Device for recovering residual heat from exhaust gas

Abstract

A device for recovering residual heat from exhaust gas includes: a dry economizer which heats to-be-heated water by utilizing sensible heat of the exhaust gas, the dry economizer being provided in a duct extending to a funnel through which the exhaust gas is emitted to atmosphere; and a condensation economizer which heats to-be-heated water by utilizing latent heat of condensation of the exhaust gas, the condensation economizer being provided on a downstream side of the dry economizer. The duct includes an upstream duct in which the dry economizer is provided and a downstream duct connected to the upstream duct and directing the exhaust gas to flow upwardly. The condensation economizer is arranged in the downstream duct so that temperature of the exhaust gas amounts to condensation temperature at a vicinity of an upper part of the condensation economizer.

1 . A device for recovering residual heat from exhaust gas, the device comprising:
 a dry economizer which heats to-be-heated water by utilizing sensible heat of the exhaust gas, the dry economizer being provided in a duct extending to a funnel through which the exhaust gas is emitted to atmosphere; and   a condensation economizer which heats to-be-heated water by utilizing latent heat of condensation of the exhaust gas, the condensation economizer being provided on a downstream side of the dry economizer,   wherein the duct comprises an upstream duct in which the dry economizer is provided and a downstream duct connected to the upstream duct and directing the exhaust gas to flow upwardly, and   wherein the condensation economizer is arranged in the downstream duct so that temperature of the exhaust gas amounts to condensation temperature at a vicinity of an upper part of the condensation economizer.   
     
     
         2 . The device for recovering residual heat according to  claim 1 , further comprising:
 a white-smoke detector which detects white smoke of the exhaust gas emitted to the atmosphere through the funnel;   a heater which heats the exhaust gas on a downstream side of the condensation economizer in a flow direction of the exhaust gas by heat transfer from the exhaust gas in the upstream duct to the downstream side of the condensation economizer; and   a heating controller which controls heating condition of the heater based on detection result of the white-smoke detector.   
     
     
         3 . The device for recovering residual heat according to  claim 2 ,
 wherein the heater is a gas heater which comprises: a heat recovery section at which residual heat of the exhaust gas is recovered by a heat exchanger plate on a downstream side of the dry economizer in the flow of the exhaust gas; and a reheating section at which the exhaust gas is reheated on the downstream side of the condensation economizer by the residual heat having been recovered by means of the heat exchanger plate at the heat recovery section, the gas heater rotating the heat exchanger plate so as to be placed in the heat recovery section and the reheating section alternately, and   wherein the heating controller increases a rotational speed of the heat exchanger plate with increase in concentration of the white smoke based on the detection result of the white-smoke detector.   
     
     
         4 . The device for recovering residual heat according to  claim 2 ,
 wherein the heater comprises: a bypass channel through which the upstream duct is in communication with the downstream duct so that a portion of the exhaust gas in the upstream duct flows into the downstream side of the condensation economizer; and a damper which adjusts flow rate of the portion of the exhaust gas flowing in the bypass channel, and   wherein the heating controller increases an opening amount of the damper with increase in concentration of the white smoke based on the detection result of the white-smoke detector.   
     
     
         5 . The device for recovering residual heat according to  claim 1 , further comprising:
 a spray nozzle which sprays water to the exhaust gas flowing in the condensation economizer,   wherein the water sprayed to the exhaust gas by the spray nozzle has temperature between an inlet temperature and an outlet temperature of the to-be-heated water in the condensation economizer.   
     
     
         6 . The device for recovering residual heat according to  claim 1 , wherein the to-be-heated water flows in the dry economizer and the condensation economizer in a direction that is opposite to a direction of the exhaust gas. 
     
     
         7 . The device for recovering residual heat according to  claim 2 , further comprising:
 a spray nozzle which sprays water to the exhaust gas flowing in the condensation economizer,   wherein the water sprayed to the exhaust gas by the spray nozzle has temperature between an inlet temperature and an outlet temperature of the to-be-heated water in the condensation economizer.   
     
     
         8 . The device for recovering residual heat according to  claim 3 , further comprising:
 a spray nozzle which sprays water to the exhaust gas flowing in the condensation economizer,   wherein the water sprayed to the exhaust gas by the spray nozzle has temperature between an inlet temperature and an outlet temperature of the to-be-heated water in the condensation economizer.   
     
     
         9 . The device for recovering residual heat according to  claim 4 , further comprising:
 a spray nozzle which sprays water to the exhaust gas flowing in the condensation economizer,   wherein the water sprayed to the exhaust gas by the spray nozzle has temperature between an inlet temperature and an outlet temperature of the to-be-heated water in the condensation economizer.