Combustion gas purifier and internal combustion engine

Abstract

A small capacity pre-catalytic system ( ) is disposed immediately downstream of an exhaust port ( ), and a large capacity main catalytic system ( ) is disposed immediately downstream of the pre-catalytic system ( ). The pre-catalytic system ( ) includes finely divided catalyst supports ( ), and a third stage heat exchanger (H ) is disposed between these catalyst supports ( ) so that a heat transfer tube ( ) is bent in a zigzag manner. Fourth stage and fifth stage heat exchangers (H , H ) are disposed on the upstream side, in the flow of the exhaust gas, of the pre-catalytic system ( ), and first and second stage heat exchangers (H , H ) are disposed on the downstream side, in the flow of the exhaust gas, of the main catalytic system ( ). Water is made to flow through the first stage heat exchanger (H ) to the fifth heat exchanger (H ) in a direction opposite to that in which the exhaust gas flows, thereby exchanging heat with the exhaust gas. This allows the catalyst temperature to be actively controlled within the optimal temperature range without degrading the energy efficiency of the entire system.