DE1259914B - Process for the liquefaction of helium - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

F25j

German KL: 17 g -1

Number: 1259 914

File number: S 910461 a / 17 g

Filing date: May 13, 1964

Opening day: February 1968

The invention relates to a method for liquefying helium, which is at supercritical pressure compressed, cooled by heat exchange to below its inversion temperature, in a first Stage relieved of throttle to an intermediate pressure, after further cooling through heat exchange in a second stage is throttle relaxed to the condensing pressure and partially liquefied, wherein a partial flow branched off from the cooled pressure helium before the throttle expansion, performing work relaxed to condensing pressure, together with re-evaporated helium in heat exchange with the helium gas is heated to around ambient temperature and recompressed.

The so-called Kapitza process is known for liquefying helium. This is where the a high pressure compressed helium gas throttled twice, first before entering a front a second throttle element lying countercurrent to an intermediate pressure and in the second throttle element on the condensing pressure. The first throttling of the high pressure gas has only the purpose, the pressure ratio between high pressure and low pressure gas in the heat exchanger before the last throttle device, to be more finite at a given temperature difference Size at the warm end of the heat exchanger, which is decisive for the cooling capacity to be delivered is a temperature difference at the cold end of the heat exchanger of a finite size to reach. As can be seen from the TS diagram for helium, if the pressure is too high, the process gas to be liquefied at the cold end of the heat exchanger, the temperature difference if necessary even disappear completely or at least be so small that heat exchangers are uneconomical large dimensions would be required.

In contrast, the invention has a method for liquefying helium as an object made, with which compared to previously common methods such. B. also the Kapitza method, the same cooling capacity can be generated with a lower compression capacity.

Accordingly, the method according to the invention is that the branch of the work-performing to be relaxed partial flow takes place after throttling to the intermediate pressure and the Partial flow heated by heat exchange with the pressure helium before the work-performing expansion will.

The same cooling capacity can be achieved with a lower one with the aid of the method according to the invention Process for the liquefaction of helium

Applicant:

Sulzer Brothers Aktiengesellschaft,
Winterthur (Switzerland)

Representative:

Dipl.-Ing. H. Marsch, patent attorney,

4000 Düsseldorf, Lindemannstr. 31

Named as inventor:

Dipl.-Ing. Sahabettin Ergenc, Zollikerberg
(Switzerland)

Claimed priority:
ao Switzerland of April 29, 1964 (5628)

Compaction performance compared to the previously

* 5 borrowed procedures are generated by by Throttling of the entire high-pressure gas flow to an intermediate pressure, a subsequent division takes place in two partial flows, of which the first partial flow is used, the non-throttled High-pressure gas to remove heat and through work-performing relaxation of the intermediate pressure to apply cooling capacity in an advantageous manner to approximately the condensing pressure while the second partial flow is throttled to the condensing pressure, taking advantage of the fact that due to the low pre-cooling temperature generated by the first throttling of the with the help of Second throttling achieved cooling effect is great because one caused due to the Joule-Thomson effect Cooling by throttling is the more favorable, the lower the temperature it is carried out.

In an advantageous device for performing the method according to the invention, a Part of the cooling capacity to be applied is generated in one or more expansion turbines. With gradual work-performing relaxation of the partial flow, it can be advantageous between two successive ones Stages are cooled by heat exchange.

If necessary, it can be advantageous to generate part of the cooling capacity together with the partial flow a further flow of helium gas

709 747/179

to relax work-performing, which relaxes work-performing by a greater pressure on the intermediate pressure and has been cooled by heat exchange and the work-performing relaxation to approximately the temperature that the partial flow has after heat exchange with the pressure helium. ^:

FIGS. 1 to 3 show different embodiments Variants of systems for the implementation of a throttle valve 17 relaxes, whereby he himself partially liquefied, and introduced into a container 18, from which the liquefied product passes through a removal line 19 can be removed via a closure member 20.

The non-liquefied portion of the second partial flow and any evaporated liquid flow through the heat exchangers 16 and. 10, in which they are almost

tion of the method according to the invention, all of which heat the pre-cooling temperature T _vl. After Aus

Figures are highly schematic and only the details necessary to illustrate the invention demonstrate.

In the exemplary embodiment of the invention according to FIG. 1, the gas to be liquefied is compressed in a compressor 1, preferably to supercritical pressure / and, after the compression heat has been dissipated in a cooler 2, by heat exchangers 4, 5, 6 and 7, which, for example, act as a so-called plate -Fin-Exchanger are designed, conducted, in which it is through heat exchange with cooler gas. "_; cools, -which will be explained in more detail later. Then .wird the high pressure gas in one of two adsorbers 8 and 9, which are alternately regenerated, of ^ residual

20th

When the gas emerges from the heat exchanger 10, the gas is merged with the gas expanded in the expansion turbine 15 and flows through heat exchangers 7, 6, 5 and 4, in which it is heated up to ambient temperature by heat exchange with non-throttled high-pressure gas, back to the intake side of: Compressor 12 or compressor 1. An amount of raw gas corresponding to the amount of product withdrawn is fed to the suction side of the compressor 1 via a line 3 ^ ..

As a numerical example for the liquefaction of helium, some information is given below. Thus, the helium can be compressed in the compressor 1 to about 18 ata and expanded in the throttle valve 11 to an intermediate pressure of about 5 ata ... which is also still in the supercritical pressure range for helium. In the compressor 12, helium is compressed to about 7 ata and expanded in the expansion turbine 14 to about 3 ata and in the expansion turbine 15 to a pressure of about 1.25 ata slightly below the condensing pressure of the helium. The pre-cooling temperature T _vl in the exemplary embodiment according to FIG. 1 is approximately 6 ° K and the pre-cooling temperature T _vll after the first throttling is approximately 5.4 ° K, while the liquefaction temperature in the container 18 is approximately 4.5 at the specified pressure of 1.25 ata ° K.

