JP2001194278A - Device for refrigerating cell containing liquid sample, especially petroleum product sample to be analyzed - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerating device capable of refrigerating a cell containing a liquid sample especially a petroleum product sample to be analyzed to extremely low temperatures. SOLUTION: The refrigerating device includes a stirling cycle or pulse-type cooling unit 10 which is connected to an A.C. power source at one end, provided with a means capable of changing the pressure of a high-pressure operation gas periodically, and is constituted of a compression module 16 which operates with a cold finger 17. An operation chamber subdivided into a plurality of compartments and extended into the compression module 16 and cold finger 17 is filled with helium to enable extremely low temperatures to be obtained at this level by the expansion of the operation gas in the cold compartments placed at the end of the cold finger 17 opposite to the compression module 16 i.e., a first end 18. The refrigerating device includes a dry contact heat- transfer organ 11 on the other side which is mounted on the cold finger 17 at the level of the first end 18, enables a sample to be cooled to necessary temperatures, and operates with a cell containing a sample to be analyzed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for freezing a cell containing a sample of a larger or smaller viscous liquid, in particular a petroleum product to be analyzed in a temperature range extending from + 50 ° C. to −120 ° C. Related to the device.

[0002]

BACKGROUND OF THE INVENTION Certain physicochemical tests relating to the field of petroleum product analysis require cooling of the analysis cell, and the temperature of the sample contained therein may be up to -80 ° C or -120 in certain special cases. ° C and their tests include boundary filterability temperatu
re), melting point (thaw point), pour point (flow point),
Cloud point and also tag and Abel
nd Abel) Determining flash point is non-limitin
g) As an example.

For this purpose, a device of the type shown schematically in FIG. 1 is conventionally used, which comprises a tank of cold heat transfer liquid and a circuit for circulating this fluid in the direction of arrow a. 2 comprises a Rankine type cryostat 1 which cooperates with a circulation pump 3
including.

The circulation circuit 2 includes a coil 4 surrounding a cell 5 to be cooled. The assembly constituted by the coil 4 and the cell 5 to be cooled is placed in a constant temperature casing 6 containing a heat insulating material 7. The temperature probe 8 makes it possible to check the temperature of the cell 5 at a certain moment.

[0005]

SUMMARY OF THE INVENTION Including a sample cooled by contacting a coil in which a heat transfer fluid circulates;
This conventional device has several disadvantages.

[0006] Cooling the cell to a temperature of -80 ° C requires utilizing a heat transfer liquid at a temperature of about -85 ° C to -90 ° C, which uses a two-stage Rankine-type generator. It should be noted that at present, such cryo-generators are too bulky, cumbersome, loud, and fragile devices.

In addition, to cool the cell, a tank of cold heat transfer liquid must be available that remains fluid at very low temperatures, and methanol is currently mainly used for this purpose. However, it is also because other useful liquids considered for use are either very expensive or very volatile at ambient temperatures. Currently, due to its toxicity, the use of methanol in laboratories will probably be banned in the near future.

In addition, due to their relative brittleness,
Rankine-type cryogenic generators are not included in the analyzer, which requires thermally insulated connections to the latter, and these connections now have heat loss at the source of a high risk of leakage. And the overall efficiency of this type of cold source is very low.

Controlling the temperature of the cell requires careful handling due to the imbalance between useful and required energy and also the thermal shock imposed on the cell at each injection of heat transfer fluid. Note also that

The present invention addresses these drawbacks by providing an apparatus which makes it possible to freeze a cell containing a liquid sample, in particular a sample of the petroleum product to be analyzed, to a very low temperature. And

[0011]

SUMMARY OF THE INVENTION To this end, the present invention relates to an apparatus characterized in that: The device comprises, on the one hand, a Stirling cycle or a pulsed gas cooling unit, on the other hand, attached to this cooling unit, to analyze the sample to be analyzed so as to be able to cool the sample to the required temperature. A dry contact heat transfer tube cooperating with the containing cell. Stirling cycles or pulsed gas cooling units designed specifically for cooling electronic components to lower the temperature are generally described as:
Composed of a compression module cooperating with a cold finger, comprising means connected to an AC power supply and capable of periodically changing the pressure of the high pressure working gas, in particular helium comprises a plurality of helium extending between the compression module and the cold finger. Fills the subdivided working chamber and thus is obtained at this level by the expansion of the working gas in the cold compartment located at the opposite or first end of the cold finger with respect to the compression module. Very low temperatures to allow can be possible.

According to the invention, a dry contact heat transfer tube is mounted on the cold finger at the level of its first end.

The configuration of these heat exchanger tubes will vary depending on the tests to be performed.

According to a variant of the invention, suitable for the example of determining the boundary filterability temperature of a petroleum product according to the European standard prEN 116, the heat transfer tube is made of a tubular metal surrounding the cell containing the sample to be analyzed. A sleeve made of the same material is provided on the side wall of the sheath, the shape and dimensions of the sleeve corresponding to those of the first end of the cold finger, the sleeve being connected to this first end. Placed over.

