Steam supply system utilizing low-temperature flue gas waste heat of TGS lime kiln

Abstract

The invention belongs to the technical field of lime kiln flue gas waste heat utilization, and particularly relates to a steam supply system utilizing TGS lime kiln low-temperature flue gas waste heat. Comprising a TGS lime kiln, an air / coal preheater, a smoke exhaust evaporator, a bag-type dust remover, a dust removal fan, a chimney and a heater which are sequentially connected, a water supply pipeline exchanges heat with the heater through an organic Rankine cycle system or the organic Rankine cycle system and a high-temperature heat pump system, and then exchanges heat with the smoke exhaust evaporator; the obtained steam is used for assisting atomization of the low-heating-value blast furnace gas in a TGS lime kiln. According to the system, relatively high-grade flue gas heat is fully utilized for overheating and more energy-consuming evaporation, the heat exchange efficiency and the steam yield are improved under the condition that normal production of an original TGS lime kiln is not affected, stable regulation and control of the steam yield and the steam quality can be achieved when incoming flow flue gas parameters of the lime kiln are unstable, and the service life of equipment is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of lime kiln flue gas waste heat utilization, and in particular relates to a steam supply system utilizing the waste heat of low-temperature flue gas from a TGS lime kiln. Background Art

[0002] Lime and its processed products are important auxiliary materials for industrial production and are widely used in a variety of industries, including metallurgy, chemicals, and environmental protection. The development of the metallurgical lime industry has led to the emergence of a variety of kiln technologies, including rotary kilns, double-bore shaft kilns, sleeve shaft kilns, beam kilns, coke shaft kilns, and TGS lime kilns (low-calorific-value blast furnace gas, centrally burned kilns). TGS lime kilns have been increasingly adopted by steel mills in recent years due to their ability to use low-calorific-value blast furnace gas, wide raw material adaptability, and low sulfur and nitrogen oxide emissions (meeting ultra-low emission standards without the need for additional desulfurization and denitrification systems).

[0003] As we all know, blast furnace gas contains low levels of active ingredients like CO and H2, while it contains high levels of inactive ingredients like N2 for the same amount of heat consumed, resulting in a large volume of waste gas. For example, a TGS lime kiln with a capacity of 600 t / d produces 48% more flue gas than a twin-bore shaft kiln. Furthermore, while the TGS lime kiln utilizes dual preheating technology for gas and combustion air, utilizing the heat from the high-temperature flue gas at the kiln top to raise the inlet temperature of the gas and combustion air to over 200°C, significantly reducing heat consumption, actual production has revealed that its heat consumption is still significantly higher than that of a twin-bore shaft kiln.

[0004] Literature indicates that among the various heat losses in a TGS lime kiln, the largest contribution is to flue gas exhaust losses (up to approximately 25%), followed by heat dissipation in pipes and heat exchangers (approximately 5.5%). The existing process for utilizing waste heat from the kiln exhaust gas, as well as recent field data, indicates that flue gas discharged from the kiln top, which is at 290-360°C, is cooled to below 250°C after entering the air / coal preheater. Due to the lack of insulation in the piping from the air / coal preheater outlet to the bag filter inlet, the flue gas experiences a temperature drop of approximately 50°C, resulting in a flue gas temperature of approximately 200°C at the bag filter inlet. After passing through the bag filter, the flue gas enters an elevated chimney for discharge. Due to the relatively high flue gas temperature at the bag filter inlet, the exhaust temperature is typically above 170°C, far exceeding the design emission requirements. In addition, the flue gas outlet temperature of the gas / air heat exchanger is still high. If no further cooling measures are taken, it will not only be detrimental to the long-term stable operation of the exhaust gas dust collector, but will also increase the energy consumption of the induced draft fan and may even cause emissions to exceed the standard.

[0005] Currently, stable equipment operation is primarily ensured by dissipating heat to the environment. Clearly, this approach runs counter to the concept of sustainable development. Therefore, controlling exhaust heat loss and heat dissipation, optimizing the utilization of waste heat from low-grade flue gas at the tail of the TGS lime kiln, and maximizing energy utilization will not only significantly reduce the kiln's overall heat consumption but also ensure safe and stable operation.

