US 6,146,607 A · Process for producing highly reactive lime in a furnace

Abstract

A limestone furnace calcination process involves injecting finely divided limestone particles into a zone in a furnace at which the temperature of the flue gas stream, as it passes through the zone, is above the minimum calcination temperature and below the minimum effective quicklime utilization/sulfation temperature. In conventional furnaces, the minimum calcination temperature, or the calcium carbonate decomposition temperature, ranges from about 1,365 to 1,430.degree. F. The minimum effective quicklime utilization/sulfation temperature refers to the temperature below which the rate of quicklime sulfation of the lime produced by calcination of the limestone is sufficiently slow to result in negligible calcium sulfate formation on the resultant lime, and in conventional furnace applications ranges from 1,600 to 1,800.degree. F. The zone is preferably sized such that limestone particles injected therein will remain at a temperature above the minimum calcination temperature, as the particles are carried downstream, for a period sufficient for substantially complete calcination of the limestone particles to lime while minimizing reactions between the resultant lime particles and sulfur dioxide to form calcium sulfate while the particles are in the furnace and to minimize sintering of the lime and complex calcium compound formation. The resultant lime particles may then be utilized in conventional downstream flue gas desulfurization processes including wet and semi-dry processes.

Claims15

Dependent claims

A process for removing sulfur dioxide from the flue gas of a furnace, the furnace being of a type in which the flue gas including sulfur dioxide is produced from the combustion of sulfur-containing fuels;

said process comprising the step of:
(a) injecting finely divided particles of limestone into said furnace directly into the flue gas at a location at which the temperature of said flue gas passing therethrough exceeds the minimum calcination temperature and is below the minimum effective quicklime utilization/sulfation temperature so as to convert a portion of said limestone to lime in said furnace while limiting quicklime sulfation of said lime in said furnace;
and
(b) conveying said flue gas with said lime entrained therein out of said furnace to a downstream flue gas desulfurization system wherein said lime is utilized in the removal of sulfur dioxide from said flue gas.

1 more element

A process for removing sulfur dioxide from the flue gas of a furnace, the furnace being of a type in which flue gas including sulfur dioxide is produced from the combustion of sulfur-containing fuels;

said process comprising the steps of:
a) identifying a first set of operating conditions of said furnace including the concentration of sulfur dioxide, carbon dioxide and water vapor in the flue gas;
b) identifying a first minimum calcination temperature and a first minimum effective quicklime utilization/sulfation temperature for available limestone under said first set of operating conditions of said furnace;
c) identifying a first location within said furnace wherein the temperature of said flue gas passing therethrough approximately equals said first minimum effective quicklime utilization/sulfation temperature;
d) identifying a second location within said furnace wherein the temperature of said flue gas passing therethrough is approximately equal to said first minimum calcination temperature;
and
e) providing at least one first nozzle through which finely divided particles of said available limestone may be injected into said furnace;
f) positioning said first nozzle in close proximity to said first location such that when said furnace is operated under said first set of conditions injection of limestone through said first nozzle results in the calcination of a substantial portion of said limestone to lime while limiting quicklime sulfation of said lime in said furnace;
and
g) conveying said flue gas with said lime entrained therein out of said furnace to a downstream flue gas desulfurization system wherein said lime is utilized in the removal of sulfur dioxide from said flue gas.

7 more elements

Dependencies are inferred from the claim text.

Process for producing highly reactive lime in a furnace

Life of this patent

Process for producing highly reactive lime in a furnace

Life of this patent

Abstract

Claims15