Device for generating a temperature-controlled cold gas stream

Abstract

A device for generating a temperature-controlled cold gas stream, comprising a gas supply line for conducting a gas stream and a withdrawal line for withdrawing liquefied gas, the withdrawal line being connected to a storage tank and leading into the gas supply line at a nozzle portion, is characterized, according to the invention, in that flow bodies for generating a turbulent flow in the gas supply line are disposed in the gas supply line, on the radial exterior of the nozzle assembly.

Description

[0001] Device for generating a tempered, cold gas stream

[0002] The invention relates to a device for generating a tempered, cold gas flow, comprising a gas supply line for passing a gas flow and a liquid supply line connected to a storage tank for cold liquefied gas, which opens into the gas supply line at an inlet device with a nozzle section arranged within the gas supply line.

[0003] Cryogenic media, such as nitrogen, oxygen, or carbon dioxide, are often stored in liquid form in thermally insulated tanks. Since the stored medium is usually required in gaseous form by consumers, the stored medium is converted into the gas phase after the liquid is withdrawn. This is usually done using air-heated evaporators (hereinafter also referred to as "air evaporators"). However, air-heated evaporators have the disadvantage that ice formation can occur, particularly under adverse weather conditions and / or heavy loads, which can significantly impair the evaporator's functionality.

[0004] Instead of air-heated evaporators, however, heat exchangers can also be used in which the liquid medium comes into indirect thermal contact with a heat transfer fluid and evaporates while the heat transfer fluid cools. Such heat exchangers are designed, for example, as tubular heat exchangers or as cooling coils. The heat transfer fluid can, in particular, also be a process fluid that arises as a warm medium during an industrial process and must be cooled to a lower operating temperature before further use. For example, this could be a hot product stream or a cooling medium, in particular cooling water, that is conducted in a cooling circuit using a refrigeration system, which is thus at least relieved of its load by the evaporation of the cryogenic medium.The use of such heat transfer fluids for evaporating cryogenic media at least partially eliminates the need for the user to separately cool the heat transfer fluid to its operating temperature and / or the aforementioned problems associated with using an air-heated evaporator. However, the use of heat transfer fluid-controlled heat exchangers is problematic because the heat transfer fluid often does not have a constant heat content over time, or the heat transfer fluid flow rate is irregular. As a result, the temperature of the evaporated cryogenic medium fluctuates in a manner that is difficult to control. However, there are applications that require the use of a cold gas stream with a stable temperature. For example, in the carbonation of beverages, the so-called

[0005] The degree of carbonation, i.e., the amount of carbon dioxide that can be dissolved in the beverage or in the water used to make the beverage, depends sensitively on the temperature of the supplied carbon dioxide gas. The carbon dioxide used for this purpose is usually stored in a cold, liquefied state in low- or medium-pressure tanks and evaporated before being added to the beverage or water. In such cases, the use of a heat transfer fluid with a widely fluctuating heat content to evaporate the carbon dioxide has so far been avoided; instead, a complex separate device for evaporating and tempering the carbon dioxide gas has been used.

[0006] DE 10 2020 001 082 A1 discloses a device and a method for generating a temperature-controlled, cold gas stream. The device is equipped with a storage tank and a withdrawal line connected to the storage tank for withdrawing liquefied gas from the storage tank, as well as with a heat exchanger integrated into the withdrawal line, where the gas conveyed through the withdrawal line evaporates. A liquid supply line branches off from the withdrawal line, downstream of the storage tank and upstream of the evaporator unit. This liquid supply line rejoins the withdrawal line at an inlet device downstream of the evaporator unit, enabling temperature-controlled admixture of liquefied gas with the evaporated gas.This arrangement has proven successful, but the two components downstream of the feed device require a comparatively long distance to achieve a high degree of temperature homogeneity, which in turn leads to increased space requirements, higher construction costs, and increased energy consumption. The invention is therefore based on the object of creating a device for generating a temperature-controlled, cold gas stream by mixing in a stream of liquefied gas, in which rapid mixing and temperature homogenization occur.

[0007] This object is achieved in a device of the type and purpose mentioned above in that the gas supply line in the region of the nozzle section is equipped with flow means for generating a turbulent flow in the gas stream guided through the gas supply line.

