Amount-of-seawater control device for scrubber, amount-of-seawater control method for scrubber, and amount-of-alkali control device

An amount-of-seawater control method for a scrubber which controls an amount of seawater supplied to a scrubber that cleans sulfur oxide contained in exhaust gas by bringing the sulfur oxide into contact with seawater, the amount-of-seawater control method comprising:

• calculating a minimum amount of seawater necessary for an absorption reaction of the sulfur oxide by the seawater based on an engine output, a sulfur content of fuel oil, an alkalinity of the seawater set in accordance with a location of waters through which a vehicle including the scrubber travels, and a limit value for a concentration of sulfur oxides in the exhaust gas, the limit value corresponding to the location of the waters traveled by the vehicle;
• calculating a corrected amount of seawater to be applied to the minimum amount of seawater based on a differential between the concentration of the sulfur oxide contained in the exhaust gas discharged into the atmosphere from the scrubber and a set value for the concentration of sulfur oxides determined from the limit value;
• correcting the minimum amount of seawater by the corrected amount of seawater to generate a set amount of seawater value;
• and
• controlling a pump such that the set value, corresponding to the minimum amount of seawater corrected by the corrected amount of seawater, is supplied to the scrubber.

An amount-of-alkali control device for a scrubber for controlling an amount of alkali injected into seawater supplied to a scrubber that cleans sulfur oxide contained in exhaust gas by bringing the sulfur oxide into contact with seawater, the amount-of-alkali control device comprising:

• a minimum-amount-of-seawater converter configured to calculate a minimum amount of seawater necessary for an absorption reaction of the sulfur oxide by the seawater based on an engine output, a sulfur content of fuel oil, an alkalinity of the seawater set in accordance with waters traveled by a vehicle including the scrubber, and a limit value for a concentration of sulfur oxides in the exhaust gas, the limit value corresponding to the waters traveled by the vehicle;
• an amount-of-seawater correction converter configured to calculate a corrected amount of seawater to be applied to the minimum amount of seawater on the basis of a differential between a concentration of the sulfur oxide contained in the exhaust gas discharged into the atmosphere from the scrubber and a set value for the concentration of sulfur oxides determined from the limit value;
• a pump control device configured to control a pump to supply a set amount of seawater, corresponding to the minimum amount of seawater corrected by the corrected amount of seawater, to the scrubber;
• an amount-of-alkali calculator configured to calculate an alkali injection amount from an alkali content contained in the set amount of seawater;
• and
• an alkali pump control device configured to control an alkali pump to inject into the seawater an alkali agent corresponding to the alkali injection amount prior to supplying the seawater to the scrubber.