JPH0720012A - Sampling device of low-temperature liquefied gas - Google Patents

Abstract

PURPOSE:To provide a low-temperature liquefied gas sampling device which can generate a vaporized gas of liquid having the same compositions as the liquid have, and continuously sample the vaporized gas at the time of analyzing low-temperature liquefied gas having different compositions in pipelines and reservoirs. CONSTITUTION:A sampling space section 17 is provided in pipelines 11a and 11b, containers, etc., for low-temperature liquefied gas by using a member in which at least a porous body 14 is partially arranged and such a heating source as the sheathed heater 18, etc., is provided in the vicinity of the porous body 14 in the space section 17. At the same time, a lead-out tube 19 for sampling gas is connected to the section 17 so as to bring the porous body 14 into contact with a low-temperature liquefied gas fluid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-temperature liquefied gas sampling device, and more specifically, to analyze low-temperature liquefied gas having various compositions flowing in a pipe, the low-temperature liquefied gas is continuously sampled and gasified. The present invention relates to a low-temperature liquefied gas sampling device which is supplied to an analyzer.

[0002]

2. Description of the Related Art A conventional general sampling method is shown in FIG. First, the first method is to connect the outlet pipe 2 to the pipe 1 for low temperature liquefied gas, and connect the outlet pipe 2 to the analyzer A via the valve 3. The second method is a branch pipe 8 having a valve 5, a valve 6 and a valve 7 in the outlet pipe 4 connected to the pipe 1.
And a sampling container 9 is detachably attached to the branch pipe 8.

[0003]

However, in the first method described above, the liquefied gas evaporates at an unspecified location in the outlet pipe 2 due to the heat intrusion from the outside, and thus the outlet pipe 2
Since the sampling liquid in the backflows or pulsates, the composition of the liquefied gas fluctuates, making it difficult to obtain an accurate liquid composition. Further, in the second method, the sampling container 9 has to be attached and detached each time the analysis is performed,
It took time and labor, and continuous analysis was not possible. Further, the sampling container 9 that collects a sample in a liquid state requires further consideration of pressure resistance and safety, and has a complicated structure.

For example, as an example of industrial sampling of low-temperature liquefied gas, a LNG sampling device is typical. This LNG sampling device evaluates the accurate unit calorific value of LNG by analyzing the composition of LNG, and is an important device for commercial transactions. In the conventional sampling device typified by such an LNG sampling device, the liquefied gas is extracted through a thin pipe, so that a part of the liquefied gas is prevented from vaporizing in the middle of the pipe due to heat loss of the pipe. Was very difficult. If even a portion of the liquefied gas is vaporized in the middle of the piping, the low boiling point components will preferentially evaporate.
The composition is richer in low boiling point components than the liquefied gas composition. On the other hand, since the high boiling point component is concentrated on the liquid side, the composition of the liquefied gas is changed, and not only the composition of the liquefied gas is different from the original composition, but also pulsation occurs in the flow. This pulsation also causes compositional variations, making it difficult to accurately analyze the liquid composition in a stable state. In addition, when sampling a large amount of liquefied gas continuously, the extracted liquefied gas is forcibly vaporized through a flexible pipe immersed in a warm bath, but it does not pulsate uniformly and at a stretch at once. It was technically difficult to evaporate.

Therefore, in the present invention, when analyzing low-temperature liquefied gas having various compositions in pipes and storage tanks, a low-temperature liquefied gas sampling apparatus capable of generating evaporative gas having the same composition as the liquid composition and continuously extracting it. Is intended to provide.

[0006]

In order to achieve the above-mentioned object, the low temperature liquefied gas sampling apparatus of the present invention defines a space portion by a member having a porous body arranged at least in a part thereof, and the space portion is defined in the space portion. , Preferably in the vicinity of the porous body,
A heating source is provided, a gas sampling outlet tube is continuously provided in the space, and the porous body is brought into contact with a low-temperature liquefied gas. Furthermore, a member for defining the space is provided. It is characterized in that a part thereof is a part of components such as pipes and containers for low temperature liquefied gas.

[0007]

[Operation] According to the above configuration, the low-temperature liquefied gas permeates the porous body due to the capillary phenomenon or pressure difference of the low-temperature liquefied gas and enters the space portion, and is heated by the heating source to penetrate the entire amount of the low-temperature liquefied gas Is continuously evaporated to form a gas having an accurate liquid composition and is supplied to the analyzer from the outlet pipe.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the embodiments shown in the drawings. FIG. 1 shows a first embodiment of the present invention, in which a sampling pipe 12 is provided in the middle of the pipes 11a and 11b for low temperature liquefied gas. The sampling pipe 12 is connected to both pipes 11a and 11b by flanges 13 and 13, and is formed in a double pipe structure in which a tubular porous body 14 is arranged as a space portion defining member. ing.