[0008] According to the invention, the nozzle section of the liquid supply line is arranged within the gas supply line, preferably concentrically therewith. The nozzle section has one or more outlet openings, which preferably open radially at the nozzle section and / or counter to the gas flow direction into the gas supply line. The liquefied gas from the liquid supply line is introduced through the outlet opening(s) in the form of fine droplets into the gas stream conveyed through the gas supply line. These droplets are entrained by the gas stream and gradually evaporate, extracting heat from the surrounding gas stream.

[0009] Furthermore, the gas supply line, in the area where the nozzle section is located, is equipped with flow media, by means of which a turbulent flow is generated in the gas stream guided through the gas supply line downstream of the flow media. This promotes rapid and efficient mixing of the gas stream with the introduced liquefied gas. The flow media can be arranged upstream or downstream of the nozzle section in the gas supply line, as seen in the direction of gas flow. However, it is preferred that the flow media are arranged at least partially at the level of the nozzle section in the gas supply line and are designed such that the gas stream is guided along the surface of the nozzle section, whereby this acts as an additional heat exchanger for cooling the gas.

[0010] The flow media can be flow bodies molded into the inner wall of the gas supply line or attached to it, such as profiles protruding into the interior of the gas supply line or a profile of the gas supply line pipe itself. For example, the flow media can be baffles attached to the gas supply line and protruding into the interior of the gas supply line. The flow media are preferably designed to direct the gas flow guided through the gas supply line onto the outer surface of the nozzle section. This acts as a heat exchanger surface, further cooling the gas flow.

[0011] The gas supplied through the gas supply line and the liquefied gas supplied from the liquid supply line are preferably the same substance, such as nitrogen or oxygen; both may originate from different sources or from a common source, such as a storage tank.

[0012] A particularly advantageous embodiment of the invention provides that a plurality of baffles are provided as flow means, which extend from at least a partial section of the inner wall of the gas supply line to at least approximately an outer surface of the nozzle section.

[0013] For example, the deflection plates are flat, approximately semicircular disc-shaped bodies whose curved edge section is preferably attached in a gas-tight manner to the inner wall of the tubular gas supply line, and whose straight edge section extends transversely inside the gas supply line, reaching at least approximately to the outer surface of the nozzle section. This creates a constriction within the gas supply line, forcing the gas stream to flow along the surface of the nozzle section.

[0014] In a particularly preferred embodiment, the baffles, in particular the previously described semicircular disc-shaped elements, are arranged obliquely in the gas supply line, at an angle of preferably between 30° and 75°, particularly preferably between 40° and 50°, relative to the gas flow direction. The gas flow guided through the gas supply line thus encounters the baffles at an obtuse angle and is directed by them toward the outer surface of the nozzle section. Preferably, a plurality of flow media are arranged one behind the other (as seen in the gas flow direction) in the gas supply line along the nozzle section. The gas flow is thus guided several times in succession to the surface of the nozzle section and is thereby further cooled.

[0015] In a similarly advantageous embodiment of the invention, two flow media are arranged symmetrically to each other on opposite sides of the nozzle section in the gas supply line in the region of the nozzle section. If the flow media are the aforementioned deflection plates, this configuration results in a slot-shaped passage within which the nozzle section is arranged. Preferably, several pairs of flow media are arranged one behind the other (as seen in the direction of gas flow) and are rotated relative to the front pair by an angle of, for example, 90° around the axis of the gas supply line.

[0016] A preferred nozzle section is equipped with a porous body made of sintered metal or sintered ceramic. This is a preferably cylindrical or conical porous body through whose pores the liquefied gas is introduced from the liquid line into the gas supply line. The liquefied gas is thus introduced in the form of fine droplets into the gas, which is guided by the flow bodies close to the surface of the sintered body, thereby achieving a particularly intimate mixing of gas and liquid.

[0017] In order to further improve the efficiency of cooling the gas flow, it is advantageous to align the nozzle section of the liquid feed line within the gas feed line in such a way that the liquefied gas flows inside it in countercurrent to the gas in the gas feed line.

