CA1180910A - Apparatus for improving the coefficient of performance in an energy transfer system - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Novel apparatus is provided for improving the coefficient of performance in an energy transfer system. The apparatus includes a heat exchanger which has first inlet means for receiving a pressurized fluid being delivered thereto from a loop for conveying that fluid, and first outlet means for returning the fluid to that loop. A second inlet means is provided for receiving a second fluid from a second loop and a second outlet means is provided for returning the second fluid to that second loop. The heat exchanger includes the transfer means for transferring energy from the fluid in the first loop to the fluid in the second loop.
Third inlet means are provided for receiving a third fluid from a third loop, and a third outlet means is provided for returning the third fluid to the third loop. Means are provided which are responsive to the passage of the third fluid through the heat exchanger for subcooling the first fluid to remove useful heat therefrom before returning the first fluid to the first loop.

Description

~1~0~

The present invention relates to waste energy recovery systems and more particularly, systems e~lploying a working fluid for converting the waste energy developed for use in a manufacturing process~ and other~7ise vented to the atmosphere after being used, into usuable energy, preferably in the form of steam at a temperature and pressure not hereto-fore possible through the use of conventional techniques.
The application is a division of copending application Serial No. 394,476 filed January 19, 1982, Many large sca]e manufacturing faciiities generate extremely large quantities of waste energy, typically in the form of heat, during the performance of their manufacturing operations. This waste energy is completely lost after use and, in fact, is conventionally vented directly to the atmosphere. Attempts at energy recovery through ava la-ble techniques are either highly inefficient or so costly as to prohibi-tively exceed the savings which might result therefrom due to the energy recovered.
One of the best examples of the above situation exists in the pulp and paper industry in which huge equipment installations, which necessitate the use of extremely large amounts energy, are required to produce tons of pulp and paper on a daily basis. Equipment of this nature must also be capable of operating continuously and with veIy little down time. For example, such systems-as, for example thermo~
mechanical pulping (TMP) and chemimechanical pulping (CMP) systems re-quire extremely large quantities of electrical energy to operate motors having ratings in the thousands of horsepower range for the purpose of grinding wood chips to a fine pulp at an output rate of more than lOO
tons per day, for example. ~xtremely large quantities of waste energy are generated as a result of the conversion of the electrical power driving the motors, which electrical power is converted to mechanical wor~ and subsequently to thermal energy in the form of steam. 5team lS

passed through a tube containing the wood chips prior to their entry into a primary refiner t~ s~ften the chips and thereby facilitate the re-fining operation.
The chips are typically defibred between a pair of huge coun-ter-rotating aiScs. The heat generated auring the refining operation, which is performed in a confined region, is vented to the atmosphere through an exhaust conduit. Although some efforts have been developed to recycle small portions of the-vented steam to the aforementioned steaming tube in which the chips are initially heated and softened, the vast majority of the heat energy is unrecoverable and hence is lost.
It is therefore, an object of one aspect of the present inven-tion to provide novel method and apparatus for waste energy recovery to produce energy, either for reuse in the manufacturing facility producing the waste energy, or for use in other applications, or both.
An object of another aspèct of the present invention is to provide novel method and apparatus for recovery of waste energy in which the energy from the source producing the waste energy is transferred to an output working fluid through the advent of an intermediate working fluia.
An object of still another aspect of the present invention is to proviae a novel method and apparatus for recovery of waste energy obtained from thermomechanical pulping systems and the like and through the intermediary of a worXing fluia, which transfers the waste ener~r at high efficiency to an output worXing fluid.

An object of still another aspect of the present invention is to provide a novel method and apparatus for recovery of waste energy ob-tained from thermomechanical pulping systems and the like and through-the intermediary of a working fluid, which transfers the waste energy at high efficiency to an-output working fluid.
An object of still anoth.er aspect of the present invention is to provide a novel method and apparatus for recovery of waste energy from thermomechanical pulping systems and the like in which energy in the Eorm of heat is transferred to an output working fluid by way of an inter-mediate working fluid, the input energ~, intermediate working fluid and output working fluid being physically isolated from one another.
- An object of still another aspect of the present invention is to provide a novel method and apparatus for recovery of waste energy de-rived from two or more sources and utilizing intercooling tank mealls arranged between a pair of driven compressor means enabling the working fluid passing through said compressor means to be operated at significant-ly different temperature and pressure levels.
By one broad aspect of thi~. invention, apparatus is provided for improving the coefficient of performance in an energy transfer system, comprising: heat exchanger comprising first inlet means for receiving a pressurized fluid being delivered thereto from a loop for conveying the fluid, and first outlet means for returning the fluid to the loopi second inlet means for receiving a second fluid from a second loop and a second outlet means for returning the second fluid to the second loop; the heat exchanger including the transfer means for transferring energy from the fluid in the first loop to the fluid in the second loop; third inlet means for receiving a third fluid from a:third loop and third outlet means for returning the third fluid to the third loop; and means responsive to the o~

passage of the third fluid through the heat exchanger for subcooling the Eirst fluid to remove the useful energy therefrom before returning the first fluid to the first loop~
By a variant thereof, the first fluid is a refrigerant; the second fluid is a condensate capable of being converted to steam by the first fluid; and the third fluid comprises moist air.
By another aspect of this invention apparatus is provided for altering the transfer of energy in accordance with the energy changes in the input or out~put Eluid comprising; an array comprising a plurality of heat exchangersi a plurality of loops coupling each heat exchanger with next heat exchanger in the array; each heat e~changer having first fluid receiving means and second fluid receiving means for transferring energy from the fluid passing through the first fluid receiving means to the fluid passing through the second fluid receiving means; each of the loops being coupled to second fluid receiving means of each heat exchanger and the first fluid receiving means of the next adjacent heat exchanger in the array; each of the loops comprising means for increasing the energy stored in the fluid passing therethrough; selected ones of the heat exchangers further comprising third fluid receiving means for transferring energy from a fluid passing through the first fluid receiving means to a fluid passing through the fluid receiving means, means for selectively deactivating each loop to disconnect each heat exchanger from the next adjacent heat exchanger thereby reducing the number of heat exchangers actively operat~
ing in the array~
By another variant thereo~ each deactivating means comprises a valve which may be opened to couple its loop between adjacent heat ~ g ~. .

exchangers associated with the loop and closed to decouple the adjacent heat exchangers associated with the loop~
By another variant -thereof the apparatus further includes valve means for selectively coupling the third fluid receiving means to its associated fluid supply enabling at least a portion of the energy to be transferred to the fluid passing through the third fluid receiving means from fluid passing the first fluid receiving means and for decoupling the third fluid receiving means from its associated fluid source ~or enabling energy to be transferred from the fluid in the first fluid recovery means to the fluid in the second fluid recovery means~
By a variation thereof, each of the loops comprises valve means and means for increasing the energy stored in the fluid in the loop as it passes therethrough.
By another variation thereof, each of the loops comprises valve means and compressor means for increasing the energy stored in the fluid in the loop as it passes therethrough.
By yet another variation thereof, the energy stored in the fluid introduced into the third fluid receiving means is transferred to the fluid in the second fluid receiving means when the valve means are closed~

By yet another aspect of this invention, apparatus is provided for recovering waste energy comprising~ a first loop for receiving a first fluid vented from a utilization device delivered to the first conduit at an elevated temperature level; a second loop containing a second fluid;
a third loop containing a third flùid; the first/ second and third loops being indepenaent of one another7 first heat exchanger means having first fluid receiving means for receiving the first fluid from the first loop ~o~

and second fluid receiving means for receiving -the second fluid from the second loop; the second fluid receiving means comprising means for trans~
ferring energy from the first fluid in the first loop to the second fluid in the second loop; second heat exchanger means coupled to the first and third loops for transferring energy from the first fluid in the first loop as the fluid leaves the first heat exchanger means to the third fluid in the third loop; the first heat exchanger means further comprising means for receiving the third fluid in the third loop and for transferring the energy in the third fluid to the second fluid_ By a variant thereof! the first, second and third fluids are air, water in the form of condensate when entering the first heat exchanger means and steam when leaving the first heat exchanger means, and a refrig erant, respectively.
By a variation thereof, the apparatus further includes means in the third loop coupled be~ween the second heat exchanger means and the first heat exchanger for introducing additional energy into the third fluid prior to entry into the first heat exchanger means.
By another variant thereof, the apparatus further includes third heat exchanger means coupled to the first and third loops for transferring energy from the fluid in the first loop, after passing through the second heat exchanger means, to the fluid in the third loop By a variation thereof, the third loop further comprises a first compressor for introducing energy i.nto the fluid in the third loop as it leaves the second heat exchanger means; second compressor means in the third loop for receiving fluid from the first compressor means and from the secona heat exchanger means for introducing further energy into the ~ - 6 ~

