DRYERS FOR DRYING DRY GOODS, ESPECIALLY TEXTILES

Description

[0001] The invention relates to a dryer for drying dry goods, in particular textiles, a heating chamber and a cooling chamber which are designed to be gas-tight against one another and / or against the outside environment, a connecting line which connects the chambers to one another in a fluid-conducting manner and has a closing valve, a vacuum pump which can be operatively connected to at least one of the two chambers, a heat pump which can be operatively connected to the two chambers, wherein the heat pump comprises a condenser and an evaporator.

[0002] Furthermore, the invention relates to a method for drying dry goods, in particular textiles, which is carried out using such a dryer.

[0003] In known drying processes, particularly textile drying processes, the material to be dried is dried by evaporating the liquid phase, particularly by evaporating water. Evaporation occurs when the temperature-dependent saturation vapor pressure is greater than the prevailing partial pressure of the substance evaporated into the ambient atmosphere. The evaporation process is maintained by constantly exchanging the saturated atmosphere. Evaporation is promoted by the addition of heat energy. The pressure of the ambient atmosphere can also be lowered to support this process, thus requiring less heat energy to be added.

[0004] DE 36 41 665 A1 discloses an energy-saving vacuum drying process and a device for drying textiles. In this process, the textiles to be dried are heated using the condenser of a heat pump, and the water vapor condenses on the evaporator of the heat pump. Both the evaporator and the condenser are located within a vacuum chamber, which also contains the laundry container. The boiling point is lowered by creating a negative pressure in the vacuum chamber. A disadvantage of this process is that both the evaporation and the subsequent condensation of the moisture take place in the same vacuum container. Therefore, a correspondingly large container must be used to prevent the dried goods from coming into contact with the condensate. Second, a larger cold reservoir must be provided to prevent the condensate from evaporating again until the end of the drying process.Alternatively, the condensate can be pumped out at increased energy expenditure.

[0005] A vacuum drying device is known from DE 20 2009 013 968 U1. The material to be dried is placed on drying material supports in the vacuum drying device. The drying material supports are connected to Peltier elements. The drying process is monitored by temperature and pressure sensors. A disadvantage of the disclosed vacuum drying device is that the moist air must be pumped out with a vacuum pump during the entire drying process, which requires increased energy consumption.

[0006] EP 0 505 677 A1 discloses a multi-chamber vacuum belt dryer in which different pressure conditions are created in several drying chambers. This solves the problem of limiting the final product moisture content by the moisture initially introduced. However, the increased energy consumption for operating the vacuum pumps remains a disadvantage.

[0007] The publication DE 10 2012 107 368 B4 describes a dryer of this type, intended especially for drying textiles. The dryer and the method for operating the dryer are advantageous and also lead to satisfactory results. Nevertheless, the energy consumption is relatively high and the drying process takes a relatively long time.

[0008] The document JP 2005 241239 A discloses a dryer according to the prior art.

[0009] The invention is based on the object of providing a dryer and a method for operating such a dryer for drying goods to be dried, in particular textiles, which do not have the disadvantages of the prior art. In particular, the dryer and the method should be as energy-efficient as possible. The goods to be dried should be dried as gently as possible.

[0010] The invention solves this problem by a dryer having the features of claim 1 and by a method applicable to this dryer having the features of the independent method claim.

[0011] The dryer according to the invention therefore comprises, in addition to the heating and cooling chambers, the vacuum pump, and the heat pump, a steam generator that feeds the generated steam into the heating chamber via a steam line. The steam supplied by the steam generator removes moisture from the material being dried in the heating chamber, thereby drying the material. The resulting moist steam is then fed to the cooling chamber via the connecting line.

[0012] The dryer according to the invention is particularly suitable for drying textiles, but is also suitable for efficient and rapid drying of, for example, technical components or any other objects or materials.

[0013] By using the steam as an energy source and the pressure differences in the various chambers, highly efficient drying can be achieved. Especially when the system is essentially air-free, the energy transfer between steam and the moisture stored in the drying material is direct and therefore much faster. Dryer steam is a much more efficient energy source because its heat capacity is significantly higher than that of dry air at the same temperature.

