Method for the recovery of waste heat from heated launderette machines

A method for the effective recovery of as large a portion as possible of the energy in the waste heat of a trough mangle (10) or other launderette machines. To this end, provision is made for a portion of the energy contained in the waste heat to be recovered by cooling the waste heat in a heat exchanger (14), with the waste heat being cooled to such an extent that it falls below the dew point and condenses, with the result that the energy released during condensation and at least a large portion of the energy from the condensate can also be recovered. In this way, it is possible for up to half the residual energy in the moist waste air from a trough mangle (10) and the waste gas from a heating device to be recovered and reused again.

STATEMENT OF RELATED APPLICATIONS

This application is the U.S. National Phase Under Chapter II of the Patent Cooperation Treaty (PCT) of PCT International Application No. PCT/EP2008/000891 having an International Filing Date of 6 Feb. 2008, which claims priority on German Patent Application Nos. 10 2007 013 717.8 having a filing date of 19 Mar. 2007 and 10 2007 043 212.9 having a filing date of 11 Sep. 2007.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention relates to a method for the recovery of waste heat from heated launderette machines, in particular mangles, dryers and finishers.

2. Related Art

In commercial launderettes, considerable amounts of energy, specifically primarily thermal energy, are sometimes required to operate the launderette machines. This applies primarily to mangles, dryers and finishers. This energy is not carried out of the launderette by the washed laundry because the laundry leaves the launderette at the same temperature at which it was delivered as dirty laundry.

To date, it has been customary to route all the waste heat produced or discharged during operation of launderette machines to the outside. In this context, “waste heat” is to be understood as moist waste air from launderette machines and waste gases from heating devices for generating, for example, steam and heated oil for operating the launderette machines. Since energy costs are constantly increasing, the economic viability of a commercial launderette is considerably impaired when the waste heat is routed to the outside without being used.

BRIEF SUMMARY OF THE INVENTION

Taking the above as a starting point, the invention is based on the object of specifying a method for the recovery of thermal energy, in particular moist waste air, which is discharged by launderette machines, in particular mangles, dryers, finishers or the like, as a result of which it is possible to reduce the energy requirement of a commercial launderette.

A method for achieving this object is a method for the recovery of waste heat from heated launderette machines, in particular trough mangles, dryers and/or finishers, characterized in that the condensation energy and/or the energy in the condensate of the waste heat is at least partially recovered. Provision is made to also recover such energy from the waste heat (moist waste air and/or waste gas) which is contained in the condensate of the waste heat and/or is produced when the waste heat condenses. The condensation energy and the energy in the condensate make up a large portion of the energy from the waste heat, with the result that a large portion of the energy can be drawn by recovering at least some of this energy from the waste heat before the waste heat is routed to the outside. As a result, a large portion of the energy which is produced during operation of heated launderette machines can be reused.

According to a preferred development of the method, provision is made for the waste heat to be cooled to such an extent that it condenses and the energy which is produced in the process and also the energy in the condensate of the cooled waste heat are at least partially recovered. Therefore, the energy from the waste heat is then recovered until said waste heat condenses. However, not only the condensation energy, but preferably also the energy from the condensate, which forms when the waste heat is cooled further, is at least largely recovered according to the invention.

A further preferred refinement of the method makes provision for the waste heat to be cooled to below the dew point and the energy which is produced in the process to be at least partially, preferably largely, recovered. It is therefore possible to reuse not only the energy from the waste heat, preferably the energy in the moist waste air from launderette machines and in the waste gas from heating devices, until the dew point is reached, the said energy including the condensation energy, but also more energy in the waste heat, specifically such energy which is contained in the waste heat even after it has fallen below the dew point and/or is produced when the waste heat falls below the dew point. The more energy is recovered from the waste heat below the dew point, the greater is the degree of efficiency of energy recovery. A large portion of the energy supplied to the respective launderette machine, specifically almost all the energy with the exception of the radiated heat, can be recovered by using the energy in the waste heat below the dew point too.

Provision is also made for the energy from the waste heat to be recovered by at least one heat exchanger. This energy is energy which is produced when the waste heat is cooled, in particular also the condensation energy, and also the energy which is produced when the moist waste air is cooled to below the dew point. Heat exchangers are particularly suitable for drawing a large portion of the energy contained in waste heat, specifically also from the condensate which is in the liquid state, but still warm enough, which is produced when the waste heat is cooled to below the dew point.

