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66:
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which in 2008 had become increasingly valuable. The water quality of evaporators is four times better which is needed for the drum boilers. The evaporators, when coupled with standard drum boilers, produce steam which is more "reliable, less costly to operate, and less water-intensive." By 2008 about
604:
of the salt water we wish to evaporate (8 K for a saturated salt solution), this leaves a temperature difference of less than 8 K at the heat exchanger. A small ∆T leads to slow heat transfer, meaning that we will need a very large heating surface to transfer the required heat. Axial-flow and Roots
401:
The actual energy input will be greater than the theoretical value and will depend on the efficiency of the system, which is usually between 30% and 60%. For example, suppose the theoretical energy input is 300 kJ and the efficiency is 30%. The actual energy input would be 300 x 100/30 = 1,000 kJ.
718:
solution at 360 g/L has a boiling point elevation of about 7 K. This boiling point elevation is a challenge for vapor-compression evaporation in that it increases the pressure ratio that the steam compressor must attain to effect vaporization. Since boiling point elevation determines the pressure
617:- or more), the motive steam consumption will be in the range of 2 kg per kg of suction vapors. A higher compression ratio means a smaller heat exchanger, and a reduced investment cost. Moreover, a compressor is an expensive machine, while an ejector is much simpler and cheap.
266:
temperature, the same vapor can serve as the heating medium for its "mother" liquid or solution being concentrated, from which the vapor was generated to begin with. If no compression was provided, the vapor would be at the same temperature as the boiling liquid/solution, and no
701:
For economic reasons evaporators are seldom operated on low-TDS water sources. Those applications are filled by reverse osmosis. The already brackish water which enters a typical evaporator is concentrated further. The increased dissolved solids act to increase the
532:
of delivery pressure vs. suction pressure. In principle, the higher the compression ratio and the lower the motive ratio the higher will be the specific motive steam consumption, i. e. the less efficient the energy balance.
751:
in which all the water was recycled and only solids were discharged off site. This new evaporative technology began to replace older water treatment techniques employed by SAGD facilities which involved the use of warm
608:
Thermocompression evaporators may reach higher compression ratios - at a cost. A compression ratio of 2 is possible (and sometimes more) but unless the motive steam is at a reasonably high pressure (say, 16
569:
An MVR unit will be preferable for a large unit, thanks to the reduced energy consumption. The largest single body MVR evaporator built (1968, by
Whiting Co., later Swenson Evaporator Co., Harvey, Ill. in
585:, evaporating approximately 400 metric tons per hour of water, featuring an axial-flow compressor (Brown Boveri, later ABB). This unit was transformed around 1990 to become the first effect of a
621:
As a conclusion, MVR machines are used in large, energy-efficient units, while thermocompression units tend to limit their use to small units, where energy consumption is not a big issue.
596:), the condensation pressure after compression will be 0.101 x 1.8 = 0.1818 . At this pressure, the condensation temperature of the water vapor at the heat exchanger will be 390
186:
362:
501:
645:
that would otherwise be lost if the vapor, rather than the condensate, was the final product; therefore, this method of evaporation is very energy efficient. The
83:
38:
592:
The compression ratio in a MVR unit does not usually exceed 1.8. At a compression ratio of 1.8, if the evaporation is performed at atmospheric pressure (0.101
799:
462:), at a pressure higher than those of both the inlet and the outlet vapors. The quantity of compressed vapors is therefore higher than the inlet :
629:
The efficiency and feasibility of this process depends on the efficiency of the compressing device (e.g., blower, compressor or steam ejector) and the
520:, due to the possible excess of steam necessary for the compression if compared with the steam required to evaporate the solution. The quantity Q
314:
In this case the energy input to the system lies in the pumping energy of the compressor. The theoretical energy consumption will be equal to
739:'s RCC Thermal Products conceived an evaporator technology called falling film or mechanical vapor compression evaporation. In 1999 and 2002
130:
781:
85 per cent of SAGD facilities in the
Alberta oil sands had adopted evaporative technology. "SAGD, unlike other thermal processes such as
694:, vapor compression chiefly differs from these thanks to its ability to make clean water from saturated or even crystallizing brines with
102:
686:. This results in a drinkable water, if the other sanitary requirements are fulfilled. While this cannot compete in the marketplace with
674:
crystallizer, for example, a typical analysis of the resulting condensate shows a typical content of residual salt not higher than 50
44:
109:
794:
262:, and thus, increase the pressure of the vapor produced. Since the pressure increase of the vapor also generates an increase in the
222:
204:
149:
52:
278:. If compression is performed by a mechanically driven compressor or blower, this evaporation process is usually referred to as
804:
732:
698:(TDS) up to 650 g/L. The other two technologies can make clean water from sources no higher in TDS than approximately 35 g/L.
