Waste heat recovery system of denitration heat source and sintering flue gas denitration system

Abstract

The utility model relates to the technical field of sintering flue gas treatment, in particular to a waste heat recovery system of a denitration heat source and a sintering flue gas denitration system.The waste heat recovery system of the denitration heat source comprises a low-temperature GGH heat exchanger, a heat exchange circulating pipeline is connected to the low-temperature GGH heat exchanger, and an organic working medium power generation system is arranged on the heat exchange circulating pipeline; a heat exchange medium is stored in the heat exchange circulating pipeline; the sintering flue gas denitration system comprises a main exhaust fan connected with a sintering flue gas pipeline, the main exhaust fan penetrates through a high-temperature GGH heat exchanger through a pipeline to be connected with a hot blast stove, and the hot blast stove is connected with an SCR reactor. The SCR reactor penetrates through the high-temperature GGH heat exchanger through a pipeline to be connected with the flue gas channel, the flue gas channel is connected with the desulfurizing absorption tower through a tail-section pipeline, and a booster fan is arranged on the tail-section pipeline. The heat of the heat exchange medium in the low-temperature GGH heat exchanger can be used for power generation, the heat recycling efficiency is improved, and meanwhile the sintering flue gas treatment cost is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of sintering flue gas treatment, in particular to a waste heat recovery system of a denitration heat source and a sintering flue gas denitration system. Background Art

[0002] The sintering flue gas generated by the metallurgical industry needs to be denitrated, desulfurized and deeply purified before it can be discharged. SCR denitrification technology (selective catalytic reduction technology) is a common technology for denitrification of sintering flue gas. Its reaction principle is to spray ammonia or enzyme, a reducing agent, into the sintering flue gas under the condition of a catalyst, and the high-temperature reaction will reduce the NO in the sintering flue gas. x Restore to N 2 and H 2 O.

[0003] The working temperature of the commonly used SCR denitrification catalyst is not lower than 300°C. Therefore, in the denitrification process, the sintering flue gas needs to be heated to 300°C before being introduced into the SCR reactor; and the flue gas temperature required for the subsequent desulfurization process is generally between 100-150°C, preferably around 120°C. High temperatures exceeding 150°C will reduce the desulfurization efficiency. Therefore, after the SCR reaction is completed, the sintering flue gas needs to be cooled before desulfurization can be carried out.

[0004] In order to reduce the waste of heat during the heating and cooling process of sintering flue gas, the existing technology mostly uses a high-temperature GGH heat exchanger to exchange heat on the flue gas, that is, the sintering flue gas first passes through the high-temperature GGH heat exchanger, and then passes through a hot blast furnace to be heated to 300°C, and then enters the SCR reactor for denitrification. The high-temperature flue gas after denitrification enters the high-temperature GGH heat exchanger and exchanges heat with the sintering flue gas before heating, so that the flue gas before denitrification is heated and the flue gas after denitrification is cooled, thereby reducing heat loss; however, the temperature of the denitrified flue gas after cooling by the high-temperature GGH heat exchanger is about 160°C, which still does not meet the conditions for desulfurization, and therefore needs to enter the low-temperature GGH heat exchanger for heat exchange again.

[0005] The low-temperature GGH heat exchanger mainly exchanges heat with the flue gas through the heat exchange medium (such as soft water) therein. After the heat exchange, the flue gas is cooled to about 120°C, while the heat exchange medium is heated to 120-140°C. For the heated heat exchange medium, the existing technology mainly cools it down through the plate heat exchanger and the condensing device in sequence and then recycles it. However, the plate heat exchanger has a low efficiency in recycling this part of the heat, which will cause a large heat loss and lead to high sintering flue gas treatment costs. Utility Model Content

[0006] In view of the technical problems that the existing technology of using plate heat exchangers to recover heat from low-temperature GGH heat exchangers has low recovery and reuse efficiency, causes large heat losses, and leads to high sintering flue gas treatment costs, the utility model provides a waste heat recovery system for denitrification heat sources and a sintering flue gas denitrification system, which can utilize the heat of the heat exchange medium in the low-temperature GGH heat exchanger to generate electricity, thereby improving the heat recovery and reuse efficiency while reducing the sintering flue gas treatment cost.

