Combustion apparatus

Abstract

The present invention relates to a combustion apparatus capable of reducing the emission amount of nitrogen oxide and enabling stable combustion in the entire area of a set load. The combustion apparatus includes: a premixing chamber for premixing air and a gas; a blower for supplying a mixed-gas of the air and the gas to a burner; a combustion chamber for burning the mixed-gas by ignition of the burner; a heat exchanger for exchanging heat with water by using combustion heat in the combustion chamber; and an exhaust gas discharge part for discharging the exhaust gas passing through the heat exchanger, wherein the premixing chamber is formed in a Venturi shape having a throat part of which the cross-section area is tapered between an inlet and an outlet through which the air passes, the throat part of the premixing chamber being connected to a gas supply part for supplying a gas for combustion, and to an exhaust gas recirculation tube to which some of the exhaust gas having passed through the heat exchanger is introduced in proportion to differential pressure according to the flow rate of the mixed-gas passing through the throat part.

Claims

1. A combustion apparatus comprising: a premixing chamber in which air is mixed with a gas; a blower for supplying the mixed-gas of the air and the gas to a burner; a combustion chamber in which combustion is performed by ignition of the burner; a heat exchanger in which water is heat-exchanged with combustion heat of the combustion chamber; an exhaust gas discharge part from which an exhaust gas passing through the heat exchanger is discharged, wherein the premixing chamber has a venturi shape having a throat part, which is gradually reduced in section area from an inlet and an outlet of the premixing chamber to a central portion thereof, between the inlet and the outlet through which the air passes, and a gas supply part supplying a combustion gas and an exhaust gas recirculation tube are connected to the throat part of the premixing chamber so that a portion of the exhaust gas passing through the heat exchanger is introduced in proportion to a differential pressure according to a flow rate of the mixed-gas passing through the throat part, a mixed-gas adjusting part opening and closing a flow passage of the air and the gas passing through the premixing chamber to adjust a supply flow rate of the mixed-gas.

2. The combustion apparatus of claim 1, wherein the premixing chamber is divided into two sides, a first passage and a second passage, by a partition member therebetween, the combustion gas introduced through the gas supply part is supplied to a first gas supply hole connected to the first passage and a second gas supply hole connected to the second passage, and the exhaust gas recirculation tube is constituted by a first exhaust gas recirculation tube connected to the throat part of the first passage and a second exhaust gas recirculation tube connected to the throat part of the second passage.

3. The combustion apparatus of claim 2, wherein a flow passage of the air and the gas of the first passage is in an opened state all the time, and the mixed-gas adjusting part opens and closes a flow passage of the air passing through the second passage and a flow passage of the gas connected to the second passage through the second gas supply hole.

4. The combustion apparatus of claim 3, wherein the first and second gas supply holes pass through one side surface of the first passage, a first gas supply passage extending from the first gas supply hole to the partition member across the first passage and a second gas supply passage passing through the partition member from the second gas supply hole across the first passage to communicate with the second passage are defined in the throat part of the first passage, a first gas jet hole is defined in the first gas supply passage toward an outlet-side of the first passage, and a second gas connection hole is defined in an end of the second gas supply passage passing through the partition member toward the second passage.

5. The combustion apparatus of claim 4, wherein the mixed-gas adjusting part comprises: a first opening/closing member for opening and closing the flow passage of the air passing through the second passage; a second opening/closing member for opening and closing the second gas connection hole, and wherein the first and second opening/closing members may be lined to each other and simultaneously opened and closed.

6. The combustion apparatus of claim 5, wherein the first opening/closing member comprises: a main body coupled to a rotation shaft of a driving part and transversally disposed on the throat part of the second passage; blades coupled to an outer surface of the main body to face each other and have a size corresponding to that of an opened transversal section of the throat part of the second passage, and wherein the second opening/closing member reciprocates in a transversal direction according to rotation of the first opening/closing member.

