Environment-friendly and efficient sintering circular cooler low-temperature waste heat recovery system

Abstract

The utility model discloses an environment-friendly and efficient sintering circular cooler low-temperature waste heat recovery system, and belongs to the technical field of waste heat recovery and utilization in the steel smelting industry. The problems that in the prior art, low-temperature waste gas of the sinter cooler is directly emptied, or simple and low-efficiency waste heat recovery is conducted, so that a large amount of heat which is not fully utilized is lost, and the energy-saving requirement is not met are solved. According to the technical key points, flue gas of the third section of the circular cooler is conveyed to the top of the low-temperature combined waste heat boiler through a pipeline and exchanges heat with a steam-water heat exchange part; a lower circulating waste gas outlet of the low-temperature combined waste heat boiler is connected with an inlet of a cooling air blower of the fifth section of the annular cooler through a pipeline, a flue gas outlet of the fifth section of the annular cooler is connected with an inlet of a cooling air blower of the fourth section of the annular cooler through a pipeline, and a flue gas outlet of the fourth section of the annular cooler is connected with an inlet of a cooling air blower of the third section of the annular cooler through a pipeline. The grate type cooling device is used for sinter cooling in the iron and steel smelting industry or other occasions needing grate type cooling of materials, and has the effects of reducing waste gas emission and improving the low-temperature waste heat recovery efficiency.

Description

Technical Field

[0001] The utility model relates to a low-temperature waste heat recovery system for a sintering ring cooler, in particular to an environmentally friendly and efficient low-temperature waste heat recovery system for a sintering ring cooler, and belongs to the technical field of waste heat recovery and utilization in the steel smelting industry. Background Art

[0002] According to the currently known information, the existing sintering cooler and waste heat utilization system (see Figure 2 ), generally, the high-temperature exhaust gas from the first two stages is recovered, and after the waste heat boiler absorbs the heat, the exhaust gas is sent to the lower part of the first two stages of the cooler for blasting using hot air circulation.

[0003] There are cases where the low-temperature exhaust gas from the third stage of the ring cooler is recycled to the sintering machine for hot air insulation, but in most steel companies, the exhaust gas after the third stage is directly discharged into the air.

[0004] Currently, a small number of steel companies use the low-temperature flue gas from the 3rd to 4th stage of the ring cooler to generate hot water for winter heating and ORC low-temperature organic working fluid power generation.

[0005] At present, the waste heat of the low-temperature flue gas at the rear of the sintering ring cooler is utilized by directly setting a flue gas-hot water heat exchanger at the flue gas outlet to simply recover the waste heat of the low-temperature flue gas. The recovery efficiency is low, and the economic value of the generated hot water is low.

[0006] In the existing technology, the utilization efficiency of low-temperature flue gas after the third stage of the sintering cooler is extremely low, and it is even directly discharged. The current model has the following defects: 1. The waste gas from the 3rd to 5th stage of the rear part of the sintering cooler is generally not recycled, and a large amount of waste gas is directly discharged, causing a certain degree of pollution to the environment. 2. A large amount of low-temperature waste gas of 130 to 250℃ in the middle and rear stages of the sintering cooler is discharged, or simply waste heat is recovered, resulting in a large amount of underutilized heat loss, which does not meet the increasingly high energy-saving requirements. Utility Model Content

[0007] In view of the above facts, the purpose of the utility model is to address the technical problem that in the prior art, the low-temperature exhaust gas of the sintering cooler is either discharged or the waste heat is simply recovered, resulting in a large amount of underutilized heat loss, which does not meet the increasingly high energy-saving requirements. Thus, an environmentally friendly and efficient low-temperature waste heat recovery system for the sintering ring cooler is designed. The utility model is used for sintering ore cooling in the iron and steel smelting industry or other occasions where grate cooling of materials is required, which can reduce exhaust gas emissions and greatly improve the efficiency of low-temperature waste heat recovery. The utility model is used in the sintering ore cooling process of steel production, which can greatly reduce the exhaust gas emitted by the cooler or achieve zero emission. It can utilize the low-temperature exhaust gas currently discharged into the air to efficiently recover the low-temperature flue gas waste heat of the sintering ring cooler, and the recovered low-temperature waste heat can be used for power generation or heating.

