Blast furnace environment-friendly damping-down method based on dry coal gas dust removal system

Abstract

The invention discloses a blast furnace environment-friendly damping-down method based on a dry-method coal gas dust removal system. The blast furnace environment-friendly damping-down method comprises the steps that the air inlet pressure of a blast furnace is reduced to 200 KPa; opening a clean gas outlet of each cloth bag type dust collector, and closing the TRT; only hot air is conveyed to the blast furnace, and when the air inlet pressure of the blast furnace is gradually reduced to 60 KPa, steam is introduced into the furnace top of the blast furnace; opening a clean gas blowback port of each cloth bag type dust collector, closing a clean gas outlet of each cloth bag type dust collector, opening a raw gas port and a diffusion port of each cloth bag type dust collector, closing an air inlet of the blast furnace, and starting damping down of the blast furnace; according to the method, equipment transformation investment is not needed, damping-down is conducted through a dry-method gas dust removal equipment system widely applied to a modern iron-making blast furnace, and blast furnace damping-down furnace top gas dust removal and safe recovery can be achieved.

Description

Technical Field

[0001] The invention belongs to the field of blast furnace environmental protection wind-off, and in particular relates to a blast furnace environmental protection wind-off method based on a dry gas dust removal system. Background Art

[0002] The production model of modern iron-making blast furnaces is continuous and pursues an environmentally friendly production model. Therefore, the pollutant emission control in the production process is very strict. As an important by-product in the smelting process, coal gas needs to be continuously produced in a sealed environment. It is not allowed to be released in normal production and must be sent to users after dust removal. However, production needs to be interrupted when the blast furnace is shut down. Therefore, the blast furnace gas system needs to be isolated from other gas systems, and the coal gas needs to be released from the top of the blast furnace because the coal gas contains a large amount of dust, which can easily cause environmental pollution.

[0003] In order to cope with the impact of blast furnace gas cutting process on the surrounding environment, the existing technology generally adopts the top gas injection process, with a single 2000m 3 The investment cost for the transformation of a blast furnace is about 1 million yuan. In the prior art, the gas recovery process is filtered by a dust collector and then sent to a low-pressure gas network with an operating pressure of 10-15KPa. Due to the resistance formed by the network pressure and considering the safety of the recovered gas, 100% recovery cannot be achieved. The top pressure is reduced to about 2.0KPa, that is, the top gas recovery is stopped when the top pressure is reduced to 2KPa due to consideration of the safety of the recovered gas. In the prior art, when the top pressure is reduced to 2KPa, the top gas recovery is stopped and released. During the release period, slight smoke and dust still emerges in the prior art. At the same time, due to the low frequency of large-scale blast furnace shutdowns, the top shutdown gas recovery system equipment does not operate for a long time, and is in a high-corrosion and high-dust environment. The failure rate of the shutdown gas recovery equipment is relatively high, and the application effect is not good. Summary of the invention

[0004] The purpose of the present invention is to provide a blast furnace environmental protection wind-off method based on a dry gas dust removal system to solve the problems of high investment cost for transformation of the prior art, high equipment failure rate and poor application effect.

[0005] The present invention adopts the following technical scheme: a blast furnace environmental protection wind-off method based on a dry gas dust removal system, comprising:

[0006] Step 1: Discharge the slag and iron in the blast furnace;

[0007] Step 2: When the blast furnace top temperature is less than 200°C, reduce the blast furnace inlet air pressure to 200KPa;

[0008] Step 3: When the furnace top pressure of the blast furnace drops to 90KPa, open the clean gas outlets of each bag-type dust collector, and close the TRT so that the gas generated by the blast furnace passes through each bag-type dust collector and then passes through the clean gas outlets of each bag-type dust collector and is transported to the low-pressure gas pipeline network through the pressure regulating valve group;

[0009] Step 4: Close the air mixing valve group for adjusting the inlet air temperature, and only deliver hot air to the blast furnace, and gradually reduce the inlet air pressure of the blast furnace to 60KPa, and then introduce steam to the top of the blast furnace;

[0010] Step 5: Open the clean gas backflush port of each bag-type dust collector to release the gas in each bag-type dust collector;

[0011] Step 6: Close the clean gas outlet of each bag-type dust collector and disconnect the connection between each bag-type dust collector and the low-pressure gas pipeline network;

[0012] Step 7: When the air inlet pressure of the blast furnace is gradually reduced to 30KPa, the raw gas inlet and the venting port of each bag-type dust collector are opened, and nitrogen is introduced into each bag-type dust collector through the raw gas inlet of each bag-type dust collector, so that each bag-type dust collector maintains a positive pressure and prevents air from entering each bag-type dust collector from the venting port of each bag-type dust collector;

[0013] Step 8: When the air inlet pressure of the blast furnace is reduced to 10KPa, the air inlet of the blast furnace is closed and the blast furnace begins to shut down;

[0014] Step 9: When the blast furnace top pressure is less than 1KPa, open the top to release it.

