JPH07113110A - Device for recovering heat in converter and control method thereof - Google Patents

Abstract

PURPOSE:To provide a heat recovery device of a converter and a control method thereof, by which the equipment cost and the operation cost can be reduced and the heat can be recovered stably and efficiently. CONSTITUTION:In the heat recovery device provided with a skirt cooling device 31 having a cooling water circulating pipe line 22 for cooling the skirt 2 covering the furnace opening part of the converter 1, a hood 3 and a radiation cooler 4 providing the cooling water pipes, a boiler drum 7 connected with the hood 3 and the radiation cooler 4, a deaerator 16 connected with the boiler drum 7, a water supplying tank connected with the skirt cooling device 31 and the deaerator 16 are provided, further, a heat exchanger 31 in which a high temp. side flowing passage is inserted into the cooling water circulating piping 22 and a low temp. side flowing passage into a pipe line 14 for connecting the water supplying device 12 and the deaerator 16, respectively, a cooling water expansion tank 24 arranged in the cooling water circulating pipe line 22 at the inlet side of the heat exchanger 31 and a flow rate adjusting device 36 arranged in a skirt temp. adjusting pipe line 35 for connecting the water supplying tank 12 with the outlet of the lower temp. side of the heat exchanger, are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat recovery device for a converter and a control method therefor, and more particularly to a device for recovering heat from a skirt directly above a furnace opening and a control method therefor.

[0002]

2. Description of the Related Art Exhaust gas generated in a converter is about 1450 ° C
The temperature is high and the CO concentration is high. Therefore, a hood or a duct is arranged at the furnace opening of the converter to collect the exhaust gas. In addition, a skirt that can be raised and lowered is placed directly above the converter,
During scouring, the skirt is lowered to reduce the distance from the converter furnace opening to suppress combustion of CO gas due to air suction at the furnace opening. Further, a hood cooler provided in the hood or a duct and a radiant cooler provided subsequent to the hood cooler generate steam by sensible heat of exhaust gas to recover exhaust heat. In addition, the skirt is also equipped with a cooler to recover a part of the exhaust heat. When the skirt is raised or lowered or the converter is tilted due to exhaust gas recovery, the metal attached to the furnace mouth of the converter contacts the skirt and damages the skirt's water pipe.
High-pressure steam may be ejected. Therefore, for heat recovery at the skirt portion, the skirt is cooled by the hot water cooler instead of the steam recovery type cooler.

As a hot water exhaust heat recovery device for a skirt, there is, for example, a converter exhaust gas cooling device disclosed in Japanese Patent Laid-Open No. 3-115517. This cooling device is equipped with an atmosphere open tank for partially evaporating the warm waste water that has cooled the skirt to the atmosphere and lowering the temperature of the cooling water by the latent heat of the self-evaporation of the warm waste water. Further, it is provided with a hot water temperature control means for controlling the temperature of the cooling water in the atmosphere open tank to a temperature near 100 ° C., and a flow rate control means for the hot water directly supplied from the atmosphere open tank to the boiler feed water deaerator. There is.

However, the above conventional cooling device requires a large-capacity device such as an atmosphere open tank for ensuring the cooling of the hot water by self-evaporation and a steam injection control device for controlling the temperature of the hot water. Equipment costs are high. In addition, in order to compensate for the evaporation of cooling water from the atmosphere open tank, the supply of regular makeup water to the skirt circulation water and the increase in the amount of chemicals used for water quality management to control the quality of makeup water are used. There is also the problem of high costs.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a heat recovery device for a converter and a control method therefor capable of reducing the facility cost and the operating cost, and recovering heat stably and efficiently. It is provided.

[0006]

A heat recovery device for a converter according to the present invention is a skirt cooling device having a cooling water circulation pipe for cooling a skirt covering a furnace opening of the converter, a hood provided with a cooling water pipe, and radiation. Heat recovery of a converter equipped with a cooler, a hood and a boiler drum connected to the cooling water pipes of the radiant cooler, a deaerator connected to the boiler drum, and a water supply tank connected to the skirt cooling device and the deaerator In the device, a high temperature side flow passage is in the cooling water circulation pipe, and a low temperature side flow passage is inserted in the pipe connecting the water supply tank and the deaerator, respectively, at the inlet side of the heat exchanger. A cooling water expansion tank provided in the cooling water circulation pipe, and a flow rate adjusting device provided in a skirt temperature adjusting pipe that connects the water supply tank and the outlet on the low temperature side of the heat exchanger are provided.

