JP6400559B2 - Regenerative combustion furnace - Google Patents

Description

  The present invention relates to a regenerative combustion furnace used as a heating furnace, a melting furnace, an incinerator, a heat treatment furnace, and the like. Specifically, the heat storage and combustion air can be operated while continuously operating a single burner (combustion device) with a simple configuration. The present invention relates to a regenerative combustion furnace in which preheating can be performed simultaneously, and dust in exhaust gas is eliminated from combustion air.

  A regenerative combustion furnace stores the heat of exhaust gas discharged from the furnace, heats the combustion air with that heat, and supplies the combustion air preheated to a high temperature to the combustion section of the furnace burner to increase thermal efficiency. It is something to enhance. As conventional technology of this heat storage type combustion furnace, for example, there are those shown in Patent Documents 1 to 3 below.

  In the heat storage combustion apparatus described in Patent Document 1, two pairs of burners are installed in a combustion furnace, and the pairs of burners are alternately burned. Then, while one burner is burning, the heat storage body attached to the other burner absorbs the heat of the exhaust gas discharged from the combustion furnace, and the combustion air supplied to the other burner is absorbed by the other burner. It heats to high temperature with the heat | fever previously absorbed in the thermal storage body of the system which has this.

  On the other hand, the heat storage combustion system described in Patent Document 2 continuously operates a single burner. During the operation, the heat storage body arranged in one of the two heat storage paths absorbs the heat of the exhaust gas of the combustion furnace, and the combustion air supplied to the furnace is heated to a high temperature in the other heat storage path .

  The switching of the supply of exhaust gas and combustion air to the two heat storage paths in the heat storage combustion system of Patent Document 2 is performed using a switching valve such as a rotary valve.

  Moreover, the heat storage type burner described in patent document 3 arrange | positions a heat storage body in the discharge path (air distribution part) of the waste gas from the combustion chamber of a furnace, and can move the heat storage body to a heat exchange part. The combustion air supplied to the combustion chamber of the heating furnace is heated by the heat stored in the heat storage in the heat exchange section.

  Further, dust in the exhaust gas adhering to the heat storage body during heat storage is introduced when the heat storage body moves to the heat exchanging section and the cleaning air is blown out of the burner main body with the cleaning air. Yes.

JP 2000-273535 A Japanese Patent Laid-Open No. 10-73236 JP 2001-241646 A

  Since the heat storage combustion apparatus of Patent Document 1 performs combustion by two burners alternately, it is necessary to provide two burners that satisfy the required performance of the heating furnace, and the apparatus becomes complicated and expensive.

On the other hand, since the heat storage combustion system of Patent Document 2 operates the same burner continuously,
The number of burners, the exhaust gas exhaust blower, and the combustion air feed blower may be one each, and the apparatus can be simplified and the cost can be reduced.

  However, in the heat storage combustion system of Patent Document 2, the exhaust gas of the combustion furnace is caused to flow into the casing containing the heat storage body so that the heat in the exhaust gas is absorbed by the heat storage body, and then combustion air is introduced into the casing. Since the air is introduced and heated, dust or the like in the exhaust gas adheres to the surface of the heat storage body housed in the casing, and the operation of the heating furnace must be periodically stopped to remove the dust.

  It is also conceivable that dust attached to the surface of the heat storage body is peeled off from the heat storage body and heated into the combustion chamber of the heating furnace when the combustion air is heated by the heat storage body.

  The regenerative burner of Patent Document 3 allows continuous operation without the trouble of purifying the heat storage body by blowing dust and the like adhering to the surface of the heat storage body out of the main body of the burner with purification air, At the same time, the burner is reduced in size and cost.

  However, in the heat storage burner of Patent Document 3, since both the exhaust gas of the furnace and the combustion air are in contact with the heat storage body of the heat exchange unit, dust or the like adhering to the surface of the heat storage body is used for combustion by the heat storage body. It is conceivable that the air is peeled off from the heat storage body during the air heating and flows into the combustion chamber.

  In addition, when dust or the like attached to the surface of the heat accumulator is blown off with the purification air, it is considered that some heat of the heat accumulator is lost and the heating efficiency of the combustion air is lowered.

  Furthermore, the heat storage burner of Patent Document 3 requires a mechanism for moving the heat storage body from the exhaust gas passage to the heat exchange section and returning it from the heat exchange section to the exhaust gas passage after heat exchange, and there is still room for improvement with regard to simplification of the structure. Is leaving.

