JPS6024309A - Method for supplying continuously hot air to metallurgical furnace - Google Patents

Abstract

PURPOSE:To provide a titled device which permits smooth and easy startup, stationary and preheating operations by providing bleeder pipes for venting gas to a hot air pipe before and behind a hot air valve and providing a by-pass pipe for waste combustion gas to a recuperator. CONSTITUTION:A continuous hot air feeder subjects cold air to a heat exchange with waste combustion gas in a recuperator 30 and supplied to hot air to a metallurgical furnace 1. Bleeder pipes 52, 53 for venting gas are provided before and behing a hot air valve 33 to a hot air feeder 3 of such device. A by-pass pipe 56 provideg with an atm. air suction pipe 59 and a blower 58 is provided between waste combustion gas pipe 35 and 36 on inlet and outlet sides in which the waste combustion gas generated in a combustion gas 34 is passed to said recuperator 30. The discharge of the hot air from the pipe 3 and the temp. control of the waste combustion gas on the inlet and outlet sides of the recuperator are thus made easy and the smooth and easy start-up, stationary and preheating operations of the hot air feeder are made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hot air supply device that continuously supplies high temperature hot air to a metallurgical furnace such as a blast furnace.

Generally, as a method for supplying hot air to a metallurgical furnace, mainly a blast furnace, a hot blast furnace method as shown in FIG. 1 is used. FIG. 1 shows an example in which eight hot air stoves are provided, and the operating modes of one-burning-two-air blowing and two-burning-one-air blowing are alternately repeated.

In the figure, 1 is a blast furnace, and 2a, 2b, and 2C are hot blast furnaces, and as described later, hot air is blown from any one or two of these hot blast furnaces through a hot air supply pipe 8 through an annular pipe 4. On the inlet side of the hot air stove, a blower 5 is connected to supply cold air through a cold air pipe 6 for the air blowing operation mode, and a steam supply pipe 7 and an oxygen gas supply pipe 8 are connected to the cold air pipe 6, respectively. Flow control valves 9 and 10
Also, for the combustion mode of operation, an air supply pipe 11 and a fuel gas supply pipe 12 are connected to supply air and fuel gas via heat exchangers 18 and 14, respectively, and an air fan is connected to the air supply pipe 11. Further, a flue 16 for discharging combustion exhaust gas is connected to a chimney 18 via a heat exchanger 17 on the outlet side of the hot air stove.

In the conventional hot air supply device using the hot air stove system configured as described above, for example, while the hot air stove 2a is blowing air, the hot air stoves 2b, 2
If c is in combustion, in the hot air stove 2a that is blowing air, the cold air valve 19a and the hot air valve 20a are open, and the air valve 21a is open.
, the gas valve 22a, the flue valves 28a, and g4a are in the closed state,
Cold air blown by the blower enters the hot blast furnace 2a through a cold air pipe, is heated inside the hot blast furnace 2a, becomes hot air, and is blown to the blast furnace 1 through a hot air supply pipe 8. In addition, since the amount of heat stored in the hot air stove 2a during air blowing changes T with time, the air blowing temperature also changes T. By adjusting 26, the temperature of the hot air supplied to the blast furnace 1 is controlled to be constant by mixing cold air into the hot air. On the other hand,
In the hot air stoves 2b, 2c during combustion, the cold air valves 19b, 190° hot air valves 20b, 200 are closed, and the flue valves 28b, 230 are closed.

z4b, 24c are open, air valves 21b, 21c, gas valve 2
2b and 22C are in the open state, combustion air and gas are combusted in the hot air stove burner, the bricks in the hot air stove are heated, and the combustion exhaust gas is discharged into the atmosphere through the flue 16 and the chimney 18.

As mentioned above, conventional hot air supply systems using hot air stoves require multiple furnaces to repeatedly blow air and heat by combustion, and require complex equipment such as various valves and switching control devices to switch between them. Not only that, but also changes in the blowing temperature and blowing pressure inevitably occur, which poses problems in blast furnace operation.Therefore, in order to solve the above-mentioned problems, it was necessary to continuously supply hot air. A hot air supply device configured to supply hot air has recently been proposed in Japanese Unexamined Patent Publication No. 54-153705. As shown in FIG. 2, this device uses a ceramic recuperator 30 as a heat exchanger, and cold air is supplied to the recuperator 30 through a control valve 31 and an open valve 32 through a pipe 6. The combustion exhaust gas pipe 85 is connected to the inlet side combustion exhaust gas pipe 85 from the combustion exhaust gas portion 84 to exchange heat with the cold air flowing through the cold air pipe 6.
The exhaust gas after heat exchange is supplied to the recuperator 80 through the outlet side combustion exhaust gas pipe δ6 to the exhaust turbine 40 for driving the drive shaft 89 of the air fan 87 and the fuel gas fan 88 as a power source. There is. 41
indicates an auxiliary motor connected to the drive shaft 89. With this configuration, combustion air and fuel gas are supplied to the pressurizing air 7 and fuel gas fans, respectively, so that the heating side gas pressure becomes the same pressure as the heated side gas pressure in the recuperator 80. 88 to control the gas pressure so that the pressure difference between the two becomes zero in the recuperator 8o, and also drive the exhaust gas turbine 40 by the IE force and thermal energy possessed by the combustion exhaust gas discharged from the recuperator 80. Au is used as a driving source for the boosting fans 8'l and 8B described in 1u above. Reference numerals 42 and 48 are pressure detectors, 44 is a pressure regulator, and 45 is a combustion exhaust gas pipe 46 of the exhaust turbine 40. This is a control valve installed in the

