TEMPERATURE-CONTROL DEVICE AND METHOD FOR A FLASH-POINT DETERMINATION TEST AND/OR FIRE-POINT DETERMINATION TEST

Abstract

A device for tempering a sample located in a container for a flash point determination test and/or fire point determination test is provided, the device comprising: a temperature control block having a, in particular cylindrical, container receptacle for receiving the container; a cooling air guide body for delimiting a cooling air path in which the temperature control block is arranged; wherein the temperature control block has an outer surface with fins.

Claims

1-21. (canceled)

22. A device for tempering a sample located in a container for a flash point determination test and/or fire point determination test, the device comprising: a temperature control block having a container receptacle for receiving the container; a cooling air guide body for delimiting a cooling air path in which the temperature control block is arranged; wherein the temperature control block has an outer surface with fins.

23. The device according to claim 22, wherein a cooling channel is formed between each two adjacent fins, within which cooling air flows substantially parallel to the fins; and/or wherein the temperature control block has a wall thickness at positions of fins which is greater than the wall thickness at positions between the fins.

24. The device according to claim 22, wherein the cooling air guided in the cooling air guide body has a substantially horizontally extending flow direction in the region of the temperature control block.

25. The device according to claim 22, wherein the outer surface of the temperature control block comprises a shell surface and a lower outer surface, wherein the shell surface and/or the lower outer surface are exposed to the cooling air within the cooling air guide body.

26. The device according to claim 25, wherein first fins are each formed in a circular circumferential manner and form parts of the shell surface of the temperature control block.

27. The device according to claim 26, wherein the first fins extend parallel to one another in different horizontal planes vertically spaced apart from one another.

28. The device according to claim 26, wherein a first cooling channel is formed between each two adjacent first fins, within which cooling air flows in the circumferential direction of the temperature control block in a clockwise direction in one part of the cooling channel and in an anticlockwise direction in another opposite part of the cooling channel.

29. The device according to claim 26, wherein second fins are provided at the lower outer surface of the temperature control block.

30. The device according to claim 29, wherein the second fins extend parallel to one another in a horizontal plane and are laterally spaced apart from one another in a horizontal direction perpendicular to the flow direction of the cooling air, wherein a second cooling channel is formed between each two adjacent second fins, within which cooling air flows.

31. The device according to claim 22, wherein at least one thermal protection element is arranged within the cooling air guide body upstream of the temperature control block, said thermal protection element absorbing parts of a thermal radiation originating from the temperature control block and/or reducing a convection of air from the temperature control block to another component.

32. The device according to claim 31, wherein the thermal protection element comprises at least one pivotable thermal protection flap, wherein the thermal protection flap in the open state substantially clears the cooling air path and in the closed state at least partially blocks the cooling air path.

33. The device according to claim 31, wherein the at least one thermal protection flap transitions from the closed state to the open state by pivoting due to a flow of cooling air during a cooling operation.

34. The device according to claim 22, wherein a cross-sectional size of the cooling air path decreases in the region of the temperature control block from upstream to downstream.

35. The device according to claim 22, wherein the cooling air guide body has an inlet opening for admitting cooling air from outside the device, wherein the device further comprises a fan upstream of the temperature control block and/or the thermal protection element, which is configured to convey the cooling air admitted via the inlet opening from outside to inside of the cooling air guide body towards the temperature control block.

36. The device according to claim 35, wherein the cooling air guide body is formed, such that the cooling air flows to the temperature control block on an upstream side with an inflow direction, flows laterally around and/or below the temperature control block and leaves the temperature control block at a downstream side opposite the upstream side with an outflow direction, wherein the outflow direction is substantially equal to the inflow direction.

37. The device according to claim 22, further comprising: a temperature sensor which is configured to measure the temperature of the temperature control block.

38. The device according to claim 22, wherein the temperature control block comprises an electric heating wire for heating the temperature control block.

39. The device according to claim 37, further comprising: a controller which is configured to control a fan and/or a heating wire depending on the measured temperature of the temperature control block.

40. A flash point determination apparatus comprising: a container for receiving a sample to be examined; a device for tempering the sample located in the container according to claim 22, wherein the container is insertable into the container receptacle of the temperature control block; and an ignition device for igniting the sample.

41. A method of tempering a sample located in a container for a flash point determination test and/or a fire point determination test, the method comprising: receiving the container in a container receptacle of a temperature control block; cooling an outer surface of the temperature control block having fins within a cooling air path delimited by a cooling air guide body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] FIG. 1 illustrates, in a schematic sectional view, a flash point determination apparatus, in particular also designed for fire point determination, according to an embodiment of the present invention;

[0061] FIG. 2 illustrates, in a schematic perspective sectional view, a device for tempering a sample located in a container according to an embodiment of the present invention;

[0062] FIGS. 3A, 3B, and 3C illustrate, in a sectional view, a perspective view, and a cross-sectional perspective view, respectively, a temperature control block as it may be provided in a device for tempering a sample according to an embodiment of the present invention; and

[0063] FIG. 4 illustrates, in a schematic sectional illustration with a viewing direction along the vertical direction, a cooling air flow as it may be generated in embodiments of the present invention.

DETAILED DESCRIPTION OF AN EMBODIMENT

[0064] According to an embodiment of the present invention, the flash point determination apparatus 1 shown in FIG. 1 in a sectional view, which is in particular also designed for fire point determination, comprises a container 3 for receiving a sample 5 to be examined, which is in a liquid state. Furthermore, the flash point determination apparatus 1 comprises a device 7 for tempering the sample 5 locared in the container according to an embodiment of the present invention, which is also illustrated in a perspective sectional view in FIG. 2. The flash point determination apparatus 1 further comprises an ignition device not shown, which is provided for igniting the sample 5 within the container 3, a stirring device 10 with stirrer 12, and a flash point and temperature detector 14 with temperature sensor 16, which extends into the liquid part of the sample 5.

[0065] According to an embodiment of the present invention, the device 7 for tempering the sample 5 located in the container 3 for a flash point determination test and/or a fire point determination test comprises a temperature control block 11 as also illustrated in FIGS. 3A, 3B, 3C, with a, in particular cylindrical, container receptacle 13 for receiving the container 3. The device 7 further comprises a cooling air guide body 15 for delimiting a cooling air path 8 in which the temperature control block 11 is arranged for air cooling.

[0066] In this regard, the temperature control block 11 has an outer surface with fins 17, 18. As seen in the sectional view in FIG. 3A along a horizontal direction 19, a cooling channel 23 is formed between each two adjacent first fins 17, within which cooling air flows substantially parallel to the fins 17. As can also be seen from FIG. 3A, the temperature control block 11 has a wall thickness d1 at positions of the first fins 17 which is greater than the wall thickness d2 at positions between the first fins 17. The depth of the channels or height (radial extent) of the fins 17 may be, for example, between 5 mm and 30 mm. The (vertical) distance between two of the fins 17 may be, for example, between 2 mm and 15 mm.

[0067] The device 7, and in particular the cooling air guide body 15, further comprises an inlet opening 25 for admitting cooling air 34 from outside the device, and the device 7 further comprises a fan 27, in particular a radial fan, upstream of the temperature control block 11, which is configured to convey the cooling air 34 admitted via the inlet opening 25 from the outside to the inside of the cooling air guide body, i.e. into the cooling air path 8, towards the temperature control block 11. For this purpose, the radial fan has blades 29 projecting radially outwards. By means of an electric motor not shown, the fan 27 is set in rotation (about a horizontal axis of rotation 26), at least when a cooling operation is desired, in order to convey cooling air 34 along a flow direction, in particular an inflow direction 35, towards the temperature control block 11.

[0068] In particular, the cooling air 34 flows to the temperature control block 11 at an upstream side 37 with the inflow direction 35, flows around the temperature control block 11 laterally and below and leaves the temperature control block 11 at a downstream side 39 opposite the upstream side 37 with an outflow direction 41 which is substantially equal to the inflow direction 35. The vertical direction is designated by reference number 21 and two horizontal directions are designated by reference numbers 19 and 22. Both the inflow direction 35 and the outflow direction 41 are substantially aligned along the horizontal direction 22. Thus, the cooling air of the temperature control block 11 is guided substantially in a horizontally extending flow direction.

[0069] The temperature control block 11 has a substantially cylindrical symmetry, with the axis of symmetry 43 shown in FIG. 3A and FIG. 3C. The first fins 17 and the cooling channels 23, which are formed on a shell surface 45 in a side wall 46 of the temperature control block 11, also obey the cylindrical symmetry. Not only the shell surface 45, but also a lower outer surface 47 of the temperature control block 11 are exposed to the cooling air 34 within the cooling air guide body 15. The first fins 17 are each formed in a circular circumference around the temperature control block, and form parts of the shell surface 45 of the temperature control block 11.

[0070] As can be seen, for example, from FIGS. 3A, 3B, 3C, the first fins 17 extend parallel to each other in different horizontal planes vertically spaced apart from each other. A first circular cooling channel 23 is formed between each two adjacent first fins 17, within which cooling air 34 flows in the circumferential direction 49 or 51 of the temperature control block 11 in a clockwise direction 51 in one part of the cooling channel and in a counterclockwise direction 49 in another opposite part of the cooling channel.

[0071] At the lower surface 47, the temperature control block 11 comprises second fins 18. The second fins 18 extend parallel to each other in a (single) horizontal plane along the horizontal direction 22 and are laterally spaced apart from each other in a horizontal direction 19 perpendicular to the flow direction 35, 41 of the cooling air 34. A second, in particular rectilinear, cooling channel 20 is formed between each two adjacent second fins 18, within which the cooling air 34 flows.

[0072] As illustrated in FIGS. 1 and 2, at least one thermal protection element 53 is arranged within the cooling air guide body 15 upstream of the temperature control block 11, which absorbs parts or portions of a thermal radiation 55 originating from the temperature control block 11 and/or reduces a convection of air from the temperature control block 11 to another component arranged upstream. In the illustrated embodiment, the thermal protection element 53 is formed by two pivotable thermal protection flaps 57, wherein the thermal protection flaps 57, in the open state, in particular in a vertical position, substantially clears the cooling air path and, in the closed state, at least partially blocks the air path. The thermal protection flaps are pivotable about horizontally extending axes of rotation 59 and may transition from the closed state (vertical position) 57 illustrated in FIG. 1 to an open state 57′ shown in dashed lines, wherein the flaps may be brought into an almost horizontal orientation. The thermal protection flaps 57 may transition from the closed state 57 to the open state 57′ solely by the flow of cooling air 34 during operation of the fan 27.

[0073] The temperature control device 7 illustrated in FIGS. 1 and 2 with the temperature control block 11 illustrated in FIGS. 3A, 3B, 3C is primarily suitable for use in flash point testers employing the Pensky-Martens and/or Cleveland analysis methods as their primary application. Essential components of the temperature control device 7 are the finned heating block 11, which is positioned in a cooling air path 8. The heating block (also referred to as the temperature control block) may be made of, for example, a metallic high temperature resistant metal alloy.

[0074] The temperature control block further comprises an electric heating wire 61 for heating the temperature control block, which is arranged in particular inside a lower end wall 48 of the bottom side 47 of the temperature control block 11, in particular circumferentially in the circumferential direction. The heating wire 61 further comprises electrical supply lines 63 connected to a suitable power supply and controlled in particular by a controller 70 (see FIG. 1).

[0075] Furthermore, the temperature control block 11 comprises a temperature sensor 65 which is configured to measure the temperature of the temperature control block 11 and which is arranged in particular centrally at a lower end wall 48 of the temperature control block 11. Measuring signals 71 of the temperature sensor 65 are supplied to a controller 70 via electrical conduits 67.

[0076] FIG. 1 further illustrates the controller 70, which is configured to control the fan 27 via supply line 74 and/or the heating wire 61 via supply lines 63 in response to a temperature signal 71 generated by the temperature sensor 65 via corresponding control signals 73 and 75, respectively. In this way, a desired temperature control of the temperature control block 11 and thus also of the sample within the container 3 may be achieved.

[0077] As can be seen, for example, from FIG. 1, an upper edge 77 of the temperature control block 11 is also located within the cooling air path 8, so that this upper edge 77 and a small portion of the side wall of the container 3 may also be cooled by the cooling air 34. In particular, spacers 79 are provided so that a gap is formed between the upper mounting edge of the cooling air path 8 and the upper edge or top termination 77 of the temperature control block. This gap located in the cooling air path 8 may provide for an optimized cooling of the crucible 3 filled with the sample 5, which is inserted into the temperature control block 11 during a flash point determination measurement, as also illustrated in FIG. 1.

[0078] At a downstream side 81, the cooling air guide body 15 is open to discharge exhaust air to the surroundings. In the area of the downstream side, there are ventilation gills 42 which draw cooling air into the ventilation path 41 and mix it with the hot air. The fan 27 or ventilator 27 is installed at the front end of the cooling air path 8 in a heat-decoupled manner. Since the temperature control block becomes hot or may be heated up to 650° C. and the fan 27, which among other things consists of plastic parts, could be damaged, the two metallic thermal protection flaps 57 are installed upstream of the temperature control block 11, The flaps 57 are oriented vertically (position 57) during the heating phases, so that the radial fan 27, which is offset downwardly relative to the heating block, is exposed to minimal heat radiation. During the cooling process after flash point determination, the flaps are positioned substantially horizontally by the air movement to reach the position 57′ so that an unobstructed cooling air flow and thus an optimal cooling of the temperature control block 11 together with the sample container 3 is possible. Moreover, the cooling air path 8 is externally covered with an insulating material in the region of the temperature control block position, so that the heating processes for the flash point determination may be optimally controlled.