[0018] In a preferred embodiment of the invention, both the gas stream in the gas supply line and the liquefied gas in the liquid supply line originate from the same source. For this purpose, the gas supply line is connected to a storage tank for liquefied gas, to which the liquid supply line is also connected. A heat exchanger or evaporator is integrated into the gas supply line, which ensures the evaporation of the liquefied gas from the storage tank. The thus evaporated gas is then passed as a gas stream through the gas supply line and tempered with the help of liquefied gas metered in via the liquid supply line. In this case, heat from a process gas can also be used, particularly in the heat exchanger, to evaporate or partially evaporate the gas.

[0019] Advantageously, the device according to the invention comprises an automatic control system by means of which the supply of liquefied gas mixture from the liquid supply line into the gas stream guided through the gas supply line can be controlled according to measured or predetermined parameters, for example the temperature of the gas stream before and / or after the supply of the liquefied gas.

[0020] Embodiments of the invention will be explained in more detail with reference to the drawings. The schematic views show:

[0021] Fig. 1 : The circuit diagram of a device according to the invention,

[0022] Fig. 2a: An introduction system for liquefied gas of the inventive

[0023] Device from Fig. 1 in longitudinal section,

[0024] Fig. 2b: The entry system from Fig. 2a in a view rotated by 90° around the longitudinal axis and

[0025] Fig. 3: The entry system from Fig. 2a / 2b in a plane III-III in Fig.

[0026] Top view seen in 2a.

[0027] A device of the type shown in Fig. 1 serves, in particular, to generate a temperature-controlled cold gas stream, such as is used particularly in the food industry, for example, in the carbonation of beverages or the inerting of food products. In a device for carbonating beverages, the vaporized carbon dioxide is fed into a beverage and at least partially dissolved therein. The desired or achievable degree of carbonation depends, among other things, on the temperature of the supplied gas and therefore requires uniform temperature control of the supplied gas stream during production.

[0028] The device 1 comprises a thermally well-insulated storage tank 2 for a cryogenic liquefied gas, for example, liquid nitrogen or liquid carbon dioxide. Liquefied gas is withdrawn from the storage tank 2 via a withdrawal line 3 and fed to an evaporator unit 4.

[0029] In the example shown here, the evaporator unit 4 comprises a heat exchanger 5, in which the liquefied gas comes into indirect thermal contact with a heat transfer fluid and evaporates in the process. The heat transfer fluid is, for example, a medium that must be cooled anyway during an industrial process and whose excess heat can be advantageously used to evaporate the liquefied gas. For example, the heat transfer fluid is a cooling medium that flows through a cooling circuit 6 for the purpose of cooling an industrial process. In the heat exchanger 5, the heat transfer fluid comes into indirect thermal contact at a heat exchanger surface 7 with the liquefied gas from the storage tank 2, which is fed via the part of the extraction line 3 upstream of the heat exchanger 5.The liquefied gas evaporates completely or partially and flows further as evaporated gas through a gas supply line 8 on the downstream side of the heat exchanger 5.

[0030] In the event that, in the embodiment shown here, the heat input from the heat transfer fluid into the liquefied gas in the heat exchanger 5 is not sufficient to completely evaporate the liquefied gas, the evaporator unit 4 has an air evaporator 10 arranged parallel to the heat exchanger 5. A control valve

[0031] 11 controls the flow of the liquefied gas into the heat exchanger 5 and / or the air evaporator 10 depending on a parameter which is measured at a sensor

[0032] 12 in the gas supply line 8 and which is in particular the temperature or the consistency of the gas in the gas supply line 8. However, within the scope of the invention, it is not necessary for the evaporator unit 4 to comprise both an air evaporator 10 and a heat exchanger s; what is essential is that the liquefied gas evaporates completely in the evaporator unit 4.

[0033] A liquid supply line 13 branches off from the extraction line 3, downstream of the storage tank 2 but upstream of the evaporator unit 4, which opens into the gas supply line 8 at an inlet device 15 described in more detail below, downstream of the evaporator unit 4. The liquid supply line 13 is equipped with a control valve 16, which regulates the inflow of liquefied gas into the gas flowing through the gas supply line 8 depending on a parameter measured at a measuring device 17 downstream of the inlet device 15 in the gas supply line 8, in particular the temperature of the evaporated gas. The measuring device 17 can of course also be arranged upstream of the inlet device 15 on the gas supply line 8.

