JPS61134515A - Catalytic combustion device - Google Patents

Abstract

PURPOSE:To provide a combustion device of which burning characteristic is superior and having a long life of catalyst by a method wherein gas is supplied under a circulation flow to a mixing container. CONSTITUTION:Circulation vanes 14 for applying circulation flow to either combustion air or combustion gas A are formed around the atomization chamber 12, and an injection nozzle 13 for making liquid fuel in fine particle form is arranged at the central part of the atomization chamber 12. An angle theta in which liquid fuel is injected from the injection nozzle 13 is set such that it may be placed at the downstream side than the central part of the circulation mechanism 14. A cyclone type mixing unit 20 for mixing combustion air or combustion gas and fine particled liquid fuel and gasifying the liquid fuel is provided, a plurality of holes 80 are arranged in tangential with a pipe wall of the sleeve 80 at the central part in such a way as either air or gas may be formed as a circulation flow, and a flow regulation plate 30 may restrict the circulation gas flow of the mixed fluid. Combustion catalyst 41 is arranged in the contact combustion unit 40. With the foregoing, the liquid fuel may sufficiently be gasified before it is reached to the catalyst layer, so that its characteristic of combustion can be improved and at the same time the catalyst layer is not clogged and a decrease in life of the catalyst caused by a partial overheating can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a catalytic combustion device, and particularly to a catalytic combustion device that efficiently burns liquid fuel.

<Conventional technology and its problems> In recent years, the catalytic combustion method using a catalyst enables lower-temperature combustion than normal gas-phase combustion, and reduces nitrogen oxides (hereinafter referred to as "
It has attracted attention because it hardly generates substances such as NOx) and carbon oxide (aO).

Due to these excellent features, the catalytic combustion method has been widely used in off-gas processing in oil refineries and steel mills, in automobile exhaust gas purification, in heating equipment, and in gas turbines as fuel resources diversify and low-pollution combustion is required. It is used for such things. Catalysts used in these combustion processes include noble metals such as platinum, fragilum, and rhodium, or metal oxides such as ferric oxide, cobalt oxide, and nickel oxide. Liquid fuel is increasingly being used in gas fuel ponds because of its cost and ease of handling.

FIG. 3 shows a conventional catalytic combustion device. The device is a liquid fuel tank with 10. Fuel pump 11. Fuel atomization chamber 12:
Mixer 20: rectifier plate 30. Contact combustor 40, heat exchanger 5
0. It consists of an air preheater 6o and a blower 7o. The liquid fuel is pressurized by a fuel pump 11, and then transferred to an atomization chamber 12.
It is atomized by the spray nozzle 13 inside and guided into the mixer 2g. On the other hand, the combustion air is heated in the air preheater 50 and then heated in the atomization chamber 12. The mixture is introduced into the mixer 20. The mixer 20' usually has a circular or rectangular cross-section, and the cross-sectional area increases as it goes downstream, and is connected to the catalytic combustor 4o. The liquid fuel atomized in the atomization chamber 12 is guided to the mixer 20' while swirling together with the combustion air heated by the air preheater 6o, and the liquid fuel is evaporated and mixed with the combustion air. The gas passes through the baffle plate 30 and reaches the catalyst layer 41 in the catalytic combustion device 4°, where it is combusted by the catalytic action and becomes a high-temperature combustion gas, which is then transferred to the heat exchanger 50. It passes through the air preheater 60 and is discharged as exhaust gas. Although not shown here, instead of preheating the combustion air with an air preheater, there is also a method of providing a combustion gas return duct and a blower to return the combustion gas to the atomization chamber to recover waste heat.

By the way, in the mixer 20', it is necessary to quickly mix the atomized liquid fuel and combustion air or combustion gas, and to evaporate the liquid fuel.

Generally, pressure spraying and two-fluid spraying methods are adopted for the spray nozzle 13, but the diameter of the sprayed droplets is not uniform and has a specific distribution, and if the dimensions of the mixture 77520 are inappropriate, the particle size will be large. The droplets fly to the first catalyst layer 41 in the contact combustor 40 without completing their evaporation. When such a phenomenon occurs, the concentration of fuel in the combustion air or combustion gas becomes uneven, and the droplets adhering to the inlet of the catalyst layer 41 are carbonized, resulting in increased flow resistance due to clogging and a decrease in combustion efficiency. This not only causes the generation of unburned substances, but also causes partial overheating of the catalyst, resulting in catalyst burnout.

OBJECTS OF THE INVENTION The present invention was constructed in view of the above-mentioned problems, and provides a combustion device that vaporizes liquid fuel well, prevents local wear and tear of the catalyst, has good combustibility, and has a long catalyst life. Our goal is to provide the following.

Summary of the Means for Purifying Means> In short, the present invention centrifugally separates large-diameter particles of the sprayed liquid fuel by supplying gas as a swirling flow to the mixer to secure time for vaporization, and to provide gas to the catalyst layer. This combustion device is configured to improve combustibility by vaporizing liquid fuel well.