[0006] In addition, for TGS lime kiln calcination systems, because the low calorific value blast furnace gas used has a slow combustion rate and low flame temperature, it is usually necessary to purchase a large amount of steam to impact the gas flow to assist in atomization to enhance mixing efficiency, prevent flameout, incomplete combustion, or reduce center burning problems. However, this increases the operating costs of the TGS lime kiln to a certain extent. Although there are currently many application cases in the coal-fired power, chemical, building materials, metallurgical and other industries that use the heat from low-temperature exhaust gases of industrial kilns to produce hot water, and some cases use it for direct power generation using the organic Rankine cycle, there are few reports on cases of using low-grade flue gas to produce steam and related technical solutions. There is still a lack of technical solutions for directly using the waste heat from low-temperature exhaust gases of TGS lime kilns to achieve self-supplied steam. In addition, the production of steam is more energy-consuming, and the stable supply and regulation are more complex, which also brings great difficulties to the design of waste heat recovery systems. Summary of the Invention

[0007] In order to solve the above technical problems, the present invention provides a steam supply system that utilizes the waste heat of low-temperature flue gas from a TGS lime kiln.

[0008] The present invention adopts the following technical solutions: A steam supply system utilizing the waste heat of low-temperature flue gas from a TGS lime kiln comprises a TGS lime kiln main system and a steam supply system. The TGS lime kiln main system comprises an air / coal preheater, a bag dust collector, a dust removal fan, and a chimney, which are sequentially connected through a main pipe from the TGS lime kiln exhaust port. The steam supply system comprises an exhaust evaporator, a heater, and a water supply pipe. The exhaust evaporator is connected to the main pipe between the air / coal preheater and the bag dust collector via a first branch pipe. The hot side of the heater is connected to the chimney outlet. The water supply pipe generates steam using any of the following schemes: A) The feed water pipeline and the heater exchange heat via an organic Rankine cycle system. The heated feed water further exchanges heat with the exhaust gas evaporator to generate steam that enters the gas burner of the TGS lime kiln to assist in atomizing the low calorific value blast furnace gas. B) The water supply pipeline includes a first water supply pipeline and a second water supply pipeline. The first water supply pipeline exchanges heat with the heater via an organic Rankine cycle system and a high-temperature heat pump system to generate a first steam. The second water supply pipeline exchanges heat with the flue gas evaporator to generate a second steam. The first and second steam are mixed and then enter the gas burner of the TGS lime kiln to assist in atomizing the low calorific value blast furnace gas.

[0009] Preferably, the hot side of the heater can also be connected to the main line between the dust removal fan and the chimney only through the second branch to form a parallel connection. At this time, the hot side outlet of the heater is connected to the chimney for low-temperature flue gas discharge.

[0010] Preferably, in the scheme A, the organic Rankine cycle system includes an expander, an ORC condenser and a booster pump which are connected in a circular manner from the heater. The organic Rankine cycle medium absorbs heat from the flue gas side of the heater and releases the heat to the water supply pipeline through the ORC condenser to obtain hot water.

[0011] Preferably, in the scheme B, the organic Rankine cycle system includes an expander, a high-temperature heat pump system evaporator and a booster pump which are sequentially connected in a cycle from the heater; the high-temperature heat pump system is coupled to the organic Rankine cycle system through the high-temperature heat pump system evaporator, and includes a compressor, a condenser and a throttle valve which are sequentially connected in a cycle from the high-temperature heat pump system evaporator; the organic Rankine cycle medium absorbs heat from the flue gas side of the heater and releases the heat to the high-temperature heat pump system through the high-temperature heat pump system evaporator; the high-temperature heat pump system releases the heat to the first water supply pipeline through the condenser to obtain first steam.

[0012] Preferably, in the scheme A, the expander is further connected to a generator; and in the scheme B, the expander is further connected to the compressor to drive it to perform work.

[0013] Preferably, from the flue gas flow method, a superheater and the exhaust gas evaporator are sequentially arranged on the first branch, the feed water absorbs heat in the exhaust gas evaporator to form saturated steam, and then enters the superheater to absorb heat to form superheated steam.

[0014] Preferably, in the scheme B, the water side outlet of the condenser is also connected to a steam compressor, the expander is connected to the steam compressor to drive it to do work, and the first steam is compressed by the steam compressor to form superheated steam.

[0015] Preferably, an induced draft fan is provided between the chimney and the heater.

[0016] Preferably, in the scheme A and the scheme B, the generated steam can also enter the low-pressure steam network for flue gas denitrification or equipment cleaning.

[0017] Preferably, a first valve is provided between the air / coal preheater and the bag filter, the first branch is connected to the main pipe at both ends of the first valve, and a second valve is provided at the inlet section of the first branch.

[0018] The beneficial effects of the present invention are: 1. A creative technical solution for efficiently producing steam from low-grade flue gas has been proposed, achieving cascaded and comprehensive utilization of the low-temperature (below 250°C) flue gas energy after the TGS lime kiln air / coal preheater. The steam supply system provided by this company differs from traditional industrial waste heat boiler systems by decoupling the traditional waste heat boilers and recovering waste heat from the TGS high-temperature flue gas for use in the superheating and evaporation stages. Taking into account the low sulfur content and acid dew point of TGS lime kiln flue gas, the exhaust gas from the tail stack is recycled, recovering waste heat from the low-temperature flue gas after dust removal, which is first used for more valuable Organic Rankine Cycle (ORC) power generation. The exhaust gas energy from the cold end of the ORC is then recovered for reuse in the coal-saving (preheating) stage.

[0019] The beneficial effects are as follows: (1) The relatively high-grade flue gas heat is more fully utilized for superheating and more energy-consuming evaporation, further increasing steam production, while improving the heat exchange efficiency of the superheating section and evaporation section, reducing equipment size and cost; (2) The waste heat from the low-temperature exhaust gas after TGS dust removal is recovered and used for ORC power generation, which can supply power to the lime kiln main equipment, greatly reducing the overall heat consumption of the lime kiln; (3) Using ORC condenser instead of economizer increases the design flexibility of economizer. Since the dust cleaning problem is not considered, high-efficiency heat exchange tubes or compact plate heat exchange solutions can be used, which greatly reduces the heat exchange area. At the same time, dust cleaning facilities can be eliminated, reducing equipment costs. In addition, special materials can be used for heaters to deal with the problem of flue gas acid dew point corrosion; (4) The exhaust gas temperature of the lime kiln is further reduced from 150℃ in the conventional scheme to less than 70℃.

[0020] 2. This application can achieve stable regulation of steam production and quality when the parameters of the lime kiln's incoming flue gas are unstable. By coupling the ORC cycle with a high-temperature heat pump system, the heat released by the hot side of the ORC condenser is absorbed by the cold side of the high-temperature heat pump evaporator. After the high-temperature heat pump compressor performs work, the heat is released to the desalted water in the high-temperature heat pump condenser to produce 120°C saturated steam. The steam pressure and superheat are then increased by the water vapor compressor, thereby achieving steam replenishment. At the same time, the high-temperature heat pump compressor and the water vapor compressor can be driven by the ORC expander without consuming additional electricity.

[0021] 3. Once operational, the steam supply system described in this application will generate low-pressure superheated steam for the fuel pretreatment system of the TGS lime kiln. This atomizes the low-calorific-value blast furnace gas fuel, enabling stable combustion. This steam supply system can also be used for SCR denitrification and equipment cleaning (downtime for maintenance and purging), significantly reducing the operating cost of purchased steam. The annual low-pressure steam production of a single unit is expected to exceed 40,000 tons (based on 8,000 hours of annual operation), representing significant direct benefits.

[0022] 4. The steam supply system proposed in this application not only does not affect the normal production of the existing TGS lime kiln, but also further ensures the safe and stable operation of the bag dust collector and dust removal fan. Once operational, it will reduce the dust collector's operating pressure at high temperatures and the dust removal fan's energy consumption, extending the equipment's service life and reducing accident rates and maintenance costs, resulting in significant indirect benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the existing TGS lime kiln process flow.

[0024] Figure 2 Schematic diagram of a traditional steam supply system that utilizes waste heat from low-temperature flue gas from a TGS lime kiln.

[0025] Figure 3 Schematic diagram of the steam supply system using the waste heat of low-temperature flue gas from the TGS lime kiln under Scheme A.

[0026] Figure 4 Schematic diagram of the steam supply system using the waste heat of low-temperature flue gas from the TGS lime kiln under Scheme B.

[0027] Figure 5 This is a schematic diagram of the system structure in which the heater is connected in parallel with the main pipe between the dust removal fan and the chimney.

