Dryer system

Abstract

A dryer system comprises a dryer (12), an absorbing device (24) for absorbing moisture from output air of the dryer using a liquid desiccant such that heated output air is produced, an evaporator (28) for evaporating water from the used liquid desiccant, a condenser (32) for condensing the evaporated water and exchanging heat with input air for the dryer, and a heat exchanger (50) for transferring heat from the heated output air to the input air for the dryer. The system increases energy efficiency and reduces the need for external heating sources.

Description

[0001] Dryer System

[0002] The technology relates to the field of drying systems, specifically dryers used for drying materials, in particular granular solid materials such as sand, wood chips, grains and cereals.

[0003] Dryers, such as kiln dryers, are widely used in various industries for removing moisture from solid. These dryers are commonly used in industries that handle solid materials in the form of powders or granules, both further referred to under the term granular solids. Examples where dryers are used are the chemical industry, agricultural industry, food industry, building industry, etc.

[0004] These dryers utilize heated air to remove moisture from the material to be dried. In the case of food, this drying may be done to improve the preservation and / or quality or to prepare the food for further processing. The heated air is typically generated by external heating sources, such as natural gas burners, electric heaters, or biomass heaters. The air is then circulated through the dryer, where it absorbs moisture from the products being dried. The moist output air is then exhausted from the dryer.

[0005] One of the main challenges in operating dryers is the high energy consumption associated with the external heating sources. This energy consumption not only increases the operational costs but also contributes to greenhouse gas emissions. To address this issue, heat recovery systems have been developed to recover and reuse the heat from the exhaust air of the kiln dryer. These systems typically employ heat exchangers to transfer heat from the exhaust air to the incoming air, thereby reducing the demand for external heating.

[0006] However, conventional heat recovery systems have certain limitations. The efficiency of heat exchangers is often limited by the amount of heat that can be recovered from the exhaust air. The heat exchanger can only (pre-)heat the input air using the exhaust air, at most up to a temperature that is lower than the output air temperature. Therefore, the input air will always have to be heated further to reach the desired temperature of the input air for the dryer. It is an object of the present patent disclosure to provide improved dryer systems, heat recovery systems, and drying methods.

[0007] According to a first aspect of the disclosure, a dryer system is provided that includes a dryer, an absorbing device, an evaporator, a condenser, and a heat exchanger. The absorbing device is designed to absorb moisture from the output air of the dryer using a liquid desiccant, resulting in heated output air. The evaporator is used to evaporate water from the used liquid desiccant. The condenser is designed to condense the evaporated water and exchange heat with the input air for the dryer. The heat exchanger is used to transfer heat from the heated output air to the input air for the dryer. The absorbing device, by absorbing the moisture from the output air, uses the latent heat of condensation of the water in the output air of the dryer to heat that output air. This system thus allows for efficient heat recovery and moisture removal, resulting in an improved energy efficiency of the system. The combination of features advantageously results in a reduced amount of external heating that is required for heating the input air to the desired input air temperature. Under some conditions, depending on ambient temperature, the system requires no external heating whatsoever.

[0008] The dryer may be configured to dry a material, such as a solid material, using heated input air. The material to be dried comprises water, which is at least partially removed from the material when drying. The solid may be a granular solid. The granular solid may be food, like grains or cereals. The dryer may be used for producing malt.

[0009] The dryer can be any device or system that uses heated input air, that is, warm air, and outputs air with increased humidity. Generally, the output air would have a lower temperature than the input air. The absorbing device uses the latent heat of condensation of the water in the output air of the dryer to heat that output air before its heat is extracted in the heat exchanger, so that it is not required that the output air has a lower temperature than the input air.

[0010] Optionally, in some examples, the dryer system includes a heat recovery system that comprises the absorbing device, the evaporator, the condenser, and the heat exchanger. This heat recovery system may be designed to efficiently recover and reuse heat from the drying process, enhancing the energy efficiency of the dryer system.

[0011] Optionally, in some examples, the dryer system includes a heater that provides additional heating to the input air received from the heat recovery system. This heater allows the input air to reach the desired temperature for the drying process, in case the heat recovery system does not provide sufficient heat. Whether or not this is the case may depend on temperature parameters, such as the ambient temperature, output air temperature from the dryer, and humidity level of the output air from the dryer.

[0012] Optionally, in some examples, the evaporator in the dryer system is configured to evaporate the water from the used liquid desiccant, resulting in regenerated liquid desiccant. The regenerated liquid desiccant has a lower water concentration than the used liquid desiccant. This regeneration process allows for the reuse of the liquid desiccant, reducing or eliminating the need for fresh desiccant.

[0013] Optionally, in some examples, the dryer system further includes a liquid desiccant container that is arranged in fluid communication with the absorbing device and the evaporator. The container allows for varying respective liquid desiccant flows between the absorber and the container and the container and the condenser independently.

[0014] Optionally, in some examples, the liquid desiccant container is arranged to receive the used liquid desiccant from the absorbing device and feed the liquid desiccant to the evaporator. This arrangement allows for a continuous supply of liquid desiccant to the evaporator, enabling the continuous operation of the dryer system.

[0015] Optionally, in some examples, the liquid desiccant container is arranged to receive the regenerated liquid desiccant from the evaporator and to feed the liquid desiccant to the absorbing device. This arrangement allows for a continuous supply of liquid desiccant to the absorbing device, enabling the continuous operation of the dryer system. Optionally, in some examples, the dryer system is configured to provide the regenerated liquid desiccant to the liquid desiccant container.

[0016] Optionally, in some examples, the condenser in the dryer system is configured to produce liquid water, wherein the dryer system is arranged to dilute the liquid desiccant entering the evaporator with at least a part of the produced liquid water. This feature allows for the control of the concentration of the liquid desiccant going to the evaporator. Also, when water is added to the liquid desiccant going from the liquid desiccant container to the evaporator, the liquid desiccant concentration in the container can be higher than the maximum desiccant concentration required by the evaporator. In turn, the absorber, receiving the liquid desiccant with higher concentration from the container, works more efficiently since higher concentration liquid desiccant results in more moisture to be removed from the output air of the dryer. In addition, when the dryer is not in use, e.g. when taking out dried material and thereafter refilling the dryer with wet material, the condenser, for which typically is startup and shutdown are preferably avoided, can advantageously remain online, while little or no water is produced by the absorber.

[0017] Optionally, in some examples, the dryer system comprises a second absorbing device arranged to absorb moisture from the input air for the dryer before the input air for the dryer is input to the heat exchanger and using a liquid desiccant such that the input air for the dryer is pre-heated. This second absorber will increase the energy efficiency of the dryer system, due to the heating. Additionally, the air input to the dryer has less moisture in it, such that the air can beneficially take up more moisture within the dryer.

