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

Abstract

The present application belongs to the technical field of lime kiln flue gas waste heat utilization, and particularly relates to a steam supply system utilizing low-temperature flue gas waste heat of a TGS lime kiln. The system comprises, in sequence, a TGS lime kiln, an air / coal preheater, an exhaust gas evaporator, a bag-type dust collector, a dust removal fan, a chimney, and a heater. A feedwater pipeline exchanges heat with the heater through an organic Rankine cycle system or an organic Rankine cycle system and a high-temperature heat pump system, and then exchanges heat with the exhaust gas evaporator. The obtained steam is used for assisting in atomization of low-calorific-value blast furnace gas in the TGS lime kiln. The system fully utilizes the relatively high-grade flue gas heat for superheating and more energy-consuming evaporation, improves the heat exchange efficiency and steam production without affecting the normal production of the original TGS lime kiln, and can realize stable regulation and control of steam production and steam quality when the incoming flue gas parameters of the lime kiln are unstable, and prolongs the service life of the equipment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lime kiln flue gas waste heat utilization, and particularly relates to a steam supply system utilizing low-temperature flue gas waste heat of a TGS lime kiln. BACKGROUND

[0002] Lime and its deep processing products are important auxiliary materials for industrial production, and are widely used in many industries such as metallurgy, chemical industry, environmental protection and the like. Based on the development of the metallurgical lime industry, various furnace kiln technologies have emerged, including rotary kiln, double-furnace vertical kiln, sleeve vertical kiln, beam kiln, coke vertical kiln, TGS lime kiln (low calorific value blast furnace gas center burner kiln) and the like. Among them, the TGS lime kiln has been selected by more and more steel plants in recent years due to its advantages of being able to use low calorific value blast furnace gas, strong adaptability to raw materials, low sulfur and low nitrogen oxide emissions (without additional construction of desulfurization and denitrification system, it can reach the ultra-low emission standard) and the like.

[0003] As known, the blast furnace gas has less effective components such as CO and H2, and more invalid components such as N2 in the same heat consumption, and the generated exhaust gas is large in volume. For example, the same is a 600 t / d lime kiln, the flue gas amount of the TGS lime kiln is 48% higher than that of the double-furnace vertical kiln. In addition, although the TGS lime kiln uses the gas and combustion air double preheating technology to utilize the kiln top high-temperature flue gas heat to increase the temperature of the gas and combustion air into the kiln to above 200℃, the heat consumption is significantly reduced. However, it is found in the actual production process that the heat consumption is still significantly higher than that of the double-furnace vertical kiln.

[0004] It is shown in the literature that among the various losses of the TGS lime kiln heat consumption, the largest proportion is the exhaust gas loss (up to about 25%), followed by the pipeline and heat exchanger heat loss (about 5.5%). The existing kiln tail flue gas waste heat utilization process and the recent measured data are as follows: the 290-360℃ kiln top exhaust gas is reduced to below 250℃ after entering the air / gas preheater. From the air / gas preheater outlet to the bag dust collector inlet, due to the lack of pipeline insulation, the flue gas has a temperature drop of about 50℃, so the flue gas temperature at the bag dust collector inlet is about 200℃. After the bag dust collector, the flue gas is discharged into the chimney. Due to the high flue gas temperature at the bag dust collector inlet, the discharge temperature is generally higher than 170℃, which is much higher than the design discharge requirement. In addition, the flue gas outlet temperature of the gas / air heat exchanger is still high, and if no further temperature reduction measures are taken, it is not conducive to the long-term stable operation of the exhaust gas dust collector, and it also increases the energy consumption of the induced draft fan, and even may cause the emission to exceed the standard.

[0005] At present, the stable operation of the equipment is mainly ensured by dissipating heat to the environment. Obviously, this operation mode is contrary to the concept of sustainable development. Therefore, controlling the heat loss of flue gas and heat dissipation loss, improving the utilization mode of low-grade flue gas waste heat of TGS lime kiln tail, and realizing the application of energy can not only significantly reduce the overall heat consumption of the kiln, but also ensure its safe and stable operation.

