Flue gas conditioning system

A system for conditioning flue gas with sulfur trioxide for removal of entrained particles with an electrostatic precipitator, comprising:

• means for providing a flow of sulfur dioxide in air at a desired temperature, including a sulfur burner, a pump for liquified sulfur, means for providing a heated flow of air to said sulfur burner, a temperature sensor for flow of sulfur dioxide in air and a control connected with said temperature sensor and said sulfur pump to vary the operation of said sulfur pump and maintain the flow of sulfur dioxide in air at a setpoint corresponding to the desired temperature;
• catalytic converter means for converting sulfur dioxide to sulfur trioxide;
• means for generating a sulfur trioxide demand signal;
• and
• a controller connected with said means for generating a sulfur trioxide demand signal and said means for providing a heated flow of air to said sulfur burner, said controller operating said means for providing a heated flow of air to said sulfur burner in response to a sulfur trioxide demand signal to provide cooling inputs to said sulfur burner for increased sulfur trioxide flows and heating inputs to said sulfur burner for decreased sulfur trioxide flows.

A method for conditioning flue gas with sulfur trioxide for removal of entrained particles with an electrostatic precipitator, comprising the steps of:

• supplying air through a sulfur burner start-up heater to pre-heat a sulfur burner to the combustion temperature of sulfur;
• initiating a flow of liquid sulfur to said sulfur burner in proportion to a sulfur trioxide demand signal to provide a flow of sulfur dioxide to a catalytic converter for conversion to sulfur trioxide;
• de-energizing the sulfur burner start-up heater;
• adjusting air flow through the sulfur burner in response to the sulfur trioxide demand;
• and
• adjusting the sulfur flow to maintain a satisfactory operating temperature in said catalytic converter.

In a method for conditioning flue gas with sulfur trioxide for removal of entrained particles with an electrostatic precipitator in which flows of air and sulfur are supplied to a sulfur burner for combustion to create a flow of sulfur dioxide and air from the sulfur burner directed to a catalytic converter for conversion to a sulfur trioxide conditioning agent, the improvement comprising the steps

• providing a sulfur trioxide demand signal;
• adjusting the air flow to the sulfur burner in response to the sulfur trioxide demand signal;
• sensing a temperature of the flow of sulfur dioxide and air from the sulfur burner;
• and
• adjusting the sulfur flow to the sulfur burner to maintain the temperature of the flow of sulfur dioxide from the sulfur burner to provide an effective operating temperature range of the catalytic converter and a demanded flow of sulfur trioxide.

In a method for conditioning flue gas with sulfur trioxide for removal of entrained particles with an electrostatic precipitator in which flows of heated air and sulfur are supplied to a sulfur burner for combustion to create a flow of sulfur dioxide and air directed to a catalytic converter for conversion to a sulfur trioxide conditioning agent, the improvement comprising the steps of:

• providing a sulfur trioxide demand signal;
• adjusting the temperature of the air flow to the sulfur burner in response to the sulfur trioxide demand signal;
• sensing a temperature of the flow of sulfur dioxide and air from the sulfur burner;
• and
• adjusting the sulfur flow to the sulfur burner to maintain the temperature of the flow of sulfur dioxide from the sulfur burner to provide an effective operating temperature of the catalytic converter and a demanded flow of sulfur trioxide.

A method for conditioning flue gas with conditioning agent for removal of entrained particles with an electrostatic precipitator having at least one charging electrode intermittently charged and discharged and at least one collection electrode, comprising the steps of:

• determining a discharge rate of said charged electrode;
• generating a discharge rate signal relating to said discharge rate;
• generating a sulfur trioxide demand signal from said discharge rate signal to provide for a flow of sulfur trioxide for conditioning flue gas;
• supplying air through a sulfur burner start-up heater to pre-heat a sulfur burner to the combustion temperature of sulfur;
• supplying air through a catalytic converter heater to pre-heat catalytic converter to a temperature range of 750.degree. F. and 1000.degree. F.;
• initiating a flow of liquid sulfur to said sulfur burner in response to the sulfur trioxide demand signal to provide a flow of sulfur dioxide to the catalytic converter for conversion to sulfur trioxide;
• de-energizing the sulfur burner start-up heater upon initiation of sulfur flow;
• diverting said air flow from said catalytic converter heater around said catalytic converter upon initiation of sulfur flow;
• determining a desired temperature for said flow of sulfur dioxide to the catalytic converter;
• determining the temperature of the flow of sulfur dioxide;
• adjusting air flow through the sulfur burner in response to the sulfur trioxide demand;
• and
• adjusting the sulfur flow to maintain said flow of sulfur dioxide within acceptable limits for said desired temperature.

A flue gas conditioning system for controlling the flow of conditioning agent for removal of conditioned entrained particles in the flue gas with an electrostatic precipitator having at least one charging electrode and at least one collection electrode, comprising:

• signal means for providing a decay rate signal related to a discharge rate of said charged electrode after current supplied to said charged electrode is interrupted;
• means for providing a flow of sulfur dioxide gas in air at a desirable temperature, including a sulfur burner, means for providing said sulfur burner with a flow of air, and means for providing said sulfur burner with a flow of sulfur;
• catalytic converter means for converting sulfur dioxide to sulfur trioxide;
• temperature sensor means for the flow of sulfur dioxide and air from said sulfur burner to said catalytic converter means;
• sulfur trioxide demand input means coupled to said decay rate signal for providing a signal corresponding to a demand for sulfur trioxide;
• and
• a controller coupled to said means for providing the sulfur burner with a flow of air and to said sulfur trioxide demand input means, said controller being programmed to operate said means for providing said sulfur burner with a flow of air to vary the sulfur burner input conditions in response to said decay rate signal and operating temperature of said catalytic converter means.

A method for conditioning flue gas with sulfur trioxide for removal of entrained particles with an electrostatic precipitator, comprising the steps of:

• supplying air through a sulfur burner start-up heater to pre-heat a sulfur burner to the combustion temperature of sulfur;
• supplying air through a catalytic converter start-up heater to pre-heat catalytic converter means to a temperature range of 750.degree. and 1000.degree.;
• initiating a flow of liquid sulfur to said sulfur burner;
• de-energizing the sulfur burner start-up heater;
• diverting said air flow from said catalytic start-up heater around said catalytic converter means;
• providing a sulfur trioxide demand signal;
• adjusting air flow through the sulfur burner in response to the sulfur trioxide demand signal;
• adjusting the sulfur flow to maintain a satisfactory operating temperature in said catalytic converter means and satisfy the sulfur trioxide demand signal.