[0034] During operation of the device 1, liquefied gas is withdrawn from the storage tank 2, vaporized in the vaporizer unit 4, and supplied to its intended use in a consumer 14 connected to the gas supply line 8. For example, the consumer 14 is a device for carbonating beverages. In this case, it is necessary that the gas in the consumer reaches the consumer 14 at a temperature as precisely defined as possible (determination temperature).

[0035] However, the amount of heat introduced into the vaporized gas via the heat exchanger 5, the air evaporator 10, and / or other sources is not always sufficiently constant and can fluctuate over time. For example, the amount of heat introduced via the air evaporator 10 depends in particular on atmospheric factors, such as ambient temperature, ambient pressure, or air humidity, which make precise adjustment of the temperature of the vaporized gas in the gas supply line 3 difficult or even impossible. The temperature of the vaporized gas in the gas supply line 8 upstream of the introduction device 15 therefore depends on various factors; within the scope of the invention, however, it should be above the target temperature, which can, however, be ensured if necessary by a heating device (not shown here).To compensate for excessive heat input, liquefied gas is introduced directly into the gas in the gas supply line 8 at the introduction device 15, preferentially cooling it to the desired temperature. This is possible with high precision thanks to the temperature control of the control valve 16; the device 1 thus enables very precise temperature control of the vaporized gas in the gas supply line 8. Furthermore, within the scope of the invention, it is by no means necessary for the gas stream flowing through the gas supply line 8 to have previously been generated by vaporizing a liquefied gas; rather, the gas flowing in the gas supply line 8 can also originate from other sources and be passed through the gas supply line 8 as the gas to be tempered.In this case, there is no flow connection between the extraction line 3 and the gas supply line 8, and there is also no evaporator unit 4, but the liquefied gas from the storage tank 2, which is preferably gas of the same type as that fed through the gas supply line 8, is fed via the liquid supply line 13 into the gas supply line 8 for the purpose of tempering the gas in the gas supply line 8.

[0036] The inventive feed system 15 of the device 1 shown in Fig. 2a / 2b and Fig. 3 is in a cylindrical section of the gas supply line 8. Fig. 2b shows the feed system from Fig. 2a in a view rotated by 90° about a longitudinal axis 19 of the gas supply line 8. As can be seen in particular in Fig. 2a, the liquid supply line 13 opens out at an L-shaped end section, one leg of which is arranged inside, preferably concentrically, in the gas supply line 8 and is equipped with a nozzle section 18. The nozzle section 18 protrudes from the end section of the liquid supply line 13 opposite to the flow direction 20 of the gas flow in the gas supply line 8, indicated by an arrow, and has a plurality of flow openings opening out axially and / or radially into the gas supply line 8.For example, the nozzle section 18 has a spray nozzle provided with corresponding openings or a sintered body 21 made of metal or ceramic, which enables a very fine distribution of the liquefied gas in the gas flowing through the gas supply line 8.

[0037] In order to ensure the fastest possible mixing of the evaporating gas supplied from the liquid feed line 13 with the gas flow guided through the gas feed line 8, a plurality of flow bodies 22a, 22b, 22c, 22d are arranged within the gas feed line 8 at the level of the nozzle section 18. The flow bodies 22a, 22b, 22c, 22d are each flat, approximately semicircular disc-shaped baffles, which are fastened with their arc-shaped edge section to the inner wall of the cylindrical gas feed line 8 and extend with their linear edge section within the gas feed line 8 almost to the outer wall of the nozzle section 18, wherein they are preferably arranged obliquely, inclined at an angle of 30° to 75° with respect to the flow direction 20.In the embodiment shown here, the flow bodies 22a, 22b; 22c, 22d are arranged in pairs symmetrically to one another, wherein the flow bodies 22c, 22d - viewed in the flow direction 20 - are arranged in the gas supply line 8 at a distance behind the flow bodies 22a, 22b and rotated by an angle of 90° about the longitudinal axis 19.