~1~0~

fluid before the fluid in the third loop is introduced into -the first heat exchanger means.
By another variation thereof, the apparatus further includes de-superheating means in the third loop for desuperheating fluid receiving from the first compressor and introducing the desuperheated fluid into the second means.
By a still another vàriation thereof, the apparatus further includes a branch means in the third loop for delivering the fluid for the third loop to the desuperheating means for use in desuperheatin~ the fluid in the third loop delivered to the desuperheating means from the first com-pressor means.
By another variant thereof the apparatus incluaes dryer means comprising a rotatable drum for receiving fluid from the firs~ loop flow-ing from the first heat exchanger means and returning the fluid to first loop; and hood means positioned adjacent to the drum; means for delivering heated air to the hood; the second loop comprising means for receiving heated air leaving the hood.
By another variant thereof, each of the heat exchanger means com-prises heat exchanger means of the falling film type, By a variation thereof, circulating means are provided for con-tinuously delivering one of the fluids in each heat exchanger means from the lower end of the heat exchanger means to the upper end thereof to facilitate energy transfer between the fluids introduced into the heat exchanger m'eans~
By yet another variant thereofr selected ones of the heat ex~
changer means further comprise means responsive to the temperature and ~ 6 a ~

o~

pressure of fluid in the third loop entering the exchanger means for re~
gulating the Elow rate of the fluid introduced into the heat exchanger means.
BY another aspect of this invention, a method is provided for waste eneryy recovery comprising the steps oE; moviny a first fluid in a first loop along a heat transfer surface; moving a second fluid in a second loop along the heat transfer surface to transfer heat to the first fluid;
moving a third fluid in a third loop along a second heat transfer surface;
condensing the third fluid with the first fluid as the third fluid passes the second heat transfer surface; dividing the condensed third fluid into first and second branches in the third loop; evaporating the third fluid in the first branch with the second fluid after the second fluid leaves the heat transfer surface; thereafter evaporating the third fluid in the second branch with the second fluid; compressing the evaporated third fluid in the second branch; merging the compressed fluid in the second branch with the evaporated fluid in the first branch; compressing the merged third fluid; and thereafter returning the compressed merged third fluid to the second heat transfer surfacee By a variant thereof, the method includes the step of utilizing a portion of the condensed third fluid leaving the second portion of the heat transfer to desuperheat a compressed third fluid in the first branch before it merges with the evaporated third fluid in the second branch.
By still another aspect of this invention~ a methcd is provided for recovering waste energy from a heated fluid comprising the steps of;
a~ transferring energy from the heated fluid to first and second working fluids in a sequential fashion; b. thereafter compressing the second ~ 6 b --~09:~0 working fluid; c. desuperheating the compressed second working fluid;
d. transferring the heat energy of the desuperheated second working fluid to the first working fluid; and e. returning the second working fluid to the influence of the heated fluid to again receive energy from the heated fluid.
By a variant thereof, the method further includes the steps of: f. delivering the first working fluid to a load; and g. utili~.ing at least a portion of the first working fluid leaving the load to further increase the energy of the second working fluid before the second working fluid undergoes compression.
By a variation thereof, step (g) furtller comprises ~the steps of h. compressing the second working fluid in the vapor phase;
and i. thereafter desuperheating the second working fluid.
By another variant thereof, the method further includes the steps of j. separating the desuperheated second working fluid into liquid and vapor phase; and k. using the second working fluid in the vapor phase to perform step (d).
By another variant thereof, step (e) further includes the steps of transferring the energy of the second working fluid to the first working fluid to preheat- the first working fluid before the first working fluid receives energy from the heated fluid and the second working fluid, the second working fluid thereby being cooled to increase the amount of energy subsequently transferred to the second working fluid by the heated fluid.
By yet another aspect of this invention, apparatus is provided for recovering waste energy from a heated fluid comprising: a loop for circulating a first working fluid; heat exchanger means in the first loop for transferring energy from the first working fluid to a second working ~ - 6 c -9~

fluicl in a second loop; first evaporator means in the first loop for transferring energy from the heated fluid to the Eirst working fluid; com~
pressor means and desuperheating means in the loop for respectively com~
pressing and desu~erheating the first working fluid prior to introduction of the first working fluid into the heat exchanger means; and the heat exchanger means including means for transferring energy from the heated fluid to the first worXing fluid.
By a variant thereof, the apparatus further includes second eva~
porating means in the loop coupled to the load means for transferring energy from the first working fluid leaving the load to the second working fluid as the second working fluid le~ves the heat exchange means, and returning the second working fluid to the loop to merge with the portion of the second working fluid leaving the first evaporator means.
By a still a further variant, the apparatus further includes secona evaporator means in the loop for transferring energy from the heated fluid to the second working fluid; second compressor means and second desuperheater means in the loop for sequentially compressing and desuper-heating the second working fluid leaving the second evaporator means; and merging means in the loop for introducing the second working fluid leaving the first desuperheater means into the second compressor means.
By a variation thereof, the merginS means further comprises, separator means for separating the second working fluid received by the separator means into a vapor phase to the first and second evaporator - means; and means for introducing the second working fluid in the vapor phase into solid second compressor means~
By another variation thereof, the apparatus further includes ~ ~ 6 d ~

~1~09~0 means coupled to the separator means for divertlng a portion of the second working fluid in -the vapor phase to the first and second desuperheating means~for mixing the second working fluid entering each desuperheating means from its associated compressor means with the second working fluid received from the introducing means for uniformly desuperheating the second working fluid received from the compressor means.
By yet another variation thereof, the first and second desuper-heating means each comprise mixing means for mixing the second working fluid entering each desuperheating means from its associated compressor means with the second working fluid received from the introducing means for uniformly desuperheating the second working fluid received from the - compressor means.
By still another variant, the apparatus further includes means in the loop for transferring energy from the second working fluid, as the second working fluid leaves the heat exchange means, to the first working fluid prior to the first working fluid entering the heat exchange means.
The present disclosure thus teaches method and apparatus for waste energy recovery through the use of a working fluid which derives heat energy fram the waste energy typically exhausted from a facility upon completion of a manufacturing process step. The energy level of the work~
ing fluid is further increased by undergoing compression. The energy of-the working fluid is then utilized to develop steam at a temperature and pressure which make the steam extremely advantageous for use in a wide - variety of applications~

~ ~ 6 e 9~l~

l~aste energy from two different locations in the mech-anical process apparatus and available at the same or dif-ferent energy levels, is utilized to increase the energy of the aforesaid working fluid through the use of separate independent evaporators. The working fluid passes from one evaporator to a first compressor and then to an inter-cooling tanlc, also known as a desuperheater, for desuper-heating the working fluid. The working fluid from the second evaporator passes directly to a second compressor.
The working fluid from the output of the condenser passes to the intercooling tank. The intercooling tank desuper-heats the working ~luid twhich is in the form of a super-heated vapor) entering the intercooling device and automatically adjusts the level control between the lig~id/vapor phases therein, enabling the first-and second compressors, which operate under control of a common prime mover, to operate at significantly different temperature and pressure levels and to accommodate different mass flow rates of the working fluid.
The technique described above totally isolates the three major constituents of the system, namely the waste energy input, the intermediary working fluid and the steam produced thereby, to provide an output in the form of uncon-taminated energy in the form of steam at temperatures and pressures not heretofore-capable of being obtained through conventional recovery techniques.
The working fluid is capable of absorbing energy at high operating temperatures which causes breakdown com-ponents. However, these components occur in such small amounts as to avoid any deleterious effects upon the system components and operating efficiency.
The above technique may be used to recover waste ener-gy from a single waste energy source by omitting one of the aforementioned evaporators. Typically, a compressor is usëd for çach evaporator and~a compressor may be eliminated for each evaporator eliminated. Alternatively, multiple compressors may be utilized in order to achieve working fluid pressure levels above the capability of a single com-pressor.
~X 6 f _ ~ he techni~ues described above may be used to recover waste energy developed by a variety of industrial systems. As another embodi=
ment of an aspect oE the present invention, waste energy in the form of heated air emitted from a paper dryer system is utilizea, together with another working fluid, to generate steam.
Other novel techniques for improving the coefficient of per-formance may be employed, e.g.: p~eSsure reducing means for generating power for independent use; a multiple array of heat exchangers ana working fluid (refrigerant) loops to alter the output energy levels relative to the waste energy input; regulating the introduction of waste energy in-put; regulating the introduction of make-up steam with waste steam to maintain the characteristics of the output of the system constant; re-gulating, removing and replenishing the working fluid (i.e. refrigerant) from a working fluid (refrigerant) loop in accordance with its rate of decomposition auring use; providing means in the heat exchangers for sub-cooling the working fluid (refrigerant).
In the accompanying drawings, Fig. 1 shows a simplified diagram of a source of waste heat energy in the form of a thermomechanical pulping system;