[0006] In addition, for the calcination system of the TGS lime kiln, due to the slow combustion speed and low flame temperature of the low-calorific-value blast furnace gas used, a large amount of steam is usually purchased to impact the gas flow to assist atomization in order to enhance the mixing efficiency, prevent flameout, insufficient combustion or reduce the center burning problem, but this increases the operation cost of the TGS lime kiln to some extent. At present, although there are many application cases of using low-temperature flue gas heat of industrial kiln to produce hot water in the coal-electricity, chemical, building material and metallurgy industries, and some cases are used for organic Rankine cycle direct power generation, but there are still few cases of using low-grade flue gas to produce steam and related technical solutions, and the technical solution of directly using low-temperature flue gas waste heat of TGS lime kiln to realize self-supply of steam is still blank. Moreover, the production of steam consumes more energy, and the stable supply control is more complex, which also brings great difficulty to the design of the waste heat recovery system. SUMMARY

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

[0008] The present application adopts the following technical solutions:

[0009] A steam supply system using low-temperature flue gas waste heat of TGS lime kiln, comprising a TGS lime kiln body system and a steam supply system, wherein the TGS lime kiln body system comprises, from the exhaust port of the TGS lime kiln, an air / coal preheater, a bag-type dust collector, a dust removal fan and a chimney connected in sequence through a main pipeline; the steam supply system comprises a flue gas evaporator, a heater and a feedwater pipeline, the flue gas evaporator is connected to the main pipeline between the air / coal preheater and the bag-type dust collector through a first branch, the hot side of the heater is connected to the outlet of the chimney, and the feedwater pipeline generates steam through any one of the following schemes:

[0010] A) The feedwater pipeline and the heater are heat exchanged through an organic Rankine cycle system, the heated feedwater continues to be heat exchanged with the flue gas evaporator, and the obtained steam enters the coal gas burner of the TGS lime kiln to assist low-calorific-value blast furnace gas atomization;

[0011] B) the feedwater pipeline comprises a first feedwater pipeline and a second feedwater pipeline, the first feedwater pipeline exchanges heat with the heater through the organic Rankine cycle system and the high-temperature heat pump system, and generates first steam; the second feedwater pipeline exchanges heat with the flue gas evaporator, and generates second steam; the first steam and the second steam are mixed and then enter the coal gas burner of the TGS lime kiln to assist in atomizing low-calorific-value blast furnace gas.

[0012] Preferably, the hot side of the heater can also only connect the main pipeline between the dust removal fan and the chimney 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.

[0013] Preferably, in the scheme A, the organic Rankine cycle system comprises an expander, an ORC condenser and a booster pump connected in sequence from the heater. The organic Rankine cycle medium absorbs heat from the flue gas side of the heater, releases heat to the feedwater pipeline through the ORC condenser, and obtains hot water.

[0014] Preferably, in the scheme B, the organic Rankine cycle system comprises an expander, a high-temperature heat pump system evaporator and a booster pump connected in sequence 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 comprises a compressor, a condenser and a throttle valve connected in sequence from the high-temperature heat pump system evaporator. The organic Rankine cycle medium absorbs heat from the flue gas side of the heater, releases heat to the high-temperature heat pump system through the high-temperature heat pump system evaporator, and the high-temperature heat pump system releases heat to the first feedwater pipeline through the condenser to obtain first steam.

[0015] Preferably, in the scheme A, the expander is also connected to a generator; in the scheme B, the expander is also connected to the compressor for driving the compressor to work.

[0016] Preferably, in the flue gas flow method, a superheater and the flue gas evaporator are arranged in sequence on the first branch. The feedwater absorbs heat in the flue gas evaporator to form saturated steam, and then enters the superheater to absorb heat to form superheated steam.

[0017] Preferably, in the scheme B, the water side outlet of the condenser is also connected to a water vapor compressor, and the expander is connected to the water vapor compressor for driving the water vapor compressor to work. The first steam is compressed by the water vapor compressor to form superheated steam.

[0018] Preferably, an induced draft fan is arranged between the chimney and the heater.

[0019] Preferably, in the scheme A and the scheme B, the generated steam can also enter a low-pressure steam pipeline network for flue gas denitration or equipment cleaning.

[0020] Preferably, a first valve is arranged between the air / coal preheater and the bag filter, and the first branch is connected to the main pipeline at both ends of the first valve, and the inlet section of the first branch is provided with a second valve.

