Hot blast stove with preheating air return system

Abstract

The utility model discloses a hot-blast stove with a preheating air return system. The hot-blast stove comprises a burner and a hot-blast stove body, the combustor is connected with a fuel gas assembly and a combustion-supporting air assembly; the combustion-supporting air assembly comprises a combustion-supporting fan, a combustion-supporting air pipeline and a preheating air return pipeline; an air inlet of the combustion fan comprises a normal-temperature air inlet and a return air inlet; one end of the preheating air return pipeline is connected with the hot-blast stove body, and the other end is connected with the air return inlet; and an air outlet of the combustion-supporting fan is connected with the combustor through a combustion-supporting air pipeline. After hot smoke returned through the preheating air return pipeline is mixed with low-temperature air, the temperature of combustion-supporting air fed into the combustor through the combustion-supporting fan is far higher than that of the low-temperature air (30-50 DEG C), combustion can be more stable through the combustion-supporting air with the higher temperature, the flameout frequency in the operation process is reduced, and the reliability of the whole system is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of blast furnaces, in particular to a hot blast furnace with a preheating return air system. Background Art

[0002] The gas hot blast furnace system is generally composed of a combustion valve group, a matching fan and a hot blast furnace body, etc. Natural gas, industrial by-product gas, generator tail gas, etc. can all be used as gas fuel, and normal temperature air is used as combustion air and secondary air.

[0003] Existing deficiencies: Iron and steel enterprises often use blast furnace gas as the combustion gas source for iron ore drying. The calorific value of blast furnace gas is low (about 600-750 kcal), and the combustion is unstable, especially in the north in winter when the temperature is low (the temperature of the air for combustion is also low), which will cause ignition difficulties and easy flameout during combustion, affecting the stability of the entire drying system. Summary of the invention

[0004] The problem to be solved by the present invention is to propose an improvement plan or a replacement plan for the shortcomings of the above-mentioned prior art, especially an improvement for increasing the inlet temperature of the burner, and this improvement plan not only does not increase energy consumption, but also has a warming effect.

[0005] To solve the above problems, the solution adopted by the utility model is as follows: a hot blast furnace with a preheating return air system, characterized in that it includes a burner and a hot blast furnace body; the burner is connected with a gas component and a combustion-supporting air component; the combustion-supporting air component includes a combustion-supporting fan, a combustion-supporting air duct and a preheating return air duct; the air inlet of the combustion-supporting fan includes a normal temperature air inlet and a return air inlet; one end of the preheating return air duct is connected to the hot blast furnace body, and the other end is connected to the return air inlet; the air outlet of the combustion-supporting fan is connected to the burner through the combustion-supporting air duct.

[0006] Furthermore, the hot blast furnace with a preheating return air system is characterized in that a hot blast furnace interlayer is provided on the furnace wall of the hot blast furnace body, and a plurality of holes are evenly arranged between the hot blast furnace interlayer and the hot blast furnace body; the preheating return air duct is connected to the hot blast furnace interlayer to guide part of the hot flue gas into the combustion-supporting fan to mix with normal temperature air.

[0007] Furthermore, the hot blast furnace with a preheating return air system is characterized in that a secondary fan is provided at the front end of the hot blast furnace body, and the secondary fan is connected to the hot blast furnace interlayer to form a positive pressure in the hot blast furnace body.

[0008] The technical effects of the utility model are as follows: a path of hot flue gas (with a temperature of up to 150°C) is drawn from the interlayer of the hot blast furnace body and sent back to the air inlet of the combustion-supporting fan, where it is mixed with normal temperature air and then sent to the burner by the combustion-supporting fan to participate in combustion.

[0009] After the hot flue gas is returned and mixed with the low-temperature air, the temperature of the combustion air sent into the burner by the combustion-supporting fan is much higher than that of the low-temperature air (up to 30-50°C). The higher temperature of the combustion-supporting air can ensure more stable combustion, reduce the frequency of flameout during operation, and improve the reliability of the entire system. At the same time, due to the increase in the intake temperature, it is easier to heat up, and the temperature that can be reached is higher, or less gas is used under the same temperature conditions, which saves more energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram of the hot air furnace structure with a preheating return air system.

[0011] Figure 2 Side view of a hot air furnace with a preheated return air system.

[0012] Figure 3 This is a cross-sectional view of a hot air furnace with a preheated return air system.

