KR101032829B1 - control method for waste gas and heat exchanger by using heat recovery system of reheating furnace - Google Patents

Abstract

Heat recovery system of the heating furnace according to an embodiment of the present invention, the heat storage burner having a heat storage body is stored heat; A non-heat storage burner using heated combustion air; An exhaust gas passage through which exhaust gas generated by the heat storage burner and the non-heat storage burner is discharged; A heat exchanger installed in a flue line which is a main passage of the exhaust gas to recover heat of the exhaust gas; A second exhaust gas passage installed between the exhaust gas passage and the heat exchanger to enable exhaust gas discharge from the exhaust gas passage to the flue line; And an induction blower (ID fan) installed in the exhaust gas passage to transfer a part of the exhaust gas coming from the heat storage burner to a stack, and introducing another portion of the exhaust gas into the heat exchanger through the second exhaust gas passage. It is characterized in that the configuration.

In addition, the exhaust gas and heat exchanger management method using a heat recovery system of the heating furnace according to an embodiment of the present invention, the heat storage burner having a heat accumulator and the non-heat storage burner using the combustion air heated through the heat exchanger. In the flue gas and heat exchanger management method using the heat recovery system of the heating furnace configured to, the flue gas passage through which the flue gas generated by the heat storage burner and the non-heat storage burner is discharged, at the inlet side of the heat exchanger installed in the flue line. It is connected via an ID fan and a second exhaust gas passage, and the exhaust gas temperature at the inlet side of the heat exchanger is controlled to be within a heat exchanger deterioration temperature so that natural exhaust gas can be discharged in consideration of the increase amount of exhaust gas supplied from the heat storage burner. Characterized in that it comprises a step.

According to the present invention, in operation of a furnace using a regenerative burner and a conventional burner using combustion air heated by a heat exchanger at the same time, when the amount of exhaust gas discharged to a flue line increases, an induced blower ( By reducing the amount of exhaust gas discharged to the heat exchanger side through the ID fan), it is possible to prevent deterioration of the heat exchanger by lowering the temperature of the exhaust gas exiting the heat exchanger side, and an excessive amount of preheating air heat exchanged through the heat exchanger which is prevented from deterioration. It is possible to simply configure the device of the heating furnace by heating only the preheating air required, and to reduce the amount of exhaust gas discharged to the flue line to easily control the furnace pressure of the heating furnace, the heat exchange As the deterioration of the gas is prevented, it is necessary to protect the heat exchanger pipe of the heat exchanger by excessively increasing the amount of combustion air. Since there is no need, only the necessary combustion air can be heated, and it is unnecessary to discharge excessively heated combustion air.

Furnace, flue-gas, heat exchanger, burner, heat accumulator

Description

Control method for waste gas and heat exchanger by using heat recovery system of reheating furnace}

The present invention relates to a heat recovery system of a furnace and a method for managing flue gas and heat exchanger using the same, in particular in the process of releasing the flue gas generated after burning the fuel to heat the material in the reheating furnace, The present invention relates to a heat recovery system of a furnace for managing within a facility specification of a heat exchanger installed in accordance with a situation and installed for heat recovery, and to a method for managing exhaust gas and heat exchanger using the same.

In general, when heating a material in a reheating furnace, waste gas generated through a burner that burns fuel is discharged out of the heating furnace after heating the material in the furnace, and the amount of heat of the exhaust gas released. Accounted for the largest percentage of the heat lost in a furnace.

Table 1 shows an example of the passion acid for the heating furnace.

Passionate Measurement Results division Calories / ratio Supply calories


Fuel combustion heat
Sensible air for combustion
Scale generation column
Charging material heat 279.8
57.5
10.0
25.9 75.0
15.4
2.7
6.9 Consumed calories




Extract material sensible heat
Flue gas sensible heat
Scale sensible heat
Coolant sensible heat
Heat dissipation
Unknown loss fever 196.0
121.8
2.3
40.9
12.1
0.1 52.5
32.6
0.6
11.0
3.2
0.0 Sum 373.2 (kcal) 100.0 (%)

As shown in Table 1 above, the heat dissipation of the exhaust gas accounts for the second largest ratio after the heat generated by the heating material, and in this aspect, if the reduction of the exhaust gas calories or recovery of some of the exhaust gas calories is improved, the overall thermal efficiency is improved. As a result, a heat exchanger is usually provided as a heat exchanger for heat recovery of exhaust gas.

As a method of installing the heat exchanger, there are a method of installing in a flue line, which is a main passage of exhaust gas, and a method of installing as an accessory of a burner installed inside a furnace body. In the past, a metal heat exchanger was used. When using a heat exchanger of a metal material, the exhaust gas temperature is usually about 800 to 850 ° C., thus limiting the number of heat recovery. Therefore, in order to overcome this limitation of the heat recovery, ceramic-based regenerative heat exchangers have recently been used as an accessory for burners.

1 is a view showing an installation example of a conventional ceramic heat storage heat exchanger, and as shown therein, a burner having a ceramic heat storage heat exchanger is generally operated by using a set of two heat storage burners 10 and 20. Each of the heat storage burners 10 and 20 has a ceramic heat exchanger, and repeats the combustion operation and the exhaust gas suction operation at regular time intervals, and sucks the exhaust gas generated from the burners located opposite to the heat storage unit 12. After the heat is stored in the heat storage body (not shown) in the inside of the fan 22, the combustion air flows through the combustion air input lines 14 and 24 during the combustion operation.

As the heating temperature of the heat storage body heat exchanged as described above generally reaches about 70 to 80% of the heating temperature of the corresponding heating zone, although it is a relatively expensive burner, it is possible to perform more heat recovery than the conventional method. It is employ | adopted a lot in the heating furnace installed.

Table 2 illustrates the load situation takes groups existing heat exchanger in the case of separate administration of the exhaust gas, the heat exchanger makin is designed on the basis of the maximum operating conditions of conventional corresponding equipment, the table 2 when the amount of the maximum exhaust gas 37,000 Nm ³ / Hr and exhaust gas temperature are 830 degreeC conditions.

division Design Max Exhaust gas volume (Nm ³ / Hr) 26,700 37,000 REC entrance temperature (℃) 830 830 REC exit temperature (℃) 630 621 Flue gas pressure drop (mm H ₂ 0) 10 20 Preheating air volume (Nm ³ / Hr) 9,300 14,200 REC inlet air temperature (℃) 20 20 REC exit air temperature (℃) 670 630 Preheating air pressure drop (mm H ₂ 0) 100 185

If the exhaust gas exceeds the maximum exhaust gas value given in Table 2, the pressure loss generated in the heat exchanger increases, and if the exhaust gas temperature exceeds the reference temperature, the heat exchanger heat pipes deteriorate with the increase in the pressure loss. There is a possibility.

Eventually, the design of the heat exchanger is made in the case of the maximum condition of the corresponding equipment in case of the case, and if the burner installed in the corresponding furnace has a heat storage burner having its own heat accumulator and the combustion for heating by the heat exchanger When using non-heat storage (conventional) burners that use air at the same time, it becomes a bit difficult to meet design criteria.

In the case of regenerative burners, some of the generated flue-gas is self-inhaled and some are discharged through the flue line, while in the case of non-regenerative burners, they are discharged through the flue line as before. The heat exchanger is designed by calculating the amount of exhaust gas discharged through the flue line according to the type and capacity of the burner, but the intake rate of exhaust gas sucked from the heat storage burner depends on the operating conditions or clogging of the burner. Due to deterioration of performance, there is a case that operation by a certain ratio cannot always be performed.

An example of such a case is shown in Table 3 below. That is, Table 3 shows the load situation applied to the existing heat exchanger in the case of integrated management of each exhaust gas according to the operation situation, and corresponds to the case of discharging the exhaust gas under the same conditions as in Table 2, the heat storage burner, It is assuming that the normal operating condition (80% intake rate of exhaust gas after combustion of regenerative burner, 0% in case of non-regenerative burner) is assumed in a heating furnace composed of non-regenerative burners.

division Design Max Case 1 Case 2 Case 3 Exhaust gas volume (Nm ³ / Hr) 26,700 37,000 49,054 60,142 90,275 REC entrance temperature (℃) 830 830 820 994 762 REC exit temperature (℃) 630 621 656 828 668 Flue gas pressure drop (mm H ₂ 0) 10 20 36 64 17 Preheating air volume (Nm ³ / Hr) 9,300 14,200 14,200 14,200 18,000 REC inlet air temperature (℃) 20 20 20 20 20 REC exit air temperature (℃) 670 630 650 820 570 Preheating air pressure drop (mm H ₂ 0) 100 185 193 224 328

When the exhaust gas intake rate after combustion by the heat storage burner is reduced due to the burner's deterioration in the heating furnace of this configuration, the amount of exhaust gas discharged to the flue line is increased, which causes problems in the heat exchanger installed for the non-heat storage burner. Will be generated.

Case 1 and Case 2 shown in Table 3 are such cases. Case 1 shows a case where the exhaust gas suction rate of the heat storage burner is 70% level, and Case 2 shows a case where the exhaust gas suction rate is reduced to 50% level. As a result, the flue gas pressure and temperature increase cause deterioration of the heat exchanger and the lack of drafting ability to discharge the flue gas.

Of course, considering the change rate of the flue gas intake rate in consideration of this point, the corresponding flue line and the heat exchanger can be designed, but in the end, the overdesign for the case is made, resulting in inefficient overdesign and the corresponding equipment cost. This will cause an increase in price and a decrease in operating efficiency.

In addition, in the case of the combustion air heated in the heat exchanger, since the place of use is only for the non-heat storage burner, the usage amount of the heated combustion air must be limited, so the amount of combustion air heated in the heat exchanger must be controlled. In other words, if the amount of combustion air is increased to prevent deterioration of the heat exchanger, the amount of combustion air heated more than necessary will not be used in the end and should be discharged outside to prevent deterioration of the heat exchanger. There is a need for an air discharge line for combustion.

Of course, in order to avoid this situation, it is necessary to increase the amount of dilution of the exhaust gas to lower the temperature of the exhaust gas, but this leads to an increase in another equipment cost and also causes an excessive design due to the increase of the overall exhaust gas amount. In consideration of these points, in some cases, even a heating furnace configured by mixing a regenerative burner and a non-regenerative burner is completely designed and used without a heat exchanger. However, in the case of a non-regenerative burner, the air in the atmosphere without preheating combustion air is used. The overall heating caused by using causes a problem of lowering the thermal efficiency.

In the case of the appropriate capacity design of the heat exchanger for the heat recovery of the exhaust gas, which is installed in the flue line when the burner having the heat accumulator and the conventional burner without the heat accumulator are installed at the same time in the furnace. Since the difference is large depending on the operating conditions, capacity design is not easy.

In particular, when the exhaust gas generated by the operation of the burner with the heat storage body is not smoothly discharged through the flue line, it is not easy to control the furnace pressure due to the increase of the exhaust gas amount, and the exhaust gas temperature is high. Due to the deterioration of the heat exchanger and the amount of preheating air made with the heat exchange is excessive, there is a problem that the apparatus of the heating furnace is complicated, the reference numeral 16, 26 in Fig. 1 is the exhaust gas outlet line.

The present invention has been made in view of the problems of the prior art as described above, an object of the present invention is to use a non-regenerative type (conventional) burner using a regenerative type burner and the combustion air heated through the heat exchanger at the same time. When operating the furnace, if the amount of exhaust gas discharged to the flue line increases, it reduces the amount of exhaust gas emitted to the heat exchanger side through the ID fan, thereby lowering the temperature of the exhaust gas exiting the heat exchanger side. The present invention provides a heat recovery system of a heating furnace that can prevent deterioration of the furnace and a method for managing exhaust gas and heat exchanger using the same.

Another object of the present invention is to prevent excessive deterioration of the amount of preheating air heat exchanged through a heat exchanger that prevents deterioration, so that only the necessary preheating air is heated, and a heat recovery system of a furnace capable of simply configuring the apparatus of the furnace and exhaust gas using the same And a heat exchanger management method.

Still another object of the present invention is to provide a heat recovery system of a heating furnace capable of easily controlling the furnace pressure by reducing the amount of exhaust gas discharged to a flue line and a method of managing the exhaust gas and heat exchanger using the same. .

Another object of the present invention is to increase the amount of combustion air excessively to prevent deterioration of the heat exchanger, so that it is not necessary to protect the heat transfer pipe of the heat exchanger, so that only necessary combustion air can be heated, and the excessively heated combustion air It is to provide a heat recovery system of a furnace that does not require the emission of exhaust gas and a method of managing flue gas and heat exchanger using the same.

