ROTARY EVAPORATOR AND CONTROL MODULE THEREFOR

Abstract

The invention relates to a rotary evaporator (1) which is designed for the automatic execution of decompression steps during an overall process, in particular during distillation. With the decompression steps (III) to (VI), a complete removal of residual portions of condensed distillate at the inlet connection (71) of the intermediate valve (7) and in the condenser (5) of the rotary evaporator (1) can be accomplished. The rotary evaporator (1) has an electronic control module (9) which is designed and programmed to automatically carry out the decompression steps and other process steps with the rotary evaporator (1).

Claims

1. Rotary evaporator (1), having a system pressure generator (6), an intermediate valve (7) connected directly or indirectly between a condenser (5) and each receiving flask (81, 82, 83), a control module (9) designed for electronically controlling the system pressure generator (6) and the intermediate valve (7) and, optionally, a temperature control bath (4), characterized in that in that the control module (9) is designed and programmed for the automatic execution of subsequent decompression steps (III) to (VII) in the specified sequence within a step i or as a separate step i of in each case n consecutive steps of an overall process: (III) the intermediate valve (7) open, reduction of a first system pressure p.sub.S1i to a first limit pressure p.sub.Gai within an upstream decompression time interval ?t.sub.3i, (IV) with the intermediate valve (7) open, increasing the limit pressure p.sub.Gai to a holding pressure p.sub.Hi in a subsequent decompression time interval ?t.sub.4i, (V) with the intermediate valve (7) open, maintaining the holding pressure p.sub.Hi for a next decompression time interval ?t.sub.5i, (VI) with the intermediate valve (7) open, reducing the holding pressure p.sub.Hi to a second limit pressure p.sub.Gbi in a further decompression time interval ?t.sub.6i and closing the intermediate valve (7) when the second limit pressure p.sub.Gbi is reached, (VII) with the intermediate valve (7) closed, regulating the second limit pressure p.sub.Gbi to a second system pressure p.sub.S2i within a final decompression time interval ?t.sub.7i, where i is a natural number from 1 to n and n also corresponds to a natural number from 1 to the number of steps i which can be carried out with the rotary evaporator with respect to identical, partially identical or different operations within an overall process, the control module (9) being used to control the first system pressure p.sub.S1i, the second system pressure p.sub.S2i, the first limit pressure p.sub.Gai, the holding pressure p.sub.Hi, the second limit pressure p.sub.Gbi, and the time interval ?t.sub.5i can be set or the first limit pressure p.sub.Gai, the holding pressure p.sub.Hi and the second limit pressure p.sub.Gbi can be set automatically in relation to the first system pressure p.sub.S1i, the time intervals ?t.sub.3i, ?t.sub.4i, and ?t.sub.6 are each defined as switching times on the control module (9), the Zeitabschnitt ?t.sub.7i can be set with the control module (9) or can be defined as a switching time or, alternatively, for a second system pressure p.sub.S2i equal to or less than the second limit pressure p.sub.Gbi, the time intervals ?t.sub.6i and ?t.sub.7i are defined or can be set on the control module (9) as a combined decompression time interval (?t.sub.6+?t.sub.7)i corresponding to a switching time in the form of a combined final decompression end step [(VI)+(VII)].

2. Rotary evaporator (1) according to claim 1, characterized in that the first limit pressure p.sub.Gai of step i is equal to the second limit pressure p.sub.Gbi of the same step i and thus corresponds to an equivalent limit pressure p.sub.Gi of step i (p.sub.Gai=p.sub.Gbi=p.sub.Gi).

3. Rotary evaporator (1) according to claim 1, characterized in that the control module (9) is designed and programmed to automatically carry out the decompression steps (III) to (VII) by manually triggering an decompression command at any time t.sub.1 with a first system pressure p.sub.S1i of an overall process, and the first system pressure p.sub.S1i is set equal to the second system pressure p.sub.S2i, wherein a time interval ?t.sub.5i can be preset on the control module (9) or can be selected by a switching duration of an actuated switching device (93) during execution of the decompression command, and wherein the time intervals ?t.sub.6i and ?t.sub.7i are each independent of one another and are each defined on the control module (9) as a switching time.