It is feasible to recover all the waste heat using just one single heat exchanger. In this case, both moist waste air from the respective launderette machine and also the waste gas from a heating device for supplying the required energy to the launderette machine is fed to this heat exchanger. However, it is particularly advantageous for both the heating device and the launderette machine to at least each have their own associated heat exchanger. In this case, both the energy from the launderette machine and from the heating device can be recovered by the respective heat exchanger in a controlled manner. In this case, the heat exchangers may be different since they are matched firstly to the different energy contents of the moist waste air from the launderette machine and secondly to the waste gas from the heating device, in particular with regard to the heat-exchange performance.

If each launderette machine has its own associated heating device, this launderette machine has at least one associated heat exchanger which recovers the energy in the waste gas from the heating device of the launderette machine and possibly also the energy from the moist waste air from the launderette machine. However, it is also feasible to provide a central heating device in the launderette, the said central heating device centrally supplying the required energy to all or a plurality of the launderette machines. In this case, this central heating device has at least one associated heat exchanger. This central heat exchanger preferably serves only to recover the residual energy from the waste gas from the central heating device, whereas either each launderette machine has its own associated heat exchanger or the moist waste air from the launderette machines is conducted to a central heat exchanger for the purpose of recovering the moist waste air from the launderette machines. The said central heat exchanger may also be the heat exchanger of the central heating device. This single central heat exchanger then has to be correspondingly dimensioned.

The energy drawn from the waste heat, that is to say the moist waste air from the launderette machine or the waste gas from the heating device, by at least one heat exchanger is used to increase the temperature of a liquid, in particular a heat exchanger liquid. The heat exchanger liquid heated in this way, it being possible for the said heat exchanger liquid to be fresh water in the simplest case, can be used for an extremely wide variety of purposes, in particular within the launderette, for example in order to heat up the fresh water which is required for washing machines, but also for heating purposes. Therefore, it is also possible to use the recovered energy in the form of the hot water for external heating purposes, for example for remote heating purposes.

It is also feasible to use a heat exchanger liquid which has a boiling point which is above 100° C., that is to say is higher than the boiling point of water. The heat content of the heat exchanger liquid can be increased as a result. A relatively small quantity of heat exchanger liquid can then absorb a large amount of energy.

Provision is preferably made for the energy obtained when the waste heat is recovered from at least one launderette machine, in particular thermal energy, to be used to operate a different launderette machine which likewise requires thermal energy. In this way, the obtained energy remains within the launderette.

However, according to another preferred refinement of the method, it is also feasible to reuse the energy, which is obtained when the waste heat from a launderette machine is recovered, during operation of the same launderette machine. This therefore produces an energy circuit in the relevant launderette machine, with the result that only relatively little new energy has to be fed to the said launderette machine, specifically only energy which cannot be recovered, for example radiation energy and residual energy in the moist waste air and/or in the waste gas which does not allow economic recovery.

Provision is further made for the waste heat used to be moist waste air from a mangle, a dryer and/or a finisher. These launderette machines are usually operated using hot steam, hot air or heated oil as the heat carrier medium which still contains a large amount of energy when it leaves the launderette machine in the form of moist waste heat. Condensate which forms when the waste heat is cooled to below the dew point primarily still contains a considerable amount of energy which is recovered according to the invention, specifically preferably including the condensation energy.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The exemplary embodiments shown in the figures explain the invention in connection with a trough mangle10for commercial launderettes. The trough mangle10(shown only schematically in the figures) has a frame11with a mangle trough and a mangle roller which can be driven in rotation. However, the trough mangle10may also have a plurality of mangle rollers and mangle troughs.

The stationary mangle trough surrounds approximately the lower half of the periphery of the mangle roller. The mangle trough can be heated. To this end, flow channels for a heat carrier medium are arranged within the mangle trough. For example, the mangle troughs may be designed in the manner of cushion plates. A mangle trough of this type is formed from two approximately semicircular overlapping metal sheets which are tightly welded all around and are additionally connected to one another in the region of the surface by a grid of weld spots. Between the weld spots, the metal sheets are spaced apart from one another in order to form the flow channels for the heat carrier medium flowing through the mangle trough.

