JP2003056840A - Waste heat using device for industrial furnace and temperature control method for it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high temperature furnace in which even when temperature in an industrial furnace exceeds 1300 deg.C, the heat exchange of waste gas can be carried out and a thermal efficiency is improved by preheating air to a temperature in the range of 800 to 1000 deg.C. SOLUTION: The industrial furnace 1 comprises an exhaust gas exhaust system 3, a combustion air supply system 4 and N sets of passage switching heat storage type heat exchangers 10. When the temperature of combustion exhaust gas in the flue 5 of the exhaust gas exhaust system of the waste heat using device of the industrial furnace 1 exceeds 1300 deg.C, the opening degree of a cooling air quantity adjusting valve 19 of a cooling air supply system 15 is adjusted by an exhaust gas temperature control means 17 upon detection of the temperature of the exhaust gas by a detecting means 16 by an exhaust gas temperature control means 17 to suck air to be cooled, control the temperature of the exhaust gas to 1300 deg.C or lower and store heat in the heat storage element 12 of the heat storage type heat exchanger. The heat storage type heat exchanger is switched to change the passage from the exhaust gas exhaust system to the combustion air supply system. Then, the combustion air of the combustion air supply system is supplied to the industrial furnace as the preheated air in the range of 800 to 1000 deg.C by the heat exchanger.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial furnace waste heat utilization apparatus provided with a flow path switching heat storage type heat exchanger in the middle of an exhaust gas discharge system and a combustion air supply system of an industrial furnace. The present invention relates to a waste heat utilization device for an industrial furnace that can use heat more efficiently, save energy, and achieve a high-temperature furnace, and a temperature control method thereof.

[0002]

2. Description of the Related Art Conventionally, as a heat exchanger for recovering high-temperature combustion waste heat, there is a trigene system. This is a system that can obtain high-temperature preheated air of 800 ° C. to 1000 ° C. by continuously exchanging heat between combustion air at normal temperature and combustion exhaust gas using alumina balls as a heat storage body.

[0003]

However, when the trigene system is applied to an industrial furnace whose internal temperature exceeds 1300 ° C., the following problems occur. A. The trigene system is designed for metal heating furnaces, and the applicable combustion exhaust gas temperature is 1300 ° C or lower in terms of heat resistance of the heat exchanger body and the switching valve. For this reason, it is not possible to directly recover heat from combustion exhaust gas exceeding 1300 ° C.
It could not be used in an industrial furnace. B. There is no example of using the trigene system to preheat combustion air from combustion exhaust gas exceeding 1300 ° C.

In order to solve the above problems, the inventor of the present invention uses a device for utilizing waste heat and cools it when the temperature (waste heat) of combustion exhaust gas discharged to the flue of an industrial furnace exceeds 1300 ° C. It is cooled to less than 1300 ° C by means and is taken into a heat storage type heat exchanger to enable high temperature heat storage.
It is possible to send high temperature preheated air from 00 ℃ to 1000 ℃ into an industrial furnace to increase the thermal efficiency and obtain a high temperature furnace with an internal temperature of 1300 ℃ or higher, which saves energy and produces high quality fired products in the high temperature furnace. It was found that it can be manufactured.
Therefore, according to the present invention, the waste heat can be efficiently used even when the temperature in the industrial furnace exceeds 1300 ° C, the energy can be saved, and the temperature of the preheated air can be increased from 800 ° C to 10 ° C.
An object of the present invention is to provide a waste heat utilization apparatus for an industrial furnace which can be a high temperature furnace having a high temperature of 00 ° C and a temperature higher than 1300 ° C, particularly 1500 ° C to 2000 ° C, and a method for controlling the temperature thereof.

[0005]

In the waste heat utilization apparatus for an industrial furnace according to claim 1 of the present invention which solves the above-mentioned problems, the base end side communicates with the flue 5 provided in the industrial furnace 1 and the front end side exhausts. An exhaust gas discharge system 3 communicating with the suction port of the fan 7, a combustion air supply system 4 having a base end side communicating with the discharge port of the air fan 8 and a tip end side communicating with the combustion air supply port of the industrial furnace 1, and an exhaust gas discharge system. 3 and the combustion air supply system 4 have a heat exchange chamber 11 that accommodates a plurality of heat storage elements 12 therein, and one connection portion of each heat exchange chamber 11 is the first flow path switching means. Exhaust gas exhaust system 3 via 13
Of the exhaust gas discharge system 3 via the second flow path switching means 14 and the other connecting portion of each heat exchange chamber 11 communicates with the upstream pipe 3a and the downstream pipe 4b of the combustion air supply system 4 in a switchable manner. The downstream pipe 3b and the upstream pipe 4a of the combustion air supply system 4 are switchably connected to each other, and the switching operation of each of the first flow path switching means and the second flow path switching means is performed by N / N of the whole process. At least 3 driving with mutually different phases
A waste heat utilization device for an industrial furnace, comprising: N or more N flow path switching heat storage type heat exchangers, the upstream pipe 3a of the exhaust gas discharge system 3 of the waste heat utilization device of the industrial furnace 1. A cooling air supply system 15 provided with a cooling air amount adjusting valve 19 for adjusting the amount of air sucked to cool the exhaust gas, and a detection means for detecting the exhaust gas temperature downstream from the cooling air supply system. 16 and an exhaust gas temperature control means 17 for opening the cooling air amount adjusting valve when the exhaust gas temperature detected by the detecting means exceeds a set temperature and closing the cooling air amount adjusting valve when the exhaust gas temperature is below the set temperature. The summary is that

