Sintering circular cooler high-temperature area cross circulation waste heat total recovery and zero emission system

Abstract

The invention belongs to the technical field of energy conservation and emission reduction of sintering circular coolers, and particularly relates to a sintering circular cooler high-temperature area cross circulation waste heat total recovery and zero emission system which comprises a circular cooler, a circular cooling air blower, a waste heat boiler, a circulating fan, a steam turbine generator unit, a condenser and a condensate pump. Flue gas is taken from the first section and the second section, exhaust air from the bottoms of the first-section waste heat boiler and the second-section waste heat boiler returns to the second section and the third section through a circulating fan, a flue gas pipe of the third section is connected with an inlet of a first annular cooling air blower of the first section, a flue gas pipe of the fifth section is connected with an inlet of a fourth annular cooling air blower of the fourth section, and flue gas of the fourth section is sent to sintering production after heat exchange. The parameter superheater is connected with a main steam inlet of the steam turbine generator unit, and the low parameter superheater is connected with a steam supplementing opening of the steam turbine generator unit. The system has the advantages that a new waste heat utilization steam and hot water circulation system is constructed by utilizing the steam supplementing and condensing type steam turbine, and zero emission is realized.

Description

Technical Field

[0001] This invention belongs to the field of energy-saving and emission-reduction technology of sintered ring coolers, and particularly relates to a cross-circulation waste heat recovery and zero-emission system for high-temperature zones of sintered ring coolers. Background Technology

[0002] A sintering ring cooler, also known as a sintering ring type cooler, is used to effectively cool the hot sintered ore discharged from the sintering machine. The sintering ring cooler consists of a transmission device, frame assembly, rotating body assembly, sealing device, feed hopper, discharge hopper, exhaust hood at the discharge point, discharge curved rail assembly, horizontal rail assembly, side rail assembly, support roller assembly, air box assembly, and cover assembly. The sintered cake discharged from the sintering machine is crushed by a single-tooth roller and enters the feed hopper. It is then continuously and evenly spread onto the rotary car via a feed chute. The rotary car is driven by the friction wheel of the drive unit, while a blower simultaneously sends cold air into the air box under the car. The cold air enters the hot sintered ore and exchanges heat with it, gradually cooling the sintered ore. When the trolley returns to the unloading area, its wheels begin to descend along the curved track, unloading the cooled hot sinter into the discharge hopper. The plate feeder installed under the discharge chute then transports the cold sinter to the finished product belt conveyor. After unloading, the trolley rises again along the curved track to its reset position, and the next feeding cycle begins. Generally, the cooling zone of a sintering ring cooler is divided into five sections. High-temperature sinter cakes enter from the first section and flow to the fifth section, with the temperature decreasing from high to low. Currently, the waste heat utilization of sintering ring coolers is mostly limited to the first and second sections, with a maximum power generation capacity of 21 kWh / t. A very small number utilize waste heat from the first, second, and third sections, with a maximum power generation capacity of 24 kWh / t.

[0003] Chinese utility model patent application number 202121918362.0 discloses a full-ring cooling waste heat recovery and zero-emission system for a sintering ring cooler, including a sintering ring cooler flue gas system, a high-temperature zone waste heat recovery system, a medium-temperature zone waste heat recovery system, and a low-temperature zone waste heat recovery zero-emission system. The sintering ring cooler flue gas system includes a high-temperature zone flue gas system and a medium-temperature zone flue gas system. The high-temperature zone flue gas system introduces the high-temperature zone flue gas of the sintering ring cooler into the high-temperature zone waste heat recovery system for waste heat recovery, and sends the heat-exchanged high-temperature zone return flue gas back to the high-temperature zone of the sintering ring cooler. The low-temperature zone flue gas system introduces the low-temperature zone flue gas of the sintering ring cooler into the low-temperature zone waste heat recovery system for waste heat recovery, and sends the heat-exchanged low-temperature zone return flue gas back to the low-temperature zone of the sintering ring cooler. This scheme uses two waste heat recovery boilers to recover waste heat in sections one and two, and sections three to five. However, the accompanying single-inlet condensing steam turbines result in low power generation efficiency. The boiler body lacks a hot water heat exchanger. The fifth-section flue gas is connected in parallel with the boiler to the lower part of the third section of the direct-return annular cooler, but the correct location is not provided, leading to an unbalanced airflow. The return air from the fifth section of the annular cooler is not shown; the diagram only indicates that it enters the lower part of the annular cooler after passing through a heat exchanger. Hot air is used for the fifth section's inlet, which cannot guarantee the cooling of the ore. Furthermore, the biggest problem with this system is the lack of theoretical basis for its design. It only describes the system flow, without specifying how to determine the flue gas flow rate and temperature to maintain thermal balance for ore cooling and boiler heat extraction, how to select steam parameters for high efficiency, or how to ensure the final ore cooling of the annular cooler meets standards. Moreover, this system is unsuitable for sintering annular cooler systems under all production volumes and ore temperatures, and it does not provide applicable production volumes and ore temperatures. The purpose of this patent is to solve the problem that in the actual engineering of existing sintering ring cooler waste heat utilization projects, the schemes are basically without theoretical support, the selection of waste heat boiler inlet air volume and temperature and waste heat utilization circulating fan are copied verbatim, and the waste heat recovery rate and exhaust gas emission are not rigorous enough to achieve the expected results.

