Methods for determining the boiling point of a liquid mixture and rotary evaporators with a flow sensor

Abstract

The invention generally proposes a method (100) for determining (105) a boiling point (21) of a liquid mixture (4) located in an evaporator flask (3) of a rotary evaporator (1), wherein a heating bath (10) into which the evaporator flask (3) is immersed is heated (101), wherein a pump (6) generating a vacuum is switched on (102), so that a gas (8) released from the liquid mixture (4) as a result of the heating (101) and / or the vacuum flows out of the evaporator flask (3) (103), characterized in that a profile (20) of a flow parameter (11) of the flowing gas (8) is detected (104) and that the boiling point (21) of the liquid mixture (4) is determined (105) by automatically processing the detected (104) profile (20) of the flow parameter (11). evaluated (106). Furthermore, a rotary evaporator (1), a measuring device (12) and a method (200) for controlling the rotary evaporator (1) are proposed.

Description

[0001] The invention relates to a method for detecting a boiling point of a liquid mixture of substances which is located in an evaporation flask of a rotary evaporator, wherein a heating bath into which the evaporation flask is immersed is heated, wherein a pump which generates a negative pressure is switched on, so that a gas released from the liquid mixture of substances as a result of the heating and / or the negative pressure flows out of the evaporation flask.

[0002] The boiling point refers to the state conditions under which the mixture of substances is at the point that marks the transition from non-boiling to boiling or from boiling to non-boiling state. For example, at the boiling point, an increase in temperature and / or a decrease in pressure can bring the mixture of substances to a boiling state. For this to happen, it is sufficient that one component of the mixture is brought to a boiling state. The boiling point of a liquid mixture therefore means that at least one component of the mixture is at its boiling point. It should be noted that, under otherwise identical conditions, the boiling point of a component in the mixture can differ from the boiling point that the component has when isolated from the mixture.

[0003] The invention further relates to a rotary evaporator comprising a container for a heating bath, an evaporator flask rotatable within the container, a condenser, a collecting flask for receiving condensate from the condenser, a sensor, and a pump. The pump can be used to form a flow path for a gas flowing out of the evaporator flask between the evaporator flask and the pump. As described above, the rotary evaporator comprises a sensor and thus precisely one or more than one sensor.

[0004] Rotary evaporators are used to separate at least two components of a liquid mixture. As described above, the liquid mixture, which is located in the evaporating flask that rotates about its longitudinal axis, is immersed in the heating bath and heated. Separation of the at least two components of the liquid mixture is achieved when their boiling points, in particular their boiling temperatures and / or boiling pressures, differ. For optimal separation of the at least two components, the point in time at which the boiling point of one of the at least two components is reached must be detected. If this point in time is not detected, the mixture may, for example, foam over.

[0005] To reliably determine the boiling point, the operator often manually observes the liquid mixture. This involves observing bubbles and / or vapor formation in the liquid mixture in the evaporation flask. While the boiling point detection rate is relatively high, this method is very time-consuming and therefore costly. Furthermore, the manual method poses a risk to the operator, especially when a rotary evaporator is operated under negative pressure.

[0006] Automated detection methods are also known from the state of the art. For example, boiling point detection involves performing a pressure measurement, comparing it with a previously known pressure curve, and then drawing conclusions about whether or not a boiling point has been reached. Such methods have the disadvantage that previously known measurement curves must be stored. Furthermore, the detection rate of these methods is very low.

[0007] Another method used in practice analyzes the inlet and outlet temperatures of the cooling water in the condenser. Condensation adds energy to the cooling water, causing the cooling water temperature to rise. A boiling point can be identified based on the cooling water temperature rise between the inlet and outlet of the cooling water channel in the condenser. This method is more suitable for adjusting condenser utilization than for identifying the actual onset of boiling.

[0008] Another method used in practice analyzes the gas temperature in the flow path between the evaporator flask and the condenser. When boiling begins, heated gas flows through the water bath along this flow path. This causes the gas temperature in the flow path to rise, and the boiling point is identified. The disadvantage of this method is that boiling points are very uncertain when the water bath temperature is close to ambient temperature. In this situation, the gas temperature in the flow path is not elevated when boiling begins, and thus can only be identified with uncertainty based on the gas temperature.

[0009] The invention further relates to a measuring device for a rotary evaporator, a use of the flow sensor and a use of a measuring device in a rotary evaporator.

[0010] Finally, the invention relates to a method for controlling a rotary evaporator as described herein.

[0011] The object of the invention is to improve the separation of components in a liquid mixture. In particular, the detection of the boiling point of the liquid mixture is to be improved.