According to the heat recovery control method of the converter of the present invention, the flow rate of the skirt temperature adjusting pipe is adjusted based on the deaerator feed water amount in the heat recovery apparatus to obtain the low temperature side flow rate of the heat exchanger. Hold the flow rate at the skirt temperature.

In the converter heat recovery control method of the present invention, in the heat recovery device, Qb (deaerator feed water flow rate) <Qhe
When the flow rate on the low temperature side of the heat exchanger is the required skirt temperature, the flow rate on the low temperature side of the heat exchanger is Qb (deaerator feed water flow rate) + Qes (skirt temperature control pipe flow rate), and Q
After the time of b> Qhe, Qes = 0.

In still another heat recovery control method for a converter according to the present invention, in the heat recovery device, the skirt temperature adjusting conduit is narrowed to a predetermined opening, and the flow rate of the narrowed skirt temperature adjusting conduit is set to Qeso. At this time, the heat exchanger low temperature side flow rate is controlled as Qeso + Qb regardless of the deaerator feed water flow rate Qb.

[0010]

The cooling water in the skirt circulates in the cooling water circulation line through the hot side of the heat exchanger. The expansion of the cooling water heated by the skirt is absorbed by the cooling water expansion tank. Also,
The cooling water is a heat exchanger and is cooled by pure water flowing on the low temperature side thereof. On the contrary, the cooling water of the skirt heats the pure water sent to the deaerator through the low temperature side of the heat exchanger, and a part of the exhaust heat is recovered.

The flow rate of the pure water flowing through the low temperature side of the heat exchanger is set so that the cooling water has a required temperature, for example, a temperature not exceeding the saturation temperature. When the amount of pure water sent to the deaerator (deaerator water supply amount) changes, adjust the flow rate of the skirt temperature adjustment pipe line according to the deaerator water supply amount, and set the heat exchanger low-temperature side flow rate to the required flow rate. Hold on. For example, when the water supply amount of the deaerator is increased, the flow rate of the skirt temperature adjusting pipeline is reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a heat recovery device for a converter according to the present invention and is a schematic view of the entire device. A skirt 2 that can move up and down is arranged directly above the furnace opening of the converter 1. A hood 3 and a radiation cooler 4 extend upward from the skirt 2. A cooling water pipe group (not shown) is formed in the hood 3 and the radiation cooler 4. The cooling water pipe group is the circulation pipe 6
It is connected to the boiler drum 7 via. Further, a boiler circulation pump 8 is attached between the inlet side of the cooling water pipe group and the boiler drum 7. Cooling water is supplied from the boiler drum 7 to the cooling water pipe group, and the cooling water is heated by the exhaust gas passing through the hood 3 and the radiation cooler 4.

A water supply main 14 connected to a water supply tank 12.
The deaerator water supply pump 13 is connected to the water supply mains 1
An expansion tank water supply pipe line 15 branches from 4. Pure water from the water supply tank 12 is supplied to the deaerator 16 via the water supply main pipe 14. The pure water deaerated by the deaerator 16 is supplied to the boiler drum 7 by the boiler feed water pump 18.

The skirt 2 is provided with a skirt cooling device 21. The skirt cooling device 21 is provided with a cooling water circulation pipe line 22, a skirt circulation pump 23 is provided on the skirt entrance side of the cooling water circulation pipe line 22, and a cooling water expansion tank 24 is provided on the exit side. The cooling water flow meter 25 and the cooling water thermometer 26 monitor the flow rate and temperature of the cooling water flowing through the cooling water circulation conduit 22. If the cooling water thermometer 26 detects an abnormal temperature, a converter blowing emergency stop signal is issued. When the circulating cooling water in the cooling water circulation conduit 22 is discharged to the outside due to the repair of the skirt 2 or the like, the expansion tank make-up water valve 29 is opened by the signal from the water level gauge 27 of the cooling water expansion tank 24 to open the cooling water expansion tank. Add cooling water to 24.

