Compact dual-fuel combustion system, and fluid heating system and packaged burner system including the same

A method of burning two different fuels in a combustion burner during different operation times, comprising:

• providing a burner that can accept either a gaseous premix fuel-air mixture during gaseous premix fuel operation or a pre-heated and pre-pressurized liquid fuel oil during oil fuel operation, the burner having a porous substrate with an inner surface and an outer surface, the outer surface facing a combustion chamber, and having one or more oil nozzles disposed within the combustion cavity;
• during gaseous premix fuel operation, receiving the fuel-air mixture at the outer surface of the substrate, the fuel-air mixture passing through pores in the substrate from the substrate outer surface toward an opposite substrate inner surface, and igniting the fuel-air mixture near the pores to form flamelets, each flamelet corresponding to one of the pores;
• and
• during oil fuel operation, receiving, the pre-heated and pre-pressurized oil fuel at the one or more oil nozzles, dispersing, by the oil nozzles, the oil fuel into the combustion cavity such that the oil converts from a liquid oil state to a gaseous oil state through isenthalpic expansion in the combustion cavity, mixing the gaseous oil with air provided through the pores into the combustion cavity to create a gaseous oil-air mixture, and igniting the gaseous oil-air mixture in the combustion cavity

An inward-firing dual fuel combustion burner, comprising:

• a porous substrate having an inner surface and an opposite outer surface, the outer surface facing a combustion chamber, and having one or more oil nozzles disposed within the combustion cavity;
• the substrate configured to receive either air or a fuel-air mixture at the outer surface of the substrate, the air or fuel-air mixture passing through the porous substrate at a flow rate from the substrate outer surface toward the substrate inner surface;
• at least one oil nozzle disposed within the combustion cavity configured to receive pre-heated and pre-pressurized oil fuel and to disperse the oil fuel into the cavity;
• the burner configured to be operated using either a gaseous premix fuel air mixture during gaseous premix fuel operation or a pre-heated and pre-pressurized liquid fuel oil during oil fuel operation;
• the burner configured such that, during gaseous premix fuel operation, the fuel-air mixture is provided through the porous substrate into the combustion cavity and the fuel-air mixture ignites near pores in the porous substrate to form a respective plurality of flamelets in the combustion cavity, each flamelet corresponding to one of the pores;
• and
• the burner configured such that, during oil fuel operation, the pre-heated and pre-pressurized oil fuel is provided to the nozzles and the air is provided through the porous substrate into the combustion cavity such that the oil and air mixture in the combustion cavity ignites during isenthalpic expansion.