[0012] To achieve the stated object, the features of claim 1 are provided according to the invention. In particular, to achieve the stated object, in a method of the type described above, the invention proposes that a profile of a flow parameter of the flowing gas be recorded and that the boiling point of the liquid mixture be detected by automatically evaluating the recorded profile of the flow parameter. "Profile" refers to a temporal profile. "Automated evaluation" refers to an evaluation based on an algorithm. The evaluation is preferably computer-assisted.

[0013] The flow parameter describes a physical quantity related to the flow of the flowing gas. This can be a volume flow, a mass, a flow rate, a flow velocity, or an equivalent physical property of the flowing gas.

[0014] The invention has recognized that by detecting the course of a flow parameter, changes in a flow parameter of the released gas can advantageously be detected, whereby the boiling point of the liquid mixture can be evaluated automatically.

[0015] The recording of the course of the flow parameter comprises a recording of at least one flow parameter of the gas.

[0016] The recording of the course of the flow parameter includes a period in which negative pressure is generated by the pump, whereby the generation of a negative pressure includes maintaining the negative pressure.

[0017] Heating the heating bath here means heating a liquid, which is preferably located in a container as described herein. Water or oil are preferred liquids. The heating bath can be heated by a heating element as described herein, for example, energizable heating coils. Thus, a temperature for heating the heating bath can advantageously be set and / or regulated.

[0018] The boiling point of the liquid mixture here refers in particular to the boiling point of a first component of the liquid mixture, wherein the boiling point of the first component differs from the boiling point of at least one second component of the liquid mixture. The first component is a liquid. Other components of the liquid mixture can be liquids and / or solids, with solids being dissolved in the liquid.

[0019] The boiling point of components can be advantageously reduced by the negative pressure generated by the switched-on pump, so that even components that have a relatively high boiling point at the prevailing ambient pressure (which is often around 1,000 mbar) can be separated from one another in a liquid mixture. The pump can be a negative pressure pump, preferably a vacuum pump.

[0020] Thanks to the automated evaluation, subjective observations by a user are no longer necessary to detect the boiling point.

[0021] The automated evaluation of the course of the flow parameter and thus the detection of the boiling point in the method according to the invention can be carried out using an algorithm which does not require stored pressure curves and / or other parameter curves for specific substance mixtures.

[0022] Any characteristics of the flow parameter profile, for example, a rapid increase (which can be defined, for example, by exceeding a value of an angle of rise or by exceeding a value of a change in the detected flow parameter in a predetermined time period) of a flow parameter of the gas, can be automatically evaluated by the algorithm to detect the boiling point. Particularly preferably, the automated evaluation is carried out by a computing unit, in particular the one described and / or claimed below.

[0023] Thus, the boiling point detection can be carried out very accurately and reproducibly with a very high detection rate.

[0024] In particular, it can be provided that the evaluation of the course of the flow parameter comprises determining a value of a change in the detected flow parameter in a predetermined time period, and that the boiling point is detected by determining that a predetermined change value is exceeded.

[0025] The method according to the invention detects the boiling point of the liquid mixture very accurately, even when the mixing ratio in the liquid mixture changes due to the progressive release of the gas. This allows the separation of components in a liquid mixture to be significantly improved.

[0026] The course of the flow parameter is characterized in that it comprises at least two values ​​of the flow parameter at different points in time. The course of the flow parameter thus comprises at least two values ​​of the flow parameter of the gas at two different points in time. However, the respective course preferably comprises a plurality of values. A plurality of values ​​is present when there are at least 10 values. The values ​​are particularly preferably recorded at equidistant and / or predetermined and / or known points in time. The recording of the respective flow parameter is particularly preferably carried out continuously, so that a continuous parameter course is present.

[0027] In an advantageous embodiment of the method, it can therefore be provided that a flow parameter of the flowing gas is recorded at multiple points in time. Recording the flow parameter of the flowing gas enables the recording of the course of the flow parameter, particularly if the flow parameter is measured or recorded at multiple points in time, as may be provided.

[0028] Preferably, it can be provided that the flow parameter is recorded at a plurality of regularly spaced points in time.

[0029] Alternatively or additionally, the flow parameter can be recorded continuously. This allows the flow parameter of the flowing gas to be measured without any interruption, advantageously allowing a continuous flow parameter profile to be recorded. This allows the boiling point to be determined with particular precision.

