WO2007138962A1

WO2007138962A1 - Combustor

Info

Publication number: WO2007138962A1
Application number: PCT/JP2007/060565
Authority: WO
Inventors: Saburo Maruko; Tokio Naoi; Shingo Komori; Takahiko Matsuda; Yoshinori Yamazaki
Original assignee: Nippon Chemical Plant Consultant Co., Ltd.
Priority date: 2006-05-30
Filing date: 2007-05-17
Publication date: 2007-12-06
Also published as: CA2649212A1; KR20090025272A; CN101443593A; JP2007322019A; US20090239181A1; EP2023040A1

Abstract

A combustor comprising combustion unit (11) and, linked thereto, fuel supply unit (12) for supplying of a fuel/air mixture gas containing a fuel mixed with air, wherein the fuel supply unit consists of venturi tube type mixer (23) with fuel supply aperture (25) disposed along the inner circumferential surface at a throat portion; combustion air supply aperture (31) connected to the base end portion of the venturi tube type mixer; and an igniter disposed so as to generate spark at the distal end portion of the venturi tube type mixer, and wherein the combustion unit consists of frame (16) bonded to a boiler main body, etc. and, supported thereby via heat insulators (15a,15b,15c), ceramic combustion tube (14) with its one end communicating with the distal end portion of the venturi tube type mixer of the fuel supply unit and with its other end protruding into the interior of boiler main body, etc., and wherein the ceramic combustion tube is made of a ceramic functioning as an oxidation catalyst so that compact stable combustion is attained without NOx generation and without unburnt residue.

Description

Combustor

Technical field

[0001]

The present invention relates to a combustor for obtaining high-temperature gas, for example, for a fuel reformer of a small fuel cell system for home use. Background art

[0002]

It is desirable that the combustion gas generated from this type of combustor should be free of pollutants, that is, NOx and unburned matter, and have a low residual oxygen content due to complete combustion.

[0003]

Conventionally, in this type of combustor, (1) Air and fuel are mixed at a concentration within the explosion limit range, and this mixed gas is ignited by an ignition means such as an electric spark to form a flame. After that, a combustor that continuously burns the above-mentioned mixed gas of air and fuel. (2) A preheated mixed gas obtained by mixing fuel in preheated air is burned by a combustion catalyst. (3) The outside of the heating tube of the main combustor is always heated above the ignition temperature of the fuel by the auxiliary combustor. In the main combustor, a mixed gas of fuel and air is brought into contact with the heated heating tube. 1: Combustor designed to continue combustion. (4) A U-turn is made at the end of the tube to burn the combustion gas that is burned by bringing the mixed gas of fuel and air into contact with the tube heated above the ignition temperature of the fuel. The combustor is designed to continue combustion by heating the pipe. (Japanese Patent Laid-Open No. 10-2 6 3 0 9) and the like are known.

[0004]

In the conventional combustor described above, small household fuel cells that are currently being developed It is not satisfactory as a boiler combustor for use in a system fuel reformer.

[0005]

The reason for this is that the combustor used in this type of device is required to be small and have a small combustion chamber volume, and the temperature of the surrounding wall surface is about 110 to 180 ° C. Because it is necessary to have a low temperature, complete combustion with a low NOX concentration is required, even though the conditions are very disadvantageous to combustion.

[0006]

Furthermore, the small volume of the combustion chamber means that it is susceptible to pressure fluctuations. In the case of flame combustion, the fuel flow temporarily stops due to pressure fluctuations, the flame disappears, and combustion stops. However, steam generation may cease.

[0007]

For this reason, the ratio of S Z C (steam / carbon) becomes lower than the appropriate value in the reforming catalyst section, carbon deposition occurs, and the entire fuel reformer stops.

[0008]

Furthermore, the use of gaseous fuel and liquid fuel is required in the above-mentioned small-sized home fuel cell system. At the start of operation, an auxiliary igniter must be used, but after the start of operation, this auxiliary combustor is made unnecessary in as short a time as possible, and combustion stops even if there is a disturbance such as pressure fluctuation. It is necessary to adopt no method.

[0009]

The present invention has been made in view of the above, and it is possible to obtain a compact combustion gas that is free from the generation of NOX as a pollutant and does not remain unburned, and that is stable even with a slight disturbance. The purpose is to provide a combustor that can To do.

