JPS6261086B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust heat recovery device for a heating furnace having multiple zones for heating both cold and hot pieces of material.

Figures 1 and 2 show an example of a conventional device, and when heating cold pieces during normal operation, all of the preheating zone b, heating zone c, and soaking zone d of the heating furnace a are burned. , the exhaust gas is dispersed and passed through a set of heat exchangers e, f, and g arranged in parallel, and when heating the hot pieces, the combustion in the preheating zone b is stopped and the heating zone c is and burns only in the soaking zone d.

However, when heating the hot piece, the amount of exhaust gas decreases significantly compared to the amount of exhaust gas when heating the cold piece, which burns all zones b, c, and d.
The amount of exhaust gas distributed in f and g is drastically reduced, and the temperature of the exhaust gas is also lowered, resulting in a decrease in heat exchange efficiency, which poses the problem of requiring a large heat exchange device.

In addition, in the conventional device, combustion air from a cold air pipe h is guided to each heat exchanger e, f, g, and air preheated by heat exchange is sent to the heating furnace through a single preheated air pipe i. Since the preheated air was guided to zone a and then supplied to each zone b, c, and d via a branch pipe, a device for adjusting the amount of preheated air supplied to each zone b, c, and d was installed at the branch pipe position. This poses problems such as the need to provide heat-resistant valves and the like because the temperature of the device increases.

The present invention has been made to solve the above-mentioned conventional problems, and includes a plurality of channels for separating and guiding the exhaust gas from a heating furnace equipped with a plurality of zones, and a heat exchanger installed in each of the channels. At the same time, a suitable number of the flow paths are provided with seal dampers capable of blocking the flow paths, and each of the heat exchangers and each of the zones are connected through dedicated preheated air pipes so as to correspond to each other. This relates to an exhaust heat recovery device for a heating furnace.

Embodiments of the present invention will be described below with reference to the drawings.

Figure 3 shows an example of the present invention.
a, heating furnace 1 equipped with a heating zone 1b and a soaking zone 1c;
The exhaust gas from the heat exchanger 2 is guided to the heat exchanger 2. Inside the heat exchange device 2, three exhaust gas flow paths are provided by separation walls 3 corresponding to the number of zones of the heating furnace 1.
heat exchangers 5a, 5b, 5c in each flow path 4a, 4b, 4c.
Place.

Each of the heat exchangers 5a, 5b, 5c has its own cold air pipe 6a, 6b, 6c and preheated air pipe 7a,
7b and 7c are connected to form one heat exchanger and heating furnace 1.
The preheated air pipes 7a, 7b, and 7c are connected so that the preheated air pipes 7a, 7b, and 7c correspond to each other. Furthermore, the flow path 4
Seal dampers 8 are provided at appropriate numbers of a, 4b, and 4c to block the flow of exhaust gas in the flow paths. In the illustrated case, it is provided in the flow path 4a. Further, a fifth pipe is provided in the cold air pipe 6a of the heat exchanger 5a provided in the flow path 4a provided with the seal damper 8.
A cold air damper 9 is provided as shown in the figure. 1 in the diagram
0 is a furnace pressure control damper provided in the exhaust gas duct 11.

FIG. 6 shows an example of a system for controlling the amount of preheated air supplied to each zone 1a, 1b, 1c of the heating furnace 1. (only shown)
A preheated air amount control valve 12 is provided in the preheated air amount control valve 12. A fuel control valve 1 adjusted by a temperature control device 13 that controls the temperature of a preheating zone 1a of a heating furnace 1.
4 is provided in the fuel pipe 15, and the amount of preheated air is adjusted via a control device 16 that controls the supply ratio of preheated air to the amount of fuel supplied through the fuel pipe 15. 17 is provided, and the air amount control device 17 is connected to the preheating air amount control valve 12. 18 is an orifice, and 19 is an arithmetic unit.

Next, the effect will be explained.

When performing normal cold piece heating, burners in all zones 1a, 1b, and 1c are fired with the seal damper 8 and cold air tamper 9 fully open, and all heat exchangers 5a, 5b, and 5c are fired. Preheat the air. At this time, the cold air pipes 6a, 6b,
Preheating air amount control valve 1 provided in each of 6c
2, the amount of preheated air supplied to each zone 1a, 1b, 1c is individually adjusted.

Further, when hot-piece heating is performed, the seal damper 8 is fully closed to block the flow path 4a since burner combustion in the preheating zone 1a is not performed. As a result, heating zone 1b
And the exhaust gas from the soaking zone 1c is transferred to heat exchangers 5b, 5
It passes through channels 4b and 4c equipped with c. Therefore, in either case of cold piece heating or hot piece heating, the amount of exhaust gas passing through the flow paths 4b, 4c does not change much, and the performance of the heat exchange device 2 can be stabilized. Therefore, efficient heat exchange can be performed at the same exhaust gas temperature, and the heat exchange device 2 can be downsized. It is also considered that when the seal damper 8 is fully closed, the cold air damper 9 is slightly opened to supply cold air so that the inside of the flow path 4a does not become high temperature due to the exhaust gas leaking from the seal damper 8. Further, when the combustion amount of the entire heating furnace 1 or the combustion amount of a specific zone becomes less than a set value, the seal damper 8 is closed to shut off the flow path, thereby cutting off the supply of preheated air to the zone. It can also be activated automatically.

It should be noted that the present invention is not limited only to the above-mentioned embodiments, and various changes may be made without departing from the gist of the present invention.

According to the above-described exhaust heat recovery device for a heating furnace of the present invention, various excellent effects can be achieved as described below.

(i) By installing a seal damper in the flow path equipped with a heat exchanger, when combustion is stopped in a zone of the heating furnace, it is possible to block the flow of exhaust gas in the flow path corresponding to that zone. Therefore, the flow rate of the exhaust gas in the other channels can be kept constant, and efficient and stable heat exchange can be performed.

(ii) By performing efficient heat exchange, it is possible to downsize the heat exchange device.

(iii) The amount and temperature of preheated air can be stabilized.

(iv) Since each heat exchanger and each zone are exclusively connected by their own preheating piping, it is possible to install a cold air pipe in each heat exchanger and control the amount of air in the cold air pipe. If a device is provided for this purpose, the device can be easily implemented without considering the influence of temperature, and a heat-resistant control valve is not required.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a conventional device, FIG. 2 is a view taken along the - arrow in FIG. 1, FIG. 3 is an explanatory diagram showing an embodiment of the present invention, and FIG. A sectional view, FIG. 5 is an explanatory diagram of a cold air pipe portion, and FIG. 6 is an explanatory diagram showing an example of a method for controlling the amount of preheated air. 1 is a heating furnace, 1a is a preheating zone, 1b is a heating zone, 1
c is a soaking zone, 2 is a heat exchange device, 4a, 4b, 4c
is a flow path, 5a, 5b, 5c are heat exchangers, 6a, 6
b and 6c are cold air pipes, 7a, 7b, and 7c are preheated air pipes, 8 is a seal damper, 9 is a cold air damper, and 12 is a preheated air amount control valve.

Claims (1)

[Claims] 1. A plurality of channels are provided to separate and guide exhaust gas from a heating furnace having a plurality of zones, a heat exchanger is provided in each of the channels, and an appropriate number of the channels can be blocked. 1. An exhaust heat recovery device for a heating furnace, characterized in that a seal damper is provided, and each of the heat exchangers and each of the zones are connected through dedicated preheated air pipes so as to correspond to each other.