The waste heat utilization apparatus for an industrial furnace according to claim 2 of the present invention is provided in the downstream side pipe 3b of the exhaust gas discharge system 3 of claim 1, and an exhaust gas amount adjusting valve 21 for adjusting the exhaust gas amount, A combustion air supply amount adjusting valve 23 provided in the upstream pipe 4a of the combustion air supply system 4 for adjusting the combustion air supply amount, and the furnace temperature of the industrial furnace are detected by the detecting means 30 to adjust the fuel supply amount. The gist is that the fuel control valve 28 for controlling the temperature is provided via the temperature control means 31.

According to a third aspect of the present invention, in the temperature control method for the waste heat utilization apparatus for the industrial furnace, the base end side communicates with the flue provided in the industrial furnace 1, and the front end side communicates with the suction port of the exhaust fan 7. The exhaust gas discharge system 3, the combustion air supply system 4 having the base end side communicating with the discharge port of the air fan 8 and the tip end side communicating with the combustion air supply port of the industrial furnace 1, the first flow path switching means 13, the second flow Exhaust gas exhaust system 3 of a waste heat utilization device of an industrial furnace 1 equipped with N-type flow path heat storage type heat exchangers 10 for switching the flow paths of the exhaust gas exhaust system and the combustion air supply system by switching operation of the path switching means 14. The temperature of the flue gas in the flue 5 is 13
When the temperature exceeds 00 ° C., when the exhaust gas temperature is detected by the detection means 16, the exhaust gas temperature control means 17 adjusts the opening degree of the cooling air amount adjustment valve 19 of the cooling air supply system 15 to suck the cooling air and exhaust gas temperature. Is controlled to a temperature of 1300 ° C. or lower to store heat in the heat storage element 12 of the heat storage type heat exchanger 10, and a switching operation of the first flow path switching means 13 and the second flow path switching means 14 of the heat storage type heat exchanger 10. After switching the flow path from the exhaust gas exhaust system 3 to the combustion air supply system 4,
The heat storage element 12 in the heat exchanger 10 that stores the combustion air supplied from the combustion air supply system 4 at the exhaust gas temperature.
The point is to send it as preheated air at 800 ° C to 1000 ° C to the industrial furnace by radiating heat.

In the waste heat utilization apparatus for an industrial furnace according to claim 1 of the present invention having the above-mentioned structure, during the heat storage operation, the first flow path switching means and the second flow path switching means are operated to operate the exhaust gas discharge system. The upstream pipe is connected to the heat exchange chamber of the heat storage heat exchanger, and the downstream pipe of the exhaust gas discharge system is connected to the heat exchange chamber. In this state, the exhaust gas discharged from the industrial furnace is discharged to the chimney via the flue, and the temperature of the exhaust gas sucked by the exhaust fan into the flue branched from the flue is detected by the detection means, and the temperature is detected. If the temperature is higher than the set temperature (allowable temperature) to be taken into the heat exchanger, open the adjustment valve of the cooling air system to suck in the cooling air and mix it, and lower the exhaust gas temperature below the set temperature to the heat exchanger. Take in and store heat in the heat storage element. The temperature of the exhaust gas taken into the heat exchanger is
Since the temperature is below the set temperature, heat exchange can be performed without causing a problem in the heat exchanger. Then, after the switching operation of the first flow path switching means and the second flow path switching means, the combustion air supplied from the air fan is released into the industrial furnace as preheated air having a higher temperature than before by the heat radiation of the heat storage element which has stored heat in the heat exchange chamber. It is possible to improve the heat transfer efficiency.

In the waste heat utilization apparatus for an industrial furnace according to claim 2 of the present invention having the above-mentioned structure, the temperature control means 31 controls the fuel control valve 28 and the combustion air supply control valve 23 to control the fuel supply amount. The supply amount of combustion air and the exhaust gas discharge amount can be linked and adjusted, and the heat exchanger of the waste heat utilization device can be adjusted by the exhaust gas amount adjustment valve 21 and the combustion air supply amount adjustment valve 23 by the temperature control means 31. It is possible to control and adjust the amount of flue gas by linking it with the amount of combustion air supplied.
Excess combustion exhaust gas is released to the atmosphere through the chimney.

