JPH0337080B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a main pipe made of a metal pipe with a heat insulating material formed on the inner periphery, a pipe having a smaller diameter than the main pipe, and a heat insulating material on the outer periphery. This invention relates to a connection structure with a branch pipe made of a metal pipe formed with a metal pipe.

[Conventional technology]

In recent years, recovery of sensible heat contained in high-temperature exhaust gas has been widely implemented as one of the energy-saving measures in various industrial furnaces. By the way, for this purpose, it is necessary to minimize the temperature drop of the high-temperature exhaust gas in the duct, and as a means for this, a heat insulating material is formed in the duct.

By the way, ducts with heat insulating material formed on them include those with heat insulating material formed on the inner periphery of a metal pipe and those with heat insulating material formed on the outer periphery of a metal pipe. When trying to connect, for example, as shown in the cross-sectional view of Figure 1,
A branch pipe made of a metal pipe 2 having a diameter smaller than that of the main pipe and having a heat insulating material formed on the outer periphery is connected to a main pipe made of a metal pipe 1 having a heat insulating material formed on the inner periphery. A piping structure is adopted in which a hole corresponding to the diameter of the metal tube 2 is provided for connection.

[Problem that the invention seeks to solve]

However, in the conventional piping structure as described above, when trying to raise the temperature of the exhaust gas to improve the recovery efficiency of exhaust gas sensible heat, a portion comes into contact between the metal pipe 1 and the exhaust gas, resulting in the following drawbacks. Ta.

(a) When common carbon steel is used as the metal tube 1, the portion of the metal tube 1 that comes into contact with the exhaust gas is exposed to high-temperature exhaust gas, which tends to cause deterioration due to oxidation and deformation due to thermal distortion.

(b) Heat dissipation from the metal tube 1 to the outside increases, and heat recovery efficiency tends to decrease significantly.

[Means for solving problems and their effects]

The present invention aims to eliminate the various drawbacks of the conventional piping structure, and includes a main pipe made of a metal pipe with a heat insulating material formed on the inner circumference of the exhaust gas duct, and a pipe smaller than the main pipe. The main pipe and the branch pipe have a diameter smaller than that of the main pipe and a diameter smaller than that of the branch pipe at the connection part with a branch pipe made of a metal pipe with a heat insulating material formed on the outer periphery. A pipe connection structure in which the pipes are connected by a connecting metal pipe with a large diameter, and a heat insulating material made of ceramic fiber or the like is formed on the inner and outer peripheries of the connecting metal pipe, respectively. By doing so, the main pipe, which is made of a metal pipe with an insulating material formed on the inner periphery, eliminates the part where it comes into contact with the exhaust gas, and prevents deterioration of the main pipe due to oxidation, deformation due to thermal distortion, and heat radiation to the outside as much as possible. The objective is to provide a piping connection structure that

Next, the present invention will be specifically explained based on the drawings. FIGS. 2 and 3 show a main pipe made of a metal pipe with a heat insulating material formed on the inner periphery of an exhaust gas duct equipped with a piping structure according to the present invention, and a pipe having a smaller diameter than the main pipe and an outer periphery. FIG. 2 is a cross-sectional view of a connection portion with a branch pipe made of a metal pipe on which a heat insulating material is formed.

In these figures, 1 is a main pipe made of a metal pipe with a heat insulating material formed on the inner periphery, and is generally made of carbon steel. A branch pipe 2 is made of a metal pipe with a heat insulating material formed on its outer periphery, and is generally made of a heat-resistant metal such as stainless steel. The main pipe 1 is provided with a connecting metal pipe 6 made of a heat-resistant metal such as stainless steel and having a diameter smaller than that of the main pipe 1 and larger than that of the branch pipe 2, which is in the same circle as the branch pipe 2. It is attached by welding in a centrally arranged state, and the other end of the connecting metal pipe 6 has an outer diameter corresponding to the pipe diameter of the connecting metal pipe 6, and an inner diameter corresponding to the pipe diameter of the branch pipe 2. A donut-shaped metal plate 7 made of a heat-resistant metal such as stainless steel corresponding to the pipe diameter is attached by welding, and the metal plate 7 is attached to the branch pipe 2.
It is attached by welding.

