through the combined effect of helical guidance and converging acceleration, the lateral velocity component when supplementary steam suddenly enters the mainstream is reduced, mitigating localized impacts and flow field distortion caused by abrupt changes in flow direction, and improving the smoothness of the supplementary steam flow before entering the turbine blades. The variable angle-of-attack adaptive stator blade cascade features a gradient exit angle along the blade height direction to reduce impact and mixing losses when makeup steam merges with mainstream steam. This gradient exit angle adapts to the radial distribution variations of makeup steam flow rate, pressure, and velocity, ensuring that makeup steam at different blade heights can merge with the mainstream at a more reasonable inflow angle. In other words, by changing the guide angle of the stator blade cascade at different blade heights, the makeup steam stream can be stratified and its angle of attack corrected, reducing boundary layer separation, local energy dissipation, and secondary flow enhancement caused by mismatched incident angles when makeup steam merges with mainstream steam, thereby improving the flow field consistency before the steam enters the corresponding moving blade. A three-dimensional irregular flow channel, optimized through computational fluid dynamics, is used to improve the flow field uniformity and total pressure recovery coefficient in the steam injection region. This 3D irregular flow channel is numerically simulated and optimized based on the steam injection inlet conditions, mainstream channel geometry, and target confluence state, enabling the steam injection to achieve velocity redistribution, pressure balance, and flow direction adjustment within a limited space. By optimizing the channel cross-sectional shape, bending transition radius, and local diffusion or contraction, the flow field uniformity and total pressure recovery coefficient in the steam injection region can be improved, reducing the formation of local vortex regions and high dissipation regions. This structure is particularly suitable for applications with significant variations in operating conditions and large fluctuations in steam injection parameters, helping to improve the flow stability of the turbine during variable load operation.

