RU2236634C1 - Exhaust duct - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: exhaust duct has outer metallic housing composed of the sections of gas duct and heat insulation covered with the inner protective metallic shell. The shell is made of the metallic envelope which is split along the longitudinal butt. The locator is mounted on the outer side near the face.

EFFECT: lowered vibration and enhanced reliability.

1 cl, 5 dwg

Description

The invention relates to mechanical engineering, in particular to thermal protection of objects, and can be used in the manufacture of the flow path of the exhaust tracts.

Known exhaust tract, for example, as 866326, IPC F 16 L 59/00, in which the internal thermal insulation is made in the form of heat-insulating mats covered with protective sheets. The metal sheets press the heat-insulating mats against the insulated outer casing by means of fixing bolts. For reliability of fastening of thermal insulation and compensation of thermal expansions of protective sheets, flexible couplers are hinged on them.

The closest in technical essence to the claimed solution is the device of the internal thermal protection of the exhaust tract, described in as 2185564, IPC F 16 L 59/00. The exhaust tract contains a power metal housing, consisting of sections of the gas duct. Needles are welded from the inside to the walls of the body, a heat-protective coating is pinned on the needles in layers and covered with a layer of fiberglass. Protective corrugated sheets are welded to the needles through washers. Between themselves, the sheets are welded along with intermittent lap seams, while the central transverse overlap is not welded. The sheets are fixed around the perimeter on the outer casing. On the side of the flow path, the joints of the gas duct sections are closed and welded with trough-like overlays.

The freedom of thermal expansion in the longitudinal direction is ensured by the fact that the protective sheets are not connected at the transverse joints, but in the transverse direction due to the fact that the sheets have longitudinal corrugations.

This exhaust path has the following disadvantages:

- a high likelihood of manufacturing errors due to the greater number of welding operations used when attaching the protective sheets, which reduces the reliability of the exhaust duct design;

- fasteners - washers protruding above the protective sheets are sources of disturbance of the gas flow, which leads to an increase in the level of vibration.

Based on the above-mentioned disadvantages, the possibility of tearing off the protective sheets due to the possibility of resonant oscillations of large amplitude is not excluded, since the set of protective sheets does not represent a single rigid shell, since the sheets are bonded to each other only at the points of attachment to the needles and along the longitudinal joints.

The implementation of the inner shell in the form of individual corrugated sheets, the use of welding and a large number of fastening elements makes the design as a whole low-tech.

The objective of the invention is to increase the resistance of the protective sheath to resonance phenomena and to increase the manufacturability of the design of the exhaust tract.

When solving this problem, the following technical result is achieved - reducing the level of vibration and, as a result, noise, increasing the reliability of the design of the exhaust tract.

The technical result is achieved by the fact that in a known exhaust path comprising an outer metal casing, consisting of sections of a gas duct, a heat-insulating coating closed by an internal protective metal casing having circumferential movement and not connected along transverse joints, fixed in the outer casing around the perimeter and closed in places of joints by overlays, the shell is made in the form of a shell, open along the longitudinal joint, with a fixing element on its outer surface in the area of the end face towards the flow of the work environment. The locking element is made in the form of a split ring placed in the grooves of the guides, fixed along the axis of the housing.

During the search, no technical solutions were found for similar installations that would include the claimed distinctive features - the shell in the form of a shell, open along the longitudinal joint, with a fixing element on its outer surface in the end zone facing the flow of the working medium, while maintaining the possibility of movement in circumferential and axial direction during expansion. The use of the claimed distinctive features in conjunction with the remaining essential features will allow you to get the new above-mentioned positive and technical result that is not inherent in known similar devices, as well as separately known in the prior art features. Thus, the claimed technical solution meets the criterion of inventive step, as it is characterized by a new design of features and their new combination and relationship with the achievement of a new technical result from their use.

Figure 1 presents a longitudinal section of the exhaust tract; figure 2 - the junction of the sections of the gas duct, which shows a method of fixing the shell relative to the outer casing; figure 3 is a transverse section of the exhaust tract; figure 4 - open joint shell; figure 5 - shell.

The exhaust duct contains an outer metal housing 1, consisting of sections of a gas duct 2 (Fig. 1). Guides (stringers) 3, 4 with grooves in the end zone are welded to the walls of the outer casing 1 from the inside (Fig. 2). A needle 5 is welded between the guides 3, 4. A heat-shielding coating 6 is pinned on the needles 5 in layers. The inner shell is made in the form of a metal shell 7, open along the longitudinal joint, between the open ends of which a gap L is formed to ensure thermal expansion in the circumferential direction, and in the zone the end face of the shell 7, facing the flow of gases, on its outer surface a shoulder 8 is welded, which is a split ring (figure 3). The gap L is determined by calculation, depending on the brand of material of the shell 7 and the temperature of the working medium. The shell 7 with its shoulder 8 is fixed in the grooves of the guides 3 and 4 and due to the stresses that occurred during the manufacture of the shell from sheet metal, it fits tightly on the guides 3, 4 and the heat-shielding coating 6 (Fig. 2). The non-closed ends of the shell 7 have the possibility of circumferential movement along the grooves of the guides 3, 4 towards each other when it expands.

The open longitudinal joint of the shell 7 is overlapped by a plate 9 attached by spot welding to a T-shaped guide 4 in zone K (Fig. 4). At the junction of the gas duct sections between the ends of adjacent shells, a gap M is formed, which ensures freedom of thermal expansion of the shell in the axial direction. The gap M is determined by calculation, depending on the brand of material of the shell 7 and the temperature of the working medium. The gap M is overlapped by a lining 10 welded to one of the shells.

Flanges 11 are welded to the outer surface of the outer case.

As a result of heating the shell 7 by the flow of hot gases, the ends of the open shell 7 move in the circumferential direction towards each other within the gap L (Fig. 4), compensating for thermal expansion. Burt 8 (figure 3) does not interfere with the movement of the ends of the shell 7 in the circumferential direction, moving in the grooves of the guides 3 and 4. The end face of the shell 7, facing the gas flow, lies freely on the guides 3 and moves under the influence of thermal expansion in the axial direction within gap M. Due to its integrity, the shell 7 is not subject to destruction and is able to perform only low-amplitude oscillations, which increases the reliability of the exhaust tract as a whole.

Instead of the gaps L and M, an overlap can be made, providing freedom of thermal expansion.

Power sealed housing 1 is made of steel St.3 or 09G2S with a thickness of 3-6 mm.

The inner shell 7 is made of stainless steel type 12X18H10T with a thickness of 1-1.5 mm. The gas duct sections 2 are joined together by flanges 11 using bolted connections.

Thus, a continuous inner shell is obtained:

- the integrity of which allows you to exclude multiple fasteners and joints by welding, and also eliminates its destruction and reduces the amplitude of resonant vibrations;

- the design of which provides freedom of thermal expansion in the axial and circumferential directions without the use of corrugations, which allows them to be excluded.

Based on the above, a design is obtained that has higher manufacturability and reliability compared to the prototype.

Claims (2)

1. An exhaust duct comprising an outer metal casing consisting of gas duct sections, a heat-shielding coating closed by an internal protective metal shell having circumferential movement, not connected along transverse joints, fixed in the outer casing along the perimeter and closed at the joints of the gas duct sections by overlays, characterized in that the shell is made in the form of a shell, open along the longitudinal joint, with a locking element on its outer surface in the area of the end face facing the flow of the worker her environment. 2. The exhaust duct according to claim 1, characterized in that the fixing element is made in the form of a split ring placed in the grooves of the guides fixed along the axis of the housing.

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