[0015] Furthermore, it also includes:

[0016] Step 10: Close the inlet of the gravity dust collector between the blast furnace and the bag filter;

[0017] Step 11: Close the clean gas backflush port of each bag filter;

[0018] Step 12: Close the vents of some bag-type dust collectors and ensure that the vents of at least two bag-type dust collectors remain open, so that nitrogen is discharged through the vents of the bag-type dust collectors.

[0019] Furthermore, the clean gas outlet of each bag-type dust collector is connected to the clean gas main through a pipeline, and the clean gas main is connected to the low-pressure gas pipeline network.

[0020] Furthermore, the clean gas backflush port of each bag-type dust collector is connected to the clean gas backflush main pipe through a pipeline. A high-position relief valve is installed at one end of the clean gas backflush main pipe, and the other end is connected to the low-pressure gas pipeline network.

[0021] Furthermore, the raw gas outlet of each bag-type dust collector is connected to the raw gas main through a pipeline. One end of the raw gas main is connected to the gas outlet of the gravity dust collector, and the other end is equipped with a raw gas main vent valve and a nitrogen purge valve.

[0022] Furthermore, the dry gas dust removal system includes:

[0023] A blower, the outlet of which is connected to the inlet of the hot blast furnace;

[0024] The blast furnace has an air inlet connected to the outlet of the air mixing chamber; the inlet of the air mixing chamber is connected to the outlet of the blower and the outlet of the hot blast stove respectively, and the air mixing chamber is used to mix the hot air from the hot blast stove with the cold air from the blower and then transport them to the blast furnace after temperature adjustment;

[0025] A gravity dust collector, the inlet of which is connected to the gas outlet of the blast furnace;

[0026] The bag-type dust collector has a raw gas outlet connected to the gas outlet of the gravity dust collector through a raw gas main, a clean gas outlet connected to the low-pressure gas network through a clean gas main, and a clean gas backflush outlet connected to the low-pressure gas network through a clean gas backflush main; the bag-type dust collector is used to remove dust from the gas and transport it to the low-pressure gas network.

[0027] Furthermore, the clean gas main is connected to the TRT.

[0028] The beneficial effects of the present invention are:

[0029] The present invention does not require investment in equipment transformation, and can realize blast furnace top gas dust removal and safe recovery by utilizing a dry gas dust removal equipment system widely used in modern ironmaking blast furnaces for wind stop.

[0030] The present invention starts the wind-off operation when the blast furnace top temperature is less than 200° C., thus preventing the bag of the bag filter from being burned due to excessively high coal temperature during the blast furnace wind-off process.

[0031] The present invention closes the air mixing valve group and gradually reduces the air pressure of the blower to 60KPa, which can prevent the gas from flowing back into the cold air duct during the blast furnace shutdown process and causing accidents.

[0032] When the wind pressure of the blower is gradually reduced to 60 KPa, steam is introduced into the top of the blast furnace, and nitrogen is introduced into the ends of the gravity dust collector and the raw gas main pipe to ensure positive pressure of the blast furnace top, the gravity dust collector and the bag-type dust collector to prevent gas accidents caused by negative pressure inhalation of air;

[0033] The present invention first opens the clean gas blowback valves Jf1-Jf6, closes the clean gas butterfly valves Dj1-Dj6, and then opens the high-level relief valve Gf. This operation can prevent the system from being pressurized due to improper operation, and at the same time ensure that the gas discharged from the high-level relief valve Gf is ignited, thereby avoiding the gas being discharged into the atmosphere and causing environmental pollution.

