KR20140043309A - Method for feeding hot gas to a shaft furnace - Google Patents

Abstract

The present invention provides a method for supplying heat gas to a furnace, in particular a blast furnace. The method comprises a bustle pipe 56 arranged to receive heat gas from a gas main part 58 and a plurality of blower pipes 18 for injecting heat gas from the bustle pipe 56 to the furnace, The blower pipe 18 is disposed around the outer circumferential surface of the furnace, and each of the blower pipes 18 has a down leg portion 39 for connecting with bustle pipes; A blowing pipe (34) for injecting the hot gas into the furnace through a tuyere disposed in the opening of the furnace shell (12); And providing a blower pipe arrangement including an elbow portion 37 disposed between the down leg portion 39 and the blower pipe 34. According to one aspect of the present invention, a laval type restriction part 40, 40 ′, 40 ″ is disposed in the blower pipe 18.

Description

Method for injecting heat gas into the furnace {METHOD FOR FEEDING HOT GAS TO A SHAFT FURNACE}

The present invention generally relates to a novel method for injecting hot gas, such as injection air, into a furnace, in particular through a plurality of tuyere stocks.

In shaft furnaces, in particular in blast furnaces, as a pressurized hot air, generally referred to as "hot blast air", hot gas is blown into the furnace for the combustion of coke, producing the CO gas required for the reduction of ores in the furnace.

Typically, a circumferential busty pipe is arranged at regular intervals in a tuyere band surrounding the outer shell of the furnace. Hot gas is injected from bustle pipes through a number of tuyere stocks that blow heat gas into the furnace. In general, the blower pipe is provided with bellows to compensate for the relative movement between the bustle pipe and the furnace, which are mainly caused by thermal expansion. Such conventional busstle pipe arrangements are known, for example, from the WO 86/05520 document.

Recently, the flow rate of hot gas into the furnace through the blower pipe is controlled by a blower provided upstream of the bustle pipe. The hot blast main injects hot gas from the blower into the bustle pipe. In order to ensure high efficiency, smooth operation, and smooth descent, it is important that all internal processes of the furnace be symmetrical. Therefore, uniform distribution of the hot gas into the furnace is essential.

It is a state of the art to achieve uniform distribution by providing tuyeres with sufficiently small diameters and sufficiently high pressure losses. However, if the flow rate of hot gas is less than the nominal flow rate of the hot blast system, a uniform distribution is no longer guaranteed since the pressure loss in the blower tube is too small than the other pressure losses in the circuit. Do not. As a result, the blower tubes disposed adjacent to the hot blast mains often have a higher flow rate than the blower tubes disposed opposite to the circumference of the hot blast mains. Furthermore, there may be a case where the blower tube is blocked or partially blocked by unreduced burden. This stagnation of content at the front of the blower tube reduces the flow rate through the blower tube. In addition, asymmetrical pressure losses in each blow pipe of the blower can be caused by inadequate adjustment of auxiliary fuel lances, which leads to premature pre-combustion of fuel in the blower. Can cause.

Non-uniform injection of heat gas into the furnace can result in non-uniform and even uncontrolled gas distribution in the furnace. The most extreme and uncontrolled phenomena are called channeling and fluidization, in which gas from a restricted area in the furnace moves directly from the blower tube to the top without reducing the ore. This results in a high gas temperature at the top which could potentially damage the device placed on top of the.

In JP 09095720A and JP 2002241818A, uniform distribution of hot gas can be achieved by having butterfly valves in individual blower tubes. These butterfly valves can be operated individually to control the flow of hot gas through each blower tube. The butterfly valve consists of a disc-shaped control member mounted on a rotating shaft disposed in the center of the hot blast passage. In the closed position, the disc shaped control member is positioned perpendicular to the flow of hot air, essentially blocking the passage of the hot air. Thereafter, the control member may be rotated 90 ° in an open position, where the control member is essentially parallel to the flow of hot air, such that the hot air can flow along the valve. In the intermediate position, the flow through the valve can be somewhat limited, thereby gaining control over the flow through each blower pipe. The disadvantage of the method is that the stability and durability of these butterfly valves may be impaired by exposure to extreme conditions in the blower tube.

Furthermore, the control method using the butterfly valves mounted on the blower pipes can be a rather burdensome control system, which allows each butterfly valve to increase or decrease the flow of hot gas through each blower pipe. This is because they must be adjusted individually.

Thus, there is a need for an improved method of ensuring a favorable and uniform flow rate through all blower tubes in the furnace and improving overall gas efficiency and thus fuel consumption.