According to a third aspect of the present invention having the above-mentioned structure, the method for controlling the temperature of the waste heat utilization apparatus for an industrial furnace according to the present invention is such that the temperature inside the industrial furnace exceeds 1300 ° C. and the exhaust gas temperature in the flue of the exhaust gas discharge system is high. When the temperature exceeds 1300 ° C., the temperature of the exhaust gas is detected by the detection means, and the temperature control means adjusts the opening degree of the cooling air amount adjusting valve of the cooling air supply system to suck the cooling air and mix it with the exhaust gas. The exhaust gas temperature is controlled to 1300 ° C. or lower, which is a temperature (set temperature) that can be taken into the heat exchanger, and is taken into the heat storage type heat exchanger to store heat at a high temperature in the heat storage element, and the first flow of the heat storage type heat exchanger. After the switching operation from the exhaust gas discharge system to the combustion air supply system by the switching operation of the path switching means and the second flow path switching means, the heat storage energy in the heat exchanger that stores the combustion air supplied by the combustion air supply system at the exhaust gas temperature. From 800 ℃ by the radiation of the instrument 1
It can be fed into an industrial furnace as preheated air at a high temperature of 000 ° C. Therefore, the thermal efficiency is improved and the temperature inside the furnace is reduced to 13
It is possible to raise the temperature to higher than 00 ° C and save energy. That is, according to the temperature control method of the present invention, the preheated air is heated from 800 ° C. to 10 ° C. in the heat storage type heat exchanger.
Since it is sent to the furnace as a high temperature of 00 ° C., it is possible to provide a high temperature furnace of over 1300 ° C., particularly a high temperature furnace of 1500 to 2000 ° C. Further, even if the exhaust gas temperature is higher than 1300 ° C., it is cooled and lowered to the set temperature of 1300 ° C. or lower. Therefore, the N-type heat storage type heat exchanger used in the present invention may cause a problem. Absent.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of a waste heat utilization device of a firing furnace as a waste heat utilization device of an industrial furnace of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a waste heat utilization device of a firing furnace of the present invention, FIG. 2 is an enlarged view of the waste heat utilization device, FIG.
[Fig. 3] is an enlarged view of a firing furnace.

1 to 3, the firing furnace 1 is provided with a burner 2 at the top of the furnace, an exhaust gas discharge system 3 is connected to the side thereof, and a combustion air supply system 4 is connected to the burner 2 at the top of the furnace. ing. A chimney 6 is provided on a side flue 5 of the firing furnace 1. The flue 5 is branched on the way, and one flue serves as a chimney 6 and the other flue serves as an exhaust gas discharge system 3 that utilizes waste heat. The exhaust gas discharge system 3 has a flue 5 branching in the middle of the flue 5 at the base end side and at the tip end at the suction port of the exhaust fan 7. Negative pressure due to suction is applied to the exhaust gas exhaust system during operation of the exhaust fan. The exhaust gas discharge system 3 uses the waste heat to store the heat in the heat storage type heat exchanger 1.
Pass 0. 3a is a flue gas exhaust system 5 and a heat exchanger 10.
The upstream pipe 3b is a downstream pipe between the heat exchanger 10 and the exhaust fan. Further, the combustion air supply system 4 has its base end side connected to the discharge port of the air fan 8 and its front end side connected to the combustion air supply port of the industrial furnace. Combustion air supply system 4
When the air fan 8 is operating, combustion air is supplied to the combustion furnace by air pressure supplied by the fan. The combustion air supply system 4 also passes through the heat exchanger to utilize waste heat. 4a is an upstream pipe between the air fan of the combustion air supply system and the heat exchanger 10,
b is a downstream pipe between the heat exchanger and the industrial furnace. The combustion air supply port of this industrial furnace is, for example, the air intake port 2a of the burner 2 of the firing furnace 1. In addition, in order to utilize the heat of the exhaust gas discharged to the chimney 6, it is preferable to provide various preheating utilization devices in association with the chimney. For example, as a preheating utilization device that utilizes high-temperature exhaust gas from the chimney 6,
The chimney may be provided with a material preheating device, a hot water producing device, or the like, and the exhaust gas can be effectively used for preheating the material, producing hot water, and the like to save energy.

At least three heat storage type heat exchangers 10 are provided in parallel in the middle of the exhaust gas discharge system 3 and the combustion air supply system 4, and the first flow path switching means 13 and the second flow path switching means are respectively provided. It is connected through 14. The first flow path switching means and the second flow path switching means are switched to switch to either the flow path of the exhaust gas discharge system or the flow path of the combustion air supply system. The switching operation of the first flow path switching means 13 and the second flow path switching means 14 is operated with a phase difference of 1 / N during the whole process. The embodiment is a case where three heat storage type heat exchangers 10 are used in the trigene system, and the switching operation of the first flow path switching means 13 and the second flow path switching means 14 is performed by one third of the whole process. They drive with different phases.

Each heat storage type heat exchanger 10 includes an exhaust gas discharge system 3
And a heat exchange chamber 11 that forms a ventilation path of the combustion air supply system 4, and a plurality of heat storage elements 12 that are heat exchange elements that receive and release heat are housed inside the heat exchange chamber 11. . The heat storage element 12 is made of a refractory material (ceramic material), a metal, a mixed material of a refractory material and a metal, and has a diameter of 10 mm.
mm ~ φ50mm spherical particles and one side 10mm ~ 50m
m is a prism or a hollow prism, or a honeycomb ceramic is a porous body, and the honeycomb ceramic has a cell pitch of 2.54 mm and a partition wall thickness of about 0.43 mm. The heat storage element 12 is not limited to a spherical shape, a prismatic body, or the like as long as it can have a good thermal conductivity, and various types such as a porous body or a heat transfer fin on the outer peripheral surface can be used. The shape is conceivable. Heat exchanger 10
If a ceramic ball is used as the spherical particle of the heat storage element that is allowed to stand in the heat exchange chamber 11, the life thereof is semi-permanent. The heat exchange chamber is provided with an outlet for replacing the spherical particles, and when the spherical particles become dirty, they can be taken out, washed and reused.

