What is Composite Boiler And Exhaust Boiler

 Exhaust gas boiler

  The exhaust gas boiler and economizer are heat recovery units . The exhaust gas from the main engine is used to heat water in the tubes at a specific temperature and limited pressure loss.

    In the fig above shows a simple and commonly used Exhaust gas system, In this exhaust gas boiler consists solely of an evaporator section. The feed water is pumped directly to the oil-fired boiler which is used as a common steam drum for the oil-fired boiler and the exhaust gas boiler. Using circulating pump water is getting circulated through economiser and back to the steam drum of oil fired boiler

      Because of its simplicity and low capital cost, the above system is widely used and is often entirely adequate when the steam production is viewed as a means of meeting the steam demand for heating services on the ship.

Composite boiler

     Composite boilers are combination of oil-fired boilers and exhaust gas economizers. When the diesel engine is at full load the fuel oil burner only starts if the steam demand exceeds the steam production achieved from the diesel engines exhaust gases.

    A composite boiler can be a water tube or a smoke tube boiler divided in two different sections. One section of the boiler is heated by the burner and the other by the exhaust gases produced by the ship's engine.