The skirt cooling device 21 further includes a heat exchanger 31. The high temperature side passage 32 of the heat exchanger 31 is
It is inserted in the cooling water circulation line 22 between the cooling water expansion tank 24 and the skirt circulation pump 23. The low temperature side flow passage 33 of the heat exchanger 31 is inserted into the water supply main pipe 14 at the inlet side of the deaerator 16.

The water supply tank 12 and the outlet side of the heat exchanger 31 are connected by a skirt temperature adjusting pipe 35, and a skirt temperature adjusting valve 36 is attached to the skirt temperature adjusting pipe 35. The signals from the flowmeter 37 of the water supply main 14 and the flowmeter 38 of the skirt temperature adjusting conduit 35 are input to the skirt temperature controller 39, and the skirt temperature adjusting valve 3
6 is opened and closed by an operation signal from the controller 39.

In the heat recovery device constructed as described above, the steam generated in the hood 3 and the radiation cooler 4 is supplied to the boiler drum 7 through the circulation pipe 6. The steam of the boiler drum 7 is supplied to a required steam consuming facility via the boiler drum pressure control valve 9. Boiler drum water gauge 41
And the signal from the steam flow meter 42 is input to the boiler water level controller 44. A signal from the feed water flow meter 43 on the outlet side of the boiler feed pump 18 is also input to the boiler water level controller 44. The boiler feed water flow rate control valve 45 is opened and closed based on an operation signal from the boiler water level controller 44, and pure water is sent from the deaerator 16 to the boiler drum 7 by the boiler feed water pump 18.

The water supplied to the deaerator 16 is controlled by the deaerator water level gauge 46.
The deaerator water level control valve 47 is opened / closed based on the signal from to supply pure water from the water supply tank 12 to the deaerator 16. At this time, when the pure water from the water supply tank 12 passes through the heat exchanger 31, it is heated by the skirt circulation water, heated, and supplied to the deaerator 16.

The skirt circulation cooling water of the skirt cooling device 21 is cooled by the pure water supplied to the deaerator 16 in the heat exchanger 31 via the cooling water expansion tank 26, and then the skirt circulation pump 24 skirts it. Recycled to 2. The volume expansion of the skirt circulation cooling water due to the temperature rise due to heating in the skirt 2 is absorbed by the cooling water expansion tank 26. It also prevents the temperature of the cooling water at the skirt outlet from exceeding the saturation temperature. That is, the skirt temperature control valve 36 controls the deaerator feed water flow rate Q passing through the low temperature side flow passage 33 of the heat exchanger 31 in order to cool the skirt circulation cooling water temperature to a specified temperature or lower (less than the saturation temperature). .

FIG. 2 shows another embodiment of the present invention. In this embodiment, in the skirt temperature adjusting conduit 35 on the low temperature side of the heat exchanger 31, the orifice 51 is used as a flow rate adjusting means instead of the flow rate adjusting valve. The pressure on the outlet side of the heat exchanger 31 changes according to the change in the water supply amount of the deaerator, and thus the differential pressure across the orifice 51 also changes.
As a result, the flow rate of the skirt temperature adjustment conduit 35 changes,
The flow rate of the heat exchanger low temperature side flow path 33 is maintained at a substantially required flow rate, that is, a flow rate that maintains the skirt cooling water at a required temperature.

Here, the heat recovery control method will be described more specifically with reference to FIG. In FIG. 3, each symbol represents the next state and quantity. (A) Steady state of converter Boiler drum pressure before start of blowing is about 60% or more of drum control pressure (B) Unsteady state Boiler drum pressure before start of blowing is about 30% or less of drum control pressure ( C) Unsteady state Boiler drum pressure before the start of blowing is about 30% or less of the drum control pressure (1) Boiler drum pressure (2) Steam generation flow rate from boiler drum (3) Boiler feed water flow rate (solid line), degassing Air supply water flow rate (dotted line) (4) Cooling system flow rate of skirt cooling water (5) Total flow rate of heat exchanger (6) Skirt outlet temperature of skirt circulating water

