Alcoa Inc.

Jay N Bruggeman

Robert B Hosler

Xiangwen Wang

Gary P Tarcy

Ron D Barclay

Rajat S Ghosh

Neal Richard Dando

Michael Lewis Slaugenhaupt

Patrick J O'Connor

Patrick J O'connor

Horizontal duct scrubbing systems for removing particulate matter from a gas are disclosed. The horizontal scrubbing systems may receive a particulate-containing gas stream (e.g., containing PM10 and/or PM2.5 particulate matter), and remove at least some of such particulates by spraying liquid droplets co-current to the flow of the gas stream, where the liquid droplets have a volume median droplet diameter (DV0.5) of from 240 microns to 600 microns. The scrubbing system may be substantially free of flow deflection members between a liquid inlet manifold and a demister. The system may be remove at least 50 wt. % PM10 and/or PM2.5 particulate matter from the gas stream.

Systems and methods for removing particulate matter from a gas stream

An electrolysis cell () contains a number of carbon anodes () having top, bottom and side surfaces, operating in molten electrolyte () in an aluminum electrolysis cell (), where gas bubbles () are generated at the anode surfaces and where alumina particles () are added to the top of the molten electrolyte, where the carbon anodes () have at least two inward slots () passing through the carbon anode () along the longitudinal axisof the carbon anode and also passing through only one front surface () of the carbon anode, where the height () of the slots () is from about 45% to 80% of the anodes thickness and the slotted front surfaces () are disposed toward the center of the electrolysis cell so that generated gas bubbles () are directed to the alumina particles.

Method for electrolytically producing aluminum using closed end slotted carbon anodes

An electrolysis cell () contains a number of carbon anodes () having top, bottom and side surfaces, operating in molten electrolyte () in an aluminum electrolysis cell (), where gas bubbles () are generated at the anode surfaces and where alumina particles () are added to the top of the molten electrolyte, where the carbon anodes () have one inward slot () passing through the carbon anode () along the longitudinal axisof the carbon anode and also passing through only one front surface () of the carbon anode, where the height () of the slot () is from about 45% to 80% of the anodes thickness and the slotted front surfaces () are disposed toward the center of the electrolysis cell so that generated gas bubbles () are directed to the alumina particles.

Closed end slotted carbon anodes for aluminum electrolysis cells

Operations in an electrolytic cell for producing aluminum are controlled by sensing infrared radiation on an outer surface of a cell chamber to determine an actual temperature. When the actual temperature is greater than a target temperature, a crust hole is repaired or the actual rate of addition of aluminum fluoride to the cell is increased. When the actual temperature is less than a target temperature, the actual rate of addition of aluminum fluoride to the cell is reduced.

Use of infrared imaging to reduce energy consumption and fluoride consumption

Operations in a cell for electrolytic production of aluminum are controlled by establishing a standard rate of addition of aluminum fluoride to a molten electrolyte covered by a crust; establishing a target temperature for a duct carrying offgas from a chamber containing the molten electrolyte; measuring an actual temperature in the duct; and, in response to the actual temperature measurement in the duct, performing at least one of (1) when the actual temperature is greater than the target temperature, inspecting the crust for a crust hole and then repairing any observed crust hole, and (2) varying an actual rate of addition of aluminum fluoride to the electrolyte by increasing the actual rate above the standard rate when the actual temperature is greater than the target temperature and by reducing the actual rate below the standard rate when the actual temperature is less than the target temperature. Controlling operations in accordance with the invention improves cell energy efficiency.

Measuring duct offgas temperatures to improve electrolytic cell energy efficiency

A method and apparatus for accurately measuring superheat, bath ratio and alumina concentration in an aluminum smelting bath. In one embodiment, a reusable probe determines the bath temperature and bath sample superheat. In other embodiments, the probe also determines bath composition including bath cryolite ratio and alumina concentration.

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Harrison City, PA, United States of America

Jay N Bruggeman