[0014] The heating chamber and the cooling chamber are connected to each other via at least one connecting line in which a shut-off valve is located. The term shut-off valve is used as a synonym for all suitable switching devices, especially valves.

[0015] The material to be dried can be stored in the heating chamber. The evaporated moisture condenses in the cooling chamber. Furthermore, the dryer according to the invention comprises at least one vacuum pump operatively connected to at least the cooling chamber. Evaporation of moisture in the heating chamber creates overpressure, and condensation of the moisture in the cooling chamber creates negative pressure, creating a pressure difference between the heating chamber and the cooling chamber. The vacuum pump is designed to pump dry air out of the cooling chamber as needed.

[0016] The heat pump is connected to the cold chamber. When the heat pump is operated, the heat energy extracted from the cold chamber is ultimately transferred to the heating chamber and the material being dried, which starts the evaporation of the moisture. As the moisture heats up and evaporates, the pressure inside the heating chamber increases. At the same time, the cooling of the air in this area causes the moisture present in the cold chamber to condense, while its volume simultaneously reduces, and the pressure is reduced. This creates a pressure difference between the cold chamber and the heating chamber. To support this, the vacuum pump can be used to create a negative pressure in the cold chamber right at the start of the drying process by pumping out the air in the cold chamber.At a predetermined pressure difference or after a predetermined drying time, the shut-off valve in the connecting line connecting the heating chamber and the cooling chamber opens. Air with a high moisture content flows from the heating chamber into the cooling chamber.

[0017] In the cold chamber, the moisture begins to condense, so that as condensation continues, dry, cool air remains in the cold chamber at a negative pressure. If necessary, this air can be pumped out into the environment using the vacuum pump without concern for moisture damage, ensuring that the desired negative pressure in the cold chamber is regulated to a desired optimal value. As the water vapor condenses, its volume shrinks by a factor of approximately 800, which leads to a renewed negative pressure in the cold chamber. In the heat chamber, vapor formation and a simultaneous increase in pressure continue as long as moisture remains in the dry goods.After the drying process is complete, the vacuum pump operates so that there is essentially no air left in the cold and heat chambers, so that after complete evaporation and condensation of the moisture, a constant pressure in the cold and heat chambers indicates the end of the drying process. The drying process is therefore complete when both chambers, the heat chamber containing the dry goods and the cold chamber, have the same desired negative pressure.

[0018] The steam generator produces relatively dry steam, which is introduced into the heating chamber via a steam line. The steam generator uses liquid supplied by the heat pump, preferably water. For this purpose, the invention provides a hot water tank into which warm water from the heat pump is fed, which is used by the steam generator to produce the relatively dry steam.

[0019] According to the invention, the heat pump is connected to the hot water tank via a heat pipe and to the cold chamber via a cooling pipe. If the heat pump is designed with a heat or cooling pipe, these comprise a heat transfer medium or a coolant, respectively. The steam generator is thus fed with preheated water. Preferably, a partial flow of the hot water from the heat pump can also be used directly to heat the heating chamber.

[0020] According to the invention, the heat conduction can run in sections through the housing or the housing wall of the heat chamber, so that it heats the heat chamber before the water heated by the heat pump reaches the hot water tank.

[0021] The hot water tank can be used as energy storage for the next drying cycle. Since the heat pump generates temperatures up to approximately 90°C, the water stored in the hot water tank also has a temperature of nearly 90°C.

[0022] In a particularly advantageous design variant, the condensate accumulating in the cold chamber is also pumped into the hot water tank via a water pump.

[0023] It has also proven beneficial to heat or preheat the heating chamber independently of the steam supplied by an additional heater, such as an electric heater, to prevent condensation on the interior walls of the heating chamber. The electric heater is preferably located in the housing of the heating chamber, particularly below the dry goods.

[0024] The heat energy provided by the heat pump to heat the heat chamber is thus supplied by the condensation enthalpy with only minimal use of external energy sources.