FIG. 3 (A) shows the relationship between the outlet temperature of the skirt circulating water heat exchanger 31 in the steady state of the converter 1 and the flow rate of water supplied to the deaerator 16. When the converter 1 is continuously operating, the pressure of the boiler drum 7 ((1) in FIG. 3) is
After the start of blowing (a), steam is generated almost at the same time with little time delay and reaches the specified pressure (Pset). As shown in (2) of FIG. 3, the generation of steam lowers the water level of the boiler drum. Based on the boiler water supply command from the boiler drum water level gauge 41, the boiler drum water supply flow rate control valve 45 is opened, and the boiler water supply pump 18 supplies water to the boiler drum 7 as indicated by the solid line in (3) of FIG. 3. Almost at the same time, the water supply command from the deaerator water level gauge 46 also supplies water to the deaerator 16 as indicated by the dotted line (3) in FIG. 3. Therefore, the skirt circulation cooling water is also cooled through the heat exchanger 31 with no time delay, and the skirt circulation cooling water temperature does not exceed the saturation temperature of Testop as shown in (6) of FIG. 3 and is stable. Operation is continued.

However, as shown in FIG. 3 (B), the hood 3 and the radiation cooler 4 are cooled during the regular repair of the converter 1 or the operation after a long break. Therefore, the internal pressure of the boiler drum 7 (shown in (1) of FIG. 3) decreases,
It takes several minutes after the start of blowing (a) until the boiler drum 7 reaches the specified pressure (Pset) for steam generation. During this period, since steam is not generated as shown in (2) of FIG. 3 (B), the boiler drum 7 and the deaerator 16 are shown as shown by a solid line and a dotted line in (3) of FIG. 3 (B). Since no pure water is supplied to the low temperature side flow path 33 of the heat exchanger 31, the skirt circulation cooling water is not cooled. That is, after the water supply to the boiler drum 7 is started, the water level of the deaerator 16 further decreases, and a few minutes until the deaerator water supply flow rate control valve 47 is opened by the water supply start command from the deaerator water level gauge 46. (About 1
For about 0 minutes), pure water is not passed through the heat exchanger low temperature side passage 33 as indicated by the symbol Tx in (3) and (5) of FIG. 3B.

On the other hand, during this period, heat input to the skirt 2 by blowing of the converter 1 causes the temperature of the skirt circulation cooling water to rise above the saturation temperature of Testop as shown in (6) of FIG. 3 (B). Since the water pipe of the skirt 2 will be damaged by heat, the blower emergency stop of the converter 1 is required.

Therefore, in order to solve the above problem, as a method of preventing the circulating cooling water temperature from becoming higher than the saturation temperature on the skirt outlet side, the methods shown in (4) and (5) of FIG. As shown, the flow rate of the low temperature side flow path 33 of the heat exchanger 31 is set to Q
As t, the flow rate (Qb) of water supplied to the deaerator 16 and the flow rate (Qes) of the skirt temperature adjusting conduit 35 are controlled by the skirt temperature controller 39 as Qt = Qb + Qes, and the low temperature side flow path 33 of the heat exchanger 31 is designed. If the flow rate is Qhe (flow rate at which the skirt circulation cooling water temperature becomes equal to or lower than the required temperature), and Qt (= Qb) <Qhe, the skirt temperature control valve 36 is opened, and (4) in FIG. As shown, the total passage cooling flow rate (Qt = Qb + Qes) of the low temperature side flow path 33 of the heat exchanger 31 is set as the design flow rate Qhe. As a result, the skirt circulation cooling water flowing in the high temperature side passage 32 of the heat exchanger 31 is cooled by the pure water flowing in the low temperature side passage 33, and the circulating cooling water temperature on the skirt outlet side is maintained at a required temperature or lower. . The feed water flow rate Qt passing through the heat exchanger 31 is
With the progress of the blowing of the converter, steam is generated from the boiler drum 7 (shown in (2) of (B) of FIG. 3), and the boiler feed water pump 18 outputs the deaerator 16 from the deaerator 16 according to a command from the boiler drum level gauge 41. Water supply to the boiler is started as shown by a solid line and a dotted line in (3) of FIG. Therefore, the flow rate Qb
Since the ratio of the flow rate Qs gradually increases, if the flow rate Qt is controlled to be constant as shown in FIG. 3C, the flow rate Qes of the skirt temperature control passage will reach the specified flow rate (Qhe). Since Qb> Qhe for the above reason, the skirt temperature control valve 36 is gradually closed to cool the skirt circulation cooling water. As a result, the temperature of the circulating cooling water at the skirt outlet is stably controlled to be equal to or lower than the saturation temperature, and the skirt 2
It is possible to prevent the water pipe from being damaged and prevent the occurrence of an emergency shutdown of the converter.

In the above control, Qt (= Qb + Q
es) = Qhe, a continuous control method in which the flow rate of the heat exchanger low temperature side flow path 33 is always a constant value, and the flow rate Qes of the skirt temperature adjustment conduit is a constant value, and when Qb> Qhe is satisfied, the flow rate is There is an ON / OFF control method that makes Qes zero. However, the efficiency of heat recovery from the circulating cooling water on the skirt exit side is almost the same as it is recovered as hot water in the water supply tank 12, and therefore may be controlled by any method.

It is also possible to employ a method in which the skirt temperature control valve 36 is used as a fixed orifice 51 to constantly pass a specified amount of cooling water to prevent the skirt circulation cooling water temperature from rising. In this case, the deaerator pump 1
3 is normally operated continuously, and cooling water is supplied to the orifice 51.
To the water supply tank 12 at a constant flow rate.

Table 1 shows specific examples.

[Table 1]

[0029]

By having the skirt cooling temperature control valve system, the skirt drainage temperature can be stably controlled to be equal to or lower than the saturation temperature, and the waste heat can be recovered from the skirt drain hot water. By preheating the boiler feed water by using the above, the amount of steam used for preheating the boiler feed water (deaerator makeup water) can be reduced, and the sensible heat of the exhaust gas can be effectively recovered and has the following effects. .

The skirt outlet temperature can be stably controlled to be equal to or lower than the saturation temperature regardless of the state of the boiler. Since the skirt outlet temperature is controlled to be equal to or lower than the saturation temperature, the atmospheric evaporation of the circulating water is suppressed and the makeup water can be reduced. The capacity of the expansion tank (1 to 1.5 m ³ ) that only considers the temperature rise of the skirt circulation system-owned water is sufficient, so the tank capacity can be reduced, and the facility cost is extremely low.

[Brief description of drawings]

FIG. 1 is a device configuration diagram showing an example of a heat recovery device of the present invention.

FIG. 2 is a device configuration diagram showing another example of the heat recovery device of the present invention.

FIG. 3 is a diagram showing an operating state of the heat recovery device shown in FIG.

[Explanation of symbols]

1 Converter 2 Skirt 3 Hood 4 Radiant Cooler 7 Boiler Drum 8 Boiler Circulation Pump 12 Water Supply Tank 13 Deaerator Water Supply Pump 14 Water Supply Main 16 Deaerator 18 Boiler Water Supply Pump 21 Skirt Cooling Device 22 Skirt Cooling Water Circulation Pipeline 23 Skirt circulation pump 24 Cooling water expansion tank 25 Circulating cooling water flow meter 26 Circulating cooling water thermometer 27 Cooling water expansion tank water level gauge 31 Heat exchanger 35 Skirt temperature control pipe 36 Skirt temperature control valve 39 Skirt temperature controller 41 Boiler drum water level 42 Steam flow meter 43 Feed water flow meter 44 Boiler drum water level controller 45 Boiler feed water flow rate control valve 46 Deaerator water level gauge 47 Deaerator feed water flow rate control valve 51 Orifice Pset Boiler drum control pressure set value Qes Skirt cooling of cooling water Flow rate of system Qhe Total flow rate through Testop skirt drainage temperature high during converter blowing emergency stop temperature setpoint a converter blowing start signal b converter blowing end signal Tx skirt uncooled time zone of the circulating water in the exchanger

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[Procedure amendment]

[Submission date] December 17, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

The skirt circulation cooling water of the skirt cooling device 21 is cooled by the pure water supplied to the deaerator 16 in the heat exchanger 31 via the cooling water expansion tank 24, and then the skirt circulation pump 23 skirts it. Recycled to 2. The volume expansion of the skirt circulation cooling water due to the temperature rise due to heating in the skirt 2 is absorbed by the cooling water expansion tank 24 . It also prevents the temperature of the cooling water at the skirt outlet from exceeding the saturation temperature. That is, the skirt temperature control valve 36 controls the deaerator feed water flow rate Q passing through the low temperature side flow passage 33 of the heat exchanger 31 in order to cool the skirt circulation cooling water temperature to a specified temperature or lower (less than the saturation temperature). .