The first flow path switching means 13 includes a first opening / closing valve 13a for controlling the connection between the heat storage type heat exchanger 10 and the upstream pipe 3a of the exhaust gas discharge system 3, the heat storage type heat exchanger 10 and combustion air supply. Second for controlling the connection of the system 4 with the downstream pipe 4a
An opening / closing valve 13b, and by operating the first opening / closing valve 13a and the second opening / closing valve 13b, the flow path connected to the heat storage heat exchanger 10 is switched to either the combustion air supply flow path or the exhaust gas discharge flow path. It is a thing.

The second flow path switching means 14 includes a third opening / closing valve 14a for controlling the connection between the heat storage type heat exchanger 10 and the downstream pipe 3b of the exhaust gas discharge system 3, the heat storage type heat exchanger 10 and the combustion air. A fourth opening / closing valve 14b for controlling connection with the upstream pipe 4b of the supply system 4, and a third opening / closing valve 14a.
By operating the fourth opening / closing valve 14b, the flow path connected to the heat storage heat exchanger 10 is switched to either the combustion air supply flow path or the exhaust gas discharge flow path.

The switching operation of each of the first flow path switching means 13 and the second flow path switching means 14 of the three heat storage type heat exchangers 10 is switched by mutually making a phase difference of one third of the whole process. In operation, the three heat storage heat exchangers 10 are operated with a phase difference of one-third of the whole process. The switching operation of each of the first flow path switching means and the second flow path switching means is automatically or manually switched based on a program by the control device.

In the industrial furnace waste heat utilization apparatus of the present invention, as described above, the exhaust gas discharge system 3 is connected such that the base end side communicates with the flue 5 provided in the industrial furnace 1 and the tip end side communicates with the suction port of the exhaust fan 7. And a combustion air supply system 4 having a base end side communicating with a discharge port of an air fan 8 and a tip end side communicating with a burner 2 of an industrial furnace 1, and an exhaust gas discharge system 3 and a combustion air supply system 4 are provided midway. Multiple heat storage elements 12 inside
Has a heat exchange chamber 11 accommodating therein, and one connection portion of each heat exchange chamber 11 is connected to the upstream side pipe 3a of the exhaust gas discharge system 3 and the downstream side of the combustion air supply system 4 via the first flow path switching means 13, respectively. The heat exchange chamber 11 is connected to the side pipe 4b in a switchable manner, and the other connecting portion of each heat exchange chamber 11 is connected to the downstream pipe 3b of the exhaust gas discharge system 3 and the upstream side of the combustion air supply system 4 via the second flow path switching means 14, respectively. Three units that are connected to the pipe 4a so as to be switchable and that are operated by switching the first flow path switching unit 13 and the second flow path switching unit 14 with a phase difference of one-third of the entire process. A waste heat utilization apparatus for an industrial furnace, comprising: the flow path switching type heat storage type heat exchanger 10;
A detection means 16 and an exhaust gas temperature control means 17.

1 to 3, the cooling air supply system 1 is shown.
Reference numeral 5 branches a flue 5 communicating with a chimney 6 of the industrial furnace 1, and an air supply pipe 15a is connected to the midway of the branched flue 5, that is, an upstream pipe 3a of the exhaust gas discharge system 3 so as to communicate therewith. It In the embodiment, the air supply pipe 15a is provided in the direction orthogonal to the branched flue 5. Since the exhaust gas exhaust system is under suction negative pressure by the exhaust fan 8, outside air at room temperature (about 20 ° C., room temperature) is sucked into the air supply pipe for cooling. A cooling air amount adjusting valve 19 for adjusting the amount of air sucked into the air supply pipe 15a to cool the high temperature exhaust gas is pivotally supported by a control motor 20 so as to be openable and closable, and the control motor 20 is controlled by the exhaust gas temperature control means. 17, the control motor 20 is moved by the command, and the adjustment valve 1 is provided.
9 is opened and closed to variably adjust the suction amount of air in the air supply pipe. A thermocouple is used as the exhaust gas temperature detection means 16, and an exhaust gas temperature controller (TIC) is used as the exhaust gas temperature control means 17.

The exhaust gas temperature controller 17 is connected to the exhaust gas exhaust system 3 downstream of the cooling air supply system 15 by a wire to a thermocouple 16 for detecting the exhaust gas temperature and a control motor 20 of the cooling air amount adjusting valve 19. In the embodiment, a thermocouple 16 is provided facing the inside of the exhaust gas pipe at a position downstream of the cooling air supply system 15 of the branched flue 5 and up to the flow path switching means of the heat storage heat exchanger. The thermocouple is connected to the exhaust gas temperature controller 17, the exhaust gas temperature controller 17 determines the exhaust gas temperature detected by the thermocouple, and a signal is sent to the control motor 20 to detect the exhaust gas temperature by the thermocouple 16. When the temperature exceeds the set temperature, the cooling air amount adjusting valve 19 is opened, and when the temperature is below the set temperature, the cooling air amount adjusting valve 19 is closed. In the case of this embodiment, the heat storage type heat exchanger 1
Since the set temperature of the exhaust gas to be taken into it is set to 1300 ° C or less in advance due to the structure, material, etc. of 0, if the temperature of the combustion exhaust gas exceeds 1300 ° C, set it to the thermocouple 1
6, the exhaust gas temperature controller 17 makes a judgment and a signal opens the cooling air amount adjusting valve 19 to suck air at room temperature for cooling, and the exhaust gas temperature exceeding 1300 ° C. is set to 1300 ° C. It can be lowered below ℃.

