Embodiments described herein provide methods of removing contaminants from a gas, the methods including providing a feed gas to a vertical contactor; flowing the feed gas in a gas flow direction through the vertical contactor; mixing a fresh absorbent makeup with a recycled absorbent to form an absorbent mixture; providing a fresh absorbent feed to the feed gas; flowing the absorbent mixture through the vertical contactor in a liquid flow direction counter to the gas flow direction; recovering a clean gas stream from the vertical contactor; and recovering the recycled absorbent from the vertical contactor.

A system for analyzing a CO.sub.2 concentration of an amine-based absorbing solution includes a measurement apparatus that measures a viscosity of the amine-based absorbing solution and at least one selected from conductivity and ultrasonic propagation velocity of the amine-based absorbing solution, wherein the amine-based absorbing solution absorbs and removes CO.sub.2 from a target gas by gas-liquid contact with the target gas; and a controller that determines the CO.sub.2 concentration of the amine-based absorbing solution from results measured by the measurement apparatus.

Processes for separating carbon dioxide from a gas mixture that comprises CO.sub.2 and N.sub.2 that are based upon formation of gas hydrates, and systems useful for implementing such processes, are disclosed.

Embodiments described herein provide methods of operating a linear contactor for absorbing contaminants from a gas stream. The gas stream flows from a first end to a second end of the linear contactor. Fresh absorbent is provided at the first end of the linear contactor based on the theoretical minimum amount of absorbent needed to remove the contaminants. Absorbent is recycled from the second end to the first end of the linear contactor. Fresh absorbent is provided at the second end based on chemical condition of the recycled absorbent. Apparatus for practicing the method is also described.

An acid gas recovery method includes removing acid gas from a target gas by bringing the target gas containing the acid gas into gas-liquid contact with an absorbent amine solution and causing the absorbent amine solution to absorb the acid gas; regenerating the absorbent amine solution by releasing the acid gas from the absorbent amine solution that has absorbed the acid gas; causing a chelate resin to adsorb iron ions from the absorbent amine solution by causing the absorbent amine solution to pass through the chelate resin; causing a regenerant solution to pass through a chelate resin having iron ions adsorbed thereon; regenerating the chelate resin and obtaining a regenerant solution containing the iron ions and quantitatively measuring the iron ions in the regenerant solution containing the iron ions and calculating a concentration of iron ions in the absorbent amine solution.

Air flows across an air-liquid interface such that liquid desiccant flowing through the interface absorbs water from the air and is thereby diluted to form an output stream. The output stream is circulated through an electrodialytic stack having a central ionic exchange membrane and first and second outer ionic exchange membranes. A redox shuttle loop circulates around the first and second outer ionic exchange membranes. A voltage is applied across the electrodialytic stack, which regenerates the liquid desiccant.

A method for recovering an acidic gas, includes: a step of bringing a gas to be treated that contains an acidic gas into gas-liquid into contact with an amine absorbing solution, allowing the amine absorbing solution to absorb the acidic gas, thereby removing the acidic gas from the gas to be treated; a step of allowing the amine absorbing solution that has absorbed the acidic gas to release the acidic gas, thereby regenerating the amine absorbing solution, and at the same time, recovering the released acidic gas; and an analysis step of calculating concentrations of iron ions and/or heavy metal ions in the amine absorbing solution.

Flue gas generated when fuel is subjected to combustion by a combustor such as a boiler is supplied, and a sulfur oxide is reduced or removed from the supplied flue gas. A desulfurization apparatus 10A includes an absorber 11, a gas introduction unit 13a, an absorbent jetting unit 15, a plurality of water flow oxidation devices 20, an absorbent supplying unit 25, a demister 30, a gas discharging unit 13b, and a control device 40 that varies the number of water flow oxidation devices 20 that jet absorbent 14 and air 21 based on a rate of the sulfur compound in the absorbent 14 within an absorbent storage tank 11A.

A CO.sub.2 recovery system includes: a CO.sub.2 absorber that transports flue gas with CO.sub.2 into contact with a CO.sub.2 absorbent to remove the CO.sub.2 and discharges a rich solution that has absorbed the CO.sub.2; an absorbent regenerator that separates the CO.sub.2 from the rich solution to regenerate the CO.sub.2 absorbent as a lean solution; a gas discharge line where a CO.sub.2 entrained gas from the absorbent regenerator is discharged; a reflux water drum that produces reflux water by separating CO.sub.2 and water from the CO.sub.2 entrained gas; a separation-gas discharge line where the separated CO.sub.2 is discharged; a compressor that compresses the separated CO.sub.2 gas; a condensate water drum that forms compressor condensate water by separating water from the compressed CO.sub.2 gas to form compressor condensate water; and a compressor-condensate water line that supplies the compressor condensate water as in-system or out-of-system supply water.

The invention relates to an integrated set of equipment and a process for treating and refining highly contaminated biogas for the purpose of producing biomethane and to the supply thereof in small volumes of up to 10 m3/h to vehicles, such that the refining unit produces small quantities of biomethane per day to supply motor vehicles operating on the same premises as those where the biogas is produced, such as rural properties and small effluent treatment stations. The unit for refining biogas and supplying biomethane, referred to herein as a biomethane microstation, is an innovative technological concept wherein the microstation comprises the generation of the fuel and the distribution thereof for consumption on the same premises, using a compact biogas refining unit.