Fig. 2 shows a si~olified block diagram of a waste heat re-covery system embodying the principles of an aspect of the present inven-tion;
Fig. 2a shows a simplified block diagram showing power generat-ing apparatus which may be substituted for the expansion valve or valves employed in the embodiments of Figs. 2, 3 and 4;
Fig. 3 shows a detailed block diagram of a TMP system of the type shown in Fig. 1 but employing only a single condensor, ~ - 6 g -Fig. 4 shows a detalled block diagram of a waste energy recovery system employing the principles of aspects of the present invention and used in combination with a hot air dryer system; `

Fig. 4a shows a detailed block diagram of an alternative em-~bodiment of an aspect of this invention for the waste energy recovery system shown in Fig. 4;
Fig. 5 shows a simplified block aiagram of a condenser which may be utilized in any of the systems of Figs. 2 through 4 for subcooling the working fluid (refrigerant) passing through the condenser;
Fig. 6 shows a block diagram of a heat exchanger array and means for selectively introducing or removing the heat exchangers from the array in accordance with changes in input levels and/or output energy demands;
Fig. 7 shows a simplified block diagram of an evaporator for use in any of the systems shown in Figs. 2 through 4 for regulating working fluid (i.e. refrigerant) flow in accordance with variations and/
or interruptions in the waste energy delivered IO the evaporator; and Fig. 8 shows a simplified block diagram of a blow-down system for use in either withdrawing and/or replenishing a working fluid utilized within the energy recovery system.
As was mentioned hereinabove, the present invention in one of its aspects is extremely advantageous for use in the recovery of waste energy, especially from systems generating tremendous quantities of waste ener~y. One such system is the thermomechanical pulping sysLem 10 shown in Fig. 1 and comprising a steaming tube 12 having an inlet 12a receiving wood chips which usually have preferably been screened to eliminate chips larger than a predetermined size; such chips have been ,~ - 6 h -subjected to a waterbath to remove foreign materials, e.g. sand. The chips enter into the steaminy tube 12, containing steam at a pressure in excess of atmospheric, for the purposè of heating and softening the-chips.
The chips are exposed to steam for a short period of time, usually less than several minutes, and are advanced by screw feeder 12b through intermediate conduit 14 to primary refiner 16~ The primary re-finer is typically comprised - 6 i -of an electric drive motor 16a having a rating of the order ol one thousand to the order of ten thousand hors~poher, which motor 16a is utilized to.provide relative motion be-tween a pair of grinding discs 16c for grinding and defiber-izing the chips to a predetermined finenèss. Screw feeder 16b feeds the chips to the region between the pair of discs 16c to undergo gr'inding, which operation generates a tremen-dous amount of heat. The grinding operation takes place - within a closed region, causing the generation of steam at a pressure level well abo~e atmospheric. The steam is vented to the atmosphere through exhaust 18. A portion of the steam otherwise vented to the atmosphere is diverted through conduit 18a to steaming tube 12 and eliminates the need for any makeup steam once the-system 10 re`aches steady operation.
The defiberized chips are then'transferred through con-duit 20 to blow cyclone 22, which comprises a substantially conical shaped member (not shown for purposes of simplic-ity). I`he defiberized chips and steam enter along a line which is tangent to the tapered walls of the conical shaped member, causing the steam and defiberized chips`to rotate at a high velocity so as to impart a centrifugal force to the heavier material Ithe defiberized wood chips), allowing the'lighter mass material (the steam) to be vented to the atmosphere through duct 24. Ducts ~8 and 24 merge at - 24a. Waste energy is vented at 25 in the form of ~team at greater than atmospheric pressure. The heavier matter in bl~w cycl~ne 22 separates from the lighter matter due to the centrifu-' - gal forces and subsequently passes downwardly along the aforementioned conical shaped member and through conduit.26 to a secondary refiner 28, which may, for e~ample, be similar to primar~ ref~ner 12. Screw feeder 26a feeds the defiberized chips from blow cyclone 22 along conduit 26.

After undergoin~ still furLher refining at refiner 28, the resulting pulp passes through conduit 30 to latency chest 32 which temporarily stores the wood pulp preparatory to;
further processing. Steam at approximately atmospheric pressure is vented to the atmosphere from outlet 34 of latency chest 32. E~haust steam at greater than atmospheric pressure is available at outlets 18 and 24 (combined at 25) while steam mixed with air at atmospheric pressure is available at outlet 34. Refiner 28 is basically the same in design and operation as refiner 16, and is comprised of motor 28a, screw feeder 28b and grinding discs 28c. Screw feeder 30a moves the pulp from refiner 28 to latency chest 32.
Figure 2 shows a simplified block diagram of a waste energy recovery system 40, embodying the principles of the present invention and compr.ising condenser 42, evapora-tors 44 and 46, compressors 48 and 50, operated by a common prime mover 52, and intercooling tank 54. Dirty, lower pressure steam mixed with air and derived from the vent 34 of latency chest 32, enters evaporator 44 at an inlet 44a and passes over the energy transfer members (not shown) carrying the working fluid of the system, which worlcing fluid passes over the energy transfer members ~not shown) of the evaporator 44 at inlet 44b and leaves the coils of evaporator 44 and moves from outlet 44c through conduit 56 to the input of the f~rst compressor 48. The output of compressor 48 passes through conduit 58 to the vapor inlet 54a of desuperheater 54. The working fluid, which may, for example, be a refrigerant in the form of superheated vapor, enters into the portion of desuperheater 54 containing the liquid phase of the working fluid which serves to desuper-heat the vapor phase of the working fluid for a purpose to be more fully described. Control means 60 injects worl~ing fluid (refrigerant) in the liquid phase into desuperheater 54 to partially desuperheat the vapor in tank 54 while evaporating the additional working fluid in the liquid phase.

- 1~8(~910 Thc ~ icl l~hase of ~lle w~ rlllid pas.s~s t:hl-o-lgh con~luiL 64. A portioll oL Lhe l.ic~uid Ih.3~ Or ~he worli.ng f]~ moving Lllruugll co)lcl~lil 64 p.3SSL`S ~hrougll condui.t 66 and ente~s i.nlet 46a of -3 falling film evaporator h6. ~he remaining portion of the wo2-lci.ng fluid in the liquid phase moves through conduit 68 and adj~3stable expansion valve 70 which valve reduces the ~ressure of ~he worling fluid as it passes through valve 70 and enters ~he inlet 44b of evaporator 44.
~vaporator 46 is similar to evaporator 44 and i.s provided with ener~)~ transrer sl.irfaces (not shown for purposes of simplicity) one of which su-faces the working fluid passes over in moving from the inlet 46a to the outlet 46b of evaporator 46. ~aste steam de-ived from vent 25 for example enters evaporator.46 flt 46c alld passes over the aforementioned surfa~es, leaving evaporator 46 at outlet 46d. The outlet 46b of evaporator 46 is couplecl to the inp~3t of the second compressor 50 through conduit 73.
The vapor plase of the working ~].ui.d within intercooling.
tank 54 passes through conduit 72 and merges with the worlcing flui.d passi.ng througll conduit 73 after heing emitted from evaporator 46. The orki.ng f].uid emerges ~rom compres-sor 50 and passes throl3gh conduit 74 to the inlet of conden-ser 42.
The operation of the heat recovery s)~stem in ~ig.

2 is as follows:
The worlcing fluid-has its pressure reduced by expansion valve 70 causing the wor1<ing fluid to enter into the li.quicl/-gas phase as it enters into evaporator 44. I.ow pressure steam mixed with air and derived from the thermomechanical pulper (TMP) latency chest 34 (see ven~ 34 ~ig. 1) trans-fers its energy (in t;l~ foL-r~ oE heat) to the worlcing rluid.
The temperature and pressure of the worl<ing fluid remain substantially constant at the inlet and outlet end of .
evaporator 44. However the enthalpy of the working ~luid is significantly increased because of a phase change.

