Air supply method of hot blast stove during blowing-out period of blast furnace

Abstract

The invention relates to an air supply method of a hot blast stove during blowing out of a blast furnace. The air supply method comprises the following steps: step 1, placing a backflow valve and an upper blind plate of a tuyere in a state of being disconnected from an air supply system of the blast furnace; 2, the sequential circulation process of furnace burning, furnace burning and air supply conversion, air supply and furnace burning is conducted, when the temperature of the arch crown of the hot blast stove and the temperature of the arch crown of the preheating furnace are reduced to the first preset temperature, furnace burning operation is conducted, and when the temperature of the hot blast stove and the temperature of the arch crown reach the second preset temperature and the temperature of waste gas does not exceed the third preset temperature, furnace burning and air supply conversion operation is conducted; air supply: opening the vent valve at a preset opening degree, opening a hot blast valve and a cold blast valve of each hot blast stove to supply air, and enabling cold air to enter the hot blast stove through a cold air pipeline and the cold blast valve, then to pass through the hot blast valve, a hot air pipeline and a backflow valve, and finally to enter atmosphere through a backflow chimney. Natural air is adopted for blowing in the blowing-out period of the blast furnace, coal gas for burning the furnace is saved, and the cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of blast furnace ironmaking, and in particular to an air supply method for a hot blast furnace during a blast furnace shutdown period. Background Art

[0002] Modern blast furnace ironmaking equipment is equipped with a hot blast furnace, which provides the hot air required for blast furnace smelting. The hot blast furnace is performed in three parts: combustion, air supply, and conversion between combustion and air supply. When the blast furnace is in normal production, the cold air blown out from the blower passes through the cold air duct and then enters the hot blast furnace. The cold air brings the heat of the lattice bricks in the heat storage chamber of the hot blast furnace (heat stored during the combustion of the hot blast furnace) into the hot air duct through convection, radiation and other methods, and finally enters the blast furnace for combustion reaction. When the blast furnace is shut down for overhaul, if the hot blast furnace is not cooled for maintenance, it is still necessary to perform the three operations of combustion, air supply, and conversion between combustion and air supply to avoid damage to the refractory materials in the hot blast furnace due to drastic temperature fluctuations. Figure 3 As shown, the method commonly used in the prior art is: connect a temporary pipeline at the manhole of the cold air pipeline, use an axial flow fan to blow in cold air, pass through the temporary pipeline, pass through the cold air valve to enter the hot air furnace, and then pass through the hot air valve and the hot air pipeline to enter the backflow valve to enter the backflow chimney and enter the atmosphere to complete the air supply process. With this method, the operation of the axial flow fan consumes electricity. In addition, after about 4 hours of air supply by this method, the temperature of the heat storage chamber decreases, and the hot air furnace needs to be converted to combustion operation. The above operation needs to be repeated 4 to 5 times a day, and gas needs to be consumed during the combustion period, resulting in increased costs. Summary of the invention

[0003] According to the technical problem raised above, a method for supplying air to a hot blast stove during a blast furnace shutdown is provided.

[0004] The technical means adopted by the present invention are as follows:

[0005] A method for supplying air to a hot blast stove during a blast furnace shutdown period, comprising the following steps:

[0006] Step 1: disconnect the backflow valve and the upper blind plate of the tuyere from the blast furnace air supply system;

[0007] Step 2, furnace burning → furnace burning and air supply conversion → air supply → furnace burning cycle process, wherein,

[0008] When the temperature of the dome of the hot blast furnace and the preheating furnace drops to the first preset temperature, the furnace burning operation is carried out. The furnace burning operation steps are: open the exhaust valve; open the flue valve; close the exhaust valve; open the gas combustion valve (and close the gas release valve at the same time); open the nitrogen purge valve; close the nitrogen purge valve; open the air combustion valve; open the gas shut-off valve; open the air regulating valve slightly; open the gas regulating valve slightly; open the gas regulating valve and the air regulating valve widely, and close the combustion air release valve at the same time, and adjust the air-fuel ratio so that the hot blast furnace can achieve reasonable combustion;

[0009] When the temperature of the hot blast furnace and the dome reaches the second preset temperature, and the exhaust gas temperature does not exceed the third preset temperature, the furnace burning and air supply switching operation is performed: close the gas regulating valve; close the air regulating valve; close the gas shut-off valve; close the air combustion valve; open the nitrogen purge valve; close the nitrogen purge valve; close the gas combustion valve, and open the gas release valve at the same time; close the flue valve;

[0010] Air supply: The vent valve is opened at a preset opening, and the hot air valve and cold air valve of each hot air furnace are opened to supply air. The cold air passes through the cold air duct, enters the hot air furnace through the cold air valve, and then passes through the hot air valve, hot air duct, backflow valve, and finally enters the atmosphere through the backflow chimney.

[0011] Furthermore, the first preset temperature is 900°C.

[0012] Furthermore, the second preset temperature is 1200-1350°C, and the third preset temperature is 330°C.

[0013] Furthermore, when air is supplied, the opening degree of the air release valve is 50%.

[0014] Compared with the prior art, the present invention has the following advantages: the air supply method for the hot blast furnace during the blast furnace shutdown period disclosed in the present invention does not need to use an axial flow fan for air supply, but adopts natural wind for air supply, and the air supply time is extended by natural suction. The three operations of air supply, combustion and air supply conversion only need to be performed once a day, which saves coal gas for burning the furnace and reduces costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0016] Figure 1 It is a schematic diagram of the process flow of the present invention.