In addition, in these figures, the heat insulating material formed on the inner periphery of the main pipe 1 includes a ceramic fiber sleeve-shaped molded body 3 inside and a sheet-like material such as a ceramic fiber blanket 4 wrapped in multiple layers around the outer periphery. It is a heat insulating material made of a ceramic fiber blanket or irregularly shaped ceramic fiber material 8, and the heat insulating material formed around the outer periphery of the branch pipe 2 is a heat insulating material having a structure in which a ceramic fiber blanket or rock wool felt 5 is wound in multiple layers. . Further, the heat insulating material attached to the inner wall of the connecting metal pipe 6 is a ceramic fiber sleeve-shaped molded body 9.

Here, the ceramic fiber sleeve-shaped molded body 9 used in the present invention has approximately the same inner diameter as the branch pipe 2, and has a length that reaches the innermost side of the heat insulating material provided on the inner wall of the main pipe 1. It has a certain quality.

When the heat insulating material formed on the inner periphery of the main pipe 1 is a combination of a ceramic fiber sleeve shaped body and a ceramic fiber blanket, the ceramic fiber sleeve shaped body 9 is attached in advance. After the material is installed in the main pipe 1, a hole is provided in the heat insulating material in the main pipe 1 for inserting the ceramic fiber sleeve-like molded product 9, and the ceramic fiber sleeve-like molded product 9 is inserted into the hole. On the other hand, when the heat insulating material is a ceramic fiber irregularly shaped member 8, a ceramic fiber sleeve-like molded body 9 is attached in advance, and then the ceramic fiber irregularly shaped member is attached. The ceramic fiber sleeve-shaped molded body 9 is fixed, if necessary, from the side surface of the connecting metal tube 6 with a metal pin 10 made of a heat-resistant metal such as stainless steel.

〔Effect of the invention〕

As described above, according to the present invention, the piping structure of the exhaust gas duct includes a metal pipe with a heat insulating material formed on the inner periphery and a heat insulating material formed on the outer periphery, as shown in FIGS. 2 and 3. Since the insulation material is effectively installed at the connection with the metal pipe, the metal pipe with the insulation material formed on the inner periphery is not directly exposed to exhaust gas, preventing deformation due to thermal oxidation and thermal distortion. At the same time, the heat dissipation from the connection can be significantly reduced, and the temperature drop of the exhaust gas passing through the duct is extremely efficiently prevented, thereby significantly improving the efficiency of sensible heat recovery in the exhaust gas. It is extremely useful for industry.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a conventional piping connection structure of an exhaust gas duct consisting of a metal pipe with a heat insulating material formed on the inner periphery and a metal pipe with a heat insulating material formed on the outer periphery;
FIGS. 2 and 3 are cross-sectional views showing the piping connection structure of an exhaust gas duct, which is composed of a metal tube with a heat insulating material formed on the inner periphery and a metal pipe with a heat insulating material formed on the outer periphery of the present invention. . In the drawings, 1...metal tube with a heat insulating material formed on the inner periphery, 2...metal tube with a heat insulating material formed on the outer periphery, 3...ceramic fiber sleeve-shaped molded body, 4...ceramic fiber blanket , 5... Ceramic fiber blanket or rock wool felt, 6... Metal pipe for connection,
7... Donut-shaped metal plate, 8... Ceramic fiber irregular shaped material, 9... Ceramic fiber sleeve-shaped molded body, 10... Metal pin.

Claims (1)

[Scope of Claims] 1. A main pipe made of a metal pipe with a heat insulating material formed on the inner periphery, and a branch pipe made of a metal pipe with a diameter smaller than the main pipe and with a heat insulating material formed on the outer periphery. In the connection structure, the main pipe and the branch pipe are connected by a connecting metal pipe having a pipe diameter smaller than that of the main pipe and larger than the branch pipe, and the connecting metal pipe is A pipe connection structure having a heat insulating structure, characterized in that a heat insulating material is formed on the inner and outer circumferences of the pipes. 2. Claim 1, wherein the heat insulating material is a sleeve-shaped molded body made of any one of the following compositions: ceramic fiber and binding material, ceramic fiber, binding material and fireproofing material, or fireproofing material and binding material. A connection structure for piping having a heat insulating structure as described in Section 1.