There is a correlation between the amount of exhaust gas and the amount of combustion air. If, in an unexpected situation, the amount of exhaust gas sucked by the exhaust gas fan 8 increases and the correlation with the combustion air amount collapses, the combustion air temperature rises above the planned value, which may cause malfunctions in various combustion control devices. There is a nature. Further, in the opposite case, that is, when the suction amount of the exhaust gas fan 8 decreases, the combustion air temperature becomes lower than the planned value and the energy saving rate decreases.

In the temperature control device of the present invention, in order to solve this, an exhaust gas amount adjusting valve 21 provided in the downstream pipe 3b of the exhaust gas exhaust system 3 for adjusting the exhaust gas amount.
And a combustion air supply amount adjusting valve 23 provided in the upstream pipe 4a of the combustion air supply system 4 for adjusting the combustion air supply amount.
And a fuel adjusting valve 28 for detecting the temperature inside the industrial furnace by the detecting means 30 and adjusting the fuel supply amount, are provided via a temperature control means (TIC) 31.

Reference numeral 21 is an exhaust gas amount adjusting valve for adjusting the amount of exhaust gas, which is provided downstream of the heat exchanger 10 and in the downstream pipe 3b of the exhaust gas discharge system 3 upstream of the exhaust fan 8. 23
Is a combustion air supply amount adjusting valve for adjusting the combustion air supply amount, and is provided in the upstream pipe 4a of the combustion air supply system 4 between the air fan 7 and the heat exchanger 10. The exhaust gas amount adjusting valve 21 is provided with a control motor 22, and the combustion air supply amount adjusting valve 23 is provided with a control motor 24. The control motors 22 and 24 are connected to the temperature control means 31 by a wire 25. The control motor 22 of the exhaust gas amount adjusting valve 21 and the combustion air supply amount adjusting valve 2 are instructed by the temperature control means 31.
3 control motor 24, and a fuel adjustment valve 28 described later.
The control motor 29 is controlled. Alternatively, the control motor 22 of the exhaust gas amount adjusting valve 21 and the combustion air supply amount adjusting valve 2
It is also possible to provide an interlocking mechanism with the control motor 24 of No. 3 so as to be able to co-operate, and connect the interlocking mechanism to the temperature control means 31. In this way, the exhaust gas amount adjustment valve 21
And the combustion air supply amount adjusting valve 23 are linked to each other, and opening / closing control can be simultaneously performed by a command from the temperature control means 31.

Reference numeral 27 denotes a fuel supply system for supplying fuel to an industrial furnace such as a firing furnace, which is provided with a fuel adjusting valve 28, and a control motor 29 of the adjusting valve is connected to a temperature control means 31 by a wiring 32. As the fuel, either gas fuel such as city gas 13A or liquid fuel can be used. Further, 30 is a detection means for measuring the temperature in the combustion chamber of an industrial furnace such as a firing furnace,
As the detection means, a thermocouple is provided facing the inside of the furnace. The detection means 30 is connected to the temperature control means 31 by a wiring 33. Reference numeral 31 is a temperature control means, which is a temperature controller in the embodiment, is connected to the detection means 30 and is connected to the control motor 29 of the fuel adjusting valve 28 provided in the fuel supply system 27 by the wiring 32. Then, when the temperature inside the furnace is lower than the set temperature by the detection means 30, the fuel adjusting valve 28 is opened by the command of the temperature controller to increase the fuel and raise the temperature inside the furnace. In addition, the temperature control means 31 includes the control motor 22 for the exhaust gas amount adjusting valve 21, as described above.
The control motor 24 of the combustion air supply amount adjusting valve 23 is connected by wiring. The temperature inside the industrial furnace is controlled by linking the fuel supply amount, the combustion air supply amount, and the exhaust gas discharge amount. Therefore, the fuel adjustment valve is opened / closed according to the temperature in the furnace, the combustion air supply amount adjustment valve 23 is opened / closed according to the increase / decrease of the fuel, the combustion air amount is increased / decreased, and the exhaust gas amount adjustment valve 21 is opened / closed. Increase or decrease the amount of exhaust gas. When the combustion amount is increased or decreased according to the increase or decrease in the temperature of the furnace, the combustion air amount also follows it, and it is possible to operate at a constant air ratio. For example, when the temperature inside the furnace is measured by the thermocouple 30 and when the temperature falls below the preset temperature when burning at a preset furnace temperature of 1800 ° C., the fuel controller 28 is opened by the temperature controller 31. The amount of fuel is increased to raise the temperature to the set temperature, and the supply amount of combustion air and the exhaust gas amount are increased accordingly. It is possible to keep the combustion of the furnace good at all times. Further, the adjustment of the heat exchanger of the waste heat utilization device links the suction amount of the combustion exhaust gas amount with the supply amount of the combustion air amount, and releases the surplus combustion exhaust gas from the chimney to the atmosphere. The supply amount of the combustion air amount is also increased / decreased according to the increase / decrease of the suction amount of the combustion exhaust gas. Since the amount of combustion air supplied and the amount of exhaust gas discharged can be made constant,
It is possible to prevent malfunction of the heat exchanger without the combustion air temperature becoming higher than the planned value. Again,
If the suction amount of exhaust gas fan increases due to an unexpected situation, open the combustion air amount adjustment valve to increase the combustion air amount and maintain the combustion air temperature at the planned value in order to maintain the correlation with the combustion air amount. , Make sure that various combustion control devices do not malfunction.