[0030] In an advantageous embodiment of the method, it can be provided that a temperature profile of the gas is recorded and that the boiling point of the liquid mixture is detected by automatically evaluating the recorded temperature profile. By recording the temperature profile in addition to the profile of the flow parameter, the boiling point can be detected even more precisely. The two profiles can, in particular, be incorporated as input parameters in a common calculation rule in which a single value is calculated. Alternatively, the aforementioned profiles can also be used to obtain two or more values. These can then be combined to form a value with greater accuracy. Alternatively, by comparing the values, a key figure can be determined which evaluates the reliability of the value determined from the profile of the flow parameter.

[0031] The advantages just described are even more pronounced if, as may be provided in particular, a temperature profile of the gas is recorded. For this purpose, in particular, a continuous recording of the gas temperature is carried out over the same period in which a recording of the flow parameter described herein is carried out. Thus, the flow parameter and the temperature profile can advantageously be automatically evaluated over the same period in order to determine the boiling point.

[0032] In an advantageous embodiment of the method, it can be provided that a total pressure is recorded. Total pressure here refers to the pressure prevailing in the rotary evaporator. Recording the total pressure can be advantageous when the total pressure needs to be regulated due to changes in a system parameter of the rotary evaporator. For example, it can be provided that the total pressure is maintained when the flow parameter has reached a certain value and / or when the boiling point has been reached. Recording the total pressure is also advantageous for monitoring and / or regulating the functionality of the pump that generates the negative pressure.

[0033] Alternatively or additionally, a static pressure can be measured. This is particularly advantageous if, as may advantageously be provided, the dynamic pressure is to be determined. The static pressure is measured, in particular, at a specific point in a gas flow path, in particular the flow path described herein.

[0034] In particular, by measuring the total pressure and / or by determining the dynamic pressure, flow properties of the flowing gas can be recorded, which allows the detection of the boiling point to be particularly accurate, especially when the mixing ratio of the liquid mixture changes.

[0035] It can be provided that a pressure profile of the total pressure and / or the static pressure and / or the dynamic pressure is / are recorded. This can advantageously be compared with the flow parameter profile described herein and / or the temperature profile described herein. As can be provided, this can particularly advantageously control and / or regulate at least one system parameter of a rotary evaporator, in particular of the type described herein, thereby enabling optimal separation of components in a liquid mixture.

[0036] It is then preferably provided that the boiling point of the liquid substance mixture is detected by automatically evaluating the detected total pressure and / or the detected static pressure and / or the determined dynamic pressure and / or the previously mentioned pressure curve.

[0037] In particular, the following system parameters can be provided: a temperature of the heating bath, the total pressure and / or the speed of the evaporator flask.

[0038] Alternatively or additionally, the features of the independent claim directed to a rotary evaporator are provided according to the invention to achieve the stated object. In particular, to achieve the stated object in a rotary evaporator of the type described above, the invention proposes that the sensor be a flow sensor with which a flow parameter of the gas can be measured, and that the sensor be arranged in the flow path. Therefore, the flow sensor can measure precisely one or more than one flow parameter of the gas. The flow sensor can be an anemometer or any other type of sensor with which a flow parameter of the gas can be measured.

[0039] The flow sensor can advantageously detect a volume flow, a mass, a flow rate, a flow velocity, or an equivalent physical property of the gas flowing in the flow path. Thus, a profile of the flow parameter, in particular one as described herein, can be detected in order to detect a boiling point of the liquid mixture.

[0040] Arranged in the flow path means that the flow sensor is arranged such that it is sensitive in the flow path. The flow path of the flowing gas comprises at least one region within the rotary evaporator according to the invention, which is formed between the pump connection on the rotary evaporator and the evaporator flask and / or between a condenser flask of the condenser and the evaporator flask.

[0041] The flowing gas flows into the condenser and condenses there, so that the majority of the gas is not pumped out. The flow parameters, such as the flow velocity, flow rate, and / or volumetric flow rate, of the gas therefore weaken in the condenser. Therefore, the flow sensor is particularly preferably arranged in the flow path between an end of the condenser facing the evaporator flask and the evaporator flask. This allows a particularly precise recording of the flow parameter profile, which enables the exact identification of the boiling point.

[0042] It can also be provided that more than one flow sensor is arranged in the flow path. Preferably, the flow sensors are arranged at spatial distances within the flow path. Spatially spaced means that the presence of one flow sensor in the flow path has no influence on flow parameters detected by another flow sensor in the flow path. By arranging multiple flow sensors, multiple profiles of the flow parameter(s) can be recorded to detect the boiling point.

[0043] In an advantageous embodiment, the rotary evaporator can be configured to carry out a method according to the invention for detecting the boiling point of a liquid mixture, as claimed or described herein. Thus, a user can carry out the method according to the invention, along with the associated advantages, in particular those described above, using the rotary evaporator.

