KR20100073732A - Rotary regenerator type heat exchanger for waste hert recovery in reheating furnace - Google Patents

Abstract

PURPOSE: A heat exchange system for a waste heat recovery in a reheating furnace is provided to reduce the generation amount of NOx and to protect a suction fan by partially mixing burning air and waste gas in a regenerative heat exchange. CONSTITUTION: A heat exchange system for a waste heat recovery in a reheating furnace comprises: a blower which supplies air for burning; a burning air supply line(25) which supplies the burning air supplied from the blower to a burner; a waste gas exhaust line(20) which exhausts waste gas of high temperature created in a reheating furnace; and a regenerative heat exchanger(33) which is connected to the burning air supply line and the waste gas exhaust line and includes a honeycomb regenerative heat reservoir(34) which is composed of ceramic material and proceeds direct heat exchange, separating plates(40) which form sections by dividing the regenerative heat reservoir to the radial direction from the center of a circle, and a rotary shaft(36) which is formed at the center of the heat exchanger.

Description

Rotary regenerator type heat exchanger for waste hert recovery in reheating furnace

The present invention relates to a heat recovery system for heat recovery of a heating furnace which improves the heat recovery rate and reduces maintenance time when recovering the heat exhaust gas exhaust gas discharged from the heating furnace.

A heating furnace is a facility which usually burns fuel by a burner and heats up and heats a to-be-heated object, and is an energy-saving facility which is generally maintained at 1200 degreeC or more high temperature. Therefore, it has been recognized that it is very important to improve the thermal efficiency of the furnace to lower the fuel unit, and for this purpose, various heat recovery devices have been developed and used.

It is well known that the largest part of the waste heat discharged from the furnace is the arrangement of combustion flue gas, and as a method for recovering the combustion flue gas, a heat exchanger for preheating combustion air is generally installed. It is operating.

1 is a block diagram showing a conventional heating furnace and a heat recovery system for heat recovery. In the conventional heating furnace 1, the material 2 in the heating furnace 1 is burned in a charging zone, a preheating zone, a heating zone, and a cracking zone. After heating, the combustion flue gas of about 950 ° C. is sent to the heat exchanger 10 through the flue 6. At this time, the heat exchanger is made of metal, and the dilution fan 8 is installed in the flue so that the temperature of the combustion flue gas does not exceed a maximum of 850 ° C due to the constraint of the material.

In addition, when the temperature of the combustion flue gas measured by the thermocouple 9 exceeds a predetermined value, the dilution fan 8 is operated by the distributed control system (hereinafter, referred to as 'DCS') 12 to produce a flue (6). The temperature of the combustion flue gas passing through) is mixed with the outside air at room temperature to maintain an appropriate temperature of the flue gas and send it to the heat exchanger 10.

However, in the case of the above method, since the heat recovery rate of the heat exchanger is less than 70%, it is difficult to preheat the temperature of the combustion air to 600 ° C. or higher, which causes a problem in maximizing the sensible heat recovery. In addition, in terms of material of heat exchanger, it is difficult to maintain the outlet temperature of heating furnace above 850 ℃ for protection of heat pipe, so the temperature of preheating zone, which is the outlet of heating furnace, cannot be managed high. There is a problem of lengthening. In addition, in the case of the above-described method, as an indirect heat exchange method, there is a limit in improving the heat exchange rate due to the limitation of the heat exchange heat transfer area in the space given by the problem of the installation space, and there is a problem in that it takes a long time for maintenance and repair.

In order to solve the above problem, as shown in FIG. 2, alternating combustion regenerative combustion methods have been proposed in US Pat. Nos. 4,604,051 and 4,878,480. However, the above method is capable of recovering heat up to 90% by overcoming the conventional upper limit of heat recovery, but since two burners are operated in one set, a switching valve 9 must be installed for each group of burners, especially a large number of burners. Large furnaces used have the disadvantage that a large number of changeovers 9 and control devices must be installed in the combustion operation of the burners. Therefore, when a large-capacity burner is used, there is a big problem in low pressure and stability.

It is an object of the present invention to improve the heat exchange rate and recovery rate due to the discharge of combustion flue gas in a furnace.