_ g _ ~ O~

The worlcing fluid undergoes a first stage of compres-sion by passiTlg through a compressor 48 which si~nificantly increases the temperature and pressure of the working fluid while causing only a mild increase in its enthalpy.
The superheated wor]<ing fluid then enters into intercool-ing tanlc 54 wllere it is desuper11eated. The pressure of the working fluid is maintained substalltially constant as it moves between the outlet end of the firs~ compressor 48 and the inlet end of the second compresser 50 through desuperheater 54, w11ile undergoing a reduction in tempera-ture and enthalpy. The second compressor 50 significantly increases the temperature and pressure of the worlcing fluid derived from desuperheater 54 and evaporator 46 and delivers the working fluid to condenser 42. The working fluid transfers its energy to hot water entering inlet .- 42c, which hot water is derived from either a fresh water source or fl-om a condensate return provided in the system (not shown) where the clean steam is being utili~ed. The temperature and pressure of the hot fresh water passing through condenser 42 is maintained substantially constant.
However, the enthalpy of the water is increased signifi-cantly. The steam generated as a result of the condensation of the working fluid as it passes through condenser 42, may be used in any one of a wide variety of applications, such as paper dryer drums and paper dryer hoods, for e~ample, as well as any other ~plicati~1ls requiring steam at pres-sures of the order of 50 PSIA, or ureater.
The working fluid leaving condenser 42 which is now in the liquid phase, passes from conduit 76 through expan-sion valve 78 which reduces the pressure of the workingfluid. The working fluid, in the liquid phase, enters tank 54 through control means 60 to desuperheat the working fluid in the vapor phase, ~hich cooperates to evaporate the additional wor~ing fluid introduced into tank 54 through control means 60.

The in~ercoolillg tank 54 ellables colllpressors 4~ and 50, wllich are commollly driven by prime mover 52, to operate on worlci.ng fluids having differcnt temperatul~e and piessure levels \~ithout causing ulll)al.anced conditions.within the system. Compressors 4.~ ancl 50 may also be drivel- by scparate prime movers wi.thollt altcring the ad\!alltagcs Or the inven-tion. This technique allows the mass flo~ rates of compres-sers 48 and 50 to be signifi.calltly difrerent for ~he purpose of enabling evapol-ltors 44 and 46 to handle ~7ast~e energy from sources ~hose temper.lture and pressure levels are significantly different from one another. ln addition, the waste energy recovery utili~es a ~orking fluid capable of operating at temperat-ures well above 260F. and up to maximum operating temper.ltures over 4G3F. without experienc-ing any significant breakdown, thereby enabling thë conver-sion of waste energy in~o steam at pressure levels and operating efficiencies not heretofore obtainable through conventional techn:iques. ~he waste energy sources may be coupled to different evaporators ~rom those desi~nated .above~ if desired~ without depal-ting from the sco~e.of aspects of the present invention.
rhe arrangement of Fig. 2 may hc modifi.cd to accommo~
date applicati.ons i.n which ~i~aste e~nergy is derivecl from a single source, by omitting evaporator 46 and diverting all of the wol-l<ing ~lui.d in the liguid phase derived from intercooling device 54, 50 conduit 68 and hence to evapora-tor 44. ~he evaporator 44,compressor 48 and intercooling device 54 may be adjusted to accommodate the particular type of waste energy receivec] by evaporator 44.
~0 Other modifications may be introduced into the embodi-ment of Fig. 2. For e~ampl.e, it is preferred that the desuperheater 54 be positioned relative to evaporator 46 so th~t the liquid level in evaporator 46 is at a greater , ~ O~

height thall the licluid le\/~l i.n the des-lperlleater 54 ~c provide the necessary pressure levels. ~s another a~terna-tive, a pump 71 may be placecl in conduit 64 to provide and maintain the necessar~ pressure diferential between the liquids in evaporator 4G and desuperheater 54.
The expansion valve 70 of ~ig. 2 may be replaced by turbine or fluid mo~or 82 of ~ig. 2a for receiving working fluid at inlet 82a and delivering working fluid - through its outl.et 82b to tlle inlet of evaporator 44. The fluid motor 82 thus produces power at its output shaft 82c which may be utilized for the heat pump compressor as well as providing input power to any load within the vicinity of the equipment. The substitution inc.eases the system coe~fic-ient of perfornance (COP) due to the power e~tràcted from the turbi.ne 82.
The working fluid.(refri.gerant) leaving the condenser 42 of Fig. 2, for example, is typically near a saturated liquid state. By utili~ing cooler, moist air present within the loop of the energy recovery cycle Ol- other waste stream, . it is possible to subcool thc working fluid (refrigerant.) leaving the conclPn~r; thPrehv greatly increasing the coefficient of performancc of the cycle since the work per pound of worki.ng fluid (refrigerant) for compression remains the same wlliie the heat removed per pound in the condenser increases. The coefficient of performance is further enhan-.ced since the num~er of pounds of working fluid is alsoreduced. Considerin~ Fi.g. 5 in detail wherein like e].ements as between Figs. 2 and 5 are designated by like numerals, .-. compressor 50 compresses thc worki.nx fluid (refri.gerant) delivered thereto by condui~ 73 and introduces the com-pressed worlcing fluid into condenser 42 through conduit 74.
The working fluid (refrigerant) entering at 42a transfers its energy through transfer surface 4~e~to the condensate .

(39~
crlte)-in~ a~ 42c Lo prc)d~lce .steam appearing aL ou~le~ 42d ~he condellser 42 is se~menLed so that a poltion 42f thereof is s~parated from the remaining portion of the condenser 42 and is provided with inlet 42g which receives waste energy such as, for example, from the waste energy stream, or moist air entering at 42g, and which i`s adapted to absorb heat energy from the ~orking fluid (refrigerant) through transfer surface portion 42e' and thereafter passing out of condenser 42 through outlet 42h. The working fluid (refrigerant) is thus s~bcooled just prior to leaving condenser 42'at 42b and enLering into conduit 76, thereby greatly increasing the coefficient of performance since the work per pound provided by the worlcing fluid (refrigerant) upon compression remains the same, whereas th~ heat removed ~er pound by ~he con-denser increases. ~hus the condenser arrangement ~i2' OLFig. 5 may be substituted for the condenser 42 of Fig. 2, yielding an increase in COP.
- Fi~. 6 sho~s an array of heat exchange units 86, 94, 108 connected to one another in a manner to be more fully described and which can be selectively introduced or removed from the array in accordance with variations in temperature -levels in the system in order to optimize system performance at such levels.
Considering the arrangement of Fig. 6, evaporator 86 is included in the lowest pressure refrigeration loo~ ~7 consisting of conduit 88, compressor 90, conduit 92, evapora-tor 94, conduit 96, expansion valve 98 and conduit 100~
an appropriate working fluid (refrigerant) being circulated within the aforesaid closed loop 87. The temperature and pressure of the working fluid leaving evaporator 86 enters into compressor 90 and the energy generated thereby is transferred to another working fluid in heat exchanger 94.

The condensed work-ing fluid (refrigerant) leaving ileat exchanger 94 through conduit 96 is then throttled through valve 9c8 before being re~urned to evaporator 86 which receives waste energ~ at input cn6a. This energy is transfer-red to the worl<ing fluid ~re~rigerant) and thereafter thewaste energy carrier such as, for example, steam, e~its from evaporator 86 at 86b. The working fluid (refrigerant) enters evaporator 86 at S6c and leaves evaporator 86 at outlet 86d.
The compressed working fluid passing through conduit 92 enters heat exchanger 94 at inlet 94a and leaves heat exchanger 94 at outlet 94b. ~ ~ -A second working fluid (refrigerant) loop 101 iscomprised of heat exchanger 94, conduit 102,- compressor 104, conduit 106, heat e~changer 108, condui~ 110, throttle valve 112 and conduit 114. This closed loop 101 may contain a refrigerant which is preferably different from the refriger-ant in the first-mentioned loop 87. The same series of processes set forth above with regard to loop 87 are per-formed within the second loop 101. The loops 87, 101 allow several refrigerants to be used in order to optimize perform-ance at different temperature levels. Additional loops may be utilized. For example, heat exchanger 108 may in turn form part of a third closed loop 131 which, for purposes of simplicity, is shown only as including conduits 116 and 118 and valves 128, 130.
A particularly advantageous feature of the multiple stage arrangement of Fig. 6 is the heat exchange unit 94 which includes two independent working fluid (refriger-ant) loop passages as well as inlets 94c and 94d for receiving a 1:hi~d workin~ ~luid. For e~ample, loop 101 may be inactivated by turning off compressor 104 and closing valve 112. Valves 120 and 122 are then opened-to permit condensate to be admitted through valve 120 into heat , ~og~