[0021] The present application has the following beneficial effects:

[0022] 1. The present application provides a technical solution for efficiently producing steam from low-grade flue gas, which realizes the cascade and deep utilization of the low-temperature (below 250℃) flue gas energy after the air / coal preheater of the TGS lime kiln. The steam supply system provided by the present application is different from the traditional industrial waste heat boiler system. By decoupling the traditional waste heat boiler, the waste heat of the exhaust gas from the high-temperature section of the TGS is recovered for use in the superheating section and the evaporation section. Considering the low sulfur content and low acid dew point temperature of the flue gas from the TGS lime kiln, the exhaust gas from the tail chimney is circulated to recover the waste heat of the exhaust gas from the low-temperature section after dust removal, which is first used for organic Rankine cycle (ORC) power generation, which is more valuable, and then the energy of the exhaust gas from the cold end of the ORC is recovered for use in the coal saving section (preheating section) for reuse.

[0023] The present application has the following beneficial effects:

[0024] (1) The relatively high-grade flue gas heat is more fully utilized for superheating and more energy-consuming evaporation, which further improves the steam production and increases the heat exchange efficiency of the superheating section and the evaporation section, thereby reducing the equipment size and cost;

[0025] (2) The waste heat of the exhaust gas from the low-temperature section after dust removal of the TGS is recovered for ORC power generation, which can supply power to the lime kiln body, and the overall heat consumption of the lime kiln is greatly reduced;

[0026] (3) The ORC condenser replaces the coal economizer, which increases the design flexibility of the coal economizer. Since the dust removal problem is not considered, high-efficiency heat exchange tubes or compact plate heat exchanger solutions can be used, which greatly reduces the heat exchange area. At the same time, the dust removal facility can be eliminated, reducing the equipment cost. In addition, the heater can be made of special materials to cope with the problem of acid dew point corrosion of the flue gas;

[0027] (4) The exhaust gas temperature of the lime kiln is further reduced, which can be reduced to below 70℃ from the conventional scheme of 150℃.

[0028] 2, The application can realize the stable regulation and control of steam production and steam quality when the lime kiln flue gas parameters are unstable. The ORC cycle is coupled with the 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, and after the work of the high-temperature heat pump compressor, the heat is released to the desalted water in the high-temperature heat pump condenser to produce 120℃ saturated steam, and then the steam pressure and superheat degree are improved by the water vapor compressor, so that the steam supply is realized. At the same time, the high-temperature heat pump compressor and the water vapor compressor can be driven by the ORC expander, without additional power consumption.

[0029] 3, After the steam supply system of the application is put into operation, low-pressure superheated steam can be produced for the fuel pretreatment system of the TGS lime kiln body, the low-calorific-value blast furnace gas fuel is atomized to realize stable combustion, or can be used for SCR denitrification, equipment cleaning (blowing during shutdown for maintenance), etc., greatly reducing the operation cost of purchased steam. It is expected that the total amount of low-pressure steam produced by a single unit per year can exceed 40,000 tons (calculated at 8000h per year), and the direct benefit is very significant.

[0030] 4, The steam supply system of the application not only does not affect the normal production of the original TGS lime kiln, but also ensures the safe and stable operation of the bag-type dust collector and the dust removal fan. After putting into operation, the working pressure of the dust collector at high temperature can be reduced, the energy consumption of the dust removal fan can be reduced, the service life of the equipment can be prolonged, the accident rate and maintenance cost can be reduced, and the indirect benefit is obvious. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a schematic diagram of the existing TGS lime kiln process.

[0032] Figure 2 It is a schematic diagram of the traditional steam supply system using the low-temperature flue gas waste heat of the TGS lime kiln.

[0033] Figure 3 It is a schematic diagram of the steam supply system using the low-temperature flue gas waste heat of the TGS lime kiln under scheme A.

[0034] Figure 4 It is a schematic diagram of the steam supply system using the low-temperature flue gas waste heat of the TGS lime kiln under scheme B.

[0035] Figure 5 It is a schematic diagram of the system structure formed in parallel between the heater and the dust removal fan and the chimney.