7. The combustion apparatus of claim 6, wherein, on the main body of the first opening/closing member, a first tip portion protruding toward the second opening/closing member and a first bottom portion having an oppositely recessed shape with respect to the first tip portion are alternately disposed at an angle of 90° along a circumferential direction, a first inclined portion having a recessed shape is disposed between the first tip portion and the first bottom portion, a second tip portion, a second bottom portion, and a second inclined portion each of which has a shape corresponding to that of each of the first tip portion, the first bottom portion, and the first inclined portion are disposed on the main body (331) of the second opening/closing member, and the second opening/closing member is elastically supported so that the second opening/closing member is pressed toward the first opening/closing member by an elastic member.

8. The combustion apparatus of claim 7, wherein a sealing member for maintaining air-tightness when the second gas connection hole is sealed is coupled to the second opening/closing member.

9. The combustion apparatus of claim 7, wherein, when the first tip portion of the first opening/closing member contacts the second tip portion of the second opening/closing member, the blades of the first opening/closing member are parallelly disposed with respect to a transversal section of the second passage to block the flow of the air of the second passage, and at the same time, the second opening/closing member is closely attached to the second gas connection hole to block the flow of the gas passing through the second gas connection hole, and when the first tip portion of the first opening/closing member contacts the second bottom portion of the second opening/closing member, and the first bottom portion of the first opening/closing member contacts the second tip portion of the second opening/closing member, the blades of the first opening/closing member are vertically disposed with respect to the transversal section of the second passage to open the second passage, and at the same time, the second opening/closing member is spaced apart from the second gas connection hole to open the second gas connection hole.

10. The combustion apparatus of claim 7, wherein a guide member accommodating the second opening/closing member and the elastic member therein to guide a reciprocating motion of the second opening/closing member is disposed on the throat part of the second passage, and a second gas jet hole is defined in the guide member toward an outlet-side of the second passage.

11. The combustion apparatus of claim 10, wherein protruding pieces for supporting one end of the elastic member are disposed in plurality on an edge of the main body of the second opening/closing member along a circumferential direction, and a flange part for supporting the other end of the elastic member and that is closely attached on a circumferential surface of the second gas connection hole is disposed in the guide member.

12. The combustion apparatus of claim 11, wherein a plurality of guide grooves for guiding the plurality of protruding pieces to move in a horizontal direction are defined in an inner surface of the guide member in longitudinal direction.

13. The combustion apparatus of claim 11, wherein fixing projections and fixing grooves that are fitted and coupled to each other are respectively formed on the flange part of the guide member and the circumferential surface of the second gas connection hole to fix the guide member.

14. A combustion apparatus comprising: a premixing chamber in which air is mixed with a gas; a blower for supplying the mixed-gas of the air and the gas to a burner; a combustion chamber in which combustion is performed by ignition of the burner; a heat exchanger in which water is heat-exchanged with combustion heat of the combustion chamber; and an exhaust gas discharge part from which an exhaust gas passing through the heat exchanger is discharged, wherein the premixing chamber has a venturi shape having a throat part, which is gradually reduced in section area from an inlet and an outlet of the premixing chamber to a central portion thereof, between the inlet and the outlet through which the air passes, and a gas supply part supplying a combustion gas and an exhaust gas recirculation tube are connected to the throat part of the premixing chamber so that a portion of the exhaust gas passing through the heat exchanger is introduced in proportion to a differential pressure according to a flow rate of the mixed-gas passing through the throat part, wherein the premixing chamber has a venturi shape having a single passage.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic view of a combustion apparatus according to the related art.

(2) FIG. 2 is a perspective view of a combustion apparatus according to an embodiment of the present invention.

(3) FIG. 3 is an enlarged perspective view of a premixing chamber and a blower of FIG. 2.

(4) FIGS. 4 and 5 are an exploded perspective view of the premixing chamber and a mixed-gas adjusting part.

(5) FIG. 6 is a plane view of the premixing chamber at a high power load.

(6) FIG. 7 is a cross-sectional view taken along line A-A of FIG. 6.

(7) FIG. 8 is a cross-sectional view taken along line B-B of FIG. 6.

(8) FIG. 9 is a cross-sectional view taken along line C-C of FIG. 6.

(9) FIG. 10 is a plane view of the premixing chamber at a low power load.

(10) FIG. 11 is a cross-sectional view taken along line D-D of FIG. 10.

(11) FIG. 12 is a cross-sectional view of E-E of FIG. 10.

