JPH1054676A - Waste heat utilizing device for industrial furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste heat utilizing device for a cupola, which is increased in a temperature efficiency, improved in the durability of the same by eliminating the factors of abrasion and prevented from generating noise and vibration by utilizing high-temperature waste gas as heating fluid. SOLUTION: A heat storage type heat exchanger 6 is provided with a heat exchanging chamber 9, having therein a plurality of heat storage elements 10 or heat exchanging elements effective the reception and radiation of heat stationary, while one side port of the heat exchanging chamber 9 is communicated with the upstream side pipeline 2a of a waste gas discharging system 2 as well as the downstream side pipeline 3a of a combustion air supplying system 3 switchably through a first flow direction control means 7 and the other side port of the heat exchanging chamber 9 is communicated with the constrain side pipeline 2b of the waste gas discharging system 2 as well as the upstream side pipeline 3b of the combustion air supplying system 3 switchably through a second flow direction control means 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an energy saving technique for efficiently using energy in a cupola, and more particularly to an apparatus for utilizing waste heat of an industrial furnace such as a cupola.

[0002]

2. Description of the Related Art Conventionally, in an industrial furnace such as a cupola used for the production of cast iron, exhaust gas discharged from the furnace top is guided to a waste heat boiler to recover waste heat as steam, or the exhaust gas is converted into a heat exchanger. And use the recovered heat as a heating source for combustion air. Such a heat exchanger includes a metal heat exchange tube and a regenerative heat exchanger. As the metal heat exchange tube, for example, there is a double structure type consisting of an outer cylinder and an inner cylinder, and while allowing exhaust gas to flow through a high-temperature flow path formed by the inner cylinder, between the inner cylinder and the outer cylinder. The combustion air is circulated in the low-temperature flow path to be formed in a direction facing the exhaust gas, and the heat of the exhaust gas is transferred to the combustion air through the 99-fold cylindrical wall of the inner cylinder. As a heat storage type heat exchanger, for example, the flow path inside the tower is divided into an upper gas section and a lower wind section, and ceramic pellets as a heat storage material are passed through the gas section and the wind section from the tower top to the tower bottom. In the gas section, the heat of the exhaust gas is received by the ceramic pellet by allowing the exhaust gas to flow in the gas pellet in the flow direction of the ceramic pellet, and the combustion air in the wind section faces the flow direction of the ceramic pellet. The heat of the ceramic pellets is radiated to the combustion air by circulating it. The ceramic pellets that have reached the bottom of the tower are again lifted to the top of the tower through the circulation duct and circulated.

[0003]

However, in the above metal heat exchange tube, the upper limit of the hot air temperature is limited to about 500 ° C. because the constituent members are metal, and the exhaust gas discharged from the cupola is cooled. After reducing the temperature to an appropriate temperature, it was necessary to guide the mixture to a heat exchanger. For this reason, there has been a problem that the amount of heat that can be recovered is limited. Also,
In the regenerative heat exchanger, since the ceramic pellets are circulated through the circulation duct, there has been a problem that abrasion of the circulation duct, abrasion of the ceramic pellet itself, noise and vibration occur.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and uses a high-temperature exhaust gas as a heating fluid to increase temperature efficiency, eliminate wear factors, increase durability, and reduce noise and vibration. An object of the present invention is to provide a waste heat utilization device for a furnace.

[0005]

In order to solve the above-mentioned problems, a waste heat utilizing apparatus for an industrial furnace according to the present invention has a base end communicating with a furnace top of an industrial furnace such as a cupola and a tip end of an exhaust blower. An exhaust gas discharge system that communicates with the suction port, a combustion air supply system whose base end communicates with the discharge port of the combustion air blower and a distal end that communicates with the tuyere of the industrial furnace, and an exhaust gas discharge system and a combustion air supply system A regenerative heat exchanger that is interposed, and the regenerative heat exchanger has a heat exchange chamber in which a plurality of heat storage elements forming a heat exchange element that receives and radiates heat are placed. One connection of the exchange chamber is switchably connected to the upstream pipe of the exhaust gas discharge system and the downstream pipe of the combustion air supply system via the first flow path switching means, and the other connection of the heat exchange chamber is connected to the first pipe. Downstream piping of exhaust gas discharge system via two flow path switching means The preliminary combustion air supply system upstream pipe is obtained by a switchably communicating configuration.