[0018] Optionally, in some examples, the dryer system comprises a second liquid desiccant container, wherein the second absorbing device is in fluid communication with the second liquid desiccant container, and wherein the system is configured such that the second liquid desiccant container is arranged to receive (regenerated) liquid desiccant from the evaporator, and that the first liquid desiccant container is arranged to receive liquid desiccant from the second liquid desiccant container and to output liquid desiccant to the evaporator. Optionally, in some examples, the liquid desiccant used in the dryer system is a saltbased aqueous solution. This type of desiccant is highly effective in absorbing moisture, contributing to the efficient operation of the dryer system.

[0019] Optionally, in some examples, the salt-based aqueous solution used as the liquid desiccant is selected from a group consisting of various types of solutions, including potassium acetate-based solution, calcium chloride-based solution, sodium sulfate- based solution, lithium bromide-based solution, potassium carbonate-based solution, sodium chloride-based solution, potassium chloride-based solution, magnesium chloride-based solution, calcium chloride-based solution, ammonium chloride-based solution, zinc chloride-based solution, lithium chloride-based solution, and iron chloride-based solution. This variety of options allows for the selection of the most suitable desiccant for specific drying conditions, providing flexibility and control over the drying process.

[0020] Optionally, in some examples, the absorbing device used in the dryer system is selected from a group consisting of a spray tower absorber, a falling film absorber, and a plate heat exchanger absorber. These different types of absorbers provide options for the most suitable device for specific drying conditions, providing flexibility and control over the drying process.

[0021] Optionally, in some examples, the heater used in the dryer system is selected from a group consisting of an electric heater, a gas heater, a natural gas heater, a methane gas heater, and a biomass heater. These different types of heaters provide options for the most suitable heat source for specific drying conditions and energy availability, providing flexibility and control over the drying process.

[0022] Optionally, in some examples, the dryer used in the dryer system is configured to dry foodstuff using warm air. This feature allows for the drying of a wide range of food products, making the dryer system versatile and adaptable to different industrial applications.

[0023] Optionally, in some examples, the dryer used in the dryer system may be either a continuous dryer or a batch dryer. The dryer may be a kiln dryer, a conveyor dryer, a rotary dryer, a belt dryer, a spray dryer, or a flash dryer. These different types of dryers provide options for the most suitable dryer for specific drying conditions and product types, providing flexibility and control over the drying process.

[0024] Optionally, in some examples, the heat exchanger in the dryer system comprises an air-to-liquid heat exchanger and a liquid-to-air heat exchanger. The air-to-liquid heat exchanger is configured to transfer heat from the heated output air to a heat transfer liquid, and the liquid-to-air heat exchanger is configured to transfer heat from the heat transfer liquid to the input air for the dryer. This arrangement allows for efficient heat transfer and recovery, contributing to the energy efficiency of the dryer system.

[0025] Optionally, in some examples, the heat exchanger in the dryer system further comprises a liquid-to-liquid heat exchanger that is configured to transfer heat from the condensed water to the heat transfer liquid coming from the air-to-liquid heat exchanger. This feature allows for additional heat recovery from the condensed water, further enhancing the energy efficiency of the dryer system.

[0026] According to a second aspect of the disclosure, a heat recovery system for a dryer is provided. The system includes an absorbing device, an evaporator, a condenser, and a heat exchanger. The absorbing device is configured to absorb moisture from output air of the dryer using a liquid desiccant such that heated output air is produced. The evaporator is in fluid communication with the absorbing device and is configured to evaporate water from the liquid desiccant. The condenser is configured to condense the evaporated water and exchange heat with the input air for the dryer. The condenser is also configured to produce liquid water, and the heat recovery system is configured to dilute the liquid desiccant entering the evaporator with the produced liquid water. The heat exchanger arranged to transfer heat from the heated output air to the input air for the dryer. This system allows for efficient heat recovery and moisture removal, resulting in energy savings and improved drying performance.

[0027] The absorbing device, by absorbing the moisture from the output air, uses the latent heat of condensation of the water in the output air of the dryer to heat that output air. This system thus allows for efficient heat recovery and moisture removal, resulting in an improved energy efficiency of the system. The combination of features advantageously results in a reduced amount of external heating that is required for heating the input air to the desired input air temperature. Under some conditions, depending on ambient temperature, no external heating whatsoever is required for heating the input air for the dryer.

[0028] Optionally, in some examples, the heat recovery system further includes a liquid desiccant container that is arranged in fluid communication with the absorbing device and the evaporator. The container allows for varying respective liquid desiccant flows between the absorber and the container and the container and the condenser independently.

[0029] Optionally, in some examples, the liquid desiccant container is arranged to receive the used liquid desiccant from the absorbing device and feed the liquid desiccant to the evaporator. This arrangement allows for a continuous supply of liquid desiccant to the evaporator, enabling the continuous operation of the evaporator, also, for instance, when the dryer and / or absorber is offline.

[0030] Optionally, in some examples, the liquid desiccant container is arranged to receive the regenerated liquid desiccant from the evaporator and feed the liquid desiccant to the absorbing device. This allows for the respective flows of liquid desiccant from the container to the absorber and from the container to the evaporator to be different, if so required or desired.

[0031] According to a third aspect of the disclosure, a method for a dryer system is provided. The method includes absorbing moisture from the output air of a dryer using a liquid desiccant in an absorbing device to produce heated output air, evaporating water from the used liquid desiccant in an evaporator, condensing the evaporated water in a condenser and exchanging heat with the input air for the dryer, and transferring heat from the heated output air to the input air for the dryer in a heat exchanger. This method allows for efficient heat recovery and moisture removal, resulting in energy savings and improved drying performance.

[0032] Optionally, in some examples, the method includes diluting the liquid desiccant entering the evaporator with liquid water produced by the condenser. This feature allows for the control of the concentration of the liquid desiccant going to the evaporator. Also, when water is added to the liquid desiccant going from the liquid desiccant container to the evaporator, the liquid desiccant concentration in the container can be higher than the maximum desiccant concentration required by the evaporator. In turn, the absorber, receiving the liquid desiccant with higher concentration from the container, works more efficiently since higher concentration liquid desiccant results in more moisture to be removed from the output air of the dryer. In addition, when the dryer is not in use, e.g. when taking out dried material and thereafter refilling the dryer with wet material, the condenser, for which typically is startup and shutdown are preferably avoided, can advantageously remain online, while little or no water is produced by the absorber.