[0044] In an advantageous embodiment, the rotary evaporator can be provided with a flow line connecting the condenser and the evaporator flask. The flow line is preferably detachably connectable to the condenser and the evaporator flask, particularly if the flow line is formed by a measuring device as described herein. The flow path can be formed by the flow line, so that the flow sensor can advantageously be arranged in the flow line.

[0045] In particular, the flow line or a section of the flow line can be formed by a measuring device described herein. For example, the flow line can be formed by the pipe of the measuring device described herein. In this particularly advantageous embodiment, the flow sensor and / or a temperature sensor and the flow line can be mounted on the rotary evaporator simultaneously and in a space-saving manner.

[0046] Alternatively or additionally, the features of the independent claim directed to a measuring device are provided according to the invention to achieve the stated object. In particular, to achieve the stated object, the invention proposes that a measuring device of the type described above comprise: a flow sensor with which a flow parameter of a gas can be detected, a pipe section into which the flow sensor is inserted, and two flanges, each flange being formed at an open end of the pipe section.

[0047] The measuring device can be detachably connected to the rotary evaporator so that the measuring device can be conveniently replaced for maintenance and / or repairs.

[0048] Furthermore, the measuring device can have at least one electrical connecting cable.

[0049] The electrical connecting cable can be designed as a power cable. Thus, the measuring device, in particular the flow sensor, can be supplied with electrical power.

[0050] The electrical connection cable can alternatively or additionally be designed as a signal cable. A signal received by the flow sensor can be transmitted via the signal cable, for example, to a processing unit. In this case, the electrical connection cable can serve as an interface for signal transmission between the measuring device and the rotary evaporator, in particular its pump.

[0051] If a computing unit is arranged in or on a housing of the measuring device, the connecting cable can also be designed as a digital signal connection between the computing unit and the control unit of the rotary evaporator, in particular a control unit of the pump.

[0052] The pump of the rotary evaporator can have a control unit for regulating the negative pressure generated by the pump. The rotary evaporator can have one or more control units with which a temperature of the heating bath and / or a rotational speed of the evaporation flask can be regulated. At least one system parameter of the rotary evaporator, in particular its pump, can be controlled by means of the control unit or control units, in particular those described above.

[0053] The processing unit and the control unit can form a common module. The control unit and the processing unit can also be spatially separated and connected to each other via a signal cable, preferably a digital one.

[0054] In an advantageous embodiment, it can be provided that the measuring device comprises a computing unit which is configured to automatically evaluate a profile of the flow parameter of the gas detected by the flow sensor. The computing unit can thus detect the boiling point of the liquid mixture. The computing unit can be arranged in or on a housing of the measuring device, but is preferably spatially separate and connected to the flow sensor via an electrical connecting cable, for example the aforementioned connecting cable. The computing unit can be a stand-alone component. The computing unit can also be a computing unit of the rotary evaporator, in particular a computing unit of the pump. This can preferably be a computing unit which also controls the pump. The computing unit can be arranged in or on the pump housing.

[0055] In an advantageous embodiment, it can be provided that the rotary evaporator, in particular the pump of the rotary evaporator, and / or the measuring device comprises at least one pressure sensor, with which a pressure development in the rotary evaporator can advantageously be monitored. It can also be provided that the pressure sensor and the data acquired thereby create a pressure curve, which can be automatically evaluated to regulate system parameters of the rotary evaporator and / or to detect the boiling point of the liquid mixture.

[0056] Alternatively or additionally, the measuring device may comprise a temperature sensor with which the temperature of the flowing gas can be detected. By detecting the temperature of the flowing gas, the boiling point can be detected even more precisely, particularly if a temperature profile as described herein is detected.

[0057] Alternatively or additionally, to achieve the stated object, the features of the independent claim directed to a use of a flow sensor are provided according to the invention. In particular, to achieve the stated object, it is proposed that a flow sensor be used to detect a flow parameter of a gas flowing in a rotary evaporator. As described above, the invention has recognized that the detection of a flow parameter of the flowing gas can be used particularly advantageously to detect the boiling point of the liquid substance mixture. Thus, the use of the flow sensor according to the invention is particularly advantageous in a method described herein and / or a rotary evaporator described herein and / or in a measuring device described herein.

[0058] Alternatively or additionally, the features of the independent claim directed to the use of a measuring device in a rotary evaporator are provided according to the invention to achieve the stated object. In particular, it is proposed to achieve the stated object in the mentioned use that a measuring device as described and / or claimed herein be used. This allows for particularly precise detection of a boiling point in a rotary evaporator, thereby improving the separation of components of a liquid mixture.

