CALORIMETER

Abstract

The invention relates to improvements in the technical field of calorimetry. Hereby, in particular, a calorimeter (1) is proposed, that exhibits a pressure vessel (2) that is provided with a strain gauge (8). This is with the aim of coming to a conclusion on the deformation of a pressure vessel (2) when conducting calorimetric measurements at least indirectly on the internal pressure in the pressure vessel (2).

Claims

1. Calorimeter (1) for determining the calorific value of a sample (4), wherein the calorimeter (1) exhibits a pressure vessel (2) and a decomposition vessel (3) arranged in the pressure vessel (2) to take up a sample (4), wherein the calorimeter (1) includes at least one strain gauge (8) that is arranged relative to the pressure vessel (2) so as to determine a pressure-related deformation of the pressure vessel (2).

2.-12. (canceled)

13. The calorimeter (1) according to claim 1, wherein the calorimeter (1) includes a shutdown device (18a), that prevents the usage of the pressure vessel (2), with the at least one strain gauge (8) determining that a pressure limit has been exceeded.

14. The calorimeter (1) according to claim 1, wherein the at least one strain gauge (8) is arranged on an outer side (9) of the pressure vessel (2) facing away from the decomposition vessel (3).

15. The calorimeter (1) according to claim 1, wherein that the at least one strain gauge (8) is arranged directly on the pressure vessel (2).

16. The calorimeter (1) according to claim 1, wherein that the calorimeter (1) includes a measurement circuit (10) with which a temperature error of the at least one strain gauge (8) is able to be compensated for.

17. The calorimeter (1) according to claim 16, wherein that the measurement circuit (10) includes at least one second strain gauge (11), and wherein the at least one second strain gauge (11) is connected to the pressure vessel (2) in such a way that a heat transfer from the pressure vessel (2) to the at least one second strain gauge (11) occurs without the at least one second strain gauge (11) experiencing pressure-related stress and/or change of length.

18. The calorimeter (1) according to claim 16, wherein the measurement circuit (10) is set up to output a measured value that represents the pressure in the pressure vessel (2).

19. The calorimeter (1) according to claim 1, wherein the pressure vessel (2) is made of a good thermally conductive material.

20. The calorimeter (1) according to claim 1, wherein the calorimeter (1) includes at least one temperature sensor (14) arranged inside the pressure vessel (2).

21. The calorimeter (1) according to claim 1, wherein the calorimeter (1) includes a control unit (18) that suppresses an operation of the calorimeter (1) where there is an impermissible deformation of the pressure vessel (2) detected with the at least one strain gauge (8).

22. The calorimeter (1) according to claim 1, wherein the pressure vessel (2) includes an infeed (12) through which the pressure vessel (2) can be filled with liquid.

23. The calorimeter (1) according to claim 1, wherein the calorimeter (1) includes an information output device (19) through which information relating to a state of the pressure vessel (2), can be output.

24. The calorimeter (1) according to claim 1, wherein the calorimeter (1) includes a shutdown device (18a), that prevents usage of the pressure vessel (2), with the at least one strain gauge (8) determining that the pressure vessel (2) has been impermissibly deformed.

25. The calorimeter (1) according to claim 1, wherein the at least one strain gauge (8) is arranged on a bracket arranged on the pressure vessel (2).

26. The calorimeter (1) according to claim 17, wherein the at least one second strain gauge (11) is a temperature compensation strain guage.

27. The calorimeter (1) according to claim 19, wherein the good thermally conductive material is aluminum.

28. The calorimeter (1) according to claim 22, wherein the pressure vessel (2) includes an overrun (13) with a liquid sensor (13a).

29. The calorimeter (1) according to claim 22, wherein the infeed (13) includes a liquid sensor (12a).

30. The calorimeter (1) according to claim 23, wherein the information output device (19) includes a display.

31. The calorimeter (1) according to claim 23, wherein the information output device (19) is configured to output information relating to calorimetric measurements.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0037] Using the drawing, an illustrative example of the invention is described in more detail below. The single FIGURE shows highly diagrammatically a cross-sectional illustration of a calorimeter with a two-part pressure vessel and a decomposition vessel arranged therein, in which a sample may be combusted under an oxygen atmosphere.

DETAILED DESCRIPTION OF THE INVENTION

[0038] FIG. 1 shows a calorimeter designated as a whole with 1 for determining the calorific value of a sample 4. The calorimeter 1 exhibits a pressure vessel 2 and a decomposition vessel 3 arranged in the pressure vessel 2. The decomposition vessel 3 is used to take up the sample 4 to be combusted.