116:
809:
782:
87:
441:
if compared to the theoretical pressure/temperature equilibrium. For this reason, the vast majority of MVR units feature a
773:
98:
637:
contacting the condensing vapor and the boiling "mother" solution/liquid. Theoretically, if the resulting condensate is
872:
642:
586:
422:
76:
887:
630:
565:
These two compression-type evaporators have different fields of application, although they do sometimes overlap.
517:
882:
877:
736:
417:
The compressor is necessarily the core of the unit. Compressors used for this application are usually of the
601:
430:
744:
545:, exhaustively described in the relevant page. The size of the other pieces of equipment, such as the main
123:
695:
679:
418:
235:
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434:
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are the total heat content of unit mass of vapors, respectively upstream and downstream the compressor.
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516:
is the motive steam quantity. For this reason, a thermocompression evaporator often features a vapor
728:
659:
317:
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529:
465:
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282:(mechanical vapor recompression). In case of compression performed by high pressure motive
715:
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259:
251:
433:. Very large units (evaporation capacity 100 metric tons per hour or more) sometimes use
649:
process may be solely driven by the mechanical work provided by the compressing device.
753:
683:
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with a TDS of approximately 30 g/L exhibits a boiling point elevation of less than 1
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ratio in the compressor, it is the main overall factor in operating costs.
707:
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747:(ZLD) systems using a combination of the new evaporative technology and
743:'s MacKay River facility was the first to install 1999 and 2002 GE SAGD
769:
735:(SAGD) method. In the late 1990s former nuclear engineer Bill Heins of
589:. MVR evaporators with 10 tons or more evaporating capacity are common.
838:"Watershed moment: SAGD operators embrace new water treatment options"
776:(OTSG) traditionally used for steam production. OTSG generally ran on
757:
711:
597:
458:
The energy input is here given by the energy of a quantity of steam (
524:
of motive steam per unit suction quantity is a function of both the
575:
391:
283:
234:
671:
614:
670:, can make reasonably clean water from any water source. In a
593:
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59:
18:
541:
The heart of any thermocompression evaporator is clearly the
405:
In a large unit, the compression power is between 35 and 45
406:
395:
387:
772:. The vapor-compression evaporation process replaced the
605:
compressor may reach slightly higher compression ratios.
182:
727:
The technology used today to extract bitumen from the
557:
for details), is governed by the evaporation process.
528:
of motive steam pressure vs. suction pressure and the
371:
Q is the mass of vapors passing through the compressor
468:
445:
between the compressor and the main heat exchanger.
320:
239:
Vapor compression distiller made by BRAM-COR (Italy)
177:
may be too technical for most readers to understand
90:. Unsourced material may be challenged and removed.
495:
356:
641:, this process could allow full recovery of the
831:
829:
827:
825:
785:(CSS), requires 100 per cent quality steam."
437:. The compression work will deliver the steam
8:
508:is the steam quantity at ejector delivery, Q
800:Slingshot (water vapor distillation system)
53:Learn how and when to remove these messages
666:A vapor-compression evaporator, like most
390:units, these are respectively measured in
467:
368:E is the total theoretical pumping energy
319:
223:Learn how and when to remove this message
205:Learn how and when to remove this message
189:, without removing the technical details.
