Freeze-dryer and method for freeze-drying

Abstract

The invention relates to a freeze-dryer comprising a freeze-drying chamber having an inlet for allowing introduction of material to be dried into the freeze-drying chamber and configured to be at least partially evacuated, and a vacuum source in fluid communication with the drying chamber and configured to at least partially evacuate the freeze-drying chamber, wherein a vacuum fluid path is defined between the freeze-drying chamber and the vacuum source, wherein the freeze-dryer further comprises a collection filter configured to collect dried material from the freeze-drying chamber, the collection filter being arranged outside the freeze-drying chamber and within the vacuum fluid path between the freeze-drying chamber and the vacuum source.

Description

Technical Field

[0001] The present invention relates to a freeze dryer having a freeze-drying chamber and a vacuum source, the freeze-drying chamber having an inlet for allowing material to be dried to be introduced into the freeze-drying chamber and configured to be at least partially emptied, and the vacuum source being in fluid communication with the drying chamber and configured to at least partially empty the freeze-drying chamber, wherein a vacuum fluid path is defined between the freeze-drying chamber and the vacuum source. Background Technology

[0002] Such freeze dryers are known, for example, from EP 1 601 919 B1, which discloses a method and apparatus for freeze-drying solutions and liquids containing solid substances, wherein a container having a downwardly conical shape is used, the interior of which has a rotating mixing member that moves along the wall of the container with a small gap.

[0003] A known drawback of freeze dryers is that the dried portion of the material to be dried is retained within the freeze-drying chamber while the remaining material dries. Therefore, all products are processed continuously throughout the drying process due to the action of the rotating mixing components. This is detrimental to applications where sensitivity to shear forces is critical, such as in the freeze-drying of probiotics and other live cells, or in the freeze-drying of spherical PLGA-based formulations.

[0004] Another drawback may be that the available heat transfer area is underutilized as the product volume decreases continuously during freeze-drying. Summary of the Invention

[0005] The object of the present invention is to improve or eliminate one or more disadvantages of known freeze dryers, and to provide an improved freeze dryer or at least an alternative freeze dryer.

[0006] According to a first aspect, the present invention provides a freeze dryer, comprising:

[0007] A freeze-drying chamber having an inlet for allowing the material to be dried to be introduced into the freeze-drying chamber and configured to be at least partially evacuated; and

[0008] A vacuum source, which is in fluid communication with the drying chamber and configured to at least partially evacuate the freeze-drying chamber, wherein a vacuum fluid path is defined between the freeze-drying chamber and the vacuum source.

[0009] The freeze dryer also includes a material collector configured to collect dried material from the freeze drying chamber. The material collector is arranged outside the freeze drying chamber and within the vacuum fluid path between the freeze drying chamber and the vacuum source.

[0010] During use, the vacuum source at least partially empties the freeze-drying chamber, and during the freezing of the material to be dried, fine ice particles are formed from the initial material. Once the pressure is low enough, the formed ice particles begin to sublimate. As sublimation proceeds, a vapor stream exists between the freeze-drying chamber and the vacuum source, passing through the material collector. As the vapor stream flows toward the vacuum source, the size of the individual ice particles decreases, resulting in the release of powdery dust from the material. The powdery dust flows toward the material collector, where it is collected from the vapor stream. As a result, the vapor stream downstream of the material collector is essentially free of powdery dust, as the powdery dust is collected by the material collector. By removing the material to be dried from the freeze-drying chamber after drying, the processing time on the dried material is minimized, thereby advantageously reducing or ideally eliminating the risk of damage to the dried material due to the shear forces applied thereto.

[0011] Another advantage is that, since the material is removed from the freeze-drying chamber during drying, the remaining material in the chamber remains wet. Therefore, the dried material no longer occupies a portion of the heat transfer area present within the freeze-drying chamber, thus improving the efficiency of utilizing the available heat transfer area.

[0012] In one embodiment, a material collector is arranged next to and / or near the freeze-drying chamber. As the powdery dust from the dried material is collected by the material collector, the dust may fall downwards within the collector due to gravity, for example, towards the bottom of the collector. An advantage of this embodiment is that the collection of the collected material from the material collector can be performed relatively simply.

[0013] In one embodiment, the material collector includes a collector housing and a collecting device. The collector housing has an inlet in fluid communication with a freeze-drying chamber, a vacuum outlet in fluid communication with a vacuum source, and a collector fluid path between the inlet and the outlet. The collecting device is disposed between the inlet and the outlet, dividing the collector fluid path into a first path portion downstream of the collecting device and a second path portion upstream of the collecting device. In another embodiment, the collecting device includes a collecting filter disposed between the inlet and the outlet, dividing the collector fluid path into a first path portion downstream of the collecting filter and a second path portion upstream of the collecting filter. This collecting filter is typically used to filter dust from the vapor stream, and many types of collecting filters are available. Therefore, a suitable collecting filter can be advantageously selected based on the material to be dried.