[0036] The meanings of the symbols marked in the figure are as follows:

[0037] 10-TGS lime kiln, 11-air / coal preheater, 12-bag-type dust collector, 13-dust removal fan, 14-chimney, 141-induced draft fan;

[0038] 20 - First branch circuit, 21 - Flue gas evaporator, 22 - Superheater;

[0039] 30-Second branch, 31-Heater, 32-Expander, 321-Generator, 33-ORC condenser, 34-Booster pump;

[0040] 41-Evaporator of high-temperature heat pump system; 42-Compressor; 43-Condenser; 44-Throttle valve;

[0041] 50 - Water supply pipeline, 51 - First water supply pipeline, 52 - Second water supply pipeline;

[0042] 60-Steam compressor;

[0043] 71 - First valve, 72 - Second valve. Detailed Implementation

[0044] The technical solution of the present invention will be described in more detail below with reference to the embodiments and accompanying drawings.

[0045] like Figure 1 As shown, the existing TGS lime kiln process flow is as follows: the TGS lime kiln operates under a slight negative pressure of 110,000 Nm at the kiln top. 3 The flue gas at 325℃ enters the air / coal preheater to preheat the air and coal gas, then cools down to 245℃. After being cooled to 190℃ through the main pipeline, it enters the bag filter. After being further cooled in the bag filter, it passes through the dust removal fan and is then sent into the chimney for discharge at an emission temperature of 175℃.

[0046] If the waste heat from the low-temperature flue gas after the air / coal preheater in the TGS lime kiln is to be recovered and used for steam production, the conventional solution can be found in [reference needed]. Figure 2 , is: 110,000 Nm³ at the outlet of the air / coal preheater 3 Flue gas at 245°C flows through a bypass into a water-tube waste heat boiler (flowing sequentially through the superheater, evaporator, and economizer), then cools to 165°C before entering a bag filter. Further cooling occurs in the bag filter before the gas is passed through a dust collector fan and finally discharged through the chimney at 150°C. Simultaneously, demineralized water at 25°C from the demineralized water network flows sequentially through the tubes of the economizer, evaporator, and superheater, absorbing heat from the flue gas outside the tubes to generate 4 tons / hour of superheated steam at 150°C, 0.4 MPa. Two tons / hour of this superheated steam is then sent to the TGS lime kiln body to mix with blast furnace gas, achieving fuel atomization to improve flame propagation speed and prevent flameout. The remaining two tons / hour of superheated steam is sent to a low-pressure steam network for subsequent equipment cleaning.

[0047] Example 1

[0048] Option A: Under normal operating conditions, the steam supply is sufficient, and the expander 32 is used for power generation.

[0049] A steam supply system using low-temperature flue gas waste heat of TGS lime kiln, comprising a TGS lime kiln body system and a steam supply system, wherein the TGS lime kiln body system comprises, in sequence from the exhaust port of the TGS lime kiln 10, an air / coal preheater 11, a bag-type dust collector 12, a dust removal fan 13 and a chimney 14 connected by a main pipeline. The steam supply system comprises a flue gas evaporator 21, a heater 31 and a feedwater pipeline 50.

[0050] The flue gas evaporator 21 is connected to the main pipeline between the air / coal preheater 11 and the bag-type dust collector 12 by a first branch 20, and a first valve 71 is arranged 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, and a second valve 72 is arranged at the inlet section of the first branch 20. The flue gas inlet of the flue gas evaporator 21 is also connected to a superheater 22, and the first branch 20 is arranged in sequence with the second valve 72, the superheater 22 and the flue gas evaporator 21 in terms of flue gas flow. The hot side of the heater 31 is connected to the outlet of the chimney 14 by a second branch 30, and an induced draft fan 141 is arranged between the chimney 14 and the heater 31.

[0051] The feedwater pipeline 50 exchanges heat with the heater 31 through an organic Rankine cycle system, which comprises, in sequence from the heater 31, an expander 32, an ORC condenser 33 and a booster pump 34. When recovering flue gas waste heat, 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 feedwater pipeline 50 through the ORC condenser 33 to obtain hot water. In this embodiment, the expander 32 is also connected to a generator 321 for power generation.

[0052] The heated feedwater continues to exchange heat with the flue gas evaporator 21 to obtain saturated steam, which then enters the superheater 22 to form superheated steam by absorbing heat. The superheated steam enters the coal gas burner of the TGS lime kiln 10 to assist in atomizing the low-calorific-value blast furnace gas.

