DK151182C

DK151182C - EVAPORATION PROCEDURE AND APPARATUS

Info

Publication number: DK151182C
Application number: DK318283A
Authority: DK
Inventors: Heimo Vaelimaeki
Original assignee: Mkt Tehtaat Oy
Priority date: 1981-11-10
Filing date: 1983-07-11
Publication date: 1993-03-15
Also published as: FI63680B; DE3249168T1; DK318283D0; DK318283A; DE3249168C2; WO1983001579A1; SE8303898D0; DK151182B; FI63680C; SE8303898L; NL8220411A

Description

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Denne opfindelse angår en inddampningsfremgangsmåde, ved hvilken inddampningen sker under anvendelse af mindst to separate, efter hinanden følgende inddampere forbundet i serie med hensyn til den væske, der inddampes, hvorhos den i den første inddamper dannede damp skilles fra den tilbagestående væske, som føres til den anden inddamper til videre inddampning, og hvor den væske, der skal inddampes, opvarmes med damp, som i det mindste delvis består af den ved inddampningen dannede damp, og som tilføres inddamperne fra et kanalsystem, der er udstyret med mindst to blæsere, der øger dampens tryk, hvormed dampen udsættes for en trykforøgelse, før den føres til inddamperen.This invention relates to a process of evaporation in which the evaporation is carried out using at least two separate successive evaporators connected in series with respect to the liquid being evaporated, whereby the steam formed in the first evaporator is separated from the residual liquid which is fed to the the second evaporator for further evaporation, and wherein the liquid to be evaporated is heated by steam which consists, at least in part, of the steam formed by the evaporation, and which is supplied to the evaporators from a duct system equipped with at least two fans; increases the pressure of the steam, with which the steam is subjected to a pressure increase before being fed to the evaporator.

Der kendes i teknikken sådanne inddampningsfremgangsmåder, hvor den væske, der skal inddampes, føres gennem efter hinanden følgende inddamperenheder, således at inddampnings-temperaturen og faststofindholdet i væsken øges trinvis. Det er muligt som opvarmningsdamp at anvende den damp, der skilles fra den væske, der inddampes, idet tryk og temperatur i denne damp øges ved hjælp af blæsere, kompressorer eller lignende apparater.In the art, such evaporation methods are known in which the liquid to be evaporated is passed through successive evaporator units so that the evaporation temperature and the solids content of the liquid are incrementally increased. It is possible to use as steam steam the steam which is separated from the liquid which is evaporated, as the pressure and temperature in this steam is increased by means of fans, compressors or similar appliances.

Fra det svenske patentskrift nr. 55 386 kendes et apparat, af omtrent ovennævnte art, som består af vertikale varme-rør, hvori den væske, der skal inddampes, sammen med den dannede damp stiger opad og samles i et kammer, der ligger over rørene. Der er i dette apparat dog i hovedsagen tale om et enkelt inddampningstrin og ikke om et gennemført flertrinsinddampningsapparatur. Der indgår i dette anlæg en enkelt kompressor til frembringelse af tryk- og temperatur-forøgelse i dampen. Denne kompressor har seks afdelinger, hvis funktioner ikke beskrives nærmere, men disse afdelinger er sammenkoblede, og man kan således ikke regulere hver 2From the Swedish patent specification 55 386 there is known an apparatus, of the above-mentioned type, consisting of vertical heat pipes in which the liquid to be evaporated together with the steam formed rises upwards and is collected in a chamber overlying the pipes. . In this apparatus, however, this is essentially a single evaporation step and not a completed multi-stage evaporation apparatus. This plant includes a single compressor for generating pressure and temperature increase in the steam. This compressor has six compartments, the functions of which are not described in detail, but these compartments are interconnected, so you cannot control every 2

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Fra det amerikanske patentskrift nr. 1 200 996 kendes et inddampningsanlæg med et system af seriekoblede blæsere. I dette anlæg fores den damp, der dannes i en inddamper, til den i seriesystemet foregående inddamper, hvor den blandes med væsken, som skal inddampes deri. Dette anlæg er i sin konstruktion kompliceret, og reguleringen af inddampnings-processen er vanskelig.U.S. Patent No. 1,200,996 discloses an evaporation plant with a system of series-connected fans. In this system, the vapor formed in an evaporator is fed to the evaporator preceding the series system where it is mixed with the liquid to be evaporated therein. This system is complicated in its design and the regulation of the evaporation process is difficult.