exchangel- 94 which transfers energy from the fluid in loop 87 .o the condensate entering at 94c. Heat exchanger 94 discharges steam at outlet 94d through valve 122: Valve:; 120 and 122 may be operated either manually or automatically.
The above arrangement allows the generation of steam at a lower pressure b~ cutting out second loop 101 and/or at a higher pressure by re-establishing the second closed loop 101 by closing valves 120 and 122, opening valve 25, turning on turbine 104, opening valves 124 and 126 and closing valves 128 and 130. A third loop may be created by closing valves 124 and 126 and opening valves 128 and 130 and coupling conduits 116 and 118 into a~third closed loop substantially identical to closed loops 87 and 101. The arrangement of Fig. 6 has a great deal of flexibility since steam can be generated at one or several different pressure levels either separately or simultaneously without any deleterious effect to the coefficient o-f performance. Thus, for example, loops 87 and 101 may both be completed and - steam may be generated by heat exchangers 94 and 108 simply by opening the pairs of valves 120-122 and 124-126 to develop steam at two different pressures.
It should be further understood that a fluid other than condensate can be admitted through conduit 94c of heat exchanger 94. The flow through heat exchanger 108 operates in a fashion substantially similar to that of heat exchanger 94. Conduits 118 and 116 guide the flow of working fluid ~refrigerant) in a third stage closed loop 131, if desired. It should further be noted that working fluid in the highest pressure loop can be water, in which case the condenser in that loop can be omitted, liquid can be fed into the condenser of the next lowest prèssure loop and high pressure steam removed from the compressor exhaust.
~or example, condenser 108 in loop 101 can be eliminated, liquid may be introduced into inlet 94e of condenser 94 and high pressure steam may be derived from the exhaust of compressor 104.

Fig. 7 shows an arrangement for compensating for variations in waste energy delivered to the recovery system.
In the event that waste energy available at conduit 134 for delivery to evaporator 136 varies, the exit conditions at conduit 142 will vary. To remedy this problem, the arrangement 133 of Fig. 7 is provided with an au~iliary conduit 144 for receiving steam from a make-up source (not shown) è.g., a boiler. Temperature sensor 146 coupled to line 142 automatically regulates valve 148 ~o control the introduction oE make-up steam in auxiliary line 144 to be admixed with the waste heat stream introduced through conduit 134 as a function of the degree of superheat of the working fluid (refrigerant) in conduit 142.
As was described hereinabove, the energy recovery system employed for recovering waste energy from a TMP
~ ~ system, for example, must be capable of coneinuous operation on a day-to-day basis. However, since the working fluid (refrigerant) is exposed to high temperature levels during system operation, the working fluid (refrigerant) may -decompose or otherwise form products of reactions with the materials in contact with the working fluid.
Fig. 8 shows a blow-down system lS0 which may be either of a manual or automatic design, for use in withdraw-ing fluid from the working fluid (refrigerant) on either a continuous or intermittent basis. The arrangement of Fig. 8 shows a working fluid-(refrigerant) line 152. A tanlc 156 is coupled to conduit 152 through line 158. Valve 154 may be opened periodically at intervals determined by past experi-ence with the system so as to remove fluid from conduit 152, which is collected in tank 156. When valve 154 is closed, the contents of tank 156 may be disposed of.
The system may be operated on an automatic basis by providing monitor 160 which automatically opens valve 154 based upon the presence of a measured rate of decomposi-tion product of the workin$ fluid belng used.

.

Wor~<ing ~luid may also ~e added to the line 152 by means of a storage tanli 162 coupled to conduit 152 through conduit 164. Valve 166 may be opelied to introduce additional worlcing fluid into conduit 152. Additional working fluid may be added in an automatic fashion through the employment of monitor means 168 on sensing the presence of a predetermined condition, such as, for example, the amount of workin~ fluid which has been withdl-awn and diverted into tank 156. As an alternative, valve means 166 may be coupled to monitor 160.
Fig. 3 shows an alternative waste recovery system 170 which constitutes the aforementioned modification of the system of Fig. 2 in which only a single evaporator is employed. Wherever appropriate, like elements`have been designated by like numerals.
Chip cyclone 172 receives chips being blown from storage which pass through metering de~ice 174 for deposit on to conveyor 176 and ultimate introduction into washer- -drainer 178. The moistened chips are then delivered to feed screw 180. The chips are admixed with processed steam introduced by conduit 182 into rotary feed valve 184, at which location the chips and processed steam are admixed.
The chips enter into steaming tube 12 and are conveyed therealong by screw feeder ~2b driven by motor 186 whose drive pulley 186a is coupled to screw feeder pulley 190 by closed loop belt 188. The first stage refiner 16 defiberizes the wood chips in the manner previously described. The defiberized material passes through blow valves 192 and conduit 194 to enter into blow cyclone 22 operatin~ in the manner previously described. Screw conveyor 26 deli~ers the defiberized material to a secondary non-pressurized refiner stage 28. The defiberized material then passes throu~h conduit 30 and enters into latency chest 32.
The steam introduced into steaming tube - 17 _ 12, wllicll is also prcscnl in ~lle first sta~e refincr 16, conduit 194 and b]ow e;el;)i-,.- 22, is ~enled through conduits 18 and 24 in the same manncr as was previously desc1-ibed ~ Valve 196 may be closed or opened to any desired valve control position to regulate the pressure levels of the steam within steaming tuhe 12 and blow cycl'one 22. Tlle waste steam passes through vent 25 and enters into inlet 45c Of evaporator 45. Thc waste steam ~asscs over heat transfer members 4se` in e~aporatol- 45 wllich may be a falling film evaporator, in which worl<ing fluid (refrigerant) in the lower portion of the evaporator 45 passes through outlet 4sg' and is delivered by pump 197 to ~he upper end of evaporator~
45 where the working fluid (refrigerant) is e~sed to flow over the heat transfer surfaces of members 45e. Valve 198 is utilized to regulate the flow rate at which the'working - fluid is circulated The waste steam exits from evaporator 45 at outlet 45d where it is vented to the atmosphere through vent 200 The closed loop working fluid (refrigerant) conduit 76 'enters evaporator 45 at inlet 45a and exits at outlet opening 45b Throttle valve 206 regulates the flow rate of refrigerant entering evaporator 45 A level transmitter 208 monitors the working fluid (refrigerant) level in evaporator 45 and provides a signal to level instrument control 210 which provicles a visually observable r'eading of the working fluid level and automatically controls throttle valve 206 through line 210a to regulate flow rate therethrough The working fluid (refrigerant) in the vapor phase exits through conduit 56 and enters into the first stage compressor 48 The compressed refrigerant then enters into desuperheater 54 to be desuperheated and undergoes a second stage of compression by compressor 50 The output of the second compressor stage 50 enters into inlet 42a of conden-sor 42 whlch may also be of the falling film type The _ 18 -worl<ing fluid ~ransrers its heat ~nel-csly to ~eed water introdLIced thro~lgll ]ille 212, valvc 2]4, t;lnl< 219 ancl inlet 42c. ~he worlcing f]u;d tratlsEel-s itC~ energy to the Leed water to ~eneratè steam at outlet 42d. Tlle wori<ing fluic]
passes from outlet 42b of condenser 42 into working fluid surge tank 232 where it is deliverecl througll collduit 76 simultaneously to evaporator 44 and to desuperheater 54. The flo~ rate o worl<ing fluid througl~ conduit 78 is controlled by temperature indicator 222 whose output 222a is coupled to temperature indicating controller 224 having outlet 224a for adjustment of throttle valve 226.
Tank 219 serves as an intermediate storage tank from which feed t~ater is circulated throucvh condenser 42 by pump 238, the flow rate being regulated by control valve 240. The working fluid derived from condenser 42 thus serves the dual functions of supplying working fluid for evaporator 44 which transfers waste energy thereto, as well as providing worlcing fluid ~or desuperheating the superheated working fluid compressed by first compressor stage 48.
Fig. 4 shows still another alternative embodiment 250 of an aspect of the present invention in \~hich the ~aste energy recovery techniques describ~d hereinabove are utili~ed in a dryer system 249 comprised of a very large diameter rotating drum 252. A web to be dried (not shown) is passed about the surface of drum 252 ~.~hich is heated to dry the web. A hood 250 is arran~ed above the u~per half of drum 252 and, although not shown in detail, contains nozzles for deliverinsJ air toward the surface of drum 252, as well as 30 for removing air for delivery ~o the exhaust line. An air heater 254, supplied with fuel through line 256, receives air delivered by fan 258 as ~ell as combustion air through line 260, delivered to heater 254 by blower 262. Fuei oil in ~80~

