Method for monitoring a control parameter on a substantially plastic material, relating to apparatus and pyrolysis process which uses this method

A method for determining the value of at least one property “Px” of a substantially plastic material which includes the following steps:

• i) calculating, for each of said at least one property “Px”, a calibration curve “Cx” which, for sample materials having a known value of the property “Px”, correlates the spectrum in reflection with said property “Px”;
• ii) carrying out at least one measurement “Ax” of the reflection spectrum of said substantially plastic material;
• iii) determining the value of said at least one property “Px” of said substantially plastic material by means of a correlation of said at least one measurement “Ax” with said at least one calibration curve “Cx”;
• and which is characterised in that said substantially plastic material, in the spectrum measurement conditions in reflection, is in the molten state for at least 60% by weight, or between 70% and 99% by weight, or between 80% and 94% by weight of the material, with respect to the overall weight of the substantially plastic material, and by the fact that said at least one property “Px” of said substantially plastic material is the H/C index and/or the carbon index, wherein the carbon index and the hydrogen/carbon ratio (H/C index) are calculated according to the following formulas:
• H
• /
• C
• ⁢
• Index
• =
• 100
• ·
• 12
• 2
• ·
• Weight
• ⁢
• H
• ⁢
• atoms
• Weight
• ⁢
• C
• ⁢
• atoms
• ⁢
• Carbon
• ⁢
• Index
• =
• 100
• ·
• Weight
• ⁢
• C
• ⁢
• atoms
• Weight
• ⁢
• ALL
• ⁢
• atoms
• wherein said weights of the atoms are the weight of the atoms indicated in the substantially plastic material in its entirety.

An apparatus for determining the value of at least one property f a substantially plastic material at least in part in the molten state, wherein said at least one property “Px” of said substantially plastic material is the H/C index and/or the carbon index, wherein the carbon index and the hydrogen/carbon ratio (H/C index) are calculated according to the following formulas:

• H
• /
• C
• ⁢
• Index
• =
• 100
• ·
• 12
• 2
• ·
• Weight
• ⁢
• H
• ⁢
• atoms
• Weight
• ⁢
• C
• ⁢
• atoms
• ⁢
• Carbon
• ⁢
• Index
• =
• 100
• ·
• Weight
• ⁢
• C
• ⁢
• atoms
• Weight
• ⁢
• ALL
• ⁢
• atoms
• wherein said weights of the atoms are the weight of the atoms indicated in the substantially plastic material in its entirety, wherein said apparatus includes:
• 1) a cavity in which said substantially plastic material can slide, provided with an inlet and an outlet for said substantially plastic material at least in part in the molten state;
• 2) at least one probe capable of emitting light in said cavity;
• 3) at least one detection system optically coupled with said probe for detecting the reflected light and the determination of at least one analytical measurement “Ax”;
• 4) at least one sensor for reading the temperature connected to said cavity,
• 5) a system for determining said at least one property “Px” of said substantially plastic material at least in part in the molten state by correlating said at least one analytical measurement “Ax” with at least one calibration curve “Cx” obtained from sample materials having a known value of the “Px” property,
• wherein said cavity is able to withstand a pressure of at least 50 bara, or between 80 and 300 bara.