A waste heat power generation system with multi-source waste heat stepwise coupling utilization

Abstract

The utility model discloses a kind of waste heat power generation systems of multi-source waste heat cascade coupling utilization, including cooling machine, induced draft fan, circulating fan, sintering machine boiler, waste heat boiler, turbine system, feedwater system, circulating cooling water system, turbine exhaust heat exchanger, boiler feedwater preheater and sintering raw material dryer, the output end of the turbine exhaust heat exchanger is connected in the superheating section entrance of waste heat boiler;The hot side of the boiler feedwater preheater is in series and arranged on circulating air supply pipeline, the cold side input port of the boiler feedwater preheater is connected in the deaerator outlet of feedwater system, the cold side output port of the boiler feedwater preheater is connected in the economizer entrance of sintering machine boiler or waste heat boiler;The hot air input port of the sintering raw material dryer is connected in parallel on air duct, in this way, using the high-grade waste heat to preheat saturated steam generated by waste heat boiler, make superheated steam temperature promote, and then promote the power generation of turbine system.

Description

Technical Field

[0001] This utility model relates to the field of waste heat power generation technology, and in particular to a waste heat power generation system that utilizes multi-source waste heat in a cascade coupling manner. Background Technology

[0002] The steel industry is one of the largest energy-consuming sectors, and sintering production energy consumption accounts for about 10% of the total energy consumption of steel enterprises, second only to ironmaking. Therefore, energy conservation in the sintering process plays a very important role in the energy conservation efforts of steel enterprises. Generally speaking, in the sintering process, the sensible heat of hot sintered ore and the sensible heat of flue gas from the main sintering flue account for more than 50% of the total energy consumption. Therefore, making the best use of this waste heat resource is an important way to save energy and reduce consumption in sintering.

[0003] In recent years, while ensuring the quality of sintered ore, the steel industry has continuously focused on and emphasized the application and development of energy-saving technologies for sintering, and has achieved remarkable results. In utilizing sintering waste heat resources, low-temperature waste heat power generation technology is mainly adopted. Its advantages not only lie in the ability to recover waste heat, but also in solving the problem of value-added utilization of waste heat steam, bringing significant economic and social benefits.

[0004] Existing technology discloses an adjustable full-circulation air sintering machine cooler waste heat power generation system. This system improves upon the instability and large fluctuations of traditional sintering machine cooler waste heat power generation systems by constructing a multi-point air intake and air circulation system with adjustable flue gas volume and temperature, combined with an adjustable steam parameter waste heat power generation system. Its flue gas circulation system includes a high-temperature air intake hood and pipeline, a medium-temperature zone one / two adjustable air intake hood and pipeline, and a sintering machine cooler sealing system to reduce air leakage and heat loss. The waste heat power generation system relies on a modular boiler in the sintering machine's large flue, a modular dual-pressure waste heat boiler in the cooler, and a steam turbine system to convert flue gas waste heat into electricity, possessing advantages such as high waste heat recovery rate and reduced environmental pollution. However, the aforementioned existing technology still has significant shortcomings in the comprehensiveness and cascade nature of waste heat utilization, for example:

[0005] It only focuses on the waste heat recovery of flue gas from the cooler and the sintering machine, but does not involve the high-grade waste heat of the steam turbine system exhaust (the steam turbine exhaust temperature is usually 350-400℃). This part of the waste heat is discharged after being cooled by the circulating cooling water system, and is not further used to improve the steam quality, resulting in the waste of high-grade energy. Secondly, the medium-grade waste heat of the circulating make-up air pipeline (which transports flue gas at about 130℃ from the tail of the dual-pressure waste heat boiler) is only used for the circulating make-up air of the cooler, and is not further integrated with the boiler feedwater heating needs. This results in the boiler having to consume more flue gas waste heat to heat the ambient temperature feedwater (the softened water output temperature of the chemical water system is about 25℃), which reduces the overall energy utilization efficiency.