]ine 256 is atomizecl by steam diverted rrom a st~am line to be more fully described tllrough conduit 257. If natural gas is used, atomization is not necessary. Heater 254 heats the air up to temperatures of the order of 900~. through direct combustion and delivers the heated air through conduit 254a into the inlets 250a and 250b of hood ~50. Air exits from hood 250 through outlets 250c and 250d at a temperature of the order of 750F. ancl passes through conduit 264 to exhaust fan 266 which delivers the high temperature air through conduit 26~ to inlet 270a of steam generator 270.
The capacity of exhaust fan 266 is substantially equal to the capacity of combustion blower 262 in order to assure balance within the system. Temperature and pressure indicat-ors may be used t~ monit~r the ~ir in c~nduit 268.
- ~ 15 The steam generated by steam generator 270 exits at outlet 270d and enters conduit 272 where it is introduced into the inlet of steam compressor 274, driven by motor 276. The output of steam compressor 274 is introduced directly into rotary drum 252 to heat the drum surface 252a for drying the web passing about drum surface 252a.
A combination of steam and water is emitted from drum 252 and enters conduit 278 where it is int-roduced into separator 280 which separates the steam and water, delivers the water from pump 282 through conduit 284 .o the conden-sate inlet 286. The steam exiting from separator 2~0 is introduced through conduit 288 into steam compressor 274.
As was previously mentioned, a portion of the ~steam output-ted from separator 280 is diverted through conduit 257 to atomize fuel oil passing throu~h fuel delivery line 256 As was mentioned hereinabove, the extremely high temperature air is utilized to convert condensate into steam. The air does not give up all of its heat ener~y and the system takes advantage of this by coupling air :

- _ 20 -ou~le~ 270~ ~hro~lgil con(hliL 29~ into ill]Ct 2~2a of high temperature evaporator ?92. Evaporator 292 is prefera~ly of the falling film evapor.ltor type mentione(l previously.
Working fluid collected near the bottom of evaporator 292 passes through conduit 294 al-d is delivered by pump 296 to the upper end oL evaporator 292 for continuous circula-tion thereof. In one preferred embodime>nt, the rate of flow may, for example, be of the order of 400 gallons per hour. Temperature alld pl-essure indicators may be provided for monitoring wor~in~ fluid within the .. . . . ...... . . ..... . _ -- . .
circulation line 294. Circulation may ~è regulated and/or terminated by operation o~ pump 296 and valve 302.
Working fluid level within evaporator 29~ is measured by level detector 304. The level detector 304 is coupled to level indicating controller 306 which utilizes the ]evel condition to control level valve 308 for regulating the : introd~lction of working fluid into evaporator inlet 292c.
- Working fluid introduced into evaporator 292 exits throùgh separator 310 and outlet opening 292d, entering into the input of second stage vapor compressor 312 through conduit 314. Working f]uid in the liquid phase reenters evaporator 292 through line 307.
The hot air, which still contains-a significant level of heat energy, then passes througll out]et 292b and conduit 316 into the inlet opening 318a oL low temperature evapora-tor 318. Low temperature evaporator 318 is substantially similar in design to high temperature evaporator 292 in that it is of the falling film type and is provided ~ith a circùlation conduit 320 for circulating working fluid (refrigerant) by way of pump 322. Ievel detecting device 330 measures the level of working fluid (refrigerant) within evaporator 318. Level indicating controller 332 monitors the refrigerant level to control the operation of level valve 334, thereby controlling the flow rate of refrigerant introduced into evaporator 318 at inlet 318c.

The hot air introduced through inlet 318a of evaporator 318 ~ransfers its heat energy to the aforementioned working fluid (refrigerant) and exits through outlet opening 318b.
~ Separator 338 causes condensate to pass through line 3~0 while allowing air to exi~ ~hroug~ vent 342. The worl;ing fluid (refrigerant) which has absorbed heat energy from the hot air passes through separator 318e. Any working fluid (refrigerant) in the liquid phase is returned to evaporator 318 through line 318f. The working fluid (refrigerant) in the vapor phase passès through conduit 344 where it enters into the first stage compressor 346. Compressors 312 and 346 are shown as being driven in common by motor 348. However, the compressors 312, 346 may also be driven by separate motors, if desired. The working fluid introduced into compressor 346 leaves outlet 346b and enters into desuper-heater 350. I`he desuperheated working fluid exits from - desuperheater 350 where it enters-inlet 312a of second stage vapor compressor 312 whose output 312b passes through conduit 352 into inlet 270e of steam generator 270.
Steam generator 270 is unique in that the steam genera-tor is divided into two segments, the first of said seg-ments, namely the upper half thereof, being utilized to generate steam by hot air, while the lower segment is -utilized to generate steam through the use of a working --fluid.
The generator 270 may be replaced by two separate heat exchange units, if desired.
The working fluid transfers its heat energy to the condensate that generates steam. The condensed worlcing fluid leaves the steam generator 270 at outlet 270f and passes through valve 354 where it enters into surge tank 356 one outlet of which, 356a, is coupled to line 336 and the other outlet of which, 356b, is coupled through conduit 358 and valve 360 to the control member 362 of desuperheater .

~ o~

350. Temperature indicator 364 measures the temperat-re leve~ in des ~erhe7t~r 350. The ou~put si~nal is coupl~d to temperature indicating controller 366 which operates valve 360 to regulate the ~low rate of refri&erant in the liquid phase into desuperheater 350;
As was mentioned hereinabove stearl generator 270 is preferably of the falling film type. Condensate entering into the circulation line 370 is circulated from the bottom of steam generator 270 to the top thereof b~ pump 372. The level of condensate introduced into steam generator 270 is monitored by level transmitter 374 whose output is coupled to level indicating controller 376 whieh opera~es valve 378.
In a similar fashion level transmitter 380 monitors the level of working fluid (refrigerant) within steam generator 270. Its output is monitored by level indicating controller : 382 which controls valve 354 regulating the rate of flow of - working fluid leaving steam generator 270.
As was mentioned hereinabove the steam generated by steam generator 270 and available at outlet 270d first passes through separator 270g which separates the steam from the condensate returning condensate through line 270h to steam generator 270. Steam is delivered through line 272 to steam compressor 274 which compresses the steam and thereafter introduces the compressed steam into drying drum 252 through conduit 275.
The generated steam_may also be provided to other utilization devices through line 386.
Fig. 4A shows an alternative arrangement 249 for the waste energy recovery system 249 of Fig. 4 in which an evaporator 490 is substituted for the compressor 2/4 and prime mover 276 shown in Fig. 4 as will be more fully described. Like elements have been designated by like numerals as between Figs. 4 and 4A and detailed descrip-tions of operation of such elen-ents will be omitted herein-below for purposes of simplicity.

JLl~O~

rrhe hot air rrom unit ~50 enters line 264 and is ~rged ~long COll~Ui t 268 ~ L)lower 266. 'l`he hot air transfers its heat energy to the condensate entering steam genel-ator 270.
The hot air, which still contains a significant amount of heat energy, sequentially enters high temperature evapo-rator 292 and low temperature evaporator 318. Thereafter the air is vented to the atmosphere at vent 342.
The worlcing fluid (refrigerant) leaving eVaporatol 292 through conduit 314 merges with working fluid in conduit 509~derived from b]ow through steam evaporator 490. These two flows are then mer~ed with desuperheated ~orking fluid from the outlet 350b of desuperheater 350 and the three merged fluid flows enter inlet 356a`of`surge tank 356.
- 15 Worlcing fluid in surge tank 356 which is in the vapor -~- phase leaves through outlet 356b and enters compressor 312. Working fluid in the liquid phase leaves surge tanlc 356 at outlet 356c and merges with working fluid in line 514. The merged fluid flows are pumped :into conduits 336 and 518 by pump 474. Some of the worlcing fluid in the liquid phase leaves surge tank 356 at outlet 356d and is pumped into conduit 358 by desuperheat-er pump 4760 The working fluid in conduit 358 divides into branches 358a and 358b to be passed through the super-heated working fluid entering desuperheaters 350 and 46~ -by means of control head~`362 and 462, respectively. Mixers 351 and 461,in the form of rotating vanes~provide intimate m xing of the working fluid in the superheated vapor phase : -with the liquid phase.
As was set forth al~ove~ the desuperheated workin~
fluid leaving desuperh~ater 350 enters surge tank 356.
The working fluid in the vapor phase leaves surge tank 356 through outlet 356b. A]l of the excess working fluid , ` :~, - , . ..