[0028] The meanings of the symbols in the figure are as follows: 10-TGS lime kiln, 11-air / coal preheater, 12-bag dust collector, 13-dust removal fan, 14-chimney, 141-induced draft fan; 20-first branch, 21-exhaust evaporator, 22-superheater; 30-second branch, 31-heater, 32-expander, 321-generator, 33-ORC condenser, 34-boosting pump; 41-high temperature heat pump system evaporator, 42-compressor, 43-condenser, 44-throttle valve; 50-water supply pipeline, 51-first water supply pipeline, 52-second water supply pipeline; 60-water vapor compressor; 71-first valve, 72-second valve. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is described in more detail below with reference to the embodiments and drawings.

[0030] like Figure 1 As shown in the figure, the existing TGS lime kiln process is as follows: TGS lime kiln top slightly negative pressure operation 110,000 Nm 3 / h, 325℃ flue gas enters the air / coal preheater to preheat the air and gas and then cools down to 245℃, then cools down to 190℃ through the main pipeline and enters the bag filter, where it is further cooled and then passes through the dust removal fan and is finally discharged into the chimney at a discharge temperature of 175℃.

[0031] If the waste heat of low temperature flue gas after TGS lime kiln air / coal preheater is recovered and used to produce steam, the conventional solution can be found in Figure 2 , is: 110,000 Nm at the outlet of air / coal preheater 3 Flue gas at 245°C / h flows through a bypass channel into the water-tube waste heat boiler (HRSG), where it flows sequentially through the superheater, evaporator, and economizer. It is then cooled to 165°C before entering the baghouse dust collector. Further cooling occurs in the baghouse, followed by a dust removal fan, before being discharged into the chimney at 150°C. Simultaneously, desalinated water at 25°C from the desalted water network flows sequentially through the economizer, evaporator, and superheater tubes, absorbing heat from the flue gas outside the tubes to generate 150°C, 0.4 MPa, and 4 tons / h of superheated steam. Two tons / h of this superheated steam is then fed into the TGS lime kiln, where it mixes with blast furnace gas to atomize the fuel, increasing flame propagation and preventing flameout. Another 2 tons / h of superheated steam is fed to the low-pressure steam network for subsequent equipment cleaning.

[0032] Example 1 Option A: Normal operating conditions, sufficient steam, and the expander 32 is used for power generation.

[0033] A steam supply system utilizing the waste heat of low-temperature flue gas from a TGS lime kiln (TGS) comprises a TGS lime kiln system and a steam supply system. The TGS lime kiln system includes an air / coal preheater 11, a bag filter 12, a dust removal fan 13, and a chimney 14, all connected sequentially via a main pipeline from the exhaust port of the TGS lime kiln 10. The steam supply system includes an exhaust evaporator 21, a heater 31, and a water supply pipeline 50.

[0034] The exhaust evaporator 21 is connected to the main pipeline between the air / coal preheater 11 and the bag-type dust collector 12 through the first branch 20. A first valve 71 is provided between the air / coal preheater 11 and the bag-type dust collector 12. The first branch 20 is connected to the main pipeline at both ends of the first valve 71. The inlet section of the first branch 20 is provided with a second valve 72. The flue gas inlet of the exhaust evaporator 21 is also connected to the superheater 22. According to the flue gas flow method, the first branch 20 is provided with the second valve 72, the superheater 22 and the exhaust evaporator 21 in sequence. The hot side of the heater 31 is connected to the outlet of the chimney 14 through the second branch 30. An induced draft fan 141 is also provided between the chimney 14 and the heater 31.

[0035] Heat exchange occurs between the water supply line 50 and the heater 31 via an organic Rankine cycle (ORC) system. This system includes an expander 32, an ORC condenser 33, and a booster pump 34, all connected in a sequential fashion from the heater 31. To recover flue gas waste heat, the first valve 71 is closed and the second valve 72 is opened. The ORC medium absorbs heat from the flue gas side of the heater 31 and releases it to the water supply line 50 through the ORC condenser 33, producing hot water. In this embodiment, the expander 32 is also connected to a generator 321 for power generation.

[0036] The heated feed water continues to exchange heat with the exhaust gas evaporator 21 to produce saturated steam, which then enters the superheater 22 to absorb heat and form superheated steam. The superheated steam enters the gas burner of the TGS lime kiln 10 to assist in atomizing the low calorific value blast furnace gas.