[0034] The present invention can avoid slag filling in the tuyere due to a sudden drop in the pressure in the blast furnace caused by excessively high pressure and air shut-off by setting step 8. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a connection diagram of the present invention. DETAILED DESCRIPTION

[0036] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0038] The present invention discloses a blast furnace environmental protection wind-off method based on a dry gas dust removal system. Figure 1 As shown, including:

[0039] Step 1: Discharge the slag and iron in the blast furnace;

[0040] Step 2: When the blast furnace top temperature is less than 200°C, reduce the blast furnace inlet air pressure to 200KPa;

[0041] Step 3: When the furnace top pressure of the blast furnace drops to 90KPa, open the clean gas outlets of each bag-type dust collector, and close the TRT so that the gas generated by the blast furnace passes through each bag-type dust collector and then passes through the clean gas outlets of each bag-type dust collector and is transported to the low-pressure gas pipeline network through the pressure regulating valve group;

[0042] Step 4: Close the air mixing valve group for adjusting the inlet air temperature, and only deliver hot air to the blast furnace, and gradually reduce the inlet air pressure of the blast furnace to 60KPa, and then introduce steam to the top of the blast furnace;

[0043] Step 5: Open the clean gas backflush port of each bag-type dust collector to release the gas in each bag-type dust collector;

[0044] Step 6: Close the clean gas outlet of each bag-type dust collector and disconnect the connection between each bag-type dust collector and the low-pressure gas pipeline network;

[0045] Step 7: When the air inlet pressure of the blast furnace is gradually reduced to 30KPa, the raw gas inlet and the venting port of each bag-type dust collector are opened, and nitrogen is introduced into each bag-type dust collector through the raw gas inlet of each bag-type dust collector, so that each bag-type dust collector maintains a positive pressure and prevents air from entering each bag-type dust collector from the venting port of each bag-type dust collector;

[0046] Step 8: When the air inlet pressure of the blast furnace is reduced to 10KPa, the air inlet of the blast furnace is closed and the blast furnace begins to shut down;

[0047] Step 9: When the blast furnace top pressure is less than 1KPa, open the top to release it.

[0048] Furthermore, it also includes:

[0049] Step 10: Close the inlet of the gravity dust collector between the blast furnace and the bag filter;

[0050] Step 11: Close the clean gas backflush port of each bag filter;

[0051] Step 12: Close the vents of some bag-type dust collectors and ensure that the vents of at least two bag-type dust collectors remain open, so that nitrogen is discharged through the vents of the bag-type dust collectors.

[0052] Furthermore, the clean gas outlet of each bag-type dust collector is connected to the clean gas main through a pipeline, and the clean gas main is connected to the low-pressure gas pipeline network.

[0053] Furthermore, the clean gas backflush port of each bag-type dust collector is connected to the clean gas backflush main pipe through a pipeline. A high-position relief valve is installed at one end of the clean gas backflush main pipe, and the other end is connected to the low-pressure gas pipeline network.

[0054] Furthermore, the raw gas outlet of each bag-type dust collector is connected to the raw gas main through a pipeline. One end of the raw gas main is connected to the gas outlet of the gravity dust collector, and the other end is equipped with a raw gas main vent valve and a nitrogen purge valve.

[0055] Furthermore, the dry gas dust removal system includes:

[0056] A blower, the outlet of which is connected to the inlet of the hot blast furnace;

[0057] The blast furnace has an air inlet connected to the outlet of the air mixing chamber; the inlet of the air mixing chamber is connected to the outlet of the blower and the outlet of the hot blast stove respectively, and the air mixing chamber is used to mix the hot air from the hot blast stove with the cold air from the blower and then transport them to the blast furnace after temperature adjustment;

[0058] A gravity dust collector, the inlet of which is connected to the gas outlet of the blast furnace;

[0059] The bag-type dust collector has a raw gas outlet connected to the gas outlet of the gravity dust collector through a raw gas main, a clean gas outlet connected to the low-pressure gas network through a clean gas main, and a clean gas backflush outlet connected to the low-pressure gas network through a clean gas backflush main; the bag-type dust collector is used to remove dust from the gas and transport it to the low-pressure gas network.

[0060] Furthermore, the clean gas main is connected to the TRT.

[0061] The high-temperature hot air in step 2 of the present invention is formed by high-pressure air provided by a blower and heated by a hot blast furnace. The blower sends the high-pressure air into the hot blast furnace through a pipeline for heating, and then sends it into the blast furnace. In the blast furnace, the high-temperature hot air reacts with coke and iron raw materials. The coke and iron raw materials are loaded from the top of the blast furnace and move downward. The generated molten iron and slag are discharged from the iron mouth of the blast furnace. The coal gas generated after the high-temperature hot air enters the blast furnace moves from bottom to top. In normal production, the coal gas passes through a bag-type dust collector and enters the TRT to generate electricity. Finally, it is sent to the low-pressure gas pipeline network for users to use. When the blast furnace needs to be shut down, the coal gas is sent to the low-pressure gas pipeline network for users to use through a pressure regulating valve group.

