JPH0120545Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial field of application This invention relates to an open rack type evaporator for vaporizing liquefied natural gas.This invention prevents the bowing phenomenon that occurs in the lower header tank of the heat exchange panel and improves stability during operation. This invention relates to an evaporation device designed to improve performance and extend the life of panels.

BACKGROUND TECHNOLOGY An open rack type evaporator, for example, has a finch tube with a pair of fins protruding in the diametrical direction arranged in the direction of the fins to form a single panel, and header tanks are provided at the top and bottom ends of the finch tube to form a heat exchange panel. The structure is such that sea water, which is a heat medium, flows down onto the heat exchange panel surface from a water sprinkler placed above the panel.

In a conventional evaporator, during operation, the heat medium such as seawater that is sprinkled is scattered on the upper outer periphery of the horizontally arranged lower header tank, reducing the amount of heat medium flowing down to the lower outer periphery. Due to the temperature difference in the vertical direction, the so-called bowing phenomenon occurs, where the header tank deforms into an arched shape.
The lower part of the finch tube, especially the part where the fins have been removed for welding to the header tank during assembly, may be bent, and there is a risk of damage to this part and the equipment due to increased stress due to the change in shape due to the removal of the fins. There were problems with durability.

In addition, in order to prevent this Boeing phenomenon,
A technology was proposed to attach a heat-insulating structure to the lower header tank to limit heat input from the outside.
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However, in the above evaporator, when seawater is sprinkled as a heat medium and liquefied natural gas is vaporized,
When the equipment is started, due to the density difference between the gas and liquid liquefied natural gas, the low-temperature liquid natural gas comes into contact only with the lower inner peripheral surface of the lower header tank, resulting in a large temperature difference in the vertical direction of the lower header tank. This is insufficient to prevent the Boeing phenomenon.

Purpose of the invention In view of the above-mentioned current situation, this invention aims to improve the lower header tank, prevent the bowing phenomenon that occurs in the lower header tank, and provide an open rack type evaporator with a configuration that can extend the life of the panel.

Structure and effect of the invention This invention consists of a heat exchange panel with a series of finch tubes and header tanks installed at the upper and lower ends.
In an open rack type evaporator that evaporates liquefied gas by sprinkling water from a water sprinkler disposed above the panel, a member for blocking at least the lower half of the lower header tank cross section so that the liquefied gas does not come into contact with the lower half of the cross section of the lower header tank, This is an open rack type evaporator characterized in that it is installed at least at both ends in the longitudinal direction within a lower header tank.

In this invention, a member that closes at least the lower half of the cross section of the lower header tank is placed inside the header tank, only at both ends in the longitudinal direction.
Alternatively, it is characterized in that it is provided in other parts or over the entire length, and the closing member can be made of any material such as a heat insulating material with low thermal conductivity, or may be formed integrally with the header tank.

Further, the lower header tank may have any structure other than a normal single pipe structure, even if it has a double pipe structure, as long as the liquefied gas does not come into contact with at least the outermost inner circumferential surface of the lower half of the lower header tank.

For example, if the header tank is a single tube, a plate member configured as a flat plate or T-shaped in cross section may be inserted into the header tank in the longitudinal direction. A passage pipe section equivalent to a sparge pipe for supplying liquefied gas is provided on the longitudinal plane part to form an integral structure, and an extruded material with an outflow hole for the liquefied gas in the passage pipe section is inserted into a single pipe of the header tank. Various configurations can be adopted, such as a structure that prevents liquefied gas from coming into contact with the lower half of the header tank.

By adopting the configuration of this invention, the liquefied gas does not come into direct contact with the inner circumferential surface of the lower half of the lower header tank, which reduces the temperature drop in this area and reduces the temperature difference between the upper and lower outer circumferential surfaces of the header tank. Therefore, the bowing phenomenon can be prevented.

Disclosure of the invention based on drawings This invention will be described in detail below based on drawings of embodiments. 1 and 2 are longitudinal sectional views of the lower header tank in the open rack type evaporator according to this invention.

Here, the open rack type evaporator is formed by arranging a fin tube having a plurality of pairs of fins protruding in the diametrical direction in the fin direction to form a single panel shape.
Header tanks are provided at the upper and lower ends of the heat exchange panel to form a heat exchange panel, and seawater as a heat medium is caused to flow down onto the heat exchange panel surface from a sprinkler placed above the panel.

The lower end of the finch tube 1 has a finless part 2 with the fin removed.
is erected by welding at the upper end of the outer periphery of the lower header tank 3.

The lower header tank 3 has a double pipe structure, and is composed of an outer header pipe 4 and a sparge pipe 5 built into the pipe. The liquefied gas passes through the sparge pipe 5 and enters the header pipe 4 from the hole on the upper side. The structure is such that the water flows into the finch tube 1 and further rises within the finch tube 1.

In Fig. 1, inside this lower header tank 3,
Closing members 6 were installed at both ends in the longitudinal direction. That is, in the lower header tank 3, a semi-cylindrical closing member 6 made of a heat insulating material is fitted into approximately the lower half between the header pipe 4 and the sparge pipe 5.

In Fig. 2, inside this lower header tank 3,
A closing member 6 was installed over the entire length in the longitudinal direction. In the lower header tank 3, everything except the rising part of the opening to the finch tube 1 between the header pipe 4 and the sparge pipe 5 can be closed.
In other words, a closing member 6 made of a cylindrical heat-insulating material is inserted into the cylindrical body, which is made of a cylindrical heat-insulating material and has liquefied gas passage holes drilled in the axial direction at intervals of the finch tubes 1 in the longitudinal direction of the cylindrical body. Gas flows into the finch tube 1 from the hole at the top of the sparge pipe 5 through the liquefied gas passage hole of the closing member 6.

In the part where the above-mentioned closing member 6 is provided, the header pipe 4 of the part of the lower header tank 3 is
Since the liquefied gas does not come into direct contact with the inner peripheral surface, the temperature drop in this area is reduced, and the temperature difference between the upper and lower parts of the outer peripheral surface of the lower header tank becomes negligibly small, making it extremely effective in preventing the bowing phenomenon. Obtainable.

In the case of Fig. 1, the closing member 6 is installed at the part of the entire length of the lower header tank 3 that is most affected by the phenomenon, and in the case of Fig. 2, the closing member 6 is installed over the entire length of the lower header tank 3, which prevents the occurrence of the bowing phenomenon. An increase in stress was prevented, damage to the finless portion 2 was eliminated, and the life of the heat exchange panel could be dramatically extended.

[Brief explanation of the drawing]

1 and 2 are longitudinal sectional views of the lower header tank in the open rack type evaporator according to this invention. 1... Finch Yube, 2... Finn Mube, 3
... lower header tank, 4 ... header pipe, 5 ... sparge pipe, 6 ... closing member.

Claims (1)

[Scope of utility model registration request] In an open rack type evaporator in which a heat exchange panel is constructed by arranging finch tubes and header tanks are provided at the upper and lower ends, and in which liquefied gas is evaporated by sprinkling water from a water sprinkler disposed above the panel, at least the lower half of the lower header tank cross section. An open rack type evaporator characterized in that members for closing off the portions are installed at least at both ends in the longitudinal direction within the lower header tank so that the liquefied gas does not come into contact with the portions.