  Therefore, the present invention can continuously operate one burner, and further can heat the combustion air with the heat of the exhaust gas without moving the heat accumulator, and the dust in the exhaust gas is mixed with the combustion air. However, the issue is to provide a regenerative combustion furnace that is completely free.

  The regenerative combustion furnace of the present invention is a furnace provided with a combustion furnace equipped with a burner and a heat storage zone.

  The heat storage zone is composed of two exhaust gas discharge paths through which high-temperature exhaust gas discharged from the combustion furnace passes, and first and second combustion airs that are provided around each exhaust gas discharge path and separated from each other by a partition wall. A supply path, a heat-resistant heat insulating wall surrounding the first and second combustion air supply paths, inlets of the first and second combustion air supply paths provided on the heat-resistant heat insulating wall, and the inlet The first and second combustion air supply passages are combined with a switching mechanism that selectively switches the communication state.

  Each exhaust gas discharge path of the heat storage zone is composed of a plurality of heat-resistant pipes, each of which has an exhaust gas passage inside and penetrates the heat-resistant heat insulating wall, and the first and second combustion air supply paths are on the outlet side. Combustion air that is configured as a single common passage that reaches the fuel injection port of the burner and is introduced into the exhaust gas and the first and second combustion air supply passages through the heat-resistant pipe. After the heat exchange, the heated (preheated) combustion air in the first or second combustion air supply passage is swept away by the newly introduced combustion air and passed through the common passage. The fuel is supplied to the fuel injection port.

  The preheated combustion air can be supplied to the fuel injection port of the burner by using an air supply device such as a blower. The air supply device may be arranged upstream of the inlets of the first and second combustion air supply passages (the burner installation side is considered downstream).

  In this regenerative combustion furnace, the amount of heat recovered from the exhaust gas increases as the length of the heat-resistant pipe in the combustion air supply path is increased.

  The heat-resistant pipe that functions as a heat exchanger is preferably an alumina tube, silicon carbonitride tube, carbon tube, or the like that can withstand high temperatures, but depending on the temperature of the exhaust gas, a heat-resistant metal tube can also be used.

  The outer diameter and inner diameter of the heat-resistant pipe are not particularly limited, but if the pipe has an excessively large inner diameter, depending on the length in the combustion air supply path, the exhaust gas is discharged from the exhaust gas discharge path without sufficient heat exchange. Therefore, it is preferable to arrange a plurality of pipes having an inner diameter of about 20 mm to 150 mm with respect to one combustion air supply path.

  Combustion furnaces that use large-diameter heat-resistant pipes should have several thick pipes (for example, about 2 to 3 pipes), and combustion furnaces that use small-diameter heat-resistant pipes use thick-walled pipes. Since it is hard, you should increase the number of pipes installed.

  The switching mechanism may employ a shutter or a rotary valve. Among them, the one using a shutter is preferable because the degree of communication between the first and second combustion air supply passages can be adjusted.

  The adjustment of the degree of communication mentioned here is to make the inlet of the other combustion air supply path fully closed or slightly open at the position where the inlet of the one combustion air supply path is largely opened.

  In addition, it is preferable to provide a switching lid that selectively opens and closes the outlets of the two exhaust gas discharge paths.

  In the regenerative combustion furnace of the present invention, the heat in the exhaust gas is absorbed by the heat-resistant pipe when the exhaust gas discharged from the combustion furnace flows through the exhaust gas discharge path constituted by the heat-resistant pipe.

  And the combustion air in the 1st, 2nd combustion air supply path provided in the circumference | surroundings of the exhaust gas discharge path | route is heated with the heat.

  One of the first and second combustion air supply passages is closed in a state where the inlet is fully opened and the other is fully closed or slightly opened.

  Thereby, the combustion air in the combustion air supply path on the side where the inlet is closed is heated by the heat-resistant pipe that has absorbed the heat of the exhaust gas. Combustion air that has already been preheated in the combustion air supply passage where the inlet is open is swept away by the newly introduced combustion air from the open inlet and passes through the common passage to the burner. It is supplied to the fuel injection port.