[0004] In existing projects utilizing waste heat from sintering ring coolers, the solutions lack theoretical support, and the selection of ring cooler blowers is often copied verbatim. The assessment and acceptance of waste heat recovery rate and exhaust emissions are not rigorous. This results in high production costs for enterprises and is inconsistent with national energy conservation and emission reduction policies. Therefore, it is necessary to redesign the waste heat recovery system for sintering ring coolers to ensure that waste heat recovery, ore cooling, and revenue indicators all achieve the expected results after project implementation. Summary of the Invention

[0005] The purpose of this invention is to provide a cross-circulation waste heat recovery and zero-emission system for the high-temperature zone of a sintering ring cooler, overcoming the shortcomings of existing technologies. The ultimate goal is to achieve full waste heat recovery and zero exhaust emissions. Starting from the ore system and waste heat boiler, a new waste heat utilization steam and hot water circulation system is constructed using a supplementary steam condensing turbine, ensuring that the waste heat recovery, ore cooling, and revenue indicators after the project is implemented meet the expected results.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A cross-circulation waste heat recovery and zero-emission system for a high-temperature zone of a sintering annular cooler includes an annular cooler, an annular cooler blower, a waste heat boiler, a circulating fan, a steam turbine generator set, a condenser, and a condensate pump. The annular cooler is a five-section system, with an annular cooler blower installed in each section. A fume hood is installed on the annular cooler, and the top of the fume hood is connected to the waste heat boiler via a duct. The steam outlet of the waste heat boiler is connected to the steam turbine generator set. The condensate from the steam turbine generator set is collected in the condenser and returned to the waste heat boiler via the condensate pump. The waste heat boiler is a two-stage waste heat boiler, with flue gas taken from the first and second stages. In the first and second sections, the exhaust air from the bottom of the waste heat boiler is returned to the second and third sections via circulating fans. The flue gas pipe of the third section is connected to the inlet of the No. 1 annular cooling blower of the first section, and the flue gas pipe of the fifth section is connected to the inlet of the No. 4 annular cooling blower of the fourth section. The flue gas of the fourth section is sent to the sintering production process after heat exchange in a heat exchanger. The steam turbine generator set is a supplementary steam condensing steam turbine generator set. The high-parameter superheater of the waste heat boiler is connected to the main steam inlet of the supplementary steam condensing steam turbine generator set, and the low-parameter superheater of the waste heat boiler is connected to the supplementary steam port of the supplementary steam condensing steam turbine generator set.

[0007] Furthermore, the fume hood is a partition hood, and the five sections are connected by the partition hood to form five relatively isolated spaces. Each section is equipped with a partition valve at the bottom connecting pipe to prevent air leakage between the sections.

[0008] Furthermore, the waste heat boiler is a dual-pressure waste heat boiler.

[0009] Furthermore, the partition cover structure includes a top cover, partition plates, and a movable plate. The lower surface of the top cover is sealed to the upper ends of the two partition plates respectively. The lower ends of the partition plates are connected to the upper ends of the movable plate by hinges. The lower end of the movable plate overlaps the surface of the ore on the annular cooler. The top cover, partition plates, movable plate, and ore form a relatively sealed space.

[0010] Furthermore, the system is equipped with a sintering machine with a utilization coefficient of <1.35, a high feed temperature of <700℃ for the annular cooler, a flue gas temperature of <380℃ for the first stage of the annular cooler, and a flue gas temperature of <250℃ for the third stage of the annular cooler.

[0011] Furthermore, the steam parameters of the waste heat boiler are as follows: high parameter steam pressure 1.7±0.2MPa, steam temperature 360±20℃; low parameter steam pressure 0.45±0.2MPa, steam temperature 200±20℃.