The present invention provides a blower for supplying combustion air, a combustion air supply line for supplying combustion air supplied from the blower to a burner, a high temperature exhaust gas exhaust line generated in a heating furnace, and the combustion air supply. A heat exchange system for recovering an array of hot combustion flue gases generated in a heating furnace including a heat storage heat exchanger connected to a line and an exhaust gas exhaust line, wherein the heat storage heat exchanger is made of a ceramic material having a circular cross section and is capable of direct heat exchange. And a honeycomb heat accumulator layer formed therein, a plurality of separator plates separating the heat accumulator layer in the circumferential direction from the center to form a plurality of sections, and a rotation shaft formed at the center thereof. Provided is a heat exchange system for recovery.

In addition, the rotary shaft of the heat storage heat exchanger of the present invention provides a heat exchange system for heat recovery of the heating furnace, characterized in that the protective tube is formed on the outer peripheral surface.

In addition, a damper for adjusting the flow rate is provided on the exhaust gas exhaust line of the present invention, and a distributed control system (DCS) for adjusting the opening amount of the damper is provided. .

In another aspect, the present invention provides a heat exchange system for the heat recovery of the furnace, characterized in that the detection sensor for transmitting a low-pressure measurement signal in the furnace to the distributed control system further comprises.

In addition, the present invention is formed between the exhaust gas outlet of the furnace and the flue by-pass exhaust line for the exhaust of the combustion exhaust gas, on the bypass exhaust line further comprises a damper for adjusting the flow rate by the control of the DCS Provided is a heat exchange system for recovering heat from a furnace.

In addition, the regenerative heat exchanger of the present invention is a mixture of the combustion air and exhaust gas therein by the rotation of the heat accumulator is supplied to the burner of the heating furnace through the combustion air supply line or through the exhaust gas exhaust line It provides a heat exchange system for the heat recovery of the heating furnace characterized in that the discharge through the suction fan to the stack.

The present invention can improve the heat exchange rate and recovery rate due to the discharge of the combustion flue gas in the furnace to save energy, reduce the time required for maintenance, repair, and by mixing some of the combustion air and flue gas in the heat storage heat exchanger It reduces the amount of NOx and protects the suction fan.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Figure 3 is a block diagram showing a heat recovery heat exchange system according to the present invention.

The heat storage heat exchanger of the present invention is made of a ceramic material having a circular cross section, and has a honeycomb heat storage body formed therein, and a plurality of separation plates for separating the heat storage body from the center of the circumferential direction to form a plurality of sections, and at the center thereof. It provides a heat exchange system for recovering the arrangement of the heating furnace, characterized in that consisting of a rotating shaft formed.

In the material aspect of the conventional heat exchanger, the temperature of the exhaust gas was not exceeded 850 ° C. through the dilution fan, and because it was an indirect heat exchange method, there was a problem in improving the heat exchange rate due to the problem of the installation space and the limitation of the heat transfer area. In the material, the material is ceramic and the heat exchange method that can be directly heat exchanged is selected (Regenerator), and it is composed of the rotating type that can simultaneously heat storage and heat dissipation, and can overcome the problems of the installation space and the heat transfer area, thereby greatly improving the thermal efficiency. have. The ceramic material may be a material such as alumina or cordillite.

The heat accumulator layer 34, which is a heat exchange medium inside the heat exchanger 33, uses a honeycomb type, and the honeycomb has a very high heat transfer area and a high heat exchange rate as compared to the conventional metal heat exchanger.

A plurality of separator plates 40 are formed to separate the heat accumulator layer 34 in the circumferential direction from the center to form a plurality of sections. The honeycomb heat accumulator layer 34 is divided into a plurality of sections by the separator plate 40. It is divided into Therefore, it is easy to replace, maintain, and repair, minimize thermal shock, and vary the appropriate material and cell per square inch (CPSI) for each temperature range.

At the center of the heat exchanger 33, a rotating shaft 36 is formed to be rotatable. A protective tube 39 is formed on an outer circumferential surface of the rotary shaft, and the protective tube serves to cool with cold water to protect the rotary shaft of the heat exchanger from high temperature heat. On the other hand, the heat exchanger is arranged vertically to prevent the rotating shaft 36 from bending due to thermal stress and to remove non-uniform flow.