The tubular porous body 14, together with the ring-shaped closing plates 15 provided at both ends thereof, has a liquefied gas channel 16 and a sampling space 1 in the sampling tube 12.
7, and each joint is liquid-tightly joined.

In the vicinity of the outer peripheral surface of the porous body 14 in the space 17, a spiral sheathed heater 1 is used as a heating source.
8 is provided, and the outer tube portion 12 a of the sampling tube 12 is provided with a lead-out tube 19 that communicates with the space section 17.

The porous body 14 has a large number of minute holes through which the low temperature liquefied gas can permeate by a capillary phenomenon, has good wettability to the low temperature liquefied gas, has a large gas flow resistance, and has a low temperature liquefied gas. Various materials can be used as long as they can be used in the temperature range of, for example,
Sintered metal, unglazed ceramics, copper wool, etc. can be used. Among them, as is well known, the sintered metal has fine continuous pores of, for example, about 1 μm therein, and those used as various machine parts can be used as they are. . The type of metal may be any one such as stainless steel and copper.

The pore size of the porous body 14 may be any size as long as the low temperature liquefied gas can permeate from the inner peripheral surface to the outer peripheral surface of the porous body 14 by the capillary phenomenon. The wall thickness, diameter and the like can be set to an optimum size depending on the sampling amount of the low temperature liquefied gas as a sample. Further, in the case of the structure shown in this embodiment, since the liquid contact area of the porous body 14 can be formed large,
The solid impurities in the low-temperature liquefied gas can significantly reduce the risk that the through holes of the porous body 14 are blocked and fail to function, and it is also possible to sample a large amount of liquid. The surface of the porous body 14 on the low temperature liquefied gas side is
It is necessary that the entire surface be in contact with or immersed in the low temperature liquefied gas.

On the other hand, the sheathed heater 18 has a heating capacity capable of promptly evaporating the entire amount of the low temperature liquefied gas exuding from the porous body 14 in accordance with the sampling amount of the low temperature liquefied gas, A high-temperature fluid, for example, nitrogen gas may be circulated in the thin tube as a heating source as long as it has the same ability. Further, if a heat source such as the sheath heater 18 is provided in contact with the porous body 14 or the heating amount is too large, the low temperature liquefied gas penetrating into the porous body 14 is partially evaporated and The pressure may be increased to impede the permeation of the liquid, a predetermined sampling amount may not be obtained, and the evaporative gas may flow back to the low-temperature liquefied gas side. Therefore, a dry region may be formed on the surface of the porous body 14. The distance between the porous body 14 and the heating source and the heat input amount of the heating source are selected so as not to occur. Further, the sampling amount can be adjusted by adjusting the pressure of the space 17 for sampling and the heat input amount of the heating source.

In the low-temperature liquefied gas sampling device thus constructed, the low-temperature liquefied gas flowing in the pipes 11a and 11b is liquefied gas flow path 1 of the sampling pipe 12.
When passing through 6, it flows while contacting the inner peripheral surface of the porous body 14 and permeates into the porous body 14 only by the capillary action of the low temperature liquefied gas or by the capillary action and the pressure difference between the low temperature liquefied gas and the space 17. , Seeps into the outer peripheral surface of the porous body 14,
The exuded liquid is heated by the sheath heater 18 provided in the space 17 and quickly evaporates the entire amount, and then is sent to an analyzer (not shown) via the outlet pipe 19.
Further, since the gas evaporated in the space 17 does not flow backward through the porous body 14 due to the flow resistance of the porous body 14, the total amount of the evaporated gas is promptly discharged.
9 is derived.

That is, since the low-temperature liquefied gas exuding from the porous body 14 is evaporated uniformly and at a stroke, a gas having the same composition as the liquid composition is continuously and stably obtained, and this is led out. By supplying from 19 to the analyzer, it is possible to analyze the composition of the low temperature liquefied gas in a stable and highly accurate manner without causing composition change and flow rate fluctuation due to pulsation of the flow.

In this embodiment, the sampling tube 12 is provided with the porous body 14 formed in a tubular shape having a diameter smaller than that of the pipes 11a and 11b. However, the outer pipe portion 12a has a large diameter and the inner diameter of the porous body 14 is increased. Can be the same as the inner diameter of the pipes 11a and 11b. Further, the heat source of the sheathed heater 18 is not limited to electric heat, and nitrogen gas or the like at normal temperature may be circulated. If the low temperature liquefied gas is a flammable gas, the latter is preferable for safety.

