JPH04185997A - Evaporator for low temperature liquefied gas - Google Patents

Abstract

PURPOSE:To prevent frosting and icing by providing plural evaporating units and a evaporated gas heating unit connecting the flow outlet part of each evaporating unit to a common piping through a valve, and connecting the common piping to the heating unit in an evaporation for liquefied oxygen or the like. CONSTITUTION:An evaporator A is composed of two evaporating units 1 and 2, consisting of two finned pipe 6, and one heating portion 3 consisting of one finned pipe 6. Pipes 9a and 9b of flow outlet parts of the evaporating units 1 and 2 are connected to a common piping 11 through respective valves 4 and 5. The pipe 12 of the flow inlet part of the heating unit 3 is also connected to the common piping 11. In this arrangement, for example, the valve 4 is opened and the valve 5 is closed so as to connect the evaporating unit 1 to the heating unit 3, and liquefied gas stored in a CE is supplied to the evaporating units 1 and 2 through pipes 8c, 8a and 8b. The liquefied gas is thus supplied from the evaporating unit 1 to an apparatus through the heating unit 3, while the evaporating unit 2 is in standby. If the evaporating unit 2 is iced over, opening/closing of the valves 4 and 5 is changed over so as to make the evaporating unit 1 stand by, perform deicing, and start up the evaporating unit 2.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an evaporator that evaporates low-temperature liquefied gas by exchanging heat with the atmosphere.

<Prior Art> Currently, low-temperature liquefied gases (hereinafter referred to as "liquefied gas 1") such as liquefied oxygen, liquefied nitrogen, liquefied argon, and liquefied carbon dioxide gas are used in large quantities in medical institutions or factories. It is stored in an evaporator (CE), etc., and when used, it is stored in an atmospheric heat exchange type evaporator (hereinafter referred to as evaporator 1).
After being evaporated and vaporized in the evaporator, it is supplied to the target equipment through predetermined piping.

As disclosed in, for example, Japanese Utility Model Publication No. 51-29546, the above-mentioned evaporator is constructed by arranging fin pipes in which a plurality of fins are formed in the longitudinal direction in parallel in the longitudinal direction, and connecting these fin pipes with bent pipes. connected and configured. The supplied liquefied gas exchanges heat with the atmosphere while flowing through the fin pipe, becomes a gas heated to a predetermined temperature, and passes through the secondary pipe located downstream of the evaporator. It is supplied to specified equipment.

Also, the performance of the evaporator is set by the amount of evaporation per unit time, and this evaporation capacity is determined by the type of liquefied gas.

It is set by a heat exchange area that satisfies conditions such as the temperature of vaporized gas.

In the above evaporator, the liquefied gas is evaporated and vaporized by heat exchange with the atmosphere, so depending on the atmospheric conditions, the supply of liquefied gas may cause frost to form on the liquefied gas supply side of the evaporator, causing the evaporator to be used for a long time. This frost can grow and form ice. When frost or ice builds up on the evaporator, heat exchange with the atmosphere is inhibited, and as a result, gas that is not sufficiently heated is supplied to secondary piping and equipment, causing low-temperature brittleness of piping materials, Otherwise, there is a risk that the equipment may malfunction. In addition, ice may grow and have a negative impact on the foundation of the evaporator.

In order to solve the above problem, (1) If frost or ice forms on the evaporator, knock off this deposit with a hammer.

■Stop using the evaporator periodically to thaw frost and ice.

■ Install multiple evaporators with the same performance and switch between them.

■Use an evaporator with a higher evaporation capacity.

Currently, the following measures are being taken.

<Problems to be Solved by the Invention> However, in the above cases (1) and (3), the operating efficiency deteriorates and is not a fundamental solution, and (2) increases the equipment cost. In addition, (2) has problems such as high equipment costs and frost or ice formation due to long-term use, which is not a basic solution.

An object of the present invention is to provide an evaporator for low-temperature liquefied gas that solves the above problems.

<Means for Solving the Problems> In order to solve the above problems, the evaporator for low-temperature liquefied gas according to the present invention includes a plurality of fin pipes having fins formed in the longitudinal direction, and a plurality of fin pipes having fins formed in the longitudinal direction. An evaporator for low-temperature liquefied gas configured in a connected manner, including a plurality of evaporators for evaporating the supplied low-temperature liquefied gas, and a temperature raising unit for raising the temperature of the evaporated gas in the evaporator. The outlet of each of the evaporating sections is connected to a common piping via a valve for opening and closing the outlet, and the common piping is connected to the inlet of the temperature increasing section. be.

