DEVICE FOR GENERATING AND STORING CARBON DIOXIDE SNOW

Abstract

The invention relates to a device for generating and storing carbon dioxid snow, comprising a container into which an expansion nozzle connected to a supply line for liquid carbon dioxide and a gas extraction line open, a removal device for removing carbon dioxide snow out of the container, and a measuring device for detecting the fill level of the carbon dioxide snow in the container. According to the invention, the measuring device comprises a photoelectric sensor unit which is arranged at a vertical distance to the base of the container and which comprises a light-emitting transmitter and a light-sensitive receiver.

Claims

1. A device for generating and storing carbon dioxide snow, the device comprising: a container into which a snow horn connected to a supply line for liquid carbon dioxide and a gas extraction line opens; and a measuring device for detecting the fill level of carbon dioxide snow in the container; wherein the measuring device comprises a photoelectric sensor unit that is arranged vertically spaced apart from the base of the container and that has a light-emitting transmitter and a light-sensitive receiver.

2. The device as claimed in claim 1, wherein the transmitter and receiver of the photoelectric sensor unit are arranged in a common housing.

3. The device as claimed in claim 1, wherein the photoelectric sensor unit operates using light in the optical or infrared frequency range.

4. The device as claimed in claim 1, wherein the transmitter and receiver of the photoelectric sensor unit are arranged in a lateral wall of the container in such a way that the transmitter and receiver are arranged with a front surface in alignment with an inner wall of the container.

5. The device as claimed in claim 1, wherein a plurality of photoelectric sensor units are arranged vertically spaced apart from one another in the container.

6. The device as claimed claim 1, further comprising a removal device that has means for removing a defined amount of carbon dioxide snow from the container at regular time intervals.

7. The device as claimed in claim 6, wherein the photoelectric sensor unit has a data connection to a control unit, by means of which the inflow of liquid carbon dioxide in the supply line and/or the removal of carbon dioxide from the container at the removal device can be controlled depending on a detected fill level of carbon dioxide snow in the container.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0016] An exemplary embodiment of the invention shall be discussed in more detail on the basis of the drawing. The single drawing (FIG. 1) schematically shows a device according to the invention in longitudinal section.

DETAILED DESCRIPTION

[0017] The device 1 shown in FIG. 1 comprises a thermally well-insulated container 2 in the form of an upright cylinder having for example a rectangular cross section, into the upper end face—seen geodetically—of which open a snow horn 3 and a gas extraction line 4. The snow horn 3 is connected to a supply line 5 for liquid carbon dioxide that in turn is connected to a tank (not shown here) in which the carbon dioxide is stocked at a pressure of for example 15 bar. The snow horn 3 comprises an expansion nozzle 6 that also forms the end of the supply line 5, and a diffuser 7 that projects into the interior of the container 2. Arranged at the base of the container 2 is a removal device 8 (not discussed in any more detail here) for removing carbon dioxide snow. By way of example, said removal device is a removal device that permits the removal of defined amounts of carbon dioxide snow at regular time intervals, as described for example in EP 3 222 946 A1 or WO 2017/167620 A1, to which reference is expressly made here. By way of example, the removal device 8 is configured in such a way that, during operation thereof, an amount of carbon dioxide snow that is the same in each case is expelled from the container 2 at time intervals, that are the same in each case, of between 1 s and 30 s, for example every 5 s to 10 s.

[0018] A photoelectric sensor unit 10 is arranged in a side wall of the container 2, vertically spaced apart from the base of the container 2. The photoelectric sensor unit 10 comprises a transmitter 11 and a receiver 12 that, in the exemplary embodiment, are accommodated in a common housing 9. The transmitter 11 is able to emit light of a specific frequency or of a specific frequency range, for example a frequency or a frequency range in the optical or infrared spectrum. The receiver is able to detect light of the same frequency or of the same frequency range and convert it into an electronic signal. The transmitter 11 and receiver 12 have a data connection to a control unit 13, from which the emission of light at the transmitter 11 can be prompted and in which electronic data from the receiver 12 can be processed. The control unit 13 also has a data connection to the removal device 8 and to a valve 14 in the supply line 5 by means of which the inflow of liquid carbon dioxide through the supply line 5 can be controlled in accordance with a control command transmitted by the control unit 13 and be adjusted for example to the amount of carbon dioxide snow to be removed from the container 2 per unit of time.

[0019] The sensor unit 10 is installed in the wall of the container 2 in such a way that a front surface 15, 16 of the transmitter 11 and receiver 12 is in each case essentially flush with the inner wall 17 of the container 2. The front surfaces 15, 16 may be part of the respective electronic component, that is to say the transmitter 11 or receiver 12, itself, or may be formed by a pane made of a transparent material (not shown here) that separates the sensor unit 10 from the interior of the container 2.

[0020] Electric heating elements 18 mounted in the inner wall 17 of the container 2 prevent carbon dioxide snow from caking on the inner wall 17. In order to ensure the functionality of the sensor unit 10, it is advisable to also provide such heating elements 18 in the vicinity of the sensor unit 10.

[0021] During operation of the device 1, liquid carbon dioxide at a pressure of for example 15 bar is introduced via the supply line 5 and expanded at the expansion nozzle 6. The liquid carbon dioxide changes here into a mixture of carbon dioxide gas and carbon dioxide snow. While the carbon dioxide gas is discharged via the gas extraction line 4, the snow generated falls downward in the container 2 and gradually fills the container 2 from the bottom upward. At the same time as the supply of carbon dioxide, the transmitter 11 is prompted by the control unit 13 to emit light into the interior of the container 2.

[0022] Whilst the fill level of the carbon dioxide snow collecting in the container 2 has not yet reached the level of the sensor unit 10, that is to say for example the container is only filled up to a first fill level 19, there is a turbulently flowing mixture of carbon dioxide snow and carbon dioxide gas at the level of the sensor unit 10 while the carbon dioxide is being supplied. Light emitted by the transmitter 11 into the interior of the container 2 is diffusely reflected by this mixture and a small portion thereof is captured by the receiver 12. The receiver 12 sends a corresponding signal to the control unit 13, said signal indicating to said control unit that the fill level of the snow has not yet reached the level of the sensor unit 10. However, if the fill level of the carbon dioxide snow in the container 2 surpasses the level of the sensor unit 10, that is to say for example it is at a second fill level 20, the light emitted by the transmitter 11 is no longer able to penetrate the layer of snow immediately in front of the transmitter 11 and only very little, if any, thereof reaches the receiver 12. A corresponding electronic signal is output by the receiver 12 to the control unit 13, said signal prompting said control unit, for instance in accordance with a specified program, to output further control commands, for example to close or throttle the valve 14 in the supply line 5 and/or to activate the removal device 8 to remove carbon dioxide.

LIST OF REFERENCE SIGNS:

[0023] 1 Device

[0024] 2 Container

[0025] 3 Snow horn

[0026] 4 Gas extraction line

[0027] 5 Supply line for liquid carbon dioxide

[0028] 6 Expansion nozzle

[0029] 7 Diffuser

[0030] 8 Removal device

[0031] 9 Housing

[0032] 10 Photoelectric sensor unit

[0033] 11 Transmitter

[0034] 12 Receiver

[0035] 13 Control unit

[0036] 14 Valve

[0037] 15 Front surface (of the transmitter)

[0038] 16 Front surface (of the receiver)

[0039] 17 Inner wall

[0040] 18 Heating element

[0041] 19 First fill level

[0042] 20 Second fill level