De kendte fremgangsmåder af ovennævnte art har i praksis vist sig at implicere problemer på grund af den kendsgerning, at processernes effektivitet tenderer til at aftage med tiden på grund af inddampernes tilsmudsning. Da faststofindholdet af det fortykkede produkt skal være konstant, må tabet i inddampningseffektivitet kompenseres ved tillæg til blæsernes loftehøjde. Det er imidlertid en kendsgerning, at alle reguleringsorganer i forbindelse med blæserne øger disses energiforbrug, hvortil kommer, at reguleringen skal være yderst nøjagtig, idet selv en mindre ændring i den mængde væske, der fordampes, bevirker en forholdsmæssig stor ændring i koncentrationen af det fortykkede produkt. Af denne årsag er der i praksis opstået vanskeligheder ved at holde denne koncentration konstant.The known processes of the above-mentioned kind have in practice been found to imply problems due to the fact that the efficiency of the processes tends to decrease over time due to the soiling of the evaporators. Since the solids content of the thickened product must be constant, the loss in evaporation efficiency must be compensated by addition to the ceiling height of the fans. However, it is a fact that all the regulators associated with the fans increase their energy consumption, in addition to the fact that the regulation must be extremely accurate, since even a small change in the amount of liquid evaporated causes a relatively large change in the concentration of the thickened product. For this reason, in practice, difficulties have been encountered in keeping this concentration constant.

Det er formålet med denne opfindelse at frembringe en ind-dampningsfremgangsmåde, ved hvilken de nævnte problemer stort set er undgået.It is the object of this invention to provide an evaporation process in which the said problems are largely avoided.

Dette formål opnås ved en inddampningsfremgangsmåde af den indledningsvist angivne art, hvilken fremgangsmåde ifølge opfindelsen er ejendommelig ved, at den ved inddampningen dannede damp samles i kanalsystemet og ledes, eventuelt sammen med en udefra tilført tilskudsdamp, til den første blæser, som virker som hovedblæser, idet en del af den damp, der er passeret her igennem, føres til den første 3This object is achieved by an evaporation process of the type initially described, the method of the invention being characterized in that the vapor generated by the evaporation is collected in the duct system and is supplied, optionally together with an external supplementary steam, to the first blower which acts as a main blower. part of the vapor passed through it being passed to the first 3

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inddamper i serien, og en anden del til den anden blæser, der virker som hjælpeblæser, hvorfra dampen ledes til den anden inddamper i serien, og at blæserne drives uafhængigt af hinanden og i hovedsagen således, at regulering af ind-dampningen sker med hjælpeblæseren, medens hovedblæserens funktion holdes konstant.evaporator in the series, and a second portion to the second blower which acts as auxiliary blower, from which the steam is directed to the second evaporator in the series, and that the blowers are operated independently of each other and substantially so that the evaporation is controlled by the auxiliary blower, while keeping the main fan function constant.

