DE3131785A1 - OPEN CAPACITOR - Google Patents

Description

BAYER AKTIENGESELLSCHAFT 5090 Leverkusen, Bayerwerk

Central area Hö / bc / cjj _{Aug <}

Patents, trademarks and licenses

Open capacitor

The invention is directed to a method and apparatus for low-noise introduction of large quantities of steam into a flowing liquid ^1.

According to DE-OS 2 439 562, the heating of water is known with water vapor, the water vapor in a open tube or tube bundle is passed, is expanded and condensed in this, and the condensate in the water to be heated, surrounding the tube or tube bundle, emerges, whereby the tube length and the tube diameter are dimensioned so that the entire water vapor at the latest at the end of the tube or tube bundle is completely relaxed and condensed.

It is also known to reduce noise through
Avoiding large steam bubbles, injecting steam through many small holes, setting the liquid speed high (up to 20 m / sec), generating turbulence that promotes high dispersion, setting the steam speed high (close to the speed of sound) and bringing the steam as deeply as possible into the

Pour liquid into it.

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At least during the heating-up processes, where the liquid temperatures are still low, and because of the high flow speed, such steam heaters still cause a lot of noise. So (water outlet temperature 60 ⁰ C NW 65, water circulation 25 m / h, vapor feed 400 kg / h) is in such a Dampfanwärmer the noise level 98 dB (A).

Another disadvantage of known steam heaters is their poor controllability. The admissible ratio of The maximum to the minimum steam injection is a maximum of 7: 1. With smaller amounts of steam, liquid penetrate into the steam space in an uncontrolled manner and lead to condensation hammering.

For special steam heaters with a larger control range Do the feed-in points have to be closed gradually as the steam load decreases? known are electrically and pneumatically operated sliding sleeves. Such devices are very prone to failure.

The object of the invention is to provide methods and devices for the low-noise introduction of large amounts of steam in liquids, which are characterized by the fact that a safe and stable work is achieved.

In terms of the method, the object is achieved in that the steam is first fed to a heat exchanger at the end of which it still enters the liquid in vapor form, with such flow conditions that the in the form of a

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Steam column connected to the heat exchange element, extends axially parallel to the flowing liquid into the flowing liquid.

The device is characterized in that the Under the operating conditions, the heat exchange surface is not sufficient to completely condense the steam, and the openings of the heat exchange element or elements are designed with regard to the flow so that the escaping steam in the form of coherent columns propagating from the heat exchange elements reaches into the liquid parallel to the flow.

Further advantageous designs are described in the subclaims.

The decisive advantage of the invention is that it is within a wide control range results in a stable and quiet driving style. When starting where there is a high temperature difference between the vapor and the liquid prevails, it can happen that already within the heat exchanger the Steam so much heat is extracted that it condenses there and condensate from the heat exchange elements escapes, which then mixes noiselessly with the amount of liquid to be heated. The lower the Temperature difference between vapor and liquid will, the further the front will become where the vapor condensed in the heat exchange element, move to the outlet side of the heat exchange element until finally Vapor enters the liquid. The method aims at the operating states, one

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"Steam column" coming out of a heat exchange element, extends into the liquid as a stable structure. If the operating conditions change, the Length of the steam column and thus the direct condensation surface in a simple way these changes. The openings at the end of the heat exchange elements must be like this be designed and arranged that the vapor column emerging from the heat exchange elements in the liquid protrudes, is not sheared and divided by the flowing liquid, but that it is practical is an elongated heat exchange element without a partition. The system is stable across the board. Such a Operation is new and very advantageous. In the literature it is always advised to use "open heat exchangers" in such a way that that the heat transfer medium condenses completely within the tubes. The device according to the invention is characterized by a smaller "apparatus" heat exchange surface.

In the case of the open capacitor according to the invention, both Direct current operation as well as counter current operation possible. Compared to the disadvantage of countercurrent operation the direct current operation, that because of the added condensate with relatively warmer liquid must be cooled, the advantage of countercurrent flow is the larger mean temperature differencesζ opposite to. You can calculate whether the advantages or disadvantages outweigh the disadvantages.

The device of the present invention has excellent Control characteristic. The heater adapts itself automatically to the respective amount of steam,

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from 0 to the design maximum. The control ratio is theoretically infinite. Control is purely hydraulic and has no moving parts. To there is practically no limit at the top, since the number of heat exchange elements can be increased at will leaves. So the steam speed does not need to be over to be increased to an optimum.

In the case of straight pipes, a particularly high packing density can be achieved, which is a large ratio from steam exit areas to the cross-sectional area of the flowing liquid results. In relation to the apparatus cross-section, high values for the direct condensation surface between vapor and liquid and thus for the condensation performance a.

