A novel method and device for the destruction of nitrous oxide in gases such as those resulting from exhaled breath during dental, medical, and veterinary procedures are described. The method employs processing steps including the collection of gases containing constituents such as water vapor, carbon dioxide, oxygen, nitrogen, and nitrous oxide from exhaled breath or from ambient room air, optional removal of moisture from the collected gas, catalytic decomposition of nitrous oxide gas to nitrogen and oxygen, heat exchange to reduce high temperatures in gases exiting the reactor, and sorbents to remove traces of reaction byproducts. Instrumentation and controls are employed to monitor and regulate temperatures, pressures, gas compositions, and flow rates while also providing measures to automatically shut down in the event of off-nominal conditions. The method and device are capable of operating with variable anesthetic or patient exhaled breath flow rates while inducing no significant pressure or vacuum on the patient as they exhale. The method is carried out in a compact device suitable for operation in dental offices, hospitals, and other locations where nitrous oxide is administered as an anesthetic.

A gas-liquid contacting apparatus and method are described, in which at least one rotor assembly including packing is arranged in a contacting chamber containing at least one stator assembly including at least one heat exchanger arranged to thermally modulate the gas-liquid contacting so that each stator assembly is operatively arranged with each stator assembly to provide gas-liquid contacting at temperatures effective for mass exchange between the gas and liquid. The rotor and stator assemblies may be of annular shape, or may be of disk shape in a stacked array of rotor assemblies alternating with stator assemblies. Such apparatus and method are usefully employed for CO.sub.2 capture from CO.sub.2-containing flue gases such as combustion effluents from power generation plants.

A process is presented where a feed stream containing a hydrogen sulfide and another feed component is introduced into an absorber that the feed stream flows upward from the bottom of the absorber and contacts a liquid treatment solution, where the liquid treatment solution contains a sulfur dye catalyst. The hydrogen sulfide is absorbed into the liquid treatment solution and converted into sulfide ions. The other feed component is removed from the absorber vessel substantially free of the hydrogen sulfide and a spent treatment solution is also removed from the absorber vessel and fed to an oxidation vessel where it is contacted with an oxygen containing gas causing the sulfide ions to oxidize to thiosulfate and converting the spent sulfur dye catalyst to regenerated sulfur dye catalyst. The thiosulfate is recovered, and the regenerated sulfur dye catalyst can be recycled as part of the liquid treatment solution.

Methods and systems for removing moisture from refrigerant that use a desiccant-based moisture removal unit can be used in the production of liquid natural gas (LNG). For example, a method can include: compressing a refrigerant; conveying at least a portion of the refrigerant to a moisture removal unit comprising a desiccant to form dehydrated refrigerant; cooling and condensing the dehydrated refrigerant to provide a cooled dehydrated liquid refrigerant; conveying the cooled dehydrated refrigerant to a heat exchanger; and passing a LNG stream rich in methane through the heat exchanger to cool at least part of the LNG stream by indirect heat exchange with the cooled dehydrated refrigerant.

Powdery calcium-magnesium compound, sorbent composition based on calcium-magnesium for being used in flue gas treatment, compatible with electrostatic precipitators and process for reducing the resistivity of a powdery sorbent composition for flue gas treatment installation comprising an electrostatic precipitator.

A flue gas desulfurization (FGD) system in which a buffering additive feed directly adds a buffering additive containing acetic acid to either the FGD sump or a stream of the system that is downstream of the sump. In a method for performing flue gas desulfurization, the buffering additive, containing acetic acid, is added to either the sump or the overflow. That is, the buffering additive is added to the FGD system separately from the alkaline feed slurry, which contains lime or limestone.

A process is presented where a feed stream containing a hydrogen sulfide and another feed component is introduced into an absorber that the feed stream flows upward from the bottom of the absorber and contacts a liquid treatment solution, where the liquid treatment solution contains a sulfur dye catalyst. The hydrogen sulfide is absorbed into the liquid treatment solution and converted into sulfide ions. The other feed component is removed from the absorber vessel substantially free of the hydrogen sulfide and a spent treatment solution is also removed from the absorber vessel and fed to an oxidation vessel where it is contacted with an oxygen containing gas causing the sulfide ions to oxidize to thiosulfate and converting the spent sulfur dye catalyst to regenerated sulfur dye catalyst. The thiosulfate is recovered, and the regenerated sulfur dye catalyst can be recycled as part of the liquid treatment solution.

Systems, apparatuses, and processes for controlling free ammonia in wet flue gas desulfurization processes in which an ammonia-containing scrubbing solution is used to produce ammonium sulfate. Such an apparatus includes an absorber having a contactor region through which a flue gas comprising sulfur dioxide is able to flow and a reaction tank containing a scrubbing solution containing ammonium sulfate. The tank has a sidewall and bottom wall that define the perimeter and bottom of the tank. Lance-agitator units are distributed around the perimeter of the tank, each having a lance that injects a mixture of oxygen and a dilute ammonia-containing fluid toward the bottom of the tank and an agitator that agitates the mixture and propels the mixture toward the bottom of the tank. The apparatus includes a source of the mixture of oxygen and dilute ammonia-containing fluid, and recirculates the scrubbing solution from the tank to the contactor region.

A pressure swing adsorption air dryer system and method is described herein. In some embodiments, the air dryer system receives moist air and dries the air using a desiccant in a pressure swing adsorption method. The resulting dry air may be used as a working fluid for an application and a portion of the dry air may be used to aid in regenerating, or removing moisture from a desiccant. Sensors are strategically placed throughout the air drying system to measure the state of the air. The air and airflow may be controlled throughout the system based on the sensor measurements.

Herein are disclosed compositions of matter, processes of manufacture and processes of use of solid state admixtures that include an inorganic base and a sulfide selected from the group consisting of an ammonium sulfide, an alkali metal sulfide, an alkali-earth metal sulfide, transition metal sulfide, and a mixture thereof. The composition can include solid state inorganic bases (e.g., calcium hydroxide and sodium sesquicarbonate) and/or gaseous bases (e.g., ammonia) and, optionally, a support material for one or more of the inorganic base and sulfide. The compositions are useful for capturing environmental contaminants, for example, from the flue gas of a coal fired power plant.