System and Method for Full Combustion Optimization For Pulverized Coal-Fired Steam Boilers

Abstract

A method and system for controlling a pulverized coal fired boiler wherein the flow of a coal / air mixture flowing to each burner is monitored and transmitted to a distributed control system. The distributed control system also monitors and controls the position of dampers in a splitter that feeds the coal / air mixture to the burners. The dampers are controlled in a closed loop fashion to achieve a optimal boiler performance.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application is a national stage entry of PCT / US08 / 85671, which claims the priority to U.S. provisional patent application Ser. No. 61 / 012,089 filed on Jul. 12, 2007 entitled “ A System and Method for Full Combustion Optimization for Pulverized Coal-Fired Steam Boilers,” the contents of which are relied upon and incorporated herein by reference in their entirety.DESCRIPTION OF THE PRIOR ART[0002]There are a number of advanced control techniques for the optimization of combustion within a pulverized coal-fired boiler (PCFB). These methods typically involve the use of advanced model-predictive control, and / or neural net-based controls, to monitor, balance and control the admittance of fuel and air to various stages of the boiler, including primary, secondary, overfire, and underfire air controls. Other variables, such as burner tilts and attemperator spray flows may be controlled as well, in order to optimize the combustion process. As i...

AI Technical Summary

Benefits of technology

[0030]The advantages provided by the system of the present invention include, reductions in LOI (Loss on ignition—i.e. unburned fuel and wastage), reduced or eliminated use of auxiliary (co-firing) fuels during low loads, reduced waterwall wastage due to CO rich “dark zones”, and reduced emissions (CO2, CO and NOx). Further PCFB operational improvements which can result from the use of the present invention include, improved unit heat rate (thermal efficiency), improved unit ramp rate, improved flame and fireball stability over a much wider load range, elimination of some / all riffle boxes for fuel distribution, with improved draft fan efficiency results, and controllable variations in the air / fuel ratio to adapt to boiler load conditions.

Problems solved by technology

However, this optimization is in large part limited by physical process parameters that the system used to optimize combustion often does not have the ability to control.

Riffle boxes have been associated with high pressure drops which may lead to rapid-wear.

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