I have a situation with an existing asphalt plant rotary drier fired with a burner on LPG at 28GJ/Hr (26.5 x 10^6 BTU/hr). This was commissioned by me over 10 yrs ago. To this is to be added another rotary drier to dry RAP (Recycled Asphalt Payment) which is the old pulverized asphalt from old roads. This dried recycled product is supplemented into the new product. The RAP drier burner operates on diesel. Burner 23.3GJ/hr (22 x 10^6 BTU/hr).
The present LPG fired system exhausts via a large baghouse and uses an exhaust (ID) fan. Both of these have been upgraded to cater for the new RAP drier addition.
Hence the plan is to common both drier exhaust flues and concurrently they will flow through the baghouse and use the common ID fan.
The issue is that our Australian gas installation codes prohibit the coupling of the exhaust from "another" fuel into the gas fired burner exhaust flue. However we are able to seek an exemption from this clause with appropriate provisions. Personally I can see a problem arising with straight FD burners where there could be a possibility at certain relative firing rates for the exhaust of one feeding back or affecting the other. The "other" fuel emissions may not be regulated as is the gas burner. In my case we are always under a state of negative pressure ensuring the products of combustion always are drawn by the exhaust fan through the baghouse and out the chimney. I am also going to add a pressure switch at the connection point of the two flues to ensure there is always adequate suction at that point. If not the burners will be shut down.
At this stage our Gas authorities are reviewing my application. However certain people within the Authority have admitted that they don't understand the reasoning of the Clause prohibiting it without explanation. I can understand the concerns as stated above if purely a FD situation, but consider that if I ensure there is always adequate draft whilst both burners are in operation there should not be any problem.
Would appreciate any comments. See attachment of the combined system.
Rod Nissen.
Combustion & Engineering Diagnostics
The present LPG fired system exhausts via a large baghouse and uses an exhaust (ID) fan. Both of these have been upgraded to cater for the new RAP drier addition.
Hence the plan is to common both drier exhaust flues and concurrently they will flow through the baghouse and use the common ID fan.
The issue is that our Australian gas installation codes prohibit the coupling of the exhaust from "another" fuel into the gas fired burner exhaust flue. However we are able to seek an exemption from this clause with appropriate provisions. Personally I can see a problem arising with straight FD burners where there could be a possibility at certain relative firing rates for the exhaust of one feeding back or affecting the other. The "other" fuel emissions may not be regulated as is the gas burner. In my case we are always under a state of negative pressure ensuring the products of combustion always are drawn by the exhaust fan through the baghouse and out the chimney. I am also going to add a pressure switch at the connection point of the two flues to ensure there is always adequate suction at that point. If not the burners will be shut down.
At this stage our Gas authorities are reviewing my application. However certain people within the Authority have admitted that they don't understand the reasoning of the Clause prohibiting it without explanation. I can understand the concerns as stated above if purely a FD situation, but consider that if I ensure there is always adequate draft whilst both burners are in operation there should not be any problem.
Would appreciate any comments. See attachment of the combined system.
Rod Nissen.
Combustion & Engineering Diagnostics