[0037] According to this embodiment, a typical working condition is: 110,000 Nm at the outlet of air / coal preheater 11 3 / h, 245°C flue gas flows through first branch 20, sequentially entering superheater 22 and exhaust evaporator 21 to heat near-saturated water. The flue gas is then cooled to 165°C before entering bag filter 12. Further cooled in bag filter 12, it passes through dust removal fan 13 and is discharged into chimney 14 at a temperature of 150°C. The flue gas from chimney 14 then passes through induced draft fan 141 and enters ORC system heater 31, heating the ORC system medium (R1233zd) and cooling it to 70°C before being discharged into the atmosphere. In the ORC cycle, liquid R1233zd at 48°C and 0.3 MPa passes through booster pump 34, becoming 55°C and 0.6 MPa. It then flows into the cold side of heater 31, where it is heated by exhaust gas to a gaseous state of 105°C and 0.6 MPa. It then generates electricity in expander 32, becoming exhaust gas at 80°C and 0.3 MPa. The exhaust gas then flows into the hot side of the ORC condenser 33, releasing heat to the feedwater, where it becomes a liquid at 48°C and 0.3 MPa. Simultaneously, the feedwater absorbs heat from the cold side of the ORC condenser 33, becoming hot water at 65°C. The water then enters superheater 22 and exhaust gas evaporator 21, generating superheated steam at 150°C, 0.4 MPa, and 5 tons / hour. Two tons / hour of this superheated steam is then fed into the TGS lime kiln 10, where it mixes with blast furnace gas to atomize the fuel, increasing flame propagation and preventing flameout. Another 3 tons / h of superheated steam is sent to the low-pressure steam network for use in subsequent equipment cleaning.

[0038] Example 2 In the steam supplementation condition, the steam quantity is insufficient, and the expander 32 is connected to the compressor 42 to drive it to perform work.

[0039] A steam supply system utilizing the waste heat of low-temperature flue gas from a TGS lime kiln (TGS) comprises a TGS lime kiln system and a steam supply system. The TGS lime kiln system includes an air / coal preheater 11, a bag filter 12, a dust removal fan 13, and a chimney 14, all connected sequentially via a main pipeline from the exhaust port of the TGS lime kiln 10. The steam supply system includes an exhaust evaporator 21, a heater 31, and a water supply pipeline 50.

[0040] The exhaust evaporator 21 is connected to the main pipeline between the air / coal preheater 11 and the bag-type dust collector 12 through the first branch 20. A first valve 71 is provided between the air / coal preheater 11 and the bag-type dust collector 12. The first branch 20 is connected to the main pipeline at both ends of the first valve 71. The inlet section of the first branch 20 is provided with a second valve 72. The flue gas inlet of the exhaust evaporator 21 is also connected to the superheater 22. According to the flue gas flow method, the first branch 20 is provided with the second valve 72, the superheater 22 and the exhaust evaporator 21 in sequence. The hot side of the heater 31 is connected to the outlet of the chimney 14 through the second branch 30. An induced draft fan 141 is also provided between the chimney 14 and the heater 31.

[0041] The water supply pipeline 50 includes a first water supply pipeline 51 and a second water supply pipeline 52 . The first water supply pipeline 51 and the heater 31 perform heat exchange via an organic Rankine cycle system and a high-temperature heat pump system.

[0042] Specifically, the organic Rankine cycle system includes an expander 32, a high-temperature heat pump system evaporator 41 and a booster pump 34, which are sequentially connected in a loop from the heater 31. The high-temperature heat pump system is coupled to the organic Rankine cycle system through the high-temperature heat pump system evaporator 41, and includes a compressor 42, a condenser 43 and a throttle valve 44, which are sequentially connected in a loop from the high-temperature heat pump system evaporator 41; the water side outlet of the condenser 43 is also connected to a water vapor compressor 60.

[0043] During flue gas waste heat recovery, the first valve 71 is closed and the second valve 72 is opened. The organic Rankine cycle medium absorbs heat from the flue gas side of the heater 31 and releases the heat to the high-temperature heat pump system via the high-temperature heat pump system evaporator 41. The high-temperature heat pump system then releases the heat to the first water supply line 51 via the condenser 43. The resulting steam is compressed by the water vapor compressor 60 to produce superheated first steam. In this embodiment, the compressor 42 and the water vapor compressor 60 in the high-temperature heat pump system are each connected to the expander 32, and are driven by the expander 32 to produce work.