The trough mangle10shown inFIG. 1is heated by steam. That is to say, in this trough mangle10, steam, in particular hot steam, is conducted through the flow channels in the mangle trough. In the exemplary embodiment shown here, the steam is generated centrally in the launderette and routed through the mangle trough of the trough mangle10.

The steam-heated mangle trough heats the still damp laundry which is located between the mangle trough and the mangle roller during the mangling process. The laundry is moved along the mangle trough by the rotating mangle roller. In the process, the residual moisture of the laundry evaporates. This residual moisture is bound in the hot air generated by the heated mangle trough, as a result of which moist waste air is produced. This waste air is discharged through the mangle roller by the moist waste air being sucked into the mangle roller and discharged from the mangle roller.

The trough mangle10has an associated heat exchanger14. In this case, said heat exchanger may, in principle, take all conceivable forms of heat exchangers14. In the exemplary embodiment shown, the heat exchanger14is in the form of a horizontally running plate heat exchanger. The said plate heat exchanger has a plurality of heat exchanger plates13which are situated at a distance next to one another and have rectangular surface areas. The long longitudinal edges of the heat exchanger plates13run horizontally; the shorter transverse edges, in contrast, run vertically. The heat exchanger plates13, like the mantle trough, may be in the form of cushion plates with internal flow channels. The plurality of heat exchanger plates13which are situated at a distance and parallel next to one another are arranged in a sealed housing15.

The heat exchanger14is connected to the trough mangle10by a waste-air channel16. From one end of the mangle roller, the moist waste air collected therein is conducted to one end of the heat exchanger14through the waste-air channel16. For this purpose, the waste-air channel16issues into the end of the housing15of the heat exchanger14. The moist waste air arriving from the mangle roller flows past the outside of the heat exchanger plates13, that is to say through flow paths between adjacent heat exchanger plates13. In the process, the liquid, specifically heat exchanger liquid, which is conducted through the heat exchanger plates13of the heat exchanger14is heated by the residual energy from the moist waste air from the trough mangle10. The liquid is water, for example. However, it is also feasible to use a high-boiling heat exchanger liquid which has a higher boiling point than water. The moist waste air which is cooled and condensed as it flows along the outside of the heat exchanger plates leaves the housing15of the heat exchanger14through an outlet nozzle17which is arranged in that end region of the heat exchanger14which is opposite the waste-air channel16. Furthermore, the heat exchanger14has a condensate connection18at the rear lower end of the housing14. Liquid condensate which is produced when the moist waste air from the mangle roller is cooled can be discharged via the said condensate connection, with, according to the invention, a large portion of the thermal energy contained in the condensate having been drawn from the condensate and thus recovered beforehand.

The housing15of the heat exchanger14has, in a rear lower end region, a feed connection23for cold heat exchanger liquid, specifically water in the simplest case. This water or another heat exchanger liquid serves to feed the secondary circuit of the heat exchanger14. Heat exchanger liquid which is heated by the heat exchanger plates13of the heat exchanger14is routed out of the heat exchanger14via a discharge connection24in the front upper end region of the housing15.

The method according to the invention is distinguished in that the moist waste air from the mangle roller, said waste air being vapours or steam, but also the energy produced when the moist waste air condenses and/or the energy contained in the condensate are/is reused. That is to say, the moist waste air from the mangle roller is cooled in the heat exchanger14to such an extent that it condenses, with not only the energy which is produced in the process being recovered, but also the energy which is produced when the condensate is cooled further in the region of the heat exchanger14. Therefore, the moist waste air from the trough mangle10is cooled to below the dew point. As a result, a large portion of the energy supplied to the trough mangle10can be recovered again and reused.

Since the heat recovery in the heat exchanger14is performed by cooling the moist waste air from the mangle roller to below the dew point, and in the process the energy from the condensing waste air and/or from the condensate is recovered, at least 50% of the energy fed to the trough mangle10can be recovered and reused.

The recovered energy serves to heat liquid, in particular water, which is conducted through the heat exchanger14, specifically its secondary circuit. The heated water can be used within the launderette, specifically in areas where warm water, for example warm fresh water, is required. However, the obtained energy can also be used for entirely different purposes, for example heating purposes. It is also feasible to route the heated liquid, in particular when it is a high-boiling heat exchanger liquid and not water, through a further heat exchanger in order, for example, to heat fresh water for washing machines.