[0012] Compared with the prior art, the beneficial effects of the present invention are: 1) This invention aims to achieve full recovery of waste heat and zero emissions of waste gas. Starting from the heat source mineral system and dual-pressure waste heat boiler, it uses a supplementary steam condensing steam turbine to construct a new waste heat utilization steam and hot water circulation system to utilize waste heat. This ensures that the waste heat recovery, mineral cooling and revenue indicators after the project is implemented reach the expected results, while achieving zero emissions of waste gas from the annular cooler.

[0013] 2) The present invention provides a solution for the complete recovery of waste heat from the annular cooler. The waste heat from the first, second, and third sections can all be used for waste heat power generation, with a power generation index of 26kWh / t-30kWh / t. At the same time, it also adds hot water heat extraction from the fourth and fifth sections, which far exceeds the existing waste heat utilization index. The hot water produced by the waste heat recovery can be used for heating the sintering process mixture, winter heating, seawater desalination, and other processes. 3) This invention is applicable to both new and renovation projects. New projects should refer to the operating data of existing projects, while renovation projects should combine the operating data before the renovation. The optimized process flow of the system can better realize the multi-level and cascade utilization of energy. It solves the problem of balancing the changes in sintering ore type and the fluctuation of sintering processing volume with the waste heat recovery and flue gas treatment system, thereby achieving true "full recovery of waste heat from the annular cooler and zero emissions". Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the process flow of an embodiment of the present invention; Figure 2 This is a schematic diagram of the partition cover structure in an embodiment of the present invention; Figure 3 This is a schematic diagram of the flue gas and air balance design of the annular cooler, waste heat boiler, and steam turbine generator set in an embodiment of the present invention; In the diagram: 1-Ring cooler section 1, 2-Ring cooler section 2, 3-Ring cooler section 3, 4-Ring cooler section 4, 5-Ring cooler section 5, 6-Isolation cover, 7-Ring cooler blower #1, 8-Ring cooler blower #2, 9-Ring cooler blower #3, 10-Ring cooler blower #4, 11-Ring cooler blower #5, 12-Waste heat boiler, 14-Supplemental steam condensing turbine generator set, 15-Condenser, 16-Condensate pump, 17-Heat exchanger, 18-Top cover, 19-Partition plate, 20-Modible plate, 21-Hinge, 22-Circulating fan, 24-Isolation valve. Detailed Implementation

[0015] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0016] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] The components of the embodiments of the invention described and shown in the accompanying drawings can typically be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0018] See Figure 1 This is a schematic diagram of the process flow of a cross-circulation waste heat recovery and zero-emission system in the high-temperature zone of a sintering annular cooler according to the present invention. In a conventional annular cooler system consisting of an annular cooler, an annular cooler blower, a waste heat boiler, a steam turbine generator set, a condenser 15, and a condensate pump 16, the annular cooler is divided into five sections: annular cooler section 1 (1), annular cooler section 2 (2), annular cooler section 3 (3), annular cooler section 4 (4), and annular cooler section 5 (5). Each section has one annular cooler blower, namely, annular cooler blower #1 (7), annular cooler blower #2 (8), and annular cooler blower #3 (8). Blower 9, #4 annular cooler blower 10, and #5 annular cooler blower 11 are equipped with a fume hood. The top of the fume hood is connected to the waste heat boiler 12 via a duct. The steam outlet of the waste heat boiler 12 is connected to the steam turbine generator set. The steam turbine generator set is a supplementary steam condensing steam turbine generator set 14. The condensate of the steam turbine generator set enters the condenser for collection and is returned to the waste heat boiler 12 via a condensate pump. The fume hood is a partition cover 6. The five sections are separated into five relatively isolated spaces by the partition cover. Each section is equipped with a partition valve 24 at the bottom connecting pipe. Waste heat boiler 12 is a two-stage waste heat boiler. The flue gas is taken from the first and second stages. The exhaust air from the bottom of the two-stage waste heat boiler is returned to the second and third stages via circulating fan 22. The flue gas pipe of the third stage is connected to the inlet of the No. 1 annular cooling blower of the first stage. The flue gas pipe of the fifth stage is connected to the inlet of the No. 4 annular cooling blower of the fourth stage. The flue gas of the fourth stage is sent to the sintering production process after heat exchange in the heat exchanger. The high-parameter superheater of waste heat boiler 12 is connected to the main steam inlet of the steam-supplemented condensing steam turbine generator set 14. The low-parameter superheater of waste heat boiler 12 is connected to the steam-supplemented condensing steam turbine generator set 14.

