Dual-Fuel DOC Regeneration via Exhaust Gas Cycling

The patent applies periodic action by cycling the DOC through alternating oxidation and reduction phases. During oxidation phases, the catalyst operates at high temperatures to convert hydrocarbons. During reduction phases, the temperature is lowered or reducing conditions are introduced to convert PdO back to Pd, preventing permanent degradation. This periodic cycling maintains catalyst effectiveness over time despite the harsh operating conditions of dual-fuel engines.

The patent employs parameter changes by dynamically adjusting operational parameters such as temperature, oxygen concentration, and hydrocarbon injection timing to control the oxidation state of the Pd catalyst. By changing these parameters, the system optimizes the balance between maintaining catalytic activity (requiring PdO) and preventing excessive oxidation that leads to degradation (requiring Pd), thereby resolving the contradiction between productivity and reliability.

The patent applies self-service by utilizing the engine's own exhaust gas composition and operational cycles to regenerate the DOC, without requiring external hydrocarbon insertion systems. The natural fluctuations in exhaust gas composition during normal engine operation (including brief rich excursions) are harnessed to provide reducing conditions that convert PdO back to Pd, allowing the system to self-regenerate the catalyst using resources already present in the system.

The patent demonstrates universality by designing a regeneration approach that uses the existing dual-fuel engine system components for multiple purposes: the exhaust gas flow serves both as the medium to be treated and as the regenerating agent for the catalyst. The fuel injection system, already necessary for engine operation, is also utilized to provide the hydrocarbon-rich conditions needed for catalyst regeneration, eliminating the need for dedicated regeneration hardware.