Effect> According to the above means, the liquefied gas can be evaporated and vaporized in a stable state for a long period of time without significantly increasing the equipment cost.

Frost or ice formation in the evaporator is concentrated in the area where the supplied liquefied gas evaporates, and there is almost no frost or ice formation on the area where the temperature of the steam is raised. Therefore, the evaporator is divided into an evaporation section for evaporating the liquefied gas and a temperature raising section for raising the temperature of the steam. By connecting through the evaporation section, it is possible to select the evaporation section to be connected to the temperature raising section.

That is, the liquefied gas is evaporated and vaporized by connecting an arbitrary evaporation section and a temperature raising section in the evaporator. When frost builds up in this evaporation section and the vaporization efficiency decreases, the valve provided at the outlet of the evaporation section is closed, and the valves of other evaporation sections are opened and connected to the temperature raising section. As a result, the liquefied gas flows into the newly connected evaporation section and is evaporated, and this vapor flows out to the temperature raising section and is heated.

At this time, the liquefied gas in the closed evaporation section evaporates but does not flow out, so the internal pressure increases, and this pressure causes the liquefied gas remaining in the evaporation section to flow back toward the supply side. Therefore, no new liquefied gas is supplied to the evaporator, and the evaporator itself heats up through heat exchange with the atmosphere, melting the frost and ice that have adhered to it.

As described above, in the evaporator according to the present invention, by selectively operating a plurality of evaporators, other evaporators can be stopped. Therefore, liquefied gas is not supplied to the stopped evaporator. As a result, frost forms on the stopped evaporator.

There is no icing, and it is possible to maintain a state where good heat exchange can be performed at all times.

<Example> An example of an evaporator to which the above means is applied will be described below with reference to the drawings.

FIG. 1 is a plan view of the evaporator, FIG. 2 is a side view of the evaporator, and FIG. 3 is a block diagram of the evaporator.

In the figure, the evaporator A has two evaporating sections 1.2 and one temperature increasing section 3. Evaporation sections 1 and 2 and temperature raising section 3 are connected via pulp 4.5, and by operating these valves 4.5, evaporation section 1 or 2 can be connected to temperature raising section 3. It is configured so that it can be selectively connected.

The evaporation sections 1 and 2 and the temperature raising section 3 are each constructed using a fin vibro in which a plurality of fins 6a are formed in the longitudinal direction by extruding aluminum, and heat exchange with the atmosphere is performed through the fins 6a. By doing this, the liquefied gas is evaporated and vaporized.

For this reason, the evaporation sections 1 and 2 and the temperature raising section 3 are
A predetermined number of fin vibros are arranged vertically and horizontally (in the vertical and horizontal directions in FIG.
It is constructed by connecting these fin vibros in parallel and series.

As shown in the figure, the evaporation section 1.2 is constructed by arranging 15 fin vibros in 3 series in the vertical direction and 5 in series in the lateral direction. By connecting the fin vibros arranged in the horizontal direction in series through the bend pipe 7, three series of flow passages 1a to IC and flow passages 28 to 2C are formed.
By connecting the fin vibros arranged on the upstream side of the series with tubes 8a and 8b, and connecting the fin vibros arranged on the downstream side with tubes 9a and 9b, flow paths 1a to lc are constructed. , 2a to 2C are connected in parallel.

The pipes 8a and 8b are connected by a supply pipe 8C, and a flange 8d is provided at a predetermined position of the supply pipe 8C. As shown in FIG. 3, the supply pipe 8C and CE14. ! : is configured so that the liquefied gas stored in the CE 14 can be supplied to the evaporation section 1.2.

In this embodiment, the supply pipe 8C is provided at a position lower than the lowest position of the bend pipe 7 that connects the fin vibros that constitute the evaporator section 1.2 in series. For this reason,
Even if the liquefied gas is supplied to the evaporator 1 or 2 which is not operating, the liquefied gas easily flows back toward the CE 14 when the internal pressure of the evaporator 1 or 2 increases.

Further, the pipes 9a and 9b are provided with valves 4 and 5 for opening and closing the pipes 9a and 9b, respectively, and the evaporation section 1.2 is connected to the common pipe 11 via these pulps 4.5. There is.