[0044] The second water supply pipe 52 exchanges heat with the exhaust evaporator 21 and then enters the superheater 22 to absorb heat and form superheated second steam; the first steam and the second steam are mixed and then enter the gas burner of the TGS lime kiln 10 to assist in atomizing the low calorific value blast furnace gas.

[0045] In this embodiment, if excess steam is generated, this steam can enter the low-pressure steam network for subsequent cleaning of equipment.

[0046] According to this embodiment, a typical operating condition is as follows (the feed water comes from the desalted water in the desalted water network): 100,000 Nm at the outlet of air / coal preheater 11 3 / h, 245°C flue gas flows through first branch 20, sequentially entering superheater 22 and exhaust evaporator 21, heating a portion of the 25°C desalted water from the desalted water network. The flue gas is then cooled to 165°C before entering baghouse 12, where it is further cooled and passed through dust removal fan 13 before being discharged into chimney 14 at a temperature of 150°C. The flue gas from chimney 14 then passes through induced draft fan 141 and enters ORC system heater 31, heating the ORC system medium (R1233zd) and cooling it to 70°C before being discharged into the atmosphere. For the ORC cycle, liquid R1233zd at 45°C and 0.3 MPa becomes 52°C and 0.6 MPa after passing through the booster pump 34, then flows into the cold side of the heater 31 and is heated by the exhaust gas to a gas state of 95°C and 0.6 MPa. It then works in the expander 32 to generate electricity and becomes exhaust gas at 70°C and 0.3 MPa. The exhaust gas then enters the hot side of the high-temperature heat pump system evaporator 41, releasing heat to the high-temperature heat pump system R245fa working fluid and becomes a liquid state of 45°C and 0.3 MPa. In the high-temperature heat pump cycle, R245fa gas at 55°C and 0.3 MPa enters compressor 42 and is compressed to a high-temperature, high-pressure gas at 140°C and 2 MPa. It then releases heat to the desalted water in condenser 43, becoming a high-temperature, high-pressure liquid at 110°C and 2 MPa. It then enters throttle valve 44, where it is cooled and decompressed, becoming a two-phase gas-liquid phase. It then enters evaporator 41 of the high-temperature heat pump system, absorbing heat from R1233zd and transforming into a gas at 55°C and 0.3 MPa. Simultaneously, another portion of desalted water at 25°C, drawn from the desalted water network, flows through the cold side of condenser 43, absorbing heat and becoming saturated steam at 120°C. It then enters vapor compressor 60, generating superheated steam at 150°C and 0.4 MPa. This steam is then combined with the superheated steam from the cold outlet of superheater 22 to produce 150°C, 0.4 MPa, and 5 tons / h of superheated steam. 1.8 tons / h of superheated steam is then fed into the TGS lime kiln 10, where it mixes with blast furnace gas to atomize the fuel, increasing flame propagation speed and preventing flameout. Another 3.2 tons / h of superheated steam is fed to the low-pressure steam network for subsequent equipment cleaning.

[0047] In this application, the high temperature heat pump system evaporator 41 and the ORC condenser 33 can be the same condenser device. Figure 5 The heater 31 also has a second setting position. The heater 31 can be connected to the main line between the dust removal fan 13 and the chimney 14 through the second branch 30 to form a parallel connection. At this time, the flue gas discharged by the dust removal fan 13 is connected to the hot side inlet of the heater 31, and the hot side outlet of the heater 31 is connected to the chimney 14 for low-temperature flue gas discharge. The rest of the heat exchange process remains unchanged; in this solution, corresponding valves can also be set on the main line between the dust removal fan 13 and the chimney 14 and the second branch 30. This part is conventional technology and this application does not impose any special restrictions on this.