Ved konstruktionsløsningen for opfindelsen, hvor hovedblæseren kan være væsentligt større end hjælpeblæseren, er det ikke absolut nødvendigt at regulere hovedblæseren overhovedet under processen, idet alle reguleringsforholdsregler i stedet kan være rettet mod hjælpeblæseren. Herved undgås nødvendigheden af at montere dyrt reguleringsudstyr på hovedblæseren, og der opstår ikke ekstra energiforbrug ved processen. På grund af hjælpeblæserens mindre størrelse er monteringen af reguleringsorganer på denne enhed mindre dyr, og også fordi den energimængde, der optages af hjælpeblæseren, er mindre, vil dette ikke væsentligt forøge processens totale energiforbrug selv ved ringere effektivitet, hvis dette var tilfældet. Den lille hjælpeblæser kan også reguleres temmelig nøjagtigt, således at den ønskede faststofkoncentration i det færdige, fortykkede produkt opnås nøj agtigt.In the construction solution of the invention, where the main blower can be substantially larger than the auxiliary blower, it is not absolutely necessary to regulate the main blower at all during the process, as all control measures may instead be directed to the auxiliary blower. This avoids the necessity of mounting expensive control equipment on the main fan, and no additional energy consumption arises in the process. Due to the smaller size of the auxiliary fan, the mounting of regulators on this unit is less expensive, and also because the amount of energy consumed by the auxiliary fan is smaller, this would not significantly increase the total energy consumption of the process even at poorer efficiency. The small auxiliary fan can also be adjusted fairly accurately so that the desired solids concentration in the finished thickened product is accurately obtained.

Opfindelsen angår endvidere et apparat til udøvelse af den lige beskrevne fremgangsmåde. Dette apparat omfatter på en måde, der i sig selv er kendt i teknikken, mindst to efter hinanden følgende inddampere, der er forbundet i serie med hensyn til den væske, der inddampes,hvorhos inddamperne er udstyret med kanaler til indføring af væsken til den første inddamper, transport af den tilbagestående væske til den anden inddamper og fjernelse af slutproduktet samt med kanaler til fjernelse af den i den første henholdsvis den anden inddamper dannede damp, og et kanalsystem, gennem hvilket opvarmningsdamp, som i det mindste består af den ved 4The invention further relates to an apparatus for carrying out the method just described. This apparatus comprises, in a manner known per se in the art, at least two successive evaporators connected in series with respect to the liquid being evaporated, the evaporators being provided with channels for introducing the liquid into the first evaporator, transport of the residual liquid to the second evaporator and removal of the final product, and with channels for removing the vapor formed in the first and second evaporators, respectively, and a duct system through which a heating vapor at least consisting of it at 4

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inddampningen dannede damp, transporteres til inddamperne, og som er forsynet med mindst to blæsere, der øger damptrykket. Apparatet er ejendommeligt ved, at kanalerne til fjernelse af dampen fra inddamperne indgår i kanalsystemet til tilførsel af opvarmningsdampen og er koblet til den første af blæserne, som udgør en hovedblæser, der ved hjælp af kanaler er forbundet dels til den første inddamper i serien og dels til den anden blæser, der virker som hjælpeblæser, og at hjælpeblæseren ved hjælp af en kanal er forbundet med den anden inddamper i serien, og at blæserne med hensyn til deres funktion er selvstændige, så inddampningen 1 hovedsagen kan reguleres med hjælpeblæseren, mens hovedblæserens funktion forbliver uændret.the vapor generated steam is transported to the evaporators and is provided with at least two blowers which increase the vapor pressure. The apparatus is characterized in that the channels for removing the steam from the evaporators are included in the duct system for supplying the heating steam and are coupled to the first of the blowers which constitute a main blower connected by means of ducts partly to the first evaporator in the series and partly to the second blower which acts as auxiliary blower, and that the auxiliary blower is connected by means of a second evaporator in the series and that the blowers in respect of their function are independent, so that the evaporation 1 can be controlled essentially with the auxiliary blower, while the function of the main blower remains unchanged.

Opfindelsen beskrives i det følgende mere detaljeret ved hjælp af et eksempel med henvisning til tegningen, der viser et inddampningsapparat ifølge opfindelsen.The invention will now be described in more detail by way of example with reference to the drawing which shows an evaporator according to the invention.

