The Boc Group, Inc.

James K Tseng

Ravi Kumar Jain

Shuen-Cheng Hwang

Mark H Anderson

Robert Francis Workosky

Neeraj Saxena

Robert James Ferrell

Naresh J Suchak

Divyanshu R Acharya

Chester Gorski

Thulasidas Chellppannair

Lev Davydov

The present invention relates to a process for removing nitrogen oxides, sulfur oxides, mercury and mercuric oxide from gas streams such as furnace or utility boiler flue gas streams, particularly those derived from coal-fired utility boilers, or from a gas stream from another pollutant abatement process. Ozone will react with the impurities in the gas stream to form mercuric oxide and higher oxides of nitrogen which can be removed by scrubber means. Additionally, and alternatively, the present invention provides for the use of ozone and ultraviolet radiation to remove nitrogen oxides, sulfur oxides and mercury from gas streams.

Process for the removal of impurities from gas streams

The present invention relates to a process for removing nitrogen oxides from gas streams such as furnace or utility boiler flue gas streams. An adsorber system is used to adsorb nitrogen oxides from the flue gas streams. An oxygen/ozone gas stream contacts the nitrogen oxides to convert the nitrogen oxides to N O which will exit the adsorber with the oxygen stream.

Removal of nitrogen oxides from gas streams

Sulfur compounds present as sulfides and mercaptans in spent caustic streams from refinery and petrochemical processes are oxidized by contacting them with an oxygen-containing gas in a packed column recycle reactor.

Method for treating spent caustic streams

Nitric oxide is removed from a gas stream by contacting the gas stream with oxygen in the presence of a metal-cation exchanged zeolite, thereby oxidizing the nitric oxide to nitrogen dioxide, then contacting the resulting nitrogen dioxide-containing gas stream with ozone, thereby converting the nitrogen dioxide to nitric acid, nitric acid precursors or mixtures thereof, then contacting the gas stream with an aqueous liquid, thereby scrubbing the nitric acid, nitric acid precursors or mixtures thereof from the gas stream. Contact of the gas stream with oxygen in the presence of a zeolite is carried out at a temperature above the temperature at which significant adsorption of nitrogen dioxide occurs, and the aqueous liquid used as scrubbing agent preferably has a pH greater than 7.

Removal of nitric oxide from gas streams

The present invention relates to a process for removing nitrogen oxides from gas streams such as furnace or utility boiler flue gas streams. An ozone adsorption system is used to adsorb and concentrate ozone. A slip stream containing nitrogen oxides is introduced into an ozone adsorption system to desorb ozone and the ozone-containing slip stream gas is then directed to a reactor duct along with the primary nitrogen oxide-containing gas stream where the nitrogen oxides are converted to N.sub.2 O.sub.5.

Process for the removal of nitrogen oxides from gas streams

An argon gas stream containing hydrogen, carbon monoxide, water vapor, oxygen carbon dioxide, nitrogen and methane is purified by drying the gas stream with a desiccant, oxidizing the hydrogen and carbon dioxide to water vapor and carbon dioxide by contact with oxidizing catalysts in the presence of excess oxygen, removing the water vapor and carbon dioxide from the gas stream by adsorption, removing excess oxygen by chemisorption at elevated temperature and removing the nitrogen and methane by adsorption at cryogenic temperature. Alternatively, excess oxygen is removed from the gas stream by adsorption at a cryogenic temperature.

Process for argon purification

A method and apparatus for producing a clean dry air product stream. In accordance with the method and apparatus, a compressed feed air stream is introduced into one adsorption bed to adsorb moisture and carbon dioxide and to produce a first intermediate product stream. Impurities contained within the first intermediate product stream such as hydrocarbons, carbon monoxide and hydrogen are catalytically reacted to produce a second intermediate product stream that contains additional carbon dioxide and moisture produced from the catalytic reaction. The second intermediate product stream is introduced into another adsorption bed that adsorbs the additional moisture and carbon dioxide formed by the catalytic reaction to produce the clean dry air product stream. The present invention can be used alone to serve the need of supplying a clean dry air product stream. Additionally, it can be used as a prepurification unit of an air separation plant designed to produce an ultra-high purity industrial gas product. By catalytically reacting the hydrocarbons in the first intermediate product stream, less expensive oil lubricated compression equipment can be used to compress the feed air.

Method and apparatus for producing clean dry air having application to

An air prepurification process which includes, as a first step, a pressure swing adsorption process in which the air is passed through a bed of adsorbent which contains activated alumina, thereby effecting removal of substantially all moisture and most carbon dioxide from the feed air and as a second step, a temperature swing adsorption process in which the dried feed air is passed through a bed of carbon dioxide-selective adsorbent, thereby removing substantially all of the carbon dioxide remaining in the feed air. The feed air may be passed through beds of hydrogen oxidation and carbon monoxide oxidation catalysts between the first and second steps to convert any hydrogen and carbon monoxide in the feed air to water vapor and carbon dioxide, respectively, these components being removed from the feed air during the second step. The feed air may be optionally passed through a layer of a hydrocarbon selective adsorbent between the first and second steps to remove hydrocarbons such as ethylene, propylene and propane.

Air purification process

An air prepurification process carried out in a battery of three adsorption vessels arranged in parallel. The process includes three steps: a first step in which non-steady state PSA is carried out in the first and second vessels operated in alternating adsorption and bed regeneration mode while the adsorbent in the third vessel undergoes thermal regeneration; a second step in which non-steady state PSA is carried out in the second and third vessels operated in alternating adsorption and bed regeneration modes while the adsorbent in the first vessel undergoes thermal regeneration; and a third step in which non-steady state PSA is carried out in the first and third vessels operated in alternating adsorption and bed regeneration modes while the adsorbent in the second vessel undergoes thermal regeneration. Each vessel contains at least two adsorbent layers, including a first layer of activated alumina, which adsorbs substantially all moisture and some carbon dioxide from the feed air, and a second layer of zeolite, which adsorbs substantially all of the remaining carbon dioxide in the feed air. The feed air may be passed through beds of hydrogen oxidation and carbon monoxide oxidation catalysts positioned between the first and second layers, to convert any hydrogen and carbon monoxide in the feed air to water vapor and carbon dioxide, respectively, these components being removed from the feed air as it passes through the layer of zeolite.

An air prepurification system which includes vertically oriented adsorption vessels containing, from top to bottom, a layer of moisture-selective adsorbent, a first layer of carbon dioxide-selective adsorbent and a second layer of carbon dioxide-selective adsorbent wherein the particle size of carbon dioxide-selective adsorbent in the second layer of carbon dioxide-selective adsorbent is smaller than the particle size of both the moisture-selective adsorbent and the carbon dioxide-selective adsorbent in the first layer of carbon dioxide-selective adsorbent. The air purification system is designed for use in a temperature swing adsorption process in which air is passed downwardly through the adsorption vessels during the adsorption step and upwardly through the vessels during the adsorbent regeneration step.

Growing community of inventors

Berkeley Heights, NJ, United States of America

James K Tseng