[0006] Therefore, a new technical solution needs to be researched to address the above problems. Utility Model Content

[0007] In view of this, the present invention addresses the deficiencies of the existing technology and its main objective is to provide a waste heat power generation system that utilizes multi-source waste heat in a cascade coupling manner. This system recovers the waste heat from the turbine exhaust steam through a steam turbine exhaust heat exchanger and introduces the exhaust steam from the turbine system, which is directly cooled and discharged, into the superheating section inlet of the waste heat boiler. The high-grade waste heat is used to preheat the saturated steam generated by the waste heat boiler, thereby increasing the temperature of the superheated steam and thus improving the power generation capacity of the turbine system.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A multi-source waste heat cascade coupling waste heat power generation system includes a cooler, an induced draft fan, a circulating fan, a sintering machine boiler, a waste heat boiler, a steam turbine system, a feedwater system, and a circulating cooling water system. The sintering machine boiler and waste heat boiler produce steam, and the steam turbine system consumes steam to generate electricity. The steam turbine system, feedwater system, and circulating cooling water system are connected. One side of the waste heat boiler's flue gas outlet is connected to the inlet of the induced draft fan via an induced draft pipe, and the other side of the waste heat boiler's flue gas outlet is connected to the inlet of the circulating fan via a circulating make-up air pipe. The outlets of the induced draft fan and the circulating fan are respectively connected to the cooler. The steam outlet of the waste heat boiler is connected to the steam turbine system.

[0010] It also includes a steam turbine exhaust heat exchanger, a boiler feedwater preheater, and a sintering raw material dryer; the input end of the steam turbine exhaust heat exchanger is connected to the exhaust outlet of the steam turbine system; the output end of the steam turbine exhaust heat exchanger is connected to the superheater inlet of the waste heat boiler; the hot side of the boiler feedwater preheater is connected in series on the circulating air supply pipeline, the cold side inlet of the boiler feedwater preheater is connected to the deaerator outlet of the feedwater system, and the cold side outlet of the boiler feedwater preheater is connected to the economizer inlet of the sintering machine boiler or the waste heat boiler; the hot air inlet of the sintering raw material dryer is connected in parallel to the induced draft pipeline.

[0011] As a preferred embodiment, the condensate outlet of the turbine exhaust heat exchanger is connected to the deaerator inlet of the feedwater system.

[0012] As a preferred embodiment, the condenser outlet of the steam turbine system is connected to the input end of the circulating cooling water system.

[0013] As a preferred embodiment, the output end of the turbine exhaust heat exchanger is connected to the inlet of the superheat section of the waste heat boiler via a connecting pipe, wherein an electric flow regulating valve is installed on the connecting pipe.

[0014] As a preferred embodiment, the outlet of the induced draft fan is connected to the cooler via a first connecting pipe, and the hot air outlet of the sintering raw material dryer is connected to the first connecting pipe via a return pipe.

[0015] As a preferred embodiment, a one-way check valve is installed on the return pipeline and the first connecting pipeline.

[0016] Compared with the prior art, this utility model has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solution, it mainly recovers the waste heat of the turbine exhaust steam through the turbine exhaust heat exchanger, introduces the exhaust steam of the turbine system that is directly cooled and discharged into the superheat section inlet of the waste heat boiler, and uses the high-grade waste heat to preheat the saturated steam generated by the waste heat boiler, thereby increasing the temperature of the superheated steam and thus increasing the power generation of the turbine system.

[0017] Secondly, the hot side of the boiler feedwater preheater is connected in series with the circulating air supply pipeline. The medium-grade waste heat of the circulating air is used to preheat the feedwater temperature to 80-100℃ before it is sent into the sintering machine boiler (or the economizer inlet of the waste heat boiler). This reduces the amount of waste heat from the flue gas required for the boiler economizer to heat the feedwater, while also reducing the heat load on the boiler heating surface and extending the service life of the equipment.

[0018] Another feature is that the sintering raw material dryer uses medium and low temperature flue gas in the induced draft pipe to pre-dry the sintering raw materials, thereby realizing the gradual utilization of energy.

[0019] To more clearly illustrate the structural features and effects of this utility model, the following detailed description of this utility model is provided in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating an embodiment of the present invention.

[0021] Explanation of reference numerals in the attached diagram:

[0022] 1. Cooler 2. Exhaust fan

[0023] 3. Circulating fan 4. Sintering machine boiler

[0024] 5. Waste heat boiler 6. Steam turbine system

[0025] 7. Water supply system 8. Circulating cooling water system

[0026] 9. Steam turbine exhaust heat exchanger; 10. Boiler feedwater preheater

[0027] 11. Sintering raw material dryer 12. Circulating air supply pipeline

[0028] 13. Exhaust duct 14. First connecting pipe

[0029] 15. Return line 16. One-way check valve

[0030] 17. Electric flow regulating valve. Detailed Implementation

[0031] Please refer to Figure 1 As shown, it illustrates the specific structure of an embodiment of the present invention.