Det apparat, der er vist på tegningen, omfatter to efter hinanden følgende inddampere 1 og 2 forbundet i serie, og gennem hvilke den væske, der skal inddampes, føres, idet den passerer gennem ledningerne 3, 4 og 5. Inddampningen sker ved hjælp af damp, idet denne damp i det væsentlige er fremstillet af den damp, der skilles fra den væske, der skal inddampes i inddamperne 1 og 2. Denne damp, der opnås fra den væske, der inddampes, fjernes fra inddamperne 1 og 2 ind i kanalerne 6 og 7, og føres yderligere gennem kanalerne 8, 9 og 10 som opvarmningsdamp tilbage til inddamperne. Til kanalen 7 er forbundet kanalen 11, gennem hvilken det er muligt at indføre ekstern damp i apparatet for at opretholde den termiske ligevægt.The apparatus shown in the drawing comprises two successive evaporators 1 and 2 connected in series and through which the liquid to be evaporated is passed as it passes through conduits 3, 4 and 5. Evaporation is effected by means of vapor, said vapor being substantially made of the vapor which is separated from the liquid to be evaporated in evaporators 1 and 2. This vapor obtained from the liquid being evaporated is removed from vaporizers 1 and 2 into the ducts 6 and 7, and is further passed through channels 8, 9 and 10 as heating steam back to the evaporators. Connected to the duct 7 is the duct 11 through which it is possible to introduce external steam into the apparatus to maintain the thermal equilibrium.

Kanaisystemet 6-11 er forsynet med to blæsere 12 og 13, ved hjælp af hvilke opvarmningsdampens tryk og temperatur øges i fornoden grad. Blæseren 12 i kanalen 8 virker som hoved- 5The duct system 6-11 is provided with two fans 12 and 13, by means of which the pressure and temperature of the heating steam increase as required. The fan 12 in the channel 8 acts as the main 5

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blæser, gennem hvilken al den opvarmningsdamp, der anvendes mod inddampningen, passerer. Hovedparten af denne damp fores, for at virke som opvarmningsdamp, til den forste inddamper 1 i serien, og resten fores gennem kanalen 9 til blæseren 13, der virker som hjælpeblæser, og derfra videre gennem kanalen 10 for at blive opvarmningsdamp til den sidste inddamper 2 i serien. Det kondensat, der dannes af opvarmningsdampen, fjernes fra inddamperne 1 og 2 i ledningerne 14 og 15.blower through which all the heating steam used against the evaporation passes. The majority of this steam is fed, to act as a heating steam, to the first evaporator 1 in the series, and the remainder is fed through the duct 9 to the fan 13 which acts as auxiliary fan, and thence through the duct 10 to become the heating steam to the last evaporator 2. in the series. The condensate formed by the heating steam is removed from evaporators 1 and 2 in lines 14 and 15.

I det viste apparat kan effektværdien for hjælpeblæseren 13 være af størrelsesordenen fra .1/10 til 1/5 af værdien af hovedblæseren 12. Hovedblæseren 12 er indrettet til at arbejde under optimale betingelser og reguleres ikke under inddampningsprocessen, af hvilken grund den ikke behøver at være forsynet med energiforbrugende reguleringsmidler. Det fald i inddampningseffektiviteten, der sker i løbet af processen på grund af tilsmudsning af inddamperne 1 og 2, kompenseres udelukkende ved regulering af hjælpeblæseren 13, og til dette formål er hjælpeblæseren forsynet med en inverter, ledefinnekontrol eller lignende løftehøjderegule-rende organer. Idet hovedparten af inddampningen sker i den første inddamper 1 i serien, og kun en mindre del af opvarmningsdampen passerer gennem hjælpeblæseren 13, har reguleringsorganerne for hjælpeblæseren ingen væsentlig indflydelse på processens totale energiforbrug. Kontrollen af hjælpeblæseren 13 kan i tilfælde med høje inddampningsfor-hold være baseret på måling af slutproduktets tæthed, og som et resultat af styringens store nøjagtighed opnås højere faststofkoncentrationer i slutproduktet end før.In the apparatus shown, the power value of the auxiliary blower 13 may be of the order of .1 / 10 to 1/5 of the value of the main blower 12. The main blower 12 is adapted to operate under optimal conditions and is not controlled during the evaporation process, for which reason it does not have to be provided with energy-consuming regulators. The decrease in evaporation efficiency that occurs during the process due to fouling of evaporators 1 and 2 is compensated solely by regulation of the auxiliary fan 13, and for this purpose the auxiliary fan is provided with an inverter, guide fin control or similar lifting height regulating means. Since most of the evaporation takes place in the first evaporator 1 in the series, and only a minor part of the heating vapor passes through the auxiliary fan 13, the auxiliary fan control means have no significant influence on the total energy consumption of the process. The control of the auxiliary fan 13 can, in cases with high evaporation conditions, be based on the measurement of the density of the final product, and as a result of the high accuracy of the control, higher solids concentrations in the final product are obtained than before.