[0014] In one embodiment, the collector housing has a material outlet in fluid communication with a first or second path portion of the collector fluid path and is configured to allow material collected by the collecting device to exit the collecting device. In one embodiment, the collector housing has a bottom, wherein the material outlet is disposed at or near the bottom of the collector housing. During use, as dusty particles are removed from the vapor stream through the collecting device of the material collector, the collected dusty particles can fall downward toward the material outlet and exit the material collector via the material outlet, so that the collected dusty particles can be advantageously received below the material collector.

[0015] In one embodiment, the collector housing has a double-jacketed wall configured to receive heating fluid for heating fluid flowing through the collector fluid path and / or dried material collected within the material collector. Due to this double-jacketed wall, further drying of the collected powdery dust can be carried out within the material collector.

[0016] In one embodiment, the freeze dryer includes a material collection receiver configured to receive material collected by a material collector and disposed at or near the material collector. In another embodiment, the material collection receiver has a receiver body defining a receiver chamber for receiving the collected material. In yet another embodiment, the material collection receiver is disposed at the material outlet to receive the collected material from the material collector when the collector housing has a material outlet in fluid communication with a first path portion of the collector's fluid path and is configured to allow material collected by the collecting device to exit the collecting device. During use, preventing the delivery of powdery dust from the freeze-drying chamber to the collected material and subsequently received in the material collection receiver from contacting the environment creates the possibility of performing an aseptic drying process.

[0017] In one embodiment, the material collection receiver is configured to heat the collected material received therein. Preferably, the receiver body of the material collection receiver has a double-jacketed wall configured to allow heating fluid to circulate therein. An advantage of this embodiment is that the collected powdery dust can be further dried when needed.

[0018] In one embodiment, the material collector is arranged at a first height, the freeze-drying chamber is arranged at a second height, and / or the material collector is located on top of and / or above the freeze-drying chamber. In another embodiment, the freeze dryer includes a valve arranged within a vacuum fluid path and between the freeze-drying chamber and the material collector, wherein the valve is configured to move between an open position for allowing fluid to flow from the freeze-drying chamber to the material collector, a closed position for preventing fluid from flowing from the freeze-drying chamber to the material collector, and / or an intermediate position for restricting fluid flow from the freeze-drying chamber to the material collector. An advantage of this embodiment is that, for example, the vapor flow toward the material collector can be stopped, restricted, or allowed at any desired point in time.

[0019] In one embodiment, the valve is also configured to temporarily retain material collected by the material collector when in the closed position. In another embodiment, the freeze dryer includes a fluid bypass conduit between the freeze-drying chamber and the material collector, and a bypass fluid path bypassing the valve between the freeze-drying chamber and the material collector. During use, the valve is intended for two purposes: firstly, to allow, prevent, or restrict the vapor flow; and secondly, to temporarily retain material collected by the material collector from the vapor flow. The valve and the bypass fluid bypass conduit advantageously allow the recirculation of minute ice particles during the sublimation phase. During freeze-drying, the valve between the material collector and the freeze-drying chamber is in the open position in the early stages of the freezing and sublimation phases, allowing the minute ice particles to recirculate back into the freeze-drying chamber instead of remaining in the material collector. Because the valve is in the open position, the minute ice particles fall back into the freeze-drying chamber under the influence of gravity. As freeze-drying continues, more powdery dust is released from the freeze-drying chamber, and the valve is closed. From that point onward, the released dust must travel with the vapor flow through a fluid bypass conduit to the material collector. The dust collected from the vapor flow falls onto a valve in the closed position, temporarily holding the collected dust. At the end of the freeze-drying process, the valve moves to its open position, allowing the dust held by the valve to be reintroduced into the freeze-drying chamber. Optionally, the reintroduced dust undergoes “secondary” drying and / or is removed from the freeze-drying chamber. This is advantageous because it utilizes the available heat transfer area more effectively.

[0020] In one embodiment, the freeze dryer further includes a purification inlet in fluid communication with a vacuum fluid path, preferably downstream of the material collector, wherein the purification inlet is configured to connect to a purification source to allow air pulses to be supplied to the material collector. When the material collector is used to collect powdery dust from the vapor flow, the material collector, such as its filter, may become clogged with the collected powdery dust. By supplying air pulses to the material collector, preferably in the opposite direction to the flow of the vapor flow, any powdery dust is blown out of the material collector, thereby advantageously preventing clogging of the material collector.

[0021] In one embodiment, the freeze dryer includes a generally conical container, preferably having a downwardly tapered shape, defining a freeze-drying chamber, and a stirring member arranged within the freeze-drying chamber and configured to stir the material introduced into the freeze-drying chamber. This stirring member advantageously prevents the material to be dried from freezing into solid ice masses.