[0038] The arrangement of the flow bodies 22a, 22b, 22c, 22d shown here has the following consequences: Firstly, due to the constrictions of the flow cross-section downstream of the flow body pairs 22a, 22b; 22c, 22d, turbulence occurs in the gas flow, which promotes the intimate mixing of the supplied liquid gas with the surrounding gas flow. This results in a fine distribution of the liquefied gas in the flow of the vaporized gas, so that a gas with a largely homogeneous temperature is already present at the measuring device 17. Secondly, the gas flowing through the gas supply line 8 is directed toward the nozzle section 18, whereby part of the heat content of the gas is transferred to the nozzle body 18, which is cooled by the liquid gas. Furthermore, this arrangement of the flow bodies 22a, 22b, 22c, 22d prevents any liquid gas from accumulating at the bottom of the gas supply line 8 and flowing out through the gas supply line 8.

[0039] Furthermore, if a sufficiently long nozzle section 18 is selected, the sequence of flow bodies 22a, 22b, 22c, 22d described here can also be repeated several times in the gas supply line 8, although this is not shown for reasons of clarity. Furthermore, the flow bodies 22a, 22b, 22c, 22d can also be arranged in the gas supply line 8 in a different manner than shown here. For example, the flow bodies 22a, 22b, 22c, 22d can be arranged offset from one another in the longitudinal direction, instead of the paired arrangement shown here. Of course, more or fewer flow bodies 22a, 22b, 22c, 22d than the four shown here can also be provided. List of reference symbols:

[0040] 1 device

[0041] 2 tanks

[0042] 3 Withdrawal line

[0043] 4 Evaporator unit

[0044] 5 heat exchangers

[0045] 6 Cooling circuit

[0046] 7 Heat exchanger surface

[0047] 8 Gas supply line

[0048] 9

[0049] 10 air evaporators

[0050] 11 Control valve

[0051] 12 Sensor

[0052] 13 Liquid supply line

[0053] 14 consumers

[0054] 15 Entry setup

[0055] 16 Control valve

[0056] 17 Measuring device

[0057] 18 Nozzle section

[0058] 19 Longitudinal axis

[0059] 20 Flow direction

[0060] 21 sintered bodies

[0061] 22a, 22b, 22c, 22d flow bodies

Claims

Patent claims 1. Device for generating a tempered, cold gas stream, with a gas supply line (8) for passing a gas stream and a liquid supply line (13) connected to a storage tank (2) for cold-liquefied gas, which liquid supply line opens into the gas supply line (8) at an inlet device (15) with a nozzle section (18) arranged within the gas supply line (8), characterized in that the gas supply line (8) is equipped in the region of the nozzle section (18) with flow means (22a, 22b, 22c, 22d) for generating a turbulent flow in the gas stream guided through the gas supply line (8).

2. Device according to claim 1, characterized in that baffles are provided as flow means (22a, 22b, 22c, 22d) which extend from at least a partial section of the inner wall of the gas supply line (8) to at least approximately an outer surface of the nozzle section (18).

3. Device according to claim 2, characterized in that the deflection plates are arranged in the gas supply line (8) at an angle relative to the flow direction of the gas in the gas supply line (8).

4. Device according to one of the preceding claims, characterized in that in the gas supply line (8), along the nozzle section (18), a plurality of flow means (22a, 22b, 22c, 22d) are arranged one behind the other in the flow direction of the gas.

5. Device according to one of the preceding claims, characterized in that two flow means (22a, 22b; 22c, 22d) are arranged symmetrically opposite one another on the nozzle section (18). Device according to claim 5, characterized in that at least two pairs of flow means (22a, 22b; 22c, 22d) are arranged one behind the other in the gas supply line (8), wherein the respective rear pair is arranged in the gas supply line (8) rotated relative to the respective front pair by a predetermined angle about a longitudinal axis (19) of the gas supply line (8). Device according to one of the preceding claims, characterized in that the nozzle section (18) has a porous body (21) made of sintered metal or sintered ceramic. Device according to one of the preceding claims, characterized in that the nozzle section (18) of the liquid supply line (13) is aligned within the gas supply line (8) in such a way that the liquefied gas flows into its interior in countercurrent to the flow of gas in the gas supply line (8).Device according to one of the preceding claims, characterized in that the gas supply line (8) is connected to the storage tank (2) via a heat exchanger (5) and / or evaporator (10) integrated into the gas supply line (8). Device according to one of the preceding claims, characterized by an automatic control system (16) by means of which the supply of liquefied gas mixture from the liquid supply line (13) into the gas stream guided through the gas supply line (8) can be controlled according to measured or predetermined parameters.

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