Combustion-supporting air and coal gas preheating system of hot blast stove

Abstract

The invention belongs to the technical field of smelting reduction ironmaking, and particularly relates to a hot-blast stove combustion-supporting air and coal gas preheating system which is used for increasing the preheating temperature of hot-blast stove combustion-supporting air and coal gas so as to meet the hot air temperature requirement of a Hismelt ironmaking process. Comprising a smelting reduction furnace, a waste heat boiler, a cyclone dust collector, an air preheater, a dust collector, a combustion fan and a hot blast stove, the smelting reduction furnace is sequentially connected with a waste gas cover, a cyclone dust collector, an air preheater, a dust collector and a hot blast stove; and the combustion fan is sequentially connected with the air preheater and the hot blast stove. The scheme has the following advantages that waste heat of coal gas is fully utilized, high-temperature coal gas directly enters the air preheater to heat combustion-supporting air, and the waste heat utilization efficiency is higher; after passing through the air preheater, combustion-supporting air is heated to 300 DEG C or above, the temperature of coal gas is reduced to about 500 DEG C, the coal gas is used for burning of a hot-blast stove, and the target that the temperature of hot air is 1200 DEG C can be achieved; the system is simple in structure and reliable in operation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of smelting reduction ironmaking, and particularly relates to a hot blast stove combustion air and gas preheating system for increasing the preheating temperature of combustion air and gas of a hot blast stove to meet the hot blast temperature requirement of a Hismelt ironmaking process. BACKGROUND

[0002] The smelting reduction ironmaking is Hismelt ironmaking.

[0003] The Hismelt ironmaking directly uses iron ore powder and coal powder for ironmaking, and thus the coking and sintering processes are omitted. The smelting process is that the ore powder and the granular coal are directly sprayed into a slag-iron bath through an ore powder spray gun and a granular coal spray gun, and the hot blast is sprayed into a space above the bath from the top of the reduction furnace; the oxygen in the hot blast is combusted with the CO and hydrogen generated by the reduction reaction of the bath to provide heat for the bath reaction.

[0004] The gas generated by the smelting reduction furnace has a temperature of 1400℃ or above, and after being cooled by a waste gas hood, the gas has a temperature of 900℃ or below. After being treated by a cyclone dust collector, the gas is treated by a waste heat boiler to produce steam, and the gas is cooled to ≤200℃, and then enters a bag filter for purification. The purified gas enters a clean gas pipeline.

[0005] The system is provided with a hot blast stove for heating cold air from a blower. In order to improve the heating capacity of the hot blast stove, the combustion air and the gas need to be preheated. A plate heat exchanger is used to preheat the combustion air and the gas by using the 350℃ waste gas generated by the combustion of the hot blast stove. Since the temperature of the waste gas as a heat source is low, the preheating temperature can only reach 150-180℃. In addition, the calorific value of the gas generated by the Hismelt ironmaking is low, only 2800-3000kJ / m 3 Left and right, and the hot blast temperature can only reach about 1050℃, but the process requires the hot blast temperature to be 1200℃.

[0006] In the document “Blast Furnace Design: Theory and Practice of Ironmaking Process Design” (page 559) of Metallurgical Industry Press, the preheating temperature of the combustion air is increased by 100℃, and the theoretical combustion temperature is increased by 31℃; the preheating temperature of the gas is increased by 100℃, and the theoretical combustion temperature is increased by 52℃.

[0007] To solve the problems in the prior art, the present application provides a hot blast stove combustion air and gas preheating system, which can greatly increase the preheating temperature of the combustion air and the gas to achieve the purpose of increasing the hot blast temperature. SUMMARY

[0008] Explanation of terms: high-temperature gas refers to the gas that is cooled to 900℃ or below by a waste gas hood and coarsely cleaned by a cyclone dust collector.

[0009] Technical problems solved

[0010] Rationally use the heat of high-temperature coal gas, increase the temperature of coal gas and combustion air of hot blast stove, and realize the hot blast temperature of 1200 DEG C under the condition of low coal gas heat value and no mixing of natural gas.

[0011] To solve the above problems, the technical scheme is provided as follows:

[0012] A hot blast stove combustion air and coal gas preheating system, through unique design, realizes efficient combustion air and coal gas preheating, comprising a smelting reduction furnace, an exhaust cover, a cyclone dust collector, an air preheater, a dust collector, a combustion air fan and a hot blast stove; the smelting reduction furnace is sequentially connected with the exhaust cover, the cyclone dust collector, the air preheater, the dust collector and the hot blast stove; the combustion air fan is sequentially connected with the air preheater and the hot blast stove; the air preheater is used for heating combustion air by high-temperature coal gas from the cyclone dust collector.