[0008] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0009] Solution: An environmentally friendly and efficient low-temperature waste heat recovery system for a sintering ring cooler, comprising a low-temperature combined waste heat boiler, wherein a steam-water heat exchange section and an organic working fluid heat exchange section are arranged from top to bottom in the low-temperature combined waste heat boiler, and the organic working fluid heat exchange section is cyclically connected to the ORC power generation system; the flue gas from section 3 of the ring cooler is transmitted to the top of the low-temperature combined waste heat boiler through a pipeline to exchange heat with the steam-water heat exchange section, the lower circulating exhaust gas outlet of the low-temperature combined waste heat boiler is connected to the inlet of the cooling blower of section 5 of the ring cooler through a pipeline, the flue gas outlet of section 5 of the ring cooler is connected to the inlet of the cooling blower of section 4 of the ring cooler through a pipeline, and the flue gas outlet of section 4 of the ring cooler is connected to the inlet of the cooling blower of section 3 of the ring cooler through a pipeline.

[0010] Furthermore: a circulating cooling water heat exchanger is additionally provided at the circulating exhaust gas outlet at the lower part of the low-temperature combined waste heat boiler.

[0011] Furthermore: the flue gas temperature of the 3rd section of the ring cooler is 220-260°C, the flue gas temperature of the 4th section of the ring cooler is 130-160°C, the flue gas temperature of the 5th section of the ring cooler is 70-90°C, and the lower circulating exhaust gas temperature of the low-temperature combined waste heat boiler is 50-60°C.

[0012] Furthermore: the organic working fluid of the ORC power generation system is R245fa.

[0013] The effects achieved by the utility model are:

[0014] The utility model utilizes the existing sintering ring cooling or belt cooling machine body, transforms the cooling blower and waste gas collection system after the third stage of the ring cooling machine, collects the waste gas discharged from each stage of the next stage cooler, and sends it to the inlet of the previous stage cooling blower through a pipeline. The low-temperature waste gas of the next stage is heated by the ore material with a higher temperature of the previous stage, and the temperature is gradually increased, and finally the waste gas with a higher temperature is obtained. Compared with the parallel recovery of multiple stages of waste gas, the utility model greatly reduces the waste gas flow, and provides good conditions for subsequent improvement of waste heat recovery efficiency and reduction of waste heat exchanger investment. The utility model is used for sintering ore cooling in the steel smelting industry or other occasions where grate cooling of materials is required, which can reduce waste gas emissions and greatly improve the recovery efficiency of low-temperature waste heat. The utility model is used in the sintering ore cooling process of steel production, which can greatly reduce the waste gas discharged by the cooler or achieve zero emissions, and can use the low-temperature waste gas currently discharged to the air to efficiently recover the waste heat of the low-temperature flue gas of the sintering ring cooler, and recover the low-temperature waste heat for power generation or heating. The utility model makes full use of the original sintered ore cooler and waste heat equipment, saves investment, and effectively shortens the investment recovery period of the low-temperature waste heat project. Specifically:

[0015] 1. The sintering ring cooler waste gas is heated in series step by step, which not only achieves zero emission of the ring cooler, avoids a large amount of waste gas emission into the air from the ring cooler, and significantly improves environmental pollution near the cooler; it can also efficiently recover and utilize waste gas heat to generate electricity, contributing to energy conservation in steel plants.

[0016] 2. The low-temperature exhaust gas from the annular cooler is heated step by step to finally obtain exhaust gas with a higher temperature, which can reduce the exhaust gas flow entering the low-temperature combined waste heat boiler by more than 50%, and can also greatly improve the heat exchange efficiency of the low-temperature combined waste heat boiler and reduce the investment in the low-temperature combined waste heat boiler.

[0017] 3. The waste gas with higher temperature is obtained by heating in stages, which greatly increases the available waste gas enthalpy value and reduces the heat carried away by the exhaust gas of the waste heat boiler. In addition, the waste heat boiler can produce waste heat steam with higher parameters, which greatly improves the waste heat recovery efficiency and the power generation efficiency of the generator set. The use of the utility model technology can increase the sintering waste heat power generation by about 8kWh per ton of ore.

[0018] 4. The utility model can make full use of the original sinter cooler and auxiliary equipment, only transform the blower and exhaust system, and add a low-temperature combined waste heat boiler and ORC generator set, which can greatly reduce the project investment.

[0019] 5. The utility model can also add a circulating cooling water heat exchanger at the discharge point of the low-temperature combined waste heat boiler, which can reduce the circulating exhaust gas temperature to below 50°C and then return it to the inlet of the cooling blower, thereby ensuring the cooling effect of the cooler and ensuring that the discharge temperature of the cooler is qualified. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of an environmentally friendly and efficient sintering ring cooler low-temperature waste heat recovery system of the utility model;

[0021] Figure 2 It is a structural schematic diagram of the existing sintering cooler and waste heat utilization system.

[0022] Among them: 1- low-temperature combined waste heat boiler; 2- cooling blower of the 5th section of the ring cooler; 3- cooling blower of the 4th section of the ring cooler; 4- cooling blower of the 3rd section of the ring cooler; 10- steam-water heat exchange part; 11- organic working fluid heat exchange part. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0024] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so as to describe the embodiments of the present application described herein.