The objects of the present invention are not limited to the above-mentioned objects, and other objects which are not mentioned will be clearly understood by those skilled in the art from the following description.

An object of the present invention described above is a heat storage burner having a heat storage body in which heat is stored; A non-heat storage burner using heated combustion air; An exhaust gas passage through which exhaust gas generated by the heat storage burner and the non-heat storage burner is discharged; A heat exchanger installed in a flue line which is a main passage of the exhaust gas to recover heat of the exhaust gas; A second exhaust gas passage installed between the exhaust gas passage and the heat exchanger to enable exhaust gas discharge from the exhaust gas passage to the flue line; And an induction blower (ID fan) installed in the exhaust gas passage to transfer a part of the exhaust gas coming from the heat storage burner to a stack, and introducing another portion of the exhaust gas into the heat exchanger through the second exhaust gas passage. It is achieved by a heat recovery system of the heating furnace constituted.

In the present invention, the amount of exhaust gas supplied from the heat storage burner to the flue line is controlled by a control valve installed at an inlet of the ID fan.

On the other hand, the object of the present invention described above is a flue gas passage in which flue gas generated by a heat storage burner having a heat storage body and a non-heat storage burner using combustion air heated by a heat exchanger is discharged to a flue line. Connected to the inlet side of the installed heat exchanger via an ID fan and a second exhaust gas passage,

The exhaust gas and heat exchanger using the heat recovery system of the heating furnace comprising the step of controlling the temperature of the exhaust gas at the heat exchanger inlet temperature within the generation temperature of the heat exchanger to allow the natural discharge of the exhaust gas in consideration of the increase in the exhaust gas supplied from the heat storage burner. It is achieved by management method.

In the present invention, in the exhaust gas temperature control step, when the exhaust gas discharge amount to the flue line increases, a part of the discharged exhaust gas is discharged to the stack through the induction blower to discharge the temperature of the exhaust gas to the heat exchanger. It is characterized in that to lower the heat exchanger to lower the temperature.

In addition, in the present invention, the amount of exhaust gas supplied from the heat storage burner to the flue line is controlled by a control valve installed at the inlet of the ID fan.

According to the heat recovery system of the heating furnace and the exhaust gas and heat exchanger management method using the same according to the present invention as described above has the following effects.

First, when the exhaust gas emission to the flue line increases during the operation of a furnace using a regenerative burner and a conventional burner using combustion air heated by a heat exchanger, an ID fan is used. By reducing the amount of exhaust gas discharged to the heat exchanger side through the lower the temperature of the exhaust gas to the heat exchanger side it is possible to prevent the deterioration of the heat exchanger.

Second, since it is possible to prevent an excessive amount of preheating air in which heat exchange is performed through a heat exchanger that is prevented from deterioration, a device of the heating furnace can be simply configured by heating only necessary preheating air.

Third, it is possible to easily control the furnace pressure of the furnace by reducing the amount of exhaust gas discharged to the flue line.

Fourth, since the deterioration of the heat exchanger is prevented, it is not necessary to protect the heat transfer pipe of the heat exchanger by excessively increasing the amount of combustion air, so that only the necessary combustion air can be heated, and it is not necessary to discharge the overheated combustion air. Do.

The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred configuration and effect of the present invention.

MEANS TO SOLVE THE PROBLEM The present inventor accommodates the generation | occurrence | production of the exhaust gas suction rate down due to the change of operating conditions and the deterioration of the heat storage burner for the heating furnace comprised by mixing a heat storage burner and a non-heat storage (conventional type) burner, and the excess heating amount of the combustion air The way to avoid the release of was found.

FIG. 2 is a schematic view for explaining a heat recovery system of a heating furnace and a method for managing exhaust gas and heat exchanger using the same according to an embodiment of the present invention, referring to the respective burners (regenerative, non-regenerative, not shown). Exhaust gas passage 34a through which the generated flue gas exits is the same as before, but exhaust gas passage 34a and flue gas are discharged from exhaust gas passage 34a of the heat storage burner to flue line 32. Flue) The second exhaust gas passage 34b is newly installed between the heat exchangers 30 installed in the line 32, and the heat exchanger 30 is designed in consideration of the amount of exhaust gas coming from the heat storage burner.

In addition, the amount of exhaust gas flowing from the heat storage burner to the flue line 32 via the second exhaust gas passage 34b is an induced draft fan (ID Fan) installed in the exhaust gas passage 34a. It can be adjusted by the control valve 36 provided at the inlet side, which is increased or decreased as necessary by a thermometer (not shown) installed at the inlet side of the heat exchanger 30.

On the other hand, a part of the exhaust gas flowing into the side of the induced blower 38 is a stack (40), the other part is introduced into the heat exchanger 30 through the second exhaust gas passage 34b (Fig. 2). Arrow).

In the case of operating the furnace with such a structure, when the exhaust gas discharge amount to the flue line 32 is increased due to the deterioration of the exhaust gas suction rate performance of the heat storage burner, a part of the exhaust gas discharged is transferred to the induction blower 36. It is possible to prevent the high temperature of the heat exchanger (30) by lowering the temperature of the exhaust gas exiting the stack (40) through the heat exchanger (30) side through the).

At this time, the exhaust gas entrance temperature of the heat exchanger 30 as a reference is a temperature at which deterioration of the heat exchanger does not occur. Thus, when the temperature of the exhaust gas introduced into the heat exchanger 30 is managed, deterioration of the heat exchanger 30 is achieved. In order to prevent excessively increasing the amount of combustion air, it is not necessary to protect the heat transfer pipe of the heat exchanger 30, so that only the necessary combustion air may be heated, and there is no need to release the excessively heated combustion air. .

The results of applying this concept to the actual situation are shown in Case 3 of Table 3 above. Case 3 of Table 3 is an example of applying the present invention to the aforementioned Table 3, by sending a part of the exhaust gas discharged through the heat storage burner to the flue line (32) side to determine the entrance temperature of the heat exchanger (30) To reduce the increase in pressure loss due to the increased amount of exhaust gas, and increase the corresponding cross-sectional area of the flue line 32 in which the heat exchanger 30 is installed, and also by adjusting the heat pipe spacing of the heat exchanger. Deterioration of the machine 30 and the difficulty of the pressure control can be eliminated, and reference numeral 32a in FIG. 2 denotes a damper.

As described above, the heat recovery system of the furnace according to the present invention and the exhaust gas and heat exchanger management method using the same have been described with reference to the illustrated drawings, but the present invention is not limited by the embodiments and drawings disclosed herein, Of course, various modifications may be made by those skilled in the art within the scope of the technical idea.

1 is a view showing an installation example of a heat storage type heat exchanger of a conventional ceramic series,

Figure 2 is a schematic diagram for explaining a heat recovery system of the heating furnace according to an embodiment of the present invention and the exhaust gas and heat exchanger management method using the same.

Description of the Related Art

10,20: heat storage burner 12,22: heat storage

30: heat exchanger 32: flue line

34a: flue gas passage 34b: second flue gas passage

36: control valve 38: manned blower (ID Fan)

40: stack

Claims (5)

delete delete An induction blower at the inlet side of the heat exchanger installed in a flue line is provided with a heat storage burner having a heat storage body and an exhaust gas passage through which exhaust gas generated by a non-heat storage burner using combustion air heated by a heat exchanger is discharged. Through the ID Fan and the second exhaust gas passage, The exhaust gas and heat exchanger using the heat recovery system of the heating furnace comprising the step of controlling the temperature of the exhaust gas at the heat exchanger inlet temperature within the generation temperature of the heat exchanger to allow the natural discharge of the exhaust gas in consideration of the increase in the exhaust gas supplied from the heat storage burner. How to manage. The method of claim 3, wherein In the exhaust gas temperature control step, When the amount of exhaust gas discharged to the flue line is increased, a portion of the discharged gas is discharged to the stack through the draw fan to lower the temperature of the exhaust gas exiting the heat exchanger to prevent the heat exchanger from becoming hot. A method for managing exhaust gas and heat exchanger using a heat recovery system of a furnace. The method according to claim 3 or 4, The amount of exhaust gas supplied from the heat storage burner to the flue line is The exhaust gas and heat exchanger management method using a heat recovery system of the heating furnace, characterized in that it is controlled by a control valve installed at the inlet fan (ID Fan).

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