In the design of the open capacitor, depending on requirements in terms of material and geometry the most diverse requirements are met. The heat exchange elements can be cylindrical or box-shaped be. A forced deflection of the liquid flow can be carried out within the bundle. In principle, it is also possible to send the liquid through the heat exchange elements and directing the steam around the elements; through the exchange elements charged with liquid in this way a guidance of the steam can also be achieved; in this case the columns of steam emerge from the "jacket area" and are surrounded by corresponding "columns of liquid" from the heat exchange elements.

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in order to achieve high performance, the steam must be in a flowing liquid can be introduced. Usually this is a pump and appropriate Guide elements around the heat exchange elements (often identical to the housing) are required. It can but also a convection flow will be sufficient. Because the state where the column of steam goes straight up or exits downwards, is most stable, a vertical arrangement of the heat exchange elements is required preferred. In the case of very long heat exchange elements, it may be necessary to support each other in order to a beating or sagging of each Avoid items. A sieve thread can also take on this task.

Around a low-eddy flow at the ends of the heat exchange elements To achieve this, it is advisable to bevel the ends. Especially with thick-walled pipes an inner or outer bevel is appropriate.

The largest control range and the largest steam output can be achieved with vertical installation and steam guidance from top to bottom.

The device can be inexpensively made from standard pipeline parts produce; they are also available in stainless steel quality. The tube sheets can be made from Standard flanges can be produced on NC machines. The apparatus can also be used without its own Housing can be pushed into a corresponding pipeline system.

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The invention is illustrated in the drawing and further described below. Show it:

Fig. 1 tube bundle condenser open on one side; 2 flat channel capacitor open on one side; 3 steam heater in countercurrent operation; 4 steam heater in direct current operation; 5 an angular flat-chamber capacitor; Fig. 6 section through the upper part of the insert

a capacitor according to FIG. 5; 7 open tube bundle condenser in a container.

The open tube bundle condenser, as it is shown schematically in Fig. 1, consists essentially from a plug-in tube bundle 1 which protrudes into a housing. The upper part of the apparatus is very similar with a "classic" heat exchanger. The space around the tubes 3 enters through the side of the housing attached nozzle 4 the liquid in or out. The main difference occurs at the bottom Area of the apparatus. The tubes 3 do not end in a tube sheet 5, as above, but open free. Steam is fed in via the nozzle 7. The liquid enters at 4 and at the nozzle 6 off, if DC operation prevails, it enters at 6 and exits at 4, countercurrent operation. Independent whether it is operated in cocurrent or countercurrent operation, with small temperature differences between Liquid and vapor protrude from the tubes 3, quite stable vapor columns 8 into the liquid.

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Vertical tube bundles 1 are preferred. A particularly compact "steam column" is obtained from one Steam entry from top to bottom; in the opposite case, the steam column is drawn longer.

The tubes 3 can run out bluntly; in order to generate as little vortex as possible, it can be advantageous Chamfer pipes inside or outside.

FIG. 2 shows a differently designed tube bundle 1. Instead of straight cylindrical tubes as in FIG. 1 there are flat chambers here. In the case of a longer inner tube bundle, it can be useful to use supporting fabric to use to improve the mechanical stability or baffles to divert the flow around the pipes; they are not drawn here. Towards the end of the tube bundle, however, the flow should around the pipes are largely parallel to the pipes with little eddies. Since the pressure differences within and are very small outside the flat chamber,

the wall thickness can be very low.

Typical applications are shown in FIGS. Both figures have the same characteristics same reference numerals. In Fig. 3, the steam heater 20 operated in countercurrent, in FIG. 4 in cocurrent for heating an agitator container 21. The water 22 in the heating jacket 23 of the agitator tank 21 is circulated via pipes 24 by the centrifugal pump 25 and thereby by the heater 20 promoted. To increase the temperature, the cas-

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Cadence temperature control 26 the valve 27, and steam flows into the heater 20. A pressure maintenance control 29 keeps the pressure in the system constant by removing excess condensate (possibly also cooling water) via the Valve 30 discharged. If the product temperature in the agitator container 21 is to be lowered, the closes Temperature control 26 the steam valve 27 and opens the cooling water valve 31.