It is an object of the present invention to provide a method for supplying heat gas to a furnace. This object is achieved by the method set forth in claim 1.

Next, preferred embodiments of the present invention are described by way of example with reference to the following associated drawings:
1 is a schematic cross-sectional view of a tuyere stock arrangement with a blower according to one embodiment of the present invention;
FIG. 2 is a schematic cross-sectional view of the Laval type restricting portion disposed in the blower pipe of FIG. 1; FIG.
3 is a schematic cross-sectional view of a blower pipe arrangement in the blower pipe according to another embodiment of the present invention;
4 is a schematic cross-sectional view of a blower pipe arrangement in a blower pipe according to another embodiment of the present invention;
5 is a schematic plan view of a hot gas distribution system for injecting hot gas into a furnace; And
Figure 6 is a graph showing the results of mass flow through individual tuyere with or without laval type restriction in the blower pipe.

The present invention provides a method for injecting hot gas into a furnace, in particular a blast furnace. The method includes a bustle pipe arranged to receive heat gas from a gas main part and a plurality of blower pipes for injecting heat gas from the bustle pipe to the furnace, the blower pipe being disposed around the outer circumferential surface of the furnace, Each of the blower pipes has a downleg section for connecting to the bustle pipe, a blower pipe for injecting the hot gas into the furnace through a tuyere disposed in the furnace shell opening, and the downleg section and the blower. And providing a blower tube arrangement comprising an elbow disposed between the pipes. According to one aspect of the invention, the method further comprises providing a Laval type restriction in each of the blower pipe.

The use of the Laval-type restriction in the blower tube makes it easier to distribute the uniform heat gas into the furnace. Of course, there is generally no need for each blower tube to have a regulation device that is responsible for the mechanical errors caused by a large number of complex mechanical components and controls them individually. The laval restrictor is a durable control device installed in the blower tube and does not require individual control.

The Laval shaped restrictor is a nozzle having an asymmetric hourglass shape having a converging nozzle inlet and a branching nozzle outlet, which accelerates the heat gas introduced into the nozzle inlet and reaches a sonic speed at the nozzle neck. It is carefully balanced to reach supersonic speed at the nozzle outlet.

Over the Laval type restriction, the pressure drop increases to the square of the mass flow until it reaches the speed of sound (choked condition). At more mass flows, the pressure drop increases sharply.

In order to provide kinetic energy with a flow similar to that of kinetic energy in a normal configuration, the diameter of the tuyere outlet must be in the same size range as the velocity must be maintained in the same range. Of course, the flow rate through the blower tube is no longer affected by what occurs in the front of the tuyere. The flow state of the balanced Laval nozzle depends only on the pressure conditions upstream of the Laval nozzle.

The flow of hot gas into the furnace is only controlled by changing the pressure conditions of the blowers.

The Laval shaped restriction further makes it possible to reacquire a portion of the pressure, and in some cases, the total energy consumption of the blower can be reduced compared to a typical blower tube arrangement with smaller vents arranged to achieve uniform distribution. have.

Preferably, at least a portion of the Laval shaped restriction can be operated in an ultrasonic manner. Of course, when at least a portion of the Laval shaped restriction is operated ultrasonically, the redistribution of the flow through the different blower tubes is improved. For those vents that may have a higher mass flow without the Laval-type restriction, the mass flow is choked to the Laval-type restriction and therefore redistributed to other vents. Thus a more uniform flow through the vents is achieved.

Most preferably, all of the Laval shaped restrictors are operated in an ultrasonic manner. If all the tuyeres are choked by the laval-shaped restriction, the flow at each tuyere is the same.

The method advantageously consists in controlling the mass flow of hot gas through the blower pipe by a blower arranged upstream of the bustle pipe.

According to an embodiment of the present invention, the laval type restricting portion may be disposed in the down leg portion. Preferably, however, the laval type restriction is arranged in the blower pipe.

According to one embodiment, the laval restriction is arranged at the rear end of the blowing pipe, near the elbow portion. According to a further embodiment, the laval restricting portion is arranged at the front end of the blowing pipe, near the connecting portion of the opening arranged in the furnace shell.

The tuyere may be disposed in an opening disposed in the shell of the furnace, and the blow pipe is connected to the tuyere to blow hot gas into the furnace through the tuyere.

Alternatively, by introducing a Laval type restriction into the blower tube, a diffuser is arranged in the opening disposed in the shell of the furnace, and the blower pipe is connected to the diffuser to blow hot gas into the furnace through the air vents.

