Particulate matter generator and collector

Abstract

An apparatus for generating and collecting particulate matter derived from combusting a carbon-containing fuel in oxidising gas comprises a fuel burner with a nozzle housed in a container. The container has a gas inlet and a gas outlet; the gas outlet connects with a conduit for transporting the gas to atmosphere which is associated with means for forcing gas to flow from the gas inlet via the container and the conduit to atmosphere. Located within the conduit is a station for collecting particulate matter from gas flowing through the conduit. The gas flow-forcing means is controlled in response to a detected gas flow rate at the gas inlet to ensure the rate of gas flow at the gas inlet is maintained at a desired rate, thereby to promote particulate matter formation. A method for collecting particulate matter derived from combusting carbon-containing fuel is also disclosed.

What is claimed: 
     
         1 . An apparatus for generating and collecting particulate matter derived from combusting a liquid carbon-containing fuel, which apparatus comprising a fuel burner comprising a nozzle, which nozzle is housed in a container, which container comprising a gas inlet and a gas outlet, said gas outlet connecting with a conduit for transporting gas from the gas outlet to atmosphere, means for detecting a rate of gas flowing through the gas inlet and means for forcing an oxidising gas to flow from the gas inlet via the container, the gas outlet and the conduit to atmosphere, a station for collecting particulate matter from gas flowing through the conduit and means for controlling the gas flow-forcing means in response to a detected gas flow rate at the gas inlet, wherein the rate of gas flow at the gas inlet is maintained at a desired rate to provide substoichiometric fuel combustion within the container, thereby to promote particulate matter formation. 
     
     
         2 . An apparatus according to  claim 1 , wherein the gas flow-forcing means draws gas into the container gas inlet. 
     
     
         3 . An apparatus according to  claim 2 , wherein the gas flow-forcing means comprises a fan, optionally located between the station for collecting particulate matter and a conduit exit to atmosphere. 
     
     
         4 . An apparatus according to  claim 3 , wherein the conduit between the station for collecting particulate matter and the conduit exit to atmosphere comprises a heat exchanger, optionally an air-cooled or water-cooled radiator, for reducing the temperature of exhaust gas contacting the fan. 
     
     
         5 . An apparatus according to  claim 1 , wherein the gas flow-forcing means drives gas through the gas inlet. 
     
     
         6 . An apparatus according to  claim 5 , wherein the gas flow-forcing means comprises a pump. 
     
     
         7 . An apparatus according to  claim 1 , wherein a length of the conduit located between the container gas outlet and the station for collecting particulate matter is from 5 to 50 times a diameter of the conduit. 
     
     
         8 . An apparatus according to  claim 1  further comprising means, when in use, for controlling a rate of fuel flowing into the fuel burner and means, when in use, for controlling the temperature of the fuel flowing into the fuel burner. 
     
     
         9 . An apparatus according to  claim 1 , wherein in addition to the nozzle the fuel burner comprises a fuel pump, means for igniting fuel and a safety cut out. 
     
     
         10 . An apparatus according to  claim 1 , wherein the nozzle is designed to produce a solid cone spray distribution pattern of fuel droplets. 
     
     
         11 . An apparatus according to  claim 1 , wherein the nozzle is positioned vertically. 
     
     
         12 . An apparatus according to  claim 1 , wherein an injector is located within the conduit. 
     
     
         13 . An apparatus according to  claim 1 , wherein the station for collecting particulate matter is adapted to receive a catalyst substrate monolith or a filter. 
     
     
         14 . An apparatus according to  claim 1  further comprising means for determining a pressure drop across the station for collecting particulate matter, optionally comprising a differential pressure sensor, one tapping located on an upstream side of the station, another tapping located on a downstream side of the station. 
     
     
         15 . An apparatus according to  claim 14  further comprising means, when in use, for controlling the gas flow-forcing means in response to information from the pressure drop determining means in addition to controlling the gas flow-forcing means in response to a detected gas flow rate at the gas inlet. 
     