[0024] The steam pipeline and valve control subsystem includes steam main pipelines at each level that connect each waste heat boiler to its corresponding radial steam inlet. Each level of steam main pipeline is equipped with an electric regulating valve, a check valve, a safety valve, and a drain valve. A cross-level connecting valve is installed between adjacent pressure level steam main pipelines. When a waste heat boiler produces excess steam, it will supply steam to the adjacent low-pressure steam main pipeline after desuperheating and pressure reduction. A desuperheating and pressure reduction device is installed on the high-pressure steam main pipeline to bypass the high-pressure steam to the low-pressure pipeline or condenser during system start-up, shutdown, or abnormal operating conditions. In this embodiment, the steam pipeline and valve control subsystem is used to achieve stable delivery, parameter adjustment, and safety protection of steam produced by each waste heat boiler to the corresponding radial steam inlet of the turbine. This steam pipeline and valve control subsystem includes steam main pipelines at each level, connecting each waste heat boiler to its corresponding radial steam inlet. Each steam main pipeline is independently configured according to steam pressure and temperature levels to avoid uncontrolled mixing of steam with different parameters during delivery. Each steam main pipeline is equipped with an electric regulating valve, a check valve, a safety valve, and a drain valve. The electric regulating valve is used to adjust the steam flow rate of the main pipeline according to the control system instructions; the check valve is used to prevent backflow of steam on the turbine side or in other pipelines; the safety valve is used to release overpressure when the pipeline pressure rises abnormally; and the drain valve is used to promptly remove condensate generated during steam delivery to reduce the risk of water hammer and maintain steam dryness and delivery stability. Furthermore, the main steam pipelines at all levels are preferably made of high-temperature and pressure-resistant pipe materials, and corresponding insulation layers and expansion compensation structures are set according to the steam parameters to reduce heat loss and thermal stress during transportation. For high-pressure and high-temperature steam pipelines, higher-grade pressure-resistant pipe fittings, corrugated compensators, or sliding supports can be preferred to accommodate pipeline expansion and deformation caused by steam temperature rise and fall; for medium-pressure or low-pressure steam pipelines, the pipe diameter and support form can be appropriately optimized according to the steam parameters to balance transportation efficiency and system layout compactness. Pressure sensors, temperature sensors, and flow detection elements can also be installed between each main steam pipeline and the corresponding radial steam inlet to enable the control system to obtain the pipeline operating status in real time and implement fine adjustments. In this embodiment, a cross-stage interconnection valve is installed between the main steam pipelines of adjacent pressure levels to form a flexible interconnection channel between adjacent steam levels. When a waste heat boiler produces excess steam that cannot be fully absorbed by the corresponding radial steam inlet, the control system can open the cross-stage interconnection valve between the main steam pipelines of adjacent pressure levels, allowing the excess steam to be de-cooled and depressurized before being supplied to the adjacent low-pressure steam pipeline. In other words, the excess steam that originally belonged to a higher pressure level can be transferred to the lower pressure level steam system to continue participating in subsequent work after parameter adjustment, thereby avoiding energy loss caused by direct steam venting. Through the setting of the cross-stage interconnection valve, the system can realize the redistribution of steam resources between adjacent levels when there is an imbalance in steam production from multiple waste heat boilers, fluctuations in local heat sources in the kiln, or changes in the load distribution of each stage of the steam turbine, thereby improving the flexibility of steam utilization. Furthermore, a desuperheating and pressure-reducing device is installed on the high-pressure steam main pipeline. This device is used to cool and reduce the pressure of high-pressure steam during system start-up and shutdown, sudden changes in steam parameters, partial closure of the turbine inlet, or other abnormal operating conditions, and then bypass the treated steam to the low-pressure pipeline or condenser. Specifically, during system startup, when the turbine has not yet reached the allowable steam inlet conditions, the high-pressure waste heat boiler may have already started producing steam. At this time, the desuperheating and pressure-reducing device can be used to guide the high-pressure steam into the low-pressure pipeline preheating system or discharge it into the condenser, preventing high-pressure steam from accumulating directly in the main pipeline and causing overpressure. In the event of an abnormal system shutdown or temporary closure of a high-pressure radial steam inlet, this device can also be used to release or transfer high-pressure steam in a timely manner, preventing the high-pressure steam from being unable to be absorbed and causing impact on the boiler and pipeline. Thus, the desuperheating and pressure-reducing device not only has an emergency release function, but also has start-up and shutdown buffering and steam reuse regulation functions. During operation, the intelligent monitoring and coordinated control subsystem controls the opening of the electric regulating valves on each main steam pipeline based on the pressure, temperature, and flow rate of the steam at the outlet of each waste heat boiler and the real-time demand of each radial steam inlet of the turbine. This ensures that steam with different parameters preferentially enters the matching radial steam inlets. When a main steam pipeline experiences pressure increase, excess flow, or a decrease in downstream steam demand, the control system determines whether to open the inter-stage connecting valve to replenish the excess steam to the adjacent low-pressure stage main steam pipeline after desuperheating and pressure reduction. When the system is in a start-stop switching or protection interlock state, the control system activates the desuperheating and pressure reduction device on the high-pressure steam pipeline to bypass and transport some high-pressure steam to the low-pressure pipeline or condenser, maintaining the pressure balance and operational safety of the entire steam system. Simultaneously, the check valves, safety valves, and drain valves on each main pipeline continuously perform unidirectional isolation, overpressure protection, and condensate removal functions, thereby ensuring a stable and reliable steam delivery process.

