Method and device for the detection, characterization and/or elimination of suspended particles
Volatile suspended particles are eliminated from an aerosol by heating the aerosol to a temperature at which the volatile suspended particles evaporate and diluting the aerosol with a dilution gas. The sequence heating and diluting may be performed in any order. According to another aspect of the invention, dilution of the raw gas takes place such that raw gas is led to a measurement gas channel through which measurement gas flows, wherein the quantity of raw gas transferred per unit of time is dependent on the volume flow in the raw gas channel. According to a further aspect of the invention, in a condensation nucleus counter the number and intensity of scattered light pulses evaluated in order to be able to draw conclusions on the reliability of the measurement.
1. A device for characterising, separating and/or eliminating suspended particles in a carrier gas of an aerosol wherein the aerosol contains solid suspended particles and volatile suspended particles, comprising:
a gas supply and a gas discharge,
further comprising heating means for heating the aerosol to a temperature at which volatile suspended particles evaporate, but the solid suspended particles are unaffected,
a dilution unit for diluting the aerosol with a dilution gas, wherein, referring to a flow direction of the aerosol, the dilution unit is arranged upstream of the heating means, and
further comprising a measuring unit arranged downstream of the dilution unit and the heating unit, the measuring unit being capable of measuring either the characteristics of or the quantity of the unaffected solid suspended particles, or both, remaining in the aerosol downstream of the dilution unit and the heating unit.
2. A device for characterising, separating and/or eliminating suspended particles in a carrier gas of an aerosol wherein the aerosol contains solid suspended particles and volatile suspended particles, comprising:
a gas supply and a gas discharge,
further comprising heating means for heating the aerosol to a temperature at which volatile suspended particles evaporate, but the solid suspended particles are unaffected,
a dilution unit for diluting the aerosol with a dilution gas,
further comprising a measuring unit arranged downstream of the dilution unit and the heating unit, the measuring unit being capable of measuring either the characteristics of or the quantity of the unaffected solid suspended particles, or both, remaining in the aerosol downstream of the dilution unit and the heating unit, and
further comprising a saturator downstream of the heating means and of the dilution unit, in which the aerosol may be provided with a volatile substance and a condenser in which conditions prevail by way of which the volatile substance may be brought to supersaturation, a measurement volume in which the suspended particles from the condenser may be guided through a light beam, and detection means for detecting scatter light pulses that are caused by the scattering of light of the light beam on suspended particles, further comprising evaluation means that are designed for evaluating scatter light pulse intensities.
3. A method for detecting and characterising solid suspended particles in a carrier gas of an aerosol wherein the aerosol contains volatile suspended particles, comprising the steps of:
diluting the aerosol with a dilution gas thus forming a diluted mixture, and
heating the diluted mixture to a temperature at which volatile suspended particles evaporate, but the solid suspended particles are unaffected, thus forming a modified diluted mixture,
analyzing at least a representative portion of the modified diluted mixture to detect the presence of any solid suspended particles therein, and if present measuring either the characteristics of or the quantity, or both, of the unaffected solid suspended particles.