Preferably, the diffuser is formed and arranged for extension of the outlet of the laval shaped restriction. In addition, the blow pipe is preferably at the downstream side of the laval shaped restrictor gradually increasing its inner diameter to form an extension from the outlet of the laval shaped restrictor.

1 shows a blower tube arrangement for supplying hot gas, which is generally hot air, through a furnace shell 12. The blower tube arrangement includes a tuyeres 14 arranged in the furnace shell 12. The tuyere 14 is maintained in position by a tuyere cooler 16. Further, the blower tube arrangement is composed of a blower tube 18 for injecting heat gas from the bustle main (not shown) to the tuyere 14.

The tuyere 14 has a blower body 20 having a front face 24 and an opposite rear face 26. The blowing channel 28 is disposed centrally through the blowing body 20 and extends from the rear surface 26 to the front surface 24. The rear face 26 of the tuyere 14 is configured to be connected to the front portion 32 of the blow pipe 34, which is generally downleg in the form of an elbow portion 37 at the rear portion 36 on the opposite side. Part 39 is then connected by bustle pipes 38 (not shown). The blow pipe 34, the elbow portion 37, and the down leg portion 39 are generally referred to collectively as the blower pipe 18.

Furthermore, auxiliary fuel injection lances (not shown) may be provided at the blower pipes for supplying auxiliary fuels, typically pulverized coal or natural gas, from the tuyere into the furnace. Due to the fuel injection into the furnace, the volume of coke injected into the furnace can be reduced. Fuels such as coal, for example, are generally cheaper than coke, which can reduce the operating costs of the furnace. Typically, this auxiliary fuel is injected into the hot gas stream in the tuyere 14 or blower pipe 34. Further, gas blowing lances (not shown) may be provided to inject oxidizing gas, such as oxygen, into the fuel to enhance combustion of the auxiliary fuel. Combined lances may be used to inject auxiliary fuel and oxidizing gas into the tuyeres 14 or blower pipe 34. These combine lances, commonly referred to as oxycoal lances, use two concentric pipes that separate auxiliary fuel and oxidizing gas and feed them to the tip of the combine lance.

According to one important aspect of the present invention, the Laval type restricting portions 40, 40 ′, 40 ″ are disposed in the blower tube 18.

 1 shows one embodiment of the present invention, where a Laval shaped restriction 40 is disposed in the down leg portion 39 of the blower tube 18. The Laval shaped limiter 40 has an asymmetric hourglass shape with converging nozzle inlet 42, nozzle neck 44, and branching nozzle outlet 46, as shown more clearly in FIG. 2. It is a nozzle having. The nozzle is precisely balanced to accelerate the heat gas entering the nozzle inlet 42, to reach the speed of sound at the nozzle neck 44, and to reach supersonic speed at the nozzle outlet 46.

By placing the Laval restrictor 40 in the downleg portion 39 of the ventilator 18, the part of the ventilator 18 downstream of the laval restrictor 40 is generally used today. It may have a flow channel with a larger diameter than those. However, the front diameter of the tuyere does not need to vary. A pressure drop for uniform distribution occurs in the Laval type restricting portion 40, and the flow rate of the hot gas through the blower pipe 18 is affected by the state of the downstream side of the Laval type restricting portion 40. Do not receive.

3 shows another embodiment according to the present invention having a different configuration for the Laval-type restriction 40 '. Most of the features of the above embodiment are the same as the embodiment shown in Fig. 1, and thus will not be described in more detail below. Like reference numerals refer to like features.

In this embodiment, the Laval type restricting portion 40 ′ is arranged at the rear portion 36 of the blow pipe 34, near the elbow portion 37. The laval restraint 40 'itself is very similar to the laval restraint 40 of FIG. However, the branching nozzle outlet 46 ′ is constructed and arranged to branch in such a way as to create a continuous branching channel reaching the furnace. The blow pipe 34 has a central channel 48 formed therein to fit the continuous branch channel. The front part 32 of the blow pipe 34 is in contact with the rear face of the diffuser 50 disposed in the furnace shell 12. This diffuser 50 has a central channel 52 adapted to the continuous branch channel. This arrangement has the advantage of further reducing the pressure loss in the hot gas distribution system.

Figure 4 shows another embodiment according to the present invention having another configuration for the Laval-shaped restriction 40 ". Most of the features of this embodiment are the same as the embodiment shown in Figure 3, and therefore The same reference numerals refer to the same features.