However, the hot air supply system using a recuperator configured as described above requires pressure control to maintain combustion air and fuel gas at high pressure, which increases equipment costs and requires shutting down of metallurgical furnaces such as blast furnaces. Because of the complex and difficult control that occurs when restarting a blast furnace or restarting steady operation after a shutdown, a device that uses a recuperator to continuously supply hot air to a blast furnace has not yet been put into practical use. The reality is that there is not.

The present invention solves the above-mentioned problems and provides a continuous hot air supply device suitable for smooth operation of a metallurgical furnace such as a blast furnace using a recuperator. purpose.

The invention will now be explained with reference to the drawings.

Part 3 shows a first example of a continuous hot air supply device according to the present invention, and in the drawings, parts similar to those of the conventional device described above are denoted by the same reference numerals as described above.

Metal or ceramic recuperator 8 as shown
A hot air supply device 8 for supplying hot air to a metallurgical furnace l such as a blast furnace and a cold air pipe 6 for supplying cold air from a blower 5 via a flow rate control valve 50 are connected to one of the outlet and inlet sides of the 0, respectively. Inlet side and outlet side combustion exhaust gas pipes 85, 88 through which combustion exhaust gas from the combustion chamber 84 flows are connected to the other inlet side and outlet side, respectively, and two heat exchanges are performed between the combustion exhaust gas and cold air within the recuperator 30, It is configured to continuously supply high temperature hot air to the metallurgical furnace l.

The hot air supply pipe 3 is equipped with a cold air pipe 6 and a hot air supply pipe s before and after the hot air valve 38 in order to enable gradual shutdown of the metallurgical furnace 1 or start-up operation after the shutdown. A bleeder pipe 52 for dissipating air and a bleeder pipe 58 for dissipating residual hot air around the annular pipe 4 are provided, and bleeder valves 54 and 55i are attached to these bleeder pipes 52 and 53.

In addition, a temperature adjustment bypass pipe 56 is connected between the inlet side and outlet side combustion exhaust gas pipes 35686 via an on-off valve 57, and a blower 58 and an atmospheric suction pipe 59 are connected to the bypass pipe 56.
A temperature detector 6o is provided in the combustion exhaust gas pipe δ5 on the inlet side of the recuperator, and a regulating valve 62 and an atmospheric air introduction regulating valve are operated via a valve opening/closing operator 61 in response to a temperature signal detected by the temperature detector 60. Flow M by 63
The combustion exhaust gas and the atmosphere exiting the recuperator are fed into the combustion exhaust gas pipe 85 on the inlet side of the recuperator to adjust the temperature.

Furthermore, the temperature of the air blown to the metallurgical furnace 1 is determined by controlling the combustion air flow rate adjustment valve 66 and the fuel gas flow rate adjustment valve 67 via the valve opening/closing operator 65 based on the temperature detector 64 provided in the hot air supply pipe 3. This is done by adjusting the flow rates of combustion air and fuel gas to the fuel mold 84.

Next, regarding the first embodiment shown in FIG. 3, we will explain the overall operation of the metallurgical furnace 1 from start-up to steady operation. At the same time, the hot air valve 83 is opened, and the cold air is supplied to the metallurgical furnace 1 through the first annular pipe 4.
Blow air to. Further, the opening degree of the flow control valves 9, 10, and 50 is adjusted so that the moisture content, the 0□ amount, and the air flow amount become predetermined values.

On the other hand, after the cold air has passed through the recuperator 80, the combustion air fan 15 is started, and the combustion air is introduced into the combustion chamber δ4 through the pipe 11, and the fuel gas is introduced into the combustion chamber δ4 through the pipe 12. After being combusted in the bed 34, it flows through the flue gas pipe 85 to the recuperator 30. ~At the same time, open the valves 62 and 57 and start the blower 58.

