FI65376C - FOERFARANDE FOER DESTILLATION AV VAETSKOR OCH ANLAEGGNING FOERGENOMFOERANDE AV FOERFARANDET - Google Patents

Description

RIGHT Γβΐ «i ^ ANNOUNCEMENT PUBLICATION / r 7π / ήΒΓα lBJ 01) utlAggningsskaift ODO / 0 1¾¾ c (45) raU.UL uyö ^ tty 10 03 1934 ^ ^ (51) Kv.lto / IntCl / * B ΟΊ D 3/00 (21) Pttenttlhtkemu * - Pitenuru6kning 7Ö2784 (22) H »k« ml »cloud - Ansöknlngsdag 12.09-78 ^ ® ^ (23) Alkupllvt - Glltlghetsdtg 12.09.78 (41) Tullut kiikikuksi - Bllvlt offemllg j_3.03.7

National Board of Patents and Registration · .... ........,,. .....

_ 1 (44) NUtavIktlptnon | t Date of issue. -

Patent · och reglstentyreleen Anaeiun uthgd och uti.tkrtfun puMlcmd 31.01.8k (32) (33) (31) Privilege claimed — Begird prlorttet 12.09.77

Sweden si-Sverige (SE) 7710213-5 (71) (72) Risto Saari, Harjula, 02l * U0 Luoma, Finland-Finland (FI) (7 * 0 Forssan & Salomaa Oy (5 ^) Method for distilling liquids and equipment method of implementation - Förfarande för destination av vätskor och anläggning för genomförande av förfarandet

The invention relates to a process for distilling liquids in at least two successive distillation units operating at different temperature levels, in which process the liquid to be distilled in each of said distillation units is evaporated and the steam formed is condensed to a distillate the liquid is vaporized and accordingly are condensed in at least two distillation step and wherein each of the distillation unit in said distilled in a distillation step, the liquid is passed last distillation step of the evaporator of the next distillation stage evaporator, where the prevailing pressure is almepi than the pressure prevailing in the preceding distillation stage the evaporator, wherein said höyristimen distil the liquid flowing through the cooled as it flows from the previous distillation step to the next distillation stage .

The invention also relates to a device for carrying out the method according to the invention.

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Today's commonly used, special! The distillation methods developed for seawater distillation are the so-called vertical tube evaporation and multi-stage expansion distillation. Each of these previously known methods has its own pros and cons. The disadvantages of these known methods are highlighted when trying to use distillation, for example, to concentrate various industrial wastewaters.

In vertical pipe evaporation, the liquid evaporates on the inner surface of the heat exchange pipes. This causes fouling of the heat exchange surfaces, which is the most important disadvantage of this method.

When multi-stage expansion distillation is used in the concentration of solutions, the disadvantage is that the same concentrated solution has to be recycled over the entire temperature range of the distillation plant, whereby the boiling point of the liquid to be distilled and the viscosity substantially impair the operation of the distillation plant. In addition, when applying this method, it is necessary to build a distillation plant in a very multi-stage, if the most expensive component of the distillation plant, the condenser tube, is to be kept of a reasonable size. This is because the smaller the drop in temperature of the evaporating liquid per distillation step, the greater the temperature difference between the condensing steam and the coolant.

It is an object of the invention to provide a process for distilling liquids which eliminates the disadvantages of the previously known processes. It is a more detailed object of the invention to provide a method for distilling liquids, in which method the change in the temperature of the liquid in one distillation step can be influenced within certain limits without having to unnecessarily increase the number of distillation lies.

Yet another object of the invention is to provide a method for distilling liquids, by means of which liquids of different concentrations can be treated at different temperatures, whereby the increase in the boiling point and the increase in viscosity do not have a complete effect over the entire temperature range. It is a further object of the invention to provide a method for distilling liquids, in which method the evaporation of the liquid to be distilled can be carried out from a free liquid space and thus prevent fouling of the heat transfer surfaces.

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aims of the invention are achieved by a method which is mainly characterized in that the cooled distilled in a liquid said derived from the previous higher temperature level, operating a distillation condensers a coolant, and that each of the distillation mentioned the distillation condensers is passed a coolant working in the following at a lower temperature distillation of the steam vaporized liquid flowing through, wherein said lauhduttumien flowing through the cooling fluid heats up as it flows from the distillation step to the previous distillation step, and that said heated coolant is returned to the evaporators of said lower temperature distillation unit.

It is also an object of the invention to provide an apparatus for carrying out the method according to the invention. The device according to the invention is in turn characterized by the features according to claims 5-8.

The invention will be explained in detail with reference to the principle solution of the invention shown in the figure of the accompanying drawing, to which, however, the invention is not intended to be exclusively limited.

The distillation process shown in the figure of the accompanying drawing consists of several successive distillation units, i.e. modules 1,11,111 ... N. According to the invention, each module has several distillation steps V., V _ ... V. Each l / m distillation stage includes an evaporator and a condenser which are connected to each other so that the steam generated in the evaporator can flow into the condenser and condense there into a distillate. Thus, for example, the evaporator 11 ^ and the condenser 14 ^ of the module 1 belong to the first distillation stage V ^, the evaporator 12 ^ and the condenser 15 ^ to the second distillation stage, and the evaporator 13 ^ and the condenser 16j belong to the last distillation stage Vm · the evaporators 11 ^, 12 ^ that the liquid to be distilled may flow from the evaporator II to the evaporator 12 and further to the subsequent evaporators, but the flow of steam from one evaporator to another is prevented.

The liquid to be distilled flows in the module 1 to the evaporator 11 ^, where part of the liquid evaporates and the steam condenses in the condenser 14 ^. The liquid to be distilled continues to flow to the evaporator 12 ^, where a lower pressure prevails than in the evaporator 11 ^, and again part of the liquid to be distilled evaporates. Upon evaporation, the liquid to be distilled cools and the cooled liquid leaves the last evaporator 13 ^ by means of a pump 17 4 65376 to a heater 10, where the liquid to be distilled is heated by external energy and from which it returns heated to the evaporator 11.

The liquid flowing through the condensers 16, 15 and 14 of the module 1 heats up when it receives the heat of vaporization of the condensable steam. The heated liquid flows from the condenser 14 to the pipe 22 to the first evaporator 11 of the module 11, where a lower pressure and temperature prevail than in the first evaporator 11 of the module 1. The liquid evaporates in the evaporators 11, 12 and 13 of the module 11, whereby the liquid cools and flows through the pipe 20, the pump 18 and the pipe 21 to the condensers 16, 15 and 14p of the module 1, which thus act as heaters for the module 11.

The pathing process proceeds similarly from module to module until the thermal energy initially supplied to the heater 10 is transferred through the condensers 16N> 15N and 14N of the last module N to the coolant flowing through the pipe 26 and leaving the system via the pipe 27.

The liquid to be distilled can be fed into the system, for example, to the last module N up to the pipe 29. In module N, part of the liquid to be distilled is distilled and part is fed to the following modules. The feed pump 24 "feeds the liquid to be distilled down the pipe 25" into the liquid circuit of the module 111, from which again part of the liquid to be distilled passes through the pipe 23 ', the pump 24' and the pipe 25 'into the liquid circuit of the module 11. From the liquid circuit of the module 11, a part of the liquid to be distilled passes through the pump 24 and the pipe 25 to the liquid circuit of the module 1. The final concentrate is removed from the liquid circuit of module 1 up to the pipe 30. Depending on the temperature, the initial liquid to be distilled can be fed to any module and the final concentrate can be removed, depending on its properties, from any module. The distillate can be removed from each module 1.11 ... N separately up to the tubes 31 ^, 31 ^ ... 31 ^ or from the module N operating at the temperature level by collecting all the distillate into the module N and removing the distillate from there down the tube 31 ^.

In the method according to the invention, the concentration of the flowing liquid in each module 1.11 ... N can be adjusted to deviate from the concentration of the flowing liquid in the other modules, which has a considerable advantage, especially when concentrating solutions, such as industrial wastewater. In this case, the increase in the boiling point of the liquid essentially affects only a part of the temperature range. In addition, the additives required to prevent corrosion and scale can be adapted to each module 5 65376 separately or can be allowed to automatically concentrate in those liquid circuits where the liquid concentration is highest.

In the method according to the invention and in the device for carrying it out, the condensers can be constructed substantially below the free liquid surfaces of the evaporators using horizontal tubes, whereby the liquid does not tend to evaporate as it flows in the condensers. The entire distillery can be built from similar modules, which has a significant impact on the design and manufacturing costs of the distillery.