[0007] In the first aspect, the utility model provides a waste heat recovery system for a denitrification heat source, comprising a low-temperature GGH heat exchanger, the low-temperature GGH heat exchanger being provided with a heat exchange outlet, a heat exchange inlet and a flue gas channel, the heat exchange outlet being connected to the heat exchange inlet through a heat exchange circulation pipe, the heat exchange circulation pipe being provided with an organic working fluid power generation system, and the heat exchange circulation pipe storing a heat exchange medium.

[0008] Furthermore, the heat exchange medium is soft water.

[0009] Furthermore, the organic working fluid power generation system includes an organic working fluid evaporator arranged on the heat exchange circulation pipeline, and also includes an organic working fluid circulation pipeline, which passes through the organic working fluid evaporator, the turbine, and the condenser in sequence and is connected end to end to form a closed circuit. The organic working fluid circulation pipeline contains organic working fluid, and the flow direction of the organic working fluid is from the organic working fluid evaporator to the turbine, then to the condenser, and finally back to the organic working fluid evaporator; an impeller is arranged on the turbine, and the impeller is connected to the generator.

[0010] Furthermore, the condenser is connected to the condensation container through a liquid inlet pipe and a liquid outlet pipe respectively, and the condensed liquid in the condenser can be circulated through the condensation container.

[0011] Furthermore, the organic working fluid power generation system also includes an organic working fluid pump arranged on the organic working fluid circulation pipeline. The organic working fluid pump is arranged downstream of the condenser. The organic working fluid first flows through the condenser and then flows through the organic working fluid pump. The organic working fluid pump can provide power for the circulation of the organic working fluid and control the circulation flow rate of the organic working fluid.

[0012] Furthermore, the organic working fluid power generation system also includes a preheater arranged on the heat exchange circulation pipeline, the organic working fluid circulation pipeline passes through the preheater, and the organic working fluid in the organic working fluid circulation pipeline first flows through the preheater and then flows through the organic working fluid evaporator.

[0013] Furthermore, the organic working fluid is R245fa (pentafluoropropane), which has large latent heat of evaporation and specific heat capacity and strong stability, and can be used as a good refrigerant.

[0014] In the second aspect, the utility model provides a sintering flue gas denitrification system including the above-mentioned waste heat recovery system, including a main exhaust fan connected to the sintering flue gas pipeline, the main exhaust fan is connected to the heating pipeline, the heating pipeline passes through the high-temperature GGH heat exchanger and is connected to the hot blast furnace, the hot blast furnace is connected to the SCR reactor through the denitrification flue, and an ammonia atomizing spray device and a dust collector are sequentially arranged in the denitrification flue; the SCR reactor is connected to the cooling pipeline, the cooling pipeline passes through the high-temperature GGH heat exchanger and is connected to the flue gas channel on the low-temperature GGH heat exchanger, the flue gas channel is connected to the desulfurization absorption tower through the terminal pipeline, and a booster fan is arranged on the terminal pipeline.

[0015] Furthermore, the dust collector is a mesh chain dust collector.

[0016] The beneficial effects of the utility model are:

[0017] The utility model is arranged on the low-temperature GGH heat exchanger to connect the heat exchange circulation pipeline, and the organic working fluid power generation system is arranged on the heat exchange circulation pipeline. The heat of the heated heat exchange medium can be used to evaporate the organic working fluid and then drive the generator to generate electricity. The thermal energy of the sintering flue gas can be converted into electrical energy for waste heat recovery, and the efficiency of heat recovery and reuse is high; the collected electrical energy can generate considerable economic benefits, which can improve the economic value of waste heat recovery and thus reduce the treatment cost of the sintering flue gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the utility model or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is a schematic diagram of the structure of the waste heat recovery system in Example 1.

[0020] Figure 2 This is a schematic diagram of the structure of the sintering flue gas denitrification system in Example 2.