[0039] To combust the sample 4, the decomposition vessel 3 is filled with oxygen, which forms an oxygen atmosphere 6 in the decomposition vessel 3. This oxygen atmosphere 6 may exhibit an overpressure of, for example, 30 bar, compared with the ambient pressure. Then the sample 4 is ignited with the aid of the ignition device 5. The heat thus arising is passed onto a liquid via the decomposition vessel 3, that is to a water bath 7, inside the pressure vessel 2. Heating of the water bath 7 is measured and the calorific value of the probe 4 is determined from it.

[0040] The calorimeter 1 exhibits a strain gauge 8 that is arranged on the pressure vessel 2 and with which a pressure-related deformation of the pressure vessel 2 and therefore indirectly a pressure inside the pressure vessel 2 can be determined.

[0041] The FIGURE shows clearly that the strain gauge 8 is arranged on an outer side 9 of the pressure vessel 2. The outer side 9 of the pressure vessel 2 is therefore that side of the pressure vessel 2 that is facing away from the decomposition vessel 3 inside the pressure vessel 2. The strain gauge 8 is to be arranged directly on the outer side 9 of the pressure vessel 2 and in the present illustrative example also on a lower part 2a of the pressure vessel 2 in such a way that a pressure-related change of shape of the pressure vessel 2 can be transferred directly to the strain gauge 8. The lower part 2a of the pressure vessel 2 is connected via a flange 2b to the upper part 2c of the pressure vessel 2 such that it is pressure-tight.

[0042] On one underside of the lower part 2a of the pressure vessel 2, the strain gauge 8 is well protected and inside a housing 1a, indicated only highly diagrammatically, of the calorimeter 1.

[0043] The calorimeter 1 exhibits a measurement circuit 10 that is part of a pressure measurement system. With the aid of the measurement circuit 10, a temperature error of the strain gauge 8 used to determine a change of shape of the pressure vessel 2 and therefore to determine the pressure may be compensated for.

[0044] The measurement circuit 10 comprises the strain gauge 8 provided to determine the pressure and a second strain gauge 11 that may be used for a compensation of the temperature error and may therefore also be designated as temperature compensation strain gauge 11. The second strain gauge 11 is therefore connected to the pressure vessel 2 in such a way that a heat transfer from the pressure vessel 2 to this second strain gauge 11 occurs, without the second strain gauge 11 experiencing a pressure-related loading and/or change of length.

[0045] The measurement circuit 10 is set up to output a measured value representing the pressure in the pressure vessel 2. Both strain gauges 8 and 11 are identical strain gauges, so that the heat-related change of properties of the strain gauge 8 and a potentially therefore associated falsification of the pressure measurement determined by it can be particularly simply compensated for by the identically-reacting strain gauge 11 and its heat-related change considered in isolation.

[0046] To ensure a transfer of the temperature from the pressure vessel 2 to the second strain gauge 11, the pressure vessel 2 is manufactured from a good thermally-conducting material, e.g. of aluminium. The aim in the design of the pressure vessel 2 is that both strain gauges 8 and 11 in the measurement circuit 10 that must be arranged at different locations are heated in the same way. Hereby, it has proven to be advantageous if the pressure vessel 2 is made of good thermally-conducting material, e.g. of aluminium. Therefore, a homogeneous heating of both different locations at which both strain gauges 8 and 11 are arranged can be achieved. This may favour an accuracy of the temperature compensation in the determination of the deformation of the pressure vessel 2 and/or in the pressure determination of the pressure in the pressure vessel 2 by using the strain gauge 8.

[0047] Furthermore, the calorimeter 1 exhibits a temperature sensor 14 arranged inside the pressure vessel 2. With the aid of this temperature sensor 14, the heating of the water bath 7 inside the pressure vessel 2 when combusting the sample 4 may be measured and the calorimetric measurement conducted.

[0048] The measurement circuit 10 of the calorimeter 1 may be connected to a control unit 18 of the calorimeter 1 in such a way that the control unit 18 suppresses an operation of the calorimeter 1 when there is a plastic deformation of the pressure vessel 2 detected with the at least one strain gauge 8 and/or with the measurement circuit 10. For this purpose, the control unit 18 comprises a shutdown device 18a, that deactivates the calorimeter 1 with detected overload of the pressure vessel 2 and suppresses continued usage of the calorimeter 1 with the same pressure vessel 2.

[0049] The pressure vessel 2 of the calorimeter 1 exhibits an infeed 12. Through this infeed 12, the pressure vessel 2 is filled with liquid, here with the water bath 7. Through an overrun 13 that is provided on the end of the pressure vessel 2 opposite the infeed 12, the liquid the pressure vessel 2 is filled with when the pressure vessel 2 is filled completely seeps out again.