In accordance with the present invention, the tubular sheath and the first end of the cold finger placed over the metal sheath are attached to the inner portion of a thermostatic casing containing insulation.

The configuration of the heat transfer tube depends, of course, on the type of cell to be cooled and, consequently, on the type of cell to be cooled.

In all cases, the heat transfer tube is equipped with a temperature probe which cooperates with a control tube which allows the temperature of the cell to be adjusted precisely.

More precisely, the Stirling cycle cooling unit is generally located substantially coaxially with the compression module, which is substantially cylindrical and which itself is also substantially cylindrical and which is an extension of the compression module. But,
A cold finger having a smaller diameter.

The compression module includes at least one main piston that is controlled by a linear or rotary motor supplied by an AC power supply and moves in a reciprocating motion to compress the working gas in the compression compartment. The cold finger itself is filled with a heat exchanger and mounted telescopically, with the same frequency as the main piston, but in opposite phase, so as to periodically change the pressure of the working gas in different compartments of the working chamber. A cooperating hollow sweep piston subdivides the cold finger in its inner portion into two compartments communicating with each other through a heat exchanger, i.e., while the cold compartment is the second of the cold finger. At one end, on the other hand, a hot compartment is located at the opposite end of the finger and connected to the compression compartment.

Such a cooling unit is known per se, and its construction is described, for example, in US Pat. No. 4,894,894.
No. 996 and U.S. Pat. No. 5,088,288 and are not described in further detail within this description for the sake of brevity.

Taking into account the vibrations generated by the periodic displacement of the main piston and the sweep piston, the cooling device according to the invention, when it is equipped with such a cooling unit, has a device for stopping those vibrations. You have to cooperate with the pipe inevitably.

To this end, according to another feature of the invention, the cooling unit is fixedly mounted on a ballast plate on its side walls by supporting legs, the ballast plate being, in particular, of a suitable mass of steel. And is substantially parallel to its longitudinal axis and rests on at least three and preferably four dampers.

[0023]

BRIEF DESCRIPTION OF THE DRAWINGS The features of this device, object of the present invention, will be explained in more detail with reference to the accompanying drawings.

Referring to FIG. 1, the cooling device may be a Stirling cycle or a pulsed gas.
gas) consisting of a cooling unit 10 and a heat transfer dry contactor tube 11 which allows cooling of the cell 12 containing the sample to be analyzed at the required temperature.

The assembly consisting of the heat transfer tube 11 and the cell 12 is mounted on the inner part of a constant temperature casing 13 containing heat insulating material 14. The temperature probe 15 makes it possible to determine the temperature of the cell 12 at a certain moment.

More precisely, the cooling unit 10
Comprises a compression module 16 cooperating with a cold finger 17, the cold end 18 of the cold finger being located opposite the compression module 16.
Pass through the dry contact heat transfer tube 11.

According to FIG. 3 and FIG.
0 includes a substantially cylindrical compression module 16 and a cold finger 17, the cold finger itself also being substantially cylindrical and positioned coaxially with an extension of the compression module 16. , The diameter of the cold finger 17 is smaller than that of the compression module 16.

The cooling unit 10 thus configured
The vibrations generated by the reciprocating motion of the piston, which is mounted and fixed by the supporting legs 16 on the side wall of the compression module 16 on a steel ballast plate 20 of determined mass, and which moves inside the cooling unit 10 And is in balance.

As shown in FIGS. 3 and 4, the ballast plate rests on four dampers 21 in parallel to the longitudinal axis of the cooling unit 10.

Referring to FIG. 3, the cold end 18 of the cold finger 17 is provided with a corresponding diameter annular copper sleeve 22.
It is covered with and placed.

The annular sleeve 22 is fixed to the side wall of a tubular copper sheath 24 surrounding a cell 25 for determining the boundary filterability temperature of the sample.

According to European standard prEN116, cell 2
5 comprises a specially shaped pipette 26 consisting of a reservoir, an inlet tube and an outlet tube connected to a vacuum source. The inlet tube passes through a stopper 27 closing the tubular sheath 24 and at its lower end is connected by a filter tube 29 to a container 28 containing the sample to be analyzed. The centering cage 30 is
This allows maintaining the inlet tube in the inner portion of the tubular sheath 24.

The stopper 27 further comprises a temperature probe 31 which makes it possible to determine the temperature inside the container 28 at any given moment.

Referring to FIG. 3, the assembly constituted by the tubular sheath 24 and the annular sleeve 22 positioned over the cold end 18 of the cold finger 17 comprises:
The dry contact heat transfer tube 11 is constituted.

The assembly 11 includes a cold finger 1 formed by a clamping lid 32 and an upper ring 33.
At the level of the cold end 18 of 7, it is fixed on a ballast plate 20.