[0013] Preferably, the air preheater is a cylindrical structure, comprising an outer shell, a duct and an end plate, the end plate is fixedly installed at both ends of the inner part of the outer shell, and a plurality of ducts are uniformly installed on the end plate; one end of the air preheater is provided with a coal gas inlet, and the side wall is provided with an air outlet; the other end is provided with a coal gas outlet, and the side wall is provided with an air inlet.

[0014] Preferably, the outer shell, the duct and the end plate of the air preheater are made of 310S, which has good high-temperature resistance and can work stably in a high-temperature environment; the outer shell adopts internal and / or external thermal insulation, the internal thermal insulation adopts 100mm-thick lightweight sprayed material, and the external thermal insulation adopts ceramic fiber cotton, thereby improving the heat exchange efficiency of the air preheater and reducing heat loss.

[0015] Preferably, the dust collector is a bag filter, and the filter bag is made of one of a cloth bag, a ceramic filter bag and a stainless steel wire filter bag; the cloth bag has a temperature resistance ≤280 DEG C; the ceramic filter bag has a temperature resistance ≤800 DEG C; the stainless steel wire filter bag has a temperature resistance ≤500 DEG C; and the filter bag material is selected according to the temperature of the coal gas after the air preheater.

[0016] Preferably, the dust collector inlet is connected with the coal gas pressurizing machine outlet, or the dust collector outlet is connected with the coal gas pressurizing machine outlet; and the coal gas pressurizing machine inlet is connected with the clean coal gas pipeline. Part of the clean coal gas is mixed to adjust the temperature of the coal gas entering the hot blast stove to the required temperature.

[0017] Preferably, the hot blast stove is connected with a desulfurization and denitrification device and a chimney.

[0018] Further, the coal gas generated by the smelting reduction furnace has a temperature of 1400 DEG C or more, and after being cooled by the exhaust hood, the temperature of the coal gas is 900 DEG C or less, and the coal gas is divided into two routes after being treated by the cyclone dust collector, one route of the coal gas enters the air preheater, and the other route of the coal gas is cooled to 200 DEG C or less by the waste heat boiler, and then enters the bag-type dust collector for purification, and the purified coal gas enters the clean coal gas pipeline.

[0019] Compared with the prior art, the scheme has the following advantages:

[0020] 1 The waste heat of the coal gas is fully utilized, the high-temperature coal gas directly enters the air preheater to heat the combustion-supporting air, and compared with the high-temperature coal gas entering the waste heat boiler to produce steam, the waste heat utilization efficiency is higher when the high-temperature coal gas is used to heat the combustion-supporting air.

[0021] 2 The combustion-supporting air is heated to 300 DEG C or more after being treated by the air preheater, and the temperature of the coal gas is reduced to about 500 DEG C, and is used for heating the hot blast stove, and the target of 1200 DEG C of the hot blast temperature can be achieved.

[0022] 3 The design has a unique concept, the system structure is simple, and the operation is reliable. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a flow chart of a hot blast stove combustion-supporting air and coal gas preheating system

[0024] Figure 2 is a schematic diagram of a heat exchanger

[0025] LEGEND

[0026] 1 smelting reduction furnace, 2 exhaust hood, 3 cyclone dust collector, 4 air preheater, 41 outer shell, 42 conduit, 43 end plate, 44 coal gas inlet, 45 coal gas outlet, 46 air inlet, 47 air outlet, 5 combustion-supporting fan, 6 dust collector, 7 waste heat boiler, 8 bag-type dust collector, 9 hot blast stove, 10 coal gas pressurizer,

[0027] 11 desulfurization and denitrification device, 12 chimney, 13 clean coal gas pipeline; DETAILED DESCRIPTION

[0028] The embodiments of the present application are described in detail below with reference to the drawings, so that the ordinary skilled in the art can easily implement the present application, and the present application can be embodied in various forms, and is not limited to this description.

[0029] Example 1 is described below with reference to the drawings. Figure 1 , Figure 2

[0030] ​The hot blast stove combustion air and coal gas preheating system comprises a smelting reduction furnace 1, a waste gas cover 2, a cyclone dust collector 3, an air preheater 4, a dust collector 6, a combustion air fan 5 and a hot blast stove 9, wherein the smelting reduction furnace 1 is sequentially connected with the waste gas cover 2, the cyclone dust collector 3, the air preheater 4, the dust collector 6 and the hot blast stove 9; the combustion air fan 5 is sequentially connected with the air preheater 4 and the hot blast stove 9; and the air preheater 4 is used for heating the combustion air with high-temperature coal gas from the cyclone dust collector 3.

[0031] The waste gas cover 2 is a waste heat utilization device connected between the smelting reduction furnace 1 and the cyclone dust collector 3, which comprises a circular tube and a mode wall mounted on the inner wall of the tube, and the mode wall is internally communicated with desalted water; the coal gas with a temperature of 1400 DEG C or above generated by the smelting reduction furnace 1 enters the waste gas cover 2, the heat of the coal gas is transferred to the desalted water to generate steam, and the temperature of the coal gas is reduced to 900 DEG C to 600 DEG C when the coal gas reaches the outlet of the waste gas cover 2.

[0032] The high-temperature coal gas is the coal gas generated by smelting of the smelting reduction furnace 1, which is cooled by the waste gas cover 2 and coarsely dusted by the cyclone dust collector 3 (coal gas temperature: 900 DEG C to 600 DEG C, dust content: ≤10 g / Nm 3 ).

[0033] The air preheater 4 is in a cylindrical structure, which comprises an outer shell 41, a guide pipe 42 and an end plate 43, the end plate 43 is fixedly mounted at both ends of the inner part of the outer shell 41, and a plurality of guide pipes 42 are uniformly mounted on the end plate 43; one end of the air preheater 4 is provided with a coal gas inlet 44, and the side wall is provided with an air outlet 46; the other end is provided with a coal gas outlet 45, and the side wall is provided with an air inlet 47.

[0034] The outer shell 41, the guide pipe 42 and the end plate 43 of the air preheater 4 are made of 310S; the outer shell is internally and externally heat-insulated.

[0035] The dust collector 6 is a bag filter, the filter bag is made of ceramic filter bag, and the working temperature is 650 DEG C.

[0036] Further, the coal gas generated by the smelting reduction furnace 1 has a temperature of ≥1400 DEG C, the temperature of the coal gas is ≤900 DEG C after being cooled by the waste gas cover 2, and the coal gas is divided into two routes after being treated by the cyclone dust collector 3, one route of the coal gas enters the air preheater 4, and the other route of the coal gas is cooled to ≤200 DEG C by the waste heat boiler 7, then enters the bag dust collector 8 for purification, and the purified coal gas enters the clean coal gas pipeline 13.

[0037] The preheated combustion air and coal gas are used for heating the hot blast stove 9, the waste flue gas generated by heating the hot blast stove is treated by the desulfurization and denitrification device 11, then is discharged through the chimney 12, and the heated hot blast stove is used for heating the cold air, and the cold air is sent into the smelting reduction furnace 1 after being heated to ≥1200 DEG C.

[0038] A cut-off valve (not shown) is provided in the gas pipe connected to the air preheater 4 and the hot blast stove 9, for cutting off the gas when the hot blast stove is stopped.

[0039] A flow regulating valve (not shown) is also provided in the gas pipe connected to the air preheater 4 and the hot blast stove 9, for regulating the amount of gas during the process of starting the hot blast stove.

[0040] A cut-off valve (not shown) is provided in the combustion air pipe connected to the air preheater 4 and the hot blast stove 9, for cutting off the combustion air when the hot blast stove is stopped.

[0041] A flow regulating valve (not shown) is also provided in the combustion air pipe connected to the air preheater 4 and the hot blast stove 9, for regulating the amount of combustion air during the process of starting the hot blast stove.

[0042] The working system of the hot blast stove 9: The hot blast stove 9 comprises a combustion chamber and a regenerative type, the combustion chamber is provided with a gas and combustion air burner, and the regenerative type is filled with refractory checker bricks as the regenerator; when the hot blast stove is working, the high-temperature flue gas generated by the combustion in the combustion chamber is used to heat the regenerator, then the stove is stopped, and cold air is introduced into the hot blast stove, and the cold air exchanges heat with the regenerator, and the cold air is heated into hot air.

[0043] Three hot blast stoves 9 are provided, two of which are used for burning, and one is used for heating cold air.

[0044] Part of the process parameters:

[0045] The amount of air required for smelting in the smelting reduction furnace 1: 140,000 m 3 / h, which needs to be heated by the hot blast stove

[0046] The amount of combustion air required for the hot blast stove: 60,000 m 3 / h, 50°C before entering the air preheater, and 400°C after leaving the air preheater

[0047] The amount of gas required for the hot blast stove: 80,000 m 3 / h, 750°C before entering the air preheater, and 540°C after leaving the air preheater

[0048] The heat exchange area of the air preheater 4: 500 m 2

[0049] The calorific value of the gas used for the hot blast stove: 2,800 kJ / m 3

[0050] The temperature of the hot air heated by the hot blast stove: 1,250°C.