[0033] Optionally, in some examples, the method further includes providing additional heating to the input air for the dryer using a heater. This step allows the input air to reach the desired temperature for the drying process, providing flexibility and control over the drying conditions.

[0034] Optionally, in some examples, the method includes receiving the used liquid desiccant from the absorbing device in a liquid desiccant container and feeding the liquid desiccant to the evaporator. This step allows for a continuous supply of liquid desiccant to the evaporator, enabling the continuous operation of the dryer system.

[0035] Optionally, in some examples, the method includes receiving regenerated liquid desiccant from the evaporator in the liquid desiccant container and feeding the liquid desiccant to the absorbing device. This step allows for a continuous supply of regenerated liquid desiccant to the absorbing device, enabling the continuous operation of the dryer system.

[0036] Optionally, in some examples, the method includes pumping the regenerated liquid desiccant to the liquid desiccant container. This step allows for the efficient transport of regenerated liquid desiccant, ensuring its availability for use in the absorbing device and contributing to the overall efficiency of the dryer system. It will be understood that technical advantages and effects associated with features and / or features mentioned in relation to one aspect, apply to the corresponding, similar or equivalent features of the other aspects. It will also be apparent that the features of the various aspects and / or examples thereof may be applied to the other aspects and / or examples thereof.

[0037] Brief Description of Figures

[0038] Examples are described in more detail below with reference to the appended drawings. Figure 1 is a schematic diagram of an example of the improved dryer system.

[0039] Figure 2 is a schematic diagram of another example of the improved dryer system.

[0040] Figure 3 is a graph showing various temperatures of the system as a function of the ambient temperature.

[0041] Figure 4 is a graph showing various temperatures versus time in the system during use, including a measured temperature of the output air from the kiln going into the absorber, a measured temperature of the heated air coming from the absorber at the inlet of the heat exchanger, and the ambient air temperature.

[0042] Figure 5 is a schematic diagram of an example dryer system.

[0043] Figure 6 is a schematic diagram of another example dryer system.

[0044] Detailed Description

[0045] The detailed description set forth below provides information and examples of the disclosed technology with sufficient detail to enable those skilled in the art to practice the disclosure.

[0046] Figure 1 shows a schematic diagram of the improved dryer system 10. The system includes a dryer 12, an absorbing device 24 for absorbing moisture from the output air of the dryer using a liquid desiccant, an evaporator 28 for evaporating water from the used liquid desiccant, a condenser 32 for condensing the evaporated water and exchanging heat with input air for the dryer, and a heat exchanger 50 for transferring heat from the heated output air to the input air for the dryer. The system also includes a heater 60 for providing additional heating to the input air received from the heat recovery system 20, and a liquid desiccant container 36 arranged in fluid communication with the absorbing device 24 and the evaporator 28.

[0047] The dryer system 10 includes sensors, which in the example of Figures 1 and 2 include a first temperature sensor 101 for measuring the temperature of the ambient air 80, a second temperature sensor 103 for measuring the temperature of the heated air output from the heat exchanger 50, a third temperature sensor 104 for measuring the temperature of the heated air going into the condenser 32, a fourth temperature sensor 105 for measuring the temperature of the heated air output by the condenser 32 for input into the heater 60, a fifth temperature sensor 106 for measuring the temperature of the heated air output by the heater 60 for input into the drying kiln 12, a sixth temperature sensor 107 for measuring the temperature of the output air coming from the drying dryer 12 for input to the absorbing device 24, a seventh temperature sensor 109 for measuring the temperature of the heated air coming from the absorbing device 24 for input to the source side of the heat exchanger 50, and an eighth temperature sensor 110 for measuring the temperature of the cooled air 82 coming from the heat exchanger 50. A selection of these temperature sensors may be used, or even more sensors may be used, depending on the dryer system. Further sensors other than temperature sensors may also be used, such as humidity sensors and pressure sensors. These are not shown in the schematic drawings but may be part of the dryer system.

[0048] Example dryer system 200 shown in Figure 2 may be the same as system 10 other than the following. In system 200, the heat exchanger 50 comprises an air-to-liquid heat exchanger 52, a liquid-to-air heat exchanger 54, and a liquid-to-liquid heat exchanger 56. The air-to-liquid heat exchanger 52 is configured to transfer heat from the heated output air to a heat transfer liquid. The liquid-to-air heat exchanger 54 is configured to transfer heat from the heat transfer liquid to the input air for the dryer 12. The liquid-to-liquid heat exchanger 56 is configured to transfer heat from the condensed water to the heat transfer liquid coming from the air-to-liquid heat exchanger 52.

[0049] The liquid water output is indicated with number 84 in Figures 1 and 2, and may be used for any desired purpose. It is, in most cases, of drinking water quality. The heat exchanger 50 in Figure 1 may comprise an air-to-liquid heat exchanger coupled to a I iquid-to-air heat exchanger, like heat exchanger 50 of Figure 2, but without the liquid- to-liquid heat exchanger 56.

[0050] Example dryer system 500 shown in Figure 5 may be the same as system 10 or 200. In the system 500, the heat recovery system 520 further comprises a second absorbing device 90 that takes the ambient air 80 as input and absorbs moisture from the ambient air such that the ambient air is heated by the latent heat of absorption of the moisture. The second absorbing device 90 may be configured or of the same type as absorbing device 24. The second absorbing device 90 is configured to output pre-heated ambient air to the heat exchanger 50. The second absorbing device 90 may be in fluid communication with the liquid desiccant container 36. The second absorbing device 90 will increase the energy efficiency of the dryer system. Additionally, the air input to the dryer has less moisture in it, such that the air can beneficially take up more moisture within the dryer. The system 200 may also comprise the second absorber 90 for preheating the input ambient air. In some examples, the dryer system according to the present patent disclosure may comprise only the second absorbing device 90 and not the absorbing device 24, only the absorbing device 24 and not the absorbing device 90, or both.

[0051] Example dryer system 600 shown in Figure 6 may be the same as system 500. In the system 600, the heat recovery system 620 comprises in additional to the second absorbing device 90 a second liquid desiccant container 38. The second absorbing device 90 may be in fluid communication with the second liquid desiccant container 38 in order to receive liquid desiccant and to return the liquid desiccant with increased water content to the second liquid desiccant container 38. The first absorbing device 24 is in fluid communication with the (first) liquid desiccant container 36. The second absorbing device 90 will increase the energy efficiency of the dryer system.