In the present embodiment, the Laval shaped limiting portion 40 "is disposed in the vicinity of the portion connected to the opening 32 disposed in the shell 12 of the blast furnace in the front portion 32 of the blow pipe 34. The laval shaped restriction The portion 40 "itself is also very similar to the Laval type restriction 40 of FIG. 1 or FIG. However, the branching nozzle outlet 46 ″ is constructed and arranged to branch in such a way as to create a continuous branch channel reaching the furnace. The blower pipe 34 is a central channel formed to fit the continuous branch channel. The interior of the blower pipe 34 is in contact with the rear of the diffuser 50 disposed in the furnace shell 12. The diffuser 50 is connected to the continuous branch channel. It has a central channel 52 formed to be suitable.

5 shows a heat gas distribution system 54 for supplying heat gas to the furnace. The heat gas distribution system 54 consists of a bustle pipe 56 around the outer circumference, which surrounds the outer cylinder of the furnace and is arranged at regular intervals therefrom. The bustle pipe 56 receives the hot gas from the gas main 58 and redistributes it around the furnace. Thereafter, the heat gas is injected into the furnace through the plurality of blower pipes 18 from the bustle pipe 56. In this figure, it appears that the blower tube 18 adjacent to the gas main 58 tends to receive more heat gas than the blower tube 18 located further away from the gas main 58.

Example

To illustrate the effectiveness of the proposed method, a pressure loss model was used once in a system with and without a Laval restrictor to show the difference between the mass flows through individual vents. From the results shown in FIG. 6, it can be seen that the mass flow is significantly more uniform when the Laval type restriction is used. The standard deviation in the system without Laval type restriction was 0.304, while the standard deviation in the system with Laval type restriction was 0.086, which was significantly lower. Thus, the Laval type restriction makes it possible to achieve a significantly more uniform hot gas distribution in the furnace.

Finally, the length and position of the laval-type restriction portion shown in the drawings are not limited thereto, and the length and position of the laval-type restriction portion in the blower pipe may vary.

12: furnace shell
14: tuyere
16: tuyere cooler
18: tuyere stock
20: tuyere body
24: front face
26: rear face
28: tuyere channel
32: front portion
34: blowpipe
36: rear portion
37: elbow
39: downleg section
40: Laval type restriction
42: nozzle entry section
44: nozzle throat
46: nozzle exit section
48: central channel
50: diffuser
52: central channel
54: hot gas distribution system
56: bustle pipe
58: gas main

Claims (12)

In a method of injecting heat gas into a shaft furnace, in particular in a blast furnace:
Providing a blower pipe arrangement comprising a bustle pipe arranged to receive heat gas at a gas main, and a plurality of tuyerre stocks for injecting heat gas from the bustle pipe to the furnace. Wherein the blower pipe is disposed around the outer circumferential surface of the furnace, and each of the blower pipes has a downleg section for connecting to the bustle pipe, and the blower pipe is disposed in the furnace shell opening. A blow pipe for injecting hot gas, and an elbow disposed between the down leg portion and the blow pipe,
The method comprises:
A method for injecting hot gas into the furnace, characterized in that it further comprises providing a Laval type restriction in each of the blower pipe.
The method of claim 1,
Operating at least a portion of said laval type restricting portion in an ultrasonic manner.
3. The method according to claim 1 or 2,
And operating all of the laval type restriction portions in an ultrasonic manner.
4. The method according to any one of claims 1 to 3,
Controlling a mass flow of hot gas through the blower pipe by a blower disposed upstream of the bustle pipe.
5. The method according to any one of claims 1 to 4,
And disposing the laval type restricting portion in the downleg portion of the blower pipe.
5. The method according to any one of claims 1 to 4,
And arranging the Laval type restricting portion disposed in the blowing pipe of the blowing pipe.
The method according to claim 6,
And arranging the laval type restricting portion at the rear end of the blowing pipe in the vicinity of the elbow portion.
The method according to claim 6,
And arranging said laval type restricting portion at a front end of said blower pipe near a connecting portion of said opening disposed in said shell of said furnace.
The method according to any one of claims 1 to 8,
And providing a tuyere in the opening disposed in the shell of the furnace, wherein the blow pipe is connected to the tuyere to blow hot gas into the furnace through the tuyere. Method for infusion.
9. The method according to any one of claims 1 to 8,
Providing a diffuser in the opening disposed in the shell of the furnace, wherein the blow pipe is connected to the diffuser to blow heat gas into the furnace through the tuyeres. Method for infusion.
11. The method of claim 10,
Providing a diffuser formed and arranged to be an extension of the outlet of the laval shaped restrictor.
11. The method of claim 10,
Providing a blower pipe on the downstream side of the laval shaped restrictor, the blower pipe having an inner diameter gradually increasing to form an extension exiting the outlet of the laval shaped restrictor. .

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