JPH04350419A - Catalyst combustion device - Google Patents

Abstract

PURPOSE:To increase an amount of radiation calorie by a method wherein a red-heated part of catalyst pellets is expanded in the flowing direction in proportion to an amount of combustion, a combustion state can be confirmed with view through a heat-resistant glass cylinder and the radiation heat from a side surface of the catalyst pellets is reflected by a reflection plate through the heat-resistant glass cylinder. CONSTITUTION:A catalyst combustion device is constructed such that a proper number of catalyst combustion cylinders 1A are vertically installed, their lower portions are supported by a diffuser chamber 2A. Their upper portions are similarly supported by an air discharging duct 6A. In turn, fuel and combustion chamber air are mixed to each other at a mixing chamber (not shown) at a lower part of the diffuser chamber 2A so as to produce pre-mixed gas. The catalyst combustion cylinder 1A is constructed such that a pre-heating heater 13A is disposed at the most-upstream side of an inlet port in the cylindrical heat-resistant glass cylinder 12A and a proper number of catalyst pellets 11A are arranged in sequence at an upper down-stream side of the pre-heating heater. With such an arrangement, the red-heated portions of the catalyst pellets 11A are expanded in the flowing direction in proportion to the amount of combustion, thereby the combustion state can be confirmed conveniently with view through the heat-resistant glass cylinder 12A.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a catalytic combustion device that applies an oxidation catalyst with excellent far-infrared radiation efficiency and is used for heating, drying, etc.

[Prior Art] A catalytic combustion device that mixes gaseous fuel and vaporized liquid fuel with air, sends it to a catalyst layer, contacts the catalyst, and burns it flamelessly on the surface of the catalyst layer does not emit nitrogen oxides. Since it has excellent features such as realizing mild radiant heating by the effect of far infrared rays emitted from the catalyst layer, various proposals have been made in the past, and some have been put into practical use.

Conventionally, among such catalytic combustion devices, as an example of one that uses a heat-resistant inorganic material as a carrier and utilizes radiant heat generated from a catalyst layer, the applicant has proposed a device shown in FIGS. 3(a) and 3(b).
There is a catalytic combustion device with the structure shown in ). Figure 3 (a
), (b), 1 is the catalyst layer, 10 is 1
Next air adjustment hole, 11 is a preheating burner, 12 is a vaporizer, 1
3 is a secondary air hole, 15 is a blower, 23 is an ignition heater,
25 is a temperature sensor. In this way, a single plate of the catalyst layer 1 having a relatively large area is erected vertically so that the premixed gas passes from the rear to the front of the catalyst layer, and at the same time the blower 15 is operated, a preheating burner is installed from the back of the catalyst layer. 11 is ignited by the ignition heater 23 to perform flame combustion, the catalyst layer 1 is heated with this combustion heat, and when the catalyst layer reaches the ignition temperature (activation temperature) or higher, the flame of the preheating burner is extinguished. , a structure in which a premixed gas formed by mixing vaporized kerosene, primary air from the primary air adjustment hole 10, and secondary air from the secondary air hole 13 is immediately supplied to the catalyst layer 1 to start catalytic combustion. It has become. At this time, the wide exit surface of the catalyst layer is utilized for radiation.

[Problems to be Solved by the Invention] The conventional catalytic combustion device described above has the following drawbacks.

Normally, for the same volume of catalyst layer, if the amount of combustion is reduced while keeping the air ratio constant and the surface load, which is the amount of combustion load per unit area of the catalyst, is reduced, the combustion temperature of the catalyst layer is lowered.

Furthermore, if only the amount of combustion is reduced while the amount of combustion air is kept constant, the combustion temperature of the catalyst layer will drop even more rapidly. That is, the catalyst layer burns in a red-hot state at the maximum combustion amount, whereas the catalyst layer does not reach a red-hot state at the lowest combustion amount, and burns with an appearance similar to that at room temperature. At such a minimum combustion amount, it is difficult for the user to easily visually recognize whether or not the combustion state is present, which tends to make the user feel uneasy, and the visual effect is poor.

Conventionally, in order to make the catalyst layer red-hot even at the lowest combustion rate, it was necessary to reduce the loaded area of the catalyst layer and at the same time increase the thickness in the flow direction of the premixed gas to increase the surface load. However, in the case of such a method, the load area of the exit surface, which is the radiation utilization surface, is small, resulting in a disadvantage that the amount of radiant heat is small.

In addition, in the case of the conventional structure, the load area of the catalyst layer is large, making it difficult to heat it uniformly during preheating operation, and when the premixed gas is sent to start catalytic combustion, unburned gas is discharged from the lower temperature part. It's easy to do.

[Means for Solving the Problems] The catalytic combustion device according to the present invention has been made to solve the above problems, and uses a small-volume cylindrical or prismatic cross-section with excellent air permeability, such as a honeycomb. A plurality of shaped catalyst pellets are inserted into a heat-resistant glass tube, and a resistive heat-generating inorganic material molded into a shape with excellent air permeability, such as a honeycomb, is inserted at the bottom of the catalyst pellet along with an electrode to perform catalytic combustion. One or more of these catalytic combustion tubes are erected to form a flow path to supply premixed gas from the bottom, and infrared rays emitted from the catalyst pellets are passed through heat-resistant glass behind the catalytic combustion tube. A reflector plate is installed on the front side to reflect the light.

