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    • 专利摘要:
    A cooling system for supplying, and a method of supplying, cooled intake air to a fluid bed dryer (20) for use as cooled intake air in cooling a warm or hot material in said fluid bed dryer (20); said method comprising in a cooling system according to the invention, supplying primary air along a primary air flow path (41) to a dry side of an indirect evaporative cooler (40), and secondary air along a secondary air flow path (42a,42b) to a wet side of said same indirect evaporative cooler (40); permitting said primary air to traverse said dry side of said indirect evaporative cooler (40), thereby becoming cooled intake air, and permitting said secondary air to traverse said wet side of said indirect evaporative cooler (40), thereby becoming cooled and moist secondary air; and supplying said cooled intake air to said fluid bed dryer (20) via a fluid bed dryer intake air flow path (21) connecting said dry side of said indirect evaporative cooler (40) to said fluid bed dryer(20)
    公开号:DK201500373A1
    申请号:DKP201500373
    申请日:2015-07-01
    公开日:2017-01-16
    发明作者:Thomas Rønnow Olesen；Rasmus Toftegaard
    申请人:Cotes As；
    IPC主号:
    专利说明:

    TITLE A cooling system and a method of cooling dry intake air to drying systems.
    FIELD
    In the field of drying systems and fluid bed drying there is suggested a cooling system with improved energy efficiency for providing cold and dry intake air to a drying system e.g. a fluid bed dryer and a method of cooling and drying intake air to a drying system e.g. a fluid bed dryer.
    BACKGROUND
    In the industrial production of powders such as e.g. milk powders, cheese powders, or pharmaceutical powders it is routinely a part of the production line that a starting material is in a first step spray dried in a spray dryer to the generate the powderous material or powder which is followed in a second step by fluid bed drying wherein the powderous material or powder is cooled and further dried. This two-step process is often necessary due to the high exit temperature of the powder from the spray dryer, which renders the generated powders highly hygroscopic during cool-down to ambient temperatures.
    In the fluid bed dryer, drying is typically a multi-step process characterized by supplying dry intake air to the fluid bed dryer wherein the dry intake air is being reduced in temperature from a starting temperature which is comparable to the exit temperature of the powder from the spray dryer to, or comparable to, ambient temperature in a series of consecutive steps, often two, by lowering the temperature of the dry intake air between steps. A conventional process of the art is described in WO 95/ 14644.
    In the art it is customary to manufacture cooled and dry intake air for the fluid bed drying process by passing ambient air through a condensation dryer, typically comprising an ice-water unit. Here the air is cooled to below the dew-point where, in response, the air exudes water and the absolute humidity [g/kg] is reduced. However, because the temperature drops concomitantly the relative humidity increases towards 100%. This constitutes a significant problem for the subsequent drying. To compensate for this drawback the drying air is subsequently heated.
    Conventional drying air systems in the art have several drawbacks some of which are listed here. They are unnecessary energy demanding, as energy is required both for cooling and for subsequent heating, and they pose a significant hygiene problem as both the condensation water and the resulting high humidity pose a significant risk for bacterial growth in the condensation cooler, whereby bacterial growth is subsequently at risk of being transported by the air-flow into the powder product. This can partially be compensated for by the heating being carried out in a adsorption de-moisturizer, which at the same time heats the intake air and reduces bacterial inflow, however the system remains unnecessary energy demanding.
    It is the aim of the present invention to solve at least some of the above problems of drying air systems for fluid bed dryers. To this purpose the present inventors suggest the use of indirect evaporative cooling for drying and cooling intake air for fluid bed dryers as detailed in the claims and description of the present disclosure . US 6,018,953 describes a method of conditioning a process stream of air in an air conditioning system wherein a process stream of air is dehumidified and cooled to provide a conditioned stream of air for introduction to a conditioned space. The method comprises the steps of providing an adsorption wheel having a multiplicity of passages through which process air can flow for adsorbing moisture therefrom, the wheel capable of adsorption of moisture from the process air and of regeneration on a continuous basis as the wheel rotates. An indirect evaporative cooler is provided having a dry side and a wet side separated by a moisture-impervious wall wherein heat is extracted from said dry side through the wall to the wet side. Cooling in the dry side is achieved by evaporation of water into air passing through the wet side. The process air is passed through the adsorption wheel to remove moisture therefrom to provide a moisture-depleted stream of process air exiting the adsorption wheel. The adsorption wheel is regenerated by passing hot gases therethrough to remove moisture from the adsorption wheel. The moisture-depleted stream of process air exiting said adsorption wheel is divided into a relatively hot stream and a relatively cool stream, and the relatively hot stream of process air is introduced into the wet side of the indirect evaporative cooler, and the relatively cool stream is introduced into the dry side, the relatively hot stream evaporating water thereinto thereby cooling the moisture-impervious wall and removing heat from the relatively cool stream to provide cooled air to be introduced to a conditioned space. WO 2005/106343 details the construction of an enthalpy exchanger (an indirect evaporative cooler in the parlance of the present invention), which reference is incorporated into the present disclosure in its entirety. The indirect evaporative cooler of WO 2005/106343 is manufactured and sold by Statigcooling B.V. of Holland and is considered particularly suitable for use in the systems and units of the present invention.
    In the present invention, we describe a flexible, inexpensive, and simple system that is capable of delivering a dry and cold airstream for ventilating a drying process in a fluid bed dryer. In operation the system creates dry air, thereby eliminating condensation in the ventilation system; and furthermore the outlet and inlet airstreams are separated which minimize the risks of contaminating the inlet air stream.
    SUMMARY OF THE INVENTION
    The present invention is detailed in the description, the claims and in the drawings. In particular there is disclosed:
    In a first embodiment a cooling system (1,2,3,4,5,6,7) for supplying cooled intake air to a fluid bed dryer (20) for use as cooled intake air in cooling a warm or hot material to be dried in said fluid bed dryer (20); said cooling system (1,2,3,4,5,6,7) comprising: an indirect evaporative cooler (40) comprising a dry side and a wet side; a primary air flow path (41) connecting to said dry side upstream from said indirect evaporative cooler (40); a secondary air flow path (42a, 42b) connecting to said wet side upstream and downstream of said indirect evaporative cooler (40), a fluid bed dryer intake air flow path (21) connecting to said dry side downstream from said indirect evaporative cooler (40); said cooling system (1,2,3,4,5,6,7) arranged to permit a flow of intake air for said fluid bed dryer to reach said dry side of said indirect evaporative cooler (40) as primary air along said primary air flow path (41); and arranged to permit a flow of secondary air to reach said wet side of said same indirect evaporative cooler (40) along said secondary air flow path (42a); permitting said primary air to traverse said dry side of said indirect evaporative cooler (40), thereby becoming cooled intake air; and permitting said secondary air to traverse said wet side of said indirect evaporative cooler (40), thereby becoming cooled and moist secondary air; and supplying said cooled intake air to said fluid bed dryer (20) via said fluid bed dryer intake air flow path (21) connecting said dry side of said indirect evaporative cooler (40) to said fluid bed dryer (20) ; said cooling system (1,2,3,4,5,6,7) further comprising air moving units for moving air along said air flow paths (21,41,42a,42b).
