FR2685066A1 - LYOPHILIZATION DEVICE. - Google Patents

Abstract

The invention relates to a freeze-drying device of the type comprising two contiguous enclosures, one primary (1) which comprises shelves (5) where the products to be freeze-dried are stored, the other secondary (2) where the trap (6); it comprises a temperature regulation pipe in which a single coolant circulates, this circuit comprising at least two independent parallel loops, one primary (7) supplying the trap, the other secondary (8) supplying the shelves, each being temperature-controlled by an independent heat and / or cold production unit (15, 16): thus the device only comprises a single heat transfer fluid regulating the temperatures of the trap and the shelves.

Description

LYOPHILIZATION DEVICE

  The invention relates to a lyophilization device. Lyophilization devices are installations intended to dry products, generally organic, by sublimation at very low

  temperature and very low pressure.

  Freeze-dryers are devices comprising two enclosures: a first in which the products to be treated are arranged, and next to a second in which is arranged a member called a trap, intended to receive the water coming from the products The installation further comprises a set of vacuum and cold generating apparatuses and circulation pumps for heat transfer fluids which bring the shelves and the spies to temperatures

  determined causing sublimation.

  In known installations, the temperatures in the chambers are regulated separately by two independent heat and / or cold production circuits. The main chamber, where the products are stored, is crossed by a first circuit supplied with a refrigerating liquid such as that marketed under the name "Freon" and regulated in temperature by a cold and hot production center so as to cool the shelves and freeze the product, then heat them to bring the product to primary freeze-drying temperatures (approximately 20 'C) and secondary (about 30' C) The secondary enclosure where the trap is located is crossed by a second circuit supplied by a silicone liquid and regulated in temperature by a plurality of power stations arranged in parallel, each comprising in known manner a freon condenser and exchanger The choice of different refrigerants is due mainly ment to the fact that the performances requested from the circuits are different: the first circuit must both go down to a very low temperature (around -45 to -50 C for freezing) but for a short time, and high (+ 30 'C ) while the second must only ensure a very low temperature (around -50 to -70 ° C) and this

for several hours.

  The advantage of such a device is that it is possible to choose refrigeration devices that precisely meet the specific working conditions and offer an optimal performance ratio. The major drawback is that the first circuit is direct expansion and it is difficult to properly control the heat exchange in the first enclosure, that is to say ultimately the

lyophilization.

  The invention aims to solve this drawback and to propose a device for regulating

  very precise heat production.

  The subject of the invention is a freeze-drying device of the type comprising two contiguous enclosures, the primary one comprising shelves where the products to be freeze-dried are stored, the other secondary where the trap is located, characterized in that it comprises a temperature regulation pipe in which a single heat transfer liquid circulates, this circuit comprising at least two independent parallel loops, one primary supplying the trap, the other secondary supplying the shelves, each being temperature controlled by a central

  independent heat and / or cold production.

  The device according to the invention is also remarkable for the following characteristics: the device comprises a bypass from the primary loop, which feeds the shelves, this bypass being or not put into service according to steps 0 O of the treatment by means of valves ; the secondary loop is regulated in temperature by a central production of cold and heat; the secondary loop includes an extension which feeds the trap, this extension being able to be put into service or not according to the stages of the treatment; the trap's cold production center is located on the primary loop and includes, in parallel,

  a plurality of refrigeration units.

  In order to better understand the invention, a non-limiting example of the device according to the invention has been illustrated in the accompanying drawing: FIG. 1 is a simplified diagram of a first embodiment of the invention, FIG. 2 is a variant of realization of the invention. Figures 3 a, 3 b, 3 c illustrate the three main modes of operation of the device according to

the invention.

  In the drawing we see that the freeze-drying device mainly comprises two enclosures, the primary enclosure 1 comprising the shelves 5 on which the products to be dried are placed, and the secondary enclosure 2 o is the trap 6 on which the water contained in the products must migrate; enclosures 1 and 2 communicate via tubing 3 controlled by a

valve 4.

  According to the invention the device comprises a main temperature regulation pipe 7 or primary loop forming a closed circuit and provided with a circulation pump 14 In this pipe circulates a

  heat transfer liquid, in the example a silicone liquid.

  This primary loop 7 feeds the trap through a

bypass 9.

  Parallel to the primary loop 7 the device comprises a secondary loop 8 which feeds the shelves and in which the same heat transfer fluid circulates This secondary loop is connected to the primary loop 7 by two parallel inlet 20 and outlet 21 pipes controlled by valves 10 and 12 so as to supply the shelves from the primary loop or, on the contrary to completely isolate them from said primary loop 7 The secondary loop includes a circulation pump 13 allowing the heat transfer fluid to circulate in the shelves independently of the fluid finding in

the main line.

  Each pipe includes a heat and / or cold production unit: the primary loop passes through a cold production unit 16, the secondary loop passes through a heat and cold production unit which, depending on the treatment phase, cools or heats the liquid. In the variant of FIG. 2, the primary loop 7 comprises in parallel a series of power stations 16 for refrigeration production. This arrangement makes it possible both to remedy untimely damage to a power station, during treatment and to have greater flexibility.

power.

  The secondary loop 8 has an extension 81 parallel to the first 8 in the trapping enclosure, this extension being intended for heating the trap to discharge its water, and for cooling the trap

after sterilization.

  The device operates in the following manner (in FIG. 3, the parts in strong lines are the active circuit elements): 1) Phase 1: freezing of the product (FIG. 3 a): the trap is isolated by closing the communication between the speakers 1 and 2 and isolating the branch 9; the circulation pump 13 and the thermal power station 15 are isolated from the secondary loop 8 and the shelves are supplied with cold fluid from the

  , primary loop 7 (by opening valves 10 and 12).

  2) Lyophilization (FIG. 3 b): When the freezing is complete, the valves 10 and 12 are closed: the secondary loop is isolated from the primary loop; and the central heating unit 15 ′ and the circulation pump 13 are started, while the trap is

  fed by the circulation of the fluid in the bypass 9.

  3) Cooling after sterilization (Figure 3 c): Between two consecutive treatments, the freeze dryer must be hot sterilized The speakers are brought to high temperature by any known means In order to avoid too long a cooling time and any thermal shock with the fluid at very low temperature of the primary loop we use the fluid of the secondary loop for cooling: we isolate the trap of the primary loop and we feed it by the extension 8 'of the secondary loop The fluid of the secondary loop 8, 8 'is then cooled by the cooling unit "As we can see the temperatures of the trap and the shelves are regulated with a single and same fluid which circulates in a single circuit, provided with two temperature control units This arrangement provides the following advantages: the temperature regulation of the shelves is more precise since it is possible to determine with exactitude the temperatures are entering and leaving the trap and the shelves and controlling the flow rates; the speed of sublimation of the water can be controlled, this speed depending on the temperature of the shelves; after their preparative sterilization, the cooling of the shelves and the trap is faster and more efficient; the cooling of the product, at the end of secondary lyophilization, can be very rapid or even instantaneous by mixing the liquids of the primary loops

and secondary.

  In addition, by eliminating the long Freon loop which usually feeds the shelves, the resulting problems are also eliminated, in particular the difficult oil returns, implantation constraints.

and the cost in Freon.

Claims (4)

  1 Freeze-drying device of the type comprising two contiguous enclosures, one primary (1) which includes shelves (5) where the products to be freeze-dried are stored, the other secondary (2) where the trap (6) is located , characterized in that it comprises a temperature regulation pipe in which a single heat transfer liquid circulates, this circuit comprising at least two independent parallel loops, one primary (7) feeding the trap, the other secondary (8) supplying the shelves, each being temperature controlled by an independent heat and / or cold production unit (15, 16).  2 lyophilization device according to claim 1 characterized in that it comprises a bypass (20, 21) from the primary loop (7), which feeds the shelves, this bypass being or not put into service according to the stages of treatment by means of valves (10, 12).   3 lyophilization device according to claim 1 characterized in that the secondary loop (8) is temperature controlled by a central   production of cold (15 ") and hot (15 ').   4 lyophilization device according to claim 1 characterized in that the secondary loop (8) has an extension (8 ') which feeds the trap (6), this extension can be put into service or not according to the stages of treatment.   Lyophilization device according to claim 1 characterized in that the central (16) for producing cold from the trap (6) is arranged on the primary loop (7) and comprises, in parallel, a plurality of refrigeration units.