150:Learn how and when to remove this message
821:
409:per metric ton of compressed vapors.
187:make it understandable to non-experts
7:
276:vapor compression distillation (VCD)
88:adding citations to reliable sources
14:
795:Cristiani compressed steam system
34:This article has multiple issues.
706:well beyond that of pure water.
429:, similar to the (much smaller)
289:, the process is usually called
166:
64:
23:
836:Smith, Maurice (October 2008),
805:Vapor-compression refrigeration
733:steam-assisted gravity drainage
723:Steam-assisted gravity drainage
99:"Vapor-compression evaporation"
75:needs additional citations for
42:or discuss these issues on the
810:Vapor-compression desalination
351:
333:
1:
774:once-through steam generators
413:Equipment for MVR evaporators
244:Vapor-compression evaporation
274:It is also sometimes called
643:latent heat of vaporization
537:Thermocompression equipment
357:{\displaystyle E=Q*(H2-H1)}
904:
600:. Taking into account the
587:multiple effect evaporator
258:or jet ejector is used to
631:heat transfer coefficient
783:cyclic steam stimulation
737:General Electric Company
658:Clean water production (
512:at ejector suction and Q
496:{\displaystyle Qd=Qs+Qm}
731:is the water-intensive
602:boiling point elevation
431:Roots type supercharger
696:total dissolved solids
680:electrical conductance
497:
435:Axial-flow compressors
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764:and weak acid cation
745:zero-liquid discharge
682:, not higher than 10
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423:positive displacement
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84:improve this article
749:crystallizer system
729:Athabasca oil sands
660:Water for injection
873:Chemical processes
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425:units such as the
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271:could take place.
250:method by which a
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16:Evaporation method
530:compression ratio
449:Thermocompression
299:ejectocompression
295:steam compression
291:thermocompression
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845:, retrieved
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766:ion exchange
741:Petro-Canada
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583:crystallizer
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553:, etc. (see
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526:motive ratio
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460:motive steam
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454:Energy input
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310:Energy input
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264:condensation
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195:January 2015
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82:Please help
77:verification
74:
50:
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36:Please help
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868:Evaporators
847:11 December
778:natural gas
668:evaporators
647:evaporation
572:Cirò Marina
439:superheated
419:centrifugal
398:and kJ/kg.
305:MVR process
248:evaporation
140:August 2016
862:Categories
816:References
756:to remove
625:Efficiency
561:Comparison
555:evaporator
551:vapor head
256:compressor
110:newspapers
39:improve it
762:magnesium
653:Some uses
639:subcooled
518:condenser
421:type, or
343:−
331:∗
45:talk page
789:See also
708:Seawater
613:g - 250
578:) was a
364:, where
287:ejectors
260:compress
770:calcium
504:Where Q
246:is the
181:Please
124:scholar
758:silica
549:, the
252:blower
126:
119:
112:
105:
97:
684:μS/cm
576:Italy
284:steam
131:JSTOR
117:books
849:2014
760:and
672:salt
615:psig
580:salt
103:news
690:or
676:ppm
611:bar
594:MPa
386:In
378:, H
297:or
280:MVR
185:to
86:by
864::
840:,
824:^
574:,
407:kW
396:kg
394:,
392:kJ
388:SI
301:.
293:,
254:,
48:.
712:K
662:)
598:K
522:m
514:m
510:s
506:d
491:m
488:Q
485:+
482:s
479:Q
476:=
473:d
470:Q
380:2
376:1
374:H
352:)
349:1
346:H
340:2
337:H
334:(
328:Q
325:=
322:E
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220:(
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202:(
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193:(
179:.
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147:(
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138:(
128:·
121:·
114:·
107:·
80:.
55:)
51:(
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