Disclosure of the invention

[0010]

The first invention is a combustor in which a ceramic combustion cylinder having an oxidation catalyst function is disposed downstream of a bench-lily single-tube fuel / air mixer equipped with an igniter.

[0011]

The second invention is a combustor according to the first invention, wherein a vortex generator is provided at the tip of a bench-lily single-tube type fuel 'air mixer so that the mixture becomes a vortex in the ceramic combustion cylinder. is there.

[0012]

According to a third invention, in the first or second invention, the downstream end portion of the ceramic combustion cylinder is covered with a cylindrical cover whose head is closed, and a combustion chamber is further provided around the tip of the ceramic combustion cylinder. It is a combustor formed and provided with a combustion gas outflow hole at the cylindrical base end of the cover.

[0013]

A fourth invention is the combustor according to the third invention, wherein a radiation promoting paint is applied to the outer peripheral surface of the cover.

[0014]

A fifth invention is the combustor according to the third or fourth invention, wherein an oxidation catalyst layer is provided between the ceramic combustion cylinder and the base end portion of the cover.

[0015]

According to the first invention, for example, it has a small combustion chamber suitable as a combustor for a boiler used in a fuel reformer of a small-sized domestic fuel cell system that is currently being developed. Combustion efficiency is good and stable combustion is possible A simple combustor can be obtained.

[0016]

According to the second invention, since the air-fuel mixture sufficiently corrodes the oxidation catalyst, a combustor capable of more stable combustion can be obtained.

[0017]

According to the third invention, combustion of the combustion gas flowing out from the ceramic combustion cylinder is further promoted in the combustion chamber constituted by the cover.

[0018]

According to the fourth aspect of the invention, since the radiant heat can be radiated from the outer surface of the cover to the heated part, the heating of the heated part can be promoted.

[0019]

According to the fifth aspect of the invention, since the combustion gas flowing out from the combustion chamber in the cover through the through hole passes through the catalyst layer having an oxidation function, it is assumed that the combustion gas burned in the ceramic combustion cylinder is unburned in the combustion gas. Even if a minute remains, the unburned component can be completely burned while passing through the catalyst layer. Brief Description of Drawings

[0020]

FIG. 1 is a cross-sectional view showing a main part of a first embodiment of a combustor according to the present invention.

FIG. 2 is a cross-sectional view showing an embodiment of a boiler in which the combustor of the first embodiment of FIG. 1 is used.

FIG. 3 is a cross-sectional view showing a second embodiment of a combustor according to the present invention and another embodiment of a boiler provided with the same. BEST MODE FOR CARRYING OUT THE INVENTION

[0021]

A first embodiment of the present invention will be described with reference to FIG. 1 and FIG. FIG. 1 is a cross-sectional view showing the main part of the combustor of the present invention, and FIG. 2 is a cross-sectional view showing an example of a boiler using the combustor of the present invention.

[0022]

In FIG. 1, 1 is a boiler body composed of an inner cylinder 2 and an outer cylinder 3 arranged concentrically, and 4 is a combustor according to the present invention provided at the lower end of the boiler body 1. The high temperature combustion gas generated in the combustor 4 is supplied to the inner surface of the inner cylinder 2 of the boiler body 1 so that the inner surface of the inner cylinder 2 is heated, and the inner cylinder 2 arranged concentrically with the outer cylinder 2 The water (evaporation medium) supplied in the heat medium jacket 5 formed between the cylinders 3 is heated to generate high-temperature steam. A boiler lower flange 6 that closes the heating medium jacket 5 for the evaporation medium is coupled to the lower end of the boiler body 1. By connecting the flange 7 with the bolt 8 and the nut 9, the combustor 4 is located at the lower end of the boiler body 1 and the cover 10 located at the top of the combustor 4 is located in the inner cylinder 2 of the boiler body 1. It is designed to be joined in the state of rushing into.

[0023]

The combustor 4 includes a combustion unit 11 including a ceramic combustion cylinder 14 from which the combustion gas is ejected, and a fuel supply unit 1 2 for supplying a fuel Z air mixture obtained by mixing fuel and air to the combustion unit 11. It is made up of.