[0053] According to this embodiment, a typical working condition is as follows:

[0054] 11 million Nm 3The flue gas at 245℃ flows through the first branch 20 into the superheater 22 and the flue gas evaporator 21 in sequence to heat the near-saturated water, and then is cooled to 165℃ to enter the bag-type dust collector 12, and is further cooled in the bag-type dust collector 12, and then is sent into the chimney 14 through the dust removal fan 13, and is discharged at a temperature of 150℃. Subsequently, the flue gas discharged from the chimney 14 is sent into the ORC system heater 31 through the induced draft fan 141, and is cooled to 70℃ after heating the ORC system medium (R1233zd) to be discharged to the atmosphere. For the ORC cycle, the liquid R1233zd at 48℃ and 0.3MPa is changed into 55℃ and 0.6MPa through the booster pump 34, and then flows into the cold side of the heater 31 to be heated by the flue gas to become gaseous at 105℃ and 0.6MPa, and then is expanded in the expander 32 to generate electricity to become the exhaust gas at 80℃ and 0.3MPa, and then the exhaust gas enters the hot side of the ORC condenser 33 to release heat to the feed water to become liquid at 48℃ and 0.3MPa. At the same time, the feed water is heated to become hot water at 65℃ by flowing through the cold side of the ORC condenser 33, and then enters the superheater 22 and the flue gas evaporator 21 to generate 150℃, 0.4MPa, 5 tons / h of superheated steam. Of which, 2 tons / h of superheated steam is sent into the TGS lime kiln 10 body to be mixed with the blast furnace gas to realize the atomization of the fuel, so as to improve the flame propagation speed and prevent the flame from being extinguished. In addition, 3 tons / h of superheated steam is sent to the low-pressure steam pipe network to be used for cleaning the subsequent equipment.

[0055] Example 2

[0056] In the make-up condition, the steam is insufficient, and the expander 32 is connected with the compressor 42 to drive the expander to work.

[0057] A steam supply system utilizing the low-temperature flue gas waste heat of a TGS lime kiln, comprising a TGS lime kiln body system and a steam supply system, wherein the TGS lime kiln body system comprises, from the exhaust port of the TGS lime kiln 10 in sequence through the main pipeline, the air / coal preheater 11, the bag-type dust collector 12, the dust removal fan 13 and the chimney 14. The steam supply system comprises the flue gas evaporator 21, the heater 31 and the feed water pipeline 50.

[0058] The exhaust gas evaporator 21 is connected to the main pipeline between the air / coal preheater 11 and the bag-type dust collector 12 through a first branch 20, a first valve 71 is arranged 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, and a second valve 72 is arranged at the inlet section of the first branch 20. The flue gas inlet of the exhaust gas evaporator 21 is also connected to the superheater 22, and then the flue gas flow method, the first branch 20 is sequentially provided with the second valve 72, the superheater 22 and the exhaust gas evaporator 21. The hot side of the heater 31 is connected to the outlet of the chimney 14 through a second branch 30, and an induced draft fan 141 is further arranged between the chimney 14 and the heater 31.

[0059] The feedwater pipeline 50 includes a first feedwater pipeline 51 and a second feedwater pipeline 52, and the first feedwater pipeline 51 exchanges heat with the heater 31 through an organic Rankine cycle system and a high-temperature heat pump system.

[0060] 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 circulation 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 throttling valve 44 which are sequentially connected in circulation 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.

[0061] When recovering flue gas waste heat, 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, releases heat to the high-temperature heat pump system through the high-temperature heat pump system evaporator 41, releases heat to the first feedwater pipeline 51 through the condenser 43, and obtains superheated first steam after the steam is compressed by the water vapor compressor 60. In this embodiment, the compressor 42 and the water vapor compressor 60 in the high-temperature heat pump system are respectively connected to the expander 32 and driven to work by the expander 32.

[0062] The second feedwater pipeline 52 exchanges heat with the exhaust gas 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 coal gas burner of the TGS lime kiln 10 to assist in atomizing the low-calorific-value blast furnace gas.

[0063] In this embodiment, if excess steam is generated, the part of the steam can enter a low-pressure steam pipeline network for subsequent equipment cleaning.