[0025] Preferably, the described drying process can be carried out several times in succession. In particular, a predetermined number of drying processes can be carried out, or a predetermined drying time can define the number of drying processes to be carried out. In a particularly preferred embodiment, the drying time is less than half an hour. Particularly preferably, the drying process, which may be carried out several times, is terminated when, after essentially complete evaporation and subsequent condensation of the moisture from the material to be dried, an equal pressure has been established in the heating chamber and in the cooling chamber.

[0026] The greater the power of the heat pump and the area of ​​the associated heat exchanger, the faster the drying process.

[0027] In a preferred embodiment, the heating chamber comprises a device for storing the dry goods, in particular for stacking or hanging the dry goods. Preferably, the heating chamber comprises a shelving system or a hanging device, in particular pipes or rods.

[0028] Further preferably, the heat pump's heat pipe is arranged in sections within the heating chamber and designed as a shelf or hanging device. This allows, for example, laundry to be stored or hung without mechanical stress, allowing for crease-free drying. Furthermore, optimal heat transfer to the items being dried is ensured. Further preferably, the heat pump's evaporator or the cooling pipe within the cooling chamber is designed as cooling fins or cooling panels, on which the water vapor can effectively condense.

[0029] In a further preferred embodiment, at the beginning of the drying process, the pressure in the cold chamber can be reduced with the vacuum pump, in particular to below a pressure of 0.5 bar. Particularly preferably, the vacuum pump reduces the pressure in the cold chamber to a pressure of 0.3 bar.

[0030] In a further preferred embodiment of the dryer, it comprises two condensate containers for collecting the condensed water vapor, which are located at the bottom of the cold chamber or are connected to the cold chamber. When a maximum fill level is reached or after a specified period of time, at least one of the condensate containers is sealed gas-tight against the cold chamber and the air pressure in the at least one condensate container is adjusted to the ambient pressure. The condensate is then released into the hot water tank or a wastewater pipe by opening a valve on the condensate container. Particularly preferably, a negative pressure is then again established in the condensate container, which corresponds to the pressure in the cold chamber. By using the condensate containers, in particular alternately, it is achieved that the constant operation of a vacuum pump to remove the condensate is not required.At the same time, re-evaporation of the condensate is prevented.

[0031] In a preferred embodiment, at least one control valve, in particular at least one 3-way valve, is located between the condensate tanks and the cold chamber. Depending on the fill level of the condensate tanks, the control valve directs the condensate from the cold chamber into a first condensate tank, while the second condensate tank is sealed gas-tight from the cold chamber and the first condensate tank, and the condensate is drained away. Further preferably, the condensate tanks have at least one valve, in particular a pressure equalization valve, with which pressure equalization can be established between the condensate tanks and the outside environment.

[0032] In a further preferred embodiment, both chambers have sensors for pressure, temperature, and humidity, thereby enabling continuous monitoring of the drying process. Particularly preferably, the dryer has a control system that controls the drying process depending on the measured values ​​of pressure, temperature, or humidity. In particular, the control system can ensure that a minimum temperature, in particular a minimum temperature of 2 degrees Celsius, is not undercut in the cold chamber. Further preferably, the control system controls the pressure and temperature parameters, in particular the pressure and temperature in the cold chamber, so that re-evaporation of the moisture condensed in the cold chamber is prevented.

[0033] Preferably, the input parameters for the control system are supplied by the sensors for pressure and / or temperature and / or air humidity. Further preferably, by measuring a constant pressure in the heating chamber and in the cooling chamber, in particular by eliminating the pressure difference between the heating chamber and the cooling chamber, the control system can terminate the drying process, which may have been repeated several times. Further preferably, the control system allows the user extensive control over the drying process. In particular, the user can choose between operating modes with or without a pressure reduction in the cooling chamber at the beginning of the drying process. Further preferably, the user can select the desired residual moisture content in the material to be dried or the drying time.

[0034] The dryer preferably has thermal insulation between the chambers and the outside environment. Likewise preferably, the heating chamber has an opening that can be closed gas-tight via a closing element, in particular a door, for filling and emptying with dry goods, in particular laundry.