[Function] In the above configuration, during the preheating operation of the catalyst layer, the resistance-generating inorganic material at the bottom of the catalyst combustion cylinder is energized to generate heat, thereby causing the catalyst pellets disposed on the top to undergo heat conduction and natural convection. Preheating can be performed efficiently by heat transfer, and preheating can be completed quickly. Furthermore, since the load area of one catalytic combustion cylinder is small, heat uniformity in the cross section of the catalyst is also good, and steady combustion can be reliably achieved without emitting unburned gas.

During steady combustion, the load area of the catalyst layer is smaller than in the case of the conventional structure, so even when the combustion amount is small, the catalyst pellet inlet can be kept in a red-hot state, and this red-hot area is heated upward in proportion to the combustion amount. This allows the user to easily recognize the combustion status by visual inspection through the heat-resistant glass, regardless of the amount of combustion. At the same time, the infrared rays emitted from the sides of the catalyst pellets, which have become hot due to combustion, pass through the heat-resistant glass cylinder and are reflected forward by the reflector, allowing for comfortable radiant heating with a large radiant area. In addition, since it is composed of an aggregate of small catalyst pellets and a resistance heating inorganic material for preheating, individual molding is easy and costs are reduced.

[Example] An example of the present invention will be described below based on FIGS. 1 and 2.

In the catalytic combustion apparatus according to the present invention, as shown in FIGS. 1 and 2, 1A is a catalytic combustion tube, and one or more of the catalytic combustion tubes stand vertically. 2A is a diffuser chamber, which is a box-shaped chamber that firmly supports the catalytic combustion tube 1 from below and evenly supplies the premixed gas sent from the bottom opening to the ceiling opening communicating with the catalytic combustion tube. Reference numeral 3A denotes a mixing chamber, which mixes fuel sent through an oil feed pipe 4A from an oil feed pump (not shown) with combustion air fed under pressure from a blower 5A to generate a premixed gas. Incidentally, when the fuel is liquid fuel, a heater for vaporizing the fuel is installed in the mixing chamber 3A. 6A is an exhaust duct and catalytic combustion tube 1
It is a box-shaped chamber that firmly supports A at the top, collects combustion gas sent from the bottom opening communicating with the catalytic combustion cylinder, and discharges it into the atmosphere from the top opening. The catalytic combustion tube 1A mainly includes a cylindrical heat-resistant glass tube 12A with excellent heat transmittance, and a heat-resistant material such as cordierite molded into a shape with excellent air permeability such as a cylindrical or prismatic cross section with a honeycomb structure. Several catalyst pellets 11A made of an inorganic material used as a carrier and supporting an oxidation catalyst such as a platinum group metal on the surface thereof, and a preheating heater 13A having the same shape as the catalyst pellets and molded from a resistance-generating inorganic material such as silicon carbide. A preheating heater 1 is installed at the most upstream part on the inlet side in a heat-resistant glass cylinder 12A.
3A also has several catalyst pellets 11 on its upper downstream side.
A is stacked and inserted. Electrodes for applying voltage are attached to two locations on the outer periphery of the preheating heater 13A, and the lower end of the electrode is insulated and maintained by an insulating sealant at a connection portion to the diffuser chamber 2A. 16A is a temperature sensor, which is attached to the top of each catalytic combustion cylinder. 7A is a guard net that surrounds the catalytic combustion cylinder 1 which becomes hot during operation to ensure safety.

8A is a reflector, which is installed in the catalytic combustion tube 1 in the cabinet 9A.
It is arranged so as to surround the back of A. 10A is a hot air outlet located on the ceiling of cabinet 9, and exhaust duct 6A
The hot air discharged from the is discharged upward.

The operations of the catalytic combustion device having the above configuration include a preheating operation in which the catalyst layer is heated above the ignition temperature prior to catalytic combustion, and a premixed gas of a fixed amount of combustion is sent to the catalyst layer that has reached the ignition temperature to perform catalytic combustion. It consists of a steady combustion operation in which premixed gas of an arbitrary combustion amount is flamelessly combusted within the catalyst layer.

In the preheating operation, first, the preheating heater 13A is energized. When energized, the preheating heater generates heat, and heat is transferred from the catalyst pellet directly above it to the catalyst pellets above it by heat conduction and natural convection. In this way, when a control unit (not shown) determines based on the outputs of the temperature sensors 16A that the catalyst pellet temperature has reached the ignition temperature (for example, 300° C.) for each of the temperature sensors 16A attached to each catalyst combustion cylinder, The power supply to the preheating heater is stopped, and at the same time, weak air blowing is started by the blower 5A, and fuel supply from the fuel pipe is started to generate premixed gas in the mixing chamber 3A and send it to the diffuser chamber 2A. In the diffuser chamber 2A, the premixed gas uniformly spreads the flow path and is sent to the catalytic combustion cylinder 1A, where it starts catalytic combustion.

