DE1119228B - Device for evaporating solutions that tend to form crusts - Google Patents

Description

The invention relates to a device for evaporation of solutions with a tendency to crust formation, whereby these solutions are carried out in several stages Schiagen heaters are heated and evaporated.

Numerous devices for evaporating crust-forming solutions are already known. So is known, for example (German Patent 393 408), the solutions to be evaporated in pipes while the pipes are heated with steam from the outside. However, such devices are unsuitable for grid-forming solutions because frequent cleaning of the pipes is required cannot be carried out without interrupting operations.

It is also known (German Patent 569 860), in conventional, multi-stage evaporators the first stage with live steam or exhaust steam and the following stages with the vapors of each previous stage to heat. Since with the usual evaporators, however, the solutions within are guided by pipes, these devices must often be switched off and overhauled will.

It is also common practice (German Patent 445 707, British Patent 252 505 and USA.-Patent 1390677), for multi-stage evaporators To increase the heating surfaces from level to level, however, this measure alone Crust-forming solutions cannot yet be evaporated rationally unless very specific instructions are given for temperature, pressures, type of exhaust and the like. These well-known plants also have features such as: B. Steam jet injectors in heating circuits (USA.-Patent 1390 677) or standing pipes for the solutions (British Patent 252 505) by the an efficient way of working because of the complicated structure or because of the numerous required repair work is prevented.

Furthermore, a system is also known (German patent specification 906 691), which has a small temperature difference should work between the vapor temperature and the heating fluid, but it is this known device to at least five-stage systems, in which only the system costs call a rational operation into question.

According to the invention, a device is now proposed with which one in particularly economical Way to crust-forming liquids can evaporate, with this device can be set up with simple means and requires little maintenance, even though it is on

Device for evaporation
of solutions with a tendency to crust formation

Applicant:
CH Boehringer Sohn, Ingelheim / Rhein

Dipl.-Ing. Hans-Eberhard Gottwald,

Ingelheim / Rhine,
has been named as the inventor

Economic efficiency is superior to all known facilities of this type.

This 2SeI is achieved according to the invention in that the device is designed in two stages is, wherein the coil heater of the second stage in a known manner with the vapors of the first Stage is heated and the heating surface of the coil heater of the second stage is the 1,3- to 2.0 times the heating area of the coil heater of the first stage and the treated solution and the heating means of the second stage by means of a per se known barometric exhaust device subtracted from.

The features of the invention, which are individually known, are all in an effective context, and the claimed combination cannot be said to be obvious to a person skilled in the art will. So it is surprising to use snake radiators for evaporation of crust-forming solutions use when there is only slight temperature difference between the tubes and the one to be evaporated Solution to be sustained, as such snake radiators are usually only applied if a very rapid evaporation is to take place and therefore large temperature differences are required (German patent 747576). In addition, this is an economical operation Device only possible if a certain heating surface ratio is maintained within relatively narrow limits. Since the flow resistance of snake radiators is proportionate is high and the vapors necessarily with a low pressure difference through these radiators are conducted, the usual exhaust devices for evaporators are not very suitable, and

109 749/490

only with a barometric deduction of the heating material satisfactory operation can be achieved. The device consists of two evaporation tanks, the first of which is one with heating steam has operated heating device. According to the invention, the heating devices are in the form of coil heating elements formed and dimensioned heating surface and flow cross-section of this coil heater so that it increase from level to level by a factor between 1.3 and 2.0. Furthermore, there are the evaporation rooms each connected by a line to the coil radiators of the following evaporation stages, in these lines if necessary a separator can be provided, the collecting space of which with the evaporation space of those Stage is connected, from which the vapors are removed.

There is one advantage of the device according to the invention in that the individual evaporation chambers by lines, optionally with a Regulating valve can be provided, are interconnected. These regulating valves can either can be adjusted manually, or they are adjusted automatically by one of the density or those in the following Level contained amount indicating device controlled. To maintain the required The negative pressure in the individual evaporation stages is down at the last evaporation stage arranged extending tube, the length of which is dimensioned so that the weight of the contained in the tube Liquid column ensures the corresponding negative pressure.

The economy of the device according to the invention consists primarily in the saving of heating steam up to about 50% and more, since only the first stage is heated by means of heating steam, while the second stage is heated by the vapors from the previous stage without additional energy expenditure. The saving in coolant (water) is also 50% and more.

For a better understanding of the device according to the invention, the operation of this device described with reference to the embodiment shown in the drawing.

In this drawing, 1 and 2 denote two evaporation vessels, which are through the heating coil systems 3 and 4 are heated. The solution to be evaporated is fed into the container 1 through the line 5, the inflow velocity can optionally be regulated by the valve 6. The arising in the container 1 Vapors are passed through the dome 7 and the line 8 into the separator 9 and from there over the line 10 and the branch lines 11 and 12 are fed to the heating coils 4. The separated in the separator 9 Liquid particles are returned to container 1 through line 13. The administration 14 with the valves 15 and 16 connects the containers 1 and 2 to one another. Stage 2 vapors are passed through the dome 17 and the line 18 in the separator 19, the lower end of which a line 20 is connected to the container 2. From the separator 19, the vapors are via the Cooler 21, which is supplied with coolant through line 22, is fed to separator 23. To the A line is used to draw off the solution, which has thickened to the desired concentration, from the container 2 24, which opens into an overflow vessel 25 and from there via a valve 26 to the barometric Exhaust pipe 27 leads. The line 28 is used to remove the precipitated in the condenser 21 Liquid, and the line 29 discharges the liquid separated in the separator 23. One line 30 branches off from the connecting pipe of the separator 23 to a vacuum pump and leads to the separator 21, into which the condensate of the coil heating element of the second stage opens.