Blandt anvendelserne for opfindelsen kan for eksempel nævnes forbehandlingen før tørreprocessen af valle, der anvendes ved fremstilling af vallepulver. Tørringen kan for eksempel ske i et spray-tørringsanlæg. Ved sådan en forbe- 6Among the uses of the invention, for example, may be mentioned the pre-treatment before the drying process of whey used in the manufacture of whey powder. The drying can be done, for example, in a spray-drying system. By such a preparation 6

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handling øges faststofindholdet i vallen fra 6 til 60%, idet der anvendes for eksempel to efter hinanden følgende inddampere, af hvilke den første øger faststofindholdet til cirka 20%. Ved en sådan proces kan hovedblæseren have en effektværdi omkring seks gange den for hjælpeblæseren, og processen kan være således dimensioneret, at den nødvendige eksterne opvarmningsdamp højest er få procent af den totale mængde opvarmningsdamp.For example, the solid content of the whey is increased from 6 to 60%, using, for example, two successive evaporators, the first of which increases the solids content to about 20%. In such a process, the main blower may have a power value about six times that of the auxiliary blower, and the process may be dimensioned such that the required external heating steam is at most a few percent of the total amount of heating steam.

Claims

An evaporative process in which the evaporation is carried out using at least two separate successive evaporators (1, 2) connected in series with respect to the liquid being evaporated, whereby the steam formed in the first evaporator is separated from the residual liquid, which is fed to the second evaporator for further evaporation, and wherein the liquid to be evaporated is heated by steam which is at least partially formed by the steam formed by the evaporation and which is supplied to the evaporators from a duct system (6-11) which is equipped with at least two blowers (12, 13) which increase the pressure of the steam, by which the steam is subjected to a pressure increase before being fed to the evaporator, characterized in that the steam formed by the evaporation is collected in the duct system (6, 7) and conducted, optionally, together with an outside supply steam, to the first blower (12) which acts as a main blower (12), a portion of the steam passed through it being fed to the first evaporator (1) ice and a second portion to the second blower (13) acting as auxiliary blower from which the steam is directed to the second evaporator in the series, and the blowers are operated independently of each other and substantially so that the evaporation is controlled by the auxiliary blower, while the main blower function is maintained constantly.

Process according to claim 1, characterized in that the solids content of the final product is kept constant during the evaporation by controlling the lift height of the auxiliary fan (13).

Apparatus for carrying out a process according to claim 1 or 2, comprising at least two successive evaporators (1, 2) connected in series with respect to the liquid being evaporated, the evaporators being 3. equipped with channels (3, 4, 5) for introducing the liquid to the first evaporator, transporting the residual liquid to the second evaporator and removing the final product, and with channels (6, 7) for removing it in the first and the second respectively. evaporator generated steam and a duct system (6-11) through which heating steam, at least consisting of the steam formed during evaporation, is conveyed to the evaporators and provided with at least two fans (12, 13) which increase the vapor pressure , characterized in that the channels (6, 7) for removing the steam from the evaporators (1, 2) are included in the duct system (6-11) for supplying the heating steam and are coupled to the first of the blowers which constitutes a main blower (12) , who knows h channel channels (8, 9) are connected partly to the first evaporator (1) in the series and partly to the second fan (13) which acts as an auxiliary fan and that the auxiliary fan is connected by means of a channel (10) the second evaporator (2) in the series, and that the fans in respect of their function are independent, so that the evaporation in the main can be regulated by the auxiliary fan, while the function of the main fan remains unchanged.

Apparatus according to claim 3, characterized in that the auxiliary fan (13) is provided with an inverter, control fin or similar means for controlling the fan lift height.