[0035] In a further preferred embodiment, the dryer has at least one air pressure equalization valve, which is arranged between at least one of the heating or cooling chambers and the outside environment. After the drying process is complete, pressure equalization between the outside environment and the heating or cooling chamber can be established by opening the air pressure equalization valve. After pressure equalization has been established in the heating chamber, a closing element, in particular a door, of the heating chamber can be opened, and the dried material can be removed.

[0036] In a particularly preferred embodiment, the dryer has a device for dissipating excess heat to the outside environment or to a heating system, with the heat preferably being transferred to the heating system via a heat exchanger. This ensures the operation of the heat pump, which is necessary for cooling the cold chamber, without placing excessive heat on the material being dried.

[0037] In a further preferred embodiment, the dryer has a control system which is designed in particular to control the steam generator, the heat and vacuum pump, the pressure equalization valves between the heating and / or cooling chamber and the outside environment, the pressure equalization valves between the condensate containers and the outside environment, the control valve between the condensate containers and the cooling chamber, and the switching means in the lines between the heating and cooling chamber.

[0038] In a preferred embodiment, the heating chamber comprises a rotating laundry drum or a rotating shelf. Further preferably, the heating chamber and the cooling chamber are arranged inside or next to each other, or the cooling chamber is arranged below the heating chamber. In particular, the cooling chamber has a smaller volume than the heating chamber.

[0039] In a further embodiment, the cold chamber is preferably designed in the form of a long tube or in the form of a long hose, in particular in the form of a spiral tube or a spiral hose, wherein the cold chamber, designed in particular as a spiral tube or as a spiral hose, is connected to the evaporator or to the cooling line of the heat pump comprising a coolant.

[0040] The vacuum pump pumps moist air from the heating chamber into the cooling chamber, which is typically designed as a spiral tube or hose. The water vapor contained in the warm air condenses and drains away. Advantageously, this design eliminates the need for a condensate tank, resulting in a very cost-effective design.

[0041] A further solution to the problem consists in providing a method for drying dry goods, in particular textiles, in particular with a dryer according to one of claims 1 to 3.

[0042] In the method according to the invention, the thermal enthalpy required to evaporate the moisture contained in the dry material is essentially supplied by a steam generator, wherein the heating chamber, which can in particular be sealed gas-tight, and the cooling chamber, which can in particular be sealed gas-tight, are connected by a connecting line and can be sealed gas-tight from one another. The method is energetically supported by a heat pump connected to a heating chamber and a cooling chamber. According to the method, the dry material to be dried is stored in the heating chamber. The evaporation of the moisture contained in the dry material then takes place in the heating chamber, and the condensation of the moist water vapor takes place in the cooling chamber.According to the process, an overpressure is generated by evaporation of the moisture in the heat chamber and a negative pressure is generated in the cold chamber by condensation of the moisture, such that a pressure difference is created between the heat chamber and the cold chamber.

[0043] By means of a vacuum pump connected to the cold chamber, the dry and cool air created by the continuous condensation of moisture in the cold chamber is pumped out of the cold chamber during the drying process without affecting the outside environment, thereby maintaining a pressure gradient between the cold chamber and the heat chamber.

[0044] By operating the heat pump and steam generator, the required energy consumption is minimized. Furthermore, the two-chamber system spatially separates the moisture and condensate from the dry goods, preventing the dry goods from becoming moist again.

[0045] Preferably, the heating chamber and the cooling chamber are sealed gas-tight from one another at the beginning of the drying process via the closing valve arranged in the connecting line. Particularly preferably, a vacuum is generated in the cooling chamber at the beginning of the drying process by means of the vacuum pump, in particular a vacuum of less than 0.5 bar, more particularly a vacuum of 0.3 bar.

[0046] Relatively dry steam is introduced from the steam generator into the heating chamber, while the connecting line between the heating chamber and the cooling chamber initially remains closed via the closing valve.