The temperature raising section 3 is constructed by arranging 30 fin vibros in 6 series in the vertical direction and 5 in series in the lateral direction. Similarly to the evaporator section 1.2, by connecting the fin vibros arranged laterally in series through the bend pipes 7, 6 series of flow passages 3a to 3f are constructed.
The fin vibros located on the upstream side of each series are connected through a pipe 12, and the fin vibros located on the downstream side are connected through a pipe 13, thereby connecting the flow paths 3a to 3f in parallel.

Said pipe 12 is connected to the common pipe 11 of the evaporator section 1.2. Further, a flange 13a is provided at a predetermined position of the pipe 13, and is connected to a secondary pipe 15 shown in FIG. 3 via this flange 13a.

In the evaporator A configured as described above, evaporation sections 1 and 2
The number of fin vibros in the temperature raising section 3 is set in advance according to conditions such as the type of liquefied gas and the amount of evaporation.

That is, when conditions such as the type of liquefied gas, supply pressure, evaporation amount, supply temperature to the secondary side, and atmospheric conditions are set, the evaporation section 1. The required amount of heat to be exchanged in 2 and the amount of heat to be exchanged in the temperature increasing section 3 are set.

Furthermore, when conditions such as the surface area of the material 1 of the fin vibro are set, the heat transfer coefficient is set. Therefore, it is possible to calculate the required surface areas of the evaporation sections 1 and 2 and the temperature raising section 3 from the required exchange heat amount and heat transfer coefficient, and it is possible to set the number of fin vibros based on the calculated values. It becomes possible.

For example, using an aluminum fin vibro, the liquefied gas is saturated liquid liquefied nitrogen, and the supply pressure is 10k.
g/cj f, the evaporation amount is 30ON/h, the supply temperature of vaporized gas is atmospheric temperature -10°C, and the atmospheric conditions are 0°C or more and humidity 90% or less. Calculating the required surface area in the temperature rising section 3 and the required surface area in the temperature raising section 3, the surface area At in the evaporating section 1.2 is 20.
285ryf, and the surface area in the temperature rising section 3 is
becomes 82.652nf.

Therefore, the surface area A calculated as above, A3
It is possible to set the number of fin vibros in the evaporation section 1.2 and the temperature raising section 3 based on the value of the surface area of the fin vibros per unit length.

The surface area ^1 of the evaporation section 1.2 is the area necessary to evaporate the supplied saturated liquid of liquefied nitrogen into saturated vapor, and the surface area ^1 of the evaporation section 1.2 is the area necessary to evaporate the supplied saturated liquid of liquefied nitrogen into saturated vapor. There is a possibility that it may leak into the temperature rising section 3. For this reason, it is preferable that the surface area of the evaporation section 1.2 is set larger than the above value.

Furthermore, if the type of liquefied gas is different, the surface area ^1 of the evaporation section 1.2 and the surface area ^ of the temperature raising section 3 will have different values. However, it is preferable that the evaporator A is configured to be able to handle a plurality of liquefied gases.

For this reason, it is advantageous to set the ratio of the surface area ^ of the evaporating section 1.2 to the surface area A of the temperature raising section 3 in the range of 20% to 35%.

In the above configuration, for example, by opening the valve 4 and closing the valve 5, the evaporating section 1 and the temperature increasing section 3 are connected, and the CuI2 pulp 14a is opened and the CE14 is opened.
When the liquefied gas stored under pressure is supplied to the evaporation section 1.2 through the pipes 8c, 8a, and 8b, the liquefied gas supplied to the evaporation section 1 flows through the flow passages 1a to IC of the evaporation section 1. In the process, it evaporates and becomes saturated steam, which flows through the pipe 9a and valve 4. It passes through the common pipe 11 and reaches the temperature rising part 3 from the pipe 12 of the temperature rising part 3,
The temperature is raised to a predetermined temperature while flowing through the flow passages 3a to 3f of the temperature raising section 3, and the fluid is supplied from the pipe 13 through the secondary pipe 15 to equipment not shown.

In addition, since there is no flow of liquefied gas in the evaporation section 2, the supplied liquefied gas evaporates and vaporizes, increasing the internal pressure, so that no new liquefied gas is supplied to the evaporation section 2. Therefore, the evaporator 2 is maintained in a standby state without frost, ice, etc. adhering to it.