[0019] See Figure 2The partition cover 6 structure includes a top cover 18, partition plates 19 and movable plates 20. The lower surface of the top cover is sealed to the upper ends of the two partition plates 19 respectively. The lower ends of the partition plates 19 are connected to the upper ends of the movable plates 20 by hinges 21. The lower end of the movable plates 20 overlaps the surface of the ore on the ring cooler. The top cover 18, partition plates 19, movable plates 20 and ore form a relatively sealed space, which effectively prevents air leakage between sections and heat loss.

[0020] Waste heat boiler 12 is a dual-pressure waste heat boiler. The steam parameters are: high-parameter steam pressure 1.7±0.2MPa, steam temperature 360±20℃; low-parameter steam pressure 0.45±0.2MPa, steam temperature 200±20℃. The high-parameter steam ensures power generation efficiency, while the low-parameter steam ensures heat extraction and reduces flue gas temperature. The return air from the annular cooler ensures cooling of the feedstock. Excessively high high-parameter steam pressure will reduce evaporation, while excessively low pressure will reduce turbine power generation efficiency. The steam temperature must be set reasonably based on the upper limit of flue gas temperature; too high a temperature will not guarantee a reasonable steam temperature under low-load conditions, while too low a temperature will reduce the power generation efficiency of waste heat utilization.

[0021] In this embodiment of the invention, the sintering machine utilization coefficient is <1.35, the feed temperature of the annular cooler is relatively high (<700℃), the flue gas temperature of the first stage of the annular cooler is <380℃, and the flue gas temperature of the third stage of the annular cooler is <250℃. See [link / reference] Figure 3 The total amount of ore processed by the annular cooler is calculated based on the sintering machine area, sintering machine utilization coefficient, and total return material coefficient of the sintering machine. The reasonable cooling air volume for each section is calculated based on the ore volume and temperature of the annular cooler to meet the cooling requirements. The ratio of hot water and steam is calculated based on the flue gas volume and flue gas temperature of each section to balance the waste heat of the flue gas with the heat of the steam and hot water. The power generation index of this system can reach 24 kWh / t, and the ore outlet temperature of the annular cooler is ≤120℃.

[0022] The formula for calculating the total amount of ore processed by the annular cooler is: M = F × 1× 2 (Formula 1); In the formula: M is the total amount of ore, in t / h; F is the area of ​​the sintering machine in m². 2 ; 1 represents the utilization factor of the sintering machine. 2 represents the total return coefficient of sintering.

[0023] Based on the feed temperature T of the annular cooler, and considering the different ore and fuel compositions of the sintering waste heat, new projects should refer to the operating data of existing projects, while renovation projects should combine the operating data before the renovation to determine the feed temperature of the annular cooler. With the quantity and temperature of the ore as the heat source for sintering waste heat, the heat capacity of the heat source can be calculated. A waste heat extraction scheme should then be designed based on the ore production and temperature conditions of the heat source.

[0024] The formula for calculating cooling air volume is: Q = C × m × Δt (Formula 2); Where C1×m1×Δt1=C2×m2×Δt2 (Formula 3); In the formula: C1 is the specific heat of the ore; m1 is the mass of the ore; Δt1 is the temperature difference of the ore; C2 is the specific heat of the flue gas; M2 is the flow rate of the flue gas; Δt2 is the temperature difference of the flue gas.

[0025] Based on the amount and temperature of the ore in the annular cooler, the flue gas volume and temperature of each section of the annular cooler are determined to achieve heat balance. As the intermediate carrier for waste heat utilization, the flue gas volume and temperature are crucial for ensuring ore cooling and waste heat output. Flue gas volume and temperature are relevant parameters; selecting a temperature close to the actual conditions and designing a reasonable air volume are essential to guarantee normal heat exchange.

[0026] The formula for calculating the heat balance between steam and hot water is: Q = C × m × Δt (Formula 4); Where C2×m2×Δt2=C3×m3×Δt3 (Formula 5); In the formula: C2 is the specific heat of flue gas; M2 is the mass of flue gas; Δt2 is the temperature difference between flue gas and hot water; C3 is the specific heat of hot water; M3 is the flow rate of hot water; Δt3 is the temperature difference of hot water.