[0017] Figure 2 This is a schematic diagram of the hot blast furnace firing process flow.

[0018] Figure 3 It is a schematic diagram of the prior art process.

[0019] Figure 4 This is a schematic diagram of the specific pipeline valve installation of the present invention. DETAILED DESCRIPTION

[0020] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0021] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0023] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, the numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0024] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0025] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0026] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0027] like Figure 1 , Figure 2 , Figure 4 As shown, the embodiment of the present invention discloses a method for supplying air to a hot blast stove during a blast furnace shutdown, comprising the following steps:

[0028] Step 1: disconnect the backflow valve and the upper blind plate of the tuyere from the blast furnace air supply system;

[0029] Step 2, furnace burning → furnace burning and air supply conversion → air supply → furnace burning cycle process, wherein,

[0030] When the temperature of the dome of the hot blast furnace and the preheating furnace drops to the first preset temperature, the furnace burning operation is carried out. The furnace burning operation steps are: open the exhaust valve; open the flue valve; close the exhaust valve; open the gas combustion valve (and close the gas release valve at the same time); open the nitrogen purge valve; close the nitrogen purge valve; open the air combustion valve; open the gas shut-off valve; open the air regulating valve slightly; open the gas regulating valve slightly; open the gas regulating valve and the air regulating valve widely, and close the combustion air release valve at the same time, and adjust the air-fuel ratio so that the hot blast furnace can achieve reasonable combustion;

[0031] When the temperature of the hot blast furnace and the dome reaches the second preset temperature, and the exhaust gas temperature does not exceed the third preset temperature, the furnace burning and air supply switching operation is performed: close the gas regulating valve; close the air regulating valve; close the gas shut-off valve; close the air combustion valve; open the nitrogen purge valve; close the nitrogen purge valve; close the gas combustion valve, and open the gas release valve at the same time; close the flue valve;

[0032] Air supply: The vent valve is opened at a preset opening, and the hot air valve and cold air valve of each hot air furnace are opened to supply air. The cold air passes through the cold air duct, enters the hot air furnace through the cold air valve, and then passes through the hot air valve, hot air duct, backflow valve, and finally enters the atmosphere through the backflow chimney.

[0033] The function of the air mixing valve is to add a certain amount of cold air into the hot air duct to keep the air supply temperature constant. The cold air gate is used to cut off the connection between the blast furnace and the cold air duct during the wind stop period to prevent the blast furnace gas from entering the cold air duct and causing safety accidents.

[0034] The above operation completes a cycle in 24 hours: the burning time of each furnace is 1 hour, totaling 3 to 4 hours, the time for the three hot air furnaces to supply air at the same time is about 16 hours, and the rest is the time for switching between burning and supplying air.

[0035] Furthermore, the first preset temperature is 900°C.

[0036] Furthermore, the second preset temperature is 1200-1350°C, and the third preset temperature is 330°C.

[0037] Furthermore, when air is supplied, the opening degree of the air release valve is 50%.

[0038] This device is used for the air supply operation of the hot blast furnace during the shutdown of the new No. 2 blast furnace of Benxi Iron and Steel Beiying Iron and Steel Plant. It uses natural suction to save the power consumption of the axial flow fan. At the same time, the furnace only needs to be fired once a day, reducing three times of firing, saving coal gas for firing and reducing ironmaking costs.

[0039] Finally, it should be noted that 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for supplying air to a hot blast stove during a blast furnace shutdown, characterized in that: The steps include: Step 1: disconnect the backflow valve and the upper blind plate of the tuyere from the blast furnace air supply system; Step 2, furnace burning → furnace burning and air supply conversion → air supply → furnace burning cycle process, wherein, When the temperature of the dome of the hot blast furnace and the preheating furnace drops to the first preset temperature, the furnace burning operation is carried out. The furnace burning operation steps are: open the exhaust valve; open the flue valve; close the exhaust valve; open the gas combustion valve and close the gas release valve at the same time; open the nitrogen purge valve; close the nitrogen purge valve; open the air combustion valve; open the gas shut-off valve; open the air regulating valve slightly; open the gas regulating valve slightly; open the gas regulating valve and the air regulating valve widely, and close the combustion air release valve at the same time, and adjust the air-fuel ratio so that the hot blast furnace can achieve reasonable combustion; When the temperature of the hot blast furnace and the dome reaches the second preset temperature, and the exhaust gas temperature does not exceed the third preset temperature, the furnace burning and air supply switching operation is performed: close the gas regulating valve; close the air regulating valve; close the gas shut-off valve; close the air combustion valve; open the nitrogen purge valve; close the nitrogen purge valve; close the gas combustion valve, and open the gas release valve at the same time; close the flue valve; Air supply: The vent valve is opened at a preset opening, and the hot air valve and cold air valve of each hot air furnace are opened to supply air. The cold air passes through the cold air duct, enters the hot air furnace through the cold air valve, and then passes through the hot air valve, hot air duct, backflow valve, and finally enters the atmosphere through the backflow chimney.

2. The air supply method for a hot blast stove during blast furnace shutdown according to claim 1, characterized in that: The first preset temperature is 900°C.

3. The air supply method for a hot blast stove during blast furnace shutdown according to claim 1, characterized in that: The second preset temperature is 1200-1350°C, and the third preset temperature is 330°C.

4. The air supply method for a hot blast stove during blast furnace shutdown according to claim 1, characterized in that: When air is supplied, the opening degree of the vent valve is 50%.

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