DE7345767U - COMBINED HEAT EXCHANGER AND MIXER - Google Patents

Description

AG FA-G EVAERT A3

PATENTABTElLUNQ

LEVERKUSEN

February 22, 1977

Ki / Kr / eb

Combined heat exchanger and mixer

The innovation concerns a combined heat exchanger and mixer, consisting of an outer tube and an axial inner tube, are arranged on the mixing segments and through which a heating medium flows.

In the manufacture of photographic materials, the silver halide emulsion is mixed with photochemical Additions such as color couplers, sensitizers, stabilizers, provided and then in a liquid state on a running track applied. When applied, the emulsion usually has a temperature between 35 and 40 °. To this For this purpose, temperature control devices must be installed. It has now been found that when tempering photographic In contrast to conventional heat exchangers, emulsions are subject to particularly critical requirements. Photographic emulsions are particularly sensitive to overheating. The temperature control must therefore be as possible small temperature differences between the emulsion and the heating medium. Another danger of overheating is that the emulsion flowing along the boundary layer of the heat exchanger gels, so that the heat transfer is considerable is reduced. It has now proven to be beneficial if the mixing and temperature control are not carried out separately, as was previously the case Steps takes place, but is carried out simultaneously. The well-known static mixers were used for this purpose (see DT-OS 1 557 118) modified and with a heat exchanger combined.

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The innovation is characterized. That in the combined Heat exchanger and mixer, the ratio of the outer diameter C of the inner tube 3 to the clearance A of the Outer tube is in the range from 1: 1.9 to 1: 2.3.

Normally, when dimensioning, one starts from the consideration that with increasing inner pipe diameter, the Heat exchange increases, but the mixing effect decreases. It has now surprisingly been found that the The ratio of the inner pipe diameter C (outer dimension) to the inside diameter A of the outer pipe varies from 1: 19.9 to 1: 2.3 without significantly changing the optimal working conditions.

One should initially expect that the heat exchange in a static mixer modified in this way is unfavorable because of the relatively small surface area of the inner tube and because of the radial temperature gradient along a mixing segment. In those cases in which the mixing section had to be heated, the static mixer was therefore previously provided with an external heating jacket. Comparative tests of the new mixer design (inner tube heating) have shown that the heat exchange compared to a static mixer with outer jacket heating (with the same primary output) can be increased by 200%. A physical explanation for this unexpectedly large increase is still pending. Presumably, particularly high heat transfer coefficients are achieved at the mixed segments as a result of the constant shifts and the associated boundary layer disturbances. Of course, the mixer can also be equipped with a conventional outer heating jacket in addition to the inner pipe heating.

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Another advantage of the mixer is the great mechanical stability of the inner mixing insert. The stability is important when using the mixer in making photographic emulsions. The mixer often has to be in darkened rooms can be opened and cleaned. The improved stability prevents the mixing segments from bending and thus jamming of the mixing insert when reassembling after cleaning. Because damage to the mixing insert is no longer to be feared, the diameter of the mixing segments can practically match the inner diameter of the Match the outer tube. In this case the mixing conditions are optimal.

The use of the combined heat exchanger and mixer is because of the same residence time of all product particles and the extensive homogeneity through mixing with intensive heat exchange with the heat carrier for sensitive photoemulsions Can be used successfully up to a viscosity of 200 cp.

The heat exchanger mixer system described can be used for all temperature control problems in which it is as gentle as possible thermal treatment of the product arrives, can be used with success. In the case of substances that are sensitive to overheating often the requirement for a residence time spectrum that is as uniform as possible. This requirement is combined by the Heat exchanger mixer met in an excellent way. Apart from these product-specific requirements, you can with the new system, the energy losses in larger systems can be reduced considerably.

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According to a particular embodiment, the ratio of mixing segment diameter A to mixing segment length B is 1: 1 to 1: 1.5.

For mixing with good heat transfer at the same time the ratio of mixing segment diameter (A) to mixing segment length (B) between 1: 1 to 1: 1.5 has proven to be special proved beneficial.

In the following, an embodiment of the invention is described in more detail with reference to a drawing. Show it:

Figure 1: A top view of the modified static

Mixer and
Figure 2: A top view of the modified static

Mixer with additional outer jacket heating.

The combined heat exchanger and static mixer according to FIG. 1 consists of the outer tube 1 and the mixing insert 2. The mixing insert 2 is formed by the inner tube 3 to which the mixing segments 4 are welded or soldered. The emulsion enters the mixer through the nozzle 5 and leaves it at the other end 6. The heating medium, in this case water at a temperature of 35 to 40 °, flows through the inner tube 3 as shown to mixed segment length B is 1: 1 to 1: 1.5. The ratio of inner tube diameter C (outer dimension) to outer tube diameter A (inner dimension) is in the range from 1: 1.9 to 1: 2.3. The length of the mixer is not critical. It depends on the required mixing properties and the maximum permissible pressure loss.

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The combined mixer and heat exchanger according to FIG. 2 is provided with an additional outer jacket heater. she consists from the coils 7 and the outer jacket 8. The bracket 9 on the head of the mixer is designed so that the Connection piece 10 for the heating medium in the mixer can be inserted into the inner tube 3. The temperature control water enters at 10, and leaves the mixer at 11. The emulsion is fed to the mixer through port 5 and enters after completion Mixing and temperature control through the central nozzle 6 are canceled again, i.e. the emulsion is countercurrent to the temperature control water guided. The two connections 12 and 13 provide the temperature control water supply or discharge of the outer jacket heating.

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Claims (2)

gohutz claims; 1. Combined heat exchanger and mixer, consisting of an outer tube and an axial inner tube, on the mixing segments are arranged and through which a heating medium flows, characterized in that the ratio of the outer diameter C of the inner tube (3) to the inside diameter A of the outer tube is in the range from 1: 1.9 to 1: 2.3. 2. Apparatus according to claim 1, characterized in that dadtirch the ratio of mixing segment diameter A to mixing segment length B is 1: 1 to 1: 1.5. A-G 1213 - 6 - 7345767 06/23/77