That is, the preheating operation is completed and the steady combustion operation is started.

Since the catalyst pellet assembly is designed to have a volume that provides sufficient space velocity to completely burn any amount of premixed gas at the set combustion amount, it does not emit odorous gases such as CO and HC. The process progresses from ignition to temperature rise to steady weak combustion, and the upstream catalyst pellet reaches a red-hot state (650 to 7
The temperature reaches steady state at 50°C). In addition, during steady combustion, the fuel delivery amount and the airflow amount of the blower 5A are controlled, and the volume ratio (i.e., air ratio) of the combustion supply air amount to the theoretical air amount of the premixed gas is always maintained at about 2 to 4, and the catalyst Combustion is performed while preventing backfire and incomplete combustion of the premixed gas by constantly controlling the amount of air blown to be appropriate for the amount of combustion using the temperature sensor 16A so that the maximum temperature of the pellets 11A does not exceed 800 degrees Celsius. The amount can be increased or decreased. At this time, when the combustion amount of the catalyst pellet is low, only a portion near the upstream side becomes red-hot, but as the combustion amount increases, the red-hot portion expands upward. After the completely burned exhaust gas is discharged from the catalyst pellet 11A, it is passed through the exhaust duct 6.
A, and is discharged as hot air from the hot air port 10A. On the other hand, infrared rays are emitted from the catalyst pellets through the heat-resistant glass tube 12A. Therefore, convection heating using warm air and radiant heating using infrared rays are performed simultaneously.

When extinguishing a fire, cut off the power to other equipment except for the blower 5A, and operate only the blower 5A for several tens of seconds to blow air.
Cools the system mainly consisting of the catalytic combustion cylinder. At this time, the catalyst pellets have a relatively large heat capacity, so even if the supply of premixed gas is abruptly cut off, odorous gases such as CO and HC will not be emitted for a while after extinguishing, unlike in normal combustion with flames. , completely oxidized on the catalyst pellets.

[Effects of the Invention] In the catalytic combustion device according to the present invention, a plurality of small-volume cylindrical or prismatic honeycomb cross-section catalyst pellets are inserted into a heat-resistant glass cylinder, and a honeycomb or the like is further inserted at the bottom of the catalyst pellet. A resistance-generating inorganic material molded into a shape with excellent air permeability is inserted together with an electrode to form a catalytic combustion tube, and one or more of these catalytic combustion tubes are erected and a flow path is formed to supply premixed gas from the bottom. A reflector plate is installed behind the catalytic combustion cylinder to reflect infrared rays emitted from the catalytic pellets to the front through heat-resistant glass. This produces the following effects.

(1) Since the red-hot part of the catalyst pellet expands in the flow direction in proportion to the amount of combustion, the user can easily check the combustion status visually through the heat-resistant glass tube, and does not feel anxious during operation. . Furthermore, since the radiant heat from the side surface of the catalyst pellet is reflected forward by the reflector through the heat-resistant glass tube, a large amount of radiant heat can be obtained.

(2) During preheating of the catalyst layer, electricity is applied to the resistance-generating inorganic material at the bottom of the catalytic combustion cylinder to generate heat, thereby efficiently preheating the catalyst pellets disposed above it through heat conduction and natural convection heat transfer. Preheating can be completed quickly. In addition, since the area of the catalyst layer to be preheated is small,
It is easy to equalize heat in the cross section of the catalyst pellet during preheating, and it is possible to reliably shift to steady combustion without emitting unburned gas.

(3) Since it is composed of an aggregate of small catalyst pellets and a resistance heating inorganic material for preheating, individual molding is easy and costs are low.

[Brief explanation of drawings]

FIG. 1 is an overall view showing one embodiment of the present invention, and FIG. 2 is a sectional view of a catalytic combustion tube. FIGS. 3(a) and 3(b) show a conventional example, and are a plan view and a side view. 1A is a catalytic combustion tube, 3A is a mixing chamber, 5A is a blower, 10
A is a hot air port, 11A is a catalyst pellet, 12A is a heat-resistant glass, 13A is a preheating heater, and 16A is a temperature sensor. Agent: Patent attorney Masaru Umeda (and 2 others)

Claims (2)

[Claims] Claim 1: In a catalytic combustion device that mixes gaseous fuel or vaporized liquid fuel with combustion air to form a premixed gas and sends it to a catalyst layer for flameless combustion, an oxidizer with excellent air permeability such as a honeycomb is used. Catalyst pellets are formed by molding the catalyst layer into small cylinders or squares, and one or more catalytic combustion cylinders are constructed by inserting multiple catalyst pellets into a heat-resistant glass cylinder with excellent heat permeability. A flow path is configured so that the premixed gas passes through the lever from below, and a reflecting plate is placed behind the catalyst combustion tube to reflect the radiant heat from the side surface of the catalyst pellet forward through the heat-resistant glass tube. catalytic combustion equipment. 2. A resistive heat-generating inorganic material, which has the same external shape as the catalyst pellet and is molded into a highly breathable cross-sectional shape such as a honeycomb, is arranged as a preheating heater under the catalyst pellet in the catalyst combustion cylinder. A catalytic combustion device according to claim 1.