[0047] Further preferably, by operating the heat pump and the steam generator with the heating chambers and cooling chambers sealed off from one another in a gas-tight manner, the temperature in the heating chamber is increased and the temperature in the cooling chamber is reduced, whereby the increased temperature in the heating chamber causes the moisture in the dry material to be stored in the heating chamber to evaporate and the pressure in the heating chamber to rise. At the same time, the moisture in the air in the cooling chamber condenses. As a result of the condensation of the moisture in the cooling chamber and the reduction in temperature, the pressure in the cooling chamber drops, thus creating a pressure difference between the heating chamber and the cooling chamber. This phase lasts until a predetermined target pressure, for example between 1.0 and 1.5 bar, preferably between 1.1 and 1.2 bar, is reached in the heating chamber.

[0048] When a predetermined pressure difference or target pressure or a predetermined drying time is reached, the closing valve between the heating chamber and the cold chamber is opened, preferably slowly, thereby equalizing the pressure between the cold chamber and the heating chamber. This lowers the pressure in the heating chamber, allowing the moisture present in the drying material or in the room to continue evaporating at approximately 90°C. Furthermore, opening the closing valve allows air with a high moisture content to flow from the heating chamber into the cold chamber.

[0049] Moisture present in the air inside the cold chamber condenses on the cooling fins or cooling panels arranged within the cold chamber, leaving dry and cool air, especially in the cold chamber, as condensation continues. Condensation and the resulting reduction in moisture volume maintain a constant negative pressure in the cold chamber.

[0050] During the drying process, the vacuum pump extracts dry, cool air from the cold chamber, which particularly helps maintain the pressure difference between the cold chamber and the hot chamber. The drying process is preferably repeated several times. The drying process, which may be repeated several times, is preferably terminated when the pressure in the hot chamber and the cold chamber is identical.

[0051] In order to prevent ice formation in the cold chamber, which would be detrimental to the drying process, a minimum temperature, in particular a minimum temperature of 2°C, is not undercut in the cold chamber in a preferred embodiment of the drying process.

[0052] Further preferably, the condensate accumulated in the cold chamber during the drying process is drained away by means of two evacuable condensate containers connected to the cold chamber and sealed gas-tight against each other. Preferably, after the condensate has been drained, a negative pressure corresponding to the negative pressure prevailing in the cold chamber is created in the condensate containers.

[0053] By draining the condensate using the condensate tank, re-evaporation of the condensate is prevented and the energy-intensive operation of an additional pump to pump out the condensate is eliminated.

[0054] The condensate is preferably directed into a hot water tank, which also receives hot water generated by the heat pump. The water in the hot water tank is used by the hot water tank to generate steam.

[0055] In this process, excess heat energy generated by the heat pump that is not required for drying is dissipated to the outside environment or to a heating system via a specially designed device. This ensures continuous operation of the heat pump to lower the temperature in the cold chamber without placing excessive heat on the drying items, especially the textiles, in the heat chamber.

[0056] Further preferably, sensors are located in the heating chamber and in the cooling chamber to monitor the drying conditions, which, for example, measure the pressure or the temperature or the humidity in the chambers.

[0057] In a particularly preferred embodiment of the drying process, the drying process is controlled by a control system, with the control system receiving, for example, the pressure, temperature, or humidity within the heating chamber or the cooling chamber as input parameters. Furthermore, the desired residual moisture content or the total drying time can be set via the control system. The control system advantageously provides the user with complete control over the drying process.

[0058] The claimed drying method and the dryer according to the invention are described below using an exemplary embodiment. The single figure shows a simplified representation of a dryer according to the invention.

[0059] The figure shows a dryer 20 for drying dry goods, in particular textiles. A heating chamber 22 and a cooling chamber 24, which are designed to be gas-tight against each other and / or sealable against the outside environment, are arranged next to each other in the illustrated embodiment and are fluidly connected to each other via a connecting line 26. A closing valve 28 is arranged in the connecting line 26, via which the connecting line 26 can be closed.

[0060] In the illustrated embodiment, a vacuum pump 30 is connected to the cold chamber 24 via a vacuum line 32. The vacuum pump 30 also has an ambient line 34 through which air or excess pressure can be released to the environment.