If the difference between the highest and lowest temperature of the distillation process - ^ is denoted by cf ^ T, the boiling point rise S 'T and the drop in liquid temperature as it flows through all the distillation stages of one module <f T, is the average logarithmic temperature difference between steam and condenser: £ Vm

T - R

f «r0T- £,, ί'τ- ^ N rj

lio T ‘fcl i’ T - «TT - N ^ J

w This temperature difference A T substantially affects the size of the most expensive components of the distillation, i.e. the condensers. From the above expression, it can be stated that this temperature difference Δ T depends on the decrease in the temperature of the liquid to be distilled per distillation step, i.e. the ratio cf T / m, as in multi-stage distillation. The essential difference is that in a multi-stage expansion distillation, when the quantity cf QT is determined, the ratio (f T / m can only be affected by increasing the number of distillation steps. In the process according to the invention, the ratio T / m can be influenced by changing the 1.11 ... N liquid flow rate and condenser dimensioning.

The following comparison illustrates the advantages achieved by the invention. If 6 65376 & qT = 60 ° C, £ 'T * 1 ° C and the efficiency of multi-stage expansion distillation, i.e.

the ratio of the distilled water produced to the amount of westernization steam used is 8, a logarithmic temperature difference is obtained for a 48-stage multi-stage expansion distillation plant of 5.09 ° C. If the other output values are the same, a logarithmic temperature difference of 5.61 ° C is obtained in the method according to the invention when N * 8, ra * 3 and * 3 ° C. The corresponding distillation capacity according to the invention can thus be built with a 10% smaller condenser and a total of only 24 distillation stages, i.e. half of the distillation stages of the conventional distillation process.

From the temperature difference expression, it can be further stated that in different distillation units the elevations of the boiling point of the liquid may differ and affect the mean logarithmic temperature difference Δ T as a sum, with the boiling point increase only affecting its own boiling point and not the whole process temperature.

Due to their internal structure and mutual arrangement, the distillation units can be arranged in such a way that the liquid to be distilled in the condensers of a particular distillation unit is lower than the free surface of the liquid to be distilled in the evaporators of the next distillation unit. Of course, all the distillation units of the distillery can be constructed as mentioned above. In this case, the advantage is obtained that the liquid does not tend to evaporate as the coolant flows in the condensers, which could substantially cause fouling of the heat exchange surfaces and deterioration of the heat exchange. This is known to be an essential disadvantage of the commonly used vertical tube evaporation, especially when concentrating solutions, because in vertical tube evaporation the evaporation takes place precisely on the surfaces of the heat exchange tubes. In the method according to the invention, on the other hand, the inner surfaces of the heat exchange tubes can be kept constantly clean, for example by placing a suitable number of cleaning balls in each closed circuit of the liquid.

It is advantageous to assemble a distillery consisting of several distillation units from similar distillation units, which contributes to lowering the construction costs of the distillery.

Only the basic solution of the invention has been described above, and it will be clear to a person skilled in the art that the details of the invention can vary widely within the scope of the inventive idea set out in the appended claims.

Claims (8)

1. Process for the destination of liquids in Itminstone two consecutive distillation units (1.11, ... N) operating on different temperature (T ^, T₂, ... TN), wherein and one of said distillation units (1,11, ... N) of the distillation liquid is fed and the formed Ingen is condensed into distilled 1 heat exchange with flowing liquid from the following distillation unit, operating at a lower temperature level, at which process the liquid to be distilled is at least one. of said distillation units (1,11, ... N), respectively, it is condensed in At least two distillation stages (V 1 ..N) said distillation step (V ^, ^, ... V) from the extender in the preceding distillation step to the extender in the following distillation step, where the exerting pressure Mr is lower than the exerting pressure in the extender in said preceding distillation step. With said extender, the distillation liquid is cooled by flowing from the preceding distillation step to the following distillation step, whereby said cooled distillation liquid is led to the condensers in the foregoing, at a higher temperature level! operating distillation unit as coolant, and adding the capacitors in each distillation unit's said distillation stage as cooling liquid through the extensions in the following, at a lower temperature level! the working liquid distillation unit to be fed, the cooling liquid flowing through said capacitors being heated by flowing from a distillation step to the preceding distillation step, and said heated cooling liquid being returned to the extensions in said temperature. working distillation unit. 2. A process according to claim 1, characterized in that the liquid to be distilled is fed into one of said distillation units (1,11, ... N), from which the distillation unit is distilled liquid to the other distillation units, and that the concentrated liquid theater of the distillation liquid is removed from any distillation unit other than that into which the distillation liquid is fed. Process according to claim 1 or 2, characterized in that the distillate formed by the distillation liquid is collected in the distillate.