The valves 66, 67 gradually open until a predetermined amount of combustion heat is reached.

Further, the opening degree of the valve 62 is adjusted so that the combustion exhaust gas temperature on the inlet side of the recuperator 80 becomes a predetermined value.
When the pressure does not drop to a predetermined value even when the pressure is fully opened, the valve 68 can be opened to introduce atmospheric air through the atmospheric suction pipe 59. Note that although the air volume is controlled by the regulating valve 62, the
It is also possible to directly control the wind foot at 58. Unnecessary combustion exhaust gas is discharged into the atmosphere from the chimney 18, but its sensible heat is recovered by the heat exchanger 17 and transferred to the heat exchangers 13 and 1 provided in the air supply pipe 11 and the fuel gas supply pipe 12.
4 is effectively used to preheat the combustion air and fuel gas.

After the above operations are continued until the predetermined temperature and air flow rate are obtained, steady operation begins. The six valves are controlled so that the side combustion exhaust gas temperature is 0. The above-mentioned air blowing control can be performed, for example, as shown in the control flow diagram of FIG. is determined by the production volume of the metallurgical furnace, and the air flow rate is controlled by detecting the flow rate in the cold air pipe 6.
This is done by adjusting the 1M control valve 50. In addition, the air blowing temperature T
Control B is based on the combustion exhaust gas temperature TR on the recuperator inlet side.
This is done by adjusting the amount of fuel gas using the valve 67 under certain conditions. As a method for keeping the temperature of the combustion exhaust gas on the recuperator inlet side constant, the temperature of the combustion exhaust gas on the recuperator inlet side is detected by the temperature detector 60,
By controlling the valve 62 or 68 via the valve opening/closing device 61, the combustion exhaust gas temperature at the recuperator inlet side is kept constant. The amount of fuel gas is adjusted in accordance with the following formula so that the temperature of the blast air reaches a predetermined value.

In addition, in Fig. 5, ΔVa is the increase or decrease of combustion air.
1. ΔVOFli' indicates the increase/decrease in combustion exhaust gas T.

ΔVg-K ('['B -, 'I'B□) In the above formula, Δv5: Fuel gas increase/decrease K: Pulse number TB: Actual measurement value of air blowing temperature T: Target value O of If the air ratio is increased or decreased, the specified air ratio (
1.0~1.20), the amount of combustion air is also Jj
~It is better to reduce it. The above makes it possible to generate stable hot air.

Next, to explain the operating method when stopping the metallurgical furnace 1 from steady operation, first, the fuel gas adjustment valve 67 is closed, and then the air valve 66 is closed to stop combustion. Next, the blower 58 is stopped and the valve 6257 is closed. Then valve 9. Close the lO, gradually throttle the valve 50 to reduce the pressure, open the bleeder valve 54 to let the blowing air in the cold air pipe 6 and the hot air supply pipe 8 graze in the atmosphere, and at the same time close the hot air valve 51.
The bleeder valve 55 is opened to dissipate the hot air between the annular pipe 4 and the hot air valve 83 into the atmosphere, and the blower 5 is stopped, thereby entering a hibernation state.

When entering such a shutdown state, it is necessary to preheat the recuperator so that the metallurgical furnace can start operating at any time. Preheating of the recuperator 30 when it is inactive depends on the operating level, but when high production is to be achieved, the preheating of the recuperator 30 is
Is it time for F to start up? r: Necessary for short rice production. The reason for this is that if the recuperator is not preheated while it is at rest, it will radiate heat and the amount of heat storage will decrease, so most of the combustion heat at startup will be used to preheat the recuperator itself, and the temperature of the cold air will rise. This is because it takes Therefore, the recuperator? In order to preheat, it is preferable to start combustion at a combustion amount of 84 approximately 80 minutes before starting up the metallurgical furnace.

In the example shown in FIG. 3, the amount of combustion for preheating and the amount of cold air are both smaller than in normal operation, but the system is operated in substantially the same manner as normal operation. The recuperator 30 is preheated while the preheated air that has passed through the recuperator 30 is dissipated through the bleeder valve 54. At this time, the hot air valve δ8 is kept closed to prevent it from entering the metallurgical furnace 1.

As described above, in the configuration shown in FIG. 3, the amount of air heated by the recuperator is dissipated from the feeder tube 52 during preheating, so there is a drawback that energy loss is large. In order to prevent such energy loss during preheating, it is preferable to send the hot air flowing through the hot air supply pipe 8 to various heat exchangers by an appropriate method during preheating. As shown in the figure.