[0025] The intelligent monitoring and coordinated control subsystem includes a real-time waste heat parameter monitoring module, a boiler steam parameter adjustment module, a turbine multi-inlet coordinated control module, a load optimization allocation module, and a safety protection interlock module. Each module can be integrated into a distributed control system, a PLC control platform, an industrial computer, or an embedded control terminal, and communicates with each waste heat collection port of the kiln, each level of waste heat boiler, each steam main pipeline, each radial steam inlet of the turbine, and the generator load adjustment device, thereby forming a closed-loop control system covering the heat source side, heat exchange side, power side, and protection side. The real-time waste heat parameter monitoring module is used to establish a real-time distribution model of the waste heat temperature gradient in the kiln. This module collects parameters such as temperature, flow rate, pressure, and fluctuation status at each waste heat collection point along the kiln's length to identify the waste heat release in different areas of the kiln in real time. It then combines this data with time-series sampling data to construct a dynamically updated waste heat temperature gradient distribution model. This model not only reflects the current heat distribution characteristics of each section of the kiln but also identifies the trends in heat source intensity changes in high-temperature, medium-temperature, and low-temperature zones, thus providing a data foundation for subsequent boiler feedwater regulation, steam generation control, and turbine steam distribution. This module enables the system to perceive changes in kiln operating conditions in real time, avoiding reliance on fixed empirical parameters for coarse control. The boiler steam parameter regulation module adjusts the feedwater flow rate and flue gas side damper opening based on changes in waste heat parameters. When the real-time waste heat parameter monitoring module identifies an increase in waste heat temperature and flow rate in a certain section, the boiler steam parameter regulation module can correspondingly increase the feedwater flow rate of the corresponding waste heat boiler and adjust the flue gas side damper opening to enhance heat exchange and steam production capacity. When the waste heat temperature in a certain section decreases or fluctuations increase, the feedwater flow rate can be reduced or the damper opening can be appropriately narrowed to prevent problems such as unstable steam parameters, steam-water imbalance, or sudden changes in heat load. For high-temperature waste heat boilers, this module can also be used to control the heat exchange load of the superheater section to ensure that the temperature and pressure of high-pressure superheated steam are within the target range. For medium- and low-temperature waste heat boilers, the focus is on maintaining stable steam pressure and flow balance. Through the implementation of this module, the boiler steam production process can be synchronized with changes in waste heat grade, improving the adaptability and stability of multi-stage steam generation. The multi-inlet coordinated control module for the steam turbine adjusts the opening of the regulating valves at each radial inlet based on the actual parameters and flow rates of steam at each stage. This module receives pressure, temperature, flow rate, speed, and load feedback information from the main steam pipelines at each stage and the turbine inlet section. It determines whether the supply capacity of high-pressure, medium-pressure, and low-pressure steam matches the receiving capacity of each power stage of the turbine, and accordingly controls the valve openings of the corresponding inlets in the first, second, third, and fourth radial inlets. When high-pressure steam is sufficient, the steam flow rate at the upstream radial inlet can be appropriately increased; when there is a surplus of medium- or low-pressure steam in a certain stage, the opening of the downstream radial inlet can be increased to