Devices, methods, and systems for detecting particles in aerosol gas streams

Abstract

Turbulent mixing condensation devices, methods, and systems adapted to condense a working fluid on particles from a sample gas to enlarge the particles for subsequent detection are provided. The device includes a vapor generator adapted to produce a working-fluid saturated carrier gas and a condensation chamber. The working-fluid saturated carrier gas is mixed with a sample gas containing particles to be detected and is then introduced to the condensation chamber. The operating conditions are controlled to enhance the condensation of the working fluid on the particles. The particles are typically forwarded to a particle detection device to detect at least one characteristic, for example, the size, of the particles. The flow of carrier gas to the vapor generator may be regulated to vary the degree of saturation of the carrier gas with working fluid.

1 . A method for detecting a characteristic of particles of varying size in a sample gas, the method comprising:
 introducing a working fluid to a carrier gas to provide a first mixture of working fluid and carrier gas having a first saturation ratio;   introducing the sample gas to the first mixture, the sample gas containing particles, to produce a first particle-containing gas;   condensing at least some of the working fluid from the first particle-containing gas onto at least some of the particles in the sample gas stream having a first size to produce first enlarged particles;   detecting the characteristic of at least some of the first enlarged particles;   introducing the working fluid to the carrier gas to provide a second mixture of working fluid and carrier gas having a second saturation ratio, different from the first saturation ratio;   introducing the sample gas to the second mixture to produce a second particle-containing gas;   condensing at least some of the working fluid from the second particle-containing gas onto at least some of the particles in the sample gas stream having a second size, different from the first size, to produce second enlarged particles; and   detecting the characteristic of at least some of the second enlarged particles.   
     
     
         2 . The method as recited in  claim 1 , wherein introducing the working fluid to the carrier gas comprises passing a first stream of carrier gas over a supply of working fluid to produce a first mixture of working fluid and carrier gas and mixing the first mixture with a second stream of carrier gas. 
     
     
         3 . The method as recited in  claim 2 , wherein the method further comprises controlling the flow of the first stream of carrier gas and the second stream of carrier gas to produce the first saturation ratio. 
     
     
         4 . The method as recited in  claim 1 , wherein the method further comprises, prior to introducing the working fluid to the carrier gas, drying the carrier gas to remove at least some moisture from the carrier gas. 
     
     
         5 . The method as recited in  claim 4 , wherein drying comprising removing at least 80% of the moisture from the carrier gas. 
     
     
         6 . The method as recited in  claim 1 , wherein introducing the working fluid to the carrier gas comprises passing the carrier gas over the working fluid. 
     
     
         7 . The method as recited in  claim 1 , wherein introducing the working fluid to the carrier gas comprises injecting the working fluid into the carrier gas. 
     
     
         8 . A method for detecting a characteristic of particles in a sample gas, the method comprising:
 dehumidifying a carrier gas to remove at least some moisture from the carrier gas;   introducing the dehumidified carrier gas to a working fluid to provide a mixture of carrier gas and working fluid;   introducing the sample gas containing particles to the mixture to produce a particle-containing gas;   condensing at least some of the working fluid onto at least some of the particles to produce enlarged particles; and   detecting the characteristic of at least some of the enlarged particles.   
     
     
         9 . The method as recited in  claim 8 , wherein the enlarged particles contain less condensed water than particles produced by a method without dehumidifying the carrier gas. 
     
     
         10 . The method as recited in  claim 8 , wherein dehumidifying the carrier gas removes at least 50% of the moisture from the carrier gas. 
     
     
         11 . The method as recited in  claim 10 , wherein dehumidifying the carrier gas removes at least 90% of the moisture from the carrier gas. 
     
     
         12 . The method as recited in  claim 8 , wherein introducing the dehumidified carrier gas to a working fluid comprises passing the carrier gas over the working fluid. 
     
     
         13 . The method as recited in  claim 8 , wherein introducing the dehumidified carrier gas to a working fluid comprises injecting the working fluid into the carrier gas. 
     
     
         14 . A method for detecting a characteristic of particles in a sample gas, the method comprising:
 introducing a carrier gas to a working fluid to provide a mixture of carrier gas and working fluid;   introducing the sample gas containing particles to the mixture to produce a particle-containing gas;   condensing at least some of the working fluid on to at least some of the particles in the particle-containing gas to produce enlarged particles;   detecting the characteristic of at least some of the enlarged particles; and   recovering at least some of the working fluid from particle-containing gas.   
     
     
         15 . The method as recited in  claim 14 , wherein recovering at least some of the working fluid from the particle-containing gas comprises recovering at least some of the working fluid from at least one of the gas in the particle-containing gas and the enlarged particles in the particle-containing gas. 
     
     
         16 . The method as recited in  claim 15 , wherein recovering at least some of the working fluid from the particle-containing gas comprises recovering at least some of the working fluid from the gas by passing the gas in heat exchange relationship with a cooler fluid. 
     
     
         17 . The method as recited in  claim 14 , wherein the method further comprises re-using the recovered working fluid as a source of working fluid. 
     
     
         18 . The method as recited in  claim 14 , wherein the method further comprises filtering the recovered working fluid to remove at least some particles from the recovered working fluid. 
     
     
         19 . The method as recited in  claim 14 , wherein introducing the dehumidified carrier gas to a working fluid comprises passing the carrier gas over the working fluid. 
     
     
         20 . The method as recited in  claim 14 , wherein introducing the dehumidified carrier gas to a working fluid comprises injecting the working fluid into the carrier gas.