<Embodiment> FIG. 1 shows a first embodiment of the present invention. Reference numeral 14 denotes a swirling vane or a slit-shaped portion that provides a swirling flow to the combustion air or combustion gas A, and is formed around the atomization chamber 12 . A spray nozzle 13 atomizes the liquid fuel, and is provided in the center of the atomization chamber 12.

The angle θ at which liquid fuel is injected from this spray nozzle 13 is
The outer peripheral edge of the dispersed and injected fuel is set to be on the downstream side of the central part of the swirling mechanism 14 such as a swirling vane or a slit. A cyclone type mixer 20 mixes combustion air or combustion gas with atomized liquid fuel and vaporizes the liquid fuel. 80 is a fixed or vertically movable Laval tubular sleeve provided in the center of the mixer 20, and a portion of the combustion air or combustion gas A forms a swirling flow around the pipe wall of the sleeve 80. A plurality of holes 81 are provided tangentially to.

Reference numeral 30 denotes a rectifying plate that suppresses a gas flow in a state where a mixed fluid of combustion air and combustion gas and vaporized liquid fuel forms a swirling flow. 40 is a catalytic combustor, and a combustion catalyst 41 is disposed within the catalytic combustion g34o. Note that reference numeral 90 is a heat insulating material layer covering the outer surface of the device.

Next, the operating state will be described. The liquid fuel a is injected into the atomization chamber 12 by the spray nozzle 13 and atomized.

On the other hand, the combustion air or combustion gas A becomes a strong swirling flow At due to the swirling device 14 such as swirling vanes or tangential slits provided around the atomization chamber 12, and is well mixed into the atomized liquid fuel. do. Due to the strong swirling flow of the liquid fuel introduced into the mixer 20, droplets of coarse particles are separated on the inner wall of the mixer 20, and the separated coarse particles themselves are also vaporized while swirling.

On the other hand, the fine droplets immediately vaporize, and these vaporized liquid fuels are guided into a Laval tubular sleeve 80 provided at the center of the mixer 20. The sleeve 80 is moved upstream or downstream along the center axis of the mixer 20 and the sleeve 80 to adjust the residence time of the separated coarse particle droplets in the mixer 20. Accelerates vaporization of droplets. In other words, sleeve 8
0 to the upstream side, the small-diameter end of the sleeve protrudes into the mixer 20, so the centrifuged large-diameter particles stay on the inner wall surface of the mixer and temporarily return to the upstream side. Then, the particles flow into the small-diameter end of the sleeve, so the overall residence time becomes longer.On the other hand, when the sleeve is moved downstream, the particles flow smoothly and the residence time becomes shorter.

Next, on the peripheral wall of the sleeve 80, a 681 is provided in the tangential direction in the same direction as the swirling direction provided around the atomization chamber 12, and a part of the combustion air or combustion gas is supplied from the 681 to the surrounding wall of the sleeve 80. By ejecting it and creating a swirling flow Ax, vaporization of the liquid fuel and mixing of combustion air or combustion gas are roughly promoted. The vaporized liquid and combustion air or combustion gas are sufficiently mixed to form an air-fuel mixture, which passes through the baffle plate 30 of the catalytic combustor 40 and reaches the catalytic combustion catalyst layer 41. After the air-fuel mixture burns within the catalytic combustion catalyst layer 41, it passes through a thread similar to the conventional device shown in FIG. 3, for example, and is discharged to the outside.

FIG. 2 shows a second embodiment. In this example,
The cone-shaped wall surface of the mixing chamber 20 is formed to have a stepped cross-section to form a stepped portion 21, and the swirling flow is stabilized by the stepped portion, and the heat transfer area of the wall surface is increased to facilitate vaporization of the liquid fuel. Facilitate.

Effects> By carrying out the present invention, liquid fuel can be vaporized well before reaching the catalyst layer, so combustibility can be improved, and the catalyst layer will not be clogged, reducing power costs. In addition, it is possible to prevent the catalyst life from being shortened due to partial overheating of the catalyst.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an embodiment of a catalytic combustion device according to the present invention, FIG. 2 is a sectional view of a mixer showing another embodiment, and FIG. 3 is a system diagram of a conventional catalytic combustion device. 13...Spray nozzle 14.Old...Swivel mechanism 20...Mixer 21...Stepped portion 40...Combustor 8o...・Sleeve 81... Furan Figure 1 Figure 2

Claims (1)

[Claims] 1. In a device that atomizes and vaporizes liquid fuel and then supplies it to a catalyst for combustion, a mixer is located upstream of the combustor, and combustion air is supplied to the mixer. A catalytic combustion apparatus characterized in that a swirling mechanism for swirling and supplying gas such as combustion gas is provided, and a sleeve is interposed between a mixer and a combustor. 2. The catalytic combustion device according to claim 1, wherein the sleeve is configured to be movable in the axial direction of the mixer. 3. The catalytic combustion device according to claim 1 or 2, characterized in that a small hole for forming a swirling flow is formed in the sleeve. 4. The catalytic combustion device according to any one of claims 1 to 3, characterized in that a stepped portion is formed on the inner surface of the cone-shaped wall surface of the mixer.