4. Rotary evaporator (1) according to claim 1, characterized in that the control module (9) is designed and programmed for the single and multiple automatic execution of subsequent process steps (I) and (II) as well as the decompression steps (III), (IV), (V), (VI) and (VII) in the specified sequence within a step i of n consecutive steps in each case within an overall process: (I) with the intermediate valve (7) closed, reducing an initial pressure p.sub.A or a second limit pressure p.sub.Gb(i?1) or an equivalent limit pressure p.sub.G(i?1) of the step (i?1) upstream the respective step i to a process pressure p.sub.Pi within a first time interval ?t.sub.1i, (II) with the intermediate valve (7) open, maintaining the process pressure p.sub.Pi for a second time interval ?t.sub.2i, (III) with the intermediate valve (7) open, reducing the process pressure p.sub.Pi to a first limit pressure p.sub.Gai or to an equivalent limit pressure p.sub.Gi within a third time interval ?t.sub.3i, (IV) with the intermediate valve (7) open, increasing the first limit pressure p.sub.Gai or the equivalent limit pressure p.sub.Gi to a holding pressure p.sub.Hi in a fourth time interval ?t.sub.4i, (V) with the intermediate valve (7) open, maintaining the holding pressure p.sub.Hi in a fifth time interval ?t.sub.5i, (VI) with the intermediate valve (7) open, reducing the holding pressure p.sub.Hi to a second limit pressure p.sub.Gbi or again to the equivalent limit pressure p.sub.Gi in a sixth time interval ?t.sub.6i and closing the intermediate valve (7) when the second limit pressure p.sub.Gbi or the equivalent limit pressure p.sub.Gi is reached, (VII) process step (I) starting from the second limit pressure p.sub.Gbi or the equivalent limit pressure p.sub.Gi followed by the process step (II) and the decompression steps (III) to (VII) in said sequence for the respective step (i+1) downstream of step i and, after passing through the last step (i=n), reducing the last second limit pressure G.sub.bn or the last equivalent limit pressure p.sub.Gn to a final pressure p.sub.E in a final time interval ?t.sub.E, where n corresponds to a natural number from 1 to the number of separable fractions of a liquid mixture, the initial pressure p.sub.A being adjustable or given by the atmospheric pressure on the control module (9) in each case, the final pressure p.sub.E being adjustable, the final time interval ?t.sub.E being adjustable or determinable as a switching time, each time interval t.sub.1i being adjustable or determinable or fixed as a switching time, and each process pressure p.sub.Pi and each time interval ?t.sub.2i being adjustable.

5. Rotary evaporator (1) according to claim 4, characterized in that the control module (9) for selective automatic execution of the decompression steps (VI) and (VII) is designed as a combined final decompression end step [(VI)+(VII)] for at least one step i or for all n steps i.

6. Rotary evaporator (1) according to claim 1, characterized in that the control module (9) is designed to set the temperature T.sub.V of the tempering bath (4) to a constant value or to a linear or gradually increasing course from an initial temperature T.sub.A to a final temperature T.sub.E.

7. Rotary evaporator (1) according to claim 1, characterized in that the intermediate valve (7) is designed as an electronically controllable solenoid valve, is connected to the condenser (5) via a flange connection or screw connection and either directly or via a distributor device (10) in each case via a detachable connection to each receiving flask (81, 82, 83).

8. Rotary evaporator (1) according to claim 1, characterized in that each receiving flask (81, 82, 83) can be vented via at least one end vent valve (74, 75), wherein each end vent valve (74, 75) is designed as an electronically controllable solenoid valve and wherein each end vent valve (74, 75) can be controlled autonomously with the control module.

9. Electronic control module (9) for the rotary evaporator (1) according to claim 1, designed for setting and automatically controlling subsequent control steps in the specified sequence: optionally: process step (I) with the subsequent process step (II), decompression step (III), decompression step (IV), decompression step (V), decompression step (VI), decompression step (VII).

10. Electronic control module (9) according to claim 9, characterized by a display (91) which is designed for setting, for displaying and optionally for graphically representing the control steps and optionally for graphically representing the course of the system pressure p.sub.S as a function of the time t with respect to the control steps carried out, the display (91) having a touch screen (92) for setting the control steps.

11. Method of fractional distillation of a liquid or a liquid mixture, which can be carried out automatically with the rotary evaporator (1) according to claim 1, characterized by the following process steps, which can be carried out in the specified sequence: process step (I), process step (II), decompression step (III), decompression step (IV), decompression step (V), decompression step (VI), readjustment step (VII).

Description

DESCRIPTION OF THE EMBODIMENTS

[0156] In the following, an embodiment example of the rotary evaporator according to the invention, which does not limit the invention, is explained in more detail with reference to figures. The figures show

[0157] FIG. 1A schematic representation of the rotary evaporator according to the invention with an intermediate valve with an output connection via a distribution manifold to three receiving flasks;

[0158] FIG. 2 the same rotary evaporator with an intermediate valve with two output connections to one receiving flask each;

[0159] FIG. 3 sections from a schematic system pressure-time diagram showing the execution of the decompression steps (III) to (VII) with the rotary evaporator under control with respect to a first limit pressure p.sub.Gai and a second limit pressure p.sub.Gbi;

[0160] FIG. 4 sections of a schematic system pressure-time diagram showing the execution of the decompression steps (III) to (VII) with the rotary evaporator under control with respect to an equivalent limit pressure p.sub.Gi;

[0161] FIG. 5 sections of a schematic system pressure-time diagram showing the execution of the decompression steps (III) to (VII) with the rotary evaporator under control with respect to an equivalent limit pressure p.sub.Gi i and with respect to combined steps (VI) and (VII) and thus a combined time interval (?t.sub.6+?t.sub.7)i;

[0162] FIG. 6 sections of a schematic system pressure-time diagram showing the execution of the decompression command with the rotary evaporator during an overall process;

[0163] FIG. 7 sections of a schematic system pressure-time diagram for drying a heterogeneous mixture of silica gel and chloroform with the rotary evaporator;

[0164] FIG. 8 sections from a schematic system pressure-time diagram of a distillation of a mixture of ethanol and toluene at a constant 40? C., which is carried out with the proposed rotary evaporator.

[0165] FIG. 1 and FIG. 2 schematically show the rotary evaporator 1. The rotary evaporator 1 has an evaporation flask 2, an electric motor 3, a temperature control bath 4, a condenser 5, an electric system pressure generator 6, an intermediate valve 7, several receiving flasks (81, 82, 83) and an electronic control module 9. FIG. 1 shows the rotary evaporator 1, which has an intermediate valve 7 with an inlet connection 71 and an outlet connection 72 to a distribution manifold 10, whereby the distribution manifold 10 is connected to three receiving flasks (81, 82, 83). FIG. 2 shows the same rotary evaporator 1, which has an intermediate valve with two output connections (72, 73) to one receiving flask (81, 82) each.

[0166] The evaporation flask 2 is designed as a glass flask with a volume of 2 L and is connected to a vapor tube 31 via a detachable ground joint. The vapor tube 31 is guided into the condenser 5 via a shaft seal. The shaft seal and thus the steam pipe 31 and consequently the evaporation flask 2 can be set in rotation by means of the electric motor 3. The steam pipe 31 is made of glass. The ground joint of the steam pipe 31 and the shaft seal are not shown in FIG. 1 and FIG. 2.

[0167] The electric temperature control bath 4 is designed to control the temperature of the evaporation flask 2 during operation of the rotary evaporator 1. For this purpose, the evaporation flask 2 is placed in the temperature control bath 4, whereby the temperature control bath 4 is filled with water as the temperature control medium and the water can be heated with an electric heater. The electric heater and the water as a temperature control medium are not shown in FIG. 1 and FIG. 2.

[0168] As an assembly, the condenser 5 has an internal cooling coil 51 as a cooling device, the shaft seal, a screw connection 52 to the system pressure generator 6 and a screw connection 53 to the intermediate valve 7. The internal volume of the condenser is 10 liters. The condenser 5 is made of glass except for the shaft seal. The shaft seal of the condenser 5 is not shown in FIG. 1 and FIG. 2.

[0169] A temperature-controlled cooling liquid can be circulated through the cooling spiral 51, for example by means of a circulation condenser connected to the cooling spiral 51 via hoses. During operation of the rotary evaporator 1, the cooling liquid is tempered to a lower temperature than the evaporation flask 2. A circulation condenser, connecting hoses and a coolant are not shown in FIG. 1 and FIG. 2.

[0170] The system pressure generator 6 has an electric vacuum diaphragm pump 61, an electrically controllable control valve 62, an electrically controllable vent valve 63 and an electronically readable pressure gauge 64. The system pressure p.sub.S can be measured with the pressure gauge 64, which is designed as a Pirani probe. The vacuum diaphragm pump 61 is connected to the control valve 62. The control valve 62, the aeration valve 63 and the pressure gauge 64 are connected to the condenser 5 via a common pipe connection 65. The control valve 62 and the ventilation valve 63 are each designed as an electric solenoid valve. The system pressure p.sub.S in the condenser 5, the evaporation flask 2 and, optionally via the intermediate valve 7, in the receiving flasks (81, 82, 83) can be adjusted with the control valve 62 and the vent valve 63. The control valve 62, the ventilation valve 63 and the intermediate valve 7 can each be controlled independently of each other. The direction of the arrow drawn on the system pressure generator 6 indicates the direction of flow of the gas conveyed from the evaporation flask 2 through the condenser 5 during operation of the rotary evaporator 1.

[0171] As an assembly, the intermediate valve 7 has an inlet connection 71, in FIG. 1 an outlet connection 72 with an end vent valve 74 and in FIG. 2 two outlet connections (72, 73) each with an end vent valve (74, 75). The intermediate valve 7 is designed as an electronically switchable solenoid valve. All end vent valves (74, 75) are also designed as electronically switchable solenoid valves. The end aeration valves (74, 75) are each electronically controllable independently of each other and independently of the intermediate valve 7, the aeration valve 63 and the control valve 62. The intermediate valve 7 is connected to the condenser 5 via the input connection 71, which is designed as a screw connection.