enhance the proportion of supplementary steam for power generation in the low-pressure section; if a steam source is insufficient or the parameters deviate, the flow rate at the corresponding inlet is reduced or the inlet is closed. This module enables the turbine to maintain a better steam distribution state under conditions of parallel supply of multi-source steam, reducing local overload, parameter mismatch, and flow disturbances. The load optimization and allocation module is used to allocate load among various steam inlets based on grid load demand and kiln heat production status. When the external grid load demand increases, the module, considering the current heat production capacity of each section of the kiln and the steam production status of each level of waste heat boiler, prioritizes the use of steam inlets with higher heat grade and stronger work capacity to undertake the increased load task. When the grid load decreases or the local heat source of the kiln weakens, the module reduces the flow rate of some steam inlets according to priority to avoid the system operating in an inefficient range. In other words, this module not only considers the thermal efficiency of the turbine itself but also takes into account the balance between the real-time heat source conditions of the kiln and the power demand on the power generation side, ensuring that high-grade steam is preferentially allocated to the high-efficiency work stage, while low-grade steam participates in supplementary work under appropriate load conditions. This improves the overall load tracking capability and comprehensive energy efficiency of the power generation system. The safety protection interlock module is used to automatically close the corresponding steam inlet valves and activate the bypass system under over-temperature, over-pressure, or over-speed conditions. When the system detects that the steam temperature of a certain stage waste heat boiler exceeds the allowable upper limit, the pressure of the main steam pipeline rises abnormally, the turbine speed exceeds the set safety value, or abnormal vibration or leakage trend occurs near a certain radial steam inlet, the safety protection interlock module immediately sends an interlock control command to the corresponding actuator, automatically closing the relevant radial steam inlet regulating valve, electric regulating valve, or steam branch valve, and simultaneously activating high-pressure steam bypass, desuperheating and pressure reduction release, or diversion to the condenser to prevent the abnormal conditions from spreading to adjacent stages. When necessary, the module can also execute staged shutdown logic or whole-unit protection shutdown logic to ensure the safe operation of the turbine, waste heat boiler, and steam pipeline system. During operation, the waste heat parameter real-time monitoring module first continuously collects and models the waste heat status along the kiln. The boiler steam parameter adjustment module dynamically adjusts the feedwater flow rate and flue gas side damper opening of each stage of the waste heat boiler based on the established waste heat gradient model, keeping the steam output parameters of each stage within a predetermined range. Subsequently, the turbine multi-inlet coordinated control module coordinates the opening of each radial steam inlet according to the actual steam pressure, temperature, and flow rate of each stage, allowing steam with different parameters to enter the corresponding pressure stage to perform work. The load optimization and allocation module then optimizes and adjusts the load of each steam inlet based on the power grid demand and the kiln's heat generation status. Throughout the process, the safety protection interlocking module continuously monitors abnormal states such as over-temperature, over-pressure, and over-speed, and executes rapid interlocking control when protection conditions are triggered. Thus, the entire power generation system can form a fully intelligent and coordinated operation mode from waste heat collection, steam generation control, steam allocation to abnormal protection.