[0059] Alternatively or additionally, the features of the independent claim directed to a method for controlling a rotary evaporator are provided according to the invention to achieve the stated object. In particular, to achieve the stated object, it is proposed in the method of the type described above that a boiling point of a liquid mixture of substances located in the evaporation flask of the rotary evaporator be detected by means of a method for detecting a boiling point of a liquid mixture of substances as described herein, and that this triggers a control signal with which a system parameter of the rotary evaporator is regulated.

[0060] The system parameter can be, for example, a total pressure prevailing in the rotary evaporator, such as the total pressure already mentioned above, a temperature of the heating bath and / or a speed of the rotating evaporator flask.

[0061] To detect the boiling point, a measurement signal can be recorded using the flow sensor. The measurement signal can represent a profile of the flow parameter of the flowing gas. The measurement signal can then be transmitted, in particular via an electrical connecting cable, to a computing unit, which can be designed and arranged as described above. The boiling point of the liquid mixture can then be recorded in the computing unit through computer-assisted evaluation of the profile of the flow parameter.

[0062] If the processing unit detects a boiling point, it can trigger a control signal, which is then sent via a signal connection to a control unit of the pump and / or to another control unit of the rotary evaporator. The pump control unit can then regulate the generated negative pressure, for example, so that the reached pressure is no longer reduced but is maintained. Alternatively or additionally, the additional control unit of the rotary evaporator can regulate the temperature of the heating bath so that the temperature is no longer increased but is kept constant. Alternatively or additionally, the rotational speed of the evaporation flask can also be regulated so that the boiling point is maintained. This therefore regulates at least one system parameter of the rotary evaporator.

[0063] Controlling at least one system parameter of the rotary evaporator is particularly advantageous when the mixing ratio of the at least two components of the liquid mixture changes during the separation process and / or when the conditions for reaching the boiling point in the rotary evaporator change. By controlling the rotary evaporator, these changes can be counteracted, allowing the separation of the at least two components of the liquid mixture to be optimally adjusted or carried out.

[0064] In particular, the total pressure of the rotary evaporator can be controlled. For example, it can be provided that the control unit controls and regulates the pump described herein to maintain or reduce the total pressure in the rotary evaporator. For example, it can advantageously be provided that when the boiling point is reached and detected, the computing unit transmits this information to the control unit, whereupon the control unit controls the pump so that the total pressure in the rotary evaporator is maintained.

[0065] The control includes in particular: the regulation of the heating bath temperature, the change of the pump speed and / or the speed of the rotating evaporator flask.

[0066] The invention will now be described in more detail using exemplary embodiments, but is not limited to these exemplary embodiments. Further exemplary embodiments arise from combining the features of individual or multiple claims with one another and / or with individual or multiple features of the exemplary embodiments.

[0067] It shows: Fig. 1 a rotary evaporator according to the invention with a measuring device according to the invention, Fig. 2 a side view of the measuring device Fig. 1, Fig. 3 the measuring device Fig. 2 as a sectional drawing, Fig. 4 a method according to the invention for detecting a boiling point of a liquid mixture using the Fig. 1 shown rotary evaporator, Fig. 5 shows a method according to the invention for controlling the rotary evaporator from Fig. 1, Fig. 6 a recorded course of a flow parameter during the process Fig. 4.

[0068] Fig. Figure 1 shows a rotary evaporator 1 in operation, which comprises a container 2 filled with a heating bath 10. The heating bath 10 is water or oil. Furthermore, the rotary evaporator 1 has a rotatable evaporation flask 3 containing the liquid mixture 4. The rotatable evaporation flask 3 is immersed in the heating bath 10 and can be rotated about its longitudinal axis within the heating bath 10. The heating bath 10 is heated by a heating element 30.

[0069] The rotary evaporator 1 further comprises a condenser 33 supplied with cooling water and / or another cooling liquid to form a cooling surface on which a gas 7 flowing in a flow path 8 precipitates, forming a condensate of the gas 7 that can flow into the collecting flask 34. The flow path 8 is formed between the evaporator flask 3 and a pump 6, since the negative pressure generated by the pump 6 causes the gas 7 released in the evaporator flask 3 to flow out of the evaporator flask 3. The pump 6 comprises a control unit 35 with which the negative pressure generated by the pump 6 can be controlled.

