US 6,521,021 B1 · Thief process for the removal of mercury from flue gas

Abstract

A system and method for removing mercury from the flue gas of a coal-fired power plant is described. Mercury removal is by adsorption onto a thermally activated sorbent produced in-situ at the power plant. To obtain the thermally activated sorbent, a lance (thief) is inserted into a location within the combustion zone of the combustion chamber and extracts a mixture of semi-combusted coal and gas. The semi-combusted coal has adsorptive properties suitable for the removal of elemental and oxidized mercury. The mixture of semi-combusted coal and gas is separated into a stream of gas and semi-combusted coal that has been converted to a stream of thermally activated sorbent. The separated stream of gas is recycled to the combustion chamber. The thermally activated sorbent is injected into the duct work of the power plant at a location downstream from the exit port of the combustion chamber. Mercury within the flue gas contacts and adsorbs onto the thermally activated sorbent. The sorbent-mercury combination is removed from the plant by a particulate collection system.

Claims18

Dependent claims

A mercury removal system for removing mercury from a flue gas, comprising:

a combustion chamber having a combustion zone where a mixture of coal and air undergoes combustion;
means for removing a partially combusted stream of said mixture of coal and air directly from said combustion zone;
means for separating said partially combusted stream of said mixture of coal and air into a gas recycle stream and a thermally activated sorbent stream;
a flue gas transport duct where said duct is coupled to an exit port of said combustion chamber and where said duct carries a flue gas stream away from said combustion chamber;
means for contacting said thermally activated sorbent stream with a flow of the flue gas at a downstream location relative to said combustion chamber;
and
means for removal of said thermally activated sorbent stream containing said mercury.

4 more elements

A method for removing mercury from a flue gas of a coal fired power plant by use of a thermally activated sorbent created in-situ, comprising the steps of:

injecting a pulverized coal and air mixture into a combustion chamber;
extracting a stream of semi-combusted pulverized coal and gas directly from a combustion zone within said combustion chamber;
separating said stream of semi-combusted pulverized coal and gases into a gas recycle stream and a thermally activated sorbent stream;
re-injecting said gas recycle stream into said combustion chamber, or other downstream location;
cooling said thermally activated sorbent;
contacting said thermally activated sorbent with the flue gas at a location downstream from said combustion chamber within the power plant where the mercury removal results from the contacting of said thermally activated sorbent with the flue gas;
and
collecting said thermally activated sorbent containing an amount of mercury removed from the flue gas in a particulate collection device.

5 more elements

Dependencies are inferred from the claim text.

Thief process for the removal of mercury from flue gas

Life of this patent

Thief process for the removal of mercury from flue gas

Life of this patent

Abstract

Claims18