Reheating flue gas for selective catalytic systems
OwnerMitchell B. Coheninventor
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Abstract
A method and apparatus for controlling the temperature of a flue gas stream entering a Selective Catalytic Reduction chamber in a steam generating power plant that utilizes Selective Catalytic Reduction (SCR) to lower NO.sub.x emissions is disclosed. The method involves the utilization of superheated steam to control the temperature of the flue gas prior to the flue gas entering the Selective Catalytic Reduction chamber such that there is a reduction in lost energy to the thermodynamic steam cycle caused by spray desuperheating.
Claims16
A method of controlling the temperature of superheated steam in a fuel-fired steam generating power plant of the type having a thermodynamic steam cycle and a flue gas flow path acting in cooperative association therebetween, said method comprising the steps of:
- a. operating a first component of the thermodynamic steam cycle so as to produce thereby superheated steam at a first temperature and first pressure;
- b. operating a second component of the thermodynamic steam cycle downstream of the first component and upstream of a turbine thereof,
- the second component being operable to receive the superheated steam at a second temperature less than the first temperature;
- c. effecting an exchange of heat between the superheated steam and at least one heat exchange medium so as to thereby decrease the temperature of the superheated steam;
- and
- d. effecting the further processing of the at least one heat exchange medium and the further utilization of the superheated steam in the thermodynamic steam cycle.
A system for controlling the temperature of superheated steam in a fuel-fired steam generating power plant of the type having a thermodynamic steam cycle and a flue gas flow path acting in cooperative association therebetween, said system comprising:
- a. a first component of the thermodynamic steam cycle operative to produce thereby superheated steam at a first temperature and a first pressure;
- b. a second component of the thermodynamic steam cycle disposed downstream of the first component, the second component being operable to receive the superheated steam at a second temperature less than the first temperature;
- c. at least one heat exchange means for effecting an exchange of heat between the superheated steam produced by said first component and at least one heat exchange medium so as to thereby decrease the temperature of the superheated steam;
- d. means for forming a path for the flow of superheated steam from said at least one heat exchange means to said second component;
- and
- e. means for effecting the further processing of the at least one heat exchange medium after receiving heat from the superheated steam, said means for effecting the further processing of the at least one heat exchange medium being separate from said means forming a path for the flow of superheated steam from said at least one heat exchanger to said second component.
A method of controlling the temperature of a flue gas in a fuel-fired steam generating power plant of the type having a thermodynamic steam cycle and a flue gas flow path acting in cooperative association therebetween, said method comprising the steps of:
- a. operating a first component of the thermodynamic steam cycle so as to produce thereby superheated steam at a first temperature and first pressure;
- b. operating a second component of the thermodynamic steam cycle downstream of the first component and upstream of a turbine thereof,
- the second component being operable to receive the superheated steam at a second temperature less than the first temperature;
- and
- c. effecting an exchange of heat between the superheated steam and the flue gas so as to thereby decrease the temperature of the superheated steam;
- and
- d. effecting the further processing of the flue gas and the further utilization of the superheated steam in the thermodynamic steam cycle.
Dependencies are inferred from the claim text.