The present invention relates to an apparatus for providing a crystal line powder of a material, comprising: an evaporator for warming and concen trating a liquid solution of said material, said evaporator being adapted to be energized by an external power source; a crystallizer for cooling the concen trated liquid solution for the material to crystalize; and a dryer for drying crys tallized material, with a hot air inlet for subjecting the crystallized material to hot air to provide a dried crystalline powder.

An apparatus of the above kind is as such known in the art and is used e.g. for producing lactose powder.

In an apparatus of the above kind demands exist for cooling for the evaporator and the crystallizer and a heating demand exist e.g. for heating air for the dryer.

In relation to the dryer is should be noted that in general drying is a mass transfer process consisting of the removal of a solvent, the solvent being e.g. water and/or organic liquids as explained in the opening part of WO 2018/091049 A1 , incorporated herein by reference, and whereas the present invention is not limited to a specific solvent, water is used herein as a general example.

Further, it should be understood that whereas air is referred to herein as the medium used in the dryer for drying the crystalline material, another suitable gas than atmospheric air could be used and the term “air” as used herein is intended to include such gas.

It should also be understood that for the dryer a number of different kinds of apparatuses may be used such as e.g. spray dryers, flash dryers, ring dryers, fluidized bed dryers, belt dryers, etc.

As e.g. disclosed in the above WO 2018/091049 A1 it is known in re lation to dryers, when demands for both heating and cooling are present for the process to be executed by the apparatus, to use a heat pump for transferring energy from the processes demanding cooling to the processes demanding heating thereby overall saving energy and costs.

The process disclosed in WO 2018/091049 A1 relates to drying whereby at least a base amount of heat for heating air to be let into the dryer for subjecting a material to be dried to hot air, is provided by a heat pump. As a source of heat energy to be transferred by the heat pump a dew point dehu midification is used together with latent and/or sensible heat from exhaust gas from the dryer, whereby a varying potential of heat from the dew point dehu midification is compensated by an appropriate amount of the latent and/or sen sible heat of the exhaust gas to provide a source for meeting a substantially constant demand of energy for the heating of air to be let into the dryer.

Compared to the disclosure of WO 2018/091049 A1 the present inven tion relates to a different process.

It is an object of the present invention to provide for a reduction of energy consumption and/or costs of running and operating an apparatus for providing a crystalline powder of a material of the kind mentioned by way of introduction.

To fulfil this object an apparatus as mentioned by way of introduction further comprises: a heat pump adapted to transfer heat energy from a cold side to a hot side by means of a first circuit circulating a refrigerant, the hot side comprising a hot part and a very hot part, the heat pump comprising first heat exchangers, the first heat exchangers comprising: a cold heat exchanger at tached to the cold side; a hot heat exchanger attached to the hot part; and a very hot heat exchanger attached to the very hot part, said first heat exchang ers forming part of the first circuit and being adapted to exchange heat energy with a second circuit comprising several physically interconnected loops and being adapted to circulate a heat transfer fluid between said first heat exchang ers and peripheral heat exchangers, the peripheral heat exchangers compris ing: a crystallization heat exchanger provided in a loop connected to the cold heat exchanger and adapted to provide for cooling the concentrated liquid so lution in the crystallizer; a pre-heat heat exchanger provided in a loop con nected to the hot heat exchanger and adapted to heat air for hot air inlet of the dryer upstream of the hot air inlet; and a main-heat heat exchanger provided in a loop connected to the very hot heat exchanger and adapted to heat air for the hot air inlet of the dryer upstream of the hot air inlet, and the apparatus comprising at least one of: an additional loop of the second circuit being pro vided for connecting the hot heat exchanger or the very hot heat exchanger with an external heat sink; a condense heat exchanger provided in a loop con nected to the cold heat exchanger and adapted to exchange heat energy with evaporated solvent and/or surplus steam from the evaporator; and a connec tion, e.g. through a first external heat exchanger, to an external source to pro vide additional heating to the inlet air upstream of the hot air inlet of the dryer, and whereby the heat pump and second circuit is configured to at least fulfil the cooling needs of the crystallizer.

In the crystallizer heat exchange may e.g. be performed either via a heat exchanger (external) or directly on a jacket of crystallization tanks by cir culating the heat transfer fluid of the second circuit through said jacket(s).

Using a heat pump to provide for cooling of the crystallizer entails that the need for using ice-water in the process, as is known, may be avoided.

The second circuit will in operation be circulating a fluid heat transfer medium, i.e. a heat transfer fluid, e.g. water. Thus the fluid heat transfer me dium circulated in the second circuit will herein i.a. be referred to as water though it should be understood that any other suitable fluid medium may be used within the scope of the present invention.

Water emerging from the cold heat exchanger may have a tempera ture in a range from 0.5 - 4°C and up to 8 - 12°C, water emerging from the hot heat exchange may have a temperature in the range of 30°C to 75°C, and water emerging from the very hot heat exchanger may have a temperature in the range of 75°C to 135°C or 140°C or more, according to the potential of the heat pump. As heat pump, as an example a heat pump using CO2 as a medium and operating a cycle at least partially in supercritical condition may be used in con nection with the present invention.

The apparatus preferably comprises a control device for controlling the operation of the heat pump and the second circuit. As part of the control device the apparatus may include any such valves, pumps, sensors, etc. that the skilled person will appreciate.

Thus, in the apparatus e.g. the second circuit is typically configured to be controlled by flow, flow direction, pressure and temperature in respective parts of said second circuit to manage transfer of heat from each of the con dense heat exchanger and the crystallization heat exchanger to the heat trans fer fluid, from the heat transfer fluid to the cold (evaporation) side of the heat pump, from any hot side of the heat pump to the heat transfer fluid, and from the heat transfer fluid to each of the pre-heat heat exchanger and the main- heat heat exchanger.

In an embodiment, the dryer is a spray dryer and comprises an atom izer for atomizing a liquid solution comprising the crystalized material and the spray dryer is configured for subjecting the atomized liquid solution to the hot air to provide a dried crystalline powder. The atomizer may be any kind of at omizer known in the art, e.g. a rotary atomizer or a nozzle, e.g. a pressure nozzle or a two-fluid nozzle, etc.

In another embodiment, the dryer may be e.g. a fluid bed dryer or a flash dryer, etc.

In an embodiment, a source of steam is attached to the evaporator to provide energy for warming the liquid solution in the evaporator.

In an embodiment, a solvent heat exchanger provided in a loop con nected to the cold heat exchanger is attached to the evaporator and adapted to provide for cooling solvent removed from the liquid solution. In a known ap paratus such removed solvent is cooled using ice-water. In this embodiment of the present invention use of ice-water is further avoided.

In an embodiment, an exhaust air heat exchanger is provided in a loop connected to the cold heat exchanger and adapted to exchange heat energy with air exhausted from the dryer. Hereby is obtained a possibility of extracting additional energy from the sources of the apparatus when the apparatus in volves larger demands for energy that obtainable from the evaporator and the crystallizer.

In an embodiment, downstream of an outlet for crystalline powder from the dryer, a secondary dryer is provided. In a further embodiment a secondary hot air inlet is provided for letting in secondary hot air into the secondary dryer. To provide hot air for the secondary hot air inlet the apparatus may comprise at least one of a secondary pre-heat heat exchanger provided in a loop con nected to the hot heat exchanger and adapted to heat air for the secondary dryer upstream of the inlet; and a secondary main-heat heat exchanger pro vided in a loop connected to the very hot heat exchanger and adapted to heat air for the hot air inlet of the secondary dryer upstream of the inlet. Further a cool air inlet may be provided for letting in cool air into the secondary dryer. Still further a desiccant device may be provided upstream of the cool air inlet for desiccating the cool air to be let into the secondary dryer.

The secondary dryer may e.g. be a fluid bed dryer with a vibrating bot tom plate that provides for transportation of the crystalline powder being dried in the secondary dryer in a generally horizontal direction, preferably from a sec tion comprising the secondary hot air inlet, through a section comprising the cool air inlet, and to an outlet for the dried crystalline powder. Herby is obtained the possibility of initially drying residual moisture from the powder emerging from the first dryer by means of hot air and subsequently further drying and cooling the powder by means of cool dry air before letting out the powder prod uct.

In a further embodiment, the desiccant device is a desiccant wheel and a cool air heat exchanger is provided in a loop connected to the cold heat ex changer and adapted to exchange heat energy with air between the desiccant wheel and the cool air inlet. In yet a further embodiment a regeneration air inlet is provided for letting in regeneration air into the desiccating wheel for regen erating the same, and a regeneration air heat exchanger is provided in a loop connected to one of the hot heat exchanger and the very hot heat exchanger and adapted to heat regeneration air upstream of the regeneration air inlet. Hereby further heat sources and heat sinks provided in the apparatus are cou pled to the heat pump to provide for a reduced overall energy consumption to fulfil the heating and cooling demands or needs of the apparatus. In a further embodiment, a connection is provided, e.g. through a sec ond external heat exchanger, to an external source to provide additional heat ing to the regeneration air upstream of the inlet of the desiccant wheel. Hereby, e.g. the temperature of the regeneration air may be raised to a higher level than provided for by the heat pump.

In the following the invention will be further explained by way of a non limiting example of an embodiment having reference to the accompanying drawing, the only figure of which shows a diagram of an apparatus according to the invention and including a number of optional features.

In the drawing an apparatus for providing a crystalline powder of a material, comprises: an evaporator 10 for warming and concentrating a liquid solution of said material, said evaporator being adapted to be energized by an external power source, such as a source of steam 11 ; a crystallizer 20 for cool ing the concentrated liquid solution for the material to crystalize; and a dryer 30 for drying crystallized material, with a hot air inlet 31 for subjecting the crystal lized material to hot air to provide a dried crystalline powder. As such an appa ratus comprising these features is known in the art.

In the embodiment shown, the evaporator 10 receives in operation a liquid solution of the material to be crystallizes. From the evaporator 10 liquid solvent removed from the liquid solution is let out at an outlet 12 as a hot or warm liquid of e.g. 20-25°C. In a known process, depending on the further use or disposal of the warm liquid, this warm liquid may be cooled to e.g. 8-12°C using ice-water. The external power source or source of energy for the evapo rator 10 may be electric and the heating of the liquid solution in the evaporator 10 may be obtained e.g. by the technic known in the art as Mechanical Vapour Recompression.

In accordance with the present invention the apparatus further com prises: a heat pump 40 adapted to transfer heat energy from a cold side to a hot side by means of a first circuit circulating a refrigerant, the hot side com prising a hot part and a very hot part, the heat pump comprising first heat ex changers. The first heat exchangers comprise: a cold heat exchanger 41 at tached to the cold side; a hot heat exchanger 42 attached to the hot part; and a very hot heat exchanger 43 attached to the very hot part, said first heat ex changers 41 , 42, 43 forming part of the first circuit. The first heat exchangers 41 , 42, 43 are adapted to exchange heat energy with a second circuit 50 com prising several physically interconnected loops and being adapted to circulate a heat transfer fluid between said first heat exchangers and peripheral heat exchangers.

In the embodiment shown, the peripheral heat exchangers comprise: a condense heat exchanger 55 provided in a loop connected to the cold heat exchanger 41 and adapted to exchange heat energy with evaporated solvent, e.g. water, from the evaporator 10 and possible surplus steam from the ener gizing, whether the energizing is obtained by steam through the source of steam 11 or by Mechanical Vapour Recompression; a solvent heat exchanger 51 provided in a loop connected to the cold heat exchanger 41 and adapted to exchange heat energy with the hot or warm liquid solvent, e.g. water, from the evaporator’s 10 outlet 12; a crystallization heat exchanger 52 provided in a loop connected to the cold heat exchanger 41 and adapted to provide for cooling the concentrated liquid solution in the crystallizer 20; a pre-heat heat exchanger 53 provided in a loop connected to the hot heat exchanger 42 and adapted to heat air for the hot air inlet 31 of the dryer 30 upstream of the hot air inlet 31 ; and a main-heat heat exchanger 54 provided in a loop connected to the very hot heat exchanger 43 and adapted to heat air for the hot air inlet 31 of the dryer 30 upstream of the hot air inlet 31 and downstream of the pre-heat heat exchanger 53.

It should be noted that the solvent heat exchanger 51 is optional since cooling of the outlet liquid solvent may not be needed. In a known process cooling of the outlet liquid solvent is performed by means of ice-water. Thus, using in accordance with the present invention the solvent heat exchanger 51 a need for ice-water in the process may be avoided.

In the embodiment shown, the apparatus also comprises an additional loop of the second circuit 50 that is provided for connecting the hot heat ex changer 42 or the very hot heat exchanger 43 with an external heat sink 60. The external heat sink 60 may e.g. be a hot water reservoir in a facility providing for cleaning-in-place of the apparatus and/or other apparatuses nearby, that are adapted for cleaning-in-place. It is noted that cleaning-in-place, commonly known as CIP, is as such a well-known technology.

Further, in the embodiment shown, the apparatus comprises a con nection, e.g. through a first external heat exchanger 71 , to an external source 70 to provide additional heating to the inlet air upstream of the hot air inlet 31 of the dryer 30. This may provide for heating, if needed, the air for the hot air inlet 31 to a temperature level not obtainable by means of the heat pump 40.

In the apparatus according to the invention, the heat pump 40 and second circuit 50 together may be configured to at least fulfil the cooling needs of the crystallizer 20 and possibly also of the evaporator 10.

As indicated in the drawing, the embodiment shown comprise a control device 80 for controlling the operation of the heat pump 40 and the second circuit 50.

Though not shown in any detail, in the present embodiment the second circuit is configured to be controlled by flow, flow direction, pressure and tem perature in respective parts of said second circuit to manage transfer of heat from each of the condense heat exchanger and the crystallization heat ex changer to the heat transfer fluid, from the heat transfer fluid to the cold (evap oration) side of the heat pump, from any hot side of the heat pump to the heat transfer fluid, and from the heat transfer fluid to each of the pre-heat heat ex changer and the main-heat heat exchanger.

In the embodiment shown, an exhaust air heat exchanger 56 is pro vided in a loop connected to the cold heat exchanger 41 and adapted to ex change heat energy with air exhausted from the dryer 30.

Further, in the embodiment shown, downstream of an outlet for crys talline powder from the dryer 30, a secondary dryer 32 is provided. A secondary hot air inlet 33 may as shown be provided for letting in secondary hot air into the secondary dryer 32. As shown a secondary pre-heat heat exchanger 57 provided in a loop connected to the hot heat exchanger and adapted to heat air for the secondary dryer upstream of the inlet 33 and a secondary main-heat heat exchanger 58 provided in a loop connected to the very hot heat exchanger and adapted to heat air for the hot air inlet of the secondary dryer 32 upstream of the inlet 33 may be provided or only one of these two heat exchangers 57. 58 may be provided.

As further shown, a cool air inlet 34 may be provided for letting in cool air into the secondary dryer 32. A desiccant device 90 may be provided up stream of the cool air inlet 34 for desiccating the cool air to be let into the sec ondary dryer 32. The desiccant device may be a desiccant wheel 90 and a cool air heat exchanger 59 may be provided in a loop connected to the cold heat exchanger and adapted to exchange heat energy with air between the desic cant wheel 90 and the cool air inlet 34.

When a desiccant wheel 90 is used provisions are made for regener ating the desiccant wheel and thus, in the embodiment shown, a regeneration air inlet 91 is provided for letting in regeneration air into the desiccating wheel for regenerating the same, and a regeneration air heat exchanger 92 is pro vided in a loop which in the present embodiment is connected to the hot heat exchanger 42 and adapted to heat regeneration air upstream of the regenera tion air inlet 91 .

Further, in the embodiment shown a connection is provided, e.g. as shown through a second external heat exchanger 93, to an external source 94 to provide additional heating to the regeneration air upstream of the inlet 91 of the desiccant wheel 90.

The apparatus described above may e.g. be used for producing lac tose powder (or a crystallized whey powder or derivative, such as whey per meate powder). Thereby a solution of lactose is initially fed into the evaporator 10 to be concentrated therein. The evaporator 10 uses steam and/or electricity as energy (source 11 ) to remove water from the lactose. Residual steam from the energization, whether by a source of steam 11 or e.g. by mechanical vapour recompression, needs to be condensed which takes place in the condense heat exchanger 55, whereby a low pressure is maintained in the evaporator 10 to promote the evaporation of water and thus of concentration of the lactose.

As a co-product a hot or warm stream of condensate is created from the water removed. This stream is cooled in the solvent heat exchanger 51 .

After the evaporation step, lactose is transferred to the crystallizer 20 to be cooled down for several hours in order to create lactose crystals. The crystallizer 20 may comprise several separate tanks. The cooling is provided for by cold water from the cold heat exchanger 41 of the heat pump through the crystallization heat exchanger 52.

Lactose crystals are subsequently sent to the dryer 30 where they are dried into lactose powder by removing the water part in it. If a spray dryer is used as the dryer 30, lactose crystals are sprayed into a hot and dry air stream in the dryer 30. The air stream in the dryer may need to be hotter than the temperature provided for by the very hot heat exchanger 43 and thus the wanted or needed temperature may be obtained through external source 70 and the first external heat exchanger 71 . If e.g. a fluid bed dryer or a flash dryer is used the temperature of the hot and dry air provided by the very hot heat exchanger 43 may suffice. It is possible to include in an apparatus according to the invention a step of mechanical separation of the crystals produced in the crystallizer 20 before the drying step. Such mechanical separation may e.g. be used before drying by means of a fluid bed dryer or a flash dryer. Post drying air streams may be provided e.g. in the secondary dryer 32 through the sec ondary hot air inlet 33 and the cool air inlet 34 to provide the final product in a dry and cool condition as may be needed by the circumstances.

Apart from lactose e.g. whey powder, demineralized whey powder or whey permeate powder may be produced using an apparatus according to the present invention.