[0172] All receiving flasks (81, 82, 83) are each connected via a spherical ground joint either indirectly via the distribution manifold 10 to the output connection 72, as shown in FIG. 1, or directly to the output connections (72, 73) of the intermediate valve 7, as shown in FIG. 2. Each collection flask (81, 82, 83) can be vented via the associated end vent valve (74, 75). Each collection container is designed as a glass flask with an internal volume of 500 mL and is intended for collecting distillate.

[0173] In FIG. 1 and FIG. 2, a liquid mixture in the evaporation flask 2 and distillates in the collection flasks (81, 82, 83) are not shown.

[0174] The control module 9 has a display 91 as an assembly, whereby a touchscreen 92 is integrated on the display and a button 93 is integrated on the touchscreen 92. The control module 9 is connected via electrical control lines (110, 111, 112, 113, 114, 115, 116, 117, 118) to the vacuum diaphragm pump 61, the control valve 62, the vent valve 63, the pressure gauge 64, the intermediate valve 7 and its end vent valves (74, 75), the electric motor 3 and the temperature control bath 4. Electrical lines for the power supply of all electrically operable components and assemblies of the rotary evaporator are not shown in FIG. 1 and FIG. 2.

[0175] The control module 9 is thus designed to electronically control the system pressure generator 6, the intermediate valve 7 and its end vent valves (74, 75), the temperature control bath 4 and the rotational speed of the evaporation flask 2.

[0176] The control module 9 of the rotary evaporator 1 is designed to automatically perform the decompression steps (III) to (VII) once or several times by manual triggering by means of a button 93 as a decompression command at any time t1 at a system pressure pS1i of an overall process. The button 93 is located on the touchscreen 92. For this purpose, the touchscreen 92 of the control module is designed for manual input of the following parameters: [0177] first proportional factor f.sub.Gai for a first limit pressure p.sub.Gai and second proportional factor f.sub.Gbi for a second limit pressure p.sub.Gbi or alternatively equally selected proportional factor f.sub.Gi for an equivalent limit pressure p.sub.Gi, [0178] holding pressure factor f.sub.Hi for a holding pressure p.sub.Hi.

[0179] Thus, the first limit pressure p.sub.Gai can be determined by entering the first proportional factor f.sub.Gai and the second limit pressure p.sub.Gbi by entering the second proportional factor f.sub.Gbi or, alternatively, the equivalent limit pressure p.sub.Gi by entering the equivalent proportional factor f.sub.Gi and the holding pressure p.sub.Hi by entering the holding pressure factor f.sub.Hi, each as a product of the selected first system pressure p.sub.S1i with the respective factors f.sub.Gai, f.sub.Gbi, f.sub.Gi and f.sub.Hi.

[0180] By holding the switched button 93, a time interval ?t.sub.5i can be individually selected for the decompression step (V) after running through the decompression steps (III) and (IV) during execution of the decompression command. After releasing the switched button 93, the control module 9 is designed for the subsequent automatic execution of the decompression steps (VI) and (VII) and thus for the continuation of the overall process, whereby the time intervals ?t.sub.3i for the decompression step (III), ?t.sub.4i for the decompression step (IV), ?t.sub.6i for the decompression step (VI) and ?t.sub.7i for the decompression step (VII) are defined as switchover times on the control module 9 for the execution of the decompression command.

[0181] Furthermore, the control module 9 of the rotary evaporator 1 is for setting and automatically carrying out subsequent control steps of an overall process once or several times: [0182] process step (I), [0183] process step (II), [0184] decompression step (III), [0185] decompression step (IV), [0186] decompression step (V), [0187] decompression step (VI) and [0188] decompression step (VII)
are programmed and trained in the specified sequence. The setting of these control steps comprises the manual input of the following parameters for all n steps i on the touch screen 92: [0189] Initial pressure p.sub.A, [0190] Final pressure p.sub.E of the last step (i=n), [0191] End time interval ?t.sub.E as a value or switching time, [0192] first time segment ?t.sub.1i as value or switchover time, [0193] Process pressures p.sub.Pi with the assigned second time intervals ?t.sub.2i, [0194] common holding pressure factor f.sub.H, [0195] common first proportional factor f.sub.Ga and common second proportional factor f.sub.Gb for all steps i or alternatively common equally selected proportional factor fa for all steps i, individually adjustable fifth step time intervals for each step i ?t.sub.5i.