_ 24 -in the liquid phase is directly returned to the evaporators 252 and 318, through outlet 356c, except for the s~all portion thereof utilized for desuperheating, delivered from outlet 356d.
. _ , ...................... . . . ... . .
I`he compressor 312 receiving the worlcing fluid from surge tank 356, further compresses the working fluid and passes the superheated working flui.d to desuperheater 460. The desuperheated ~orking rluid then passes through ..:
adjustable valve ~!70 ~0 .^duce .he pressure of the working ` fluid before it enters the lower portion of steam generator 10. 270 through inlet 270e ;
The working fluid, after transferring its heat energy to the condensate in steam generator-270, enters into condensate preheater 472 to pre-heat the condensate passing therethrough and before the condensate enters steam gener-ators 270 and 490 through conduits 508 and 510, respectively. The working fluid leaves pre-heater 472 and merges with the working fluid in the liquid phase leaving sur~e tank 356. The transfer . -of heat energy from the working fluid leaving steam gener-ator 270 lowers the enthalpy of the working Eluid and thereby allows the working fluid to piclc up more heat energy in evaporators 290 and 318, significantly reducing the amount of working fluid needed, thereby reducing the size and capacity of evaporators 292 and 318.
Condensate tank 478 and steam.generator 270 derive preheated condensate from condùit 506. Separator 270h returns condensate to the bottom of steam generator.270.
Condensate make-up is derived at inlet conduit 507 depending upon the level of condensate in tank 478, which is monitor-ed by level sensor 480, and controller 482, serving to operate 3b -valve 484.in accordance with the level in tank 478. The level 479 in tank 478 reflects t,e level 271 in ta~k 270.

~o~

Condensate from separator 280 thlougl- pump 282, and evaporator 490 through steam trap 486 is dèlivered to condensate preheater 472 through conduit means 520, 510, 508 and 472b.
The steam developed by steam generator 270 is trans-ferred directly to drum 252 through conduit 272.
The steam and condensate leaving drum 252 through conduit 278 enters separator 280. The steam separated out is ` delivered to inlet 490a of steam evaporator 490. The steam entering blow-down steam evaporator 490 transfers its heat energy to the working fluid delivere~ thereto through conduit 518. The heated ~orkin~ fluid ~eaves steam generator 490 at outlet 490d and passes through conduit 509 which - -merges with conduit 314 to deliver working fluid to surge tank 356.-The embodiment of Fig. 4 provides a recovery system in which both hot air and refrigerant are utilized-to generate steam. The initial temperature level of the hot air ~
as it leaves hood 250 is sufficient to generate steam directly. The hot air is then used in additional heat exchanger (evaporator) units to transfer still further heat energy to a working ~luid (refrigerar.t). The greater heat energy level is transferred to the working fluid (refrigerant) passing through high temperature evaporator 292, while the lesser~level of heat energy is delivered to --the working flùid passing through low temperature evaporator 318. As a result, the woricing flùid emitted from evaporator 318 under~oes two stages of compression, as well as an intermediate stage of desuperheating, while the working fluid leaving high temperature evaporator 292 undergoes only a single stage of compression. The working fluid delivered from low temperature evaporator 318 and ~caviTlg compressor 346, however, is cornbined with the w~rking fl~id delivered IroD~ high temperature evaporator 292 in the second stage vapor compressor 312, the combined streams of working f~uid being introduced to that portion of the steam generator utilizing the working fluid to generate steam.

:
'` . ' . ~' - 2~ -

Claims (37)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Apparatus for improving the coefficient of performance in an energy transfer system, comprising:
heat exchanger comprising first inlet means for receiving a pressurized fluid being delivered thereto from a loop for conveying said fluid, and first outlet means for returning the fluid to said loop;
second inlet means for receiving a second fluid from a second loop and second outlet means for returning the second fluid to said second loop;
said heat exchanger including said transfer means for transferring energy from the fluid in said first loop to the fluid in said second loop;
third inlet means for receiving a third fluid from a third loop and third outlet means for returning the third fluid to said third loop; and means responsive to the passage of said third fluid through said heat exchanger for subcooling the first fluid before returning the first fluid to said first loop.

2. Apparatus for improving the coefficient of performance in an energy transfer system, comprising:
heat exchanger comprising first inlet means for receiving a pressurized fluid being delivered thereto from a loop for conveying said fluid, and first outlet means for returning the fluid to said loop;
second inlet means for receiving a second fluid from a second loop and second outlet means for returning the second fluid to said second loop;
said heat exchanger including said transfer means for transferring energy from the fluid in said first loop to the fluid in said second loop;
third inlet means for receiving a third fluid from a third loop and third outlet means for returning the third fluid to said third loop; and means responsive to the passage of said third fluid through said heat exchanger for subcooling the first fluid to remove the useful energy therefrom before returning the first fluid to said first loop.

3. The apparatus of Claim 2 wherein said first fluid is a refrigerant;
said second fluid is a condensate capable of being converted to steam by said first fluid; and said third fluid comprises moist air.

4. Apparatus for altering the transfer of energy in accordance with the energy changes in the input or output fluid comprising:
an array comprising a plurality of heat exchangers;
a plurality of loops coupling each heat exchanger with next heat exchanger in said array;
each heat exchanger having first fluid receiving means and second fluid receiving means for transferring energy from the fluid passing through said first fluid receiving means to the fluid passing through said second fluid receiving means;
each of said loops being coupled to second fluid receiving means of each heat exchanger and the first fluid receiving means of the next adjacent heat exchanger in said array;
each of said loops comprising means for increasing the energy stored in the fluid passing therethrough;
selected ones of said heat exchangers further comprising third fluid receiving means for transferring energy from a fluid passing tyhrough said first fluid receiving means to a fluid passing through said fluid receiving means;
means for selectively deactivating each loop to disconnect each heat exchanger from the next adjacent heat exchanger thereby reducing the number of heat exchang-ers actively operating in the array.

5. The apparatus of Claim 4 wherein each deactivating means comprises a valve which may be opened to couple its loop between adjacent heat exchangers associated with said loop and closed to decouple the adjacent heat exchangers associated with said loop.

6. The apparatus of Claim 4 further comprising valve means for selectively coupling the third fluid receiv-ing means to its associated fluid supply enabling at least a portion of the energy to be transferred to the fluid passing through said third fluid receiving means from fluid passing said first fluid receiving means and for decoupling-the third fluid receiving means from its associat-ed fluid source for enabling energy to be transferred from the fluid in said first fluid recovery means to the fluid in said second fluid recovery means.

7. The apparatus of Claim 6 wherein each of said loops comprises valve means and means for increasing the energy stored in the fluid in said loop as it passes therethrough.

8. The apparatus of Claim 6 wherein each of said loops comprises valve means and compressor means for increasing the energy stored in the fluid in said loop as it passes therethrough.

9. The apparatus of Claim 6 wherein the energy stored in the fluid introduced into said third fluid receiving means is transferred to the fluid in said second fluid receiving means when said valve means are closed.

10. Apparatus for recovering waste energy comprising;

a first loop for receiving a first fluid vented from a utilization device delivered to said first conduit at an elevated temperature level;
first heat exchanger means, having first means for receiving said first fluid from said first loop and second fluid receiving means;
a second loop for delivering a second fluid to said second fluid receiving means, said second fluid receiving means comprising means for transferring energy from the fluid in said first fluid receiving means to the fluid in said second fluid receiving means;
a third loop containing a third fluid;
second heat exchanger means coupled to said first and third loops for transferring energy from the fluid in said first loop as said fluid leaves said first heat exchanger means to the fluid in said third loop;
said first heat exchanger means further comprising means for receiving said third fluid in said third loop and for transferring the energy in said third fluid to the fluid in said second loop.