[0048] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A steam supply system utilizing the waste heat of low-temperature flue gas from a TGS lime kiln, characterized in that: The invention comprises a TGS lime kiln main body system and a steam supply system, wherein the TGS lime kiln main body system comprises an air / coal preheater (11), a bag dust collector (12), a dust removal fan (13) and a chimney (14) which are sequentially connected to the exhaust port of the TGS lime kiln (10) through a main pipe; the steam supply system comprises an exhaust gas evaporator (21), a heater (31) and a water supply pipe (50), wherein the exhaust gas evaporator (21) is respectively connected to the main pipe between the air / coal preheater (11) and the bag dust collector (12) through a first branch pipe (20), the hot side of the heater (31) is connected to the outlet of the chimney (14), and the water supply pipe (50) generates steam through any one of the following schemes: A) heat exchange is performed between the water supply pipe (50) and the heater (31) via an organic Rankine cycle system, and the heated water supply continues to exchange heat with the exhaust gas evaporator (21), generating steam which enters the gas burner of the TGS lime kiln (10) to assist in atomization of low calorific value blast furnace gas; B) The water supply pipeline (50) includes a first water supply pipeline (51) and a second water supply pipeline (52); the first water supply pipeline (51) performs heat exchange with the heater (31) through an organic Rankine cycle system and a high-temperature heat pump system to generate a first steam; the second water supply pipeline (52) performs heat exchange with the exhaust gas evaporator (21) to generate a second steam; the first steam and the second steam are mixed and then enter the gas burner of the TGS lime kiln (10) to assist in atomizing the low calorific value blast furnace gas.

2. A steam supply system utilizing waste heat from low-temperature flue gas of a TGS lime kiln according to claim 1, characterized in that: The hot side of the heater (31) can also be connected to the main pipe between the dust removal fan (13) and the chimney (14) only through the second branch (30) to form a parallel connection, and the hot side outlet of the heater (31) is connected to the chimney (14) for low-temperature flue gas discharge.

3. The steam supply system utilizing the waste heat of low-temperature flue gas from a TGS lime kiln according to claim 1, characterized in that: In the scheme A, the organic Rankine cycle system includes an expander (32), an ORC condenser (33) and a booster pump (34) which are sequentially connected in a circular manner from a heater (31). The organic Rankine cycle medium absorbs heat from the flue gas side of the heater (31) and releases the heat to the water supply pipeline (50) through the ORC condenser (33) to obtain hot water.

4. The steam supply system utilizing the waste heat of low-temperature flue gas from a TGS lime kiln according to claim 1, characterized in that: In the scheme B, the organic Rankine cycle system includes an expander (32), a high-temperature heat pump system evaporator (41) and a booster pump (34) which are sequentially connected in a circular manner from the heater (31); the high-temperature heat pump system is coupled to the organic Rankine cycle system through the high-temperature heat pump system evaporator (41), and includes a compressor (42), a condenser (43) and a throttle valve (44) which are sequentially connected in a circular manner from the high-temperature heat pump system evaporator (41); the organic Rankine cycle medium absorbs heat from the flue gas side of the heater (31) and releases the heat to the high-temperature heat pump system through the high-temperature heat pump system evaporator (41); the high-temperature heat pump system releases the heat to the first water supply pipeline (51) through the condenser (43) to obtain the first steam.

5. A steam supply system utilizing waste heat from low-temperature flue gas of a TGS lime kiln as claimed in claim 4, characterized in that: In the solution A, the expander (32) is further connected to the generator (321); in the solution B, the expander (32) is further connected to the compressor (42) for driving it to perform work.

6. The steam supply system utilizing the waste heat of low-temperature flue gas from a TGS lime kiln according to claim 1, characterized in that: According to the flue gas flow method, a superheater (22) and the exhaust gas evaporator (21) are sequentially arranged on the first branch, and the feed water absorbs heat in the exhaust gas evaporator (21) to form saturated steam, and then enters the superheater (22) to absorb heat to form superheated steam.

7. The steam supply system utilizing the waste heat of low-temperature flue gas from a TGS lime kiln according to claim 4, characterized in that: In the scheme B, the water side outlet of the condenser (43) is also connected to the water vapor compressor (60), and the expander (32) is connected to the water vapor compressor (60) to drive it to perform work. The first steam is compressed by the water vapor compressor (60) to form superheated steam.

8. The steam supply system utilizing the waste heat of low-temperature flue gas from a TGS lime kiln according to claim 1, characterized in that: An induced draft fan (141) is provided between the chimney (14) and the heater (31).

9. The steam supply system utilizing the waste heat of low-temperature flue gas from a TGS lime kiln according to claim 1, characterized in that: In the schemes A and B, the generated steam can also enter the low-pressure steam network for flue gas denitrification or equipment cleaning.

10. The steam supply system utilizing the waste heat of low-temperature flue gas from a TGS lime kiln according to claim 1, characterized in that: A first valve (71) is provided between the air / coal preheater (11) and the bag dust collector (12), the first branch (20) is respectively connected to the main pipes at both ends of the first valve (71), and a second valve (72) is provided at the inlet section of the first branch (20).

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