On the exhaust gas exhaust line 20 of the present invention, a damper 28 for adjusting the flow rate is installed, and a distribution control system (DCS) for adjusting the opening amount of the damper 28 is installed. A recovery heat exchange system is included. The damper 28 is installed between the outlet 42 of the exhaust gas of the heating furnace and the exhaust gas inlet 30 of the front end of the heat exchanger, and adjusts the flow rate of the hot exhaust gas discharged from the outlet 42 of the exhaust gas of the heating furnace. do.

In addition, the opening amount of the damper is compared to the set value (typically 1.0 mmH ₂ O) by the distributed control system DCS receiving the measurement signal of the low pressure detection sensor 23 of the heating furnace installed to control the flow rate of the exhaust gas. To control.

Meanwhile, in the present invention, a bypass exhaust line 43 for exhausting combustion exhaust gas is formed between the exhaust gas outlet 42 and the stack 38 of the heating furnace, and a damper for flow rate control is formed on the bypass exhaust line. 41) is further included, the heat recovery system for the heat recovery of the heating furnace is characterized in that it is configured, in the case of performing a sudden failure of the heat exchanger or the replacement, repair, cleaning, etc. of the heat accumulator therein the distributed control system When the (DCS) 26 adjusts the opening degree of the damper 41 formed on the bypass exhaust line 43, the combustion exhaust gas is discharged through the stack 38 by natural ventilation.

The regenerative heat exchanger 33 of the present invention is a mixture of the combustion air and exhaust gas therein is supplied to the burner of the heating furnace through the combustion air supply line or the stack through the suction fan through the exhaust gas exhaust line And a heat exchange system for recovering the heat of the furnace, characterized in that it is discharged.

The combustion flue gas of the furnace and the combustion air supplied from the blower are partially mixed while passing through the inside of the heat exchanger. That is, the exhaust gas flowing into the high temperature exhaust gas inlet 30 is not discharged to the low temperature exhaust gas outlet 32 in the same amount as the amount introduced into the heat exchanger, but is partially mixed with the combustion air due to the rotation of the heat accumulator inside the heat exchanger. Since it is supplied to the burner in the furnace through the air supply line for combustion, the maximum flame temperature of the burner is lowered, the oxygen concentration in the combustion zone is also reduced, thereby reducing the amount of NOx generated.

On the other hand, the combustion air flowing into the air inlet 31 at room temperature does not pass through the preheating air outlet, but rather is mixed with the exhaust gas due to the rotation of the heat accumulator inside the heat exchanger so that the temperature of the exhaust gas is reduced, so that the suction fan Can be protected from heat.

Hereinafter, the operation of the present invention will be described in more detail with reference to the accompanying drawings.

As shown in FIG. 3, the heating furnace 21 burns a plurality of ordinary burners 22 to extract the charged material by heating about 1200 ° C. In this process, the hot exhaust gas generated inside the furnace 21 is collected and discharged to the outlet of the furnace. The discharged high-temperature exhaust gas of 800 ~ 900 ℃ is introduced into the rotary heat storage heat exchanger 33 through the high temperature exhaust gas inlet 30 through the damper (28). The introduced high temperature exhaust gas is radiated while passing through the heat accumulator layer 34 and then exhausted through the chimney 38 at a low temperature of about 300 ° C. or less through the low temperature exhaust gas outlet 32.

The combustion air supplied through the blower fan 35 enters the rotary heat storage heat exchanger 33 through the air inlet 31 at room temperature, and passes through the heat storage layer 34 that is stored by the high temperature exhaust gas. It is preheated by the above-mentioned high temperature combustion air, and is supplied to the air nozzle of the normal burner 22 of a heating furnace via the preheating air outlet 29 via the combustion air supply line 25. As described above, the combustion exhaust gas of the furnace and the combustion air supplied from the blower are partially mixed while passing through the inside of the heat exchanger so that the maximum flame temperature of the burner is lowered and the oxygen concentration in the combustion zone is also reduced, thereby reducing the amount of NOx generated. It is effective, and the temperature of the exhaust gas is reduced, so that the suction fan can be protected from heat.