11. Apparatus for recovering waste energy comprising:

a first loop for receiving a first fluid vented from a utilization device delivered to said first conduit at an elevated temperature level, a second loop containing a second fluid;
a third loop containing a third fluid;
said first, second and third loops being indepen-dent of one another;

first heat exchanger means having first fluid receiving means for receiving said first fluid from said first loop and second fluid receiving means for receiving said second fluid from said second loop;
said second fluid receiving means comprising means for transferring energy from the first fluid in said first loop to the second fluid in said second loop;
second heat exchanger means coupled to said first and third loops for transferring energy from the first fluid in said first loop as said fluid leaves said first heat exchanger means to the third fluid in said third loop;
said first heat exchanger means further comprising means for receiving the third fluid in said third loop and for transferring the energy in said third fluid to said second fluid.

12. The apparatus of Claim 11 wherein said first, second and third fluids are air, water in the form of condensate when entering said first heat exchanger means and steam when leaving said first heat exchanger means, and a refrigerant, respectively.

13. The apparatus of Claim 12 further comprising means in said third loop coupled between said second heat exchanger means and said first heat exchanger means for introducing additional energy into said third fluid prior to entry into said first heat exchanger means.

14. The apparatus of Claim 11 further comprising:
third heat exchanger means coupled to said first and third loops for transferring energy from the fluid in said first loop, after passing through said second heat exchanger means, to the fluid in said third loop.

15. The apparatus of Claim 14 wherein said third loop further comprises a first compressor for introducing energy into the fluid in said third loop as it leaves said second heat exchanger means;
second compressor means in said third loop for receiving fluid from said first compressor means and from said second heat exchanger means for introducing further energy into said fluid before the fluid in said third loop is introduced into said first heat exchanger means.

16. The apparatus of Claim 15 further comprising desuperheating means in said third loop for desuperheating fluid received from said first compressor and introducing the desuperheated fluid into said second com-pressor means.

17. The apparatus of Claim 16 further comprising a branch means in said third loop for delivering the fluid for said third loop to said desuperheating means for use in desuperheating the fluid in said third loop delivered to said desuperheating means from said first compressor means.

18. The apparatus of Claim 11 comprising dryer means comprising a rotatable drum for receiving fluid from said first loop flowing from said first heat exchanger means and returning the fluid to first loop; and hood means positioned adjacent to said drum;
means for delivering heated air to said hood;
said second loop comprising means for receiving heated air leaving said hood.

19. The apparatus of Claim 11 wherein each of said heat exchanger means comprises heat exchanger means of the falling film type.

20. The apparatus of Claim 19 wherein circulating means are provided for continuously delivering one of the fluids in each heat ex-changer means from the lower end of the heat exchanger means to the upper end thereof to facilitate energy transfer between the fluids introduced into the heat exchanger means.

21. The apparatus of Claim 11 wherein selected ones of said heat exchanger means further comprise means responsive to the temperature and pressure of fluid in said third loop entering said exchanger means for regulating the flow rate of said fluid introduced into the heat exchanger means.

22. A method for waste energy recovery comprising the steps of:

moving a first fluid through a first circuit along a heat transfer surface;
moving a second fluid along a first portion of said heat transfer surface to transfer heat to said first fluid;
moving a third fluid along a second portion of the heat transfer surface;
condensing said third fluid with said first fluid as the third fluid passes a second portion of said heat transfer surface;
dividing the condensed third fluid into first and second branches in said loop;
evaporating said third fluid in said first branch with said second fluid after the second fluid leaves said heat transfer surface;
thereafter evaporating said third fluid in said second branch with said second fluid;
compressing the evaporated third fluid in said second branch;
merging the compressed fluid in said second branch with the evaporated fluid in said first branch;
compressing the merged third fluid; and thereafter returning the compressed merged third fluid to said second portion of said heat transfer surface.

23. A method for waste energy recovery comprising the steps of:

moving a first fluid in a first loop along a heat transfer surface;
moving a second fluid in a second loop along said heat transfer surface to transfer heat to said first fluid;
moving a third fluid in a third loop along a second heat transfer surface;
condensing said third fluid with said first and fluid as the third fluid passes said second heat transfer surface;

dividing the condensed third fluid into first and second branches in said third loop;
evaporating said third fluid in said first branch with said second fluid after the second fluid leaves said heat transfer surface;
thereafter evaporating said third fluid in said second branch with said second fluid;
compressing the evaporated third fluid in said second branch;
merging the compressed fluid in said second branch with the evaporated fluid in said first branch;
compressing the merged third fluid; and thereafter returning the compressed merged third fluid to said second heat transfer surface.

24. The method of Claim 23 further comprising the step of utilizing a portion of the condensed third fluid leaving the second por-tion of said heat transfer to desuperheat a compressed third fluid in said first branch before it merges with the evaporated third fluid in said second branch.

25. A method for recovering waste energy from a heated fluid comprising the steps of:

a. transferring energy from the heated fluid to first and second working fluids in a sequential fashion;
b. thereafter compressing the second working fluid;
c. desuperheating the compressed second working fluid;
d. transferring the heat energy of the desuper-heated second working fluid to the first working fluid;
and e. returning the second working fluid to the influence of said heated fluid to again receive energy from said heated fluid.

26. The method of Claim 25 further comprising the steps of:
f. delivering the first working fluid to a load;
and g. utilizing at least a portion of the first working fluid leaving said load to further increase the energy of the second working fluid before the second working fluid undergoes compression.

27. The method of Claim 26 wherein step (g) further comprises the steps of:
h. compressing the second working fluid in the vapor phase; and i. thereafter desuperheating the second working fluid.

28. The method of Claim 25 further comprising the steps of:
j. separating the desuperheated second working fluid into liquid and vapor phases;
and k. using the second working fluid in the vapor phase to perform step (d).

29. The method of Claim 25 wherein step (e) further comprises the step of:
transferring the energy of the second working fluid to the first working fluid to preheat the first working fluid before the first working fluid receives energy from the heated fluid and the second working fluid, said second working fluid thereby being cooled to increase the amount of energy subsequently transferred to the second working fluid by said heated fluid.

30. Apparatus for recovering waste energy from a heated fluid comprising:

a loop for circulating a first working fluid;
heat exchanger means in said first loop for transferring energy from said first working fluid to a second working fluid.
first evaporator means in said loop for transfer-ring energy from said heated fluid to said first working fluid;
compressor means and desuperheating means in said loop for respectively compressing and desuperheating said first working fluid prior to introduction of the first working fluid into said heat exchanger means; and said heat exchanger means including means for transferring energy from said heated fluid to said first working fluid.

31. Apparatus for recovering waste energy from a heated fluid comprising:
a loop for circulating a first working fluid;
heat exchanger means in said first loop for transferring energy from said first working fluid to a second working fluid in a second loop;
first evaporator means in said first loop for transferring energy from said heated fluid to said first working fluid;
compressor means and desuperheating means in said loop for respectively compressing and desuperheating said first working fluid prior to introduction of the first working fluid into said heat exchanger means;
and said heat exchanger means including means for transferring energy from said heated fluid to said first working fluid.

32. The apparatus of Claim 31 further comprising second evapora-tor means in said loop coupled to said load means for transferring energy from the first working fluid leaving said load to said second working fluid as the second working fluid leaves said heat exchange means, and returning the second working fluid to said loop to merge with the portion of the second working fluid leaving said first evaporator means.

33. The apparatus of Claim 31 further comprising second evapora-tor means in said loop for transferring energy from said heated fluid to :;
said second working fluid;
second compressor means and second desuperheater means in said loop for sequentially compressing and desuperheating the second work-ing fluid leaving said second evaporator means; and merging means in said loop for introducing the second working fluid leaving said first desuper-heater means into said second compressor means.

34. The apparatus of Claim 33 wherein said merging means further comprises:
separator means for separating the second working fluid received by the separator means into a vapor phase to said first and second evaporator means; and means for introducing the second working fluid in the vapor phase into solid second compressor means.

35. The apparatus of Claim 31 further comprising means coupled to said separator means for diverting a portion of said second working fluid in the vapor phase to said first and second desuperheating means for mixing the second working fluid entering each desuperheating means from its associated compressor means with the second working fluid received from said introducing means for uniformly desuperheating the second working fluid received from said compressor means.

36. The apparatus of claim 35 wherein said first and second desuper-heating means each comprise mixing means for mixing the second working fluid entering each desuperheating means from its associated compressor means with the second working fluid received from said introducing means for uniformly desuperheating the second working fluid received from said compressor means.

37. The apparatus of Claim 31 further comprising means in said loop for transferring energy from said second working fluid, as the second working fluid leaves said heat exchange means, to said first working fluid prior to the first working fluid entering said heat exchange means.