Combustion section 11 is located at the uppermost position and has a combustion chamber forming cover 10 that forms combustion chamber 13 inside, and is disposed at the axial center of the cover, and the upper end is opened into combustion chamber 13. The released ceramic combustion cylinder 14 and the outside of the bottom of this ceramic combustion cylinder It is composed of heat insulators 15 5 a, 15 b, 15 c, and a frame 16 surrounding these heat insulators. Is fixed to the combustor flange 7.

[0024]

The cover 10 has a bell shape (or a tea tube cap shape), and is provided in a state of covering the heat insulators 15 a, 15 b, and 15 c. A slit-like through hole (combustion gas outflow hole) 17 that is long in the vertical direction is provided at the end. Inside the cover 10, a catalyst layer 18 made of ceramic small particles having an oxidation function is provided at the height of the through hole 17. The upper end of the ceramic combustion cylinder 14 has a predetermined distance L between the upper surface of the catalyst layer 18 and the upper surface of the catalyst layer 18 in the combustion chamber 13 天井 with a predetermined distance L from the ceiling inner surface of the cover 10. Combustion gas that has H and flows out from the upper end of the ceramic combustion cylinder 14 flows from the combustion chamber 1 3 through the catalyst layer 1 8 through the through hole 1 7 into the inner cylinder 2 of the boiler body 1. It ’s like that.

[0025]

The fuel supply unit 12 is fixed to the lower surface of the combustion unit 11 via a packing via a mounting flange 21 provided at the upper end portion thereof via a packing.

A Venturi tube type mixer 23 is fixed to the mounting flange 21 so as to penetrate therethrough. The outlet portion of the bench lily single-tube mixer 2 3 is concentric with the ceramic combustion cylinder 14 of the combustion section 11 1 and its outlet diameter is substantially the same as the inner diameter of the ceramic combustion cylinder 14. The outlet end of this is in contact with the lower end of the ceramic combustion cylinder 14. A vortex generator 24 is provided at the contact portion. This eddy current generator 24 directs the mixed air flow from the bench lily single tube mixer 2 3 in the circumferential direction, that is, ceramic fuel. It has a shape that generates a vortex along the inner peripheral surface of the firing tube 14

[0026]

A plurality of fuel injection holes 25 are provided on the circumferential surface of the throat portion of the bench lily single tube mixer 23. The fuel injection hole 25 is connected to the fuel supply port 26 via a fuel handle 25 a provided in the throat portion of the bench lily single pipe mixer 23.

An igniter ignition rod conduit 27 is provided at the axial center of the venturi-type mixer 23. The ignition rod conduit 27 has an upper end fixed to the center of the vortex generator 24 and a lower end projecting downward from the venturi-type mixer 23. An ignition rod 28 is inserted into the ignition rod conduit 27 so that its tip protrudes from the ignition rod conduit 27.

[0027]

A cross-shaped pipe fitting 29 is connected to the base end of the Venturi tube mixer 23, and the lower end of the ignition rod conduit 27 is positioned within the pipe fitting 29. Yes. And one of the two connection ports in the direction orthogonal to the extension line of the connection port of the pipe joint 29 to the bench lily one-pipe mixer 23 is an igniter power rod connection port, A power rod 30 for the igniter is inserted from the end, and the tip thereof is electrically connected to the ignition rod 28 in the connection pipe 29. A combustion air supply port 3 1 is connected to the other of the two connection ports. Furthermore, a combustion state monitoring port 3 2 that allows the inside of the venturi single-pipe mixer 2 3 to be seen through is connected to the connection port on the extension line of the connection port of the pipe joint 28 with the bench lily single-pipe mixer 2 3. Yes.

[0028]

The operation of the combustor 4 on the boiler body 1 shown in Fig. 1 is described below. The

[0029]

Combustion air is supplied from the air supply port 3 1 of the fuel supply unit 1 2, and the fuel supplied from the fuel supply port 2 6 is supplied to the throat portion of the venturi single-tube mixer 2 3 from the fuel injection port 2 5. By blowing out, this air and fuel are mixed from this slot to the outlet of the venturi single-pipe mixer 23 to form a fuel / air mixture (hereinafter referred to as a mixture). It flows into the ceramic combustion cylinder 14 from the outlet of the mold mixer 2 3. At this time, the air-fuel mixture flowing into the ceramic combustion cylinder 14 becomes a vortex along the inner peripheral surface of the ceramic combustion cylinder 14 by the vortex generator 24. In this state, the igniter power rod 30 is energized to form a spark at the tip of the ignition rod 28 to ignite the mixture.