ίο Through the valve 33, the negative pressure in the Second stage coil radiator and thus regulated in the first stage vapor space. A barometric one Discharge pipe 32 carries away the liquid that has collected in the separator 31.

For a better understanding of the mode of operation of the device according to the invention, the mode of operation during evaporation described by means of a few examples.

Example I.

The solution to be evaporated is supplied to the first evaporator (stage 1) and heated by the heater coil disposed therein by means of a saturated vapor of 108 ⁰ C. The pressure in

The boiler of this stage is 310 Torr, see above that the water boils at 78 ° C. The negative pressure in the first boiler remains in the heating coils of the second Received boiler.

The vapors produced in the first stage have a temperature of 78 ^° C. and heat the contents of the second evaporator, which is under a vacuum of 35 to 40 Torr, to such an extent that the water assumed in this example as the filling of the second stage evaporated at 39 ^{0 C.} Of the

Second stage heating steam, d. H. So the vapors of the first stage, when passing through the Snake radiators condensed and excreted barometrically.

With the device described in this example, you can solutions that because of their crust formation can not be concentrated in the circulation evaporators customary up to now, discontinuously or evaporate continuously. In discontinuous operation, the solution to be evaporated is in

fed in all stages and concentrated to the desired concentration and then after switching off the vacuum released.

Example II

This example describes the continuous evaporation of solutions. The line 14 serves as the connection between stage 1 and 2, through which the solution can flow continuously and controllably from stage 1 into stage 2. In stage 1 there is a solution of 16 ° Be, which is heated under a pressure of 310 Torr by a coil heater with heating steam of 109 ⁰ C to boiling. The starting solution of 10Be flows continuously to this solution through line 5

to, the feed being regulated so that the concentration of 16 ° Be is maintained in the boiler will. The vapors are discharged at the top of the boiler and arrive after passing through a separator 9 in the coil heater 4 of the second stage, which they heat to about 39 ° C. In the In the second stage, the solution is in the desired final concentration of 28 ° Be. Through the Connection 14 to the first stage becomes a sequential one

such an amount of the solution of 16 ° Be fed that the amount of solution evaporated in the second stage is constantly replaced. Through the overflow system 24 to 27, the solution concentrated in the second stage is continuously removed barometrically.

Example III

The values given in this example show the advantages of the device according to the invention in see particularly clearly with regard to the saving of heating energy. Level 1 has a heating surface of 17 sqm, level 2 a heating surface of 26 sqm. During operation were over a period of time the amount of solution passed through and the amount of steam used were measured over a period of 250 minutes.

The solution of 10 ° Be fed in was 1,800 l per hour. The one removed in the second stage concentrated solution was 5801 of 28 ° Be. From this the amount of is calculated in both stages evaporated water to 1800 - 580 = 1220 l / h. The steam consumption in the first stage was 750 kg (0.4 atg = 109 ° C). In the first stage, 640 kg of water per hour were evaporated from the condensate downpipe were measured. This results in a steam consumption of 1.17 kg of steam per kilogram Water. The boiling point in the first stage was about 78 ° C. at 310 torr. The concentration in stage 1 and also that of the coating solution in line 14 was about 16 ° Be. The amount of water that must be evaporated in the second stage is calculated as follows: 1220 1 total water less 6401 (condensate stage 2) = 580 l / h, i.e. i.e., for evaporation of 5801 water in stage 2, 640 kg of vapor from the first stage (310 Torr and 78 ° C) are required = 1.103 kg of steam per kg of water. The negative pressure in the second stage was about Torr, the boiling point 39 ° C.

The steam saving is calculated from the difference in steam consumption for evaporation of 1. In the first stage, 1.17 kg of steam are consumed per kilogram of water. For evaporation of 12201, 1427.4 kg of steam would have been required. The actual amount of steam used in the two-stage process is necessary for the first stage alone and is 748.8 kg, while the second stage does not require live steam. The saving is about 47.5%.

Claims (1)

PATENT CLAIM: Device for evaporation of solutions with a tendency to crust formation using coil heaters, characterized in that the device is designed in two stages, the coil heater of the second stage being heated in a known manner with the vapors of the first stage and the heating surface of the coil heater the second stage is 1.3 to 2.0 times the heating surface of the coil heater of the first stage and the treated solution and the heating medium of the second stage are withdrawn by means of a known barometric exhaust device. Considered publications:
German patent specifications No. 586 163, 747 576,
293, 861540;
British Patent No. 252505;
U.S. Patent No. 1390,677. 1 sheet of drawings © 109 749/490 12.61