With the described warming up, a noise is generated practically avoided when introducing steam into liquid, as it is possible with these apparatuses to suppress the usual blistering with unavoidable cavitation. By cooling down the Steam in the heat exchange elements becomes the steam speed considerably reduced, or at the beginning of a heating process only condensate occurs anyway from the pipe ends. But even if the steam has not yet condensed inside the tube and Vapor columns 8 reach into the liquid, forms a stable steady state without cavitation impacts is achieved. For these reasons, the Tubes 3 of the tube bundle 2 have a high thermal conductivity; Plastic pipes that are occasionally used for Noise abatements have been proposed, would be weaker suitable. Straight pipes of the same length have proven to be the best. A heater like in Fig. 1 shown, for example, was equipped with 132 small tubes made of stainless steel; the wall thickness of a tube was 1 mm, the diameter 6 mm and the length 800 mm. The case, also made of stainless steel,

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had a nominal width of 100. With such a heater, a 10 m agitator vessel was heated up via pressurized water heating circuits by introducing 400 kg of water vapor / h. The water flow rate was about 25 m / h, the water temperature before the introduction of steam 25 ⁰ C, the maximum allowable water circulation temperature was 130 ⁰ C, the water pressure at the entrance to heaters 4.2 bar, of steam pressure 5 bar. The noise level during operation was 70 dB (A). It was not measurably increased by the introduction of steam. On the other hand, with a steam jet of conventional design and roughly comparable power, a noise level of 98 dB (A) is measured at the beginning of the heating process and a noise level of 80 dB (A) at the end of the heating process. Another advantage of the heater according to the invention is the relatively low pressure loss on the liquid side and the very large steam control ratio. In the case of the heater described above, the pressure loss without the introduction of steam was less than 0.1 bar; with conventional heaters it is 0.6 bar. According to the manufacturer, the permissible steam control ratio is 1: 7; in special designs up to 1:60. In the case described above, the steam input varied between 0 and 400 kg / h; the steam control ratio is practically infinite; an enlarged valve also allowed steam entry of 1200 kg / h to be achieved without the noise increasing. The upper limit of performance has not yet been reached.

In Figures 5 and 6 there is another form of the invention Device shown. It deals

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around a flat chamber bundle 40 similar to that in FIG. 2 in a rectangular housing .41. The steam enters laterally through the flange 42 and the liquid flows through the housing 41 in the direct current of top 43 to bottom 44, or in countercurrent from 44 to 43.

Details of the heat exchange elements are shown in section in FIG. The steam enters the flange 42 in the cage 45; this has the function of supporting the flat-chamber heat exchanger elements 46 and to take care of the steam distribution. Rings 44 are installed within the flat chambers 46, which have a To prevent compression of the flat chambers, but allow the passage of steam. Between The flat chambers 46 are in turn rings 48 to ensure a minimum distance between the flat chambers 46. The same function also has knobs on the outside of the flat chambers. In addition, serve these knobs 49 still improve the heat transfer. With the yoke 50, the flat chambers and the rings pressed together.

According to FIG. 7, a tube bundle condenser can also be operated for heating without forced circulation. By feeding in steam via the flange 60, cooler liquid is drawn through the openings 61 at the bottom sucked on the housing 62, into which the open-top heat exchange elements 63 extend. It comes to a convection flow. Here, too, stable columns of steam can form, which are

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elements 63 starting upwards into the liquid. To avoid vortex formation, which Bubbles torn from the columns of steam should be near the ends of the heat exchange elements Vapor and liquid flows are basically guided in parallel. The steam should be as possible Flow vertically into the liquid. In the case of a horizontal column of steam, the end of the column is due to bent upwards due to the lower vapor density, whereby at least with large steam outputs and thus Long columns of steam, steam bubbles can be torn out of the columns and cavitate.

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Claims (5)

Patent to sayings Method for the low-noise introduction of large amounts of steam into a flowing liquid, thereby characterized in that the steam is first passed through a heat exchanger to which At the end it still enters the liquid in vapor form, such flow conditions being observed be that it is axially parallel in the form of a steam column which connects to the heat exchange element to the flowing liquid extends into the flowing liquid. 2) Device for the low-noise introduction of large amounts of steam into a flowing liquid, whereby the steam is fed into a tube bundle open on one side as a heat exchanger, characterized in that that the heat exchange surface is not sufficient under the operating conditions to the To condense steam completely, and the openings of the heat exchanger (s) (3,10, 46,63) are designed with regard to the flow in such a way that the escaping steam is in the form of itself from the heat exchange elements propagating contiguous Columns (8) extends into the liquid parallel to the flow. 3) Device according to claim 2, characterized in that the flow is perpendicular. Le A 21 173 4) Device according to claims 2 and 3, characterized in that that the heat exchange elements are straight tubes (3.63). 5) Device according to claims 2 and 3, characterized in that the heat exchange elements (10,46) are prismatic. Le A 21 173