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US 9,216,376 B2Granted
Systems and methods for exhaust gas cleaning and/or ballast water treatment
AssigneeKeppel Offshore & Marine Technology Centre Pte Ltd
InventorsMing Liu, Nirmal Raman Gurunthalingam, Prapisala Thepsithar, Wen Sin Chong, Kok Seng Foo
Life of this patent
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Abstract
Embodiments of the present invention relate to a system and method for efficient removal of sulfur oxides (SOx), nitrogen oxides (NOx) and particulate matter (PM) contained in an exhaust gas generated from fuel combustion and efficient treatment of water containing microorganizms (e.g. ballast water).
Claims15
A process for removal of sulphur oxides from exhaust gas comprising the steps of:
- (a) providing a seawater;
- (b) enhancing a SOx adsorption capacity of the seawater to pre-determined levels by controlled dosing with at least one alkaline additive substances introduced from a storage of fresh alkaline additive onboard, and/or an alkaline solution produced from the cathode side of an electrochemical cell and/or their combination thereof to form an alkaline seawater with a pH ranging from 8 to 12;
- and
- (c) contacting an exhaust gas with the alkaline seawater as a scrubbing agent, to produce an exhaust with reduced content of sulphur oxides and a used scrubbing agent;
- wherein a pH of the used scrubbing agent is adjusted to a range of 6.5 to 9 by neutralization with alkaline additive substance, and/or the alkaline water from the cathode side of the electrochemical cell, and dilution with natural sea water;
- and
- wherein the alkaline additive substance used in step (b) is chosen from an alkaline metal compound or an alkaline earth metal compound, where the compound is one of hydroxides, carbonates, bicarbonates, oxides, sulphites and silicates.
4 more elements
A two-step neutralization process for removal of SOx comprising the steps of:
- (a) passing an exhaust gas containing SOx to an open-loop first step neutralization in a first wet scrubber to contact the SOx with a first scrubbing agent;
- (b) adjusting a pH of the used first scrubbing agent with a fresh supply of processed water from an electrochemical cell;
- (c) adjusting an oxidation-reduction potential (ORP) of the used first scrubbing agent, after having adjusted the pH, by aeration;
- (d) after the open-loop first step neutralization, passing the exhaust gas containing SOx remaining from Step (a) to a closed-loop second step neutralization in the upper part of the first wet scrubber or in a second wet scrubber to contact the SOx with a second scrubbing agent;
- (e) ascertaining whether the pH of the used second scrubbing agent exceeds a predetermined pH value;
- (f) circulating the used second scrubbing agent to the closed-loop second step neutralization if the pH of the used second scrubbing agent exceeds the predetermined pH value;
- (g) collecting the used second scrubbing agent in a wastewater storage tank if the pH of the used second scrubbing agent is lower than the predetermined pH value;
- and
- (h) monitoring the salinity of the first scrubbing agent in Step (a) and/or monitoring SOx concentration of the exhaust gas from Step (d) so that an additional operation of the closed-loop second step neutralization is triggered to remove a remaining SOx from the exhaust gas when the salinity of the scrubbing agent is below a first predetermined level and/or when the SOx concentration of the outlet exhaust gas exceeds the second predetermined level.
6 more elements
A closed-loop process for removal of NOx comprising the steps of:
- (a) passing an exhaust gas having NOx through a wet scrubber which includes a scrubbing agent having a high concentration of reducing agent for creating a low oxidation-reduction potential (ORP) condition in the wet scrubber;
- (b) measuring if the used scrubbing agent is capable of creating the low ORP condition for NO2 reduction;
- (c) regenerating the used scrubbing agent in an electrochemical cell if it has insufficient low ORP for NO2 reduction and
- (d) circulating the regenerated scrubbing agent back to the wet scrubber.
1 more element
Dependencies are inferred from the claim text.