[0030]

As a result, the air-fuel mixture starts to burn. After ignition, it is influenced by the mixture ratio of fuel and air in the mixture, but even if the spark is stopped within 2 minutes, the ceramic combustion cylinder 14 is heated above the temperature at which it functions as an oxidation catalyst. If so, the combustion will continue.

[0031]

When liquid fuel (such as kerosene) is used for the above combustion, the fuel itself is supplied at room temperature, but the combustion air is supplied preheated to about 2 ° 0 to 25 ° C. In the configuration of this embodiment, gaseous fuel can also be used.

[0032]

The ignited air-fuel mixture starts to combust, and the combustion gas flows upward along the inner peripheral wall of the ceramic combustion cylinder 14. As a result, the ceramic combustion cylinder 14 itself is heated to a temperature higher than the catalyst activation temperature. This result As a result, even when the ignition by the ignition rod 28 was stopped when the ceramic combustion cylinder 14 was heated, the mixture from the bench-lily single-tube mixer 23 was raised to the catalyst activation temperature or higher. By contacting the inner peripheral surface of the ceramic combustion cylinder 14, an oxidation reaction immediately occurs in this air-fuel mixture, and combustion continues.

[0033]

Such combustion becomes intense as it goes upward (downstream) of the ceramic combustion cylinder 14, and most of the air-fuel mixture is combusted at the upper end of the ceramic combustion cylinder 14. The combustion state at this time is affected by the length of the ceramic combustion cylinder 14. For this reason, the length of the ceramic combustion cylinder 14 is designed such that most of the air-fuel mixture supplied from the fuel supply section 12 is combusted.

[0034]

Since the air-fuel mixture supplied to the ceramic combustion cylinder 14 is mixed at a uniform concentration, the combustion reaction in the ceramic combustion cylinder 14 is very fast. For example, when the theoretical combustion temperature of the air-fuel mixture is about 1400 to 1600 ° C., it indicates a combustion speed of about 7 to 100 seconds. Therefore, it is desirable that the material of the ceramic combustion cylinder 14 has the following properties.

[0035]

That is, the necessary conditions for the above-mentioned ceramic combustion cylinder 14 having an oxidation function are: (1) strong thermal shock resistance, (2) low catalyst activation temperature, (3) high emissivity, (4) High mechanical strength at high temperature, (5) High heat conductivity.

[0036]

The ceramics having such _{properties, S i C, S i 3} N 4, Z r 0 2 and Z r O. To which 5 to 20% of other metal oxides are added Is suitable.

[0037]

S i C, S i ₃ N ₄ S i non-oxide ceramics have a catalytic activity temperature of 640 to 6 45 ° C, but other than this, the above conditions are satisfied. It is. In addition, Zr 0 ₂ alone has a catalyst activation temperature of 4 65 ° C, but C o O, C r ₂ 0 ₃ , Mn0 ₂ , La ₂ O ₃ , S n0 ₂ , Ύ ₂ O ₃ , T b O ₂及Pi M g O a mixture from 5% to 20% is capable of decreasing the catalytic activity temperature from 3 3 0 to 4 9 7 ° about C (9th Symposium on catalytic combustion (See “Catalytic Combustion with Zr 0 ₂ Composite Oxide” published on May 25, 1990).

[0038]

The reason why the thermal shock resistance (1) described above is required to be strong is that the amount of heat received from the inside of the ceramic combustion cylinder 14 is large because the combustion speed is high. That is, if the change in the amount of heat received by the ceramic combustion cylinder 14 is large, the temperature change of the ceramic combustion cylinder 14 itself is large, and if the thickness of the ceramic combustion cylinder 14 is increased, the temperature difference inside the ceramic combustion cylinder 14 is large. This is because the ceramic combustion cylinder 14 is destroyed by thermal shock. In order to prevent this, the thermal conductivity of (5) is required to be high. In addition, the high thermal conductivity is suitable for transferring the heat received on the downstream side of the combustion gas to the upstream side, and the high emissivity of (3) exhibits the same effect.

