DE2840066B2 - Device for obtaining pure water from sea water - Google Patents

Description

a) two film evaporators (-) in the form of vertical tube bundles - designed in cross section as a segment of a circle without a jacket -;

b) two containers (4) at the bottom with the upper tube plate of one of the film evaporator of the same section - in the last section without film evaporator, however, connected to the discharge pipe for salt solution - and above the animal the lower tube plate of the Filmverdamp- ^w fers ti "overlying Section - connected in the first section to the feed line for sea water - are connected;

c) a bottle neck-like upper course (6) at the bottom of each container for the passage of the Saline solution from the container (4) to the underlying tube plates and to compensate for the positive pressure difference;

d) openings (7) on the upper side of each container with the exception of the container in the first section;

e) one or more siphon pipe (s) to extract the gathering at the bottom of each section Condensate and for re-introduction at a middle point of the next: section;

f) horizontally arranged tube bundle exchanger (3) for preheating the sea water with Steam;

g) Inert gas lines from section to section to the vacuum system;

according to DE-PS 2334481, characterized in that the tube bundle exchanger (3) - except in the last section - vertically are arranged and that the last section has a horizontal tube bundle exchanger acting as an end condenser, the tube plates of which are fixed diametrically on opposite parts of the column under the last section.

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The main patent - DE-PS 23 34 481 - concerns one Device for the extraction of pure water from sea water according to the multi-effect process with heat exchanger, separation containers, feeds for sea water and primary steam, discharges for salt solution and Pure water and connection to a vacuum system in the form of a vertical column, divided into several cylindrical sections each containing: eo

a) two film evaporators in the form of vertical tube bundles - in cross section as a segment of a circle trained and without a coat -;

b) two containers that are on the bottom with the upper μ Tube plate of one of the film evaporators of the same section - in the last section without film evaporator, but connected to the discharge line for saline solution - and at the top with the lower tube plate of the film evaporator of the section above - in the first section connected to the feed line for seawater - are connected;

c) a bottle neck-like overflow at the bottom of each container for the passage of the saline solution the container to the underlying tube plates and to compensate for the positive pressure difference;

d) openings on the top of each container with Exception of the container in the first section;

e) one or more siphon pipe (s) for the removal of the collecting at the bottom of each section Condensate and re-introduction at a middle point of the next section;

f) horizontally arranged tube bundle exchangers for preheating the sea water with steam and

g) Inert gas lines from section to section to the vacuum system.

The additional application DE-OS 26 25 358 brings a further development of this device by the Tube bundle exchanger for preheating the seawater housed in a continuous tube which is located in the container containing the saline solution and divides it into two tubs

The present invention brings a modification of the device according to the main patent to the effect that that the tube bundle exchanger - except in the last section - are arranged vertically and that the last section has a horizontal tube bundle exchanger acting as an end condenser, whose tube plates are fixed diametrically on opposite parts of the column under the last section are.

The modification of the main patent according to the invention offers for systems with high throughput, especially with regard to capital expenditure and energy consumption, considerable advantages.

The invention is further explained with reference to the figures:

The F i g. 1 shows a longitudinal section and FIG. 2 shows a cross section according to A-A of FIG. 1 of a section of a Column 1 for the desalination of sea water from the following parts:

a) Vertical tube bundle film evaporator 8 without a jacket;

b) Container 4 for collecting the seawater, connected at the bottom to the upper tube plate SA of the film evaporator, these containers - in the last section without film evaporator - being connected to the discharge pipe above the lower tube plate of the section above. The first section of the tank is connected to the feed line for the seawater.

c) Then at the bottom of each container 4 there is a system 6 which allows the flow of water into the second container 4 '; its bottom plate is the upper tube plate 8A of the film evaporator below. In this way a positive pressure difference between the container and the film evaporator is eliminated.

d) Finally, in the upper part of the side wall of each container 4 - with the exception of the Container of the first section - openings 7 for the extraction of steam and

e) one or more siphon pipe (s) for draining the

condensate collecting at the bottom of each section and discharging to a central point of the next section.

Q The (tube bundle) heat exchanger 3 is used for Preheating of the fed-in water with steam, which is obtained in each section.

g) Finally, there are power systems for inert gases between the individual sections may be present in the vacuum system.

According to the invention, the tube bundle film evaporator 3 in each section have a cross section in The shape of a segment of a circle 8 'and the heat exchanger 3 for preheating the water fed in has a circular cross-section and is arranged vertically. Its lower tube plate rests on the Parting plane 16 to the next section and the upper tube plate is with the parting plane 16 of the one above Section connected via a heat-expandable connection 15, which expansion differences the column and the tube plates are able to compensate for by different materials and has a single passage for upward flow in the section. The heat exchanger 3 is located in the segment of a circle of the column 1, which is still free from the Rlmverdampfern 8 will.