On the other hand, in order to control the low pressure according to the combustion capacity, the DCS 26 receives the measurement signal of the low pressure detection sensor 23 compared with the set value (normally 1.0mmH2O) to control the flow rate and the low pressure. It is possible to control the flow rate and the low pressure by adjusting the opening amount of the damper 28 formed on the exhaust line, that is, between the outlet of the heating furnace and the hot exhaust gas inlet 30 at the front end of the rotary heat storage heat exchanger 33. Made it possible. In addition, in case of sudden failure of the rotary heat storage heat exchanger 33 or replacement, repair, and cleaning of the internal heat storage layer 34, when the DCS 26 adjusts the opening degree of the damper 41, the exhaust gas is discharged to natural ventilation. It is exhausted to the stack 38 by this.

1 is a block diagram showing a conventional heat exchanger and heat recovery system for heat recovery.

2 is a block diagram of an alternating combustion type regenerative combustion method;

Figure 3 is a block diagram showing a heat recovery heat exchange system according to the present invention.

Explanation of the main symbols in the drawings

1. heating furnace 2. material

3. Normal burner 4. Dead wall

5. Regenerative burner 6. Year

7. Beam 8. Dilution Pan

9. Thermocouple 10. Heat exchanger

11. Stack

100. Blower 110. Damper

120. Switching valve 130. Heat storage chamber

140. Burner 1 150. Burner 2

160. Flame 170. Fuel supply control valve

20. Exhaust gas exhaust line 21. Furnace

22. Normal burner 23. Low pressure sensor

24. Fuel supply line 25. Combustion air supply line

DCS 27. Motor

28. Damper 29. Preheating air outlet

30. Hot exhaust gas inlet 31. Air inlet at room temperature

32. Low temperature exhaust gas outlet 33. Rotary regenerative heat exchanger

34. Heat storage layer 35. Blowing fan

36. Rotating shaft 37. Suction fan

38. Stacking 39. Sheriff

40. Separator 41. Damper

42. Exhaust gas outlet of furnace 43. Bypass exhaust line

Claims (6)

A blower for supplying combustion air, a combustion air supply line for supplying combustion air supplied from the blower to a burner, an exhaust gas exhaust line for exhausting high temperature exhaust gas generated in a heating furnace, and the combustion air A heat exchange system for recovering an array of hot combustion flue gases generated in a heating furnace comprising a regenerative heat exchanger connected to a supply line and an exhaust gas exhaust line, The heat storage heat exchanger is made of a ceramic material of a circular cross section and is capable of direct heat exchange, and a honeycomb heat storage layer formed therein, and a plurality of separation plates forming a plurality of sections by separating the heat storage body layer from the center in the circumferential direction; Heat exchange system for heat recovery of the heating furnace, characterized in that consisting of a rotating shaft formed in the center. The method of claim 1, And a protective tube is formed on an outer circumferential surface of the rotary shaft of the heat storage type heat exchanger. The method of claim 1, A heat exchanger for heat recovery of a heating furnace, characterized in that a damper for adjusting the flow rate is installed on the exhaust gas exhaust line, and a distributed control system (DCS) is installed for adjusting the opening amount of the damper. The method of claim 3, And a detection sensor for transmitting a measurement signal of the furnace pressure in the furnace to the distributed control system. The method of claim 1, A bypass exhaust line for exhausting the combustion exhaust gas is formed between the exhaust gas outlet of the furnace and the stack, and a damper is further provided on the bypass exhaust line to adjust the flow rate by controlling the DCS. Heat exchange system for heat recovery from furnace. 6. The method according to any one of claims 1 to 5, The regenerative heat exchanger is a mixture of the combustion air and exhaust gas therein by the rotation of the heat accumulator is supplied to the burner of the heating furnace through the combustion air supply line or the stack through the suction fan through the exhaust gas exhaust line Heat exchange system for heat recovery of the heating furnace, characterized in that discharged to.

Images