[0039]

Combustion gas generated in the ceramic combustion cylinder 14 flows into the combustion chamber 13 from the tip of the ceramic combustion cylinder 14 and moves downward along the inner surface of the cover 10 constituting this combustion chamber 13. Change the boiler through catalyst hole 1 8 through hole 1 7 It flows out into the inner cylinder 2 of the main body 1.

[0040]

The combustion gas burned at this time may have insufficient combustion if the volume of the passage through which it passes is small and is surrounded by a cold wall, leaving unburned gas in the combustion gas. However, in this combustion section 11, the combustion gas from the ceramic combustion cylinder 14 flows into the combustion chamber 13, which is a relatively large space formed by the cover 10, and thus burns. Is sufficiently continued to reach a high temperature (1500 to 1700 ° C), and the unburned part of the combustion gas is almost completely combusted.

[0041]

The combustion gas in the combustion chamber 13 changes its flow downward along the inner surface of the cover 10 constituting the combustion chamber 13, passes through the catalyst layer 18, and then passes through the hole 1. 7 flows into the inner cylinder 2 of the boiler body 1 and heats the inner surface of the inner cylinder 2. At this time, the combustion gas comes into contact with the small ceramic particles of the catalyst layer 18 so that the unburned components in the combustion gas are completely burned. The presence of the catalyst layer 18 prevents combustion from stopping due to pressure fluctuations in the fuel and combustion air.

[0042]

The ceramic small particles having an oxidation function constituting the catalyst layer 18 are preferably SiC hollow particles.

[0043]

Regarding the combustor 4 shown in the above embodiment, if the dimensions of each member as an example of a combustor for generating steam in a household fuel cell system are given, the inner diameter of the ceramic combustion cylinder 14 is 20 mm. , The thickness is 2.5 mm, the length is 40 mm, and the inner diameter of the cover 10 is 5 O mm, and the dimension of H shown in FIG. Is 10 mm and the dimension of L is 15 mm.

[0044]

As described above, the combustor shown in FIG. 1 is an example applied to a boiler body 1 for a steam generator of a household fuel cell system, and the heat medium jacket 5 of the boiler body 1 is filled. The generated water is boiled and the generated steam is led out from the steam pipe connected to the top of the heat medium jacket 5. In this case, in order to use the cover 10 for a long period of time, it is necessary to transfer the heat received from the high-temperature gas to the heat medium jacket 5 as much as possible. In this embodiment, the cover made of steel is used. Applying a radiation-promoting paint, such as a radiation paint with an emissivity of 92% or more, to the outer peripheral surface of 10 generates combustion gas with a theoretical combustion temperature of 1600 ° C in the combustion section 1 1 Even so, the temperature of the wall of the cover 10 can be 9500 ° C or less, so that the cover 10 can withstand long-term use by applying this radiation promoting paint. It becomes.

[0045]

FIG. 2 shows an embodiment of a boiler using the combustor 4 according to the present invention. A large number of water pipes 3 3, 3 3 are disposed in the inner cylinder 2 of the boiler body 1 and above the combustion section 11. It has a configuration in which a heat exchanging part 3 4 comprising: An exhaust pipe 40 is connected to the inside of the inner cylinder 2.

A water receiving tank 3 5 is provided above the heat exchanging section 3 4, and a water supply pipe 3 6 is connected to the water receiving tank 3 5. The inlet 3 3 a of each water pipe 3 3 of the heat exchange section 3 4 is connected to the water receiving tank 3 5, and the outlet is connected to the outlet chamber 3 7. The outlet chamber 37 is a space formed between the upper part of the support plate 39 supporting the heat exchanging part 34 and the bottom of the water receiving tank 35, and the air is discharged from the heat medium jacket 5 of the boiler body 1. What has evaporated in the liquid-mixed state and what has evaporated in the gas-liquid mixed state from the outlet of the heat exchange section 34 The gas and liquid are separated in the outlet chamber 37. Since the outlet chamber 37 is communicated with the lower part of the heat medium jacket 5 through the conduit 38, the separated liquid medium (hot water) absorbs heat for circulating and evaporating. On the other hand, the vapor of the gas-liquid mixture from which most of the liquid has been separated rises in the space between the inner tube 2 of the boiler body 1 and the outer cylinder part of the water receiving tank 35, and in the upper part of the water receiving tank 35. Gas-liquid separation is performed, and the separated steam is taken out from the steam outlet pipe 41, and the separated hot water is collected in the water receiving tank 35.