    In a second embodiment a cooling system (1,2,3,4,5,6,7) according to said first embodiment further comprising a bypass air flow path (43) for directing and mixing a flow of primary air to said cooled intake air exiting said indirect evaporative cooler (40) at a first temperature to obtain cooled intake air of a second temperature, said second temperature higher than said first temperature.
    In a third embodiment a cooling system (1,2,3,4,5,6,7) according to either said first or second embodiments further comprising a redirection air flow path (44) for redirecting and/or mixing a flow of cooled primary air to said secondary air upstream from said indirect evaporative cooler (40) along said secondary air flow path (42a).
    In a fourth embodiment a cooling system (2,3,5,6,7) according to any of the first to third embodiments further comprising a primary air dehumidifier (50), preferably a desiccant dehumidifier, and most preferably a rotary desiccant wheel, arranged on said primary air flow path (41a,41b) upstream from said indirect evaporative cooler (40).
    In a fifth embodiment a cooling system (2,3,5,6,7) according to the fourth embodiment wherein said primary air dehumidifier is a rotary desiccant wheel (50) arranged on said primary air flow path (41a,41b) upstream from said indirect evaporative cooler (40), said rotary desiccant wheel (50) comprising a process section (51) and a regeneration section (52), said primary air flow path (41a,41b) traversing said rotary desiccant wheel (50) by said process section (51); said cooling system further comprising at least one regeneration air heating unit (54) for heating intake air to obtain heated regeneration air, which can be led to said regeneration section (52) of said rotary desiccant wheel (50), along a regeneration air flow path (53) , and at least one air moving unit for moving intake air and heated regeneration air along said regeneration air flow path (53).
    In a sixth embodiment a cooling system (2,3,5,6,7) according to the fifth embodiment wherein said at least one regeneration air heating unit (54) has been replaced, at least partially, by heat exchangers (54a,54b,54c) for recovery of heat stored in release air.
    In a seventh embodiment a cooling system (2,3,5,6,7) according to either the fifth of the sixth embodiments wherein said at least one regeneration air heating unit (54) is replaced by at least one regeneration air heat exchanger (54) located on one or more exhaust air flow paths (12,22) for release air from a spray dryer (10) and/or said fluid bed dryer (20).
    In an eighth embodiment a cooling system (2,3,5,6,7) according to either the fifth of the sixth embodiments wherein said at least one regeneration air heating unit (54) is partially replaced by a primary air heat exchanger (54a) located downstream from said rotary desiccant wheel (50) on a second stretch (41b) of said primary air flow path (41) augmented by a supplementary regeneration air heating unit located on said regeneration air flow path (53) between said heat exchanger (54a) and said rotary desiccant wheel (50).
    In a ninth embodiment a cooling system (1,2,3,4,5,6,7) according to any of the previous embodiments wherein the secondary air is dehumidified prior to traversing said wet side of said indirect evaporative dryer (40).
    In an tenth embodiment a cooling system (1,2,3,4,5,6,7) according to any of the previous embodiments further comprising a secondary air dehumidifier (60), preferably a desiccant dehumidifier, and most preferably a rotary desiccant wheel, arranged on said secondary air flow path (42a) upstream from said indirect evaporative cooler (40) .
    In an eleventh embodiment a cooling system (6,7) according to the tenth embodiment wherein said secondary air dehumidifier is a rotary desiccant wheel (60) arranged on said secondary air flow path (42a) upstream from said indirect evaporative cooler (40), said rotary desiccant wheel (60) comprising a process section (61) and a regeneration section (62), said secondary air flow path (42a) traversing said rotary desiccant wheel (60) by said process section (61); said cooling system further comprising at least one secondary air heating unit (64) for heating intake air to obtain heated regeneration air, which can be led to said regeneration section (62) of said rotary desiccant wheel (60), along a regeneration air flow path (63), and at least one air moving unit for moving intake air and heated regeneration air along said regeneration air flow path (63).
    In an twelfth embodiment a cooling system (4,5,6,7) according to the eleventh embodiment wherein said at least one secondary air heating unit (64) has been replaced, at least partially, by heat exchangers (54a,54b,54c) for recovery of heat stored in release air.
    In a thirteenth embodiment a cooling system (4,5,6,7) according to either the eleventh or the twelfth embodiments wherein said at least one secondary air heating unit (64) is replaced by at least one secondary air heat exchanger (64) located on one or more exhaust air flow paths (12,22) for release air from a spray dryer (10) and/or said fluid bed dryer (20).
    In a fourteenth embodiment a cooling system (4,5,6,7) according to either the eleventh to thirteenth embodiments wherein said secondary air heat exchanger (64) and said primary air heat exchanger (54a) is one unit in which said primary (41b) and secondary (42a) air flow paths are crossing and heat exchanging, such that primary air is cooled while regeneration air is heated thereby augmenting the cooling capacity of said indirect evaporative heater (40).
    In a fifteenth embodiment a cooling system (2,3,4,5,6,7) according to any of the fourth to fourteenth embodiments wherein said at least one regeneration air heating unit (54) and said at least one secondary air heating unit (64) forms a combined regeneration air and secondary air heating unit, and wherein said air flow paths for regeneration air (53,63) and/or said secondary air flow path (42) are split from each other only after passage of said combined regeneration air and secondary air heating unit.
    In a sixteenth embodiment a cooling system (2,3,4,5,6,7) according to any of the fourth to fifteenth embodiments further comprising only one desiccant dehumidifier, said desiccant dehumidifier having sufficient capacity to produce dry air to supply both the needs for primary air and for secondary air, and wherein said primary (41) and said secondary (42) air flow paths are split from each other only after passage of said only one desiccant dehumidifier .
    In a seventeenth embodiment a cooling system (2,3,4,5,6,7) according to the sixteenth embodiment wherein said only one desiccant dehumidifier is a rotary desiccant wheel supplying dry air for said spray dryer (10) along a spray dryer drying air flow path (11) and wherein said primary (41) and said secondary (42) air flow paths are in fluid connection with said spray dryer drying air flow path (11).
    In an eighteenth embodiment a cooling system (1.2.3.4.5.6.7) according to any of the first to seventeenth embodiments wherein said material to be dried is a powderous material.