  When there is almost no preheated combustion air in the combustion air supply passage with the inlet open, the opening and closing states of the inlets of the first and second combustion air supply passages are switched, and one of the combustion air supplies is supplied. While the preheated combustion air in the passage is being supplied to the fuel injection port of the burner, the preheated combustion air in the other combustion air supply passage preheated by the heat of the exhaust gas is supplied to the fuel injection port of the burner Is done.

Thus, the supply of preheated combustion air and the heat exchange between the exhaust gas and the combustion air are performed in two heat storage zones (a zone having a first combustion air supply path and a second combustion air supply path). In one zone), one burner can be operated continuously.

  Moreover, like patent document 3, combustion air can be heated with the heat | fever of waste gas, without moving a thermal storage body, and simplification of an installation and reduction of installation cost can be aimed at.

  The switching mechanism for switching the opening and closing states of the inlets of the first and second combustion air supply passages may be a set of a mechanism that employs a shutter and a rotary valve with a simple structure, which can be expected to reduce equipment costs.

  Further, since the exhaust gas from the combustion furnace passes through the inside of the heat-resistant pipe and the combustion air passes through the outside of the heat-resistant pipe, there is no mixing of dust or the like in the exhaust gas into the combustion air.

  Note that a combustion furnace that slightly opens the inlet of the other combustion air supply passage when the inlet of the one combustion air supply passage is sufficiently large is opened from the slightly open inlet to the other combustion air. Air flows into the supply path. With this cooling effect, it is possible to prevent overheating of the heat-resistant pipes and the like arranged in the heat storage zone on the side where heat exchange is performed, and to suppress the life reduction.

It is a principle figure of the regenerative combustion furnace of this invention. It is sectional drawing which shows the outline | summary of the principal part of an example of the thermal storage type combustion furnace of this invention. It is sectional drawing along the III-III line of FIG. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. It is sectional drawing along the VV line of FIG. It is sectional drawing along the VI-VI line of FIG. It is sectional drawing along the VII-VII line of FIG. It is sectional drawing which shows the outline | summary of the principal part of the other example of the thermal storage type combustion furnace of this invention.

  Embodiments of a regenerative combustion furnace according to the present invention will be described below with reference to FIGS.

  The illustrated regenerative combustion furnace 1 includes a combustion furnace 3 provided with a burner 2 and a heat storage zone 4 that performs heat exchange.

The heat storage zone 4 includes two exhaust gas discharge paths _5-1 , _5-2 , first and second combustion air supply paths _7-1 , _7-2, and first and second combustion air. First and second combustion provided in the heat-resistant heat insulating wall 9 having a heat-resistant heat-insulating wall 9 surrounding the supply path, a partition wall 9a (see FIGS. 2, 3, and 5 to 7) and a shielding wall 9b. combinations inlet _28-1 of use the air supply _passage, and _8-2, the inlet _{8 -1, 8 -2} combustion air supply passage _7-1, a switching mechanism 10 for switching the communicating state selective for _{7 -2} It has become a thing. 4 to 7, reference numeral 3 a denotes an elevating door that closes the inlet of the combustion furnace 3, and 11 denotes an exhaust gas introduction path from the combustion furnace 3.

The shielding wall 9b included in the heat-resistant heat insulating wall 9 is a grate-like wall that separates the first and second combustion air supply passages 7 _-1 and 7 _-2 from the exhaust gas introduction passage. Has a hole.

  The burner 2 showed what burns the fuel gas supplied from the gas supply apparatus 12 (refer FIG. 1) by injecting into the furnace. Reference numeral 13 in FIG. 1 denotes a seed fire nozzle that injects a fuel gas for seed fire.

The two exhaust gas discharge paths 5 _-1 and 5 _-2 are paths through which the high-temperature exhaust gas discharged from the combustion furnace 3 passes, and each penetrates the shielding wall 9b and the top wall 9c of the heat-resistant heat insulating wall 9. A plurality of heat resistant pipes 6 each having an exhaust gas passage are formed inside.

The first and second combustion air supply passages 7 _-1 and 7 _-2 are air passages provided around the heat-resistant pipes 6 constituting the exhaust gas discharge passages 5 _-1 and _5-2, and both of them. The portions other than the outlet side are separated from each other by a partition wall 9 a of the heat-resistant heat insulating wall 9.

Further, the outlet sides of the first and second combustion air supply passages 7 _-1 and 7 _-2 are configured as a single common passage 14 where the supply passages merge to form a fuel injection port of the burner 2. Has reached.