[0196] Thus, the holding pressures p.sub.Hi can be determined by entering a common holding pressure factor f.sub.H, the first limit pressures p.sub.Gai by entering the common first proportional factor f.sub.Ga and the second limit pressures p.sub.Gbi by entering the common second proportional factor f.sub.Gb or, alternatively, the equivalent limit pressures p.sub.Gi by entering the common equivalent proportional factor f.sub.G, each as a product of the individual process pressures p.sub.Pi with the respective factors f.sub.H, f.sub.Ga, f.sub.Gb and f.sub.G.

[0197] In addition, the control module 9 of the rotary evaporator 1 is designed for optional setting and automatic execution of the decompression steps (VI) and (VII) as a combined final decompression step [(VI)+(VII)] for at least one step i or for all n steps i. The setting of these end steps [(VI)+(VII)] additionally comprises the manual definition of subsequent parameters as switchover times on the touchscreen 92 for the steps i concerned: [0198] summarized decompression step time intervals (?t.sub.6(i?1)+?t.sub.1i), [0199] summarized end step time interval (?t.sub.6n+?t.sub.E).

[0200] On the touchscreen 92 and thus on the control module 9, the temperature T.sub.V of the temperature control bath 4 can also be set manually to a constant value or to a linear or gradual increase from an initial temperature T.sub.A to a final temperature T.sub.E.

[0201] The graphical representation of the entered control steps can be shown or called up in the form of a diagram on the display 91, whereby the diagram shows the course of the system pressure p.sub.S and the temperature T.sub.V of the temperature control bath 4 as a function of the time t and the diagram has labels with the set parameters and their values. The diagram is scaled with regard to the values of the temperature T.sub.V, the system pressure p.sub.S and the time. This diagram can be shown on the display in real time, stored on the control module 9 and subsequently called up on the display 91. In addition, the set parameters and their values can be displayed in the diagram. This diagram is also scaled with regard to the values of the temperature T.sub.V, the system pressure p.sub.S and the time.

[0202] The rotation speed of the evaporation flask 2 can also be controlled on the touchscreen 92. The set and current rotation speed can be called up and displayed on the display 92. In the diagram relating to the control steps carried out and the temperature curve, the rotational speed can be called up and displayed on the display 91 as a function of the time t using the touchscreen 92.

[0203] In the following sections, the respective relevant sections from the schematic system pressure-time diagrams of FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7 and FIG. 8 are described in more detail. For better illustration, relevant sections are shown enlarged by interrupting the axis. FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7 and FIG. 8 show the relevant decompression steps (III), (IV), (V), (VI), (VI) and [(VI)+(VII)], the corresponding time intervals ?t.sub.1i, ?t.sub.2i, ?t.sub.3i, ?t.sub.4i, ?t.sub.5i, ?t.sub.6i, ?t.sub.7i, ?t.sub.E and (?t.sub.6+?t.sub.7)i. The time periods ?t.sub.1i, ?t.sub.2i, ?t.sub.3i, ?t.sub.4i, ?t.sub.5i, ?t.sub.6i, ?t.sub.7i, ?t.sub.E and (?t.sub.6+?t.sub.7)i correspond to switching times in a range from 10.sup.?3 s to 1 s. Where relevant, the initial pressure p.sub.A, final pressure p.sub.E and the reference variables p.sub.s1i, p.sub.S2i, p.sub.Gai, p.sub.Gbi, p.sub.Gi, p.sub.Hi and p.sub.Pi are shown in FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7 and FIG. 8.

[0204] In FIG. 3, FIG. 4, FIG. 5 and FIG. 6, the first system pressure p.sub.S1i is 200 mbar and the holding pressure pHi is 240 mbar for a common holding pressure factor f.sub.H of 1.2 set on the touchscreen for FIG. 3, FIG. 4 and FIG. 5 and for a holding pressure factor f.sub.Hi of 1.2 set on the touch screen for FIG. 6. In FIG. 3, the first limit pressure p.sub.Gai is 180 mbar for a first common fraction factor f.sub.Ga of 0.9 set on the touch screen 92. In FIG. 4, FIG. 5 and FIG. 6, the equivalent limit pressure p.sub.Gi is also 180 mbar for a common equivalent proportional factor f.sub.G of 0.9 set on the touch screen for FIG. 3, FIG. 4 and FIG. 5 and for an equivalent proportional factor f.sub.Gi of 0.9 set on the touch screen. FIG. 3, FIG. 4, FIG. 5 and FIG. 6 are therefore comparable with each other and are each to be understood as an excerpt from an overall process, in which the decompression steps (III), (IV), (V), (VI) and [(VI)+(VII)] are illustrated. In each case, the holding pressure p.sub.Hi is higher than the first system pressure p.sub.S1i, higher than the first limit pressure p.sub.Gai in FIG. 3 and the second limit pressure p.sub.Gbi in FIG. 3 or than the equivalent limit pressure p.sub.Gi in FIG. 4, FIG. 5 and FIG. 6 and higher than the second system pressure p.sub.S2i. In FIG. 3, FIG. 4, FIG. 5 and FIG. 6, the decompression steps (III) to (V) are carried out with the intermediate valve 7 automatically open, during which the distillate remaining at the inlet connection of the intermediate valve 7 and in the condenser 5 is completely drained into the receiving flask 82. In FIG. 3, FIG. 4 and FIG. 5, the time interval ?t.sub.5i of 1 min set on the touchscreen 92 is sufficiently long for this purpose.