[0064] According to this embodiment, a typical working condition is as follows (the feedwater is from desalted water in a desalted water pipeline network):

[0065] 100,000 Nm3 / h of air / coal preheater 11 outlet 3 / h, 245℃ flue gas flows through the first branch 20 into the superheater 22 and the flue gas evaporator 21 in turn to heat part of the 25℃ desalted water from the desalted water pipe network, and then to 165℃ to enter the bag-type dust collector 12, and further to be cooled in the bag-type dust collector 12, and then to be sent to the chimney 14 through the dust removal fan 13, and then to be discharged at a temperature of 150℃. Subsequently, the flue gas discharged from the chimney 14 is sent to the ORC system heater 31 through the induced draft fan 141, and the ORC system medium (R1233zd) is heated and then discharged to the atmosphere at a temperature of 70℃. For the ORC cycle, the liquid R1233zd at 45℃ and 0.3MPa is changed into a gas at 52℃ and 0.6MPa through the booster pump 34, and then flows into the cold side of the heater 31 to be heated by the flue gas to become a gas at 95℃ and 0.6MPa, and then does work in the expander 32 to generate electricity and becomes a gas at 70℃ and 0.3MPa, and then the gas enters the hot side of the high-temperature heat pump system evaporator 41 to release heat to the R245fa working medium of the high-temperature heat pump system to become a liquid at 45℃ and 0.3MPa. For the high-temperature heat pump cycle, the R245fa gas at 55℃ and 0.3MPa enters the compressor 42 to be compressed into a high-temperature and high-pressure gas at 140℃ and 2MPa, and then releases heat to the desalted water in the condenser 43 to become a high-temperature and high-pressure liquid at 110℃ and 2MPa, and then enters the throttling valve 44 to become a gas-liquid two-phase after reducing the temperature and pressure, and then enters the high-temperature heat pump system evaporator 41 to absorb heat from the R1233zd to become a gas at 55℃ and 0.3MPa. At the same time, another part of the desalted water at 25℃ from the desalted water pipe network directly becomes saturated steam at 120℃ after absorbing heat from the cold side of the condenser 43, and then enters the water vapor compressor 60 to generate superheated steam at 150℃ and 0.4MPa, which is combined with the superheated steam generated from the cold side outlet of the superheater 22 to generate 5 tons / h of superheated steam at 150℃, 0.4MPa. Among them, 1.8 tons / h of superheated steam is sent to the TGS lime kiln 10 body to mix with blast furnace gas to achieve fuel atomization, so as to improve the flame propagation speed and prevent flameout. In addition, 3.2 tons / h of superheated steam is sent to the low-pressure steam pipe network for subsequent equipment cleaning.

[0066] In this application, the high-temperature heat pump system evaporator 41 and the ORC condenser 33 can be the same condenser device. See Figure 5The heater 31 also has a second setting position, the heater 31 can be connected on the main pipeline 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, the hot side outlet of the heater 31 is connected to the chimney 14 for low-temperature flue gas discharge, and the rest of the heat exchange process remains unchanged; in this scheme, corresponding valves can also be arranged on the main pipeline between the dust removal fan 13 and the chimney 14 and the second branch 30, this part is a conventional technology, and the present application does not make special limitations on this.

[0067] The above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

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

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

3. A steam supply system utilizing the waste heat of low-temperature flue gas from a TGS lime kiln as described in claim 1, characterized in that, In Scheme A, the organic Rankine circulation system includes an expander (32), an ORC condenser (33), and a booster pump (34) that are sequentially connected to the heater (31). The organic Rankine circulation 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. A steam supply system utilizing the waste heat of low-temperature flue gas from a TGS lime kiln as described in claim 1, characterized in that, In Scheme B, the organic Rankine cycle system includes an expander (32), a high-temperature heat pump system evaporator (41), and a booster pump (34) that are sequentially connected 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) that are sequentially connected 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 line (51) through the condenser (43) to obtain the first steam.

5. A steam supply system utilizing the waste heat of low-temperature flue gas from a TGS lime kiln as described in claim 4, characterized in that, In Scheme A, the expander (32) is also connected to the generator (321); in Scheme B, the expander (32) is also connected to the compressor (42) to drive it to do work.

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

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

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

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

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

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