The heat-resistant pipe 6 constituting the exhaust gas discharge paths 5 _-1 and 5 _-2 can sufficiently cope with a high temperature exceeding 1200 ° C. when an alumina tube or a silicon carbonitride tube is used. However, depending on the temperature of the exhaust gas, a pipe formed of a heat-resistant alloy such as Inconel (Special Metals: trademark) can also be used.

  If the heat-resistant pipe 6 is too thin, the passage of the exhaust gas deteriorates due to adhesion of dust or the like in the exhaust gas. Conversely, if the heat-resistant pipe 6 is too thick, the heat in the exhaust gas is sufficiently applied to the heat-resistant pipe 6 depending on the length of the exhaust gas discharge path. Since the exhaust gas is discharged to the outside through the exhaust gas discharge path before being absorbed, it is preferable to use the one having an inner diameter of about 20 mm to 150 mm.

First, second combustion air supply passage _{7 -1, 7 -2,} cross-sectional area exhaust gas discharge path _5-1 in the _drawings, the effective cross-sectional area of the _5-2 and (total cross-sectional area of each path) Same However, there is no particular limitation on the size of the passage cross-sectional area.

  If the passage cross-sectional area is large and the length of the exhaust gas discharge path is long, the amount of air in the combustion air supply path in the two heat storage zones increases, but the heat exchange time in the two heat storage zones is In this case, the combustion air can be heated to a target temperature by adjusting the heat exchange time between the exhaust gas and the combustion air.

In the case of the illustrated regenerative combustion furnace, the switching mechanism 10 slides the shutter 10a with a drive source 10b such as a cylinder actuator to cause the inlet _8-1 of the first combustion air supply path _7-1 and the second combustion. closed state of the inlet 8 _-2 use air supply passage 7 _-2 employs what selectively switching.

Incidentally, the shutter 10a used here, wide open inlet 8 _-1 when slid in the A direction in FIG. 7, closing the inlet 8 _-2 incomplete state (slightly open). Further, when the shutter 10a slides in the direction B in FIG. 7, the entrance _8-2 is largely opened, and the entrance _8-1 is closed in an incomplete state.

  In this way, if the inlet on the closed side is opened slightly, a little air flows into the combustion air supply passage on the zone side where the heat exchange between the exhaust gas and the combustion air is performed from the slightly opened port. Overheating of the heat-resistant pipe 6 disposed on the zone side where heat exchange is performed is prevented by the cooling effect of the inflowing air.

  When the heat-resistant pipe 6 is made of a material that can sufficiently withstand a high temperature exceeding 1200 ° C., for example, the inlet of the combustion air supply passage on the zone side where heat exchange is performed is completely closed. It doesn't matter.

  In this case, an electromagnetic drive system or an electric rotary valve can also be used as the switching mechanism 10.

Further, regenerative combustion furnace 1 shown, the inlet 8 _-1, the air duct 16 and the air supply unit 15 such as a blower shown in FIG. 1 upstream of _8-2 installed, first, second combustion The combustion air preheated in one of the air supply passages 7 _-1 and 7 _-2 is swept away by the combustion air newly introduced through the air supply device 15 and supplied to the fuel injection port of the burner via the common passage 14. It has become a thing.

Regenerative combustion furnace 1 illustrated configured as described above, first, second combustion air supply passage 7 _-1, open one of the inlet 7 _-2, open the other inlet fully closed, or slightly Close and start operation.

  For a while after the start of operation, combustion air that has not been preheated is supplied to the fuel injection port of the burner 2. Therefore, high thermal efficiency cannot be expected at the beginning of operation.

  However, after a certain period of time, the combustion air is heated by the exhaust gas in one heat storage zone during that time, so that the combustion air in the combustion air supply path on the side where the inlet is closed becomes high temperature. .

  Thus, thereafter, the combustion furnace is continuously operated while supplying the high-temperature preheated air to the combustion furnace by alternately switching the preheating of the combustion air and the supply of the preheated combustion air in the two heat storage zones. be able to.

8, the regenerative combustion furnace 1 in FIG. 1 to FIG. 7, is obtained by additionally provided switching lid 17 for selectively opening and closing the outlet of the exhaust gas discharge path _{5-1, 5-2.} The switching lid 17 is provided with the switching mechanism 10.
This is a mechanism including a power source (not shown) that operates in synchronization with the operation of the drive source 10b.