[0050] In the overrun 13, a liquid sensor 13a is arranged. In the infeed 12, a further liquid sensor 12a is provided. With the aid of both liquid sensors 12a and 13a, it may be established when filling of the pressure vessel 2 with liquid begins. As soon as the liquid sensor 12a arranged in the infeed 12 comes into contact with the liquid, it emits a corresponding signal. This may, for example, be processed by the control unit 18 already mentioned previously. The pressure vessel 2 continues to be filled with liquid. This is continued until the liquid sensor 13a arranged in the overrun 13 of the pressure vessel 2 comes into contact with the liquid and also emits a corresponding signal that can be processed by the control unit 18 of the calorimeter 1 accordingly. As soon as the second liquid sensor 13a in the overrun 13 of the pressure vessel 2 comes into contact with liquid, a proper and it can be concluded that the calorimeter 1 has been properly filled with liquid.

[0051] The calorimeter 1 also exhibits an information output device 19. This may be formed as an optical display device and/or as an audible signal device. Through this information output device 19, for example, a pressure value determined with the strain gauge 8 and/or with the measurement circuit 10, a temperature value and/or a proper filling of the pressure vessel 2 may be output to a user. The output of other information which may be of interest to the user of the calorimeter 1 is, of course, also possible.

[0052] Through an oxygen filling device 15, that is illustrated highly diagrammatically here only as an infeed and drain pipe, the decomposition vessel 3 may be filled with oxygen for producing the oxygen atmosphere 6. For example, this happens with a pressure of 30×10.sup.5 Pa. As soon as the pressure vessel 2 is completely filled with liquid, particularly with water, and the decomposition vessel 3 is filled with the oxygen atmosphere 6, the sample 4 is set on fire using the ignition device 5.

[0053] To distribute the heat dissipated from the sample 4 through the decomposition vessel 3 to the water bath 7 in the pressure vessel 2 into the water bath as uniformly and quickly as possible, and therefore distribute it inside the pressure vessel 2, the calorimeter 1 is equipped with a stirring device. This stirring device comprises a stirring drive 17 provided outside the pressure vessel 2. A stirring element 16 connected magnetically to the mixing drive 17 is arranged inside the pressure vessel 2 and, when the stirring device 17 is in operation, provides for a corresponding circulation of the water bath 7 and therefore for as homogeneous as possible a distribution of the heat inside the pressure vessel 2. Through the temperature sensor 14, the heat dissipated from the sample 4 when it is combusted and the associated increase in temperature of the water bath 7 can be determined and the calorimetric measurement is conducted.

[0054] With the aid of the measurement circuit 10 and both strain gauges 8 and 11 at least indirectly a corresponding pressure increase can be established, that indicates a proper ignition of the sample 4 inside the decomposition vessel 3. However, if a temperature increase in the water bath 7 that must be detected with the aid of the temperature sensor 14 does not happen, this may indicate that the stirring device 17 is not functioning properly or even that the magnetically-connected stirring element 16 has not been properly inserted inside the pressure vessel 2, therefore the circulation of the water bath 7 does not occur as provided.

[0055] With the aid of the strain gauge 8 or even with the aid of the measurement circuit 10, after releasing the atmosphere from the decomposition vessel 3 a pressure, that is greater than the ambient pressure, acting on the pressure vessel 2 is still detected, this also means a malfunction of the calorimeter 1. It is possible, in this case that, for example, the decomposition vessel 3 was not properly closed when it was filled with oxygen atmosphere 6 through the oxygen filling device 15 and possibly oxygen from the decomposition vessel 3 has got inside the pressure vessel 2. If the pressure in the pressure vessel 2 is too high, the calorimeter 1 emits, through its information output device 19, corresponding information to a user that the pressure vessel 2 must not or is not allowed to be opened due to the overpressure still present. Corresponding information may be output through the information output device 19 if, with the aid of the measuring circuit 10 and, in particular, the strain gauge 8, a plastic deformation of the pressure vessel 2 was able to be established. Then the pressure vessel 2 must be tested and replaced, as appropriate.

[0056] The invention relates to improvements in the technical field of calorimetry. Hereby, in particular a calorimeter 1 is proposed, that exhibits a pressure vessel 2 that is provided with at least one strain gauge 8. This is with the aim of measuring a deformation of the pressure vessel 2 when conducting calorimetric measurements and therefore conclude the internal pressure inside the pressure vessel 2 at least indirectly.