[0205] FIG. 3 shows sections of a schematic system pressure-time diagram, which include the automatic execution of the decompression steps (III) to (VII) with the rotary evaporator 1 under control with respect to a first limit pressure p.sub.Gai and a second limit pressure p.sub.Gbi of 190 mbar. A second proportional factor f.sub.Gbi of 0.95 is thus entered on the touch screen 92 for the second limit pressure p.sub.Gbi. Here, the first system pressure p.sub.S1i is greater than the second system pressure p.sub.S2i of 170 mbar and the first limit pressure p.sub.Gai is less than the second limit pressure p.sub.Gbi. In the decompression step (VI), the intermediate valve 7 is automatically closed when the second limit pressure p.sub.Gbi is reached. In the entire decompression step (VII) when the second system pressure p.sub.S2i is reached, the intermediate valve 7 is closed.

[0206] FIG. 4 shows sections of a schematic system pressure-time diagram showing the automatic execution of the decompression steps (III) to (VII) with the rotary evaporator 1 under control with respect to an equivalent limit pressure p.sub.Gi. Here, the first system pressure p.sub.S1i is lower than the second system pressure p.sub.S2i of 210 mbar. In the decompression step (VI), the intermediate valve 7 is automatically closed when the equivalent limit pressure p.sub.Gi is reached. In the entire decompression step (VII) when the second system pressure p.sub.S2i is reached, the intermediate valve 7 is closed.

[0207] FIG. 5 shows sections from a schematic system pressure-time diagram, which show the automatic execution of the decompression steps (III) to (VII) with the rotary evaporator 1 under control with respect to an equivalent limit pressure pGi and with respect to combined steps (VI) and (VII) and thus a combined time interval (?t.sub.6+?t.sub.7)i. For this purpose, the time intervals ?t.sub.3i and ?t.sub.7i were set on the touchscreen 92 as a combined decompression time interval (?t.sub.6+?t.sub.7)i corresponding to a switching time in the form of a combined final decompression end step [(VI)+(VII)]. In the combined time interval (?t.sub.6+?t.sub.7)i, the holding pressure p.sub.Hi, the equivalent limit pressure p.sub.Gi and the second system pressure p.sub.S2i of 170 mbar lie on a line in the system pressure-time diagram. This shows that the decompression steps (VI) and (VII) can be combined if the second system pressure p.sub.S2i is equal to or less than the equivalent limit pressure p.sub.Gi as shown in FIG. 5. In the decompression end step [(VI)+(VII)], the intermediate valve 7 is automatically open until the equivalent limit pressure p.sub.Gi is reached; when the equivalent limit pressure p.sub.Gi is reached, the intermediate valve 7 is automatically closed.

[0208] FIG. 6 shows sections of a schematic system pressure-time diagram showing the automatic execution of the decompression command with the rotary evaporator 1 during an overall process. The decompression command can be triggered or initiated manually with the button 93. Here, the first system pressure p.sub.S1i is equal to the second system pressure p.sub.S2i of 200 mbar and thus the second system pressure p.sub.S2i is greater than the equivalent limit pressure p.sub.Gi. Manual actuation of button 93 triggers the decompression steps (III) and (IV). By holding the switched button 93, a sufficiently long time interval ?t.sub.5i of 1 min is selected in FIG. 6 for the decompression step (V) until the distillate remaining at the inlet connection of the intermediate valve 7 and in the condenser 5 has completely flowed into the receiving flask 82. After releasing the switched button 93, the subsequent automatic execution of the decompression steps (VI) and (VII) is triggered by the control module 9. In decompression step (VI), the intermediate valve 7 is closed when the equivalent limit pressure p.sub.Gi is reached. In the entire decompression step (VII), when the second system pressure p.sub.S2i is reached, the intermediate valve 7 is automatically closed. After the decompression step (VII) has been carried out, the entire process is automatically continued by the rotary evaporator 1.

[0209] FIG. 7 shows sections of a schematic system pressure-time diagram for drying a heterogeneous mixture of silica gel and chloroform with the rotary evaporator 1 at a constant temperature T.sub.V of 40? over the entire time interval ?t.sub.ges of this overall process. For illustration purposes, the total time interval ?t.sub.ges is shown in FIG. 7. This is a one-step process (n=1), whereby the single step (i=1) comprises the control steps (I) to (VII).