(12) FIG. 13 is a graph showing correlation of heat amount according to variation of the load.

(13) FIG. 14 is a cross-sectional view of a premixing chamber according to another embodiment of the present invention.

DESCRIPTIONS OF REFERENCE NUMERALS IN THE ACCOMPANYING DRAWINGS

(14) TABLE-US-00001 10: Blower 20: Gas supply part 20: Gas supply tube 22: Valve 30: Burner 40: Combustion chamber 50: Heat exchanger 61: Heating water return tube 62: Heating water supply tube 70: Duct 110: Air intake hole 120: Air intake preheating part 130: Air supply tube 140: Blower 150: Mixed-gas supply tube 160: Combustion chamber 170: Heat exchanger 180: Exhaust gas discharge part 190: Duct 200: Premixing chamber 201: Partition member 210: First passage 211: First premixing chamber 220: Second passage 221: Second premixing chamber 230: Gas supply part 231: First gas supply hole 231a: First gas supply passage 231b: First gas jet hole 232: Second gas supply hole 232a: Second gas supply passage 232b: Second gas connection hole 300: Mixed-gas adjusting part 310: Driving part 311: Motor 311a: Rotation shaft 312: Bracket 320: First opening/closing member 321: Main body 321a: Rotation shaft coupling groove 322: First cam-shaped part 322a: First tip portion 322b: First bottom portion 322c: First inclined portion 323: Blade 330: Second opening/closing member 331: Main body 332: Second cam-shaped part 332a: Second tip portion 332b: Second bottom portion 332c: Second inclined portion 333: Protruding piece 340: Sealing member 350: Elastic member 360: Guide member 361: Main body 362: Flange part 362a, 362b: Fixing projections 363: Guide groove   364: Second gas jet hole 400: Exhaust gas recirculation tube 401: First exhaust gas recirculation tube 402: Second exhaust gas recirculation tube

MODE FOR CARRYING OUT THE INVENTION

(15) Hereinafter, components and effects of a combustion apparatus according to preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(16) Referring to FIG. 2, the combustion apparatus according to an embodiment of the present invention includes an air intake hole 110 to which external air is introduced, an air preheating part 120 defining a supply channel of the air introduced through the air intake hole 110 and at the same time defining an exhaust channel of an exhaust gas, which is separated from the supply channel of the air; an air supply tube 130 through which the air passing through the air preheating part 120 moves a premixing chamber 200 in which the air introduced through the air supply tube 130, a combustion gas, and a recirculated exhaust gas are premixed a mixed-gas adjusting part 300 adjusting a section area of a passage through which the air and the gas flow in the premixing chamber 200 to adjust a supply flow rate of the mixed-gas, a blower 140 transferring the mixed-gas to a burner, a combustion chamber 160 in which the mixed-gas supplied thorough the supply tube 150 by being transferred from the blower 140 is burnt by ignition of the burner, a heat exchanger 170 heating water circulating therein by using combustion heat generated from the combustion chamber 160, an exhaust gas discharge part 180 through which the exhaust gas that is heat-exchanged in the heat exchanger 170 passes, a duct 190 from which the exhaust gas that is heat-exchanged with the air while passing through the air preheating part 120 is discharged, and an exhaust gas recirculation tube 400 to which a portion of the exhaust gas passing through the exhaust gas discharge part 180 recirculates to be introduced into the premixing chamber 200.

(17) Referring to FIG. 3, the premixing chamber 200 is connected to an inlet-side of the blower 140. An inner space of the premixing chamber 200 is divided into a first passage 210 and a second passage 220 by a partition member 201 therebetween. The premixing chamber 200 has a venturi shape having a throat part, which is gradually reduced in section area from an inlet and an outlet toward the center thereof, in a central portion between the inlet to which the air is introduced and the outlet from which the mixed-gas is discharged toward the blower 140. That is, the premixing chamber 200 has a shape in which each of the inlet and the outlet of the air has a relatively wide section area, and the premixing chamber 200 gradually decreases in section area from the inlet and the outlet toward the throat part of the center thereof.

