JPH01150712A - Burner tile of multi-structure - Google Patents

Abstract

PURPOSE:To prevent the generation of cracks in burner tiles in high speed combustion by constituting the title device with an inner cylinder of a thin thickness made of a material which is heat resistant and heat-shock resistant, a middle cylinder on the outer circumference of the inner cylinder which is made of a flexible and heat resistant material, and further an outer cylinder on the outer circumference of the middle cylinder which is made of a material excellent in strength. CONSTITUTION:An inner cylinder 1 consists of a material such as high purity alumina which is resistant to a high load combustion and resistant to heat and heat-shock during ignition and it is relatively thin to make small the thermal stress due to temperature difference. A middle cylinder 2 has flexibility to be able to absorb the thermal expansion of the inner cylinder 1 and made of a material such as ceramic fiber which is excellent in heat insulation. The outer cylinder 3 is made of a material of high strength such as a castable refractory and it holds the shape of total burner tiles, assuring its intallation to the furnace body. With this constitution the tiles develop no crack when it is subject to a high thermal load and no crack will be seen when a strong thermal shock is given to the tiles at the time of ignition.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a burner tile with a multi-layer structure that is installed in combination with a burner in various industrial furnaces.

(Prior art) A burner tile is used to contact and mix fuel injected from a burner and combustion air inside the tile and burn it at a high temperature. As shown, it is integrally formed of a refractory material with a cross-sectional shape that widens toward the discharge port into the furnace. Conventional burner tiles like this one do not pose any problems when used as long as they are made of a material with sufficient heat resistance.However, burners have been improved in recent years and burners called high-speed burners have appeared, so burners Tiles were also forced to change their shape. In other words, in high-speed burners, it is necessary to discharge combustion gas at high speed, so the burner tile also has a cross-sectional shape that narrows toward the discharge port side, and high-load combustion within the burner tile is required. It's here. For this reason, burner tiles made of one-piece refractory material, as in the past, cannot withstand the sudden heat load during ignition and are prone to cracking, and because the outlet side of the burner tile is constricted, Combustion gas that has entered the cracks does not escape to the inside of the furnace, but instead enters the furnace wall, causing problems such as melting the heat insulating material and making the outer wall of the furnace red hot, or flames blowing out from the outer wall of the furnace.

(Problems to be Solved by the Invention) The present invention solves these conventional problems and provides a burner tile that does not cause cracks even when used in combination with a high-speed burner to perform high-speed combustion. It has been completed to provide the following.

(Means for Solving the Problems) The present invention has a thin inner cylinder made of a material with excellent heat resistance and thermal shock resistance, and an inner cylinder made of a material with excellent flexibility and heat insulation properties arranged around the outer circumference of the thin inner cylinder. It consists of a tube and an outer tube made of a material with excellent strength and placed around the outer circumference of the tube.

(Embodiment) Next, the present invention will be described in more detail with reference to the illustrated embodiment. Tll is an inner cylinder, (2) is a middle cylinder disposed on the outer periphery of the inner cylinder (1), and (3) is the outer periphery of the inner cylinder. The outer cylinder installed in (
4) is a holding member for the entire burner tile made up of these three members, and (5) is a burner head. The inner cylinder (1) is made of a material such as high-purity alumina refractory, which has heat resistance that can withstand high-load combustion and thermal shock resistance that can withstand thermal shock at the time of ignition. The wall thickness is made relatively thin in order to reduce the size. In addition, the thermal conductivity is about 1.0 to 15.0 Kca1/l1-hr・℃, the coefficient of thermal expansion is about 0.3 to 0.7% at 1000℃, the fire resistance is 1600℃ or higher, and the spall resistance is 20 to 20℃. 60
It is preferable to set it to about %. Here, the spall resistance is 1
A test piece heated to 200°C was put into water, rapidly cooled, and then rapidly heated to 1000°C again. The rapid cooling and rapid heat treatment was repeated three times, and the elastic modulus after treatment was changed by what percentage compared to the elastic modulus before treatment. It is shown as a measured value.

