System and method for recovering ammonia from a gas stream

Abstract

A system for recovering ammonia from a gas stream is provided. The system includes a regenerator and a carbon dioxide wash station.

Description

TECHNICAL FIELD[0001]Embodiments of the invention relate generally to technologies for recovering ammonia from a gas stream.BACKGROUND[0002]In the combustion of a fuel, such as coal, oil, peat, waste, etc. in a combustion plant, such as those associated with boiler systems for providing steam to a power plant, a hot process (or flue gas) is generated. Such a flue gas will contain, among other things, carbon dioxide (CO2), sulfur dioxide (SO2), hydrogen disulfide (H2S2), and / or carbonyl sulfides (OCS). A variety of methods and technologies exist in order to remove the pollutants from the flue gases. One method for the removal of carbon dioxide from a post-combustion flue gas is the Chilled Ammonia Process (CAP).[0003]With this the absorption of carbon dioxide from the flue gas is achieved by contacting a chilled ammonia ionic solution (or slurry) with the flue gas. For example, the flue gas is brought into countercurrent contact with an absorption solution, for example, a liquid ammo...

AI Technical Summary

Benefits of technology

The patent describes a system and method for recovering ammonia from gas streams by using a regenerator and a carbon dioxide wash station. The system heats a solution containing carbon dioxide and ammonia to create a gas stream with residual ammonia. The gas stream is then contacted with an acidic solution to produce an ammonia-rich solution and a carbon dioxide-rich gas stream. The technical effect of this invention is the efficient and effective recovery of ammonia from gas streams.

Problems solved by technology

One of the highest cost penalties of the absorption-capture type systems is the regenerator.

The heat and energy required to release the contaminants from the solution heavily burdens the rest of the plant.

In some cases, steam can be used for heating from other parts of the power plant, but then that is at a cost to the plants' electric output and production.

While this may reduce the need for steam, this further taxes the plant by requiring the additional energy to run the reboiler.

Thus, heating an ammonia-based solution to facilitate release of the CO2 is often an expensive process.

While these benefits are useful, they come at the cost of requiring high-pressure steam and increasing the overall electric demand, which penalizes the power plant output.

To meet these needs by reducing / lowering the pressure of CO2-rich gas stream (as produced by a regenerator operating at a high internal pressure) is typically an expensive process.

Furthermore, when operating the regenerator at a lower pressure, the ammonia slip increases substantially, thus increasing the operating costs and ultimately not reducing steam consumption because of the increased duty of the stripper.

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