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METHOD AND PROCESS FOR FLUE GAS DESULFURIZATION WASTE WATER TREATMENT

IP.com Disclosure Number: IPCOM000249978D
Publication Date: 2017-May-11
Document File: 4 page(s) / 113K

Publishing Venue

The IP.com Prior Art Database

Abstract

The invention discloses systems and methods for flue gas desulfurization (FGD) waste water treatment using selective ion filters. This invention is novel and uses monovalent selective electrodialysis (MSED) to selectively remove Cl from FGD wastewater. The system includes a sorption spray tower where flue gas meets water and limestone slurry spray to react with sulfurous constituents in the gas. After simple pretreatment to remove suspended solids the spent slurry overflow waste water is fed into a battery of monovalent selective electrodialysis cells (MSED) to selectively remove NaCl. The MSED system includes several modules of cation and anion selective membranes arranged in tandem. The MSED dilute steam is recycled back as FGD tower makeup water, thereby achieving zero external water discharge from the plant. The removed NaCl is concentrated to recover pure NaCl. The process is simple and provides significant cost advantage over current approaches.

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METHOD AND PROCESS FOR FLUE GAS DESULFURIZATION WASTE WATER TREATMENT

BACKGROUND

The invention relates generally to water treatment and in particular to systems and methods for flue gas desulfurization (FGD) waste water treatment. FGD waste water is not allowed to be discharged without treatment as it typically contains high content of Ca, Mg and Na ions beyond acceptable discharge limits. Nowadays, flue gas from the power plants must be cleaned before discharge into the environment. Typically, wet flue gas desulfurization (FGD) is used for DeSOx, and FGD wastewater is generated during the process. FGD wastewater is known to be extremely tough to treat, and there is an urgent need to find environmentally friendly ways to treat this wastewater while making economic sense. Current practice is using pretreatment and thermal based process to treat FGD wastewater, and the chemical consumption is huge due to high Ca and Mg concentration in the wastewater, and the energy consumption and capital cost is high due to thermal based process. Meanwhile current existing processes are mainly focused on the wastewater treatment, while the reason to discharge the effluent from FGD tower is to maintain the Cl concentration below 20,000 ppm to avoid corrosion problem.

BRIEF DESCRIPTION OF DRAWINGS

The invention discloses system and method flue gas desulfurization waste water treatment in which:

FIG. 1 illustrates the system and process for treatment of flue gas desulfurization waste water using MSED.

FIG. 2 illustrates process for chloride removal from FGD waste water using monovalent selective electrodialysis.

DETAILED DESCRIPTION

The invention discloses systems and methods for flue gas desulfurization waste water treatment using selective ion filters. This invention is novel and uses monovalent selective electrodialysis (MSED) to selectively remove Cl from FGD wastewater after simple pretreatment, and the treated wastewater is recycled back as the FGD makeup water without any water discharge, as illustrated with reference to FIG. 1 and FIG. 2.

As shown in FIG. 1, the system includes a sorption spray tower where flue gas meets water and limestone slurry spray to react with sulfurous constituents in the gas. After simple pretreatment to remove suspended solids the...