(18) A gas supply part 230 connected to a combustion gas supply tube (not shown) is disposed on one side of the throat part of the premixing chamber 200. Also, a mixed-gas adjusting part 300 is disposed on the other side of the throat part. A first exhaust gas recirculation tube 401 is connected to the throat part of the first passage 210, and a second exhaust gas recirculation tube 402 is connected to a front side of the throat part of the second passage 220.

(19) A first gas supply hole 231 connected to the first passage 210 and a second gas supply hole 232 connected to the second passage 220 are defined in the gas supply part 230.

(20) The first passage 210 of the premixing chamber 200 has a flow passage of the air and the gas that is in an opened state all the time. Also, a flow passage of the air and the gas of the second passage 220 is opened when a combustion load is more than a set load and is closed when the combustion load is less than the set load, by an operation of the mixed-gas adjusting part 300.

(21) The exhaust gas recirculation tubes 400 (401, 402) defines a flow passage through which a portion of the heat-exchanged exhaust gas recirculates to be introduced into the premixing chamber 200. An inlet of the exhaust gas recirculation tube 400 may pass through the heat exchanger 170 and disposed on a predetermined position between the exhaust gas discharge part 180 and the duct 190.

(22) The mixed-gas of the air, the combustion gas, and the recirculated exhaust gas premixed with each other in the premixing chamber 200 may be suctioned into the blower 140 by rotation of a fan disposed in the blower 140 and then be supplied to the mixed-gas supply tube 150 through a mixed-gas discharge hole 141.

(23) Like this, according to the premixing chamber 200 having a venturi shape and the structure in which the gas supply parts 230 (231, 232) and the exhaust gas recirculation tube 400 (401, 402) are connected to the one side of the throat part, the air passing through the throat part has a flow rate that is relatively higher than that of the air at each of the inlet and outlet of the premixing chamber 200 and a pressure that is lower than that of each of the inlet and outlet of the premixing chamber 200, and thus a differential pressure may occur between the inlet and outlet of the premixing chamber 200 and the throat part. Also, when the air is adjusted in flow rate by controlling RPM of the blower 140, the gas and the exhaust gas introduced into the throat part having a relatively low pressure due to the differential pressure are also proportionally controlled in flow rate so that the flow rate is maintained in a predetermined air-fuel ratio.

(24) Hereinafter, components of the premixing chamber 200 and the mixed-gas adjusting part 300 and coupling relationship between the premixing chamber 200 and the mixed-gas adjusting part 300 will be described in detail with reference to FIGS. 4, 5, and 7.

(25) First, referring to FIG. 7, in the premixing chamber 200, the first and second passages 210 and 220 partitioned into two sides in the premixing chamber 200 by the partition member 201 are defined, and the throat part having a relatively narrow section area when compared to the inlet and the outlet of the premixing chamber 200 is defined in each of a central portion of the first passage 210 and a central portion of the second passage 220. A first gas supply hole 231 and a second gas supply hole 232 spaced upward from the first gas supply hole 231 are defined in one side surface of the throat part of the first passage 210.

(26) A first gas supply passage 231a is defined from the first gas supply hole 231 to the partition member 201 across the first passage 210. A first gas jet hole 231b is defined in the first gas supply passage 231a toward an outlet-side of the first passage 210.

(27) A second gas supply passage 232a is defined from the second gas supply hole 232 to pass through the partition member 201 across the first passage 210 to communicate with the second passage 220. A second gas connection hole 232b is defined on an end of the second gas supply passage 232a passing through the partition member 201 toward the second passage 220.

(28) The first and second gas supply passages 231a and 232a are parallelly disposed to be vertically spaced apart from each other. A flow passage of the air is defined in a space between an inner wall of the first passage 210 and the first and second gas supply passages 231a and 232a. In the first passage 210, each of the flow passage of the air and the flow passage of the gas are in opened state all the time.

(29) The mixed-gas adjusting part 300 includes a first opening/closing member 320 for opening and closing the flow passage of the air passing through the second passage 220 and a second opening/closing member 330 for opening and closing the second gas connection hole 232b. Here, the first and second opening/closing members 320 and 330 are linked to each other and opened and closed at the same time.