[0022] In one embodiment, the generally conical container includes a cover for sealing the top of the freeze-drying chamber, wherein the cover and / or the generally conical container are provided with one or more nozzles having outlets oriented into the freeze-drying chamber and configured to connect to a gas source. During use, at the end of the freeze-drying process, material may remain in the freeze-drying chamber or at least partially deposited on the inner periphery of the freeze-drying chamber. By means of the nozzles penetrating into the freeze-drying chamber, gaseous emissions, such as air or nitrogen, can be introduced into the freeze-drying chamber intermittently, for example for short periods. As the freeze-drying chamber is at least partially emptied, the expansion of the gas introduced into the freeze-drying chamber causes the remaining material to be blown away, thereby advantageously increasing the likelihood of conveying the remaining material to a material collector.

[0023] In one embodiment, the substantially conical container includes a releasable outlet at its bottom, which is typically closed but can be opened.

[0024] In one embodiment, all components of the freeze dryer are arranged to be housed and / or connected to each other in a housed manner. In the context of this invention, the term "comprising" means encompassing the operations employed in the method of drying materials, and thus isolating these operations from the surrounding environment. Therefore, the operator does not need direct contact with the individual operations during operation.

[0025] According to a second aspect, the present invention provides a material collector for use in a freeze dryer according to a first aspect of the present invention.

[0026] According to a third aspect, the present invention provides a method for freeze-drying or sublimating a material to be dried using a freeze dryer, particularly a freeze dryer according to the first aspect of the present invention, wherein the method comprises the following steps:

[0027] - The material to be dried is introduced into the freeze-drying chamber of the freeze dryer; and

[0028] - By means of a vacuum source, at least partially evacuating the freeze-drying chamber, so as to reduce the pressure inside the freeze-drying chamber to a predetermined pressure level or below a predetermined pressure level.

[0029] The method further includes the step of collecting dried material from the freeze-drying chamber by means of a material collector disposed outside the freeze-drying chamber and within a fluid path between the freeze-drying chamber and a vacuum source.

[0030] This method has at least the same advantages as the freeze dryer described according to the first aspect of the invention.

[0031] In one embodiment, the method includes the step of lowering the temperature within the freeze-drying chamber to a temperature close to the freezing temperature of the material to be dried, preferably prior to the step of emptying the freeze-drying chamber. In the context of this patent application, "close to the freezing temperature" must be understood as a temperature slightly above or slightly below the freezing temperature.

[0032] In one embodiment, the method includes the step of introducing a gaseous emission, such as an intermittent gaseous emission, into the freeze-drying chamber, preferably at or near the end of the freeze-drying process.

[0033] In one embodiment, the method includes the step of preferably periodically providing backflush pulses on the material collector.

[0034] In one embodiment, the method includes the steps of reintroducing material collected by a material collector into the freeze-drying chamber at the end of the freeze-drying process, and the step of post-mixing the reintroduced material with the remaining material in the freeze-drying chamber.

[0035] In one embodiment, the material collector is disposed at a first height, and the freeze-drying chamber is disposed at a second height, and / or the material collector is located on top of and / or above the freeze-drying chamber. The freeze-dryer includes a valve disposed within a vacuum fluid path and between the freeze-drying chamber and the material collector, wherein the valve is configured to move between an open position allowing fluid to flow from the freeze-drying chamber to the material collector, a closed position preventing fluid from flowing from the freeze-drying chamber to the material collector, and / or an intermediate position restricting fluid flow from the freeze-drying chamber to the material collector, and wherein the freeze-dryer includes a fluid bypass conduit disposed between the freeze-drying chamber and the material collector, and a bypass fluid path bypassing the valve is provided between the freeze-drying chamber and the material collector. The method includes the following steps:

[0036] The valve is kept in the open position during freezing and the early stages of sublimation, allowing tiny ice particles to be recirculated back into the freeze-drying chamber.

[0037] As drying progresses, more dust is released from the freeze-drying chamber. At this point, the valve is moved to its closed position, forcing the released dust to move to the material collector via a bypass conduit; and

[0038] Alternatively, at the end or near the end of the drying process, the valve is moved to its open position so that the dust collected on the valve can be returned to the freeze-drying chamber.

[0039] The various aspects and features described and illustrated in this specification may be applied individually in any possible circumstances. These individual aspects, particularly those described in the appended dependent claims, may be the subject of a divisional patent application. Attached Figure Description

[0040] The invention will be described and illustrated based on exemplary embodiments shown in the accompanying drawings, in which:

[0041] Figure 1A and 1B Isometric views of a freeze dryer with a conical container and a material collector according to a first embodiment of the present invention are shown respectively. Figure 1A A cross-sectional view of the conical container along line IA-IA;

[0042] Figure 2A and 2B It shows Figure 1A Isometric view of the material collector and Figure 2A A cross-sectional view of the material collector along line IIA-IIA;

[0043] Figures 3A-3BAn isometric view of a freeze dryer with a conical container and a material collector according to another embodiment of the present invention is shown. Figure 3A A cross-sectional view of the conical container along line IIIA-IIIA. Detailed Implementation