[0052] The second liquid desiccant container 90 is arranged such that, when in use, to receive liquid desiccant from the evaporator 28. This liquid desiccant has the lowest water concentration. This is beneficial because the relative humidity of the ambient air, from which the water is condensed in the second absorbing device 90, is lower than the relative humidity of the output air coming from the dryer 12. The second liquid desiccant container 38 in this example is configured to output liquid desiccant to the first liquid desiccant container 36, from which the first absorbing device 24 receives liquid desiccant. In this example, the liquid desiccant container 36, in use, comprises liquid desiccant with a higher water concentration than the second liquid desiccant container 38. In turn, the first liquid desiccant container 36 is configured to output liquid desiccant to the evaporator 28. This configuration increases the overall efficiency of the system, wherein the ambient air (by the latent heat of absorption of the humidity in the ambient air) can be heated more than in the configuration of system 500 of Figure 5.

[0053] Figure 3 is a graph showing various temperatures of the system as a function of the ambient temperature. The temperature of the output air from the dryer, as measured by sensor 107, is indicated and is stable at 30 °C, since it depends on the conditions in the dryer 12, which are, in the present example, independent of the ambient conditions. This dryer air output temperature of 30 °C is what is obtained for an input temperature of 65 °C, in this example. The output air from the dryer 12 has a relative humidity of about 95%.

[0054] Further indicated in Figure 3 are the temperatures measured by sensors 103 and 105, respectively. Sensor 103 measures the temperature of the heated ambient air coming from the heat exchanger 50, which is led to condenser 32 for further heating. As can be seen, for an ambient air temperature of 0 °C, the temperature of the heated ambient air is about 36 °C. For an ambient temperature of 40 °C, the temperature of the heated ambient air is about 42 °C. Thereafter, the heated ambient air coming from the heat exchanger 50, in the example of Figure 2 from the liquid-to-air heat exchanger 54, is led towards condenser 32, where it is further heated to the temperatures as measured by sensor 105.

[0055] The data of Figures 3 and 4 is associated with a dryer system comprising a dryer that is configured to dry the solid material with air having an input temperature of 65 °C. The ambient air is thus first heated using the heat exchanger 50, thereafter further heated using the condenser 32, and finally, if the desired temperature has not yet been reached, further heated to 65 °C with the heater 60. These temperature data will be the same or similar for other dryers for which the input air temperature is the same or similar, respectively. This would not change the heat recovery system. The temperature range to which input air for a dryer is heated, at least partially by the herein described heat recovery system, is in the range of 10 to 80 °C, depending on the ambient temperature and the efficiency of the heat exchanger 50. Other gases than air may be used, such as inert gases, e.g. nitrogen or argon, in case a material sensitive to oxidation is intended to be dried.

[0056] In the kiln dryer system used to obtain these data of Figures 3 and 4 and Table 1 below, the absorber comprises absorption pads along which the liquid desiccant is able to flow. The output air from the dryer flows through or along the absorption pads and thus the moisture from the output air is absorbed by the liquid desiccant present on or in the absorption pads. The liquid desiccant and absorption pads heat up due to the latent heat of condensation and thereby heat the air surrounding, or passing through, the pads. Other types of absorbers are able to function in a similar way. One example of a suitable pad is GlasPad and CelPad 0760 from Hutek.

[0057] Figure 4 is a graph showing various temperatures versus time, as measured in the morning from 8:30 to 11 :00. The ambient air temperature as measured by sensor 101 is indicated. Also, the temperature of the output air from the dryer 12 going into the absorber 24, as measured by sensor 107, and the temperature of the heated ambient air coming from the heat exchanger 50, as measured by sensor 103, are indicated.

[0058] As can be seen, the ambient temperature increases from about 14 °C at 8:30 in the morning to about 20 °C at 11 :00. From 8:30 to about 9:45, the system is started, after which a generally continuous operation follows. During the startup phase, between 8:30 and 8:45, the heat exchanger heats up the ambient air to temperatures in the range 21 °C to 25 °C. The heat exchanger is in turn heated by the heated output air coming from the absorber, which is heated due to the latent heat of condensation of the moisture from the output air heating up the output air while the moisture is removed.

[0059] During stable operation after 9:45, the temperature 107 of the output air from the dryer reaches about 30 °C and the output air relative humidity is about 95%. The use of the absorber results in the ambient air to be heated to about 35 °C. The heated ambient air, with a temperature of about 35 °C is then input into the condenser 32. Table 1 : Various temperature and power parameters of the dryer system in relation to the ambient air temperature for a dryer system that processes 500,000 kg of air per hour.

[0060] Table 1 shows the air temperature obtained from the heat recovery system, the heat power obtained from the heat recovery system, the power required for further heating with the heater 60, and the total power needed to reach 65 °C for the input air for the dryer 12, all versus the temperature of the ambient air. As can be seen, with increasing ambient temperature, less additional heat provided by the heater 60 is required other than the heat provided by the heat recovery system 20. At 30 °C ambient temperature, there is no need for additional heat from the heater 60.

[0061] Dryer System Details

[0062] The dryer system 10, as disclosed in the disclosure, can be used to dry various materials, such as foodstuffs, wood, and other substances. The system is designed to have an increased energy efficiency, making it an environmentally friendly solution for drying needs. The dryer system 10 may comprise several components, each with a specific function that contributes to the overall efficiency and effectiveness of the system. The heat recovery system 20 is a component of the dryer system 10. In some examples, the heat recovery system 20 is designed to recover and utilize the heat energy that would otherwise be lost. This is achieved through a series of components that work together to absorb moisture from the output air, evaporate water from the used liquid desiccant, condense the evaporated water, and transfer the recovered heat to the input air for the dryer. The heat recovery system 20 may comprise an absorbing device 24, an evaporator 28, a condenser 32, and a heat exchanger 50.

[0063] The absorbing device 24 is a component of the heat recovery system 20. In some examples, the absorbing device 24 is designed to absorb moisture from the output air of the dryer using a liquid desiccant. This process not only removes moisture from the air but also releases latent heat from the absorbed moisture, thereby increasing the temperature of the heated air. The absorbing device 24 may be of various types, such as a spray tower absorber, a falling film absorber, a plate heat exchanger absorber, or a cross-flow absorber. The cross-flow absorber may comprise one or more absorption pads as described above. An aqueous potassium acetate-based liquid desiccant was used as the liquid desiccant.

[0064] The evaporator 28 is another component of the heat recovery system 20. In some examples, the evaporator 28 is designed to evaporate water from the used liquid desiccant, thereby regenerating the desiccant for reuse and producing evaporated water for heat exchange in the condenser. The evaporator 28 is in fluid communication with the liquid desiccant container 36 and the absorbing device 24.

[0065] The evaporation heater may be a component of the evaporator 28. In some examples, the evaporation heater is designed to heat the liquid desiccant to evaporate water. This process lowers the water concentration in the liquid desiccant, thereby enhancing or restoring the desiccant’s ability to absorb moisture from the output air in the absorbing device 24.

[0066] A vacuum pump (not shown) may be another component of the evaporator 28. In some examples, the vacuum pump is configured to reduce the pressure in the evaporator. This reduction in pressure lowers the temperature of evaporation or boiling temperature of water from the liquid desiccant, thereby reducing the required heating energy required in the regeneration of the liquid desiccant for reuse in the absorbing device 24.

[0067] The condenser 32 is a component of the heat recovery system 20. In some examples, the condenser 32 is designed to use the latent heat in the evaporated water to heat the input air for the dryer. This process increases the energy efficiency of the dryer system 10. The condenser 32 receives heated air from the heat exchanger. The condenser 32 is also designed to produce liquid water 84, which can optionally be used to dilute the liquid desiccant entering the evaporator and / or as a heat source in or for the liquid-to-liquid heat exchanger 56.

[0068] The liquid desiccant container 36 is a component of the heat recovery system 20. In some examples, the liquid desiccant container 36 is designed to receive the used liquid desiccant from the absorbing device 24 and feed it to the evaporator 28. This arrangement allows for different flow rates between the absorbing device 24 and the container 36, and between the container 36 and the evaporator 28, thereby enhancing the efficiency of the heat recovery process. The liquid desiccant container 36 may also receive the regenerated liquid desiccant from the evaporator 28 and feed it back to the absorbing device 24 for reuse.

[0069] The liquid desiccant is an element in the heat recovery system 20. In some examples, the liquid desiccant is a solution that is capable of absorbing moisture from the output air in the absorbing device 24. The liquid desiccant may be a salt-based aqueous solution or a glycerol-based solution. Examples of salt-based aqueous solutions include potassium acetate-based solution, calcium chloride-based solution, sodium sulfate-based solution, lithium bromide-based solution, potassium carbonate-based solution, sodium chloride-based solution, potassium chloride-based solution, magnesium chloride-based solution, calcium chloride-based solution, ammonium chloride-based solution, zinc chloride-based solution, and iron chloride-based solution. The liquid desiccant is regenerated in the evaporator 28 by evaporating water from it, and the regenerated liquid desiccant is then pumped back to the absorbing device 24 for reuse. The liquid desiccant fed to the absorber preferably comprises the salt at a concentration close to, but not equal to, the maximum solubility of the salt in water. The evaporator requires a lower salt concentration, so that water can be evaporated from the liquid desiccant. For potassium acetate based aqueous solutions, the concentration of the salt in the liquid desiccant is preferably between 57 wt% and 70 wt% salt per total weight of the liquid desiccant.

[0070] The heat exchanger 50 is a component of the heat recovery system 20. In some examples, the heat exchanger 50 is designed to transfer heat from the heated air in the absorber to the input air for the dryer, thereby increasing the temperature of the input air. The heat exchanger 50 may comprise an air-to-liquid heat exchanger 52 and a liquid-to-air heat exchanger 54. In some examples, the heat exchanger 50 may further comprise a liquid-to-liquid heat exchanger 56. The air-to-liquid heat exchanger 52 transfers heat from the heated output air to a heat transfer liquid. The liquid-to-air heat exchanger 54 transfers heat from the heat transfer liquid to the input air for the dryer and outputs cooled heat transfer liquid back towards the air-to-liquid heat exchanger. The liquid-to-liquid heat exchanger 56 transfers heat from the condensed water to the heat transfer liquid coming from the air-to-liquid heat exchanger 52.

[0071] The heat source side of the heat exchanger 50 is where the heated air from the absorber enters the heat exchanger. In some examples, the heat source side of the heat exchanger 50 comprises an air inlet and an air outlet. The air inlet of the heat source side of the heat exchanger 50 is designed to receive the heated air from the absorber. In some examples, the air inlet receives the heated air that has been increased in temperature by the absorbing device 24 through the release of latent heat from the absorbed moisture. The air outlet of the heat source side of the heat exchanger 50 is designed to release the cooled air from the heat exchanger. In some examples, the air outlet releases the air after it has transferred its heat to the heat transfer liquid in the air-to-liquid heat exchanger 52.

[0072] The heat sink side of the heat exchanger 50 is where the input air for the dryer is heated. In some examples, the heat sink side of the heat exchanger 50 comprises an air inlet and an air outlet. The air inlet of the heat sink side of the heat exchanger 50 is designed to receive air to be heated by the heat exchanger. In some examples, the air inlet receives ambient air 80, optionally pre-heated by the second absorber 90. In some examples, the air outlet outputs the air after it has been heated by the heat transfer liquid in the liquid-to-air heat exchanger 54. The heated air is then directed towards the dryer for the drying process.

[0073] The at least one liquid desiccant pump (not shown) is a component of the heat recovery system 20. In some examples, the liquid desiccant pump is arranged to pump the liquid desiccant from the liquid desiccant container 36 to and from the absorbing device 24. In some examples, the at least one liquid desiccant pump is arranged to pump liquid desiccant from the liquid desiccant container 36 to and from the second absorbing device 90. The at least one liquid desiccant pump may comprise a plurality of liquid desiccant pumps to pump between each of the components, such as a pump for pumping between the liquid desiccant container and the absorbing device 24, a pump for pumping between the liquid desiccant container 36 and the evaporator 28, and a pump for pumping between the liquid desiccant container 36 and the second absorbing device 90. The at least one liquid desiccant pump may also pump the liquid desiccant from the liquid desiccant container 36 to and from the condenser 32. The pump allows for the flow of the liquid desiccant through the system. There may be a separate pump for pumping liquid desiccant from the liquid desiccant container to absorber and vice versa and for pumping the liquid desiccant from the liquid desiccant container to the evaporator and vice versa, respectively.

[0074] The heater 60 is a component of the dryer system 10. In some examples, the heater 60 is designed to provide external heating to the input air coming from the heat recovery system 20 for the dryer in order to obtain the required temperature. The required temperature for the input air in the dryer may be between 50 °C and 100 °C, e.g. 50 °C to 80 °C depending on the specific drying requirements. The heater 60 may be an electric heater, a gas heater, a natural gas heater, a methane gas heater, or a biomass heater.

[0075] The dryer 12 is a component of the dryer system 10. In some examples, the dryer 12 is designed to dry wet materials, such as solid materials, using warm air. The dryer 12 may be a kiln dryer, a conveyor dryer, a rotary dryer, a belt dryer, a spray dryer, or a flash dryer. The type of dryer used may depend on the specific drying requirements and the type of material to be dried.

[0076] The dryer system 10 may comprise several sensors that monitor various parameters of the system. These sensors provide data that can be used to control the operation of the system and allow for efficient performance.

[0077] The method of using the heat recovery system 20 in the dryer system 10 involves a series of steps that are designed to increase the efficiency of the drying process. These steps involve the flow of air and liquid desiccant through the system, the absorption of moisture from the output air, the transfer of heat from the heated air to the input air, and the optional additional heating of the input air.

[0078] The air flow process in the heat recovery system 20 involves several steps. In some examples, these steps include receiving input air for the dryer in the heat exchanger 50, transferring heat from the heated air in the absorbing device to the input air to increase its temperature, outputting the heated air from the heat exchanger towards the dryer, receiving the output air from the dryer into the absorbing device 24, absorbing moisture from the output air using the liquid desiccant in the absorbing device, releasing latent heat from the absorbed moisture to increase the temperature of the heated air, and receiving the heated output air from the absorbing device 24 into the heat exchanger 50.

[0079] The absorption of moisture from the output air is a step in the air flow process in the heat recovery system 20. In some examples, this step involves receiving the output air from the dryer into the absorbing device 24 and absorbing moisture from the output air using the liquid desiccant. This process not only removes moisture from the air but also releases latent heat from the absorbed moisture, thereby increasing the temperature of the heated air.

[0080] The transfer of heat from the heated air to the input air is a step in the air flow process in the heat recovery system 20. In some examples, this step involves receiving the input air for the dryer in the heat exchanger 50 and transferring heat from the heated air in the absorbing device to the input air. This process increases the temperature of the input air, thereby enhancing the efficiency of the drying process.

[0081] The additional heating of the input air is an optional step in the air flow process in the heat recovery system 20. In some examples, the heater 60 may provide additional heating to the input air received from the heat recovery system 20 for the dryer in order to obtain the required temperature. This process allows the system to achieve the desired temperature for the drying process.

[0082] The flow of liquid desiccant in the heat recovery system 20 involves several steps. In some examples, these steps include pumping the liquid desiccant from the liquid desiccant container 36 to the absorbing device 24, absorbing moisture from the output air in the absorbing device using the liquid desiccant, pumping the used liquid desiccant from the absorbing device to the liquid desiccant container, pumping the liquid desiccant from the liquid desiccant container to the evaporator, evaporating water from the liquid desiccant in the evaporator to produce regenerated liquid desiccant, and pumping the regenerated liquid desiccant back to the liquid desiccant container. The evaporated water may be condensed in the condenser, while exchanging heat with the input air for the dryer. Optionally, some or all of the condensed water is used to dilute the liquid desiccant entering the evaporator. In addition, or alternatively, and optionally, some or all of the condensed water, when it is still warmer than the heated output air used for the heat exchanger, is used in the liquid-to-liquid heat exchanger 56.

[0083] In one example, the dryer system 10 may comprise a heat recovery system 20 that includes an absorbing device 24, an evaporator 28, a condenser 32, and a heat exchanger 50. The absorbing device 24 may be designed to absorb moisture from the output air of the dryer using a liquid desiccant, thereby producing heated output air. The evaporator 28 may be designed to evaporate water from the used liquid desiccant, thereby regenerating the desiccant for reuse. The condenser 32 may be designed to condense the evaporated water and exchange heat with the input air for the dryer. The heat exchanger 50 may be designed to transfer heat from the heated output air to the input air for the dryer. In another example, the dryer system 10 may further comprise a heater 60 for providing additional heating to the input air received from the heat recovery system 20. The heater 60 may be an electric heater, a gas heater, a natural gas heater, a methane gas heater, or a biomass heater. The heater 60 may be designed to provide the required temperature for the input air in the dryer, which may be between 50°C and 80°C.

[0084] In yet another example, the dryer system 10 may further comprise a liquid desiccant container 36 arranged in fluid communication with the absorbing device 24 and the evaporator 28. The liquid desiccant container 36 may be designed to receive the used liquid desiccant from the absorbing device 24 and feed it to the evaporator 28. The liquid desiccant container 36 may also receive the regenerated liquid desiccant from the evaporator 28 and feed it back to the absorbing device 24 for reuse.

[0085] The dryer system 10, with its heat recovery system 20, can be used in a variety of applications where drying is required. The system’s ability to recover and utilize heat energy that would otherwise be lost in the drying process makes it an energy-efficient and environmentally friendly solution for drying needs.

[0086] In one example, the dryer system 10 can be used in the food processing industry. The system can be used to dry various foodstuffs, such as grains, cereals, fruits, and vegetables.

[0087] In another example, the dryer system 10 can be used in the wood processing industry. The system can be used to dry timber, wood chips, and sawdust.

[0088] In yet another example, the dryer system 10 can be used in other industries where drying is required, such as the pharmaceutical industry, the chemical industry, and the textile industry.

[0089] In some examples, the dryer 12 used in the dryer system 10 can be a kiln dryer, a conveyor dryer, a rotary dryer, a belt dryer, a spray dryer, or a flash dryer. The type of dryer used can depend on the specific drying requirements and the type of material to be dried. In conclusion, the dryer system 10, with its heat recovery system 20, provides an energy-efficient and environmentally friendly solution for drying needs. The system’s ability to recover and utilize heat energy that would otherwise be lost in the drying process, makes it an ideal solution for a variety of applications.

[0090] The dryer systems of the present application have been described in the field of drying of food stuffs, such as malt, but it will be understood that the present drying system can be used anywhere where there is a need for heated air for drying, i.e. in a dryer, and where moisture can be absorbed by which the air stream from which the moisture is absorbed is heated, and also beneficially that air thereafter has a lower humidity.

[0091] The present patent disclosure further comprises the following examples.

[0092] Example 1 . A dryer system comprising: a dryer configured to dry a material using heated input air, an absorbing device arranged to absorb moisture from output air of the dryer using a liquid desiccant such that heated output air is produced, an evaporator arranged in fluid communication with the absorbing device and configured to evaporate water from the used liquid desiccant, a condenser arranged to condense the evaporated water and exchanging heat with input air for the dryer, and a heat exchanger arranged to transfer heat from the heated output air to the input air for the dryer.

[0093] Example 2. The dryer system according to example 1 , comprising a heat recovery system including the absorbing device, the evaporator, the condenser and the heat exchanger.

[0094] Example 3. The dryer system according to example 2, comprising a heater for providing additional heating to the input air received from the heat recovery system. Example 4. The dyer system according to examples 1 , 2 or 3, wherein the evaporator is configured to evaporate the water from the used liquid desiccant such that regenerated liquid desiccant is produced.

[0095] Example 5. The dryer system according to examples 1 to 4, further comprising a liquid desiccant container arranged in fluid communication with the absorbing device and the evaporator.

[0096] Example 6. The dryer system according to example 5, the liquid desiccant container is arranged to receive the used liquid desiccant from the absorbing device and feed the liquid desiccant to the evaporator.

[0097] Example 7. The dryer system according to examples 5 or 6, dependent on example 4, wherein the liquid desiccant container is arranged to receive the regenerated liquid desiccant from the evaporator and to feed the liquid desiccant to the absorbing device.

[0098] Example 8. The dryer system according to any one of examples 4 to 7, wherein the dryer system is configured to provide the regenerated liquid desiccant to the liquid desiccant container.

[0099] Example 9. The dryer system according to any one of examples 1 to 8, wherein the condenser is configured to produce liquid water, and configured to dilute the liquid desiccant entering the evaporator with the produced liquid water.

[0100] Example 10. The dryer system according to any one of examples 1 to 9, comprising a second absorbing device arranged to absorb moisture from the input air for the dryer before the input air for the dryer is input to the heat exchanger and using a liquid desiccant such that the input air for the dryer is pre-heated.

[0101] Example 11 . The dryer system according to any one of examples 1 to 10, wherein the liquid desiccant is a salt-based aqueous solution, wherein optionally the salt-based aqueous solution is selected from the group consisting of potassium acetate-based solution, calcium chloride-based solution, sodium sulfate-based solution, lithium bromide-based solution, potassium carbonate-based solution, sodium chloride-based solution, potassium chloride-based solution, magnesium chloride-based solution, calcium chloride-based solution, ammonium chloride-based solution, zinc chloridebased solution, lithium chloride-based solution, and iron chloride-based solution.

[0102] Example 12. The dryer system according to any one of examples 1 to 11 , wherein the absorbing device is a spray tower absorber, a falling film absorber, or a plate heat exchanger absorber.

[0103] Example 13. The dryer system according to any one of examples 1 to 12, wherein the heater is an electric heater, a gas heater, a natural gas heater, a methane gas heater, or a biomass heater.

[0104] Example 14. The dryer system according to any one of examples 1 to 13, wherein the dryer is configured to dry food stuffs using the heated input air.

[0105] Example 15. The dryer system according to any one of examples 1 to 14, wherein the dryer is a kiln dryer, a conveyor dryer, a rotary dryer, a belt dryer, a spray dryer, or a flash dryer.

[0106] Example 16. The dryer system according to any one of examples 1 to 15, wherein the heat exchanger comprises an air-to-liquid heat exchanger and a liquid-to-air heat exchanger, wherein the air-to-liquid heat exchanger is configured to transfer heat from the heated output air to a heat transfer liquid, wherein the liquid-to-air heat exchanger is configured to transfer heat from the heat transfer liquid to the input air for the dryer.

[0107] Example 17. The dryer system according to example 16, wherein the heat exchanger further comprises a liquid-to-liquid heat exchanger configured to transfer heat from the condensed water to the heat transfer liquid coming from the air-to-liquid heat exchanger.

[0108] Example 18. A heat recovery system for heating input air for a dryer, the system comprising: an absorbing device configured to absorb moisture from output air of the dryer using a liquid desiccant such that heated output air is produced; an evaporator in fluid communication with the absorbing device and configured to evaporate water from the liquid desiccant; a condenser configured to condense the evaporated water and exchange heat with input air for the dryer, and a heat exchanger arranged to transfer heat from the heated output air to the input air for the dryer, wherein the condenser is configured to produce liquid water, and the heat recovery system is configured to dilute the liquid desiccant entering the evaporator with the produced liquid water.

[0109] Example 19. The heat recovery system according to example 18, further comprising a liquid desiccant container arranged in fluid communication with the absorbing device and the evaporator.

[0110] Example 20. The heat recovery system according to examples 18 or 19, wherein the liquid desiccant container is arranged to receive the used liquid desiccant from the absorbing device and feed the liquid desiccant to the evaporator.

[0111] Example 21. The heat recovery system according to examples 18 to 20, wherein the liquid desiccant container is arranged to receive the regenerated liquid desiccant from the evaporator and feed the liquid desiccant to the absorbing device.

[0112] Example 22. A method for a dryer system, the method comprising: absorbing moisture from output air of a dryer using a liquid desiccant in an absorbing device to produce heated output air; evaporating water from the used liquid desiccant in an evaporator; condensing the evaporated water in a condenser and exchanging heat with input air for the dryer; transferring heat from the heated output air to the input air for the dryer in a heat exchanger.

[0113] Example 23. The method according to example 22, comprising diluting the liquid desiccant entering the evaporator with liquid water produced by the condenser. Example 24. The method according to examples 22 or 23, further comprising providing additional heating to the input air for the dryer using a heater.

[0114] Example 25. The method according to example 22, 23, or 24, further comprising receiving the used liquid desiccant from the absorbing device in a liquid desiccant container and feeding the liquid desiccant from the liquid desiccant container to the evaporator.

[0115] Example 26. The method according to any one of examples 22 to 25, further comprising receiving regenerated liquid desiccant from the evaporator in the liquid desiccant container and feeding the liquid desiccant to the absorbing device.

[0116] Example 27. The method according to any one of examples 22 to 26, further comprising pumping the regenerated liquid desiccant to the liquid desiccant container.

[0117] The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms “comprises,” “comprising,” “includes,” and / or “including” when used herein specify the presence of stated features, integers, actions, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, actions, steps, operations, elements, components, and / or groups thereof.

[0118] It will be understood that, although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the present disclosure.

[0119] It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present.

[0120] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0121] It is to be understood that the present disclosure is not limited to the aspects described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the present disclosure and appended claims. In the drawings and specification, there have been disclosed aspects for purposes of illustration only and not for purposes of limitation, the scope of the disclosure being set forth in the following claims.

Claims

Claims1. A dryer system (10, 200, 500, 600) comprising: a dryer (12) configured to dry a material using heated input air, an absorbing device (24) arranged to absorb moisture from output air of the dryer (12) using a liquid desiccant such that heated output air is produced, an evaporator (28) arranged in fluid communication with the absorbing device (24) and configured to evaporate water from the used liquid desiccant, a condenser (32) arranged to condense the evaporated water and exchanging heat with input air for the dryer, and a heat exchanger (50) arranged to transfer heat from the heated output air to the input air for the dryer (12).

2. The dryer system (10, 200, 500, 600) according to claim 1 , comprising a heat recovery system (20) including the absorbing device (24), the evaporator (28), the condenser (32) and the heat exchanger (50).

3. The dryer system (10, 200, 500, 600) according to claim 2, comprising a heater (60) for providing additional heating to the input air received from the heat recovery system (20).

4. The dyer system (10, 200, 500, 600) according to claims 1 , 2 or 3, wherein the evaporator (28) is configured to evaporate the water from the used liquid desiccant such that regenerated liquid desiccant is produced.

5. The dryer system (10, 200, 500, 600) according to claims 1 to 4, further comprising a liquid desiccant container (36) arranged in fluid communication with the absorbing device (24) and the evaporator (28).

6. The dryer system (10, 200, 500, 600) according to claim 5, the liquid desiccant container (36) is arranged to receive the used liquid desiccant from the absorbing device (24) and feed the liquid desiccant to the evaporator (28).

7. The dryer system (10, 200, 500, 600) according to claims 5 or 6, dependent on claim 4, wherein the liquid desiccant container (36) is arranged to receive the regenerated liquid desiccant from the evaporator (28) and to feed the liquid desiccant to the absorbing device (24).

8. The dryer system (10, 200, 500, 600) according to any one of claims 4 to 7, wherein the dryer system (10, 200, 500, 600) is configured to provide the regenerated liquid desiccant to the liquid desiccant container (36).

9. The dryer system (10, 200, 500, 600) according to any one of claims 1 to 8, wherein the condenser (32) is configured to produce liquid water, and wherein the system is configured to dilute the liquid desiccant entering the evaporator (28) with the produced liquid water.

10. The dryer system (10, 200, 500, 600) according to any one of claims 1 to 9, comprising a second absorbing device (90) arranged to absorb moisture from the input air for the dryer (12) before the input air for the dryer (12) is input to the heat exchanger (50) and using a liquid desiccant such that the input air for the dryer (12) is pre-heated.

11. The dryer system (10, 200, 500, 600) according to any one of claims 1 to 10, wherein the liquid desiccant is a salt-based aqueous solution, wherein optionally the salt-based aqueous solution is selected from the group consisting of potassium acetate-based solution, calcium chloride-based solution, sodium sulfate-based solution, lithium bromide-based solution, potassium carbonate-based solution, sodium chloride-based solution, potassium chloride-based solution, magnesium chloridebased solution, calcium chloride-based solution, ammonium chloride-based solution, zinc chloride-based solution, lithium chloride-based solution, and iron chloride-based solution.

12. The dryer system (10, 200, 500, 600) according to any one of claims 1 to 11 , wherein the absorbing device (24) is a spray tower absorber, a falling film absorber, or a plate heat exchanger absorber.

13. The dryer system (10, 200, 500, 600) according to claim 3 to 12, in dependence of claim 3, wherein the heater (60) is an electric heater, a gas heater, a natural gas heater, a methane gas heater, or a biomass heater.

14. The dryer system (10, 200, 500, 600) according to any one of claims 1 to 13, wherein the dryer (12) is configured to dry food stuffs using the heated input air.

15. The dryer system (10, 200, 500, 600) according to any one of claims 1 to 14, wherein the dryer (12) is a kiln dryer, a conveyor dryer, a rotary dryer, a belt dryer, a spray dryer, or a flash dryer.

16. The dryer system (10, 200, 500, 600) according to any one of claims 1 to 15, wherein the heat exchanger (50) comprises an air-to-liquid heat exchanger (52) and a liquid-to-air heat exchanger (54), wherein the air-to-liquid heat exchanger (52) is configured to transfer heat from the heated output air to a heat transfer liquid, wherein the liquid-to-air heat exchanger (54) is configured to transfer heat from the heat transfer liquid to the input air for the dryer.

17. The dryer system (10, 200, 500, 600) according to claim 16, wherein the heat exchanger (50) further comprises a liquid-to-liquid heat exchanger (56) configured to transfer heat from the condensed water to the heat transfer liquid coming from the air- to-liquid heat exchanger (52).

18. A heat recovery system (20) for heating input air for a dryer (12), the system comprising: an absorbing device (24) configured to absorb moisture from output air of the dryer (12) using a liquid desiccant such that heated output air is produced; an evaporator (28) in fluid communication with the absorbing device (24) and configured to evaporate water from the liquid desiccant; a condenser (32) configured to condense the evaporated water and exchange heat with input air for the dryer (12), and a heat exchanger arranged to transfer heat from the heated output air to the input air for the dryer (12),wherein the condenser (32) is configured to produce liquid water, and the heat recovery system (20) is configured to dilute the liquid desiccant entering the evaporator (28) with the produced liquid water.

19. The heat recovery system (20) according to claim 18, further comprising a liquid desiccant container (36) arranged in fluid communication with the absorbing device (24) and the evaporator (28).

20. The heat recovery system (20) according to claims 18 or 19, wherein the liquid desiccant container (36) is arranged to receive the used liquid desiccant from the absorbing device (24) and feed the liquid desiccant to the evaporator (28).

21. The heat recovery system (20) according to claims 18 to 20, wherein the liquid desiccant container (36) is arranged to receive the regenerated liquid desiccant from the evaporator (28) and feed the liquid desiccant to the absorbing device (24).

22. A method for a dryer system (10), the method comprising: absorbing moisture from output air of a dryer (12) using a liquid desiccant in an absorbing device (24) to produce heated output air; evaporating water from the used liquid desiccant in an evaporator (28); condensing the evaporated water in a condenser (32) and exchanging heat with input air for the dryer (12); transferring heat from the heated output air to the input air for the dryer (12) in a heat exchanger (50).

23. The method according to claim 22, comprising diluting the liquid desiccant entering the evaporator (28) with liquid water produced by the condenser (32).

24. The method according to claims 22 or 23, further comprising providing additional heating to the input air for the dryer (12) using a heater (60).

25. The method according to claim 22, 23, or 24, further comprising receiving the used liquid desiccant from the absorbing device (24) in a liquid desiccant container (36) andfeeding the liquid desiccant from the liquid desiccant container (36) to the evaporator (28).

26. The method according to claim 25, further comprising receiving regenerated liquid desiccant from the evaporator (28) in the liquid desiccant container (36) and feeding the liquid desiccant to the absorbing device (24).

27. The method according to claim 26, further comprising pumping the regenerated liquid desiccant to the liquid desiccant container (36).

Images