The temperature control method for the waste heat utilization device of the industrial furnace is as follows:
Exhaust gas discharge system 3 whose base side communicates with the flue 5 provided in the industrial furnace 1 and whose tip side communicates with the suction port of the exhaust fan 7.
And a combustion air supply system 4, the base end side of which communicates with the discharge port of the air fan 8 and the tip end side of which communicates with the combustion air supply port of the industrial furnace, the first flow path switching means 13, and the second flow path switching means 1
Exhaust gas temperature in the flue of the exhaust gas exhaust system of the industrial furnace waste heat utilization device equipped with three flow path switching heat storage type heat exchangers that switch the flow paths of the exhaust gas exhaust system and the combustion air supply system by switching operation of No. 4 Temperature exceeds about 1300 ° C., when the temperature of the exhaust gas is detected by the detecting means, the exhaust gas temperature control means 17 adjusts the opening degree of the cooling air amount adjusting valve 19 of the cooling air supply system 15 to suck the cooling air. The mixture is mixed and the temperature of the exhaust gas is controlled to 1300 ° C. or lower to store heat in the heat storage element 12 of the heat exchanger 10, and the first flow path switching means 13 and the second flow path switching means 14 of the heat storage type heat exchanger 10 are mixed. After the switching operation from the exhaust gas exhaust system 3 to the combustion air supply system 4 by the switching operation of the above, the heat is dissipated by the heat storage element 12 in the heat exchanger that stores the combustion air supplied by the combustion air supply system 4 at the exhaust gas temperature. From 00 ° C. it can be fed to the industrial furnace 1 as 1000 ° C. preheated air. Therefore, the thermal efficiency of the industrial furnace is improved to save energy, and the temperature inside the furnace is increased to 130
It can be a high temperature furnace above 0 ° C., especially 1500 ° C. to 2000 ° C. The upper limit of this high temperature furnace is 200
It is not limited to 0 ° C. In the firing furnace, the temperature exceeds that of unfired products such as ceramics by 1300 ° C, for example, 1800
By stably firing at a high temperature of ℃, it is possible to produce a high-quality fired product. When the exhaust gas temperature of the flue 5 is 1300 ° C. or less, the intake of the cooling air is stopped, the combustion air temperature that maintains a constant ratio with the exhaust gas temperature at that time is obtained, and highly efficient energy saving can be achieved. Therefore, according to this temperature control method, it is possible to recover the waste heat of the combustion exhaust gas of the industrial furnace in which the temperature inside the furnace exceeds 1300 ° C., and the combustion air supplied by the combustion air supply system by heat exchange is changed from 800 ° C. to 1000 ° C. Can be sent to the industrial furnace as preheated air. Therefore, with the above configuration and exclusive combustion of city gas (13A),
For example, heating at a high temperature exceeding 1500 ° C. is possible. Also, by adjusting the cooling air amount and the combustion exhaust gas suction amount,
Any preheated air temperature can be obtained within a certain range.

The operation of the above configuration will be described below. The heat storage operation and the heat radiation operation in each heat storage type heat exchanger are the same. Here, one heat storage type heat exchanger 10
The action of will be described.

During the heat storage operation, the first opening / closing valve 13a of the first flow path switching means 13 is opened, the second opening / closing valve 13b is closed, and the third opening / closing valve 14a of the second flow path switching means 14 is opened. The fourth opening / closing valve 14b is closed, the upstream pipe 3a of the exhaust gas discharge system 3 is connected to the heat exchange chamber 11 of the heat storage heat exchanger 10, and the downstream side 3b of the exhaust gas discharge system 3 is connected to the heat exchange chamber 11. To do.

In this state, the temperature of the high-temperature exhaust gas discharged to the flue branched from the flue 5 of the firing furnace 1 is, for example, 1800 ° C.
In the case of, when the temperature is detected by the thermocouple 16, the cooling air adjusting valve 19 of the air supply pipe is opened by the control motor by the command of the temperature controller 17 and the cooling air is sucked by the negative pressure suction force of the exhaust gas fan, 130 when mixed with high temperature exhaust gas
It is lowered to 0 ° C. and taken into the heat exchanger 10.
The exhaust gas at 1300 ° C. passes through the gaps between the plurality of heat storage elements that form the heat exchange element of the heat exchange chamber, and the heat storage element stores high temperature heat. The temperature of the exhaust gas that has passed through the heat storage element drops to about 200 ° C. (170 ° C. in the figure), and is attracted by the suction negative pressure of the exhaust fan to be discharged from the heat exchange chamber through the downstream side pipe of the exhaust gas discharge system.