[0044] The freeze dryer 1 according to the first embodiment of the present invention is as follows: Figure 1A As shown. The freeze dryer 1 includes a conical container 2 having a downwardly conical (conical) shape, within which a freeze-drying chamber 3 is defined. The conical container 2 has a conical container wall 10 having an open top side 11 and an open bottom side 12 opposite to the open top side 11. A top cover 13 is disposed at the open top side 11 of the conical container wall 10 for closing the open top side 11. The top cover 13 is secured to the open top side of the conical container wall 10 by means of a plurality of clamping screws 14. A releasable outlet 15 is disposed at the open bottom side 12 of the conical container wall 10 for closing the open bottom side 12. The releasable outlet 15 is configured to be normally closed but allow opening when needed. Figure 1B As shown, the conical container 2 includes a stirring member, specifically a stirring screw 16, for stirring the material introduced into the freeze-drying chamber 3. The stirring member is operatively connected to the drive 17 by means of a gearbox 18 and a gear assembly 19, as is known to those skilled in the art.

[0045] like Figure 1B As shown, the conical container wall 10 has a first compartment 20 and a second compartment 21, thereby forming a double-jacketed container wall 10, wherein the first compartment 20 and the second compartment 21 are arranged concentrically relative to each other. Each of the first compartment 20 and the second compartment 21 is configured to receive a heat exchange medium to cool and heat the contents of the freeze-drying chamber according to the stage during the freeze-drying process. The conical container wall 10 also includes an upper flange 22 for securing the top cover 13 to the conical container wall 10, and a lower flange 9 for securing the releasable outlet 15 to the conical container wall 10.

[0046] like Figure 1A and 1BAs further shown, the releasable outlet 15, for example a ball valve, is provided with an attachment flange 23, for example, for attaching a receiving container (not shown) to the freeze dryer 1. The releasable outlet 15 also has a handle 24 for moving the releasable outlet 15 between a closed position and an open position, in which the bottom side 12 of the opening of the conical container wall 10 is closed by the releasable outlet 15, and in the open position, the bottom side 12 of the opening of the conical container wall 10 is open, and material can exit the freeze-drying chamber 3. Such a releasable outlet 15 is known to those skilled in the art. Alternatively, the releasable outlet 15 can be pneumatically operated.

[0047] like Figure 1A As shown, the top cover 13 includes a generally circular top cover body 25 with a clamping flange 26 at its outer periphery. The clamping flange 26 is configured to receive a clamping screw 14 for clamping the top cover body 25 to the tapered container wall 10. On the upward-facing side of the top cover body 25, the top cover body 25 is provided with a plurality of attachment flanges 27, for example, for attaching sensors or freeze dryer accessories to the freeze dryer 1. In this embodiment, the illumination source 28, the vent valve 29, and the viewing mirror 30 are each attached to the top cover body 25 via a corresponding attachment flange 27 of the plurality of attachment flanges 27. The top cover body 25 also includes an outlet bus 31 having a fluid outlet channel extending therethrough and penetrating into the freeze-drying chamber 3. The outlet bus 31 is provided with a first connecting flange 32 at its end remote from the freeze-drying chamber 3. The first connecting flange 32 has a switch bracket 33 extending in a direction away from the first connecting flange 32 and having a safety switch 34 thereon.

[0048] The freeze dryer 1 also includes a vacuum source, such as a vacuum pump (not shown), which is operatively connected to the freeze-drying chamber 3, i.e., in fluid communication with the freeze-drying chamber 3. The vacuum source is configured to reduce the pressure inside the freeze-drying chamber to a predetermined pressure value, such as in the range of 5 mbar to 0.01 mbar, depending on the material / process conditions during use.

[0049] like Figure 1A As shown, the freeze dryer 1 also includes a material collector 40, which in Figure 2AThe following is shown in more detail. The material collector 40 includes a cylindrical tube 41 having a tube body 42 having an upper end 43 and a lower end 44 opposite to the upper end 43 in the longitudinal direction of the tube body 42. The tube body includes a first body portion 45, also referred to as the upper body portion, and a second body portion 46, also referred to as the lower body portion. The material collector 40 is provided with a fluid inlet conduit 46' disposed at the first body portion 45 and extending into the cylindrical tube 41. The fluid inlet conduit 46' has a first inlet conduit portion 47 disposed at the cylindrical tube 41 and oriented at an acute angle relative to the longitudinal direction of the cylindrical tube 41, such that fluid entering the cylindrical tube 41 is guided toward the second body portion 46. Furthermore, the fluid inlet conduit 46' has a second inlet conduit portion 48 disposed on the side of the first inlet conduit portion 47 opposite to the cylindrical tube 41, wherein the second inlet conduit portion 48 is formed as a bent conduit portion. The second inlet conduit portion 48 has a second connecting flange 49 at its end opposite to the first inlet conduit portion 47. The second connecting flange 49 has a magnet support 50 with a switching magnet 51 configured to cooperate with a safety switch 34 to determine whether the first connecting flange 32 and the second connecting flange 49 are correctly connected. The connection between the first connecting flange 32 and the second connecting flange 49 is maintained by means of a connecting clamp 35.