[0013] Among them, 1 is the burner, 2 is the hot blast furnace body, 3 is the combustion-supporting fan, 4 is the preheating return air duct, 5 is the combustion-supporting air duct, 6 is the hot blast furnace interlayer, 7 is the secondary fan, 31 is the return air inlet, and 32 is the normal temperature air inlet. DETAILED DESCRIPTION

[0014] The utility model is further described in detail below in conjunction with the accompanying drawings.

[0015] Embodiment: A hot blast furnace with a preheating return air system comprises a burner and a hot blast furnace body; the burner is connected with a gas component and a combustion-supporting air component; the combustion-supporting air component comprises a combustion-supporting fan, a combustion-supporting air duct and a preheating return air duct; the air inlet of the combustion-supporting fan comprises a normal temperature air inlet and a return air inlet; one end of the preheating return air duct is connected to the hot blast furnace body, and the other end is connected to the return air inlet; the air outlet of the combustion-supporting fan is connected to the burner through the combustion-supporting air duct. The furnace wall of the hot blast furnace body is provided with a hot blast furnace interlayer, and the waste smoke of the hot blast furnace body passes through the hot blast furnace interlayer and is discharged; the preheating return air duct is connected to the hot blast furnace interlayer.

[0016] By setting a hot blast furnace interlayer in the hot blast furnace wall, the waste flue gas is used to keep the hot blast furnace body warm. At the same time, a path of hot flue gas (temperature can reach 150°C) is led back to the air inlet of the combustion-supporting fan in the hot blast furnace interlayer, mixed with normal temperature air, and then sent to the burner by the combustion-supporting fan to participate in combustion. The temperature of the combustion-supporting air after mixing can reach about 40 degrees. Compared with normal temperature air, especially normal temperature air in northern winter, the intake air temperature is greatly increased, ensuring more stable combustion, reducing the frequency of flameout during operation, and improving the reliability of the entire system.

[0017] The secondary air injected by the secondary air fan 7 passes through the hot blast furnace interlayer. Due to the high temperature of the hot air in the hot blast furnace body 2, the temperature of the secondary air in the hot blast furnace interlayer can reach 150 degrees due to heat transfer. Finally, part of the hot air in the hot blast furnace interlayer is drawn into the combustion-supporting air fan through the preheating return air duct 4, mixed with the normal temperature air, and provides oxygen with suitable temperature for the burner 1.

[0018] The secondary air blower 7 is connected to the hot blast furnace interlayer, and multiple holes are opened on the outer side of the hot blast furnace body to allow the secondary air to flow in, forming a positive pressure in the hot blast furnace body. The hot flue gas in the hot blast furnace body is enhanced to disturb the hot flue gas, which helps to prolong the residence time of the hot flue gas in the furnace and the vertical flue, adjust the oxygen content of the hot flue gas in the hot blast furnace body, help control the combustion and furnace temperature, and then indirectly control the boiler load, and help to inhibit the coking of the furnace.

Claims

1. A hot air furnace with a preheating return air system, characterized in that: The invention comprises a burner (1) and a hot blast furnace body (2); the burner (1) is connected to a gas component and a combustion-supporting air component; the combustion-supporting air component comprises a combustion-supporting air fan (3), a combustion-supporting air duct (5) and a preheating return air duct (4); the air inlet of the combustion-supporting air fan (3) comprises a normal temperature air inlet (32) and a return air inlet (31); one end of the preheating return air duct (4) is connected to the hot blast furnace body (2), and the other end is connected to the return air inlet (31); the air outlet of the combustion-supporting air fan (3) is connected to the burner (1) via the combustion-supporting air duct (5).

2. The hot air stove with a preheating return air system according to claim 1, characterized in that: The furnace wall of the hot blast furnace body (2) is provided with a hot blast furnace interlayer (6), and a plurality of holes are evenly arranged between the hot blast furnace interlayer (6) and the hot blast furnace body (2); the preheating return air duct (4) is connected to the hot blast furnace interlayer (6) to guide part of the hot flue gas into the combustion-supporting fan (3) to mix with the normal temperature air.

3. The hot air stove with a preheating return air system according to claim 1, characterized in that: A secondary fan (7) is provided at the front end of the hot blast furnace body (2), and the secondary fan (7) is connected to the hot blast furnace interlayer (6) to form a positive pressure in the hot blast furnace body (2).

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