[0021] In the figure, 1-low-temperature GGH heat exchanger, 2-organic working fluid evaporator, 3-turbine, 4-generator, 5-condenser, 6-condensation container, 7-organic working fluid pump, 8-preheater, 9-main exhaust fan, 10-high-temperature GGH heat exchanger, 11-hot blast furnace, 12-SCR reactor, 13-boosting fan, 14-desulfurization absorption tower. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0023] Example 1

[0024] A waste heat recovery system for a denitrification heat source comprises a low-temperature GGH heat exchanger 1, wherein the low-temperature GGH heat exchanger 1 is provided with a heat exchange outlet, a heat exchange inlet and a flue gas channel, wherein the heat exchange outlet is connected to the heat exchange inlet through a heat exchange circulation pipeline, wherein an organic working fluid power generation system is provided on the heat exchange circulation pipeline, wherein a heat exchange medium is stored in the heat exchange circulation pipeline, and the heat exchange medium is soft water; the organic working fluid power generation system comprises an organic working fluid evaporator 2 arranged on the heat exchange circulation pipeline, and further comprises an organic working fluid circulation pipeline, wherein the organic working fluid circulation pipeline sequentially passes through the organic working fluid evaporator 2, the vortex The turbine 3, the condenser 5, the organic working fluid pump 7, and the preheater 8 are connected end to end to form a closed circuit, and the preheater 8 is arranged on the heat exchange circulation pipeline; the organic working fluid circulation pipeline contains an organic working fluid, and the organic working fluid is R245fa. The flow direction of the organic working fluid is from the organic working fluid evaporator 2 to the turbine 3, and then flows through the condenser 5, the organic working fluid pump 7, the preheater 8 in sequence, and finally returns to the organic working fluid evaporator 2; the condenser 5 is connected to the condensation container 6 through the liquid inlet pipe and the liquid outlet pipe respectively; the turbine 3 is provided with an impeller, and the impeller is connected to the generator 4.

[0025] The working principle of Example 1 is as follows: the flue gas after denitrification enters the low-temperature GGH heat exchanger 1, and the heat exchange medium in the low-temperature GGH heat exchanger 1 is heated to 120-130°C. The heat exchange medium enters the heat exchange circulation pipeline through the heat exchange outlet, and successively exchanges heat with the organic working fluid in the preheater 8 and the organic working fluid evaporator 2. The heat exchange medium is cooled down and enters the heat exchange inlet through the heat exchange circulation pipeline, and returns to the low-temperature GGH heat exchanger 1 to continue circulating; the organic working fluid in the organic working fluid evaporator 2 evaporates into a gaseous state after heat exchange, and the gaseous organic working fluid enters the turbine 3 to drive the impeller to rotate, and the impeller drives the generator to generate electricity; the gaseous organic working fluid continues to enter the condenser 5, condenses into a liquid state under the action of the condenser 5, enters the organic working fluid pump 7, and returns to the preheater 8 under the action of the organic working fluid pump 7 to continue circulating.

[0026] Example 2

[0027] A sintering flue gas denitrification system using the waste heat recovery system of Example 1 includes a main exhaust fan 9 connected to a sintering flue gas pipeline, the main exhaust fan 9 is connected to a heating pipeline, the heating pipeline passes through a high-temperature GGH heat exchanger 10 and is connected to a hot blast furnace 11, the hot blast furnace 11 is connected to an SCR reactor 12 through a denitrification flue, and an ammonia atomizing spray device and a mesh chain dust collector are sequentially arranged in the denitrification flue; the SCR reactor 12 is connected to a cooling pipeline, the cooling pipeline passes through the high-temperature GGH heat exchanger 10 and is connected to a flue gas channel on a low-temperature GGH heat exchanger 1, the flue gas channel is connected to a desulfurization absorption tower 14 through a terminal pipeline, and a booster fan 13 is arranged on the terminal pipeline.