[0026] The power generation system also includes a tail-end low-temperature waste heat deep utilization subsystem. After completing the staged steam generation from the waste heat in the high-temperature, medium-high-temperature, and medium-low-temperature sections of the kiln and the multi-stage power generation of the steam turbine, the power generation system also includes a tail-end low-temperature waste heat deep utilization subsystem. This subsystem is used to further recover and utilize the residual low-grade heat at the rear end of the waste heat boiler and the exhaust heat from the steam turbine, thus forming a cascade utilization structure where high-temperature waste heat is used for steam power generation and low-temperature waste heat is used for secondary heat exchange or auxiliary power generation. The tail-end low-temperature waste heat deep utilization subsystem includes at least one of the following: An economizer or feedwater preheater that utilizes low-temperature flue gas from a waste heat boiler to heat boiler feedwater can introduce the low-temperature flue gas discharged from the waste heat boiler into the economizer heat exchange section or feedwater preheater, allowing the initially low-temperature boiler feedwater to be preheated before entering each stage of the waste heat boiler. In this way, the residual sensible heat in the low-grade flue gas can be preferentially used to raise the initial temperature of the feedwater, reducing the high-grade heat consumed by the main heat exchange section to raise the feedwater temperature, thereby improving the thermal efficiency of each stage of the waste heat boiler. Preferably, the economizer or feedwater preheater can be installed in the tail flue and connected to the aforementioned feedwater cascade preheating chain, so that the low-temperature flue gas waste heat recovery and the boiler feedwater cascade heating process complement each other, further enhancing the heat closed-loop utilization of the entire system. This heat recovery device utilizes the exhaust heat from a steam turbine condenser to dry and preheat the kiln feed, or to enhance its heat quality via a heat pump before supplying heat. Specifically, the hot water or low-temperature heat medium discharged from the condenser cooling side can be transported to a material preheater, drying chamber, or heat exchange equipment in the conveying channel to preheat and dehumidify wet materials, raw materials, or auxiliary raw materials before they enter the kiln, reducing the fuel heat consumed by the kiln body during the heating phase. In scenarios requiring external heat supply or a higher temperature heat source, a heat pump unit can be configured to enhance the low-temperature heat in the condenser exhaust heat to a temperature level suitable for process heating or plant heating before utilization. This structure transforms the steam turbine exhaust heat from a simple heat loss into a reusable heat source, improving the overall energy efficiency of the system. An organic Rankine cycle system that uses low-boiling-point organic working fluids for power generation can utilize low-temperature flue gas from the downstream of a waste heat boiler, condenser exhaust heat, or other low-temperature heat sources to evaporate and heat the low-boiling-point organic working fluid, which then drives an expander or a small steam turbine to generate electricity. The type of low-boiling-point organic working fluid can be selected according to the temperature range of the heat source to achieve good evaporation and cycle efficiency even at lower heat source temperatures. This organic Rankine cycle system can be used as an independent generator set or connected in parallel to the plant's power system to recover low-grade heat that is difficult to utilize effectively in traditional steam cycles. Therefore, waste heat that is originally insufficient to generate high-efficiency steam can still be used for secondary power generation through the organic Rankine cycle, thus broadening the energy conversion path of low-temperature waste heat. A flue gas condensation heat recovery device condenses and recovers latent heat and condensate from low-temperature flue gas containing water vapor. This device cools and condenses the water vapor, causing it to release latent heat and form condensate. The device includes a condensation heat exchanger, a condensate collection unit, and a drain pipe. The condensation heat exchanger transfers the latent heat from the flue gas to makeup water, circulating water, or other process media. The condensate collection unit recovers the liquid water formed during condensation. By simultaneously recovering sensible and latent heat from the flue gas, not only can the exhaust gas temperature be further reduced and the depth of low-temperature waste heat recovery improved, but also reusable condensate resources can be obtained. After appropriate purification, the recovered condensate can be used as boiler makeup water, cooling makeup water, or part of the plant's process water, thus achieving both heat recovery and water resource recovery. During operation, the control system selectively activates or combines one or more of the aforementioned low-temperature waste heat deep utilization devices based on the tail flue gas temperature, condenser exhaust heat load, boiler feedwater temperature requirements, external heating demands, and the operating status of the organic Rankine cycle system. When the tail flue gas temperature still has high sensible heat utilization value, the economizer or feedwater preheater is prioritized to raise the boiler feedwater temperature; when the condenser exhaust heat is stable and the kiln raw materials have a preheating requirement, the condenser exhaust heat is prioritized to the feed drying preheating device; when the total amount of low-temperature heat source is large and has independent power generation requirements, the organic Rankine cycle system can be activated for auxiliary power generation; when the water vapor content in the flue gas is high, the flue gas condensation heat recovery device is activated to recover latent heat and condensate. Through the above-mentioned on-demand scheduling and coordinated operation, the tail low-temperature waste heat deep utilization subsystem and the front-end multi-stage steam power generation system can form a seamless overall energy cascade utilization chain.