With the above configuration, during the heat storage operation, the first flow path switching means and the second flow path switching means are operated to connect the upstream pipe of the exhaust gas discharge system to the heat exchange chamber of the heat storage type heat exchanger. Then, the downstream pipe of the exhaust gas discharge system is connected to the heat exchange chamber. In this state, the high-temperature exhaust gas discharged from the furnace top of the industrial furnace flows into the heat exchange chamber of the regenerative heat exchanger through the exhaust gas discharge system, and is interposed between the plurality of heat storage elements forming the heat exchange element that is settled in the heat exchange chamber. After the heat storage element is heated, the heat is attracted by the suction negative pressure of the exhaust blower and flows out of the heat exchange chamber to the downstream pipe of the exhaust gas discharge system. During this time, the heat storage element of the heat storage type heat exchanger can store high-temperature heat by receiving heat from the exhaust gas in the high-temperature range, thereby improving the temperature efficiency.

[0007] During the heat radiation operation, the first flow path switching means and the second flow path switching means are operated to connect the upstream pipe of the combustion air supply system to the heat exchange chamber of the regenerative heat exchanger and to supply the combustion air. Connect the downstream piping of the system to the heat exchange chamber. In this state, the combustion air supplied from the combustion air blower flows into the heat exchange chamber of the regenerative heat exchanger through the combustion air supply system, and flows between the plurality of heat storage elements forming the heat exchange element that is stationary in the heat exchange chamber. After circulating through the gap and taking the heat radiated by the heat storage element to raise the temperature, the heat flows from the heat exchange chamber through the downstream pipe of the combustion air supply system into the industrial furnace through the tuyere.

Therefore, during the heat storage operation and the heat radiation operation, the heat storage element receives and radiates heat between the exhaust gas and the combustion air in a stationary state, so that the conventional wear of the circulation duct and the wear of the heat storage element itself. And noise and vibration do not occur.

Further, by connecting a plurality of regenerative heat exchangers in parallel to the exhaust gas discharge system and the combustion air supply system, one regenerative heat exchanger can be operated while another regenerative heat exchanger is operated. The heat exchange operation can be performed between the exhaust gas and the combustion air through the heat storage element by performing the heat storage operation and the heat radiation operation repeatedly performed in each regenerative heat exchanger differently from each other. It can be performed continuously, and combustion air at a stable temperature can always be supplied to the tuyere of the industrial furnace.

The heat storage element is made of a heat-resistant member such as a honeycomb ceramic having a porous body or a ceramic ball having a particle diameter of 10 mm to 50 mm. The rate is favorable.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1 and FIG.
Has a flue gas discharge system 2 connected to the furnace top and a combustion air supply system 3 connected to the tuyere. The exhaust gas discharge system 2 has a base end communicating with the furnace top of the cupola 1, a tip end communicating with a suction port of the exhaust blower 4, and has an auxiliary combustion furnace S in the middle thereof. The side communicates with the discharge port of the combustion air blower 5 and the tip side communicates with the tuyere of the cupola 1.

In the middle of the exhaust gas discharge system 2 and the combustion air supply system 3, a plurality of regenerative heat exchangers 6 are connected via first flow path switching means 7 and second flow path switching means 8, respectively. . This regenerative heat exchanger 6 may be of a single configuration.