[0079] In FIG. 4, the cooling air path 8 within the cooling air guide body 15 is illustrated in a sectional illustration viewed along the vertical direction 21 by an arrow illustration, wherein the direction of the arrows 36 indicates the flow direction and the length of the arrows 36 indicates the flow velocity of the cooling air 34. The cooling air path 8 is delimited by the cooling air guide body 15, and the heating block 11 is arranged within the cooling air path 8.

[0080] At the upstream side 37, the cooling air path 8 has a cross-sectional size Q1, while at the downstream side 39, the cooling air path 8 has a cross-sectional size Q2 that is smaller than the cross-sectional size Q1. As a result, the flow velocity in the region of the downstream side 39 is higher than in the region of the upstream side 37. In particular, the cross-sectional size may decrease (continuously or gradually) from the upstream side 37 towards the downstream side 39 in order to result in a continuously or gradually increasing flow velocity.

[0081] The following features of the temperature control device promote the cooling process:

[0082] 1) Circumferential first fins 17 located on the shell surface 45 of the temperature control block 11 provide good heat transfer from the temperature control block 11 to the cooling air 34. At positions of greatest thickness, they comply with the standard and substantially reduce the cooling mass of the temperature control block at positions of least thickness.

[0083] 2) The fins 17, 18 are aligned along the air flow 35, 41, whereby cooling air 34 flows well around the heating block 11 and as little as possible of the flow is guided over edges transverse to the flow direction. As a result, as few poorly cooling flow separations of the cooling air as possible are formed.

[0084] 3) In comparison with a heating block without fins, the surface area is multiplied with the fins 17, 18, whereby the heat transfer to the cooling air 34 is increased by approximately the same factor. The circumferential fins 17 of the heating block 11, except for the areas of inflow and outflow, are enclosed by a cylindrical sheet metal part, whereby cooling channels 23 in the form of ring segments are formed on both sides, as also illustrated in FIG. 4. As illustrated in this FIG. 4, the cooling air is directed along a certain path around the heating block by means of these cooling channels and the dead water area is reduced.

[0085] 4) Due to the cooling, the temperature of the air increases from the upstream or inflow 37 to the downstream or outflow 39, As a result, the temperature gradient to the wall of the heating block is higher on the upstream side than on the downstream side and thus the upstream side of the heating block is cooled better. To reduce this effect, the heating block and cylinder segment of the air channel may be positioned eccentrically so that the annular segment has a higher cross-section Q1 at the upstream side 37 than at the downstream side 39. This increases the flow velocity as the air flows around the heating block 11 and provides better cooling at the downstream side 39 due to the higher flow velocity. The increase in flow velocity is accompanied by pressure loss, therefore a fan should be selected which may offer corresponding pressure ratios (e.g., radial fan).

[0086] 5) At the bottom side 47 of the heating block there are also fins 18, which are arranged in the flow direction. These additionally support the cooling of the heating block 11 and ensure the cooling of the heating cartridges or the heating wire 61, so as not to delay the cooling process with their residual heat.

[0087] Advantages of embodiments of the present invention include a significant mass reduction of the temperature control block due to the provision of the fins, which are formed by varying wall thickness, Due to a reduced temperature control block wall thickness, a reduction in the mass of the temperature control block is achieved, resulting in a higher heating rate and also cooling rate. This results in an efficient and innovative heating/cooling concept conforming to standards for flash point testers and also fire point testers. An improved heating rate during the temperature-controlled processes may be achieved by avoiding air exchange of the heating chamber with the environment by free convection and by minimizing the thermal mass to be heated.

[0088] Furthermore, high heating and cooling rates are achieved by the design adaptation of the temperature control block (mass reduction, design of the cooling fins, suitable choice of fan and targeted air guidance), High cooling rates are also achieved by using a radial fan for high air flow per time unit. High cooling rates of the sample container are achieved by recessed mounting of the temperature control block in the cooling air path. The gap of approx. 4.5 mm between the crucible support and the upper edge of the heating block required by the standard is thus in the cooling air flow and additionally supports cooling.

[0089] Improved cooling rates and reduction of residual heat of the heating cartridges during the cooling process are achieved. The heating cartridges positioned parallel to the air flow are efficiently cooled by lower cooling fins of the block.

[0090] Possible use of commercially available fans made of plastic, despite heating block temperatures of around 650° C., are made possible by a directed offset of the fan downwards relative to the heating block and by fitting protective flaps. The protective flaps are self-opening during the cooling process and do not interfere with the efficiency of the cooling.