In the example shown in FIG. 4, a valve 68 is inserted between the heat exchanger 18 of the combustion air supply pipe 11 and the air flow rate adjustment valve 66, and the air supply pipe 11 The cold air pipe 6
The air supply pipe 11 is connected to the hot air pipe 8 through a pipe 71 through a valve 72 between the valves 66 and 68.

By forming the grooves in this way, when the metallurgical furnace 1 is at rest, the valves 88, 54, 9, 10, 50° 67 and 6
8 are closed and the valves 70' and 72 are opened, the combustion air fan 15 is started to flow the combustion air into the recuperator 80 through the pipe 69 and the cold air pipe 6,
Preheated air is introduced into the combustion chamber 84 via the hot air supply pipe 3, the pipe 71, and the combustion air supply pipe 11. Further, after the air fan 15 is started, the fuel gas flows into the combustion chamber 34, and then the valve 67 is opened to flow into the combustion chamber 84. As a result, the combustion gas is preheated to the recuperator No. 30, and the combustion air is The combustion gas that has also preheated the recuperator 80 is at outlet 1! II The combustion gas is discharged from the chimney 18 via the flue gas pipe 36, and at this time, the sensible heat of the combustion gas is recovered by the heat exchanger 17 and used for preheating the combustion air and fuel gas in the heat exchangers 18 and 141. . Also,
In order to control the combustion exhaust gas temperature on the recuperator inlet side to a predetermined value, the valve 62.57 is opened, the fan 58 is activated, and a part of the combustion exhaust gas flows into the outlet side combustion exhaust gas pipe 36.

The preheating method described above allows for smooth startup of operations after suspension.

Another preheating method is to use a blower instead of a combustion air fan. In this method, in the configuration shown in FIG. Recuperator 80, hot air supply pipe 8. Suga 71, through combustion air supply g11, to combustion 84
However, this method is not preferred as it is more power-intensive than the preheating method using a combustion air fan.

According to the present invention, the hot air supply pipe that supplies hot air to the metallurgical furnace through the hot air valve is provided with a degassing leader pipe before and after the hot air valve, and the exhaust gas pipes on the inlet and outlet sides of the recuperator are connected by bypass pipes. By bypass connection and providing a blower and an air collection side pipe to the bypass pipe, it is possible to smoothly and easily perform start-up operation, steady operation, and preheating operation in continuous supply of hot air to the metallurgical furnace. .

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a hot air supply device using a conventional hot air stove method, Fig. 21A is a schematic diagram of a hot air supply device using a conventional heat exchange method using a ceramic recuperator, and Fig. 8 is a schematic diagram of a hot air supply device according to the present invention. FIG. 4 is a schematic diagram showing a first example of the hot air supply device according to the present invention. FIG. 5 is a fft[I flow diagram of the hot air supply device according to the present invention. 1... Metallurgical furnace 3... Hot air supply pipe 4... Annular pipe 5... Blower 6... Cold air pipe 7... Steam supply pipe 8... Oxygen gas supply pipe 9.10...・Flow rate adjustment valve 11...Combustion air supply pipe 12...Fuel gas supply pipe 18.14.
... Heat exchanger 15 ... Air fan 17 ... Heat exchanger 18 ... Chimney 30 ... Recuperator 88 ... Hot air valve 34 ...
-Combustion chamber 35...Inlet side combustion exhaust gas pipe 86...Outlet side combustion exhaust gas pipe 5o...Flow rate adjustment valves 52, 58
... Pleader pipe 54, 55 ... Bleeder valve 56.
...Temperature adjustment bypass pipe 57...BFJ closing valve 58
...Blower 59...Air collection side pipe 60...Temperature detector 61...Valve opening/closing operation device 62.63...Adjusting valve 64...Temperature detector 65...Valve opening/closing operation Vessel 66
．． 67...Adjusting valve 68...Valve 69...Pipe 70...Valve 71...Pipe 72...Valve ρ Patent applicant Kawasaki Steel Corporation

Claims (1)

[Claims] 1 A recuperator (aO) is installed in the hot air supply piping system to the metallurgical furnace to exchange heat with combustion exhaust gas to produce high-temperature hot air, and a hot air valve (3) is installed from this recuperator to the metallurgical furnace (1).
3) A degassing leader pipe (52°58) is installed before and after the hot air valve (33) to the hot air supply pipe (δ) that supplies hot air through the hot air valve (33).
The inlet-side and outlet-side combustion exhaust gas pipes (85, 86) through which the combustion exhaust gas flows through the recuperator are bypass-connected by a bypass pipe (56), and a blower (58) and an atmospheric side pipe are connected to the bypass pipe. (59) A continuous hot air supply device for a metallurgical furnace, characterized by comprising: