JPH08210780A - Continuous heating furnace for steel - Google Patents

Abstract

PURPOSE: To prevent items to be heated from being rapidly heated on the loading side and further to prevent a cracking and a bending of steel material or the like by a method wherein the flow rate of discharged gas passed through a burner is controlled in such a way that the temperature of discharged gas on the discharging side of a heat exchanging zone is set to be in the most appropriate temperature range and further a flue is provided with a control means for controlling a flow rate of discharged gas flowing in the heat exchanging zone. CONSTITUTION: A combustion air pipe 25 and a discharged gas pipe 26 are connected to a heat accumulative type burner 9. A loading side of a heated item W of a main body F of a heating furnace us provided with a heat exchanging zone 23 for performing a heat exchanging operation between time heated item W and the discharged gas flowing toward the loading side. A heat exchanging zone 23 is connected to a chimney 28 by a flue 27. The flue 27 is provided with a furnace pressure adjusting damper 29 and a thermocouple 30 for measuring a temperature of the discharged gas. The thermocouple 30 is connected to a temperature indicating adjustor meter 31. The temperature indicating adjuster meter 31 is connected to a flow rate adjusting valve 32 arranged in a discharged gas pipe 26, and the discharged gas is discharged out of a discharging cylinder 35 by a discharged gas fan 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous heating furnace for steel using a regenerative burner.

[0002]

2. Description of the Related Art A continuous heating furnace for steel using a regenerative burner is disclosed in Japanese Patent Laid-Open No. 5-118764.

The steel heating furnace disclosed in the above publication will be described with reference to FIGS. 3 and 4. The steel heating furnace F is constituted by connecting box-shaped unit furnaces 2 in series, and each unit furnace 2 is to be heated. A loading port 3 and a loading port 4 for the article W are provided,
A furnace pressure control means 5 including a duct 7 having an opening / closing damper 6 is provided on the ceiling, and the opening amount of the duct 7 is changed by operating the damper 6 to adjust the exhaust gas amount or the intake air amount. . In each unit furnace 2, a heat storage type alternating combustion burner system is arranged above and below the article W to be heated on the conveyor belt. Each heat storage body 1 of the two burners 9
A combustion air supply source for supplying combustion air to the wind box 10 via 1 and a combustion gas exhaust system are selectively connected to each burner 9, and one of the burners is supplied with combustion air through a heat storage body 11. The combustion gas is discharged from the other burner through the heat storage body 11.

In the iron and steel heating furnace, by opening and closing the furnace pressure control means 5, the combustion gas generated in each unit furnace 2 is discharged to the outside of the unit furnace 2 without flowing out to the adjacent unit furnace 2. The heat storage body 11 recovers the exhaust heat of the combustion gas and utilizes it for preheating the combustion air, and controls the combustion amount of the burner 9 to adjust the temperature in the furnace.

In the iron and steel heating furnace described above, the temperature pattern in the furnace can be arbitrarily changed by providing a regenerative burner system in each unit furnace constituting the furnace body.

[0006]

By the way, in a furnace adopting a regenerative burner such as the above-mentioned steel heating furnace,
About 80% of the total combustion gas amount is discharged through the burner for heat balance of the heat storage body and control of the furnace pressure, and the remaining about 20% is discharged from the exhaust port provided in the furnace body. Is generally installed.

However, about 20% of the combustion exhaust gas discharged from the exhaust port provided in the furnace body has a high temperature level which is the same as the furnace temperature. Therefore, if it is discharged as it is, the energy saving effect is reduced. Since the object to be heated to be charged is instantly exposed to a high temperature atmosphere, there is a concern that cracking, bending or the like may occur depending on the type of steel.

Therefore, the present invention makes effective use of high-temperature combustion exhaust gas exhausted from an exhaust port provided in a continuous heating furnace equipped with a regenerative burner, and performs rapid heating on the charging side of an object to be heated. It is intended to provide a steel heating furnace capable of preventing cracking and bending of steel materials.

[0009]

According to the present invention, in a continuous heating furnace having a regenerative burner installed, a heat exchange zone between the heated object and the exhaust gas is provided on the heated object charging side of the continuous heating furnace,
The heat exchange zone and the chimney are connected via a flue that guides the exhaust gas of the heat exchange zone, and the exhaust gas temperature measuring device on the exit side of the heat exchange zone provided in the flue is connected to the burner passage exhaust gas flow rate control means. The burner passing exhaust gas flow rate is controlled so that the exhaust gas temperature on the outlet side of the heat exchange zone is in the optimum temperature range, and the flue is provided with a control means for controlling the exhaust gas flow rate flowing through the heat exchange zone.

[0010]

In the present invention, by providing the heat exchange zone on the side of the continuous heating furnace where the article to be heated is inserted, the exhaust gas directly discharged from the furnace through the exhaust port provided in the furnace body without passing through the burner is charged. It becomes possible to exchange heat with the object to be heated,
The sensible heat of the exhaust gas can be effectively used, and the loaded object to be heated can be gently heated in this zone to prevent cracking or bending of the material which may be caused by rapid heating from cold. Further, in the present invention, the exhaust gas temperature measuring device on the outlet side of the heat exchange zone is connected to the burner passage exhaust gas flow rate control means, and the flue is a means for controlling the furnace pressure in accordance with the exhaust gas flow rate flowing through the heat exchange zone. Even if the operating conditions fluctuate, it is possible to optimize the temperature of the exhaust gas leaving the heat exchange zone by controlling the ratio of the amount of exhaust gas flowing through the heat exchange zone and the amount of exhaust gas exhausted through the burner even when operating conditions change. It is possible to achieve the highest energy-saving effect for the entire furnace while maintaining the draft range while maintaining the draft capacity.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to FIG.

The steel continuous heating furnace body F is divided into a heating zone 20 and a soaking zone 21 by a fixed partition wall 24.
The object W to be heated is transported by, for example, a walking beam mechanism.

The pass line (P.
A heat storage type burner 9 is provided above and below L), and the heat storage type burner 9 has a combustion air pipe 25 and an exhaust gas pipe 26.
Is connected. A heat exchange zone 23 for exchanging heat between the object W to be heated and the exhaust gas flowing to the charging side is provided on the charging side of the object W to be heated of the heating furnace body F, and the heat exchange zone 23 is a flue. It is connected to the chimney 28 by 27. The burner 9 is not installed in the heat exchange zone 23.

Next, referring to FIG. 2, the control system of the furnace will be described. The flue 27 is provided with a furnace pressure adjusting damper 29 and a thermocouple 30 for measuring the exhaust gas temperature. The thermocouple 30 is connected to a temperature indicating controller 31, the temperature indicating controller 31 is connected to a flow rate adjusting valve 32 provided in the exhaust gas pipe 26, and the exhaust gas is exhausted from an exhaust pipe 35 by an exhaust gas fan 34. To be done.

Explaining the operation of the heating furnace, the object to be heated charged in the heat exchange zone is heat-exchanged with the exhaust gas flowing from the furnace body, and the temperature rises gently in this zone. The sensible heat of the exhaust gas can be effectively used, and cracking and bending of the material caused by conventional rapid heating from cold can be prevented.

When the exhaust gas temperature at the outlet of the heat exchange zone is measured and the exhaust gas temperature is out of the proper temperature range, the flow rate control valve controls the flow rate of the exhaust gas discharged through the burner to control the temperature of the heating furnace. Then adjust to a predetermined temperature,
When the exhaust gas temperature at the outlet of the heat exchange zone becomes high, the flow rate control valve 3 is provided to reduce the amount of exhaust gas flowing through the heat exchange zone.
Increase the opening of 2 to adjust the exhaust gas temperature to the proper temperature range,
When the exhaust gas temperature at the outlet of the heat exchange zone becomes low, the flow rate control valve 32 is provided to increase the amount of exhaust gas flowing through the heat exchange zone.
The exhaust gas temperature is adjusted within the proper temperature range by reducing the opening degree of.

[0017]

According to the present invention, by providing a heat exchange zone on the side of the continuous heating furnace on which the object to be heated is inserted, the exhaust gas discharged directly from the furnace body to the outside of the furnace without passing through the burner is charged. Heat exchange with the heated material is possible, the sensible heat of this exhaust gas can be effectively used, and the charged material to be heated gradually rises in this zone, so the material generated by rapid heating from cold It is possible to prevent cracks and bends.

Further, in the present invention, the exhaust gas temperature measuring device on the outlet side of the heat exchange zone is connected to the burner passing exhaust gas flow rate control means, and the flue is provided with a furnace pressure according to the exhaust gas flow rate flowing through the heat exchange zone. Due to the provision of the means for controlling, even if the operating conditions change, if the ratio of the amount of exhaust gas flowing through the heat exchange zone and the amount of exhaust gas exhausted through the burner is controlled, the exhaust gas leaving the heat exchange zone It is possible to achieve the highest energy-saving effect for the entire furnace while keeping the temperature within the optimum range and ensuring draft capacity.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a heating furnace according to the present invention.

FIG. 2 is an explanatory diagram of exhaust gas control of the heating furnace of the present invention.

FIG. 3 is a schematic principle diagram of a conventional steel heating furnace.

FIG. 4 is a side view of a unit furnace of a conventional steel heating furnace.

[Explanation of symbols]

F heating furnace, W heated object, 2 unit furnace, 3 inlet, 4 outlet, 5 furnace pressure control means, 6 damper, 7 duct, 9 burner, 10 wind box, 11 heat storage body, 20 heating zone, 21 average Tropical zone, 23 heat exchange zones, 24 fixed partition walls,
25 combustion air pipe, 26 exhaust gas pipe, 27 flue, 28 chimney, 29 furnace pressure adjusting damper, 30
Thermocouple, 31 TIC, 32 Flow control valve, 34
Exhaust gas fan, 35 exhaust stack

Claims (1)

[Claims] 1. A continuous heating furnace for iron and steel in which a regenerative burner is arranged, wherein a heat exchange zone for heating an object to be heated and exhaust gas is provided on a heating object charging side of the heating furnace, and the heat exchange zone and the chimney are connected to each other. Connected via a flue that guides the exhaust gas of the heat exchange zone,
A continuous heating furnace for iron and steel equipped with a regenerative burner, characterized in that an exhaust gas temperature measuring device on the outlet side of a heat exchange zone provided in the flue is connected to a burner passing exhaust gas flow rate control means.