     
         16 . An apparatus according to  claim 15 , wherein the control means comprises an electronic control unit (ECU). 
     
     
         17 . An apparatus according to  claim 1  further comprising means for sensing the temperature of the gas as it flows through the apparatus, optionally a thermocouple. 
     
     
         18 . A method of generating and collecting particulate matter derived from combusting liquid carbon-containing fuel in an oxidising gas, which method comprising the steps of burning the fuel in a substoichiometric quantity of oxidising gas in a fuel burner, said fuel burner comprising a nozzle, which nozzle being housed in a container, forcing an oxidising gas to flow from a gas inlet to the container to atmosphere via a gas outlet to the container and a conduit connected to the gas outlet, collecting particulate matter at a station located within the conduit, detecting a rate of oxidising gas flow at the gas inlet and controlling the rate of oxidising gas flow so that a desired rate of oxidising gas flow is maintained at the gas inlet. 
     
     
         19 . A method according to  claim 18 , wherein the fuel burner burns hydrocarbon fuels and oxygenated fuels. 
     
     
         20 . A method according to  claim 19 , wherein the fuel burner burns standard automotive fuel, optionally diesel fuel or gasoline. 
     
     
         21 . A method according to  claim 18 , wherein the fuel burner burns at least one exhaust gas precursor compound in addition to hydrocarbon fuels and oxygenated fuels. 
     
     
         22 . A method according to  claim 18  further comprising injecting at least one exhaust gas precursor compound into the conduit, wherein the at least one compound injected into the conduit at least partially decomposes within the gas exiting the container before it reaches the station for collecting particulate matter. 
     
     
         23 . A method according to  claim 21 , wherein the exhaust gas precursor compound/s comprise amines, organosulphur compounds, or both amines and organosulphur compounds. 
     
     
         24 . A method according to  claim 18  further comprising injecting at least one exhaust gas component into the conduit upstream of the station for collecting particulate matter. 
     
     
         25 . A method according to  claim 18 , comprising generating particulate matter at a rate of from 1.0 to 20.0 g/hr, optionally from 1.0 to 3.5 g/hr. 
     
     
         26 . A method according to  claim 18 , wherein the temperature of gas flowing into the station for collecting particulate matter is from 100 to 300° C., optionally from 100 to 225° C. 
     
     
         27 . A method according to  claim 18  further comprising cooling the gas exiting the station for collecting particulate matter using a heat exchanger, optionally an air-cooled or water-cooled radiator. 
     
     
         28 . A method of combusting a liquid carbon-containing fuel to generate particulate matter for laboratory analysis, which method comprising the steps of generating a fine mist spray of droplets of fuel surrounded by a flowing stream of oxidising gas in a combustion can to generate a flowing rich combustion mixture, igniting the flowing rich combustion mixture in the combustion can and continuing to combust the flowing rich combustion mixture as it exits the combustion can, wherein the combustion mixture exiting the combustion can is made leaner as it becomes mixed with substantially non-turbulent entrained air. 
     
     
         29 . A method according to  claim 28 , wherein hydrocarbon fuels and oxygenated fuels are combusted in the combustion can. 
     
     
         30 . A method according to  claim 28 , wherein at least one exhaust gas precursor compound is combusted in the combustion can in addition to hydrocarbon fuels and oxygenated fuels. 
     
     
         31 . An apparatus for use in the method according to  claim 28 , which apparatus comprising a nozzle for spraying a fine mist spray of droplets of carbon-containing fuel into a combustion can comprising an exhaust port, means for producing a stream of oxidising gas to surround the fuel spray and means for igniting the fuel spray as it exits the nozzle. 
     
     
         32 . An apparatus according to  claim 31 , wherein the nozzle is designed to produce a solid cone spray distribution pattern of fuel droplets. 
     
     
         33 . An apparatus according to  claim 31 , wherein the nozzle is positioned vertically.