[0070] Furthermore, Fig. 1 that the rotary evaporator has a flow line 32 connecting the condenser 33 and the evaporator flask 3, wherein the flow line 32 is formed by a Fig. 2 and Fig. 3. The flow line 32 is formed by the pipe 13 of the measuring device 12. The flow path 7 can be formed or is formed in the pipe 13, 32, so that a sensor 5, which is a flow sensor 9, is optimally positioned in the flow path 8 such that a flow parameter 11 of the flowing gas 7, such as a flow velocity, a flow rate, a volume flow, or another equivalent physical property of the flowing gas, is detected by the sensor 5, 9.

[0071] The measuring device 12 is connected to the pipe section 13 via two flanges 14a, 14b, which are formed at the open ends of the pipe section 13 (cf. Fig. 2 and Fig. 3), is tightly connected to the condenser 33 and the evaporator flask 3. Thus, no gas 7 can flow out of the rotary evaporator 1.

[0072] As shown in the sectional view of the measuring device 12 in Fig. As can be seen in Figure 3, the sensor 5, 9, 27 is inserted into an interior space 16 of the pipe section 13. The part of the sensor 5, 9, 27 located outside the pipe section 13 is surrounded by a housing 18 of the measuring device 12 and protected from external influences. The housing 18 supporting the sensor 5, 9, 27 is connected to the pipe section 13 by a positive and non-positive connection. A positive and non-positive connection can be achieved, for example, by a thread 19.

[0073] The computing unit 26 is configured to evaluate 106 the flow parameters 11 of the gas 8 detected by the flow sensor 5, 9, 27 in step 104 in an automated manner, ie with computer support.

[0074] The measuring device 12 further comprises a computing unit 26, which is configured to automatically, i.e., computer-assisted, evaluate 106 the flow parameters 11 of the gas 8 detected by the flow sensor 5, 9, 27. The computing unit 26 is spatially separated from the built-in part of the measuring device 12, which includes the pipe section 13. In an alternative embodiment, the computing unit 26 is provided by the control unit 35 of the pump 6.

[0075] Furthermore, the measuring device 12 has at least one electrical connecting cable 17. The Fig. 1, Fig. 2 and Fig. The electrical connecting cable 17 shown in Figure 3 serves as an interface for signal transmission 201 between the flow sensor 9 and the computing unit 26. The computing unit 26 is signal-connected to the control unit 31 of the rotary evaporator 1 and / or to the control unit 35 of the pump 6. Thus, system parameters of the rotary evaporator 1, in particular of its pump 6, can be controlled by the control units 31, 35 according to the Fig. 5 procedures.

[0076] In an embodiment not shown, the or another electrical connecting cable serves to supply the sensor 5, 9, 27 with electrical current.

[0077] In Fig. 3 further shows that the measuring device 12 has a temperature sensor 29. In an alternative embodiment of the measuring device 12, it does not have a temperature sensor 29.

[0078] The following describes how a method 100 for detecting a boiling point 21 of the liquid mixture 4 can be carried out using the previously described rotary evaporator 1 and the measuring device 12 used therein. The method 100 is shown in Fig. 4 illustrated.

[0079] First, the liquid mixture 4, which consists of two components with different boiling points, is transferred into the evaporation flask 3 of the rotary evaporator 1. The evaporation flask 3 is then immersed in the heating bath 10 and rotated around its longitudinal axis.

[0080] In step 101, the heating element 30 heats the heating bath 10 located in the container 2.

[0081] Before or during heating 101, pump 6 is switched on in step 102, creating a negative pressure in rotary evaporator 1. As a result of the switching on 102 of pump 6 and the resulting negative pressure, as well as the heating, the liquid mixture 4 approaches boiling point 21. Once boiling point 21 is reached, the liquid mixture 4 begins to boil, and the released gas 9 flows out of evaporator flask 3 in step 103.

[0082] As a result of the flow of the gas 8, the flow path 7 of the gas 8 is now formed between the connection of the pump 6 on the rotary evaporator 1 and the liquid level of the liquid mixture 4 located in the evaporator flask 3.

[0083] The flowing gas 8 flows through the pipe 13, 32 of the measuring device 12 of the rotary evaporator 1. The flow sensor 5, 9, 27 detects in step 104 a temporal profile 20 of a flow parameter 11 of the flowing gas 8 by continuously detecting the flow parameter 11 of the gas 8. An exemplary profile 20 of the flow parameter 11 is shown in Fig. 6 shown.

[0084] The computing unit 26 of the measuring device 12 automatically evaluates the recorded profile 20 of the flow parameter 11 in step 105 using an algorithm and then detects the boiling point 21 of the liquid substance mixture 4 in step 106.

[0085] Furthermore, a temperature profile 22 is recorded 107 at the same time as the profile 20 of the flow parameter is recorded 104 by the temperature sensor 29. Likewise, in step 108, the total pressure 23 is recorded by the pressure sensor 28, which is preferably integrated in the pump 6. A pressure profile is recorded, which is automatically evaluated together with the temperature profile 22 and the profile 20 of the flow parameter 11 to identify the boiling point 21. Steps 101 to 108 do not have to follow one another chronologically, but can also be performed in a different order, in particular simultaneously. Thus, the separation of the components of the liquid mixture 4 is improved, in particular since system parameters of the rotary evaporator 1 can be controlled based on the recorded temporal profiles 20, 22, 24 by the method 200 for controlling a rotary evaporator 1 described below, see also Fig. 5.

[0086] The method 200 comprises, in a first step, a method 100 for detecting a boiling point 21, which has been described in more detail above, see also Fig. 4. If a boiling point is detected, a control signal is triggered in step 201, which is then used to regulate a system parameter, in particular a total pressure 23, of the rotary evaporator 1 in step 202. The control signal is triggered in the processing unit 26 and sent to the control unit 31 of the rotary evaporator 1 and to the control unit 35 of the pump 35. If the control unit 35 receives a control signal indicating the detection of the boiling point, the negative pressure generated by the pump 6 is maintained at a constant value by means of the control unit 35. The control unit 31 regulates accordingly to keep the heating bath temperature and / or the speed of the rotary evaporator constant.

[0087] For this purpose, as a result of the flow parameter 11 of the gas 8 detected by the method 100 and / or the detected 105 boiling point 21, a signal transmission 201 is carried out by the computing unit 26 of the rotary evaporator 1 to the control unit 31 of the rotary evaporator 1, whereupon the control unit 31 controls 202 the total pressure 23 of the rotary evaporator 1. To control the total pressure 23, the power of the pump 6 is controlled.

[0088] The gas 8 flows into the condenser 33, where it is condensed and flows into the collecting flask 34. Thus, a complete separation of the at least two components of the liquid mixture 4 is improved by the rotary evaporator 1 with measuring device 12 and the methods 100 and 200.

[0089] Fig. 6 shows a real test according to the previously described procedure 100 and 200 (cf. Fig. 4 and Fig. 5) measured curve 20 of a flow parameter, which represents the voltage signal generated by the flow sensor and is thus equivalent to, among other things, the flow velocity, the flow rate and the flowing volume flow. To understand the Fig. 6: U describes the voltage signal of the flow sensor 9 in volts, the pressure curve 24 is the total pressure 23 given as p in mbar, the temperature curve 22 is the temperature of the gas 8 in the rotary evaporator 2 given as t in °C and the acquisition time t of the curves 20, 22 and 24 is given in seconds s. Fig.6 shows a steep rise in the curve 20 of the flow parameter 11 or the flow parameter 11 after second 60. This rise correlates with a rise in the temperature of the gas 8, illustrated by the temperature curve 22. Since the boiling point 21 is reached at approximately second 60, the computing unit 26 transmits this information to the control unit 31, whereupon the power of the pump 6 is controlled 202 so that the total pressure 23 is kept constant once the boiling point 21 is reached, which can be clearly seen from the pressure curve 24 from second 60.The invention generally proposes a method 100 for detecting 105 a boiling point 21 of a liquid substance mixture 4 located in an evaporator flask 3 of a rotary evaporator 1, wherein a heating bath 10, into which the evaporator flask 3 is immersed, is heated 101, wherein a pump 6 generating a negative pressure is switched on 102, so that a gas 8 released from the liquid substance mixture 4 as a result of the heating 101 and / or the negative pressure flows 103 out of the evaporator flask 3, characterized in that a profile 20 of a flow parameter 11 of the flowing gas 8 is detected 104 and that the boiling point 21 of the liquid substance mixture 4 is detected 105 by automatically evaluating 106 the recorded 104 profile 20 of the flow parameter 11. Furthermore, a rotary evaporator 1, a measuring device 12 and a method 200 for controlling the rotary evaporator 1 are proposed. List of reference symbols 1 rotary evaporator 2 containers 3 evaporator flasks 4 liquid mixture 5 Sensor 6 Pump 7 Flow path 8 flowing gas 9 Flow sensor 10 Heating bath 11 Flow parameters 12 Measuring device 13 pipe section of 12 14 flange of 12 15 open ending of 13 16 interior of 13 17 electrical connecting cable of 12 18 Enclosure of 12 19 threads of 12 20 Course of the flow parameter 11 21 boiling point of 4 22 Temperature curve of 8 23 Total pressure 24 Pressure curve 26 computing unit 27 anemometers 28 Pressure sensor 29 Temperature sensor 30 heating element 31 control unit of 1 32 Flow line from 1 33 Capacitor 34 collecting flasks 35 control unit of 6 100 methods for detecting a boiling point 101 Heating of 10 102 Switching on 6 103 streams of 8 104 Recording a 20 of 8 105 Detection of a boiling point 21 106 automatic evaluation of the course 20 107 Recording of 22 108 Recording of 23 and / or 24 200 Methods for controlling a rotary evaporator 201 Triggering a control signal 202 Control of a system parameter of 1 p pressure t temperature U voltage