    In a nineteenth embodiment a fluid bed dryer (20) comprising a cooling system (1,2,3,4,5,6,7) according to any of the first to eighteenth embodiments.
    In a twentieth embodiment an arrangement comprising a spray dryer (10) and a fluid bed dryer (20) seguentially arranged to allow transport of a powderous material from said spray dryer (10) to said fluid bed dryer (20), said fluid bed dryer (20) comprising a cooling system (1.2.3.4.5.6.7) according to any of the first to eighteenth embodiments.
    In a twenty-first embodiment a method of supplying cooled intake air to a fluid bed dryer (20) for use as cooled intake air in cooling a warm or hot material to be dried in said fluid bed dryer (20); said method comprising in a cooling system according to any of the first to eighteenth embodiments, supplying primary air along a primary air flow path (41) to a dry side of an indirect evaporative cooler (40), and secondary air along a secondary air flow path (42a, 42b) to a wet side of said same indirect evaporative cooler (40); permitting said primary air to traverse said dry side of said indirect evaporative cooler (40), thereby becoming cooled intake air, and permitting said secondary air to traverse said wet side of said indirect evaporative cooler (40), thereby becoming cooled and moist secondary air; and supplying said cooled intake air to said fluid bed dryer (20) via a fluid bed dryer intake air flow path (21) connecting said dry side of said indirect evaporative cooler (40) to said fluid bed dryer (20).
    BRIEF DESCRIPTION OF THE DRAWINGS
    Figure 1: Basic cooling system and arrangement according to the invention.
    Figure 2: Basic cooling system and arrangement according to the invention further comprising a desiccant dehumidifier.
    Figure 3: Basic cooling system and arrangement according to the invention further comprising heat exchangers for heating regeneration air.
    Figure 4: Basic cooling system and arrangement according to the invention comprising a secondary air drying unit.
    Figure 5: Basic cooling system and arrangement according to the invention comprising a secondary air heating unit.
    Figure 6: Basic cooling system and arrangement according to the invention comprising a secondary air desiccant dehumidifier.
    Figure 7: Basic cooling system and arrangement according to the invention comprising a distant desiccant dehumidifier.
    DETAILED DESCRIPTION
    The basic cooling unit (40) and cooling system (1) according to the invention is disclosed in Figure 1. This basic cooling unit and cooling system forms the starting point for the further disclosed embodiments of the present invention.
    With the present invention, and as detailed in the figures, there is disclosed a cooling system (1,2,3,4,5,6,7) for supplying cooled intake air to a fluid bed dryer (20) for use as cooled intake air in cooling a warm or hot material to be dried in said fluid bed dryer (20); said cooling system (1,2,3,4,5,6,7) comprising: an indirect evaporative cooler (40) comprising a dry side and a wet side; a primary air flow path (41) connecting to said dry side upstream from said indirect evaporative cooler (40); a secondary air flow path (42a, 42b) connecting to said wet side upstream and downstream of said indirect evaporative cooler (40); a fluid bed dryer intake air flow path (21) connecting to said dry side downstream from said indirect evaporative cooler (40); said cooling system (1,2,3,4,5,6,7) arranged to permit a flow of intake air for said fluid bed dryer to reach said dry side of said indirect evaporative cooler (40) as primary air along said primary air flow path (41); and arranged to permit a flow of secondary air to reach said wet side of said same indirect evaporative cooler (40) along said secondary air flow path (42a) ; permitting said primary air to traverse said dry side of said indirect evaporative cooler (40), thereby becoming cooled intake air; and permitting said secondary air to traverse said wet side of said indirect evaporative cooler (40), thereby becoming cooled and moist secondary air; and supplying said cooled intake air to said fluid bed dryer (20) via said fluid bed dryer intake air flow path (21) connecting said dry side of said indirect evaporative cooler (40) to said fluid bed dryer (20); said cooling system (1,2,3,4,5,6,7) further comprising air moving units for moving air along said air flow paths (21,41,42a,42b).
    In a preferred embodiment the material to be dried is a powderous material. As the method and cooling unit of the invention has a very low risk of bacterial infestation it is particularly preferred that the powderous material shall be a powderous material in hazard of being infected by bacteria, in particular and even more preferred that the powderous material shall be milk powder, cream powder, cheese powder or pharmaceutical powders, such as e.g. powders for inhalation or powders for tableting.
    In a further embodiment of the present invention there is disclosed a method of supplying cooled intake air to a fluid bed dryer (20) for use as cooled intake air in cooling a warm or hot material in said fluid bed dryer (20) ; said method comprising in a cooling system according to any of the embodiments detailed herein, supplying primary air along a primary air flow path (41) to a dry side of an indirect evaporative cooler (40), and secondary air along a secondary air flow path (42a,42b) to a wet side of said same indirect evaporative cooler (40) ; permitting said primary air to traverse said dry side of said indirect evaporative cooler (40), thereby becoming cooled intake air, and permitting said secondary air to traverse said wet side of said indirect evaporative cooler (40), thereby becoming cooled and moist secondary air; and supplying said cooled intake air to said fluid bed dryer (20) via a fluid bed dryer intake air flow path (21) connecting said dry side of said indirect evaporative cooler (40) to said fluid bed dryer (20) .
    Further there is disclosed a use of an indirect evaporative cooler (40) in a method of supplying cooled intake air to a fluid bed dryer (20) for use as cooled intake air in cooling a warm or hot material in said fluid bed dryer (20); said method comprising supplying primary air along a primary air flow path (41) to a dry side of an indirect evaporative cooler (40), and secondary air along a secondary air flow path (42a,42b) to a wet side of said same indirect evaporative cooler (40) ; permitting said primary air to traverse said dry side of said indirect evaporative cooler (40), thereby becoming cooled intake air, and permitting said secondary air to traverse said wet side of said indirect evaporative cooler (40), thereby becoming cooled and moist secondary air; and supplying said cooled intake air to said fluid bed dryer (20) via a fluid bed dryer intake air flow path (21) connecting said dry side of said indirect evaporative cooler (40) to said fluid bed dryer (20) .
    In Figure 1, a generalized layout of a process plant for producing a powderous material is detailed. The powderous material is generated in a spray dryer (10) as a hot and most often also moist powderous material whereupon it is transported (along the thick black line) to a fluid bed dryer (20). In the fluid bed dryer, the powderous material is further dried and cooled to ambient temperature upon which it is transported (along the thick black line) to a powder collection unit (30) (not detailed) as a dried and cooled powderous material for further use or processing. Not detailed in the drawing are the necessary means for transporting a powderous material between the various process units. In general, this is considered outside the scope of the present invention .
    The spray dryer (10) can be any type of spray dryer known to the skilled person and the current invention is not limited by this choice. From the spray dryer (10) a spray dryer exhaust air flow path (12) is indicated from where hot and humid exhaust air leaves the spray dryer (10) after partaking in a spray drying procedure. Normally this air is released to the surroundings as release air.
