DE1519610A1 - Thermal rectification column - Google Patents

Description

Thermisclie rectifying column has long been used in technology Decomposition of liquid mixtures made use of the principle of rectification, which consists in the fact that vapor and liquid are led in countercurrent to one another without external heating or cooling, an adiabatic mass transfer between Steam and liquid the enrichment of the lower-boiling component in the steam causes. Columns are used to carry out this adiabatic rectification process used with various internals and fillings, which on the one hand have a good contact between vapor and liquid and on the other hand intense flow and mixing caused by vapor and liquid. All of these columns have the disadvantage that for a good mass transfer there is a noticeable pressure drop in the steam in the direction of flow occurs, which is very disadvantageous, especially with temperature-sensitive substances affects. Because this Substances must be rectified at low temperatures be, whereby small pressures are required, but rruckverlusten at noticeable often cannot be kept deep enough.

To counter this disadvantage, there are columns with a small pressure drop has been developed, but characterized by relatively very high production costs, are.

Therefore, it is advantageous for liquid separation at high vacuum made use of the principle of so-called thermal rectification. Ilierbei the lower boiling point is enriched in the steam, not by the above described adiabatic exchange of substances, but by repeated condensation and evaporation with heat dissipation and supply to and from the outside. here can the Pressure drop in the steam can be kept low because the steam speed and the Steam flow are no longer of great influence on the enrichment.

To carry out this process of thermal rectification is so far in technology use exclusively of so-called thin-film evaporators made, which are equipped with a cooled rotor. The one for the implementation of Process required condensation takes place on this rotor, evaporation on pipe with an outer heating jacket instead. this thin film rectifier has has some serious disadvantages due to its type of construction.

The main disadvantage resides in the difficulty caused by the externally driven rotor arise. In the case of a high vacuum, this rotor causes sliding Seals that limit the vacuum that can be achieved. The drive and the seal brings with it an operational malfunction as well as wear and tear and special maintenance themselves. Furthermore, the throughput is limited in this thin-film rectifier because Because of the externally driven rotor, only one tube is arranged in each apparatus can be. An enlargement of this pipe as well as the heating and especially the cooling surface on the rotor is only possible to a very limited extent. Furthermore, with a given flow cross-section of the pipe, d. H. with a given diameter, the heating and cooling surface only through Lengthening the apparatus can be enlarged, which is only possible to a very limited extent.

All of these disadvantages become apparent in the device according to the invention avoided in which those responsible for the condensation and Evaporation required Heat transfer surfaces formed by multiple helical pipe coils will.

These pipe coils are arranged in such a way that @ and heated pipes lie one on top of the other and one on top of the other. The one between the pipes Steam flowing upwards is repeatedly partially condensed on the cooled tubes. The con (lensat dripping from the cooling tubes onto the heating tubes, as well as the one at the top Return flow supplied to the end of the column is repeated in part on the heated tubes evaporates. Through this repeated condensation and evaporation, the enrichment becomes or separation of the components of the mixture causes.

The device according to the invention avoids all the disadvantages of the previous one known thermal rectifiers. According to the invention none are mechanical moving rotors with the resulting drive, sealing and wear problems needed. The rigid seals of the device according to the invention that achievable vacuum is practically not limited downwards. Furthermore, the thermal Rectifier according to the invention can be built for any throughput, by increasing the number of coils. The relationship between Heat transfer surface and cross-sectional area through which the steam flows through suitable Any choice of snake spacing be chosen without the amount to change the column.

As a result, the pressure drop occurring in the steam can also be arbitrary be kept low.

Since the heat transfer surface formed by the pipe coils with is associated with relatively low costs, it can also be chosen as large that there is a small heating surface load in spite of the high throughput results. This has a beneficial effect on the pressure loss and the separation efficiency, as well on the heat consumption.

The distribution of the reflux liquid at the top of the column can be done, for example, through one or more perforated manifolds. These However, distribution does not have a great influence on the action of the column according to the invention, since the wetting of the column tubes is predominantly caused by that on the cooling tubes inevitably formed condensate happens. This condensate runs on the weak inclined pipe coils and drips onto the heated pipes below. As a result, all pipes are wetted evenly. The slope of the snakes can adapted to the properties of the liquid.

To allow the condensate to drip off at a suitable point force, In a preferred embodiment, the cooling tubes are provided with drip rings. This can result in mixing, which is fundamentally harmful in all separation processes be sprayed by liquids of various compositions.

Qm with a small liquid load on the pipe coil then one more to achieve complete wetting, especially of the heated coil the iieizrotlre in a preferred other embodiment such under the cooling tubes arranged that each cooling and heating tube along a cladding line be @ hrung. As a result, the condensate formed on the cooling tubes will drain over the entire pipe length and the associated complete wetting of the entire heating pipe surface achieved. The drainage of the condensate at a suitable point without mixing liquids different concentration can thereby be achieved by suitable incline of the snakes In order to increase the pitch of the pipe coils with larger coil diameters and constant To be able to keep the vertical distance the same, in a preferred embodiment the pipe coils are multi-threaded with a larger coil diameter.

@m to require mixing in the horizontal direction in a further preferred embodiment the snakes alternate from the inside to the outside clockwise and anticlockwise.

The invention is shown by means of the drawing, which is an example Embodiment is illustrated, explained in more detail: Shown are: FIG. 1 a column according to the invention in longitudinal section; FIG. 2 shows a section in the plane AB according to FIG. 1 t:. 3 shows a partial longitudinal section through the pipe systems for heating and cooling. The cooling pipes are shown in a closed line and the heating pipes are shown in dashed lines.

Inside the separating column 1 is the cooling system 2 and the heating system 3 arranged. Heating and cooling pipes are expediently arranged caxially. That Heating medium exits at 4 and 5, the coolant is added at 6 and discharged at 7. The lower boiling point withdrawn in vapor form at the top of the column at 8 becomes a usual capacitor directed; at 9 is the bladder with the vaporizer connected; at 1o the return fluid becomes a dispensing device 11 headed.

The number of coils depends on the size of the columns. Essential is just that there is at least one cooling and one heating system within the column is available.

The thermal rectifying column according to the invention becomes particular advantageous for cleaning and separating high-boiling, temperature-sensitive Liquids are used, with one opposite the known columns for thermal Rectification represents a significantly more economical device, whichever can be adapted to the required performance and the previously controlled pressure range allowed to fall significantly below.

Claims (5)

P a t e n t a n s p r ü c h e 1.) Thermal rectification column, thereby characterized in that the cooling and heating systems are made by helical coils (2 or 3) are formed. 2.) Device according to claim 1, characterized in that the cooling tubes are provided with drip rings (12) at certain intervals. 3.) Device according to claims 1 and 2, characterized in that that the heated pipe coil is arranged directly under the cooled coil in such a way is that these snakes touch along a surface line. 4.) Device according to claims 1 and 2, characterized in that that the pipe coils are designed with multiple turns depending on the winding diameter, whereby the same inclination of the pipes is achieved with the same vertical distance. 5.) Device according to claims 1 to 4, characterized in that that the pipe coils alternate from the inside to the outside with opposite directions of rotation are executed.