[0051] Example 2

[0052] The other parts are the same as in Example 1,

[0053] The inlet pipe of the dust collector 6 is connected with the outlet of the gas pressurizer 10, and the inlet of the gas pressurizer 10 is connected with the clean gas pipe 13. By mixing a part of the clean gas into the outlet pipe of the dust collector 6, the temperature of the gas entering the hot blast stove 9 is adjusted to reach the required temperature in the process. The filter bag of the dust collector 6 is made of cloth bag.

[0054] Part of the process parameters:

[0055] The hot blast volume of the hot blast stove: 140000 m 3 / h

[0056] The combustion air volume: 60000 m 3 / h, 50℃ before entering the air preheater, 300℃ after leaving the air preheater

[0057] The gas volume: 60000 m 3 / h, 750℃ before entering the air preheater, 350℃ after leaving the air preheater, 20000 m 3 / h of clean gas after mixing, the temperature is 260℃

[0058] The heat exchange area of the air preheater: 500 m 2

[0059] The gas calorific value: 3000 kJ / m 3

[0060] The hot blast temperature: 1200℃.

[0061] The hot blast volume required by the smelting of the smelting reduction furnace 1: 140000 m 3 / h, which needs to be heated by the hot blast stove

[0062] The combustion air volume required for the hot blast stove burning: 60000 m 3 / h, 50℃ before entering the air preheater, 400℃ after leaving the air preheater

[0063] The gas volume required for the hot blast stove burning: 80000 m 3 / h; of which, 60000 m 3 / h enters the air preheater, 750℃ before entering the air preheater, 350℃ after leaving the air preheater, then 20000 m 3 / h of clean gas is mixed at the inlet of the dust collector 6, the temperature of the mixed gas is 260℃, and the gas after being cleaned by the dust collector is used for the hot blast stove burning.

[0064] The heat exchange area of the air preheater 4: 500 m 2

[0065] The gas calorific value used for the hot blast stove burning: 2800 kJ / m 3

[0066] The hot blast temperature after being heated by the hot blast stove: 1250℃.

[0067] The preferred embodiments of the application have been described above in detail. It should be understood that modifications and variations to the preferred embodiments could be made by those skilled in the art in light of the teachings above. It is therefore contemplated that the application can encompass other variations and modifications that fall within the scope of the claims.

Claims

1. A hot blast stove combustion air and gas preheating system comprising a smelt reduction furnace, a fume hood, a cyclone dust collector, an air preheater, a dust collector, a combustion air fan, a hot blast stove, characterized by, The melting reduction furnace is sequentially connected with a waste gas cover, a cyclone dust collector, an air preheater, a dust collector and a hot blast furnace; the combustion-supporting fan is sequentially connected with the air preheater and the hot blast furnace; the air preheater is used for heating combustion-supporting air by using high-temperature coal gas from the cyclone dust collector.

2. A hot blast stove combustion air and gas preheating system according to claim 1, characterized in that, The air preheater is of a cylindrical structure, comprising an outer shell, a duct and an end plate, both ends of the inner part of the outer shell are fixedly provided with the end plate, and a plurality of ducts are uniformly arranged on the end plate; one end of the air preheater is provided with a gas inlet, and the side wall is provided with an air outlet; the other end is provided with a gas outlet, and the side wall is provided with an air inlet; high-temperature gas flows in the duct, combustion-supporting air flows between the outer shell and the duct, and the combustion-supporting air and the high-temperature gas flow countercurrently.

3. A hot blast stove combustion air and gas preheating system according to any one of claims 1 or 2, characterised in that, The outer shell, the duct and the end plate of the air preheater are made of 310S; the outer shell is provided with internal and / or external thermal insulation.

4. A hot blast stove combustion air and gas preheating system according to claim 1, characterized in that, The dust collector is a bag filter, and the filter bag is made of one of a cloth bag, a ceramic filter bag and a stainless steel wire filter bag.

5. A hot blast stove combustion air and gas preheating system according to claim 1, characterized in that, The dust collector inlet is connected with the outlet of the gas pressurizing machine, or the dust collector outlet is connected with the outlet of the gas pressurizing machine; the gas pressurizing machine inlet is connected with the clean gas pipeline, and part of the clean gas is mixed to adjust the temperature of the gas entering the hot blast furnace.

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