[0062] The gravity dust collector in the present invention separates large particles of dust from coal gas under the action of gravity, while the bag-type dust collector is generally set in corresponding quantity according to the amount of coal gas; after the bag-type dust collector has been running for a certain period of time, the ash film adhered to the bag becomes thicker and the system resistance increases. In order to ensure the stable operation of the coal gas dust collector, the bag needs to be backblown and cleaned.

[0063] Example 1

[0064] There are 6 bag-type dust collectors, 1 blower station and 3 hot blast furnaces around the blast furnace of a certain steel plant; among them, the clean gas back-blow ports of the 6 bag-type dust collectors are provided with 6 clean gas back-blow valves, which are numbered Jf1-Jf6; the raw gas ports of the 6 bag-type dust collectors are provided with 6 raw gas butterfly valves, which are numbered Dh1-Dh6; the vent ports of the 6 bag-type dust collectors are provided with 6 vent valves, which are numbered f1-f6; the clean gas outlets of the 6 bag-type dust collectors are provided with 6 clean gas butterfly valves, which are numbered Dj1-Dj6.

[0065] The blast furnace of a steel plant needs to be shut down. The shut down method of the present invention is used for operation. The specific process is as follows:

[0066] Step 1: Before the blast furnace is shut down, put all the slag and iron in the furnace;

[0067] Step 2: Control the box temperature of the blast furnace to less than 200°C and reduce the air inlet pressure of the blast furnace to 200KPa;

[0068] Step 3: When the furnace top pressure of the blast furnace drops to about 90KPa, close the TRT and exit and open the pressure regulating valve group, so that the gas generated by the blast furnace passes through each bag-type dust collector and then passes through the clean gas outlet of each bag-type dust collector and is transported to the low-pressure gas pipeline network through the pressure regulating valve group;

[0069] Step 4: Gradually reduce the air pressure of the blower to 100KPa and close the air mixing valve group, only deliver hot air to the blast furnace, and when the air inlet pressure of the blast furnace drops to 60KPa, introduce steam to the top of the blast furnace;

[0070] Step 5: Open the clean gas backflush port of each bag-type dust collector through the clean gas backflush valve Jf1-Jf6, so that the gas in each bag-type dust collector enters the clean gas backflush main pipe for release, and open the high-position release valve Gf of the gas backflush main pipe;

[0071] Step 6: Close the clean gas outlet of each bag-type dust collector through the clean gas butterfly valve Dj1-Dj6, and disconnect each bag-type dust collector from the low-pressure gas pipeline network;

[0072] Step 7: When the air inlet pressure of the blast furnace is reduced to 30KPa, open the raw gas butterfly valve Dj1-Dj6 of the raw gas outlet of each bag-type dust collector, and open the vent valve f1-f6 of the vent outlet of each bag-type dust collector, and then introduce nitrogen into each bag-type dust collector through the raw gas outlet of each bag-type dust collector, so that each bag-type dust collector maintains a positive pressure and prevents air from entering each bag-type dust collector from the vent outlet of each bag-type dust collector; in addition, nitrogen is introduced into the gravity dust collector through the nitrogen purge valve of the gravity dust collector, and the operation of introducing nitrogen into each bag-type dust collector is coordinated, so that each bag-type dust collector, the blast furnace top, the gravity dust collector, and the raw gas main are all maintained at a positive pressure.

[0073] Step 8: When the air inlet pressure of the blast furnace is reduced to 10KPa, close the cold air valve and the hot air valve, and then close the air inlet of the blast furnace, and the blast furnace begins to shut down;

[0074] Step 9: Observe the furnace top pressure after 5 minutes of wind stop. When the furnace top pressure is less than 1KPa, open the furnace top for release.

[0075] Step 10: Close the gravity shutoff valve of the gravity dust collector;

[0076] Step 11: Close the clean gas back-blowing valves Jf1-Jf6 of the bag filter;

[0077] Step 12: Close the high-level vent valve Gf, open the vent valve f1 of 1# bag-type dust collector and the vent valve f2 of 2# bag-type dust collector, as well as the raw gas butterfly valve Dh1 of 1# bag-type dust collector and the raw gas butterfly valve Dh2 of 2# bag-type dust collector, close the vent valves f3-f6 of 4 bag-type dust collectors and the raw gas butterfly valves Dh3-Dh6 of 4 bag-type dust collectors, open the gravity DN400 vent valve, and the blast furnace wind shutdown is completed.