[0027] Based on the heat balance between flue gas waste heat and steam and hot water, the appropriate values ​​of steam parameters are crucial to the efficiency of sintering waste heat power generation. Simultaneously, if hot water is used at the tail end of the waste heat boiler in the low-temperature section of the annular cooler, the exhaust gas temperature at the boiler tail end can be reduced, which is highly beneficial for waste heat extraction and ore cooling in the annular cooler. Based on the flue gas volume and temperature of each section, heat is transferred to hot water and steam through the waste heat boiler to achieve heat balance, and the output of steam and hot water is calculated.

[0028] In this embodiment, zero emissions at the end of the annular cooler (fifth section) are the final guarantee for ore cooling, with cold air entering for further cooling. This embodiment is applicable when the sintering machine utilization coefficient is low, i.e., low output, and the ore temperature entering the annular cooler is not high. Therefore, the calculated hot air temperature in the fifth section is low. Consequently, the hot air from the fifth section is directed to the lower air inlet of the fourth section as cooling air for that section. The final flue gas volume and temperature at the four-section outlet are calculated by balancing the ore heat, flue gas heat, hot water heat, and flue gas volume. The heat from the flue gas in the fourth section is absorbed by the designed heat exchanger 17 to absorb low-temperature waste heat. The temperature of the discharged flue gas is controlled as needed and directly sent to the sintering hot air ignition and flue gas circulation, thus fully recovering the waste heat from the annular cooler. As a final guarantee, the flue gas can be sent to the sintering machine tail dust collector, ensuring that the annular cooler does not emit any external emissions while the ore is cooled.

[0029] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A sintering annular cooler high-temperature zone cross-circulation waste heat recovery and zero-emission system, comprising an annular cooler, an annular cooler blower, a waste heat boiler, a circulating fan, a steam turbine generator set, a condenser, and a condensate pump, wherein the annular cooler is divided into five sections, each section having an annular cooler blower, the annular cooler being equipped with a fume hood, the top of the fume hood being connected to the waste heat boiler via a duct, the steam outlet of the waste heat boiler being connected to the steam turbine generator set, and the condensate from the steam turbine generator set being collected in the condenser and returned to the waste heat boiler via the condensate pump, characterized in that... The waste heat boiler is a two-stage waste heat boiler. The flue gas is taken from the first and second stages. The exhaust air from the bottom of the first and second stage waste heat boiler is returned to the second and third stages via a circulating fan. The flue gas pipe of the third stage is connected to the inlet of the No. 1 annular cooling blower of the first stage. The flue gas pipe of the fifth stage is connected to the inlet of the No. 4 annular cooling blower of the fourth stage. The flue gas of the fourth stage is sent to the sintering production process after heat exchange in a heat exchanger. The steam turbine generator set is a condensing steam turbine generator set with supplementary steam. The high-parameter superheater of the waste heat boiler is connected to the main steam inlet of the condensing steam turbine generator set with supplementary steam. The low-parameter superheater of the waste heat boiler is connected to the supplementary steam port of the condensing steam turbine generator set with supplementary steam.

2. The sintering ring cooler high-temperature zone cross-circulation waste heat recovery and zero-emission system according to claim 1, characterized in that, The fume hood is a partition hood, and the five sections are separated into five relatively isolated spaces. Each section is equipped with a partition valve at the bottom connecting pipe to prevent air leakage between the sections.

3. The sintering ring cooler high-temperature zone cross-circulation waste heat recovery and zero-emission system according to claim 1, characterized in that, The waste heat boiler is a dual-pressure waste heat boiler.

4. The sintering ring cooler high-temperature zone cross-circulation waste heat recovery and zero-emission system according to claim 2, characterized in that, The partition cover structure includes a top cover, partition plates, and a movable plate. The lower surface of the top cover is sealed to the upper ends of the two partition plates respectively. The lower ends of the partition plates are connected to the upper ends of the movable plate by hinges. The lower end of the movable plate overlaps the surface of the ore on the annular cooler. The top cover, partition plates, movable plate, and ore form a relatively sealed space.

5. The sintering ring cooler high-temperature zone cross-circulation waste heat recovery and zero-emission system according to claim 1, characterized in that, The system is equipped with a sintering machine with a utilization coefficient of <1.35, a high feed temperature of <700℃ for the annular cooler, a flue gas temperature of <380℃ for the first stage of the annular cooler, and a flue gas temperature of <250℃ for the third stage of the annular cooler.

6. The sintering ring cooler high-temperature zone cross-circulation waste heat recovery and zero-emission system according to claim 1, characterized in that, The steam parameters for the waste heat boiler are as follows: high parameter steam pressure 1.7±0.2MPa, steam temperature 360±20℃; low parameter steam pressure 0.45±0.2MPa, steam temperature 200±20℃.

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