Next, FIG. 2 shows a second embodiment of the present invention in which, contrary to the above embodiment, the inside of the tubular porous body 14 is used as a sampling space portion 17. That is, the tubular porous body 14 is used as a space portion defining member, a cap 21 is attached to one end of the tubular porous body 14, and an end plate 22 in which a lead-out tube 19 is continuously provided is attached to the other end for sampling. The space portion 17 is defined, and a spiral sheathed heater 18 similar to the above is arranged in the space portion 17.

In this embodiment, the pipes 11a and 11b are
The low-temperature liquefied gas flowing inside penetrates into the porous body 14 and exudes to the inner peripheral surface of the porous body 14, and the whole amount immediately evaporates by heating by the sheath heater 18 and is analyzed from the space 17 through the outlet pipe 19. Supplied to the meter.

In each of the above embodiments, the case where the low temperature liquefied gas in the pipe is sampled is illustrated, but the low temperature liquefied gas stored in the container or the low temperature in various equipment such as a distillation column and a condenser is used. It is also applicable to sampling of liquefied gas, and as the member that defines the space, a tubular porous body was used, but the shape of the porous body is not limited to this. For example, it may be spherical or box-shaped, or may be formed into a tubular or spherical shape by combining a porous body and a normal material in a half-divided form, or in the first embodiment, not on the entire circumference of the sampling tube but only on a part thereof. Provided or cap-shaped (hemispherical etc.) in the second embodiment
It is possible to form the tube into a tubular body made of a normal material and assemble it at one end, or to use the flat plate-shaped porous body in combination with other materials as needed. At this time, as described above, it is necessary to form the entire surface of the porous body so as to be in contact with or immersed in the low temperature liquefied gas.

Further, the basic requirement of the porous body in the present invention is that it serves as a flow resistance for the evaporated gas to flow back to the low temperature liquefied gas side, and has a function of allowing the low temperature liquefied gas to permeate by the surface tension. Therefore, although the porous body is optimally easy, it can be used in place of the porous body as long as it satisfies the above requirements, and is not limited to the through holes.

Further, as the low temperature liquefied gas, the above-mentioned L
Other than NG, it is not limited to cryogenic liquefied gas such as liquefied air, liquefied oxygen, liquefied nitrogen, liquefied argon, etc.
All liquids having a boiling point of room temperature or lower, such as PG, can be targeted. Although the input terminal of the heating source and the inlet and outlet pipes of the heating gas are not shown in FIGS. 1 and 2, it is desirable to attach them so as not to exchange heat with the low temperature liquefied gas as much as possible.

[0022]

As described above, the low-temperature liquefied gas sampling device of the present invention defines a space in which at least a part of the porous material is arranged, and a heating source is provided in the space. Since a discharge tube for gas sampling was provided in series in the space, the low-temperature liquefied gas was exuded to the surface of the porous body only by the capillary phenomenon or by the capillary phenomenon and the pressure difference, and the exuded liquid was heated. By evaporating,
The same gas composition as the liquid composition can be obtained. further,
Since the vaporized gas does not flow backward due to the flow resistance of the porous body, the entire amount of the vaporized gas is quickly discharged from the outlet pipe, and a stable flow rate is achieved without causing compositional changes and flow rate fluctuations due to flow pulsation. Therefore, an accurate liquid composition can be continuously and constantly obtained. Further, structurally, since the area of the portion in contact with the low-temperature liquefied gas can be increased, it is possible to prevent the solid impurities in the low-temperature liquefied gas from blocking even a part of the porous body and rendering it unusable. It is possible to sample a large amount of liquid. Therefore, according to the present invention, it is possible to analyze various low temperature liquefied gases extremely accurately.

[Brief description of drawings]

FIG. 1 is a sectional view of a sampling device showing a first embodiment of the present invention.

FIG. 2 is a sectional view of a sampling device showing a second embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a conventional low-temperature liquefied gas sampling method.

[Explanation of symbols]

11a, 11b ... Pipe for low-temperature liquefied gas, 12 ... Sampling pipe, 14 ... Porous body, 16 ... Liquefied gas flow path, 17 ...
Space part, 18 ... Sheath heater, 19 ... Outlet pipe

Claims (3)

[Claims] 1. A space portion is defined by a member in which a porous body is disposed at least at a part, a heating source is disposed in the space portion, and a gas sampling outlet pipe is connected to the space portion. A low-temperature liquefied gas sampling device, wherein the porous body is brought into contact with a low-temperature liquefied gas. 2. The low-temperature liquefied gas sampling device according to claim 1, wherein the heating source is arranged in the vicinity of the porous body. 3. A low-temperature liquefied gas sampling system according to claim 1, wherein a part of a member that defines the space is a part of a component member such as a low-temperature liquefied gas pipe or container. apparatus.