[0078] After the wind-down is completed, close the steam valve on the furnace top, the nitrogen purge valve on the gravity dust collector and the raw gas main, and open the backflow wind-down valve appropriately as needed.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A blast furnace environmental protection wind-off method based on a dry gas dust removal system, characterized in that: include: Step 1: Discharge the slag and iron in the blast furnace; Step 2: When the blast furnace top temperature is less than 200°C, reduce the blast furnace inlet air pressure to 200KPa; Step 3: When the furnace top pressure of the blast furnace drops to 90KPa, open the clean gas outlets of each bag-type dust collector, and close the TRT so that the gas generated by the blast furnace passes through each bag-type dust collector and then passes through the clean gas outlets of each bag-type dust collector and is transported to the low-pressure gas pipeline network through the pressure regulating valve group; Step 4: Close the air mixing valve group for adjusting the inlet air temperature, and only deliver hot air to the blast furnace, and gradually reduce the inlet air pressure of the blast furnace to 60KPa, and then introduce steam to the top of the blast furnace; Step 5: Open the clean gas backflush port of each bag-type dust collector to release the gas in each bag-type dust collector; Step 6: Close the clean gas outlet of each bag-type dust collector and disconnect the connection between each bag-type dust collector and the low-pressure gas pipeline network; Step 7: When the air inlet pressure of the blast furnace is gradually reduced to 30KPa, the raw gas inlet and the venting port of each bag-type dust collector are opened, and nitrogen is introduced into each bag-type dust collector through the raw gas inlet of each bag-type dust collector, so that each bag-type dust collector maintains a positive pressure and prevents air from entering each bag-type dust collector from the venting port of each bag-type dust collector; Step 8: When the air inlet pressure of the blast furnace is reduced to 10KPa, the air inlet of the blast furnace is closed and the blast furnace begins to shut down; Step 9: When the blast furnace top pressure is less than 1KPa, open the top to release it.

2. The blast furnace environmental protection wind-off method based on the dry gas dust removal system according to claim 1 is characterized in that: Also includes: Step 10: Close the inlet of the gravity dust collector between the blast furnace and the bag filter; Step 11: Close the clean gas backflush port of each bag filter; Step 12: Close the vents of some bag-type dust collectors and ensure that the vents of at least two bag-type dust collectors remain open, so that nitrogen is discharged through the vents of the bag-type dust collectors.

3. The blast furnace environmental protection wind-off method based on the dry gas dust removal system according to claim 1 is characterized in that: The clean gas outlet of each bag-type dust collector is connected to the clean gas main through a pipeline, and the clean gas main is connected to the low-pressure gas pipeline network.

4. The blast furnace environmental protection wind-off method based on the dry gas dust removal system according to claim 1 is characterized in that: The clean gas backflush ports of each bag-type dust collector are connected to the clean gas backflush main pipe through a pipeline. A high-position relief valve is installed at one end of the clean gas backflush main pipe, and the other end is connected to the low-pressure gas pipeline network.

5. The blast furnace environmental protection wind-off method based on the dry gas dust removal system according to claim 1 is characterized in that: The raw gas outlet of each of the bag-type dust collectors is connected to the raw gas main through a pipeline. One end of the raw gas main is connected to the gas outlet of the gravity dust collector, and the other end is equipped with a raw gas main release valve and a nitrogen purge valve. The gravity dust collector is also used to introduce nitrogen into it, and cooperate with the operation of introducing nitrogen into each bag-type dust collector, so that each bag-type dust collector, blast furnace top and gravity dust collector maintains positive pressure.

6. A blast furnace environmental protection wind-off method based on a dry gas dust removal system according to claim 5, characterized in that: The dry gas dust removal system comprises: A blower, the outlet of which is connected to the inlet of the hot blast furnace; A blast furnace, whose air inlet is connected to the outlet of a mixing chamber; the inlet of the mixing chamber is respectively connected to the outlet of the blower and the outlet of the hot blast stove, and the mixing chamber is used to mix the hot air from the hot blast stove with the cold air from the blower and then transport them to the blast furnace after temperature adjustment; A gravity dust collector, the inlet of which is connected to the gas outlet of the blast furnace; A bag-type dust collector, whose raw gas outlet is connected to the gas outlet of the gravity dust collector through the raw gas main, whose clean gas outlet is connected to the low-pressure gas network through the clean gas main, and whose clean gas backflush outlet is connected to the low-pressure gas network through the clean gas backflush main; the bag-type dust collector is used to remove dust from the gas and transport it to the low-pressure gas network.

7. A blast furnace environmental protection wind-off method based on a dry gas dust removal system according to claim 6, characterized in that: The clean gas main is connected to the TRT.

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