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

FIG. 3 (A) shows the relationship between the outlet temperature of the skirt circulating water heat exchanger 31 in the steady state of the converter 1 and the flow rate of water supplied to the deaerator 16. When the converter 1 is operating continuously, the pressure of the boiler drum 7 ((1 ) in (A) of FIG. 3 )
After the start of blowing (a) of the converter 1, the steam is generated almost at the same time with little time delay and reaches the specified pressure (Pset). As shown in (2) of (A) of FIG. 3, the generation of steam lowers the water level of the boiler drum. Based on the boiler water supply command from the boiler drum water level gauge 41, the boiler drum water supply flow rate control valve 45 is opened, and the boiler water supply pump 18 is used.
Water is supplied to the boiler drum 7 as indicated by the solid line in (3) of FIG. At about the same time, the water supply to the deaerator 16 by the water supply command from the deaerator water level gauge 46 is also shown in FIG.
(A) (3) as indicated by the dotted line. Therefore, the skirt circulation cooling water also has no time delay and the heat exchanger 3
1, the skirt circulation cooling water temperature is as shown in FIG.
As shown in (6) of (A), the temperature does not exceed the saturation temperature of Testop, and stable operation is continued.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

However, as shown in FIG. 3 (B), the hood 3 and the radiation cooler 4 are cooled during the regular repair of the converter 1 or the operation after a long break. Therefore, the internal pressure of the boiler drum 7 ( shown in (1) of FIG. 3 (B) ) decreases, and after the start of blowing (a), the boiler drum 7 reaches a specified pressure (Pset) for steam generation. It takes a minute. During this period, since steam is not generated as shown in (2) of FIG. 3 (B), the boiler drum 7 and the deaerator 16 are shown as shown by a solid line and a dotted line in (3) of FIG. 3 (B). Since no pure water is supplied to the low temperature side flow path 33 of the heat exchanger 31, the skirt circulation cooling water is not cooled. That is, after the water supply to the boiler drum 7 is started, the water level of the deaerator 16 further decreases, and a few minutes until the deaerator water supply flow rate control valve 47 is opened by the water supply start command from the deaerator water level gauge 46. For (for about 10 minutes), pure water is not passed through the heat exchanger low temperature side passage 33 as indicated by the symbol Tx in (3) and (5) of FIG. 3B.

Claims (4)

[Claims] 1. A skirt cooling device having a cooling water circulation pipe for cooling a skirt covering a furnace opening of a converter, a hood and a radiant cooler provided with a cooling water pipe, and a cooling water pipe of the hood and the radiant cooler. In a heat recovery device of a converter equipped with a boiler drum, a deaerator connected to the boiler drum, and a water supply tank connected to the deaerator, a high temperature side flow path is provided in the cooling water circulation pipeline, and a low temperature side flow Heat exchangers each having a passage inserted into a pipe connecting the water supply tank and the deaerator, a cooling water expansion tank provided in the cooling water circulation pipe at the inlet side of the heat exchanger, and the water supply tank. A heat recovery device for a converter, comprising a flow rate adjusting device provided in a skirt temperature adjusting pipe line which communicates with an outlet on a low temperature side of the heat exchanger. 2. The heat recovery device according to claim 1, wherein the flow rate of the skirt temperature adjusting pipe is adjusted based on the water supply amount of the deaerator, and the low temperature side flow rate of the heat exchanger reaches a required skirt temperature. A heat recovery control method for a converter characterized by maintaining the flow rate. 3. The heat recovery device according to claim 1, wherein Qb (deaerator feed water flow rate) <Qhe (required skirt temperature,
When the flow rate on the low temperature side of the heat exchanger is Qb, the flow rate on the low temperature side of the heat exchanger is Qb (deaerator feed water flow rate) + Qes (skirt temperature control pipe flow rate), and after Qb> Qhe, Qes = 0, a method for controlling heat recovery in a converter. 4. The heat recovery apparatus according to claim 1, wherein when the skirt temperature adjusting pipeline is narrowed to a predetermined opening and the flow rate of the narrowed skirt temperature adjusting pipeline is Qeso, the deaerator feed water flow rate. Regardless of Qb, heat exchanger low temperature side flow rate is Qeso +
A heat recovery control method for a converter characterized by controlling as Qb.