[0061] A heat pump 36, which can be operatively connected to the two chambers 22; 24 and may, for example, comprise a condenser and an evaporator (not shown), is connected to the cold chamber 24 via a cooling line 38. Furthermore, the heat pump 36 is connected via a heat line 40 to a hot water tank 42, into which it introduces heated water.

[0062] A steam generator 44 is connected to the hot water tank 42 via an extraction line 46. Furthermore, the steam generator 44 is connected to the heating chamber 22 via a steam line 48. The steam generator 44 uses the water from the hot water tank 42 to generate steam, which is fed into the heating chamber 22 via the steam line 48 to dry the dry goods. Shut-off valves 28 are also arranged in the extraction line 46 and the steam line 48.

[0063] A water pump 50 is also provided between the cold chamber 24 and the hot water tank 42, via whose condensate lines 52 condensate from the cold chamber 24 can be introduced into the water tank 42.

[0064] The heating chamber 22 is equipped with a pressure sensor 54 and a thermometer 56.

Claims

1. A dryer (20) for drying dry goods (21), in particular textiles, with - a heating chamber (22), in which the dry good to be dried is to be arranged, and a cooling chamber (24), wherein the heating chamber (22) and the cooling chamber (24) are designed so that they can be sealed gastight against each other and / or against the outside environment, - a connecting line (26), which connects the chambers (22, 24) with each other in a fluid conducting manner, and has a closing valve (28), - a vacuum pump (30) effectively connected with the cooling chamber (24), - a heating pump (36) effectively connected with the two chambers (22; 24), wherein the heating pump (36) is connected with the cooling chamber (24) via a cooling line (38), and with a hot water tank (42) via a heating line (40), wherein the heat pump (36) introduces heated water into the hot water tank (42), - a steam generator (44), which directs generated steam into the heating chamber (22) via a steam line (48), wherein the steam generator (44) is connected with the hot water tank (42) via an extraction line (46), and uses the heated water from the hot water tank (42) to generate steam, wherein the steam supplied by the steam generator (44) is mixed with moisture of the dry good in the heating chamber (22), and the resulting moist steam can be fed to the cooling chamber (24) via the connecting line (26), wherein an overpressure can be generated by vaporizing the moisture in the heating chamber (22), wherein an underpressure can be generated by condensing the moisture in the cooling chamber (24), such that a pressure difference can be produced between the heating chamber (22) and cooling chamber (24), and wherein the vacuum pump (30) is designed for a demand-based pumping of dry air from the cooling chamber (24).

2. The dryer (20) for drying according to claim 1, characterized in that a condensate line is provided between the cooling chamber (24) and the hot water tank (42), through which the condensate from the cooling chamber (24) can be introduced into the hot water tank (42).

3. A method for drying dry goods with a dryer (20) according to one of claims 1 to 2, wherein - the dry good (22) to be dried is stored in the heating chamber (22), - the evaporation of the moisture in the good to be dried takes place in the heating chamber (22), - the condensation of the steam takes place in the cooling chamber (24), which is connected with the heating chamber (22) via a connecting line (26) and can be sealed in a gastight manner against the heating chamber (22), - an overpressure is generated by vaporizing the moisture in the heating chamber (22), - an underpressure is generated by condensing the moisture in the cooling chamber (24), such that a pressure difference is produced between the heating chamber (22) and cooling chamber (24), and - the dry and cool air produced by condensing the steam in the cooling chamber (22) is pumped out with a vacuum pump (26) connected with the cooling chamber (24), wherein the heat enthalpy necessary for evaporating the moisture in the dry good is supplied by a steam generator (44) and a heat pump (36) connected with a heating chamber (22) and a cooling chamber (24).

4. The method according to claim 3, characterized in that hot water generated by the heat pump (36) is directed into a hot water tank (42), wherein the steam generator (44) extracts the heated water from the hot water tank (42) via an extraction line (46), generates steam from it, which it introduces into the heating chamber (22) via a steam line (48).

5. The method according to claim 4, characterized in that condensate from the cooling chamber (22) can be introduced into the hot water tank (42) via a condensate line arranged between the cooling chamber (24) and the hot water tank (42).