[0210] In order to prevent the mixture from shooting through the rotary evaporator 1, the first time interval ?t.sub.11 in FIG. 7 is selected as a continuous pressure reduction or pressure ramp starting from an initial pressure p.sub.A of 1000 mbar to the process pressure p.sub.Pi of 45 min, which is sufficiently long to ensure complete outgassing of the mixture. In process step (I), the intermediate valve 7 is closed in order to ensure easier recovery of the mixture from the rotary evaporator 1 in the event of the mixture shooting through, to protect the intermediate valve 7 itself from contamination and to make it easier to clean the rotary evaporator 1.

[0211] In FIG. 7, in process step (II), the process pressure p.sub.P1 is set to the boiling pressure of chloroform at 470 mbar at 40? C., whereby the second time interval ?t.sub.21 of 90 min is selected on the touchscreen 92 to be sufficiently long to ensure that the chloroform evaporates as completely as possible. Here, the intermediate valve 7 is open in order to collect the chloroform in a receiving flask 82.

[0212] In FIG. 7, a common holding pressure factor f.sub.H of 1.021 for a holding pressure p.sub.H1 of 480 mbar and a common equally selected proportion factor f.sub.G of 0.979 for an equivalent limit pressure p.sub.G1 of 460 mbar are set on the touch screen 92 for the decompression steps (III) to (VI). The decompression steps (III) to (V) are carried out with the intermediate valve 7 open, during which the distillate remaining at the inlet connection 71 of the intermediate valve 7 and in the condenser 5 is completely drained off. The fifth time interval ?t.sub.51 of 2 minutes set on the touchscreen 92 is sufficiently long for this purpose. In the decompression step (VI), the intermediate valve 7 is closed when the equivalent limit pressure p.sub.G1 is reached.

[0213] Only after the residual portions of the condensed chloroform have been removed from the condenser 5 by means of the preset and automatically performed decompression steps (III) to (VI) can the silica gel remaining in the evaporation flask 2 be drawn dry in decompression step (VII). Since the receiving flask 82 is closed by the intermediate valve 7, the chloroform cannot boil back into the condenser 5 and excessive negative pressure in the receiving flask 81 itself is avoided. The collection flask 81 can be vented with the end vent valve 73. This also prevents an excessively high gas load of chloroform in the system pressure generator 6.

[0214] For the decompression step (VII) shown in FIG. 7, a final time interval ?t.sub.E of 120 min and a final pressure p.sub.E of 5 mbar are set on the touchscreen 92. The final time interval ?t.sub.E is selected to be sufficiently long so that with a continuous pressure reduction from the limit pressure p.sub.Gi to the final pressure P.sub.E, complete removal of chloroform from the silica gel can be realized without eruptive shooting of the silica gel into the condenser 5. In the decompression step (VII), the intermediate valve 7 is closed in order to ensure easier recovery of the silica gel from the rotary evaporator 1 if it shoots through, to protect the intermediate valve 7 itself from contamination and to make it easier to clean the rotary evaporator 1.

[0215] FIG. 8 shows sections of a schematic system pressure-time diagram of a distillation of a mixture of ethanol and toluene at a constant temperature T.sub.V of 40? over the entire time interval ?t.sub.ges of this overall process, which is carried out automatically with the proposed rotary evaporator 1. In FIG. 8, the total time interval ?t.sub.ges of this overall process is not shown. This is a two-step process (n=2). The first step (i=1) comprises the control steps (I) to (VI), whereby the decompression step (VII) that actually follows the decompression step (VI) corresponds to the process step (I) of the second step (i=2). The second step (i=2) thus comprises the control steps (I) to (VII). The intermediate valve 7 is automatically closed when process step (I) is carried out in the first (i=1) and in the second step (i=2) and is automatically open when process step (II) is carried out in the first (i=1) and in the second step (i=2), automatically opened when performing the decompression steps (III) to (V) in the first (i=1) and in the second step (i=2) and opened at the beginning when performing the decompression steps (VI) in the first (i=1) and in the second step (i=2) and closed when the respective equivalent limit pressures p.sub.G1 and p.sub.G2 are reached. When the decompression step (VII) is carried out in the second step (i=2), the intermediate valve 7 is closed.