[0032] In the description of this utility model, it should be noted that the directional terms such as "up", "down", "front", "back", "left", and "right" indicate the orientation and positional relationship based on the accompanying drawings or the orientation or positional relationship shown when wearing and using the device normally. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this utility model.

[0033] A multi-source waste heat cascade coupling utilization waste heat power generation system includes a cooler 1, an induced draft fan 2, a circulating fan 3, a sintering machine boiler 4, a waste heat boiler 5, a steam turbine system 6, a feedwater system 7, and a circulating cooling water system 8.

[0034] The sintering machine boiler 4 and waste heat boiler 5 are used to produce steam, and the steam turbine system 6 is used to consume steam for power generation; the steam turbine system 6, the feedwater system 7, and the circulating cooling water system 8 are connected; one side of the flue gas outlet of the waste heat boiler 5 is connected to the inlet of the induced draft fan 2 through the induced draft pipe 13, and the other side of the flue gas outlet of the waste heat boiler 5 is connected to the inlet of the circulating fan 3 through the circulating make-up air pipe 12; the outlets of the induced draft fan 2 and the circulating fan 3 are respectively connected to the cooler 1; the steam outlet of the waste heat boiler 5 is connected to the steam turbine system 6;

[0035] It also includes a steam turbine exhaust heat exchanger 9, a boiler feedwater preheater 10, and a sintering raw material dryer 11; the input end of the steam turbine exhaust heat exchanger 9 is connected to the exhaust outlet of the steam turbine system 6; the output end of the steam turbine exhaust heat exchanger 9 is connected to the superheating section inlet of the waste heat boiler 5.

[0036] Preferably, the condensate outlet of the turbine exhaust heat exchanger 9 is connected to the deaerator inlet of the feedwater system 7, realizing complete recovery of the working fluid and full utilization of heat. The water (condensate) condensed from the turbine exhaust steam after releasing heat in the heat exchanger still has a significantly higher temperature than the ambient temperature and is high-quality distilled water. Sending it directly back to the deaerator inlet recovers the sensible heat carried by the condensate, reduces the steam consumption required by the deaerator to heat the feedwater, and further improves the system's thermal efficiency. On the other hand, it realizes closed-loop recovery of the working fluid, greatly reducing the amount of chemical makeup water, saving water resources, and reducing water treatment costs and system operating expenses.

[0037] Preferably, the condenser outlet of the steam turbine system 6 is connected to the input end of the circulating cooling water system 8. Preferably, the output end of the steam turbine exhaust heat exchanger 9 is connected to the superheated section inlet of the waste heat boiler 5 via a connecting pipe, wherein an electric flow regulating valve 17 is installed on the connecting pipe.

[0038] By adding a steam turbine exhaust heat exchanger 9, the exhaust steam (350-400℃) of the steam turbine system 6, which is directly cooled and discharged, is introduced into the superheating section inlet of the waste heat boiler 5 (cooler 1 modular dual-pressure waste heat boiler 5). This high-grade waste heat is used to preheat the saturated steam generated by the waste heat boiler 5, which can increase the temperature of the superheated steam and thus increase the power generation of the steam turbine system 6 (according to the positive correlation between steam turbine power generation efficiency and steam temperature, the power generation can be increased by 3%-5% for every 10℃ increase in steam temperature). At the same time, the dependence of the superheating section of the waste heat boiler 5 on the waste heat of the cooler 1 flue gas is reduced.

[0039] The hot side of the boiler feedwater preheater 10 is connected in series on the circulating air supply pipeline 12. The cold side inlet of the boiler feedwater preheater 10 is connected to the deaerator outlet of the feedwater system 7. The cold side outlet of the boiler feedwater preheater 10 is connected to the economizer inlet of the sintering machine boiler 4 or the waste heat boiler 5. The hot air inlet of the sintering raw material dryer 11 is connected in parallel on the induced draft pipeline 13.

[0040] The hot side of the boiler feedwater preheater 10 is connected in series with the existing circulating air pipeline 12 (transporting medium-grade flue gas at around 130°C), and the cold side is connected to the deaerator outlet of the feedwater system 7 (softened water at around 25°C). The feedwater temperature is preheated to 80-100°C by utilizing the medium-grade waste heat of the circulating air before being sent to the economizer inlet of the sintering machine boiler 4 or the waste heat boiler 5. This can reduce the waste heat of flue gas required for the boiler economizer to heat the feedwater (according to boiler heat balance calculation, for every 10°C increase in feedwater temperature, approximately 2% of the waste heat consumption of flue gas can be reduced).

[0041] Preferably, the outlet of the induced draft fan 2 is connected to the cooler 1 through the first connecting pipe 14, and the hot air outlet of the sintering raw material dryer 11 is connected to the first connecting pipe 14 through the return pipe 15. After heat exchange (used to dry the sintering raw materials), the hot air of the sintering raw material dryer 11 still retains a certain temperature (usually 30-50°C higher than the ambient temperature). If it is directly discharged, this part of the waste heat will be lost. It is connected to the induced draft pipe 13 through the return pipe 15, so that the flue gas after heat exchange re-enters the waste heat boiler 5, the induced draft pipe 13, and the cooler 1 in a full circulation path.

[0042] Preferably, a one-way check valve 16 is provided on the return pipe 15 and the first connecting pipe 14 to prevent the high-temperature flue gas in the exhaust pipe 13 (the flue gas temperature at the inlet of the cooler 1 is about 150-200℃) from flowing back into the sintering raw material dryer 11 (the raw material in the dryer can withstand a temperature of ≤150℃), thus avoiding overheating and deterioration of the raw material.

[0043] In this embodiment, the sintering machine boiler 4 is used to recover the sensible heat of the medium and low temperature flue gas in the large flue at the tail of the sintering machine. Its flue gas side is directly installed on the large flue of the sintering machine, and the flue gas flows directly through the boiler heating surface. Its feedwater side receives low temperature feedwater from the feedwater system 7 (pressurized by the feedwater pump) through a pipeline.

[0044] The saturated steam generated on the steam side is output to the superheated section of the waste heat boiler 5 through the steam pipeline. The flue gas on the flue gas side returns to the main flue after absorbing heat and cooling. After dust removal and desulfurization, it is discharged into the atmosphere by the main exhaust fan. This is existing technology and will not be described in detail here.

[0045] The waste heat boiler 5 is used to recover the sensible heat of the high-temperature flue gas from the cooler 1. It is the main boiler of the system. Its flue gas inlet on the flue gas side is connected to the high-temperature air intake hood and pipeline (not shown in the figure) and the medium-temperature zone one adjustable air intake hood and pipeline (not shown in the figure) on the cooler 1 through a pipeline.

[0046] The feedwater / steam side is used to receive feedwater from feedwater system 7 (entering its economizer and water-cooled walls) and saturated steam from sintering machine boiler 4 (entering its superheater section).

[0047] The system receives heated working fluid from the turbine exhaust heat exchanger 9 (enters its superheated section inlet to raise the main steam temperature); the superheated steam generated on the steam side is transported to the turbine of the turbine system 6 through the main steam pipeline to perform work; the low-temperature flue gas after heat exchange on the flue gas side is discharged from the tail end and divided into two paths: one path is sent to the induced draft fan 2 through the induced draft pipe 13; the other path is sent to the circulating fan 3 through the circulating make-up air pipe 12.

[0048] The steam turbine system 6 is used to convert the thermal energy of steam into mechanical energy, and then drive the generator to convert it into electrical energy.

[0049] Its main inlet on the steam side receives main steam from waste heat boiler 5. The high-pressure extraction or exhaust steam that has done some work in the steam turbine is transported to the steam turbine exhaust heat exchanger 9 through pipeline to recover its high-grade heat energy. The exhaust steam (vacuum state) of the last stage of the steam turbine enters the condenser. The cooling side of the condenser is connected to the circulating cooling water system 8, which uses circulating water to condense the exhaust steam into water.

[0050] The feedwater system 7 is used to treat and supply the pure water required by the boiler, receive condensate from the condenser of the steam turbine system 6, and receive preheated feedwater from the boiler feedwater preheater 10.

[0051] The deoxygenated high-temperature feedwater is delivered to the economizer of sintering machine boiler 4 and the economizer of waste heat boiler 5 via a feedwater pump.

