JPS60221608A - Method of operating fluidized-bed furnace - Google Patents

Abstract

PURPOSE:To make a starting operation in a fluidized-bed furnace easy, by mixing to coexist catalyst particles which are effective to promote combustion of fuel with fluidized medium particles. CONSTITUTION:Combustion catalyst particles to lower the temperature to ignit fuel are mixed with fluidized medium particles. Following can be used as catalyst contents: metallic catalyst contents such as Pt, Pd; metallic mixture catalyst contents such as Pt+Pd, Pt+Rh; catalyst contents of oxide or mixture of those oxides such as Co, Cu, Mn, Cr, Ni, Fe; mixed catalyst contents of metal and oxide such as Pt+Co3O4, Pt+ThO2.CoO2; complex oxide catalyst contents such as LaCoO3, LaMnO3, CuCrO4, CoAl2O4. A catalyst consists of a carrier such as gamma-Al2O3, ZrO2, TiO2 carrying the above-mentioned catalyst contents. With such an arrangement, a starting operation can easily be performed in the titled furnace.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to improvements in operating methods of various fluidized bed heating furnaces and incinerators.

(Summary of Prior Art) In recent years, improvements have been made in recent years to improve the many properties of fluidized beds, such as high heat transfer performance, temperature uniformity based on mixability, and operational stability due to the large heat capacity of fluidized bed particles. The application of fluidized beds to various industrial equipment has become extremely active.

That is, a fluidized bed apparatus generally maintains a uniform bed temperature and easily controls it within a constant temperature range, and is very advantageous for application to reaction systems and heat treatment systems where setting of temperature conditions is important. In addition, when the purpose is incineration or chemical reaction,
This method has the advantage that it can be easily applied to the treatment of products with complex physical properties or properties that are likely to cause fusion granulation, or products where the supply of reaction heat is not constant and tends to fluctuate.

From this point of view, fluidized beds have recently been increasingly used, especially at high temperatures of about 600 to 100°C.

Normally, in order for a fluidized bed apparatus to reach these high-temperature operating conditions, the furnace (fluidized bed) from which the fluidized medium has been extracted in a cold state is heated with a startup bar T, and as the temperature of the furnace rises, the fluidized bed is gradually heated up. Generally, the fluidized bed is charged into the furnace until the entire fluidized bed reaches the ignition temperature of the fuel used, and then the specified fuel or fuel such as incineration material is started and steady operation is started. (In some cases, the fluidized medium left in the furnace may be heated up with a flame using a heating burner installed in the middle of the furnace, allowing the blower to operate without completely removing the fluidized medium from the furnace.) , as the temperature rises, fluidizing air is occasionally introduced into the stationary medium bed and rotated to accelerate the overall temperature rise). (Requires a long time, approximately 8 hours to half a day)
This caused a decrease in the actual operating efficiency of the device, and was a major drawback in practical use of the fluidized bed device.

Similarly, when raising the temperature of a fluidized bed device used at high temperatures, high-temperature gas may be used as the fluidizing gas (for example, high-temperature combustion gas from burning fuel is blown into the wind box as fluidizing gas). However, due to the equipment materials and structure, the temperature is at most 600℃.
The limit is to use gas up to a certain temperature, and there are problems with raising the temperature above this. Furthermore, it takes a long time to heat the fluidized bed at such a gas temperature. Therefore, when the temperature exceeds the ignition temperature of the fuel, a method is taken to introduce the fuel into the layer and burn it to increase heating efficiency.Usually, the fuel ignition temperature is 400-550℃ for oil fuel and 550-70℃ for gas fuel.
It is necessary to raise the temperature to about 0° C. by using the method described above.

In the case of solid fuel, it is possible to ignite and raise the temperature at temperatures below 400°C, but this is often inconvenient because combustion residue (ash) remains, so it is rarely used.

FIG. 1 shows an example of a conventionally commonly used fluidized bed apparatus.

This example shows a case where fuel is combusted in a fluidized bed and the combustion heat is transferred to a heat transfer tube and taken out to the outside for use.

A fluidized bed body 1 is filled with a fluidized medium 4, and fluidizing air is sent from a wind box 3 through a fluidized gas dispersion device 2 to fluidize the fluidized medium. At this time, the heat generated by combustion of the fuel introduced into the fluidized bed by the in-bed burner 7 is taken out of the fluidized bed through the heat transfer tube 8 for removing heat from the bed and used.

At startup of this device, the fluidized bed preheating burner 5 or startup burner 6 is used to preliminarily raise the temperature of the fluidized bed device main body 1 and the fluidized medium 4 by the ignition temperature trench of the fuel fed through the in-bed burner 7. It is operated as if it were kept.

