Classifications

• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
  • A23L3/00—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
  • A23L3/36—Freezing; Subsequent thawing; Cooling
  • A23L3/37—Freezing; Subsequent thawing; Cooling with addition of or treatment with chemicals
  • A23L3/375—Freezing; Subsequent thawing; Cooling with addition of or treatment with chemicals with direct contact between the food and the chemical, e.g. liquid nitrogen, at cryogenic temperature
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
  • B01J2/02—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops
  • B01J2/06—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops in a liquid medium
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25C—PRODUCING, WORKING OR HANDLING ICE
  • F25C1/00—Producing ice
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
  • F25D3/00—Devices using other cold materials; Devices using cold-storage bodies
  • F25D3/10—Devices using other cold materials; Devices using cold-storage bodies using liquefied gases, e.g. liquid air

Definitions

• the invention relates to a device and a process for the pellet-freezing of liquid or flowable substances in a liquid coolant, in particular a cryogenic liquid, such as a liquefied gas, into which the substance to be frozen is guided directly in order to be frozen fully.
• a liquid coolant in particular a cryogenic liquid, such as a liquefied gas
• the purpose of such devices and processes is to freeze liquid substances, such as for example foodstuffs or additives, for the preparation of foodstuffs, by immersing them directly in a bath of coolant or a flow of coolant.
• the flow of coolant is guided through an open pelletizing conduit, at the start of which the substance is introduced, for example by means of a dropping device.
• frozen granules known as pellets, are formed and are separated again from the flow of coolant by means of suitable separating devices.
• One of the problems with pelletizing is that, after they have been immersed in the flow of coolant, the pellets run the risk of remaining stuck in the conduit, and for this reason the devices have to be cleaned regularly.
• EP 0,844,018 A2 has described a pelletizing device in which drops of the substance which is to be frozen are introduced at a point in the freezing section through which coolant flows at which a laminar flow prevails. This prevents the possibility of the pellets remaining stuck together or to the conduit as a result of turbulent flow of the coolant. This is because a turbulent flow may convey relatively large pellets onto the side walls or the base of the pelletizing conduit, where under certain circumstances they may remain stuck, interfering with the flow of coolant.
• a drawback of this device is that, despite the laminar flow, pellets may still continue to stick if, for example, the volume of the flow of coolant decreases or increases.
• the object of the present invention is to provide a pellet-freezing device and process which prevent pellets from sticking in the freezing section and enable continuous, undisrupted production of pellets to be achieved.
• This object is achieved by means of a device according to the features of Claim 1 and by means of a process according to the features described in Claim 7.
• Advantageous configurations and refinements form the subject matter of the subclaims.
• a coolant outlet trough is provided, which is connected upstream of the pelletizing conduit, i.e.
• the freezing section has an outlet.
• the cross section of the outlet is preferably of the same size as the conduit.
• the outlet trough is connected to the conveyor device via a conveyor line in order to be filled with coolant, and means are provided for controlling the coolant level in the trough. This ensures that the flow of coolant remains constant in the pelletizing conduit irrespective of any disruptive influences from the pump or other components of the device. Due to the upstream coolant outlet trough, evaporation of coolant in the device or variation in the level in the container sump of the device have no influence on the flow of coolant generated in the freezing section. The trough with a constant coolant level consequently serves as a "buffer" between the freezing section and the remainder of the coolant circuit in the device.
• the outlet of the coolant outlet trough can be closed adjustably by means of a slide valve.
• the coolant flow rate in the freezing section can thus also be adapted to different pellet sizes and substances of different weights, depending on the required immersion depth of the drops, preventing pellets from sticking. In this way, the coolant and energy consumption can be optimized.
• the coolant outlet trough forms an upper air chamber which is closed off from the interior of the vessel of the device and is connected to a suction pipe. In this way, it is possible to suck out evaporated coolant. Consequently, the pressure in the air chamber is constant, ensuring that there are no pressure influences having an adverse effect on the flow of coolant in the freezing section in this respect.