[0052] The circulating cooling water system 8 is used to provide cooling water for the condenser and auxiliary equipment. The cooling water is delivered to the condenser and auxiliary equipment by a circulating water pump.

[0053] The key design feature of this utility model is that it mainly recovers the waste heat of the turbine exhaust steam through the turbine exhaust heat exchanger, introduces the exhaust steam of the turbine system that is directly cooled and discharged into the superheat section inlet of the waste heat boiler, and uses the high-grade waste heat to preheat the saturated steam generated by the waste heat boiler, thereby increasing the temperature of the superheated steam and thus increasing the power generation capacity of the turbine system.

[0054] Secondly, the hot side of the boiler feedwater preheater is connected in series with the circulating air supply pipeline. The medium-grade waste heat of the circulating air is used to preheat the feedwater temperature to 80-100℃ before it is sent into the sintering machine boiler (or the economizer inlet of the waste heat boiler). This reduces the amount of waste heat from the flue gas required for the boiler economizer to heat the feedwater, while also reducing the heat load on the boiler heating surface and extending the service life of the equipment.

[0055] Another feature is that the sintering raw material dryer uses medium and low temperature flue gas in the induced draft pipe to pre-dry the sintering raw materials, thereby realizing the gradual utilization of energy.

[0056] The above description is merely a preferred embodiment of the present utility model and does not constitute any limitation on the technical scope of the present utility model. Therefore, any minor modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present utility model shall still fall within the scope of the technical solution of the present utility model.

Claims

1. A multi-source waste heat cascade coupling utilization waste heat power generation system, comprising a cooler, an induced draft fan, a circulating fan, a sintering machine boiler, a waste heat boiler, a steam turbine system, a feedwater system, and a circulating cooling water system; wherein the sintering machine boiler and the waste heat boiler are used to produce steam, and the steam turbine system is used to consume steam for power generation; the steam turbine system, the feedwater system, and the circulating cooling water system are connected; one side of the flue gas outlet of the waste heat boiler is connected to the inlet of the induced draft fan via an induced draft pipe, and the other side of the flue gas outlet of the waste heat boiler is connected to the inlet of the circulating fan via a circulating make-up air pipe; the outlets of the induced draft fan and the circulating fan are respectively connected to the cooler; the steam outlet of the waste heat boiler is connected to the steam turbine system, characterized in that: It also includes a steam turbine exhaust heat exchanger, a boiler feedwater preheater, and a sintering raw material dryer; the input end of the steam turbine exhaust heat exchanger is connected to the exhaust outlet of the steam turbine system; the output end of the steam turbine exhaust heat exchanger is connected to the superheater inlet of the waste heat boiler; the hot side of the boiler feedwater preheater is connected in series on the circulating air supply pipeline, the cold side inlet of the boiler feedwater preheater is connected to the deaerator outlet of the feedwater system, and the cold side outlet of the boiler feedwater preheater is connected to the economizer inlet of the sintering machine boiler or the waste heat boiler; the hot air inlet of the sintering raw material dryer is connected in parallel to the induced draft pipeline.

2. The waste heat power generation system for multi-source waste heat cascade coupling utilization according to claim 1, characterized in that: The condensate outlet of the turbine exhaust heat exchanger is connected to the deaerator inlet of the feedwater system.

3. The waste heat power generation system for multi-source waste heat cascade coupling utilization according to claim 1, characterized in that: The condenser outlet of the steam turbine system is connected to the input end of the circulating cooling water system.

4. A waste heat power generation system for multi-source waste heat cascade coupling utilization according to claim 1, characterized in that: The output end of the turbine exhaust heat exchanger is connected to the inlet of the superheat section of the waste heat boiler via a connecting pipe, wherein an electric flow regulating valve is installed on the connecting pipe.

5. A waste heat power generation system for multi-source waste heat cascade coupling utilization according to claim 1, characterized in that: The outlet of the induced draft fan is connected to the cooler through a first connecting pipe, and the hot air outlet of the sintering raw material dryer is connected to the first connecting pipe through a return pipe.

6. A waste heat power generation system for multi-source waste heat cascade coupling utilization according to claim 5, characterized in that: A one-way check valve is installed on the return pipeline and the first connecting pipeline.

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