Referring to FIG. 4, the dry contact heat transfer tube 11 '
Consists of a metal transmission plate 35 fitted on the cold finger 17 and is held thereto by clamps 34.

The transmission cover 35 rests against the cold end 18 of the cold finger 17 by the inner surface of its base 36.

The outer surface of the base 36 of the transmission plate 35, opposite its inner surface against the cold end 18 of the cold finger 17, holds a cell 37 for determining the melting point of the sample.

This cell 37 comprises an input orifice 38 and a vacuum evacuation orifice 39 for the sample to be analyzed, and two optical sensors 4 serving as light emitters and light receivers respectively.
0 and 40 '. A temperature sensor 41 fixed to the cell 37 by a clamp 42 gives the temperature of the sample to be followed at a certain moment.

[Brief description of the drawings]

FIG. 1 is a diagram of a conventional device.

FIG. 2 is a diagram similar to FIG. 1 of the device according to the invention.

FIG. 3 is an “exploded” perspective view of a device according to the invention suitable for determining the boundary filterability temperature of a sample contained in a cell according to the standard prEN-116.

FIG. 4 is a perspective view of an apparatus according to the present invention suitable for determining the melting point of a sample contained in a cell.

[Explanation of symbols]

Reference Signs List 10 Stirling cycle or pulse type gas cooling unit 11, 11 'Dry contact heat transfer tube 12 Cell 13 Constant temperature casing 14 Insulation material 15 Temperature probe 16 Compression module 17 Cold finger 18 Cold end 19 Support leg 20 Steel ballast plate 21 Damper 22 Annular copper sleeve 24 Tubular copper sheath 25 Cell 26 Pipette 27 Stopper 28 Container 29 Filter tube 30 Centering cage 31 Temperature probe 32 Clamping lidar 33 Upper ring 34 Clamp 35 Metal transmission plate (transmission cover) 36 Base 37 Cell 38 Input orifice 39 Evacuation orifice 40, 40 'Optical sensor 41 Temperature sensor 42 Clamp

Claims (5)

[Claims] 1. The method according to claim 1, wherein the sample of the petroleum product to be analyzed is approximately +
More or less viscous in the temperature range extending from 50 <0> C to -120 <0> C, especially to determine their boundary filterability temperature, their melting point, their pour point or their cloud point An apparatus for freezing a cell containing a liquid sample, comprising, on the one hand, a Stirling cycle or a pulsed gas cooling unit (10) comprising a compression module (16) cooperating with a cold finger (17), said cooling comprising: The unit is connected to an AC power source and comprises means capable of periodically changing the pressure of the high-pressure working gas, in particular helium is subdivided into a plurality of compartments and the compression module (16) and the cold finger (17) ) And located at the opposite or first end (18) of the cold finger (17) with respect to the compression module (16). In the cold compartment, the expansion of the working gas gives a very low temperature to be obtained at this level, while it is mounted on the cold finger (17) at the level of its first end (18). A dry contact heat transfer tube (11), which cooperates with the cell containing the sample to be analyzed and allows this sample to be cooled to the required temperature.
A refrigeration apparatus comprising: 2. The heat transfer tube (11) surrounding the cell (25) containing the sample to be analyzed, in particular made of copper,
A sleeve (22) of tubular metal sheath (24), the side wall of which is made of the same material, the shape and dimensions of said sleeve corresponding to those of said first end of said cold finger; The refrigeration device according to claim 1, wherein the refrigeration device is placed so as to cover the first end. 3. The heat transfer tube (11) and the first end (18) of the cold finger (17) are attached to an inner part of a constant temperature casing (13) including a heat insulating material (14). 3. The method according to claim 1, wherein
A refrigeration apparatus according to claim 1. 4. The refrigeration device according to claim 1, wherein the heat transfer tube (11) is provided with a temperature probe (15). 5. The cooling unit is controlled by a linear or rotary motor supplied by an AC power supply and moves at least in a reciprocating motion to compress the working gas in the compression compartment and the cold finger (17). 1
A substantially cylindrical compression module (16) including two main pistons, the cold fingers being substantially cylindrical and located coaxially with the module within an extension of the compression module, but more Having a small diameter, the compression module is filled with a heat exchanger and telescopically mounted, moves at the same frequency as the main piston but in phase opposition, the pressure of the working gas in a different compartment of the working chamber A hollow sweeping piston, which cooperates to vary periodically, which subdivides the cold finger (17) in its inner part into two compartments communicating with each other through the heat exchanger. That is, on the one hand the cold compartment is located at the first end (18) of the cold finger (17), while on the other hand the hot compartment is At the opposite end of the finger (17), it is connected to the compression compartment of the compression module (16), and the cooling unit (10) is supported on its side wall by support legs (19). Ballast board (2
0), which is rigidly mounted and fixed, said ballast plate being in particular made of steel substantially parallel to its longitudinal axis and resting on at least three and preferably four dampers (21). The refrigeration apparatus according to any one of claims 1 to 4, wherein: