FR2783324A1 - Noack test apparatus for lubricating oil, has microprocessor controlled heating and timer - Google Patents

Abstract

The sample (7) is placed in a cylindrical metallic evaporation boat (1) in a heating chamber. The boat has a lid (2) connected to a vacuum source and with a temperature probe (4). Heating and heat transmitters (5, 6, 8) surround the boat and are controlled by a microprocessor in conjunction with a clock to ensure that the sample is heated to the correct temperature for the required time. An Independent claim is also included for the following: The method of performing a Noack test.

Description

The invention relates to the measurement of the volatility

  lity of liquid samples, more or less viscous and, in

  particular, petroleum products, especially lu- oils

  brittle. To carry out this measurement, specialists in the petrochemical field conventionally use the so-called "Noack" test which is defined by the CEC L-40A93 and ASTM D-5800 standards and which consists in determining the mass loss

  of a given quantity of the sample to be tested, heated during

  for one hour in a heating chamber brought to 250 ° C., under specific conditions of pressure

and suction.

  To carry out this test, a

  known apparatus in itself known as "volumetric meter

  Noack "which is described in the above standards.

  This device is schematically constituted by

  a heating enclosure (oven) comprising a recess of the

  ready to receive an evaporation crucible containing the sample to be tested; this evaporation crucible is hermetically closed by a cover connected to a vacuum pump and equipped with calibrated orifices for suction and passage of

  the air drawn in with a vacuum to be controlled.

  In its automated version, the heating enclosure

  fage is equipped with a temperature sensor cooperating with

  control members so as to regulate the temperature

  gaining in its internal part on the set point of 250 C

(for example).

  The evaporation crucible containing the sample to be tested must be introduced into the preheated oven; a clock indicates the end of the test (60 minutes after the crucible has been placed in the hot oven).

  It should be noted that during this measurement, the

  sample temperature is not controlled,

  only being controlled by the temperature prevailing in the part

dull from the oven.

  Therefore, to ensure that results are obtained

  reliable and reproducible, it is imperative to implement

  vre bodies ensuring excellent thermal contact between

  the heating block and the sample enclosed in the crucible.

  For this reason, in the classic Noack volatility measurement device, the recess receiving the evaporation crucible is filled with a particular alloy based on

  heavy metals: Wood's metal which guarantees in the li-

  that a supposed constant heat transmission between the heating block and the evaporation crucible plunging into

this alloy.

  This, whose melting point is 70 C, consists of 50% bismuth, 25% lead, 12.5%

  tin and 12.5% cadmium and therefore has a no-

  cif making it difficult to handle and inhaling dangerous-

  reuse. This harmfulness means that the use of Wood metal will soon be highly regulated or even totally

prohibited for some countries.

  In addition to this harmfulness, the use of Wood metal to ensure the transfer of heat in the device

  Noack's is linked to other disadvantages.

  It should, in particular, be noted that obtaining reliable measurements requires taking care to keep constant the level of the molten metal around the evaporation crucible, to prevent any oxidation of this metal and to clean the crucible

after each series of measurements.

  Another drawback related to the use of

  Tal de Wood is that it is necessary to pre-

  heat the oven to 250 C before first use (which requires about 1/2 hour), and put the crucible in the already hot molten alloy which corresponds to a delicate operation (risk of splashing ... ) to be carried out very quickly, in parallel with starting the vacuum pump and the clock, and closing

of the air intake circuit.

  In addition, given the fact that it is not pre-

  Since the temperature of the sample to be tested is directly measured, certain parameters can influence the reliability of the measurements made, such as for example the temperature

  ambient, barometric pressure, thermometer accuracy

  tre measuring the temperature of the heating block or variations in the air flow sucked which may occur following a

  fouling of the calibrated holes in the crucible cover.

  The object of the present invention is to remedy these drawbacks by proposing a device for heating and measuring the volatility of a liquid sample according to

  Noack's test (standards CEC L-40A93 and ASTM D-5800) avoiding having to resort to the use of Wood metal to carry out the heat transmission between the heating block10 and the sample test.

  To achieve this goal, we first sought to purely and simply replace the Wood alloy with a material other than such as to ensure sufficient thermal contact; however, it was not possible to

  discover a fully satisfactory material.

  Given this situation, we had the idea of trying to replace the prevailing temperature regulation

  within the heating enclosure, by a regulation

  correct the temperature of the sample for the purpose of

  ability to limit themselves to the use of a trans-

  thermal fert with characteristics inferior to that

Wood's metal.

  Now, we have seen that, in a surprising way

  nante, it is thus possible to reproduce the conditions of the Noack test, and in particular the temperature rise curve of the sample followed by a plateau at constant temperature, by only modifying the configuration to a very small extent of the device conventionally used for

implementation of this test.

  Consequently, the invention relates to a device

  heating and volatility measurement of a sample

  liquid tillon according to the Noack test, by determining the loss of mass of a given quantity of this sample heated for a determined period and under determined conditions, characterized in that it comprises: * a heating chamber containing a crucible cylindrical metallic evaporation closed by a cover connected to a vacuum pump and intended to receive the sample to be tested, * mechanical mechanical heating and transmission components

  heat, dry contact electrically controlled and

  turning the evaporation crucible, * a temperature probe passing through the cover of the evaporation crucible to plunge into the sample, * a clock, and

  * control elements containing a co-microprocessor

  operating with the temperature probe and with the heating and heat transmission devices to regulate the temperature of the sample as well as with the clock for

  connect or disconnect these devices.

  Such a device is in fact largely modeled on the Noack device, all the essential elements of which remain identical except for the addition of a temperature probe in the cover and the replacement of Wood's metal bath with organs. mechanical heating and

  dry contact heat transmission.

  According to the invention, these latter members are preferably constituted by a metal clamp, in particular brass, electrically heated, forming a sleeve for enveloping the side wall of the evaporation crucible and cooperating with a heating plate on which is placed. this

crucible.

  This heating plate can, for its part,

  taggingly be constituted by a disc in particular in

  brass pierced in its central part with a radial orifice

  slope receiving an electrically heated cylinder.

  According to another characteristic of the invention,

  the electrically heated cylinder consists of a re-

  resistance embedded in a ceramic and covered with a

stainless steel.

  It should be noted that in addition to replacing the bath

  of Wood metal by heating and transmitting

  dry contact heat, the implementation of the

  sitive according to the invention has multiple advantages; these are in particular linked, on the one hand, to an increase in the accuracy of the test following the measurement

  temperature of the sample and therefore to the limit

  tation of the influence of external parameters such as the

  bit of sucked air and, on the other hand, the removal of the obligation to rid the crucible of metal evaporation

  Wood after each try, as was previously necessary

  to be. The invention also relates to a method

  implemented when using the above device-

  born and allowing to reproduce perfectly a test of vola-

  Noack tility at the level of the test sample, in

  reproducing the temperature curve of this sample.

  Such a process could have been conceived thanks to the fact that, as was surprisingly observed, during the implementation of a Noack test, below a certain threshold, the first part of the rise temperature does not affect

  the result of the measurement and is therefore unimportant.

  The process according to the invention is, therefore, characterized in that: * in a preliminary step, a set temperature corresponding to the equilibrium temperature of a

  sample placed in the heating chamber of an appliance

  reil of Noack classic heated to a temperature of 250 C

(for example),

  e the sample to be tested is poured into the evaporation crucible, the crucible is closed with the cover, it is placed in the heating chamber of the heating and volatility measurement device,

  * the heating and vacuum and trans-

  heat mission so as to control the rise in temperature of the sample to be tested and then it is regulated to the set value, * when the temperature of the sample reaches a value

  located 5 C below the set temperature,

  operates the clock for a period of 55 minutes, and when these 55 minutes have elapsed, the heating and heat transmission devices are disconnected, the crucible containing the sample is extracted from the heating chamber and determines the loss of mass of it

after cooling.

  It is clear that during the implementation of this process, the positioning of the evaporation crucible contains

  mant the sample to be tested is significantly simplified; indeed, the device is operational as soon as it is switched on and therefore this positioning can be carried out cold and without precipitation; in addition, the temperature of the sample at the end of the test can be displayed, which makes it possible to avoid burns and the heating of the oven is

  in addition, stopped after each test.

  According to the invention, it has been observed that the temperature

  set point for a standard test at 2500C is located

  between 244 C and 247 C with a stability of 0.5 C.

  It was also observed that the rise in temperature

  sample temperature between 100 ° C and the set temperature

  gne -5 C requires 5 minutes and this rise in temperature

  must be completed after 10 minutes.

  Consequently and according to another characteristic of the invention making it possible to facilitate the work of the operator, for a conventional test of 60 minutes, when

  the sample temperature reaches 100 C, the clock

  shows the remaining time of 55 minutes (automatic countdown-

  ment) when the set temperature minus 5 C is

reached.

  According to a particularly advantageous characteristic

  tagger of the invention, the implementation of the method is com-

automatically mandated.

  The characteristics of the device as well as of the method which are the subject of the invention will be described in more detail with reference to the accompanying drawings, in which: - Figure 1 is a schematic section of the crucible

  of evaporation surrounded by heating and trans-

  heat mission, - Figure 2 is a template of the temperature of

the sample being tested.

  According to FIG. 1, the sample to be tested E is placed in a cylindrical metallic evaporation crucible 1 closed by a cover 2 equipped with a suction tube 3 connected to a vacuum pump as well as a temperature probe - ture 4 immersing in the sample E at a distance from the bottom H of 10 mm in the center of the crucible. 5 The evaporation crucible 1 is mounted on the internal part of a heating enclosure, not shown, where it is placed on a brass heating plate 5 in the form of a disc pierced in its central part with a through radial orifice receiving an electrically heated cylinder 6. The cylinder 6, which is shown diagrammatically in the figure, is constituted by a resistor embedded in a ceramic and bearing a stainless steel coating. The side wall 7 of the evaporation crucible 1 is, moreover, surrounded by a brass clamp 8

forming a sleeve.

  According to Figure 2, the temperature of the sample must meet the following conditions: Setpoint temperatures -10 C reached in 5 minutes

  maximum (from the moment the sample has

  complexion 100 C), Setpoint temperatures 0.5 C reached at the latest in minutes, The regulation must then maintain the sample at

setpoint temperature 0.5 C.

Claims (7)

R E V E N D I C A T IONS   1) Heating and volatility measurement device   a petroleum product, in particular a lubricating oil   lon the Noack test (CEC L-40A93 and ASTM D-5800 standards) by which the mass loss of a given quantity of the heated sample is determined for a determined period and under determined conditions, characterized in that '' it includes: e a heating enclosure containing a crucible   cylindrical metallic evaporation (1) closed by a cover   ring (2) connected to a vacuum pump and intended to receive the sample to be tested, * mechanical heating and heat transmission elements (5, 6, 8) with electrically controlled dry contact and surrounding the crucible evaporation (1),   * a temperature probe (4) passing through the cover   key (2) of the evaporation crucible (1) to immerse in the sample, up to a height (H) relative to the bottom of the crucible, * a clock, and   * control elements automatically controlled, for example   ple by a microprocessor cooperating with the time probe   temperature (4) and with the heating and   heat transmission (5, 6, 8) to regulate the temperature   deletion of the sample as well as with the clock for expensive or disconnect these organs.   2) Device according to claim 1, characterized in that the heating and heat transmission members are constituted by a metal clamp (8)   electrically heated forming a sleeve to wrap the pa-   lateral king (7) of the evaporating crucible (1) and cooperating   with a heating plate (5) on which this hollow is placed set (1).   3) Device according to claim 2, characterized in that   the heated metal clamp (8) is made of brass.   4) Device according to any one of claims 2 and 3, characterized in that   the heating plate (5) is constituted by a disc in particular   made of brass which is pierced in its central part with an ori-   radial through hole receiving a heated cylinder (6) l0 electrically.    ) Device according to. claim 4, characterized in that the electrically heated cylinder (6) consists of a resistor embedded in a ceramic and carrying a coating Stainless steel.   6) Process implemented when using the device   according to any one of claims 1 to 5,   characterized in that * in a preliminary step, a set temperature corresponding to the equilibrium temperature of a   sample placed in the heating chamber of an appliance   reil of classic Noack heated to a given temperature, for example 250 C, * the sample to be tested is poured into the evaporation crucible, this crucible is closed with the cover and it is placed in the heating chamber of the device and heating and volatility measurement,   e connect the vacuum and heating and trans-   heat mission so as to control the rise in   temperature of the sample to be tested and then to regulate it   ci on the set value, * when the sample temperature reaches a value   located 5 C below the set temperature,   operates the clock for a period of 55 minutes, and * when these 55 minutes have elapsed, the heating and heat transmission members are disconnected, the crucible containing the sample of the heating chamber is extracted and O10 we determine the mass loss of it after cooling.   7) Method according to claim 6, characterized in that the set temperature is located (for a classic Noack test at 250 C) between 244 C and 247 C and must be regulated at 0.5 C.   8) Method according to any one of claims 6 and 7, characterized in that   its implementation is controlled automatically, for example by a microprocessor. 15