[0046]

In such a boiler, the heat of the combustion gas flowing into the inner cylinder 2 of the boiler body 1 from the combustion section 1 1 of the combustor 4 directly acts on the heat medium jacket 5 from the inner surface of the inner cylinder 2 and heat The heat exchanged in the exchanging part 34 can also preheat the water supplied to the heat medium jacket 5 and can effectively use the heat of the combustion gas generated in the combusting part 11.

[0047]

In the above embodiment, by appropriately making the length of the ceramic combustion cylinder 14 in the combustion section 11 of the combustor 4, the fuel supply section 1 2 is supplied from the venturi one-pipe mixer 2 3 alone. When the burned air-fuel mixture can be burned to a state where there is almost no unburned portion, the cover 10 for constituting the combustion chamber 13 can be omitted (the cover 10 is omitted). Examples will be described later).

[0048]

Further, even when the cover 10 is provided, if the combustion in the combustion chamber configured in the cover 10 is performed and the unburned components in the combustion gas are completely burned. The catalyst layer 18 inserted so as to close the through hole 17 of the cover 10 may be omitted. [0049]

In the above embodiment, the cover 10 is disposed on the outlet side of the ceramic combustion cylinder 14. However, as described above, in the combustion section 11 of the combustor 4, the ceramic combustion cylinder 14 If the air-fuel mixture supplied from the venturi-type mixer 2 3 of the fuel supply unit 1 2 can be combusted to a state where there is almost no unburned fuel by appropriately adjusting the length, The cover 10 for constituting the combustion chamber 13 can be omitted. This is shown in FIG. 3 as a second embodiment. In the second embodiment shown in FIG. 3, the outlet side of the ceramic combustion cylinder 14 is provided with a large number of guide passages 19 for deriving the combustion gas from the ceramic combustion cylinder 14 radially outward. It is closed with 15 d of insulation. The combustion gas led out of the heat insulator 15 d in the outer circumferential direction is discharged in the upper part of FIG. 3, and a number of vertical descending water pipes 4 are placed in the space between the inner cylinder 2 and the outer cylinder 3. The inner cylinder 2 of the boiler main body 1 in which 2 is arranged at intervals in the circumferential direction and the outer walls of a large number of water pipes 33 arranged in the central region of the boiler main body 1 are heated.

[0050]

In the second embodiment shown in FIG. 3, unlike the first embodiment shown in FIG. 1, the combustion section 11 cannot be expected to reach a temperature at which the ceramic combustion cylinder 14 functions as an oxidation catalyst. In the upstream region, the ceramic combustion cylinder 14 is omitted, and instead, in the omitted part, the heat insulator 15 a forms a combustion path having the same diameter as the inner diameter of the ceramic combustion cylinder 14. Such a structure is advantageous in terms of cost because it can save the material cost of the ceramic combustion cylinder. This structure can also be used for heating a reformer or for starting a fuel cell using a solid oxide.

Claims

The scope of the claims

1. A combustor characterized in that a ceramic combustion cylinder having an oxidation catalyst function is arranged downstream of a bench lily single pipe type fuel / air mixer equipped with an igniter.

2. The combustor according to claim 1, wherein a vortex generator is provided at the tip of the bench lily single pipe type fuel / air mixer so that the air-fuel mixture becomes a vortex in the ceramic combustion cylinder.

3. The downstream end of the ceramic combustion cylinder is covered with a cylindrical cover with the head closed, and a further combustion chamber is formed around the tip of the ceramic combustion cylinder. At the cylindrical base end of the cover The combustor according to claim 1 or 2, further comprising a combustion gas outflow hole.

4. The combustor according to claim 3, wherein a radiation promoting paint is applied to the outer peripheral surface of the cover.

5. The combustor according to claim 3, wherein an oxidation catalyst layer is provided between the ceramic combustion cylinder and the base end of the cover.