The first flow path switching means 7 includes a regenerative heat exchanger 6
Opening / closing valve 7a for controlling the connection between the gas and the upstream pipe 2a of the exhaust gas discharge system 2, and the second opening / closing valve for controlling the connection between the regenerative heat exchanger 6 and the downstream pipe 3a of the combustion air supply system 3. 7b
By operating the first on-off valve 7a and the second on-off valve 7b, the flow path connected to the regenerative heat exchanger 6 is switched.

The second flow path switching means 8 includes a regenerative heat exchanger 6
Opening / closing valve 8a for controlling the connection between the heat exchanger 6 and the downstream pipe 2b of the exhaust gas discharge system 2, and the fourth opening / closing valve for controlling the connection between the regenerative heat exchanger 6 and the upstream pipe 3b of the combustion air supply system 3. 8b
The flow path connected to the regenerative heat exchanger 6 is switched by operating the third on-off valve 8a and the fourth on-off valve 8b.

Each regenerative heat exchanger 6 has a heat exchange chamber 9 forming an air passage for the exhaust gas discharge system 2 and the combustion air supply system 3, and receives and receives heat inside the heat exchange chamber 9. A plurality of heat storage elements 10 constituting a heat exchange element to be performed are settled. The heat storage element 10 includes a refractory (ceramic material),
Composed of metal, refractory and metal hybrid products, φ10mm ~ φ
50 mm spherical granules, 10 mm to 50 mm square prisms or hollow prisms, or honeycomb ceramics that are porous. Honeycomb ceramics have a cell pitch of 2.54 m.
m, and the partition wall thickness is about 0.43 mm. The shape of the heat storage element 10 is not limited to a spherical shape, a prismatic body, or the like, but may be any shape as long as the heat conductivity can be improved. Shape is conceivable.

The operation of the above configuration will be described below. Since the heat storage operation and the heat radiation operation in each heat storage type heat exchanger 6 are the same, the operation in one heat storage type heat exchanger 6 will be exemplarily described here.

During the heat storage operation, the first opening / closing valve 7a of the first flow path switching means 7 is opened, the second opening / closing valve 7b is closed, and the third opening / closing valve 8a of the second flow path switching means 8 is opened. The fourth on-off valve 8b is closed, the upstream pipe 2a of the exhaust gas discharge system 2 is connected to the heat exchange chamber 9 of the regenerative heat exchanger 6, and the downstream pipe 2b of the exhaust gas discharge system 2 is connected to the heat exchange chamber 9. Connecting.

In this state, high-temperature exhaust gas (about 980 ° C.) discharged from the furnace top of the cupola 1 flows into the heat exchange chamber 9 of the regenerative heat exchanger 6 through the upstream pipe 2 a of the exhaust gas discharge system 2, After circulating through the gap between the plurality of heat storage elements 10 forming the heat exchange element which is settled in the exchange chamber 9, the heat storage element 10 is heated to a temperature of about 200 ° C., and then the suction blow of the exhaust blower 4 is performed. The water is drawn by the pressure and flows out of the heat exchange chamber 9 into the downstream pipe 2 b of the exhaust gas discharge system 2. During this time, the heat storage element 10 of the heat storage heat exchanger 6
Can store high-temperature heat by receiving heat from exhaust gas in a high-temperature range, thereby improving temperature efficiency.

During the heat radiation operation, the first on-off valve 7a of the first flow path switching means 7 is closed and the second on-off valve 7b is opened, and the third on-off valve 8a of the second flow path switching means 8 is closed. The fourth on-off valve 8b is opened, the upstream pipe 3b of the combustion air supply system 3 is connected to the heat exchange chamber 9 of the regenerative heat exchanger 6, and the downstream pipe 3a of the combustion air supply system 3 is connected to the heat exchange chamber. 9 In this state, the combustion air (room temperature) supplied from the combustion air blower 5 is supplied to the combustion air supply system 3.
Flows into the heat exchange chamber 9 of the regenerative heat exchanger 6 through the upstream pipe 3b, and flows through the gaps between the plurality of heat storage elements 10 which are settled in the heat exchange chamber 9 to flow therethrough.
0 takes away the heat radiated and raises the temperature (about 750 ° C),
The heat flows from the heat exchange chamber 9 into the cupola 1 through the tuyere through the downstream pipe 3 a of the combustion air supply system 3.