[0028] The working principle of embodiment 2 is:

[0029] The sintering flue gas (temperature is about 130°C) entering the sintering flue gas pipeline enters the heating pipeline under the action of the main exhaust fan 9, is heated to 300°C under the joint action of the high-temperature GGH heat exchanger 10 and the hot blast furnace 11, and then enters the denitrification flue. The ammonia water atomizing spraying device arranged in the denitrification flue sprays atomized ammonia water to the flue gas at 300°C. After mixing, the flue gas is dedusted by the mesh chain dust collector and enters the SCR reactor 12 for denitrification. The flue gas after denitrification enters the cooling pipeline and is cooled to about 160 degrees Celsius under the action of the high-temperature GGH heat exchanger 10, and then enters the low-temperature GGH heat exchanger 1 to perform the same heat exchange as in Example 1, and the flue gas after denitrification is further cooled to 120°C, and then enters the desulfurization absorption tower 14 under the action of the booster fan 13 for desulfurization and deep purification.

[0030] Although the present invention is described in detail by referring to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person skilled in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person skilled in the art who is familiar with the present technical field may easily think of changes or substitutions within the technical scope disclosed in the present invention, and these shall be within the scope of protection of the present invention.

Claims

1. A waste heat recovery system for a denitrification heat source, comprising a low-temperature GGH heat exchanger, characterized in that: The low-temperature GGH heat exchanger is provided with a heat exchange outlet, a heat exchange inlet and a flue gas channel. The heat exchange outlet is connected to the heat exchange inlet through a heat exchange circulation pipeline. An organic working fluid power generation system is provided on the heat exchange circulation pipeline. The heat exchange circulation pipeline stores a heat exchange medium. The organic working fluid power generation system includes an organic working fluid evaporator arranged on a heat exchange circulation pipeline, and also includes an organic working fluid circulation pipeline. The organic working fluid circulation pipeline passes through the organic working fluid evaporator, a turbine, and a condenser in sequence and is connected end to end to form a closed circuit. The organic working fluid circulation pipeline contains an organic working fluid, and the organic working fluid flows from the organic working fluid evaporator to the turbine, then to the condenser, and finally returns to the organic working fluid evaporator; an impeller is arranged on the turbine, and the impeller is connected to the generator.

2. The waste heat recovery system according to claim 1, characterized in that: The heat exchange medium is soft water.

3. The waste heat recovery system according to claim 1, characterized in that: The condenser is connected to the condensation container through a liquid inlet pipe and a liquid outlet pipe respectively.

4. The waste heat recovery system according to claim 1, characterized in that: The organic working fluid power generation system also includes an organic working fluid pump arranged on the organic working fluid circulation pipeline. The organic working fluid pump is arranged downstream of the condenser. The organic working fluid first flows through the condenser and then flows through the organic working fluid pump.

5. The waste heat recovery system according to claim 1, characterized in that: The organic working fluid power generation system also includes a preheater arranged on the heat exchange circulation pipeline. The organic working fluid circulation pipeline passes through the preheater. The organic working fluid in the organic working fluid circulation pipeline first flows through the preheater and then flows through the organic working fluid evaporator.

6. The waste heat recovery system according to claim 1, characterized in that: The organic working fluid is R245fa.

7. A sintering flue gas denitration system comprising the waste heat recovery system according to claim 1, characterized in that: It includes a main exhaust fan connected to the sintering flue gas duct, the main exhaust fan is connected to the heating duct, the heating duct passes through the high-temperature GGH heat exchanger and is connected to the hot blast furnace, the hot blast furnace is connected to the SCR reactor through the denitrification flue, and an ammonia atomizing spray device and a dust collector are arranged in the denitrification flue in sequence; the SCR reactor is connected to the cooling duct, the cooling duct passes through the high-temperature GGH heat exchanger and is connected to the flue gas channel on the low-temperature GGH heat exchanger, the flue gas channel is connected to the desulfurization absorption tower through the terminal pipe, and a booster fan is arranged on the terminal pipe.

8. The sintering flue gas denitration system according to claim 7, characterized in that: The dust collector is a mesh chain dust collector.

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