[0216] For the distillation in FIG. 8, a common holding pressure factor f.sub.H of 1.2 for a holding pressure pH1 in the first step (i=1) and for a holding pressure pH2 in the second step (i=2) as well as a common equally selected proportion factor f.sub.G of 0.8 for an equivalent limit pressure p.sub.Gi in the first step (i=1) and for an equivalent limit pressure p.sub.G2 in the second step (i=2) are set on the touch screen 92 for the decompression steps (III) to (VI). Thus, the holding pressure pH1 and the equivalent limit pressure p.sub.G1 in the first step (i=1) as well as the holding pressure pH2 and the equivalent limit pressure p.sub.G2 in the second step (i=2) each have an equal size ratio of 1.5 to each other. With the decompression steps (III) to (VI), a complete removal of residual portions of condensed ethanol is realized in the first step (i=1) and a complete removal of residual portions of condensed toluene is realized in the second step (i=2) at the inlet connection 71 of the intermediate valve 7 and in the condenser 5.

[0217] In FIG. 8, a first time interval ?t.sub.11 of 20 min is selected for the process step (I) of the first step (i=1) of the distillation, starting from a set initial pressure p.sub.A of 1000 mbar on the touch screen 92, in order to achieve heating of the liquid mixture in the evaporation flask 2 to 40? C. A process pressure p.sub.P1 of 175 mbar is set on the touchscreen 92 for the first step (i=1), which corresponds to the boiling pressure of ethanol at 40? C. For the process step (II) of the first step (i=1), a second time interval ?t.sub.21 of 40 min is set to ensure complete distillation of ethanol into the first receiving flask 81. The final aeration valve 74 can be used to aerate the collection flask 81. For the decompression steps (III) to (VI) in the first step (i=1), the limit pressure p.sub.Gi is automatically set to 140 mbar by the control module 9 by means of the common equally selected proportion factor fa and the holding pressure p.sub.Hi is automatically set to 210 mbar by means of the common holding pressure factor f.sub.H.

[0218] For the process step (I) of the second step (i=2) of the distillation in FIG. 8, a first time interval ?t.sub.12 of 15 min is selected starting from the limit pressure p.sub.G1 of the first step (i=1) in order to realize the most complete possible removal of ethanol from the gas phase in the evaporation flask 2 and in the condenser 5. A process pressure p.sub.P2 of 77 mbar is set on the touchscreen 92 for the second step (i=2) of the distillation, which corresponds to the boiling pressure of toluene at 40? C. For the process step (II) of the second step (i=2), a second time interval ?t.sub.22 of 60 min is set to ensure complete distillation of toluene into the second receiving flask 82. The collection flask 82 can be vented with the final vent valve 75. For the decompression steps (II) to (VI) in the second step (i=2), the limit pressure pG2 is automatically set to 62 mbar by the control module 9 by means of the common equally selected proportion factor fG and the holding pressure p.sub.H2 is automatically set to 92 mbar by means of the common holding pressure factor f.sub.H.

[0219] The decompression step (VII) of the second step (i=2) in FIG. 8 comprises the reduction of the limit pressure p.sub.G2 to the final pressure p.sub.E of 10 mbar set on the touchscreen 92. For this purpose, an end time interval ?t.sub.E of 5 min is set on the touchscreen 92.

[0220] By closing the intermediate valve 7 after the process steps (II) and the decompression steps (III) to (VII) have been carried out, ethanol is prevented from boiling back out of the collection flask 81 and toluene from the collection flask 82 into the condenser 5 and a high vacuum is prevented in the collection flasks (81, 82).

LIST OF REFERENCE SYMBOLS

[0221] 1 Rotary evaporator [0222] 2 Evaporation flask [0223] 3 Electric motor [0224] 31 Steam pipe [0225] 4 Tempering bath [0226] 5 Condenser [0227] 51 Cooling coil [0228] 52 Screw connection [0229] 53 Screw connection [0230] 6 System pressure generator [0231] 61 Vacuum diaphragm pump [0232] 62 Control valve [0233] 63 Vent valve [0234] 64 Pressure gauge [0235] 65 Pipe connection [0236] 7 Intermediate valve [0237] 71 Inlet connection [0238] 72 Outlet connection [0239] 73 Outlet connection [0240] 74 End vent valve [0241] 75 End vent valve [0242] 81 Receiving flask [0243] 82 Receiving flask [0244] 83 Collector flask [0245] 9 Electronic control module [0246] 91 Display [0247] 92 Touch screen [0248] 93 Button [0249] 10 Distribution manifold [0250] 110 Electrical control line from control module 9 to vacuum diaphragm pump 61 [0251] 111 Electrical control line from control module 9 to control valve 62 [0252] 112 Electrical control line from control module 9 to the ventilation valve 63 [0253] 113 Electrical control line from control module 9 to pressure gauge 64 [0254] 114 Electrical control line from control module 9 to intermediate valve 7 [0255] 115 Electrical control line from control module 9 to final aeration valve 74 [0256] 116 Electrical control line from control module 9 to end vent valve 75 [0257] 117 Electrical control line from control module 9 to electric motor 3 [0258] 118 Electrical control line from the control module 9 to the temperature control bath 4