What does "Secondary Fuel Type : Not approved for secondary fuel use" mean on the ENEFEN report?
Our statement: " Secondary Fuel Type : Not approved for secondary fuel use ...." means that we know that secondary fuel(s) will be used but we cannot determine at this stage if it will be done in a safe manner. In other words we do not know what will happen when you add secondary fuel(s) and we do not want to be liable for allowing you to do that. Once you add another fuel you have the choice to either get us back to augment the field approval to use secondary fuel(s) or use the system at your own risk.
At this point you are not required in Alberta to obtain a field approval for fuels other than natural gas or propane, unless the use of these fuels affects safety of the natural gas or propane fired system.
The objective of a Field Approval is to have a SAFE appliance.Therefore we have to look at all aspects which may affect safety. The B149 codes are indeed limited to natural gas, propane and some other gases, however, they also include other requirements such as pre-purge, trial for ignition, fuel shutoff, etc.
When it comes to "other" flammable substances or streams which may be present inside an appliance, they clearly cannot be ignored when considering safety. This applies to streams such as waste gases, liquid fuels and also solid fuels (dust) such as wood, biomass or coal.
With a Kiln for example, it would not be safe to try pilot ignition in an appliance which is full of explosive gas or pulverized coal dust. Also the pre-purge would be meaningless if these "other" fuels were kept going. If you have not submitted anything on how this will be done we cannot determine if it will be done in a safe manner. We would need to know if there will also be other fuels. Although the natural gas control system is separate from another system it may not be entirely so. If natural gas is needed to preheat a kiln prior to introduction of coal, and if the control system switches back to natural gas in case of coal supply failure then the systems are not completely separate. There are very likely interlocks between the systems which affect pre-purge sequence, timing, trips, temperatures, etc. In this sense the application is in our eyes not that much different from other process equipment such as reaction furnaces or waste gas incinerators.
Previous experience with kilns has shown appliances typically had a natural gas pilot (base gun) which was kept going after the switch to another fuel. In a few cases we have seen natural gas added directly to the pulverized coal burner to improve and stabilize mixture flammability. So the natural gas control system was operating simultaneously to the coal delivery system. Which means that the UV scanner kept looking at the natural gas flame while the IR scanner looked at the coal flame. A system trip would affect both. Then a restart would also involve both systems.
For questions specific to your equipment you may contact Susan at 780-665-2863 ext. 17 or email sb[email protected]