In this way, in the operation of a fluidized bed apparatus, it takes time to start up from a normal flow state. In other words, in order to bring the furnace to operating temperature, it is normal to start by raising the temperature of an empty furnace with the fluidized medium taken out of the furnace, and then gradually introduce the fluidized medium and proceed with heating to bring it to the operating state. A major drawback of fluidized bed reactors is that they are difficult to start up quickly.

OBJECTS OF THE INVENTION The present invention overcomes the above-mentioned drawbacks of the conventional methods and facilitates the operation of a fluidized bed reactor, especially during start-up.

(Structure of the present invention) Generally, inert particles such as sand grains are not used as the fluidized medium of a fluidized bed apparatus, but in the present invention, a combustion promoting catalyst that allows fuel to ignite and burn at a lower temperature than usual is added to a part of the fluidized medium particles. This method is new in that it uses a mixture of particles impregnated with The present invention relates to a method of operating a fluidized bed furnace characterized by mixing and coexisting catalyst particles having an effect of promoting combustion of fuel.

(Field of Application of the Present Invention) The present invention can be advantageously applied to various heating, incineration, and reaction devices that utilize a fluidized bed.

(Details of the present invention) As mentioned above, inert particles such as sand and alumina particles are used as fluidized media in fluidized bed furnaces used at high temperatures. It took a very long time to reach this point.

In the present invention, combustion catalyst particles that lower the ignition temperature of the fuel are mixed in the fluidized medium, and the temperature is so low that the fuel cannot be ignited in normal operation. ) to reach the operating temperature.

In the present invention, the catalysts mixed and coexisting in the fluid medium include metal catalyst components such as Pt and Pd, pt-4-pa
, a metal mixture catalyst component such as Pt-4-Rh, Oo.

Oxide such as Ou, Mn, Or, Ni, Fe or mixed oxide catalyst component, P t4-c 0304
, a mixed catalyst component of metal and oxide such as P t-4-'rho2・C002, La(!003゜LaMn01
, 0uCr04, 0OA404, etc., γ-AI403, Zr02. T l
A catalyst supported on a carrier such as 02 is used.

Examples and comparative examples will be given below to clarify the advantages of the present invention.

Comparative Example When conducting a waste incineration test using a fluidized bed with an inner diameter of 500 mm, startup heating of the furnace was performed using LPG.

In the fluidized bed furnace used in the test, the outer surface of the steel shell is wrapped with 50% Kao wool to keep it warm, and the inner surface of the steel shell is covered with a 70-sieve insulating castable.

Approximately 150 kg of olivine sand (foundry sand) with an average diameter of 0.5 m is used as the fluidizing medium.

The startup burner is a bottom burner in which an LPG supply nozzle is installed inside a five cylindrical slit type gas distribution device attached to the bottom of the furnace. When the ν temperature in the startup burner reached 670℃ and air was introduced into the fluidized bed and it was beginning to fluidize, LPG gas was immediately introduced and the gas amount was gradually increased, causing internal pressure fluctuations in the furnace. It started to ignite and burn smoothly with little heat. Next, when the furnace temperature dropped to 620°C, a similar operation was performed, and after a short time it ignited explosively, but this operation was considered dangerous in terms of furnace maintenance. Ignition could not be achieved at a furnace temperature of 600°C.

Example (1) In the same furnace as the comparative example, 40 m of mu
A total of 150 kg of a combustion catalyst consisting of (99.5%)-pt(o, s%) mixed with sand at a mixing ratio of 1:5 (combustion catalyst: sand) was put into the furnace. When the same test as in the comparative example was conducted, even at a furnace temperature of 400°C, smooth ignition was achieved after about 10 minutes after the furnace temperature started to rise. 35
From 0°C, ignition could not be performed even if the air volume was reduced to 50 m3/h.

Example (2) In place of the platinum catalyst in Example 1, A/, 0.　95%.

When the same ignition test as in Example 1 was conducted using a combustion catalyst consisting of 5% copper oxide, smooth ignition was achieved at a furnace temperature of 500°C.

Example (3) When the following catalysts were subjected to the same combustion test as in Example 1, smooth ignition was observed for each catalyst at the furnace temperatures listed.

■ AJ0395 Section Manganese oxide 5% 500℃■
A14d, Section 95 Chromium oxide 5chi 480℃■
At2o398% palladium 2chi 370℃

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a general fluidized bed furnace. Among the sub-agents: 1) Akira Sub-agent Ryo Hagi Hara - Figure 1 1 Izukisu ↑

Claims (1)

[Claims] In a method in which fuel (including incineration materials) is burned in a fluidized bed furnace and the fluidized bed is operated at high temperatures, catalyst particles that have the effect of promoting fuel combustion are mixed and coexisted with fluidized media particles. A method of operating a fluidized bed furnace characterized by the following.