MEASURING CELL FOR CHEMICAL ANALYSES

Abstract

The present disclosure relates to a measuring cell for carrying out chemical analyses, having a vessel, in which at least one liquid to be analyzed is located; a heating wire, which is guided at least partially around an outer wall of the vessel, so that the liquid inside the vessel can be heated in a uniform and controlled manner; and a first temperature sensor, which determines and/or monitors a first temperature of the liquid. The measuring cell furthermore comprises a magnetic stirrer with a stir bar and a cover for closing the vessel, wherein the cover has a plurality of ducts, wherein at least one first duct is provided for at least one first analysis sensor, which determines and/or monitors at least one chemical and/or physical variable of the liquid of the vessel and wherein at least one second duct is provided for a liquid line.

Claims

1. A measuring cell for carrying out chemical analyses, having: a vessel, in which at least one liquid to be analyzed is located, a heating wire, which is guided at least partially around an outer wall of the vessel, so that the liquid inside the vessel can be heated in a uniform and controlled manner, a first temperature sensor, which determines and/or monitors a first temperature of the liquid, a cover for closing the vessel, wherein the cover has a plurality of ducts, wherein at least one first duct is provided for at least one first analysis sensor, which determines and/or monitors at least one chemical and/or physical variable of the liquid of the vessel, wherein at least one second duct is provided for a liquid line, and a magnetic stirrer with a stir bar, wherein the magnetic stirrer is arranged below the vessel and the stir bar is arranged inside the vessel.

2. The measuring cell of claim 1, wherein the heating wire is surrounded by an insulating jacket.

3. The measuring cell of claim 1, wherein the resistance of the heating wire increases with increasing temperature.

4. The measuring cell of claim 1, wherein the heating wire is fixed in position using an elastic molded jacket.

5. The measuring cell of claim 4, wherein the molded jacket of the heating wire is a shrink tube.

6. The measuring cell of claim of claim 4, wherein a thermal fuse is attached in the molded jacket of the heating wire.

7. The measuring cell according to claim 4, wherein a second temperature sensor for determining and/or monitoring a second temperature in the area of the heating wire is provided in the molded jacket of the heating wire, so that it is possible to establish if a maximum permissible value of the second temperature is exceeded.

8. The measuring cell of claim 1, wherein the heating wire is guided around the outer wall of the vessel as a compact package.

9. The measuring cell of claim 1, wherein the first temperature sensor regulates the heating of the vessel by the heating wire.

10. The measuring cell of claim 1, wherein the vessel and the heating wire are at least partially surrounded by a housing, which serves to thermally insulate the vessel and the heating wire.

11. The measuring cell of claim 10, wherein the cover and/or the magnetic stirrer can be connected to the housing.

12. The measuring cell of claim 1, wherein a blower is provided in the vicinity of the vessel and directs an air flow toward the vessel for cooling the vessel, and wherein the blower especially cools the region between the cover and an upper edge of the liquid of the vessel.

13. The measuring cell of claim 1, wherein the first temperature sensor is integrated into the first analysis sensor, or wherein a third duct for the first temperature sensor is provided in the cover.

14. The measuring cell of claim 13, wherein at least one fourth duct for venting the vessel is provided in the cover.

15. The measuring cell of claim 1, wherein a tube is attached to the at least fourth duct for venting the vessel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The measuring cell according to the present disclosure is explained in more detail below with reference to FIGS. 1-2. The following are shown:

[0029] FIG. 1 shows a schematic representation of a measuring cell according to the present disclosure.

[0030] FIG. 2 shows a schematic representation of the heating wire in detail.

DETAILED DESCRIPTION

[0031] The measuring cell 1 according to the present disclosure can be used for carrying out various chemical analyses, such as titration, digestion and/or pre-reaction before titration. In FIG. 1, the liquid 3 to be analyzed is placed in the vessel 2 and provided with a stir bar 11, which mixes the liquid by means of the magnetic stirrer 10 arranged below the vessel 2. There is no limitation with regard to the shape and size of the vessel 2; especially, small, standardized vessels can be used. The heating wire 4, which heats the liquid inside the vessel in a uniform and controlled manner, is at least partially guided around an outer wall of the vessel 2. By way of example, the heating wire is guided around the vessel between the bottom of the vessel and the upper edge of the liquid. The optional elastic molded jacket 13, which fixes the heating wire 4 in its position, is additionally shown. The heating wire 4 is shown in detail in FIG. 2. A thermal fuse 14 or a second temperature sensor 15 can additionally be arranged in the molded jacket; this determines and/or monitors a second temperature in the area of the heating wire 4 and by means of which it can be established if a maximum permissible value of the second temperature is exceeded.

[0032] The vessel 2 is closed by means of a cover 6, which closes the vessel 2 in an essentially gas-tight manner, so that no or only little liquid 3 in the form of vapor escapes from the vessel 2 during heating. A series of ducts 7a,b,c,d are introduced into the cover 6 and serve to accommodate further elements. A first analysis sensor 8, which determines and/or monitors at least one chemical and/or physical variable of the liquid 3 of the vessel 2, is accommodated in a first duct 7a. For example, the first analysis sensor 8 can be a pH, conductivity, redox electrode or a photometric transceiver system. A second duct 7b is provided for a liquid line 9. By means of the liquid line 9, liquid is added to the vessel 2, for example titrated, or removed from the vessel 2. A plurality of liquid lines for various liquids may also be used.

[0033] A first temperature sensor 5, which determines and/or monitors a first temperature of the liquid 3, is accommodated by way of example in a third duct 7c of the cover 6. Alternatively, the first temperature sensor can be integrated into the first analysis sensor 8, such as a redox electrode, which additionally determines and/or monitors the first temperature of the liquid 3. For example, the first temperature sensor 5 regulates the heating of the vessel 2 by the heating wire 4. Optionally, a fourth duct 7d is provided in the cover 6, which duct serves to vent the vessel 2 and to which duct a tube 18 is attached, for example.

[0034] For the thermal insulation of the vessel 2 and of the heating wire 4, a housing 16 can optionally at least partially surround the vessel 2 and the heating wire 4. The housing 16 can, for example, be connectable to the cover 6 and/or the magnetic stirrer 10, as indicated in FIG. 1 by the screws 19, so that a compact, stable measuring cell 1 is produced. With that said, other possibilities for connecting the housing 16 and the vessel 2 and/or the cover 6 are not ruled out. In order to rapidly cool the measuring cell 1 again after a heating process and prepare it for the next chemical analysis, a blower 17 is optionally arranged in the vicinity of the vessel 2. The blower 17 cools the vessel 2 by directing an air flow, which is indicated by arrows, toward the vessel 2. The blower 17 can also be used, for example, during a heating process, in order to cool the region between the cover 6 and an upper edge of the liquid 3 of the vessel 2 and thus promote condensation and recirculation of the evaporated liquid 3.

[0035] FIG. 2 shows the heating wire schematically in detail. By way of example, the heating wire 4 is wound around the outer wall of the vessel 2 as a compact package. By way of example, the heating wire 4 is surrounded by an insulating jacket 12 and a molded jacket 13. The molded jacket 13 can be, for example, a shrink tube. In order to avoid local temperature peaks at the heating wire 4, the heating wire 4 can be designed such that the resistance of the heating wire 4 increases with increasing temperature.