The switching lid 17 closes the outlet of the exhaust gas discharge path _5-2 when the shutter 10a is opened the inlet _8-2, opening the outlet of the exhaust gas discharge passage _25-1.

Further, the shutter 10a is pulled to the left in the drawing the inlet _8-2 is closed in FIG. 8, the inlet 8 _-1 is opened, in a counterclockwise direction indicated by the arrow to the support shaft as a fulcrum rotation to close the outlet of the exhaust gas discharge passage _5-1, opening the outlet of the exhaust gas discharge path _5-2.

  As a result, the exhaust gas from the combustion furnace 3 flows all through the exhaust gas discharge path on the side where heat storage and heat exchange are performed, and the heat in the exhaust gas is used for preheating combustion air without waste, and the preheating effect is further enhanced.

DESCRIPTION OF SYMBOLS 1 Thermal storage type combustion furnace 2 Burner 3 Combustion furnace 3a Door 4 Thermal storage zone _5-1 , _5-2 Exhaust gas discharge path 6 Heat-resistant pipe _7-1 First combustion air supply path _7-2 Second combustion air supply path 8 _-1 , 8 _-2 inlet 9 heat-resistant heat insulating wall 9a partition wall 9b shielding wall 9c top wall 10 switching mechanism 10a shutter 10b drive source 11 exhaust gas introduction path 12 gas supply device 13 seed fire nozzle 14 common passage 15 air supply device 16 Air duct 17 Switching lid

Claims (6)

A furnace equipped with a combustion furnace (3) equipped with a burner (2) and a heat storage zone (4),
The heat storage zone (4) has two exhaust gas discharge paths (5 _-1 , 5 _-2 ) arranged in parallel through which high-temperature exhaust gas discharged from the combustion furnace (3) passes, and around each exhaust gas discharge path. The first and second combustion air supply passages (7 ₋₁ , 7 ₋₂ ) and the first and second combustion air supply passages enclosed by the partition wall (9a) are surrounded by the first and second combustion air supply passages. The heat-resistant heat insulating wall (9), the inlets (8 ₋₁ , 8 ₋₂ ) of the first and second combustion air supply passages provided on the heat-resistant heat insulating wall, and the first and second of the inlets And a switching mechanism (10) that selectively switches the communication state with respect to the combustion air supply passages ( _7-1 , _7-2 ).
The heat storage zone (4) Each exhaust gas discharge passage (5 _{-1, 5 -2)} of the inner flow towards the outlet at the upper end of the exhaust gas introduced from the lower end I Do with the exhaust gas passage, each of the heat-resistant formed by a plurality of heat pipes passing through the heat insulating wall (9) (6), wherein the heat pipe of each exhaust gas discharge passage _{(5 -1, 5 -2)} (6) are the same diameter and the same number Yes,
The first and second combustion air supply passages ( _7-1 , _7-2 ) are configured as a single common passage (14) on the outlet side, and the common passage serves as a fuel injection port of the burner (2). Finally, heat exchange between the exhaust gas and the combustion air introduced into the first and second combustion air supply passages ( _7-1 , _7-2 ) via the heat-resistant pipe (6) is performed alternately . The heated air in the first or second combustion air supply passage (7 ₋₁ , 7 ₋₂ ) is swept away by the newly introduced combustion air and passes through the common passage (14) to the burner. A regenerative combustion furnace configured to be supplied to the fuel injection port of (2). The regenerative combustion furnace according to claim 1, further comprising a switching lid (17) that selectively opens and closes the outlets of the two exhaust gas discharge paths ( _5-1 , _5-2 ).   The regenerative combustion furnace according to claim 1 or 2, wherein the heat-resistant pipe (6) is one of an alumina tube, a silicon carbonitride tube, a carbon tube, or a heat-resistant metal tube.   The regenerative combustion furnace according to any one of claims 1 to 3, wherein the heat-resistant pipe (6) is a pipe having an inner diameter of 20 mm to 150 mm.   The regenerative combustion furnace according to any one of claims 1 to 4, wherein the switching mechanism (10) includes a shutter (10a) and a drive source (9b) for sliding the shutter. Combustion of the other at the position where the shutter (10a) of the switching mechanism (10) has opened one of the inlets of the first and second combustion air supply passages ( _7-1 , _7-2 ). The regenerative combustion furnace according to claim 5, wherein the inlet of the air supply passage is fully closed or slightly opened.

Images