    Likewise, the fluid bed dryer (20) can be any type of fluid bed dryer known to the skilled person and the current invention is not limited by this choice. From the fluid bed dryer (20) a fluid bed dryer exhaust air flow path (22) is indicated from where hot and humid exhaust air leaves the fluid bed dryer (20) after partaking in a cooling and drying fluid bed drying procedure. Normally this air is released to the surroundings as release air.
    Intake air for cooling and drying in the cooling and drying fluid bed dryer procedure is supplied to the fluid bed dryer (20) via a fluid bed dryer intake air flow path (21) connecting an indirect evaporative cooler (40) to the fluid bed dryer (20) . The indirect evaporative cooler (40) together with the above and below detailed air flow paths (21,41,41a,41b,42a,42b, 43, 44) form a cooling system (1,2,3,4,5,6,7) .
    Further comprised in the cooling system (1,2,3,4,5,6,7) of the invention are a plurality of air moving units for moving air along the air flow paths (21,41,41a,41b,42a,42b,43,44) comprised in the cooling system. Fans are most suitable for use with the present invention as air moving units, however, bellows and pumps may serve the intended purpose as well. Other air moving units as are known to the skilled person are contemplated for inclusion into the invention as well. The skilled person will know how to apply such air moving units according to the design requirements of the system.
    Indirect evaporative coolers have a cooling section, often called a "dry" section or "dry side", and an evaporation section, often called a "wet" section or a "wet side". By providing a dry side and a wet side separated by a moisture-impervious wall, heat can be extracted from (primary) air traversing the indirect evaporative cooler by the dry side through the wall to (secondary) air traversing the indirect evaporative cooler by the wet side. Water is required for the operation of indirect evaporative coolers. In the drawings and in the claims conduits and means for supplying water to the indirect evaporative coolers forming part of the invention have not been indicated or included. The skilled person will know how to supply water to an indirect evaporative cooler for its correct operation.
    When in operation, (primary) air traversing the indirect evaporative cooler by the cooling section, the dry side, will cool through heat exchange with the indirect evaporative cooler without absorbing moisture, while (secondary) air traversing the indirect evaporative cooler by the evaporation section, wet side, will absorb water, thereby cooling the indirect evaporative cooler, itself becoming moisture laden and cooler.
    Throughout the text there is made use of the expressions upstream and downstream relative to the indirect evaporative cooler included in the cooling systems of the invention. Upstream and downstream are used in their conventional meaning, such that air approaching the indirect evaporative cooler is on a flow path upstream of the indirect evaporative cooler, while air moving away from the indirect evaporative cooler is on a flow path downstream from the indirect evaporative cooler.
    Numerous indirect evaporation coolers are known in the art and are considered suitable for use with the present invention. However, it is particularly preferred that the indirect evaporation cooler used with the present invention is a counter-flow indirect evaporation cooler as detailed in the drawings of the present disclosure.
    One example of a counter-flow indirect evaporation cooler is the "wet bulb cooler". In the wet bulb cooler the secondary air flow as it traverses the wet bulb cooler is continuously cooled to 100% relative humidity and reheated by absorbing heat due to heat exchange with the primary air, whereupon it can absorb more water, cool further, become reheated, and absorb more water etc. This thermodynamic cycle will approach the wet bulb temperature of the secondary air, hence the name.
    Another example of a counter-flow indirect evaporation cooler is the dew-point cooler. In dew-point coolers, a fraction of the primary air, typically between 25-40%, is diverted from the primary air flow to be used as secondary air. Such systems are self-suppliant in secondary air and further allows for a lower resulting temperature of the primary air exiting the indirect evaporative cooler as the primary air is cooled towards the dew-point of the primary air, rather than the wet bulb temperature.
    Accordingly, the wet-bulb cooler and the dew-point cooler are considered particularly preferred in the present invention .
    In Figure 1, a primary air flow path (41) is indicated. Primary air is supplied to the indirect evaporative cooler (40) along a primary air flow path (41), and traverses the indirect evaporative cooler (40) by the cooling section, the dry side, whereupon it is cooled, becoming cooled intake air, and is directed to the fluid bed dryer (20) along the fluid bed dryer intake air flow path (21) after having traversed the indirect evaporative cooler. Secondary air is supplied to the evaporation section, the wet side, of the indirect evaporative cooler (40) along a secondary air flow path (42a,42b).
    Also disclosed with the present invention is a fluid bed dryer (20) comprising a cooling system (1,2,3,4,5,6,7) of the present invention and as detailed in the present disclosure, as well as an arrangement comprising a spray dryer (10) and a fluid bed dryer (20) sequentially arranged to allow transport of a powderous material from said spray dryer (10) to said fluid bed dryer (20), said fluid bed dryer (20) comprising a cooling system (1,2,3,4,5,6,7) of the present invention and as detailed herein. A bypass air flow path (43) is indicated in Figure 1. By supplying a bypass air flow path, primary air can be mixed to the cooled intake air for the fluid bed dryer transported along the fluid bed dryer intake air flow path (21), allowing the temperature of the intake air to be controlled between 0 and 100% of the primary air temperature prior to entering the indirect evaporative cooler, with 100% matching the temperature of the original primary air, and 0% being the temperature of the cooled intake air upon exiting the indirect evaporative cooler without any mixing in of bypassed primary air.
    In an exemplary embodiment, the bypass air flow path (43) connects to the fluid bed dryer intake air flow path (21) via an air regulation valve, preferably an air regulation valve for automated gas delivery. In general, and throughout the present disclosure, whenever air flow paths connect, the use of air regulation valves, preferably air regulation valves for automated gas delivery, is ubiquitously contemplated and applied. Accordingly, the present invention is not limited by the manner in which air flow paths connect, rather it is considered within the skills of the person in the art how to combine and divide airflows whether by passive or active regulation.
    Accordingly, there is disclosed in an embodiment of the invention a method of supplying cooled intake air to a fluid bed dryer (20)/ wherein said cooled intake air exiting said indirect evaporative cooler (40) at a first temperature is mixed with a fraction of primary air to obtain cooled intake air of a second temperature, said second temperature higher than said first temperature.
    Also disclosed is a cooling system (1) as detailed above further comprising a bypass air flow path (43) for directing and mixing a flow of primary air to said cooled intake air exiting the indirect evaporative cooler (40) at a first temperature to obtain cooled intake air of a second temperature, said second temperature higher than said first temperature.
    In Figure 1 there is further indicated a redirection air flow path (44). This redirection air flow path can redirect a fraction of cooled intake air exiting said indirect evaporative cooler (40) to said secondary air flow path (42a) prior to, i.e. upstream to, entering said indirect evaporative cooler. Thereby the evaporative capacity of the secondary air can be augmented. When the indirect evaporative cooler (40) is a dew-point cooler, the redirection air flow path (44) is the secondary air flow path (42a) and no further secondary air is supplied beyond the flow redirected along the redirection air flow path (44) from the cooled intake air exiting said indirect evaporative cooler (40).
    Accordingly there is further disclosed a cooling system (1) as detailed above further comprising a redirection air flow path (44) for redirecting and/or mixing a flow of cooled primary air to said secondary air upstream from said indirect evaporative cooler (40) along said secondary air flow path (42a).
    It is further contemplated that the cooling system (1) shall comprise a primary air dehumidifier, preferably a desiccant dehumidifier, and most preferably a rotary desiccant wheel dehumidifier, arranged on the primary air flow path (41) upstream from the indirect evaporative cooler (40). A cooling system (2) according to the invention comprising a primary air dehumidifier is detailed in Figure 2 using the most preferred embodiment, the rotary desiccant wheel, as an exemplary embodiment.
    By introducing a dehumidifier into the primary air flow path prior to cooling, it can be assured that the cooled intake air entering said fluid bed dryer (20) is also dry. Thereby cooling can take place in the fluid bed dryer without compromising the dryness of the material in the fluid bed dryer. Also significant advantages are obtained in the construction of the cooling systems of the present invention, including energy savings and bacterial growth prevention.
    An effect of the drying of the intake air in a desiccant dryer in particularly in the rotary desiccant wheel is that the heat of absorption stored by the water in the intake air is released such that intake air exiting e.g. the rotary desiccant wheel during operation exits as dried and warmed exit air. The cooling systems of the present invention must compensate for this effect in order to provide adequately cooled air to the fluid bed dryers as contemplated by the invention.
    Desiccant dehumidifiers comprise a range of different dehumidifiers with varying desiccants and constructive layouts to match the desiccant. Preferably contemplated for use with the present invention are liquid desiccants, silica gels, zeolites, and combinations thereof. Preferably, however, the desiccant dehumidifier is a rotary desiccant wheel comprising a solid state desiccant, preferably a silica gel, a zeolite, or a combination thereof.
    When the desiccant dehumidifier is a rotary desiccant wheel, the rotary desiccant wheels for use with the present invention operate according to known principles of operation of rotary desiccant wheels as they are usual in the art of drying moist intake air using rotary desiccant wheels. The present invention is detailed using rotary desiccant wheels (50) comprising only a process section (51) and a regeneration section (52) ; however, this is solely for exemplary use. The skilled person is aware that it is common to employ one or more purge zones for the operation of rotary desiccant wheels, and may employ such purge zones at his wish without departing from the scope of the present invention.
    Further comprised in the cooling system (2) comprising a dehumidifier, is at least one heating unit (54) for heating intake air to obtain heated regeneration air, which can be led to a regeneration section (52) of the dehumidifier, preferably the rotary desiccant wheel (50), along a regeneration air flow path (53).
    Accordingly, in an embodiment of the cooling system (2) of the invention there is disclosed a cooling system (2) further comprising a rotary desiccant wheel (50) arranged on said primary air flow path (41a, 41b) upstream from said indirect evaporative cooler (40), said rotary desiccant wheel (50) comprising a process section (51) and a regeneration section (52), said primary air flow path (41a,41b) traversing said rotary desiccant wheel (50) by said process section (51) ; said cooling system further comprising at least one regeneration air heating unit (54) for heating intake air to obtain heated regeneration air, which can be led to said regeneration section (52) of said rotary desiccant wheel (50), along a regeneration air flow path (53) , and at least one air moving unit for moving intake air and heated regeneration air along said regeneration air flow path (53).
    In order for sufficient regeneration of the rotary desiccant wheel (50) the regeneration air should be from about 50°C to about 150°C. Fortunately, which is an advantage of the present invention, numerous sources of reusable heat are present in a spray drying and fluid bed drying plant, wherefore the cost of supplying heated regeneration air is minimal when the plant is in operation. Nevertheless, diverse burners or electricity can be used to supply hot regeneration air from the at least one heating unit (54), however, this is less advantageous from an energy perspective.
    In an embodiment of the cooling system (2) further comprising a desiccant dehumidifier, but not detailed in the figure, the bypass air flow path (43) further connects directly to the secondary air flow path (42a) at a position upstream to said indirect evaporative cooler (40). Thereby the cooling capacity of the indirect evaporative cooler (40) can be augmented by dry primary air from the desiccant dehumidifier, e.g. the rotary desiccant wheel (50), thereby increasing the water absorptive capacity of the secondary air, and thereby its cooling capacity.
    Following the setup as detailed in figure 2, intake primary air enters the desiccant dryer, in the figure the rotary desiccant wheel (50), along a first stretch (41a) of the primary air flow path (41a, 41b). It is then dried and heated in the desiccant dryer (50), thereby becoming dried and heated primary air, before being transported along a second stretch (41b) of the primary air flow path (41a,41b) to the indirect evaporative cooler (40) . Upon traversing the dry side of the indirect evaporative cooler, the dried and heated primary air becomes dried and cooled intake air, whereupon it is directed to the fluid bed dryer (20) along the fluid bed dryer intake air flow path (21) .
    In Figure 3 there is detailed an embodiment of the present invention wherein the desiccant dehumidifier is regenerated using excess energy generated by other processes in the production plant wherein the systems of the invention are installed. In the figure, the at least one regeneration air heating unit (54) detailed in Figure 2 has been replaced, at least partially, by heat exchangers (54a,54b,54c) for recovery of heat stored in release air from the process elements, e.g. spray dryer (10) or fluid bed dryer (20), of the plant.
    In one embodiment the at least one regeneration air heating unit (54) is replaced by a regeneration air heat exchanger (54) located on one or more of the exhaust air flow paths (12,22) for release air of the spray dryer (10) and/or the fluid bed dryer (20).
    In one embodiment, the regeneration air heating unit (54) is partially replaced by a heat exchanger (54a) located downstream from the desiccant dehumidifier (50), in the preferred embodiment detailed in the drawing a rotary desiccant wheel, on said second stretch (41b) of said primary air flow path. Thereby some of the heat contained in the dried and warmed primary air is removed prior to the air entering the indirect evaporative cooler (40) , which will improve the cooling effect of that unit. The regeneration flow path (53) accordingly will cross the second stretch (41b) of the primary air flow path downstream from the desiccant dehumidifier.
    However, since only a fraction of the energy needed for regeneration of the desiccant dryer can be recovered in this manner, a supplementary heating unit (54) will still be needed. In one embodiment, this supplementary heating unit (54) is a conventional heating unit, i.e. a burner or an electrical heater; however, preferably the supplementary heating unit is a second heat exchanger as detailed below.
    It is namely one of the significant advantages of the present invention that heat for regeneration of the desiccant dehumidifiers used in the invention is readily available from the release air of the various process units (spray dryer (10), fluid bed dryer (20) etc.). In Figure 3, this is indicated by heat exchangers (54b,54c) located at positions on the spray dryer exhaust air flow path (12) and/or the fluid bed dryer exhaust air flow path (22) . The regeneration flow path (53) accordingly crosses these flow paths at the positions of the heat exchangers. When the heat exchanger (54a) located at a position on said second stretch (41b) of said primary air flow path is present, the regeneration temperature can be augmented by further heated air from heat exchangers (54b,54c) located elsewhere in the production plant.
    In general, where energy saving is in focus, the solutions comprising desiccant dryers regenerated using heat obtained by heat exchange from exhaust air is preferred. However, if the cooling systems of the present invention are to be installed in existing spray drying and fluid bed drying plants, requirements for space (footprint) and lack of possibility for installing additional heat exchangers on the exhaust air flow paths (12,22) from spray dryer (10) or fluid bed dryer (20) may necessitate a self-contained cooling system of the invention. In such self-contained cooling systems of the invention burners or electrical heaters may be the preferred options.
    In a further embodiment of the invention, independently of or in combination with the further embodiments of the invention, the secondary air is dried prior to its entry into the wet side of the indirect evaporative dryer (40). This is detailed in Figure 4.
    The secondary air is dried in at least one secondary air drying unit (60) positioned on said secondary air flow path (42a) upstream from said indirect evaporative dryer (40) . The at least one secondary air drying unit (60) preferably is a desiccant dehumidifier of the types discussed previously in the present disclosure.
    Drying the secondary air prior to its entry into the wet side of the indirect evaporative dryer has the added advantage of augmenting the cooling capacity of the secondary air, thereby allowing the system to produce either colder intake air for the fluid bed dryer (20) and/or allow a higher production rate of cooled intake air for the fluid bed dryer (20).
    Accordingly there is disclosed a cooling system (4) of the invention further comprising at least one secondary air drying unit (60) for heating the secondary air prior to traversing the wet side of the indirect evaporative dryer (4 0) .
    In a further embodiment of the invention, independently of or in combination with the further embodiments of the invention, the secondary air is heated prior to its entry into the wet side of the indirect evaporative dryer (40). This is detailed in Figure 5.
    In general, it is unnecessary to heat the secondary air prior to its entry into the wet side of the indirect evaporative dryer (40) as the dew point of the air is not changed by this action. However local climate restrictions may require heating and the embodiment is hereby included by example. However, the embodiments for secondary heating disclosed in connection with Figure 5 are, as will be detailed further below, with little modification very suitable for use with the above detailed drying of the secondary air and is disclosed supplementary to this as detailed further below.
    The secondary air is heated in at least one secondary air drying unit (64) positioned on said secondary air flow path (42a) upstream from said indirect evaporative dryer (40). The at least one secondary air heating unit (64) preferably is a desiccant dehumidifier (60) of the types discussed previously in the present disclosure.
    Heating and drying the secondary air prior to its entry into the wet side of the indirect evaporative dryer has the added advantage of augmenting the cooling capacity of the secondary air, thereby allowing the system to produce either colder intake air for the fluid bed dryer (20) and/or allow a higher production rate of cooled intake air for the fluid bed dryer (20) . Accordingly there is disclosed a cooling system (4) of the invention further comprising at least one secondary air drying unit (60) for heating the secondary air prior to traversing the wet side of the indirect evaporative dryer (40).
    In a one embodiment, the heating unit (64) is a heat exchanger. This is detailed in Figure 5 in combination, for exemplary reasons, with the embodiment wherein the cooling system of the invention further comprises a desiccant dehumidifier for drying the primary air.
    In one embodiment of the cooling system (5) of the invention further comprising at least one secondary air heating unit (64), the at least one secondary air heating unit being a secondary air heat exchanger (64) positioned on said secondary air flow path (42a) upstream from said indirect evaporative dryer (40) . The embodiment is detailed using the embodiment wherein the cooling system of the invention further comprises a desiccant dehumidifier for drying the primary air for the below reasons, can however just as easily be used independently thereof.
    One of the problems in drying the primary air in the desiccant dryer is the concomitant heating thereof. In one embodiment of the cooling system (5) further comprising a secondary air heat exchanger (64), the secondary air heat exchanger (64) and the primary air heat exchanger (54a) are identical. By crossing the primary (41b) and secondary (42a) air flow paths at this position, the primary air is advantageously cooled while the secondary air is advantageously heated and the cooling capacity of the indirect evaporative heater (40) is thereby augmented.
    In further embodiments, the secondary air heat exchanger (64) is a heat exchanger (54b, 54c) as indicated in the drawings where the secondary air heat exchanges with exhaust air from process equipment such as the spray dryer (54b) or the fluid bed dryer (54c) to gain advantage of the energy in form of heat stored in these flows of exhaust air. The secondary air flow path (42a) accordingly crosses these flow paths (12,22) at the positions of these heat exchangers (54b,54c).
    As detailed above it is further contemplated that the cooling system (1,2,3,4,5,6,7) shall comprise a secondary air dehumidifier, preferably a desiccant dehumidifier, and most preferably a rotary desiccant wheel dehumidifier, arranged on the secondary air flow path (42a) upstream from the indirect evaporative cooler (40). A cooling system (6) according to the invention comprising a secondary air dehumidifier (60) is detailed in Figure 6 using the most preferred embodiment, the rotary desiccant wheel, as an exemplary embodiment. As detailed in the figure, the secondary air dehumidifier (60) may be used together with the primary air dehumidifier (50) . It may however also be used without. When the secondary air dehumidifier (60) is a rotary desiccant wheel as detailed in the figure, the cooling system (6) further comprises at least one heating unit (64) for heating intake air to obtain heated regeneration air, which can be led to a regeneration section (62) of the dehumidifier, preferably the rotary desiccant wheel (60), along a regeneration air flow path (63), and a process air section (61) of the same rotary desiccant wheel in parallel to what was detailed above for the rotary desiccant wheel (50) for drying primary air.
    Accordingly, in an embodiment of the cooling system (6) of the invention there is disclosed a cooling system (6) further comprising a rotary desiccant wheel (60) arranged on said primary air flow path (42a) upstream from said indirect evaporative cooler (40), said rotary desiccant wheel (60) comprising a process section (61) and a regeneration section (62), said primary air flow path (42a) traversing said rotary desiccant wheel (60) by said process section (61); at least one regeneration air heating unit (64) for heating intake air to obtain heated regeneration air, which can be led to said regeneration section (62) of said rotary desiccant wheel (60), along a regeneration air flow path (63); and an air moving unit for moving intake air and heated regeneration air along said regeneration air flow path (63).
    As the secondary air exiting the desiccant dehumidifier will be dry, the cooling capacity of the secondary air is thereby significantly augmented. This in particular may be necessary if the cooling systems of the invention are installed in climates where the ambient air serving as secondary air is already hot and humid.
    In one embodiment, as detailed in Figure 6, the at least one secondary air heating unit (64) as detailed above, serves the purpose of the at least one regeneration air heating unit (64) . The unit will however no longer be located on said secondary air flow path (42a) but on said regeneration air flow path (63) .
    In one embodiment, the at least one regeneration air heating unit (54) and the at least one secondary air heating unit (64) forms a combined regeneration air and secondary air heating unit, and wherein the air flow paths for regeneration air (53,63) and/or the secondary air flow path (42) are split from each other only after passage of the combined regeneration air and secondary air heating unit. Thereby equipment and equipment footprint is saved. E.g. the exhaust air from the spray dryer (10) will typically contain far more energy in the form of heat as is necessary for optimal operation of cooling systems of the present invention. Therefore an air heat exchanger located at position 54b will usually generate enough heated supply air to the cooling systems of the invention such that any of the processes of the cooling systems requiring heated air in the cooling systems can all be adequately supplied from this one unit. Likewise, where space demands make heat exchange with other process equipment impractical or unfeasible, a single heating unit, e.g. a burner or an electrical heater, may take the place of the separate heating units (54,64) in the manner detailed above.
    In one embodiment of the invention, the cooling system (7) comprises only one desiccant dehumidifier which produces enough dry air to supply both the needs for primary air and for secondary air. As can be easily observed from Figure 6, the setup required to operate both desiccant dryers (50,60) are identical so it will be just as expedient to supply one desiccant dryer with the capacity to service both primary and secondary air needs.
    In the cooling system of this embodiment, both the primary air flow path (41) and the secondary air flow path (42) originate from the same source.
    This is detailed in an embodiment in Figure 7. In this embodiment of the invention, a rotary wheel desiccant dryer already forms part of the production plant as a means for supplying hot and dry air to the spray dryer (10) along a spray dryer drying air flow path (11) . A part of this dried air for the spray dryer (10) is then diverted as primary air and secondary air, along the primary (41) and secondary (42) air flow paths which are in fluid connection with the spray dryer drying air flow path (11), and used further downstream to cool the powderous material in the fluid bed dryer (20) after passage of the cooling system (7) of the invention.
    In the embodiments and aspects of the present invention it has been detailed above how cooling can be undertaken efficiently, and with an improved bacteriological risk profile, by using cooling systems incorporating an indirect evaporative cooler according to the embodiments of the invention.
    The invention has been detailed in connection with a fluid bed dryer, however, other drying systems and process equipment where simple, cheap and energy efficient cooling is needed can be used equally well with the cooling systems of the invention in lieu of the fluid bed dryer detailed herein.
    CLOSING COMMENTS
    The term "comprising" as used in the claims does not exclude other elements or steps. The term "a" or "an" as used in the claims does not exclude a plurality. A single processor or other unit may fulfill the functions of several means recited in the claims.
    The skilled person will know how to apply such necessary pipes and air ducts for transporting air through the system flow paths and/or water to the evaporative coolers as required. Likewise, a rotary desiccant wheel is dependent for its operation on adequate rotation of the wheel, which requires one or more motors for rotating the wheel. Other constructional elements for the proper operation may be necessary; however the skilled person will know how to employ such elements, while not detailed in the present application.
    Although the present invention has been described in detail for purpose of illustration, it is understood that such detail is solely for that purpose, and variations can be made therein by those skilled in the art without departing from the scope of the invention.
    权利要求:
    Claims (21)
    [1] CLAIMS :
    1. A cooling system (1,2,3,4,5,6,7) for supplying cooled intake air to a fluid bed dryer (20) for use as cooled intake air in cooling a warm or hot material to be dried in said fluid bed dryer (20); said cooling system (1,2,3,4,5,6,7) comprising: - an indirect evaporative cooler (40) comprising a dry side and a wet side; - a primary air flow path (41) connecting to said dry side upstream from said indirect evaporative cooler (40) ; — a secondary air flow path (42a, 42b) connecting to said wet side upstream and downstream of said indirect evaporative cooler (40), - a fluid bed dryer intake air flow path (21) connecting to said dry side downstream from said indirect evaporative cooler (40); said cooling system (1,2,3,4,5,6,7) - arranged to permit a flow of intake air for said fluid bed dryer to reach said dry side of said indirect evaporative cooler (40) as primary air along said primary air flow path (41); and — arranged to permit a flow of secondary air to reach said wet side of said same indirect evaporative cooler (40) along said secondary air flow path (42a); — permitting said primary air to traverse said dry side of said indirect evaporative cooler (40), thereby becoming cooled intake air; and — permitting said secondary air to traverse said wet side of said indirect evaporative cooler (40), thereby becoming cooled and moist secondary air/ and - supplying said cooled intake air to said fluid bed dryer (20) via said fluid bed dryer intake air flow path (21) connecting said dry side of said indirect evaporative cooler (40) to said fluid bed dryer (20) ; said cooling system (1,2,3,4,5,6,7) further comprising air moving units for moving air along said air flow paths (21,41,42a,42b).
    [2] 2. A cooling system (1,2,3,4,5,6,7) according to claim 1 further comprising a bypass air flow path (43) for directing and mixing a flow of primary air to said cooled intake air exiting said indirect evaporative cooler (40) at a first temperature to obtain cooled intake air of a second temperature, said second temperature higher than said first temperature.
    [3] 3. A cooling system (1,2,3,4,5,6,7) according to either claim 1 or claim 2 further comprising a redirection air flow path (44) for redirecting and/or mixing a flow of cooled primary air to said secondary air upstream from said indirect evaporative cooler (40) along said secondary air flow path (42a).
    [4] 4. A cooling system (2,3,5,6,7) according to any of the claims 1 to 3 further comprising a primary air dehumidifier (50), preferably a desiccant dehumidifier, and most preferably a rotary desiccant wheel, arranged on said primary air flow path (41a,41b) upstream from said indirect evaporative cooler (40) .
    [5] 5. A cooling system (2,3,5,6,7) according to claim 4 wherein said primary air dehumidifier is a rotary desiccant wheel (50) arranged on said primary air flow path (41a,41b) upstream from said indirect evaporative cooler (40) , said rotary desiccant wheel (50) comprising a process section (51) and a regeneration section (52), said primary air flow path (41a,41b) traversing said rotary desiccant wheel (50) by said process section (51); said cooling system further comprising at least one regeneration air heating unit (54) for heating intake air to obtain heated regeneration air, which can be led to said regeneration section (52) of said rotary desiccant wheel (50), along a regeneration air flow path (53), and at least one air moving unit for moving intake air and heated regeneration air along said regeneration air flow path (53) .
    [6] 6. A cooling system (2,3,5,6,7) according to claim 5 wherein said at least one regeneration air heating unit (54) has been replaced, at least partially, by heat exchangers (54a,54b,54c) for recovery of heat stored in release air.
    [7] 7. A cooling system (2,3,5,6,7) according to either claim 5 or claim 6 wherein said at least one regeneration air heating unit (54) is replaced by at least one regeneration air heat exchanger (54) located on one or more exhaust air flow paths (12,22) for release air from a spray dryer (10) and/or said fluid bed dryer (20) .
    [8] 8. A cooling system (2,3,5,6,7) according to either claim 5 or claim 6 wherein said at least one regeneration air heating unit (54) is partially replaced by a primary air heat exchanger (54a) located downstream from said rotary desiccant wheel (50) on a second stretch (41b) of said primary air flow path (41) augmented by a supplementary regeneration air heating unit located on said regeneration air flow path (53) between said heat exchanger (54a) and said rotary desiccant wheel (50).
    [9] 9. A cooling system (1,2,3,4,5,6,7) according to any of the previous claims wherein the secondary air is dehumidified prior to traversing said wet side of said indirect evaporative dryer (40).
    [10] 10. A cooling system (1,2,3,4,5,6,7) according to any of the previous claims further comprising a secondary air dehumidifier (60), preferably a desiccant dehumidifier, and most preferably a rotary desiccant wheel, arranged on said secondary air flow path (42a) upstream from said indirect evaporative cooler (40).
    [11] 11. A cooling system (4,6,7) according to claim 10 wherein said secondary air dehumidifier is a rotary desiccant wheel (60) arranged on said secondary air flow path (42a) upstream from said indirect evaporative cooler (40), said rotary desiccant wheel (60) comprising a process section (61) and a regeneration section (62), said secondary air flow path (42a) traversing said rotary desiccant wheel (60) by said process section (61); said cooling system further comprising at least one secondary air heating unit (64) for heating intake air to obtain heated regeneration air, which can be led to said regeneration section (62) of said rotary desiccant wheel (60), along a regeneration air flow path (63), and at least one air moving unit for moving intake air and heated regeneration air along said regeneration air flow path (63).
    [12] 12. A cooling system (4,5,6,7) according to claim 11 wherein said at least one secondary air heating unit (64) has been replaced, at least partially, by heat exchangers (54a,54b,54c) for recovery of heat stored in release air.
    [13] 13. A cooling system (4,5,6,7) according to either claim 11 or claim 12 wherein said at least one secondary air heating unit (64) is replaced by at least one secondary air heat exchanger (64) located on one or more exhaust air flow paths (12,22) for release air from a spray dryer (10) and/or said fluid bed dryer (20) .
    [14] 14. A cooling system (4,5,6,7) according to any of the claims 11 to 13 wherein said secondary air heat exchanger (64) and said primary air heat exchanger (54a) is one unit in which said primary (41b) and regeneration (63) air flow paths are crossing and heat exchanging, such that primary air is cooled while regeneration air is heated thereby augmenting the cooling capacity of said indirect evaporative heater (40) .
    [15] 15. A cooling system (2,3,4,5,6,7) according to any of the claims 4 to 14 wherein said at least one regeneration air heating unit (54) and said at least one secondary air heating unit (64) forms a combined regeneration air and secondary air heating unit, and wherein said air flow paths for regeneration air (53,63) and/or said secondary air flow path (42) are split from each other only after passage of said combined regeneration air and secondary air heating unit.
    [16] 16. A cooling system (2,3,4,5,6,7) according to any of the claims 4 to 15 further comprising only one desiccant dehumidifier, said desiccant dehumidifier having sufficient capacity to produce dry air to supply both the needs for primary air and for secondary air, and wherein said primary (41) and said secondary (42) air flow paths are split from each other only after passage of said only one desiccant dehumidifier.
    [17] 17. A cooling system (2,3,4,5,6,7) according to claim 16 wherein said only one desiccant dehumidifier is a rotary desiccant wheel supplying dry air for said spray dryer (10) along a spray dryer drying air flow path (11) and wherein said primary (41) and said secondary (42) air flow paths are in fluid connection with said spray dryer drying air flow path (11).
    [18] 18. A cooling system (1,2,3,4,5,6,7) according to any of the claims 1 to 17 wherein said material to be dried is a powderous material.
    [19] 19. A fluid bed dryer (20) comprising a cooling system (1,2,3,4,5,6,7) according to any of claims 1 to 18.
    [20] 20. An arrangement comprising a spray dryer (10) and a fluid bed dryer (20) sequentially arranged to allow transport of a material to be dried from said spray dryer (10) to said fluid bed dryer (20), said fluid bed dryer (20) comprising a cooling system (1,2,3,4,5,6,7) according to any of the claims 1 to 18.
    [21] 21. A method of supplying cooled intake air to a fluid bed dryer (20) for use as cooled intake air in cooling a warm or hot material to be dried in said fluid bed dryer (20); said method comprising in a cooling system according to any of the claims 1 to 18, supplying primary air along a primary air flow path (41) to a dry side of an indirect evaporative cooler (40), and secondary air along a secondary air flow path (42a,42b) to a wet side of said same indirect evaporative cooler (40); permitting said primary air to traverse said dry side of said indirect evaporative cooler (40), thereby becoming cooled intake air, and permitting said secondary air to traverse said wet side of said indirect evaporative cooler (40), thereby becoming cooled and moist secondary air; and supplying said cooled intake air to said fluid bed dryer (20) via a fluid bed dryer intake air flow path (21) connecting said dry side of said indirect evaporative cooler (40) to said fluid bed dryer (20) .
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    同族专利:
    公开号 | 公开日
    WO2017000967A1|2017-01-05|
    DK179273B1|2018-03-26|
    引用文献:
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    法律状态:
    2020-02-14| PBP| Patent lapsed|Effective date: 20190701 |
    优先权:
    申请号 | 申请日 | 专利标题
    DKPA201500373A|DK179273B1|2015-07-01|2015-07-01|A cooling system and a method of supplying cooled intake air to a fluid bed dryer|DKPA201500373A| DK179273B1|2015-07-01|2015-07-01|A cooling system and a method of supplying cooled intake air to a fluid bed dryer|
    PCT/DK2016/050231| WO2017000967A1|2015-07-01|2016-06-30|A cooling system and a method of cooling dry intake air to drying systems|
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