(30) The first opening/closing member 320 includes a main body 321 coupled to a rotation shaft 311a of a driving part 310 and transversally disposed in the throat part of the second passage 220 and blades 323 coupled to an outer surface of the main body 321 in a distance at an angle of 180°. The blades 323 have a size corresponding to that of an opened transversal section of the throat part of the second passage 220. Thus, when the blade 323 is disposed in parallel to the transversal section of the throat part in a transversal direction, the flow passage of the air of the second passage 220 may be blocked. Also, when the blade 323 is vertically disposed to stand upright with respect to the transversal section of the throat part, the flow passage of the air is opened through a space spaced apart form an inner side surface of the second passage 220.

(31) The driving part 310 includes a motor 311 and a bracket 312 inserted and coupled to a coupling hole 250 defined in one side surface of the premixing chamber 200 in order to fix the motor 311 to the one side of the premixing chamber 200 by passing the rotation shaft 311 therethrough. The rotation shaft 311a is fitted and coupled to a rotation shaft coupling groove 321a defined in the main body 321 of the first opening/closing member 320 to allow the first opening/closing member 320 to rotate when the motor 311 is driven.

(32) The second opening/closing member 330 is linked to rotation of the first opening/closing member 320 to reciprocate in a transversal direction to open and close the second gas connection hole 232b of the second gas supply hole 232. Also, a sealing member 340 for maintaining air-tightness when the second gas connection hole 232b is sealed is disposed on the second opening/closing member 330.

(33) A first cam-shaped part 322 in which a first tip portion 322a protruding toward the second opening/closing member 330 and a first bottom portion 322b oppositely recessed with respect to the first tip portion 322a are alternately disposed at an angle of 90° along a circumferential direction, and a first inclined portion 322c having a concave shape is disposed between the first tip portion 322a and the first bottom portion 322b is disposed on the main body 321 of the first opening/closing member 320.

(34) A second cam-shaped part 332 having a second tip portion 322a, a second bottom portion 332b, and a second inclined portion 332c each of which has a shape corresponding to that of each of the first tip portion 322a, the first bottom portion 322b, and the first inclined portion 322c is disposed on the main body 331 of the second opening/closing member 330. Also, the second opening/closing member 330 is elastically supported so that the second opening/closing member 330 is pressed toward the first opening/closing member 320 by an elastic member 350. The second opening/closing member 330 may reciprocate toward the second gas connection hole 232b or in a direction far away from the second gas connection hole 232b according to positions of the first and second cam-shaped parts 322 and 332 when the first opening/closing member 320.

(35) Also, a guide member 360 accommodating the second opening/closing member 330 and the elastic member 350 therein to guide a reciprocating motion of the second opening/closing member 330 is disposed on the throat part of the second passage 220. A second gas jet hole 364 is defined in the guide member 360 toward and outlet-side of the second passage 220.

(36) Protruding pieces 333 (333a, 333b) for supporting one end of the elastic member 350 are disposed on an edge of the main body 331 of the second opening/closing member 330 along a circumferential direction. A flange part 362 supporting the other end of the elastic member 350 and closely attached to a circumferential surface of the second gas connection hole 232b is disposed in the guide member 360.

(37) Also, a plurality of guide grooves 363 (363a, 363b) for guiding the plurality of protruding pieces 333 (333a, 333b) to reciprocate in a horizontal direction are defined in an inner surface of the guide member 360 along a longitudinal direction. Fixing projections 362a and 362b and fixing grooves (not shown) that are fitted and coupled to each other are respectively formed on the flange part 362 of the guide member 360 and the circumferential surface of the second gas connection hole 232b. Thus, the guide member 360 is fixed to the partition member 201 at a correct position.

(38) Hereinafter, effects of the present invention will be described.

(39) Referring to FIGS. 6 to 9, when the set load is in a high power state, the blade 323 of the first opening/closing member 320 is vertically disposed to stand upright with respect to the transversal section of the second passage 220 to open the flow passage of the air passing through the second passage 220 and simultaneously to cause a phase difference between the first and second tip portions 322a and 332a at an angle of 90°. Here, the first tip portion 322a of the first opening/closing member 320 contact the second bottom portion 332b of the second opening/closing member 330, and at the same time, the first bottom portion 322b of the first opening/closing member 320 contact the second tip portion 332a of the second opening/closing member 330. Also, the second opening/closing member 330 move in a direction far away from the second gas connection hole 232b by an elastic force of the elastic member 350 to open the second gas connection hole 232b. Thus, the air, the gas, and the recirculated exhaust gas may be introduced through the second passage 330 as well as the first passage 320 and mixed with each other.