According to the embodiment of FIG

impurities freed. The high pressure gas is was and designated _left this Zeitpunkt'durch heat exchange to a preliminary cooling-Cooled that folgenden'mit in T is below DER inversion temperature of the gas.

Now the high pressure gas is in a heat exchanger'10 further "cooled and relaxed in a throttle valve 11 to an intermediate pressure. This Intermediate pressure is chosen so that although a cooling of the gas, but no liquefaction ■ in the Throttling takes place;} Now .. the throttled Gas divided into two partial flows, of which the first partial flow is returned through the heat exchanger 10 will and see through heat exchange

with the unthrottled high-pressure gas to almost ₄₀ , the gas is heated in a single-stage compressor 1 to pre- _{cooling temperature Γ νΙ.} Then it occurs in the selected high pressure compressed and in heat further heat exchange with the high pressure gas
in the heat exchanger 7.

At the outlet of the heat exchanger 7, the first partial flow is combined with a further gas flow. This gas flow is in a compressor 12 to a pressure between the High pressure gas and the intermediate pressure of the throttled high pressure gas is compressed, after dissipation of the compression heat in

a cooler 13 is further cooled by the heat exchanger 4 and finally expanded in an expansion turbine 45 to a pressure which is somewhat below the condensing pressure in the container 18. The gas originating from the container 18 is heated in the heat exchangers 16 and 43 to almost the pre-cooling temperature Γ _{νΙ of} the high-pressure gas, then combined with the gas expanded in the expansion turbine 45 and passed through the heat exchangers 42, 41 and 40, in which it continues to

tense. Now that the first part warms up to about ambient temperature, from the grain flow Related process steps described pressor 1 sucked.

In this exemplary embodiment, the cooling power to be applied from the pre-cooling temperature T _vl to the ambient temperature is generated essentially by work-performing expansion of the first partial flow.

. Another embodiment according to FIG. 3 relates to a variant embodiment of FIG. 2 loading

exchangers 40, 41 and 42 cooled to the pre-cooling temperature .Tvi, then further cooled by heat exchange with the first substream in a heat exchanger 43 and then expanded in the throttle valve 11 to an intermediate pressure. The first partial flow is returned through the heat exchangers 43, 42 and 41, heated in the process and then expanded in an expansion turbine 44. The gas that cools down in the process is stored in the heat exchanger 41

leads, in which it cools down, then expanded in an expansion turbine 14, and finally in the heat exchanger 6 continues to almost the temperature of the first substream at the point of Cooled together and combined with the first substream. The combined amount of gas is then removed in an expansion turbine 15 to almost the liquefaction pressure of the gas are, in the following, the second branched off after the first throttling Process steps relating to partial flow are described.

_{This second substream} enters a heat exchanger 16 at a pre-cooling temperature Γ νΙΙ, in which it cools down further. Then he will

plus the generation of the cooling capacity above the pre-cooling temperature T _vl . The four heat exchangers located in front of the first throttling of the high-pressure gas are also provided with the reference numerals 40 to 43 in accordance with FIG. In contrast to the previous exemplary embodiment, in the present case the _{cooling power to be applied above the pre-cooling temperature T VI} up to ambient temperature is generated by work-performing expansion of part of the high-pressure gas compressed in the compressor 1. A portion of the high-pressure gas already cooled in the heat exchanger 40 below ambient temperature is branched off, expanded in an expansion turbine 46 to approximately the intermediate pressure of the first partial flow, cooled in the heat exchanger 41 to almost the temperature of the first partial flow leaving the heat exchanger 42 and combined with it. The gas is then expanded in an expansion turbine 47 to almost the liquefaction pressure of the high-pressure gas in the container 18 and merged with gas originating from the container 18 after this has been heated in the heat exchangers 16 and 43 to almost the pre-cooling temperature T _vl sucked in again by the compressor 1 after it has been heated in the heat exchangers 42, 41 and 40 to about ambient temperature.

Claims (3)

Patent claims: 1. Process for the liquefaction of helium, which compresses to supercritical pressure, cooled by heat exchange to below its inversion temperature, in a first stage The throttle is released to an intermediate pressure, after further cooling through heat exchange in in a second stage the throttle is released to the condensing pressure and partially condensed, whereby a partial flow branches off from the cooled pressure helium before the throttle expansion, relaxed to the condensing pressure while performing work, together with re-evaporated helium in the Heat exchange with the helium gas warmed to about ambient temperature and compressed again is characterized in that the diversion of the work to be relaxing Partial flow takes place after throttling to the intermediate pressure and the partial flow before the work-performing relaxation is heated by heat exchange with the pressure helium. 2. The method according to claim 1, characterized in that the partial flow is gradual relaxed while performing work and between two successive stages through heat exchange is cooled. 3. The method according to claim 1, characterized in that together with the partial flow Another stream of helium gas is expanded to perform work, which is at a higher pressure On the intermediate pressure work-performing relaxed and through heat exchange and the work-performing Relaxation has been cooled approximately to the temperature that the partial flow having after heat exchange with the pressure helium. Considered publications:
German Auslegeschrift No. 1036 282;
U.S. Patent No. 3,094,390;
"Technische Rundschau Sulzer", 3/1963, pp. 121 to 125; "Handbuch der Kältetechnik", Volume 8, p. 91. 1 sheet of drawings 709 747/179 1.68 © Bundesdruckerei Berlin