[0050] The material collector 40 also includes a filter holder 55 disposed at its upper end 43 within a cylindrical tube 41. The filter holder 55 has a cylindrical holder body 56 having a diameter substantially the same as that of the cylindrical tube 41. A retaining platform 57 is provided at the inner periphery of the cylindrical holder body 56, extending inwardly in a direction substantially transverse to the length direction of the cylindrical tube 41, and defining a filter through-hole 58 at its center. A clamping ring 59 is placed on top of the retaining platform 57, thereby covering the filter through-hole 58.

[0051] The filter holder 55 also has a filter holder cover 60, which is disposed on the side of the filter holder 55 opposite to the cylindrical tube 41. The filter holder cover 60 includes a cover body 61, which has a [missing information - likely a feature or design feature]. Figure 2B The first side facing upwards and in Figure 2B The second side faces downwards and is opposite to the first side. A pressing ring 62 is provided on the second side of the retainer cover body 61. The pressing ring 62 extends toward the clamping ring 59 and is configured to apply pressing force to the clamping ring 59 during use. On this first side, the filter retainer cover 60 has an outlet conduit 63 arranged to connect to a vacuum pump (not shown).

[0052] like Figure 2B As shown, the material collector 40 has a filter 70 configured to filter fluid flowing from the freeze-drying chamber 3 to a vacuum pump (not shown). As shown, the filter 70 is positioned to define a fluid path between a fluid inlet conduit 46' and an outlet conduit 63. The filter 70 includes: a filter basket 71 having a generally annular main basket portion 72 and an adjacent flange 73 configured to be arranged above a holding platform 57; a plurality of basket rods 74 extending downward from the main basket portion 72, i.e., generally parallel to the longitudinal direction of the cylindrical tube 41; and a plurality of transverse rods 75 extending between the basket rods 74. The filter 70 also includes a filter screen 76 spanning around the filter basket, wherein the filter screen 76 has a reinforcing wire 77 disposed at its top. The reinforcing wire 77 is configured to be positioned on top of the holding platform 57 and below the adjacent flange 73 such that during use, the reinforcing wire 77 is clamped between the holding platform 57 and the adjacent flange 73 to prevent the filter from being accidentally removed. The filter screen 76 is made of a screen material with a suitable screen size so as to filter the desired material in the fluid flow from the fluid inlet conduit 46' to the outlet conduit 63 and to divide the fluid path into a first path portion downstream and a second path portion upstream.

[0053] like Figure 2A As shown, the material collector 40 includes a funnel-shaped material outlet 80 located at the lower end 44 of the cylindrical tube 41. The funnel-shaped material outlet 80 has a material outlet opening 81 defined by a material outlet opening flange 82, wherein the material outlet opening 81 is configured to allow material filtered from the fluid by the filter 70 to exit the material collector 40, particularly from the second path portion of the fluid path therein.

[0054] The freeze dryer 1 has a material receiving receiver 83 configured to receive material collected by a material collector 40. The material receiving receiver 83 has a receiver body 84 defining a receiver chamber 85 for receiving material from the material collector 40. The receiver body 85 has a connecting portion 86 connected to a material outlet opening flange 82 by means of an intermediate connector 87. A heating device 88 is provided around a portion of the receiver body 84 for heating the contents of the receiver chamber 85.

[0055] like Figure 1A and Figure 2AAs shown, the freeze dryer 1 includes a purge inlet 90, wherein a purge conduit 91 is arranged at and extends into the outlet conduit 63 of the material collector 40. The purge inlet 91 has a connection valve 92 configured to connect to a purge source (not shown) to provide purge return flow to a filter 70 within the material collector 40, thereby purifying the material from the filter 70.

[0056] like Figure 1A As shown, the freeze dryer 1 also includes a connection manifold 95 with multiple connectors 96, for example, for connection to a gas conduit 97, which is connected to a gas valve 98 configured to connect to a gas source (not shown). On the side facing the freeze-drying chamber 3, the connection manifold 95 is provided with a nozzle 99 for allowing gas to enter the freeze-drying chamber 3, thereby producing gas discharged into the freeze-drying chamber 3.

[0057] During use, the material to be dried, or a mixture of materials to be dried, is introduced into the freeze-drying chamber 3. After the material or mixture is introduced, the top cover 13 is closed, and the temperature inside the freeze-drying chamber 3 is then lowered to a temperature close to or above the freezing temperature of the material or mixture by introducing a heat exchange medium into the double-jacketed container wall 10. Optionally, the material or mixture is pre-cooled or pre-frozen into granular ice particles before being introduced into the freeze-drying chamber 3, or it is pre-frozen or pre-cooled by means of cooling the material or mixture through the double-jacketed container wall 10.

[0058] Following the cooling step, the pressure within the freeze-drying chamber 3 is controlledly reduced using a vacuum pump (not shown) until it approaches a pressure suitable for sublimation / freeze-drying. The appropriate pressure depends on the product and process characteristics but may be in the range of 0.1 to 3 mbar. The reduction in pressure within the freeze-drying chamber 3 results in a corresponding decrease in the temperature within the chamber and the temperature of the material or mixture until freezing begins. During the freezing step, the movement of the stirring screw 16 ensures that the material or mixture does not freeze into solid ice clumps, as fine, loose ice particles are desired at the end of the freezing step. Alternatively, to support sublimation, the temperature of the double-jacketed container wall 10 is slowly increased until the desired maximum double-jacketed container wall 10 and / or product temperature is reached, and then maintained until drying is complete.

[0059] During the freezing step, the initial material or mixture forms fine ice particles. As sublimation proceeds and the temperature of the double-jacketed container wall 10 rises, vapor flows from the freeze-drying chamber 3 via the material collector toward a vacuum pump (not shown). When this occurs, the size of the individual ice particles decreases, resulting in the release of fine (powdered) dust remaining from the drying process. The powder is carried by the vapor flow to the material collector 40, where the dust deposits on the filter screen 76 of the filter 70. When a backflushing pulse is applied to the filter via the purification inlet 90, the deposited dust is removed from the filter screen 76 and falls toward and into the material collection receiver 83. The collected material can be further dried within the material collection receiver 83 by a heating device 88 to heat the contents of the receiver chamber 85 before discharge.

[0060] It is possible that some of the dried material or mixture may not be conveyed to the material collector 40, but instead remain in the freeze-drying chamber 3 or deposit on the inner periphery of the freeze-drying chamber 3. The remaining material can be pushed out of the freeze-drying chamber 3 toward the material collector 40. This can be achieved by briefly and intermittently introducing a gaseous exhaust, such as air or nitrogen, into the freeze-drying chamber 3 via a nozzle 99. Since a vacuum condition still exists in the freeze-drying chamber, the expansion of the gas introduced into the freeze-drying chamber 3 causes the remaining dust to be blown away, thereby increasing the likelihood of it being conveyed to the filter. The gas discharged into the freeze-drying chamber 3 can also be used to optimize process yield.

[0061] If necessary, a post-mixing step can be performed at the end of drying by collecting the material from the material collection receiver 83 and reintroducing it into the freeze-drying chamber 3. Mixing is achieved by means of the stirring screw 16, thereby recovering the individual batch at the end.

[0062] Figure 3A Another embodiment of the freeze dryer 101 according to the present invention is shown. To avoid reintroducing features of the freeze dryer 101, such as those concerning... Figure 1A , 1B The features described in 2A and 2B that have been introduced relative to the first embodiment are indicated by the same reference numerals with an increase of 100.

[0063] Figure 3A The freeze dryer 101 shown is Figure 1A The difference in the freeze dryer 1 shown is that the material collector 140 is placed on top of the conical container 102. (As shown) Figure 3BAs shown, valve 200, specifically butterfly valve 200, is arranged at the first connecting flange 132 of the outlet bus 131 at one end of valve 200. Material opening flange 182 of material collector 140 is arranged at the other end of valve 200 opposite to one end of valve 200, allowing fluid to flow from freeze-drying chamber 103 into material collector 140 via material outlet opening 181. Valve 200 is movable between a closed state and an open state, in which no fluid can pass through valve 200, and in which fluid can move from freeze-drying chamber to material collector 140 via valve 200, or vice versa.

[0064] Furthermore, the freeze dryer 101 is provided with a bypass conduit 210, which has a first conduit end 211 and a second conduit end 212 opposite to the first conduit end 211. For example... Figure 3A As shown, the bypass conduit 210 is connected at its first conduit end 211 to the fluid inlet conduit 146 of the material collector 140, specifically to the second connecting flange 149 of the material collector 140. The bypass conduit 210 is connected at its second conduit end 212 to a T-connector 214. As shown, the T-connector 214 is also provided with an observation glass 230.

[0065] Valve 200 and bypass conduit 210 are configured to allow the recirculation of fine ice particles during the sublimation phase. In the context of this patent application, it should be noted that during the freezing and early sublimation phases, the vapor flow through material collector 140 and toward a vacuum pump (not shown) is at its peak. During this phase, some fine, loose ice particles can be carried along with the vapor flow toward the filter 170 of material collector 140. Valve 200 between freeze-drying chamber 103 and material collector 140 is in its open position during the early stages of the freezing and sublimation phases, thereby allowing the fine ice particles to be recirculated back into freeze-drying chamber 103 instead of being retained in filter 70. As drying proceeds and more (powdered) dust is released from the ice matrix, valve 200 enters its closed state. After valve 200 is closed, the released dust is forced along with the vapor flow via bypass conduit 210 to the filter 170 of material collector 140. Once the dust has been filtered out of the vapor stream by filter screen 176, it falls from filter screen 176 onto the closed valve 200. During this drying stage, valve 200 acts as a dust receiver to temporarily hold the collected dust. Near the end of the drying process, valve 200 is opened to allow the dust collected on valve 200 to return to the freeze-drying chamber 103.