When a predetermined period of time has elapsed after the liquefied gas has been evaporated and vaporized as described above, and frost or ice has adhered to the evaporator 1 and the evaporation capacity of the evaporator 1 has decreased, the pulp 4 is closed and the valve 5 is closed. By opening the evaporator 2 and connecting the evaporator 2 in a standby state to the temperature raising part 3, the liquefied gas supplied from the CuI 2 is evaporated in the evaporator 2 and the vapor is supplied to the temperature raising part 3. Stop the operation of 1. At this time, the evaporator 1, which has stopped operating, is heated by the atmosphere and the adhering frost and ice melts, and the liquefied gas inside evaporates and vaporizes, increasing the internal pressure, causing the evaporator 1 to generate new The system enters a standby state without being supplied with sufficient liquefied gas.

As described above, in the evaporator A according to the present invention, the temperature raising section 3 includes the evaporating section 1. 2 can be selectively connected. For this reason, the evaporator 1 or 2, which has stopped operating, is always in a standby state and can function as an evaporator at a desired time.

Furthermore, if frost or ice adheres to the currently operating evaporator, it is possible to switch between the currently operating evaporator and the standby evaporator by operating the pulp 4.5. Therefore, by constantly operating the evaporator A in a stable state without impairing its evaporation capacity, and by stopping the operation of the evaporator section on which frost or ice has adhered, it is possible to eliminate the frost that has adhered to it.

It becomes possible to melt ice, and after the frost and ice melt, it becomes possible to maintain this evaporation section in a standby state.

<Effects of the Invention> As explained in detail above, in the evaporator for low-temperature liquefied gas according to the present invention, when frost or ice adheres to the currently operating evaporator, the evaporator can be switched to the standby state. By switching the operation to the evaporator section located in the evaporator, the evaporation capacity of the evaporator is always stabilized, and frost and ice attached to the evaporator section, which has stopped operating due to the switch, can be melted by heat exchange with the atmosphere. Therefore, the evaporation capacity of the evaporator can always be maintained in a stable state.

In addition, the heat exchange area of one evaporation section in the evaporator should be 20% to 20% of the sum of the heat exchange area of the evaporation section and the heat exchange area of the heating section.
By setting it to 35%, this evaporator can be made compatible with multiple types of liquefied gases.

Further, by integrally configuring the plurality of evaporation sections and temperature raising sections, the operability of the evaporator can be improved and the installation area can be reduced.

In addition, by providing the liquefied gas supply ports for the plurality of evaporators below the lower ends of the pipes connecting the fin pipes constituting the evaporators, the liquefied gas supplied when the evaporators stop operating is It has features such as being able to reverse flow.

[Brief explanation of drawings]

FIG. 1 is a plan view of the evaporator, FIG. 2 is a side view of the evaporator, and FIG. 3 is a block diagram of the evaporator. A is the evaporator, 1.2 is the evaporation section, la to lc, 2a to 2c
is a flow path, 3 is a temperature rising section, 4.5 is a valve, 6 is a fin vibe, 6a is a fin, 7 is a bend pipe, 8 a to 8 c,
9 a, 9 b, 12.13 is a tube, 8d, 1
3a is a flange, 10 is a frame, 11 is a common pipe, 1
4 is CE, and 15 is secondary piping. Patent applicant Koike Oxygen Industry Co., Ltd.

Claims (4)

[Claims] (1) An evaporator for low-temperature liquefied gas constructed by erecting a plurality of fin pipes each having fins formed in the longitudinal direction and connecting these fin pipes to evaporate the supplied low-temperature liquefied gas. A plurality of evaporation sections are provided, and a temperature raising section is provided to raise the temperature of the gas evaporated in the evaporation section, and the outlet of each evaporation section is connected to a common pipe through a pulp for opening and closing the outlet. An evaporator for low-temperature liquefied gas, characterized in that the common pipe is connected to an inlet of a temperature rising section. (2) The heat exchange area in one evaporation section is the sum of the heat exchange area in this evaporation section and the heat exchange area in the heating section ¥2
Claim (1) characterized in that the amount is 0% to 35% ¥.
The described evaporator for low temperature liquefied gas. (3) The evaporator for low-temperature liquefied gas according to claim (1) or (2), characterized in that a plurality of evaporation parts and temperature raising parts are attached to one frame and configured integrally. (4) A claim characterized in that a supply port for supplying low-temperature liquefied gas to a plurality of evaporators is provided below the lower end of a fin pipe constituting the evaporator or a pipe connecting the fin pipes. The evaporator for low-temperature liquefied gas according to any one of 1) to (3).