Claims

[1] Method (100) for detecting (105) a boiling point (21) of a liquid mixture (4) located in an evaporator flask (3) of a rotary evaporator (1), wherein a heating bath (10) into which the evaporator flask (3) is immersed is heated (101), wherein a pump (6) generating a negative pressure is switched on (102) so that a gas (8) released from the liquid mixture (4) as a result of the heating (101) and / or the negative pressure flows (103) out of the evaporator flask (3), characterized by that a profile (20) of a flow parameter (11) of the flowing gas (8) is recorded (104) and that the boiling point (21) of the liquid substance mixture (4) is detected (105) by automatically evaluating (106) the recorded (104) profile (20) of the flow parameter (11). [2] Method (100) according to claim 1, characterized bythat a detection (104) of the flow parameter (11) of the flowing gas (8) takes place at several, time-spaced, points in time, in particular two points in time, and / or continuously over time. [3] Method (100) according to one of the preceding claims, characterized by that a temperature profile (22) of the flowing gas (8) is recorded (107) and that the boiling point (21) of the liquid mixture (4) is detected (105) by automatically evaluating (106) the recorded (104) temperature profile (20). [4] Method (100) according to one of the preceding claims, characterized by that a total pressure (23) and / or a static pressure (24) is / are recorded (108), and / or that a dynamic pressure is determined, and that the boiling point (21) of the liquid substance mixture (4) is / are detected (105) by automatically evaluating the recorded total pressure (23) and / or the recorded static pressure (24) and / or the determined dynamic pressure. [5] Method according to one of the preceding claims, characterized by that the evaluation of the course (20) of the flow parameter comprises determining a value of a change in the detected flow parameter in a predetermined time period, and that the boiling point (21) is detected (105) by determining that a predetermined change value is exceeded. [6] Rotary evaporator (1), comprising a container (2) for a heating bath (10), an evaporator flask (3) rotatable in the container (2), a condenser (33), a collecting flask (34), a sensor (5) and a pump (6), wherein a flow path (7) of a gas (8) flowing out of the evaporator flask (3) can be formed by the pump (6) between the evaporator flask (3) and the pump (6), characterized by that the sensor (5) is a flow sensor (9) with which a flow parameter (11) of the gas (8) can be detected (104), and that the sensor (5) is arranged in the flow path (7). [7] Rotary evaporator (1) according to the preceding claim, characterized by that the rotary evaporator (1) is arranged to carry out the method (100) according to one of the preceding claims. [8] Rotary evaporator (1) according to one of the two preceding claims, characterized by that the rotary evaporator (1) has a flow line (32) connecting the condenser (33) and evaporator flask (3), in particular wherein the flow line (32) or a section of the flow line (32) is formed by a measuring device (12) as claimed herein. [9] Measuring device (12) for a rotary evaporator (1), comprising a flow sensor (9) with which a flow parameter (11) of a gas (8) can be detected (104), a pipe section (13) into which the flow sensor (9) is inserted, and two flanges (14a, 14b), each flange (14a, 14b) being formed at an open end (15) of the pipe section (13). [10] Measuring device (12) according to the preceding claim, characterized by in that the measuring device (12) comprises a computing unit (26) which is designed to automatically evaluate (106) a profile of the flow parameter (11) of the gas (8) detected (104) by means of the flow sensor (9). [11] Use of a flow sensor (9) for detecting (104) a flow parameter (11) of a gas (8) flowing in a rotary evaporator (1). [12] Use of a measuring device (12) according to one of claims 9 to 10 in a rotary evaporator (1). [13] Method (200) for controlling a rotary evaporator (1) according to one of claims 6 to 8, wherein a boiling point (21) of a liquid substance mixture (4) located in the evaporator flask (3) of the rotary evaporator (1) is detected (105) by means of a method (100) according to one of claims 1 to 5 and wherein a control signal is thereby triggered (201) with which a system parameter, in particular a total pressure (23), of the rotary evaporator (1) is regulated (202).

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