On the other hand, at the time of heat radiation operation, the first opening / closing valve 13a of the first flow path switching means 13 is closed, the second opening / closing valve 13b is opened, and the third flow path switching means 14 is opened.
The fourth opening / closing valve 1 is provided while closing the opening / closing valve 14a.
4b is opened, the upstream side pipe 4b of the combustion air supply system 4 is connected to the heat exchange chamber 11 of the heat storage type heat exchanger 10, and
Combustion air supplied from air fan 7 (outside air, room temperature about 20
C) flows into the heat exchange chamber 11 of the heat storage type heat exchanger 10 through the upstream pipe 4b of the combustion air supply system 4, and the heat exchange chamber 1
The heat radiated by the heat storage element 12 is removed through the gap between the plurality of heat storage elements 12 housed in
Air heated to 0 ° C. and preheated to 900 ° C. is sent from the heat exchange chamber to the burner of the firing furnace through the downstream side pipe 4 a of the combustion air supply system 4.

The three heat storage type heat exchangers perform repetitive heat storage operation and heat radiation operation mutually differently. For example, N
o. When the heat storage type heat exchanger 10 of No. 1 is performing heat storage operation (heating), No. The heat storage type heat exchanger 10 of No. 2 is in the latter half of the process of the heat radiation operation (blowing), and No. The heat storage type heat exchanger 10 of 3 is in the first half process of the heat radiation operation (blowing).

In a state in which one heat exchanger 10 is operated to store heat, the other heat storage type heat exchanger 10 is operated to radiate heat.
The heat exchange between the exhaust gas and the combustion air via the heat storage element 12 can be continuously performed. It is possible to constantly supply stable combustion air at 900 ° C. to the burner of the firing furnace. Since the three heat storage type heat exchangers 10 are operated with a phase difference of one-third of the entire process, a decrease in the blast temperature due to a decrease in the heat radiation amount in the latter half of the heat radiation operation of the heat exchanger can be reduced by other factors. This can be compensated by the abundant amount of heat radiation in the first half of the heat radiation operation of the heat storage type heat exchanger 10, and the temperature change of the combustion air can be reduced. In the embodiment, the case where the temperature of the combustion air is raised to 900 ° C. by the heat radiation of the heat exchanger has been described, but the temperature of the combustion air can be raised from 800 ° C. to 1000 ° C.

Although one example of the embodiment of the present invention has been described above, the present invention is not limited to the embodiment and can be implemented in various forms without departing from the scope of the present invention. Of course.
Although the firing furnace has been described in the embodiment, the present invention is not limited to this, and can be applied to various industrial furnaces such as a metal heating furnace, a glass heating furnace, a cupola, and a kiln for ceramics.

[0033]

The present invention is carried out in the form described above, and has the following effects.

In the waste heat utilization apparatus for an industrial furnace of the present invention, during the heat storage operation, when the exhaust gas temperature is higher than the set temperature (permissible temperature) in the flue of the exhaust gas exhaust system of the industrial furnace, the regulating valve of the cooling air supply system is used. To cool the air by sucking in the air to be cooled and taking the temperature of the exhaust gas into the heat exchanger as a temperature equal to or lower than the set temperature. After the switching operation of the first flow path switching means and the second flow path switching means, the air fan is removed from the air fan. The supplied combustion air is sent to the industrial furnace at a higher temperature than before due to the high-temperature heat accumulated in the heat exchange chamber, which improves thermal efficiency and saves energy with this heat exchanger compared to the conventional metal heat exchanger. Compared with this, it is possible to save energy about twice.

Further, the waste heat utilization device of the industrial furnace can increase or decrease the supply amount of fuel according to the increase or decrease of the temperature inside the furnace to maintain the temperature inside the furnace at the set temperature of the furnace, and the temperature control means can control the fuel. The flow rate can be adjusted by adjusting the openings of the adjustment valve, the combustion air supply amount adjustment valve, and the exhaust gas amount adjustment valve, and the fuel supply amount, the combustion air amount, and the exhaust gas suction amount can be linked and adjusted. It is possible to keep the combustion in the furnace good at all times, and to prevent the heat exchanger from malfunctioning by making the exhaust gas suction amount and the combustion air amount constant.

According to the temperature control method for the waste heat utilization apparatus of the industrial furnace of the present invention, when the temperature inside the industrial furnace and the temperature of the exhaust gas in the flue exceed 1300 ° C., the cooling air supply system is provided by the temperature control means. The cooling air amount adjusting valve is adjusted to open the cooling air by adjusting the opening of the cooling air amount adjusting valve to set the exhaust gas temperature to 1300
It can be taken into a heat exchanger as a temperature of ℃ or less and stored in a heat storage element at high temperature, and waste heat of combustion exhaust gas of an industrial furnace whose temperature in the furnace exceeds 1300 ° C can be recovered. And,
The combustion air supplied by the combustion air supply system by heat exchange is
It can be fed into an industrial furnace as preheated air from 00 ° C to 1000 ° C. Therefore, with the exclusive use of city gas (13A),
High temperature heating is possible. Further, by adjusting the cooling air amount and the combustion exhaust gas suction amount, it is possible to obtain an arbitrary preheated air temperature within a certain range.