[0066] For example, determining when to close valve 200 can be largely based on the onset of dust release, which can be assessed by monitoring an increase in pressure drop across material collector 140, or tailored to coincide with the start of a filter backflush pulse via visual inspection of the process or any other process analysis tool. On the other hand, determining when to reopen valve 200 near the end of the freeze-drying process depends on a decrease in vapor flow, or when maximum temperatures are reached at the double-jacketed container wall 110 and / or the material or mixture, or when the pressure within the freeze-drying chamber 103 has sufficiently decreased. At the end of the drying process, individual product batches are discharged from freeze-dryer 101. Alternatively, dust within material collector 140 can be collected separately from the remaining material or mixture in freeze-drying chamber 103.

[0067] It should be understood that the above description is intended to illustrate the operation of preferred embodiments and is not intended to limit the scope of the invention. Based on the foregoing discussion, many variations will be apparent to those skilled in the art, and these variations will still be included within the scope of the invention.

Claims

1. A freeze dryer, including: A freeze-drying chamber having an inlet for allowing material to be dried to be introduced into the freeze-drying chamber and configured to be at least partially emptied; as well as A vacuum source, which is in fluid communication with the drying chamber and configured to at least partially evacuate the freeze-drying chamber, wherein a vacuum fluid path is defined between the freeze-drying chamber and the vacuum source. The freeze dryer further includes a material collector configured to collect dried material from the freeze-drying chamber. The material collector is disposed outside the freeze-drying chamber and within the vacuum fluid path between the freeze-drying chamber and the vacuum source. The material collector is positioned at a first height, and the freeze-drying chamber is positioned at a second height. The freeze dryer further includes a valve disposed within the vacuum fluid path and between the freeze-drying chamber and the material collector, wherein the valve is configured to move between an open position for allowing fluid flow from the freeze-drying chamber to the material collector, a closed position for preventing fluid flow from the freeze-drying chamber to the material collector, and / or an intermediate position for limiting fluid flow from the freeze-drying chamber to the material collector. The freeze dryer further includes a fluid bypass conduit disposed between the freeze drying chamber and the material collector, and a bypass fluid path bypassing the valve is provided between the freeze drying chamber and the material collector.

2. The freeze dryer of claim 1, wherein, The material collector is arranged next to and / or near the freeze-drying chamber.

3. The freeze dryer of claim 1 or claim 2, wherein, The material collector includes a collector housing and a collection device. The collector housing has an inlet in fluid communication with the freeze-drying chamber, a vacuum outlet in fluid communication with the vacuum source, and a collector fluid path between the inlet and the outlet. The collection device is located between the inlet and the outlet and divides the collector fluid path into a first path portion downstream of the collection device and a second path portion upstream of the collection device.

4. The freeze dryer of claim 3, wherein, The collection device includes a collection filter screen disposed between the inlet and the outlet, which divides the fluid path of the collector into a first path portion downstream of the collection filter screen and a second path portion upstream of the collection filter screen.

5. The freeze dryer according to claim 3, characterized in that, The collector housing has a material outlet in fluid communication with a first path portion or a second path portion of the collector fluid path, and the material outlet is configured to allow material collected by the collecting device to leave the collecting device.

6. The freeze dryer according to claim 3, characterized in that, The collector housing has a bottom, wherein a material outlet is arranged at or near the bottom of the collector housing.

7. The freeze dryer according to claim 3, characterized in that, The collector housing has a double-jacketed wall configured to receive heating fluid for heating fluid flowing through the collector fluid path and / or dry material collected in the material collector.

8. The freeze dryer according to claim 1, characterized in that, The freeze dryer includes a material collection receiver configured to receive material collected by the material collector and located at or near the material collector.

9. The freeze dryer according to claim 8, characterized in that, The material collection receiver has a receiver body, in which a receiver chamber is defined for receiving the collected material.

10. The freeze dryer according to claim 8, characterized in that, The material receiver is arranged at the material outlet to receive the collected material from the material collector.

11. The freeze dryer according to any one of claims 8-10, characterized in that, The material receiver is configured to heat the collected material received therein.

12. The freeze dryer according to claim 11, characterized in that, The receiver body of the material collection receiver has a double-jacketed wall configured to allow the circulation of heated fluid.

13. The freeze dryer according to claim 1, characterized in that, The material collector is located on top of the freeze-drying chamber.

14. The freeze dryer according to claim 1, characterized in that, The material collector is located above the freeze-drying chamber.

15. The freeze dryer according to claim 1, characterized in that, The valve is also configured to temporarily retain the material collected by the material collector when it is in the closed position.

16. The freeze dryer according to claim 1, characterized in that, It also includes a purification inlet in fluid communication with the vacuum fluid path and downstream of the material collector, wherein the purification inlet is configured to connect to a purification source to allow the material collector to be supplied with a purge pulse.

17. The freeze dryer according to claim 1, characterized in that, It includes a substantially conical container defining the freeze-drying chamber, and includes a stirring member disposed within the freeze-drying chamber and configured to stir material introduced into the freeze-drying chamber.

18. The freeze dryer according to claim 17, characterized in that, The substantially conical container includes a cover for sealing the top of the freeze-drying chamber, wherein the cover and / or the substantially conical container are provided with one or more nozzles having outlets oriented into the freeze-drying chamber and configured to be connected to a gas source.

19. The freeze dryer according to any one of claims 17-18, characterized in that, The generally conical container includes a releasable outlet at its bottom, which is closed by default but can be opened.

20. A material collector for use in the freeze dryer according to claim 1.

21. A method for freeze-drying or sublimating a material to be dried using a freeze dryer according to claim 1, characterized in that, The method includes the following steps: - Introducing the material to be dried into the freeze-drying chamber of the freeze dryer; and - The freeze-drying chamber is at least partially emptied using a vacuum source in order to reduce the pressure inside the freeze-drying chamber to a predetermined pressure level or below a predetermined pressure level. The method further includes the step of collecting dried material from the freeze-drying chamber by means of a material collector disposed outside the freeze-drying chamber and within the fluid path between the freeze-drying chamber and the vacuum source.

22. The method according to claim 21, characterized in that, The process includes the following steps: lowering the temperature inside the freeze-drying chamber to a temperature close to the freezing temperature of the material to be dried.

23. The method according to claim 22, characterized in that, Before emptying the freeze-drying chamber, the following steps are performed: the temperature inside the freeze-drying chamber is reduced to a temperature close to the freezing temperature of the material to be dried.

24. The method according to claim 21, claim 22 or claim 23, characterized in that, The process includes the following steps: introducing gaseous emissions into the freeze-drying chamber.

25. The method according to claim 24, characterized in that, At the end or near the end of the freeze-drying process, the following steps are performed: introducing gaseous emissions into the freeze-drying chamber.

26. The method according to claim 24, characterized in that, The gaseous emissions are intermittent.

27. The method according to claim 21, claim 22, claim 23 or claim 25, characterized in that, Includes the following steps: Backflush pulses are provided on the material collector.

28. The method according to claim 27, characterized in that, The following steps are performed periodically: a backflush pulse is provided on the material collector.

29. The method according to claim 24, characterized in that, Includes the following steps: Backflush pulses are provided on the material collector.

30. The method according to claim 29, characterized in that, The following steps are performed periodically: a backflush pulse is provided on the material collector.

31. The method according to claim 21, characterized in that, The process includes the following steps at the end of the freeze-drying process: reintroducing the material collected by the material collector into the freeze-drying chamber and post-mixing the reintroduced material with the remaining material in the freeze-drying chamber.

32. The method according to claim 21, characterized in that, The material collector is disposed at a first height, and the freeze-drying chamber is disposed at a second height, and / or wherein the material collector is located on top of the freeze-drying chamber, wherein the freeze-dryer includes a valve disposed within the vacuum fluid path and between the freeze-drying chamber and the material collector, wherein the valve is configured to move between an open position for allowing fluid flow from the freeze-drying chamber to the material collector, a closed position for preventing fluid flow from the freeze-drying chamber to the material collector, and / or an intermediate position for limiting fluid flow from the freeze-drying chamber to the material collector, and wherein the freeze-dryer includes a fluid bypass conduit disposed between the freeze-drying chamber and the material collector, and a bypass fluid path bypassing the valve is provided between the freeze-drying chamber and the material collector, wherein the method includes the following steps: The valve is kept in its open position during freezing and the early stages of sublimation, allowing tiny ice particles to recirculate back into the freeze-drying chamber; and As drying proceeds and more dust is released from the freeze-drying chamber, the valve is moved to its closed position, thereby forcing the released dust to move to the material collector via the bypass conduit.

33. The method according to claim 21, characterized in that, The material collector is disposed at a first height, and the freeze-drying chamber is disposed at a second height, and / or wherein the material collector is disposed above the freeze-drying chamber, wherein the freeze-dryer includes a valve disposed within the vacuum fluid path and between the freeze-drying chamber and the material collector, wherein the valve is configured to move between an open position for allowing fluid flow from the freeze-drying chamber to the material collector, a closed position for preventing fluid flow from the freeze-drying chamber to the material collector, and / or an intermediate position for limiting fluid flow from the freeze-drying chamber to the material collector, and wherein the freeze-dryer includes a fluid bypass conduit disposed between the freeze-drying chamber and the material collector, and a bypass fluid path bypassing the valve is provided between the freeze-drying chamber and the material collector, wherein the method includes the following steps: The valve is kept in its open position during freezing and the early stages of sublimation, allowing tiny ice particles to recirculate back into the freeze-drying chamber; and As drying proceeds and more dust is released from the freeze-drying chamber, the valve is moved to its closed position, thereby forcing the released dust to move to the material collector via the bypass conduit.

34. The method according to claim 32 or 33, characterized in that, The method further includes the following steps: At the end or near the end of the drying process, the valve is moved to its open position so that the dust collected on the valve can be returned to the freeze-drying chamber.

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