Oxy/fuel combustion system having combined convective section and radiant section

Abstract

A heat transfer system having a a radiant source, a first heat exchanger configured to permit a first fluid to flow therethrough, and a thermal shield configured to provide controlled radiative heat from the radiant source to the first exchanger. The radiant source is a flame. The thermal shield is a second heat exchanger configured to permit a second fluid to flow therethrough or a non-contact thermal shield fabricated from a material arranged to provide controlled radiative heat exposure from the radiant source to the first exchanger. Oxy / coal combustion systems are also disclosed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This Application is related to application Ser. No. ______, entitled “OXY / FUEL COMBUSTION SYSTEM WITH LITTLE OR NO EXCESS OXYGEN”, Attorney Docket No. 07228 USA, filed contemporaneously with this application on Sep. 26, 2008, assigned to the assignee of the present disclosure and which is herein incorporated by reference in its entirety, application Ser. No. ______, entitled “COMBUSTION SYSTEM WITH STEAM OR WATER INJECTION”, Attorney Docket No. 07238 USA, filed contemporaneously with this application on Sep. 26, 2008, assigned to the assignee of the present disclosure and which is herein incorporated by reference in its entirety, application Ser. No. ______, entitled “COMBUSTION SYSTEM WITH PRECOMBUSTOR”, Attorney Docket No. 07255 USA, filed contemporaneously with this Application on Sep. 26, 2008, assigned to the assignee of the present disclosure and which is herein incorporated by reference in its entirety, application Ser. No. ______,...

AI Technical Summary

Benefits of technology

[0008]This disclosure provides a boiler design that does not require flue gas recycle to achieve the correct heat distribution to superheat and reheat steam, achieves lower overall cost, permits superheating of at least a portion of the steam in the radiant section of an oxy / solid fuel boiler, and / or adequately protects the superheat tubes from the high heat fluxes prevailing in the radiant section.

[0012]An advantage of the present disclosure is not requiring flue gas recycle to achieve the correct heat distribution to superheat and reheat steam. The reduction or elimination of recycle permits reduction in the size or elimination of the convection section and boiler and therefore decreases the overall capital and operating cost of the system.

[0013]Another advantage of the present disclosure is lower overall cost.

[0015]Yet another advantage of the present disclosure is providing increased protection of the superheat tubes from the high heat fluxes prevailing in the radiant section.

[0016]Yet another advantage of the present disclosure is reduced flue gas recycle without increasing temperature at which gases exit the radiant section thereby reducing the propensity for convective pass fouling as well as maintaining the heat and mass balance for a given turbine cycle.

Problems solved by technology

Superheat steam tubes are important in efficient boiler operation but are not able to accept heat fluxes as high as water tubes due to decreased thermal heat capacity per unit volume.

Known systems do not provide protection for superheat tubes from the high heat fluxes prevailing in the radiant section.

Unprotected steam tubes exposed to high heat fluxes are subject to damage and / or failure.

Using FGR to transfer heat increases the complexity of the flue gas handling system, the size of the convection section and boiler and therefore increases the overall capital and operating cost of the system.

Another challenge for oxy / coal combustion is the furnace exit gas temperature.

In an oxy / coal combustion arrangement utilizing a convective heat exchange section, less heat is available for superheating the steam, due, in part, to a constraint on the temperature of the gases exiting the radiant section of the boiler, causing an imbalance in the heat available for transfer to feedwater, steam generation, and superheating.

Recycling the flue gas adds overall capital and operating cost of the overall process.

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