Patent FR-2780507-A1 (FR)
Title: System for extracting specific pollutants from air diluted engine exhaust gases
Inventor: PASQUEREAU MICHEL
IPC: G01N1/00
Filed: 1998-06-26
Abstract: System for extracting specific pollutants from a diluted exhaust gas from a thermal combustion machine with a first module (1) dedicated to aldehyde and ketone emissions and a second module for hydrocarbon emissions. The system also contains means of coordinating the sampling(s) to preset operation phases of the thermal machine The first module contains a circuit (3) for trapping aldehydes and ketones from the dilute exhaust gas comprising a simulation passage parallel to the sampling passage, both with a common inlet (30) and outlet for the gas connected to a line containing a filter (35), a mass flow regulator (36) and a pump (37) in series.  A sampling circuit (4) for the diluting air is formed in the same way, with parallel passages, a common inlet (40) and a common outlet connected to a filter (45) a mass flow regulator (46) and a pump (47) in series. The first module also contains a purge circuit (6) to clean the two sampling circuits. The aldehyde and ketone trapping circuit contains at least one sampling cartridge (31) in the sampling passage. A control valve (32) is placed downstream of each sampling. The purge circuit comprises a general inlet (61) for the purge gas and two parallel passages (62, 63), one for each sampling circuit. Each passage contains a control valve (66, 67) near the inlet, and an element (64, 65) to fix the purge gas flow in the passage. The second module contains at least one general inlet for the diluted exhaust gases, at least a first passage containing a sampling bag and another parallel passage allowing gases to bypass the sampling bag; means of selecting which passage the exhaust gases pass into; a similar circuit for the dilution air with a general inlet and a sampling bag and bypass; and means of selecting which passage the diluting air passes into.  The second module also contains a circuit for purging one or more of the sampling bags by filling and emptying. The purge circuit contains a general inlet for the purge gas, a first control valve connected to the inlet, a pump and the parallel passages, a second control valve connected to an outlet, the pump and the parallel passages, and a connection with the parallel passages. It also contains a filter placed between the second control valve and the parallel passages to the bags, to purify the air during the bag filling operation. The means of directing the exhaust gases comprise a control valve placed on the gas circulation passage, a control valve on each passage with a sampling bag and a control valve upstream of the parallel passages. The means of directing the diluting air is similarly a control valve on the air circulation passages, a control valve (59) on each passage with a sampling bag and a control valve upstream of the parallel passages. The second sampling module contains two parallel passages near the general inlet, one for diesel gases and the other for controlled firing engines. The passage for the diesel gases includes a heated filter and an element for fixing the mass flow rate of the gases. The other passage contains an element for fixing the mass flow rate of the gases and a filter for impurities. Upstream of the parallel passages there is a pump and a flow meter. The diluting air feed line contains a filter, a pump and a controllable flow meter upstream of the parallel passages.