• a trough overflow which is connected to a return line is provided as the level- control means.
• the return line is simultaneously used to cool the conveyed coolant, by being guided along the conveyor line. The coolant which has been heated slightly by the pumping operation is thus cooled by the coolant flowing back. This saves energy and coolant.
• the volumetric flow rate conveyed by the conveyor device is 1/3 greater than the coolant flow rate in the freezing section. It has been found that, if this level of excess coolant is conveyed into the outlet trough, the volumetric flow rate of coolant in the freezing zone remains constant with the greatest possible level of reliability.
• the pellet-freezing process according to the invention in which a liquid substance is introduced into a freezing section containing coolant and the coolant is fed back to the circuit from the vessel in order to be reused, contains the following steps: filling a coolant outlet trough with a constant conveyed volumetric flow rate which is greater than the coolant flow rate required in the freezing section, controlling the trough level to a constant level, and allowing a constant coolant flow rate out into the freezing section.
• This ensures a uniform coolant flow rate in the freezing section, ensures that it is impossible for any pellets to stick to the conduit walls as a result of irregularity in the coolant volumetric flow rate, and enables the production of pellets to proceed continuously, without regular cleaning breaks .
• evaporated coolant is sucked out. A build- up of pressure caused by vapour is avoided, and there is no consequent adverse effect on the flow of coolant.
• FIG. 1 shows a simplified side view of a pellet-freezing device.
• a pump is provided as a conveyor device 2, by means of which the coolant 13 is conveyed upwards out of the bottom of the vessel into the pelletizing conduit 3.
• the introduction device 4 by means of which a substance which is to be processed can be introduced in drops into the flow of coolant in the pelletizing conduit 3, is provided above the conduit 3.
• the coolant outlet trough 5, which is filled with a constant amount of coolant 13, is provided at the top end of the obliquely arranged pelletizing conduit 3. Via the outlet 6 of the trough 5, a constant amount of coolant 13 flows into the freezing section of the conduit 3.
• the size of the outlet opening 6 can be adjusted by means of a slide valve 9. As a result, the flow of coolant can be adapted according to requirements.
• the amount and flow velocity of the flow of coolant is constant, with the result that losses in the production of pellets are as far as possible avoided.
• the constant quantity of coolant in the trough 5 is achieved by means of the conveyor device 2 and an overflow 11 from the trough 5.
• the conveyed volumetric flow rate is always greater than the volumetric flow rate of coolant removed at the outlet 6. From the overflow 11, a return line 12 leads down into the bottom of the vessel 1, where the surplus coolant 13 is collected.
• the return line 12 is in this case guided around the conveyor line 7, so that a type of double tube is formed, enabling the coolant which flows back down to cool the coolant in the conveyor line 7, which has been heated slightly by the pumping operation.
• the return line 12 may also open directly into the sump of the vessel 1 without being arranged on the conveyor line 7 for cooling purposes.
• a suction pipe 10 for sucking out coolant which has evaporated in the coolant outlet trough 5 is provided above the trough 5.
• the pelletizing vessel 1 itself is also provided with a suction pipe 10 on its top side. A pressure increase in the trough 5, which leads to an increase in the coolant volumetric flow rate in the freezing section, is thus avoided.
• the invention may, as a further variant, also be designed without suction pipes 10. List of reference numerals

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Nutrition Science (AREA)
• Health & Medical Sciences (AREA)
• Organic Chemistry (AREA)
• Food Science & Technology (AREA)
• Polymers & Plastics (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=7634774

Family Applications (1)

Country Status (4)

Cited By (3)

Families Citing this family (1)

Citations (4)

Family Cites Families (3)

• 2000
  • 2000-03-15 DE DE2000112550 patent/DE10012550B4/de not_active Expired - Fee Related
• 2001
  • 2001-03-13 AU AU2001260161A patent/AU2001260161A1/en not_active Abandoned
  • 2001-03-13 WO PCT/EP2001/003487 patent/WO2001068231A1/en active Application Filing
  • 2001-03-14 AR ARP010101194A patent/AR027660A1/es unknown

Patent Citations (4)

Also Published As

Similar Documents

Legal Events