As shown in FIG. 2, three of NO.1, NO.2 and NO.3
In each of the base regenerative heat exchangers 6, the repetitive heat storage operation and the heat release operation are performed differently. Now N
In the process in which the heat storage heat exchanger 6 of O.1 is performing the heat storage operation (heating), the heat storage heat exchanger 6 of NO.2 is in the latter half of the heat radiation operation (blowing), and the heat storage operation of NO.3 is performed. The heat exchanger 6 is in the first half of the heat radiation operation (blowing).

Therefore, while one heat storage type heat exchanger 6 is operated for heat storage, the other heat storage type heat exchanger 6 is operated to radiate heat, so that heat exchange between the exhaust gas and the combustion air via the heat storage element 10 is performed. Can be performed continuously,
Combustion air at a stable temperature (about 750 ° C.) can always be supplied to the tuyere of the cupola 1. Moreover, since the three regenerative heat exchangers 6 are operated with a phase difference of one-third of the entire process, the blast temperature accompanying the weakening of the amount of radiated heat in the latter half of the radiating operation (blowing) of the heat exchanger 6. Can be compensated for by the abundant heat release in the first half of the heat release operation (blowing) of the other heat storage type heat exchanger 6, and the temperature change of the combustion air can be reduced.

[0022]

As described above, according to the present invention, during the heat storage operation and the heat radiation operation, the heat storage element receives and radiates heat with the exhaust gas or the combustion air in a stationary state. Such wear of the circulation duct and wear of the heat storage element itself do not occur, and noise and vibration do not occur. Also, by connecting a plurality of regenerative heat exchangers in parallel to the exhaust gas discharge system and the combustion air supply system, and performing the heat storage operation and the heat radiation operation repeatedly performed in each heat storage heat exchanger differently In addition, the heat exchange between the exhaust gas and the combustion air through the heat storage element can be continuously performed, and the combustion air at a stable temperature can always be supplied to the tuyere of the industrial furnace.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a cupola waste heat utilization apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an operation cycle in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cupola 2 Exhaust gas discharge system 3 Combustion air supply system 4 Exhaust blower 5 Combustion air blower 6 Heat storage type heat exchanger 7 First flow switching means 8 Second flow switching means 9 Heat exchange chamber 10 Heat storage element

Claims (3)

[Claims] An exhaust gas discharge system having a base end communicating with a furnace top of an industrial furnace such as a cupola and a tip end communicating with a suction port of an exhaust blower, a base end communicating with a discharge port of a combustion air blower and a tip end communicating It has a combustion air supply system communicating with the tuyere of an industrial furnace, and a regenerative heat exchanger interposed in the exhaust gas discharge system and the combustion air supply system, and the regenerative heat exchanger internally receives heat. A heat exchange chamber in which a plurality of heat storage elements forming a heat exchange element for radiating heat are provided, and one connection of the heat exchange chamber is connected to an upstream pipe of an exhaust gas discharge system via a first flow path switching unit; The other connection of the heat exchange chamber is connected to the downstream pipe of the combustion air supply system via a second flow path switching means to the downstream pipe of the exhaust gas discharge system and the upstream pipe of the combustion air supply system. Discontinuation of industrial furnaces characterized by switchable communication Heat utilization equipment. 2. The industrial furnace waste heat utilization apparatus according to claim 1, wherein a plurality of regenerative heat exchangers are connected in parallel to the exhaust gas discharge system and the combustion air supply system. 3. The industrial device according to claim 1, wherein the heat storage element comprises a heat-resistant member such as a honeycomb ceramic having a porous body or a ceramic ball having a particle diameter of 10 to 50 mm. Furnace waste heat utilization equipment.