PRODUCT INFORMATION
INDEX
DATE
Dep. 2
IC-C-D-40-003e A
May 2012
OXIDATIVE CATALYTIC CONVERTERS
3/6
-
The quality of the natural gas must be as specified in documents IP-GD-30 IC-001 and IC-GD-IP 30-002 on
natural gas fuel. There must be no leaks from the exhaust system.
-
There must be a minimum of 4% by volume of oxygen in the exhaust gas at the oxidative catalytic converter
inlet.
-
The pressure drop in the catalytic converter should be no more than 0.5 kPa above the initial pressure drop in
the catalytic converter. If this occurs ash deposits are being produced on the surface of the catalytic converter
and it must be cleaned.
3. OPERATING THE CATALYTIC CONVERTER
The oxidative catalytic converter is designed to convert the main unburnt fractions of the engine exhaust gases:
carbon monoxide (CO), hydrocarbons (CxHy) and partially oxidised hydrocarbons (CxHyO) to the typical products
of perfect combustion: carbon dioxide (CO2) and water (H2O).
These oxidation reactions are exothermic (they produce heat), meaning that the catalyser outlet temperature is
higher than the inlet temperature. The
T value throughout the catalytic converter depends on several factors,
such as the amount of contaminant available or the degree of efficiency of the catalytic converter, but the
temperature rise is normally below 40ºC.
The temperature of the exhaust gases within the catalytic converter is a very important factor with regard to
obtaining a high degree of conversion efficiency. In general, the higher the temperature, the greater the efficiency
obtained by the catalytic system, depending on the pollutant being treated. Below you can see the typical
recommended values and limits for temperature and pollutants in the exhaust gas to optimise the efficiency of
oxidative catalytic converters.
Fuel type
Pollutant type
Minimum temperature
Exhaust composition limit
Any fuel
CO
400ºC
-
Natural Gas
NMHCs, including
formaldehyde
(no methane)
450ºC
Ethane < 40% weight NMHCs
propane < 50% weight NMHCs
Natural Gas
NMNEHCs
(no methane, no
ethane)
425ºC
Propane < 10% weight NMNEHCs
Natural Gas
VOCs
425ºC
-
Natural Gas
CH
2
O
(formaldehyde)
425ºC
-
LPG
(Liquid Petroleum Gas)
THCs
(totals)
450ºC
Propane < 30% weight THCs
Diesel
THCs
400ºC
NMHCs: Hydrocarbons (no methane)
NMNEHCs: Hydrocarbons (no methane, no ethane)
VOCs: Volatile Organic Compounds.
THCs: Total hydrocarbons.
CH
2
O: Formaldehyde.
Table 2. Optimal working temperatures of the catalytic converter
2.7.3
O&M_2.002211.810_A_10_2016