The trough mangle10shown inFIG. 1is supplied with steam or another form of thermal energy, for example heated oil, by a central heating device. The central heating device may likewise have an associated heat exchanger which draws at least a portion, preferably a large portion, of the energy from the waste gas, for example, from a burner of the central heating device, before the waste gas is routed to the outside through the flue. According to the invention, the waste gas is also cooled here until it condenses. As a result, the condensation energy which is produced during the condensation process can be at least partially recovered, as can, preferably additionally, also at least a portion of the energy still contained in the condensate.

FIG. 2shows the trough mangle10in which the medium for heating the mangle trough is heated by an integrated heating device19which is associated with the trough mangle10. In the exemplary embodiment shown, the trough mangle is a trough mangle10with an oil-heated mangle trough. The oil is heat carrier oil which is heated in a heat exchanger21which is fired by a burner20. The oil heated in this way is then routed through the mangle trough of the trough mangle10and as a result the trough mangle10is heated.

In the case of this oil-heated trough mangle10too, moist waste air accumulates in the mangle roller, said waste air, as in the exemplary embodiment according toFIG. 1, being recovered by the heat exchanger14which is associated with the trough mangle10.

The burner20for heating oil for heating the mangle trough generates waste gas, from which the residual energy is likewise partially recovered. To this end, provision is made, in the exemplary embodiment according toFIG. 2, to provide a second heat exchanger22which serves to recover heat. The heating device19is associated with this second heat exchanger22, so that it recovers only the residual energy from the waste air from the burner20. In this case, the waste gas is also preferably cooled to below the dew point. In the process, condensate is produced, even when thermal energy which is contained in the waste gas is recovered. The condensation energy which is produced in the process and the energy in the condensate are at least partially recovered, so that they can be reused, preferably in the launderette, and primarily for the operation of launderette machines which require thermal energy. The heat exchanger may be constructed exactly like the heat exchanger14for the purpose of recovering the moist waste air from the mangle roller, that is to say as a plate heat exchanger with heat exchanger plates13formed from cushion plates. It is also feasible to form the heat exchanger22in another way which is conventional for heat exchangers. The upright heat exchanger22for the waste gas from the heating device19has a feed connection23, which, at its lower end region, issues into the housing15, for a heat exchanger medium, for example water. The heated water or another heat exchanger medium of the secondary circuit leaves the housing15of the heat exchanger22in the upper end region of the said housing through a discharge connection24.

A portion of the residual energy from the waste gas of the burner20for heating the mangle trough can also be recovered by the heat exchanger22. It is irrelevant here whether the burner20is gas- or oil-heated.

The cooled waste gas from the burner20exits the upper end of the preferably upright elongate heat exchanger22to the outside, specifically preferably via a flue which is not shown inFIG. 2. The waste air which is cooled in the heat exchanger14may also possibly be routed from the trough mangle10to the outside via the same flue.

FIG. 3shows a further exemplary embodiment of the invention, which differs from the exemplary embodiment ofFIG. 2in that only a single heat exchanger25is provided for recovering the residual energy from the moist waste air from the trough mangle10and the waste gas from the heating device19of the trough mangle10. A waste-air conduit26of the trough mangle10and a waste-gas conduit27of the heating device19for providing the energy required for the trough mangle10, for example steam or heated oil, are combined to form a common header conduit28which is guided to one end of the heat exchanger25which is arranged horizontally (lying flat) in the exemplary embodiment shown. In any case, the heat exchanger25is, in principle, constructed exactly like the heat exchanger14. Accordingly, identical reference numerals are used for identical parts and reference is made to the description of the heat exchanger14in conjunction with the exemplary embodiment ofFIG. 1.

The preferred exemplary embodiment of the invention, which is described below in conjunction with a trough mangle10, can also be used in other launderette machines which have a high energy requirement, for example dryers and finishers. In this case too, so much energy is drawn from the waste heat, at least the moist waste air and/or vapours by cooling that the waste heat falls below the dew point and the moisture in the waste air condenses, with the condensation energy and the energy from the condensate being at least largely recovered according to the invention, just like the remaining energy from the moist waste air which is produced when the said moist waste air is cooled to the dew point. Similarly, in the case of other launderette machines, a portion, preferably a large portion, of the residual energy can be drawn from the waste gas from a heating device and reused.

List of Reference Symbols