The middle cylinder (2) is made of a material such as ceramic fiber that is flexible to absorb the thermal expansion of the inner cylinder (11) and has excellent heat insulation properties.
Thermal conductivity at 0°C is 0.1-0.3Kcaj! /m
-hr・'c degree, fire resistance 1000℃ or more, bulk density 0.
05 to 0.28/cm' is preferable. As is clear from the drawings, the middle cylinder (2) is arranged on the outer periphery of the center or tip of the inner cylinder (11), but is not provided at the base near the burner head (5). The outer cylinder (3), which is used to securely hold the inner cylinder (1) by the outer cylinder (3), is made of a material with excellent strength such as castable refractory, and maintains the shape of the entire burner tile. This is to ensure secure attachment to the furnace body.The outer cylinder (3) has a small heat load compared to the inner cylinder (11), so it has particularly excellent heat resistance and thermal shock resistance. is not necessary, but in the example, the fire resistance is 1200℃,
Crimping strength: 400 kg/aa (1000°C) Thermal conductivity: 1.
2Kca 1271g-hr・'l:: (500℃)
, a castable refractory with a bulk density of 2.8 g/cd (1000° C.) is used.

In the illustrated embodiment, the burner tile has a cross-sectional shape that narrows toward the discharge port (6), but the present invention can also be applied to a conventional burner tile that widens toward the discharge port (6). Needless to say, it can be applied.

(Function) A tile configured in this way is attached to the furnace wall together with a burner and used for heating the furnace, as in the past, but the burner tile of the present invention has an inner cylinder ( 1) is made of a thin material with excellent heat resistance and thermal shock resistance, so it will not crack even when subjected to a high heat load, and will not undergo a strong thermal shock during ignition. There is no risk of cracks occurring even in the case of Moreover, the middle cylinder (2) placed on the outer periphery
absorbs the thermal expansion of the inner cylinder fi+ and prevents damage,
It keeps the inner cylinder warm, reduces the temperature difference inside the inner cylinder, and reduces the occurrence of thermal stress, which prevents cracks more reliably than the inner cylinder (11) cracks, and the middle cylinder (2) exhibits a heat insulating effect. This prevents heat transfer from the burner tiles to the furnace wall,
Better burner efficiency will be achieved. Since the outer cylinder (3) with excellent strength is placed on the outermost periphery, the entire burner tile can be securely attached to the furnace wall.
Mechanical vibration etc. can be prevented.

Note that the burner tile of the present invention is not necessarily limited to having a circular cross section, but may be square in cross section. It goes without saying that a multilayer structure of three or more layers is also included within the scope of the present invention.

(Effects of the Invention) As is clear from the above description, the present invention enables high-speed combustion to be performed in combination with a high-speed burner by making the burner tiles, which conventionally had an integral structure with refractories, into a multilayer structure. This eliminates the risk of cracks occurring even when the furnace wall is heated, and by using this, it is possible to prevent heat transfer to the furnace wall and damage to the furnace wall. Therefore, the present invention is a burner tile with a multilayer structure that eliminates the problems of the conventional ones.
The contribution to industrial development is extremely large.

[Brief explanation of the drawing]

The drawings are cross-sectional views showing embodiments of the present invention. (1): Inner cylinder, (2): Middle cylinder, (3I: Outer cylinder, (6):
Outlet.

Claims (1)

[Claims] 1. A thin inner cylinder (1) made of a material with excellent heat resistance and thermal shock resistance, and a middle cylinder (1) made of a material with excellent flexibility and heat insulation disposed around the outer periphery of the inner cylinder (1). 2) and an outer cylinder (3) made of a material with excellent strength placed around the outer periphery of the burner tile. 2. A burner tile with a multilayer structure according to claim 1, which has a cross section narrowed toward the discharge port (6) side.