[0027] According to any of the above-mentioned multi-stage steam-coupled turbine power generation methods based on the kiln waste heat temperature gradient, the following steps are included: S1. Multiple waste heat collection ports are set along the length of the kiln to collect waste heat discharged from different sections of the kiln according to temperature level, and the temperature and flow parameters of each collection port are monitored in real time. S2. The waste heat collected at different temperature levels from each collection port is sent to the corresponding waste heat boiler for heat exchange to generate steam at different pressures and temperature levels. S3. Steam of different pressure and temperature levels is delivered to the corresponding radial steam inlets set at different positions along the axial direction of the steam turbine, so that the steam of each level enters from the steam turbine pressure stage that matches its parameters and participates in expansion and work. S4. Through the intelligent monitoring and coordination control subsystem, the steam generation parameters of each waste heat boiler, the opening degree of each radial steam inlet regulating valve and the turbine load distribution are dynamically coordinated and controlled to maintain the turbine's optimal operating conditions. S5. The mechanical energy output from the steam turbine is transferred to the generator to generate electricity, and the low-temperature waste heat after the waste heat boiler and the exhaust waste heat of the steam turbine are deeply recovered and utilized.

[0028] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multi-stage steam-coupled turbine power generation system based on the waste heat temperature gradient of a kiln, characterized in that, include: Kiln; The waste heat gradient acquisition subsystem has N waste heat acquisition ports along the length of the kiln, where N≥3. Each waste heat acquisition port corresponds to the waste heat discharge location in different temperature ranges of the kiln, and is used to collect waste heat at different temperature levels in stages. The multi-stage waste heat boiler subsystem includes N waste heat boilers connected one-to-one with the N waste heat collection ports. Each waste heat boiler generates steam with different pressures and different temperature levels according to the temperature level of the received waste heat. A multi-radial steam inlet coupled steam turbine subsystem includes a steam turbine body. The steam turbine body has M radial steam inlets at different positions along the axial direction, where M≥2. Each radial steam inlet corresponds to a different pressure level inside the steam turbine. Steam of different pressure and temperature levels enters the corresponding pressure level of the steam turbine through the corresponding radial steam inlet and expands to do work in each downstream level. The generator is connected to the turbine body via a transmission. The intelligent monitoring and coordination control subsystem is used to coordinate and control the steam intake of each waste heat boiler and each radial steam inlet based on the real-time waste heat parameters and steam parameters at each waste heat collection port, so as to achieve coordinated matching between the gradient utilization of waste heat in the kiln and the multi-stage steam intake work of the steam turbine.

2. The multi-stage steam-coupled turbine power generation system based on the kiln waste heat temperature gradient according to claim 1, characterized in that, The waste heat collection port includes at least three or more of the following: high temperature section collection port, medium-high temperature section collection port, medium temperature section collection port, and medium-low temperature section collection port, which are respectively set in the corresponding positions of the kiln firing zone, the transition area between the firing zone and the cooling zone, the front section of the cooling zone, the middle and rear sections of the cooling zone, and the kiln tail flue gas area. Each of the aforementioned waste heat collection ports is equipped with a high-temperature resistant heat collection hood or flue gas collection pipe, and is equipped with a temperature sensor, flow sensor and regulating valve for real-time collection of waste heat temperature and flow parameters and adjustment of waste heat extraction amount.

3. The multi-stage steam-coupled turbine power generation system based on the kiln waste heat temperature gradient according to claim 1, characterized in that, Each of the aforementioned waste heat boilers is equipped with an independent feedwater system, steam drum or once-through evaporation system, blowdown device and safety valve. Among them, the waste heat boiler that receives waste heat from the high-temperature section is also equipped with a superheater to output high-pressure superheated steam. Feedwater cascade preheating pipelines are installed between waste heat boilers at each level. The higher-temperature feedwater discharged from the low-temperature waste heat boiler is used as the preheating feedwater for the higher-temperature waste heat boiler, thus forming a feedwater gradient preheating chain.

4. The multi-stage steam-coupled turbine power generation system based on the kiln waste heat temperature gradient according to claim 1, characterized in that, The turbine body includes a high-pressure cylinder section, an intermediate-pressure cylinder section, and a low-pressure cylinder section; The M radial steam inlets include at least two of the following: a first radial steam inlet located in the high-pressure cylinder section; a second radial steam inlet located in the intermediate-pressure cylinder section or the transition area between the high-pressure and low-pressure cylinder sections; a third radial steam inlet located at the front end of the low-pressure cylinder section; and a fourth radial steam inlet located in the middle of the low-pressure cylinder section. High-pressure steam enters through a radial inlet near the high-pressure cylinder section, while lower-pressure steam enters through a radial inlet near the low-pressure cylinder section, in order to achieve a corresponding match between steam parameters and the internal pressure levels of the turbine.

5. The multi-stage steam-coupled turbine power generation system based on the kiln waste heat temperature gradient according to claim 1, characterized in that, Each of the radial steam inlets includes an annular steam collecting chamber, a circumferentially distributed nozzle group, a flow regulating mechanism, and a sealing structure; The annular steam collecting chamber is located circumferentially on the outer wall of the cylinder to ensure uniform circumferential distribution of steam. The circumferentially distributed nozzle group is used to accelerate the steam and guide it to the inlet of the corresponding stage moving blade. The flow regulation mechanism is an independent regulating valve, used to regulate the steam flow of the corresponding radial steam inlet or to close the corresponding radial steam inlet; The sealing structure is located at the connection between the radial steam inlet and the cylinder housing to suppress leakage and cross-contamination between steam at different pressure levels.