(40) In this case, when the air is introduced through the first passage 210 to pass through the throat part of the first passage 210, the combustion gas that is introduced through the first gas supply hole 231 due to the differential pressure generated in the throat part passes through the first gas supply passage 231a and is jetted to the first premixing chamber 211 through the first gas jet hole 231b and simultaneously mixed with a portion of the exhaust gas introduced through the first exhaust gas recirculation tube 401 and then is discharged through the outlet of the first passage 210. At the same time, when the air is introduced through the second passage 220 to pass through the throat part of the second passage 220, the combustion gas that is introduced through the second gas supply hole 232 due to the differential pressure generated in the throat part is jetted to the second premixing chamber 221 through the second gas supply passage 232a, the second gas connection hole 232b, and the second gas jet hole 364 and simultaneously mixed with a portion of the exhaust gas introduced through the second exhaust gas recirculation tube 402 and is discharged through the outlet of the second passage 220.

(41) Referring to FIGS. 10 to 12, when the set load is in a low power state, the blade 323 of the first opening/closing member 320 is horizontally disposed in a transversal-section direction of the second passage 220 to block the flow of the air through the second passage 220, and at the same time, the first tip portion 322a of the first opening/closing member 320 contact the second tip portion 332a of the second opening/closing member 330 at the same phase. Here, the second opening/closing member 330 moves toward the second gas connection hole 232b regardless of the elastic force of the elastic member 350 to block the second gas connection hole 232b by the sealing member 340 coupled to the second opening/closing member 330.

(42) Thus, the air, the gas, and the recirculated exhaust gas may be supplied only through the first passage 320, and the supply of the air, the gas, and the exhaust gas through the second passage 330 may be blocked. In this case, when the air is introduced through the first passage 210 to pass through the throat part of the first passage 210, the combustion gas that is introduced through the first gas supply hole 231 due to the differential pressure generated in the throat part passes through the first gas supply passage 231a and is jetted to the first premixing chamber 211 through the first gas jet hole 231b and simultaneously mixed with a portion of the exhaust gas introduced through the first exhaust gas recirculation tube 401 and is discharged through the outlet of the first passage 210.

(43) FIG. 13 is a graph showing correlation of heat amount according to variation of the load. When the set load is in a low power (first stage) state, only the first passage 210 is opened, and when the set load is in a high power (second stage) state, both of the first and second passages 210 and 220 are opened. Also, the mixed-gas of the air, the combustion gas, and the recirculated exhaust gas having a uniform air-fuel ratio may be supplied by controlling the RPM of the blower 140 to secure a preset heat amount.

(44) As described above, according to the embodiments of the present invention, the premixing chamber 200 may have a venture structure partitioned into two stages, and the first passage 210 may be in an opened state all the time, and the second passage 220 may be opened only at the time of high power load according to a combustion load area, and also a portion of the exhaust gas may recirculate to supply the mixed-gas in which the air, the combustion gas, and the exhaust gas are mixed with each other. Thus, combustion system that is reduced in flame temperature to significantly reduce the emission amount of nitrogen oxide and improved in combustion efficiency by perfect combustion and stable over an entire load area from the high power load to the low power load may be realized.

(45) In the above-describe embodiments, although the premixing chamber 200 has a venturi structure that is partitioned into the two stages, which are the first passage 210 and the second passage 220, as illustrated in FIG. 14, the premixing chamber 200 according to the present invention may have a single passage venturi shape in which the gas supply part 230 and the exhaust gas recirculation tube 400 are connected to the throat part. In this case, the exhaust may recirculate in proportional to the differential pressure between the air and the gas passing through the throat part and then be introduced and mixed to supply the mixed-gas in which the air, the combustion gas, and the exhaust gas are mixed with each other at a uniform air-fuel ratio.