[0025] In the present application, the directions or positional relationships indicated by the terms "upper", "lower", "inner", "middle", "outer", "front", "back", etc. are based on the directions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific direction, or to be constructed and operated in a specific direction.

[0026] In addition, the terms "disposed", "connected", and "fixed" should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0027] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. Figure 1 The present application is described in detail with reference to embodiments.

[0028] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0029] Embodiment 1: This embodiment is an environmentally friendly and efficient low-temperature waste heat recovery system for sintering ring coolers, comprising a low-temperature combined waste heat boiler 1, in which a steam-water heat exchange part 10 and an organic working fluid heat exchange part 11 are arranged from top to bottom, and the organic working fluid heat exchange part 11 is cyclically connected to the ORC power generation system; the flue gas of the 3rd section of the ring cooler is transmitted to the top of the low-temperature combined waste heat boiler 1 through a pipeline, and heat is exchanged with the steam-water heat exchange part 10, the lower circulating exhaust gas outlet of the low-temperature combined waste heat boiler 1 is connected to the inlet of the cooling blower 2 of the 5th section of the ring cooler through a pipeline, the flue gas outlet of the 5th section of the ring cooler is connected to the inlet of the cooling blower 3 of the 4th section of the ring cooler through a pipeline, and the flue gas outlet of the 4th section of the ring cooler is connected to the inlet of the cooling blower 4 of the 3rd section of the ring cooler through a pipeline. A circulating cooling water heat exchanger is added at the lower circulating exhaust gas outlet of the low-temperature combined waste heat boiler 1. The flue gas temperature of the ring cooler 3 is 260°C, the flue gas temperature of the ring cooler 4 is 160°C, the flue gas temperature of the ring cooler 5 is 90°C, and the lower circulating waste gas temperature of the low-temperature combined waste heat boiler 1 is 50°C. The organic working fluid of the ORC power generation system is R245fa.

[0030] In this example, a 360m 2 Taking the sintering ring cooler as an example, the following sintering ring cooler heat balance simulation calculation and waste heat recovery system thermal simulation calculation are provided as follows:

[0031]

[0032]

[0033] The above simulation calculations show that:

[0034] 1. The discharge temperature of the ring cooler is 85℃, which is lower than the 120℃ required by the specification.

[0035] 2. The full circulation of exhaust gas is realized, reaching the environmental protection standard of zero emission.

[0036] 3. The efficient waste heat recovery of the low-temperature exhaust gas at the tail of the cooler is realized. Combined with the power generation power of the ORC unit, the waste heat power generation power can reach 4.1MW, and the power generation per ton of ore reaches 8.23kWh.

[0037] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

[0038] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An environmentally friendly and efficient low-temperature waste heat recovery system for a sintering ring cooler, comprising a low-temperature combined waste heat boiler (1), wherein a steam-water heat exchange portion (10) and an organic working fluid heat exchange portion (11) are arranged from top to bottom in the low-temperature combined waste heat boiler (1), and the organic working fluid heat exchange portion (11) is cyclically connected to an ORC power generation system; and characterized in that: The flue gas of the 3rd section of the ring cooler is transmitted to the top of the low-temperature combined waste heat boiler (1) through a pipeline, and exchanges heat with the steam-water heat exchange part (10); the lower circulating exhaust gas outlet of the low-temperature combined waste heat boiler (1) is connected to the inlet of the cooling blower (2) of the 5th section of the ring cooler through a pipeline, the flue gas outlet of the 5th section of the ring cooler is connected to the inlet of the cooling blower (3) of the 4th section of the ring cooler through a pipeline, and the flue gas outlet of the 4th section of the ring cooler is connected to the inlet of the cooling blower (4) of the 3rd section of the ring cooler through a pipeline.

2. The environmentally friendly and efficient sintering ring cooler low-temperature waste heat recovery system according to claim 1 is characterized by: A circulating cooling water heat exchanger is additionally provided at the circulating exhaust gas outlet at the lower part of the low-temperature combined waste heat boiler (1).

3. The environmentally friendly and efficient sintering ring cooler low-temperature waste heat recovery system according to claim 2 is characterized by: The flue gas temperature of the ring cooler 3 section is 220-260°C, the flue gas temperature of the ring cooler 4 section is 130-160°C, the flue gas temperature of the ring cooler 5 section is 70-90°C, and the lower circulating waste gas temperature of the low-temperature combined waste heat boiler (1) is 50-60°C.

4. An environmentally friendly and efficient sintering ring cooler low-temperature waste heat recovery system according to any one of claims 1 to 3, characterized in that: The organic working fluid of the ORC power generation system is R245fa.

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