6. The multi-stage steam-coupled turbine power generation system based on the kiln waste heat temperature gradient according to claim 5, characterized in that, A premixing structure is provided between each radial steam inlet and the turbine flow passage, the premixing structure comprising at least one of the following: The gradually narrowing spiral premixing chamber has spiral guide ribs or spiral blades on its inner wall to gradually convert the radially entering steam into axial flow consistent with the mainstream. The variable angle of attack adaptive stator blade cascade has a gradient exit angle set along the blade height direction to reduce the impact loss and mixing loss when the supplementary steam merges with the mainstream steam. The three-dimensional irregular flow channel, optimized by computational fluid dynamics, is used to improve the flow field uniformity and total pressure recovery coefficient in the steam injection area.

7. The multi-stage steam-coupled turbine power generation system based on the kiln waste heat temperature gradient according to claim 1, characterized in that, The steam pipeline and valve control subsystem includes steam main pipelines at each level that connect each waste heat boiler to the corresponding radial steam inlet. Each level of steam main pipeline is equipped with an electric regulating valve, a check valve, a safety valve, and a steam trap. A cross-level interconnection valve is installed between the main steam pipelines of adjacent pressure levels. When the steam production of a certain waste heat boiler is excessive, steam is supplied to the adjacent low-pressure steam pipeline after de-cooling and pressure reduction. A desuperheating and pressure reducing device is installed on the high-pressure steam main pipeline to bypass the high-pressure steam to the low-pressure pipeline or condenser during system start-up, shutdown, or abnormal operating conditions.

8. The multi-stage steam-coupled turbine power generation system based on the kiln waste heat temperature gradient according to claim 1, characterized in that, The intelligent monitoring and coordinated control subsystem includes a waste heat parameter real-time monitoring module, a boiler steam parameter adjustment module, a turbine multi-inlet coordinated control module, a load optimization allocation module, and a safety protection interlock module. The waste heat parameter real-time monitoring module is used to establish a real-time distribution model of the waste heat temperature gradient in the kiln. The boiler steam parameter adjustment module is used to adjust the feedwater flow rate and flue gas side damper opening according to changes in waste heat parameters. The multi-inlet coordinated control module of the steam turbine is used to adjust the opening of the regulating valves of each radial steam inlet according to the actual parameters and flow of steam at each stage. The load optimization and allocation module is used to allocate the load between each steam inlet according to the power grid load demand and the kiln heat production status. The safety protection interlock module is used to automatically close the corresponding steam inlet valve and start the bypass system under over-temperature, over-pressure or over-speed conditions.

9. The multi-stage steam-coupled turbine power generation system based on the kiln waste heat temperature gradient according to claim 1, characterized in that, The power generation system further includes a tail-end low-temperature waste heat deep utilization subsystem, which includes at least one of the following: An economizer or feedwater preheater that uses low-temperature flue gas from a waste heat boiler to heat boiler feedwater. A heat recovery utilization device that uses the exhaust heat from the steam turbine condenser to dry and preheat the kiln feed or to supply heat after the grade is improved by a heat pump. Organic Rankine cycle system that uses low-boiling-point organic working fluid for power generation; A flue gas condensation heat recovery device for condensing low-temperature flue gas containing water vapor and recovering latent heat and condensate.

10. The multi-stage steam-coupled turbine power generation method based on the kiln waste heat temperature gradient according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Multiple waste heat collection ports are set along the length of the kiln to collect waste heat discharged from different sections of the kiln according to temperature level, and the temperature and flow parameters of each collection port are monitored in real time. S2. The waste heat collected from each collection port at different temperature levels is sent to the corresponding waste heat boiler for heat exchange to generate steam at different pressures and different temperature levels. S3. Steam of different pressure and temperature levels is delivered to the corresponding radial steam inlets set at different positions along the axial direction of the steam turbine, so that the steam of each level enters from the steam turbine pressure stage that matches its parameters and participates in expansion and work. S4. Through the intelligent monitoring and coordination control subsystem, the steam generation parameters of each waste heat boiler, the opening degree of each radial steam inlet regulating valve and the turbine load distribution are dynamically coordinated and controlled to maintain the turbine's optimal operating conditions. S5. The mechanical energy output from the steam turbine is transferred to the generator to generate electricity, and the low-temperature waste heat after the waste heat boiler and the exhaust waste heat of the steam turbine are deeply recovered and utilized.

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