[Brief description of drawings]

FIG. 1 is a copy diagram of an industrial furnace waste heat utilization apparatus of the present invention.

FIG. 2 is an enlarged view of the heat storage type heat exchanger of the industrial furnace waste heat utilization apparatus of the present invention.

FIG. 3 is an enlarged view of a firing furnace of a waste heat utilization device of the industrial furnace.

[Explanation of symbols]

1 firing furnace 3 Exhaust gas exhaust system 4 Combustion air supply system 5 flue 6 chimney 7 exhaust fan 8 air fans 10 Heat storage type heat exchanger 11 heat exchange room 12 Heat storage element 13 First flow path switching means 14 Second flow path switching means 15 Cooling air supply system 16 Detection means 17 Exhaust gas temperature control means 19 Cooling air amount adjustment valve 21 Exhaust gas amount adjustment valve 23 Combustion air amount control valve 28 Fuel adjustment valve 30 Detection means 31 temperature control means

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshihide Ichikawa             20 Kamijinya-cho, Seto City, Aichi Prefecture             Inside Rita Techno (72) Inventor Yoshihiro Nakamura             2 Toho Gas Co., Ltd., 507, Shinbaocho, Tokai City, Aichi Prefecture             Inside the company (72) Inventor Susumu Yamada             2 Toho Gas Co., Ltd., 507, Shinbaocho, Tokai City, Aichi Prefecture             Inside the company F term (reference) 3K023 QA18 QB02 QB18 QB19 QB20                       QC01 QC08                 3K070 DA09 DA47 DA50 DA58 DA64                       DA66 DA75

Claims (3)

[Claims] 1. An exhaust gas discharge system having a base end side communicating with a flue provided in an industrial furnace and a tip end side communicating with an exhaust fan suction port, and a base end side communicating with an air fan discharge port and a tip end side being an industrial furnace. Is installed in the middle of the combustion air supply system, the exhaust gas discharge system and the combustion air supply system,
A heat exchange chamber having a plurality of heat storage elements accommodated therein is provided, and one connection portion of each heat exchange chamber is connected to the upstream side pipe of the exhaust gas discharge system and the downstream side of the combustion air supply system via the first flow path switching means. Switchable communication with the side pipe, and the other connection part of each heat exchange chamber is switchably connected with the downstream pipe of the exhaust gas discharge system and the upstream pipe of the combustion air supply system via the second flow path switching means. And each first flow path switching means, second
An industrial furnace equipped with at least three or more N flow path switching heat storage type heat exchangers which are operated so that the switching operation of the flow path switching means is different from each other with a phase difference of 1 / N in the whole process. A waste heat utilization device, which is provided in an upstream pipe of an exhaust gas discharge system of the waste heat utilization device of the industrial furnace, and is provided with a cooling air amount adjusting valve for adjusting an amount of air sucked to cool the exhaust gas. A cooling air supply system, detection means for detecting the exhaust gas temperature downstream of the cooling air supply system, and when the exhaust gas temperature detected by the detection means exceeds a set temperature, the cooling air amount adjusting valve is opened and set. A waste heat utilization device for an industrial furnace, comprising: an exhaust gas temperature control means for closing the cooling air amount adjusting valve when the temperature is equal to or lower than the temperature. 2. An exhaust gas amount adjusting valve which is provided in a downstream pipe of the exhaust gas exhaust system and adjusts an exhaust gas amount, and a combustion which is provided in an upstream pipe of the combustion air supply system and adjusts a combustion air supply amount. 2. An air supply amount adjusting valve and a fuel adjusting valve for adjusting the fuel supply amount by detecting with a detecting means for detecting the temperature inside the furnace of the industrial furnace are provided through the temperature control means. Waste heat utilization equipment for industrial furnaces. 3. An exhaust gas exhaust system having a base end side communicating with a flue provided in an industrial furnace and a tip end side communicating with an exhaust fan suction port, and a base end side communicating with an air fan discharge port and a tip end side being an industrial furnace. Of the combustion air supply system that communicates with the combustion air supply port, and the flow paths of the exhaust gas discharge system and the combustion air supply system by switching the first flow path switching means and the second flow path switching means. When the temperature of the combustion exhaust gas in the flue of the exhaust gas discharge system of the waste heat utilization device of the industrial furnace equipped with the heat storage type heat exchanger exceeds 1300 ° C, the exhaust gas temperature is cooled by the exhaust gas temperature control means when detected by the detection means. The opening of a cooling air amount adjusting valve of the air supply system is adjusted to suck the cooling air to control the exhaust gas temperature to 1300 ° C. or less and take it into the heat storage type heat exchanger to store heat in the heat storage element, Heat storage After switching the flow path from the exhaust gas discharge system to the combustion air supply system by the switching operation of the first flow path switching means and the second flow path switching means of the heat exchanger, the combustion air supplied by the combustion air supply system is changed to the exhaust gas. A method for controlling the temperature of a waste heat utilization device for an industrial furnace, characterized in that preheated air at 800 ° C to 1000 ° C is sent to the industrial furnace by heat radiation from a heat storage element in a heat exchanger that has stored heat at a temperature.