The last condenser below the last section is a horizontal tube bundle condenser with fixed tube plates on diametrically opposite parts of the column and is used for Condensation of all the steam present in the last section.

From Fig. 2 shows the position of the heat exchanger 3 and the film evaporator 8.

The invention is further illustrated by the following examples: Example 1

Initial values:

Seewarer salinity 35,000 ppm

pH at 20 ° C 8.1

Temperature 26 ° C

Primary steam 3atül35 ° C

Fresh water output 1 500 mVh

Fresh water temperature 46 ° C
The salinity of the fresh water is 15 ppm

Horizontal

Vertical

number

of sections

number

of columns

0 1st column

0 2nd column

Height of 1st column

Height of 2nd column

Power requirement

15th
2

8m
8 m

37.2 m
40.8 ni
2.35kWh / m '

15th
2

6.5 m

6.5 m

41.4 m

45 m

1.86 kWh / m '

The embodiment with a horizontally arranged tube bundle exchanger for preheating the seawater requires tube plates with a diameter of 2.45 m, associated with great problems in the Construction and support of the tube bundle inside each section due to their own weight and the considerable sealing problems on the flanges due to possible air ingress from outside and finally - what is probably most important - that practical handling of the tube bundle of this kind Size is not possible if it is taken out of the column for repair or maintenance or in it should be used.

The fact that in the device according to the invention the total length of the two columns by 8.4 m larger than in the known embodiment with horizontally arranged heat exchangers for preheating, should not lead to the deceptive view lead to a substantial reduction in diameter by eliminating the outer Distributors for the exchanger, which inevitably have to be made of a high-quality material (Copper / Nickel 90/10), the reinforcement must be made of an expensive material, so that considerable initial costs can be saved, as can be seen in the following example

Desalination with a vertically arranged heat exchanger for preheating is special interesting for large systems, as can be seen from the following table, in which the main characteristics of two Systems are combined, i.e. with a horizontal and vertical arrangement of the heat exchanger for preheating.

Example 2 Output data: 35,000 ppm Salinity of the lake water 8.1 pH at 20 ° C 26 ° C Sea water temperature 3 atü and Primary steam 135 ° C 535 mVh Fresh water performance 46 ° C Fresh water temperature 15 ppm Salinity of fresh water

With the lower throughput of 535 mVh, which can be described as medium to higher, the advantages achieved according to the invention not so clearly as in Example 1, however, a considerable saving in material is found nonetheless

Horizontal

Vertical

number

of sections

number

of columns
0 1st column
0 2nd column
Height of 1st column
Height of 2nd column
Electricity demand

15th
2

4.7 m
4.7 m
37.2 m
40.8 m

15th 2

4.35 m
4.35 m
39.8 m
44 m

2.35 kWh / m ³ 1.86 kWh / m ³

This comparison is closer and dusty evaluate the actual economic benefits more precisely.

The total weight of the two columns is about 33 t less. The very expensive one accounts for 5.5 t of this Copper / nickel alloy 90/10 and the rest on carbon steel, generally with tenprpm

Material or plated in an expensive manner.

In the case of a unit with a laterally extendable, horizontally arranged tube bundle exchanger for the To preheat the sea water, a scaffold with working platforms for everyone must be outside the columns -, Section and hoists for extending and retracting the heat exchanger may be provided.

According to the invention, both the evaporator tube bundle and the preheating tube bundle are extended vertically from the top of the columns. Man in therefore only requires a hoist of the appropriate power above the head of the columns, which is both Can serve columns and which rests on a platform on the column heads. You need So for the work outside the column no r> scaffolding, which is estimated to have a weight of about 140 t and can save the work involved in erecting such a scaffold.

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the Krstelliingszeit, a cactor that is present at the present Market position should not be overlooked.

In addition to the weight reduction and thus a reduction in investment costs are also Savings in operating costs achieved through lower power consumption.

For an annual output spread over 330 Working days and with electricity costs of 30 Lire / kWh, the following savings result:

(2.35 - 1.86) χ I 500 χ 24 χ 330 χ 30

= 174 636 000 lire annually.

calculated for example 1 and for example 2
(2.35 - 1.86) χ 535 χ 24 χ 330 χ 30

= 62 286 840 lire.

The device according to the invention is therefore suitable not only for large-scale systems, but also for systems with medium power in the order of magnitude

becomes cheaper if the hydraulic one has the same performance Pressure to be overcome from 180 up 120 m can be lowered. All of this has more of an influence on the importance of systems with capacities from 800 to 1000 mVh and above, which are becoming increasingly widespread.

For this purpose I sheet drawings

Claims (1)

Claim: Modification of the device for the extraction of pure water from sea water according to the multi-effect process with heat exchangers, separation tanks, Inlets for sea water and primary steam, discharges for salt solution and pure water as well Connection to a vacuum system, in the form of a vertical column (1), divided into several cylindrical sections each containing: