KR-102961176-B1 - Carbon Dioxide Reduction System And Method For Ship

KR102961176B1KR 102961176 B1KR102961176 B1KR 102961176B1KR-102961176-B1

Abstract

A carbon dioxide reduction system and method for a ship are disclosed. The carbon dioxide reduction system for a ship according to the present invention comprises: a storage tank provided on the ship for storing LNG; a methanation process unit that receives carbon dioxide emitted from the ship and synthesizes it with hydrogen to convert it into water and methane; and a reliquefaction unit that receives evaporated gas generated from the storage tank and reliquefies it, wherein the methane generated in the methanation process unit can be liquefied in the reliquefaction unit and stored in the storage tank.

Inventors

안지호
김상명
김필근

Assignees

한화오션 주식회사

Dates

Publication Date: 20260507
Application Date: 20210105

Claims (10)

A storage tank installed on a ship for storing LNG; A methanation process unit that receives carbon dioxide emitted from a ship, synthesizes it with hydrogen, and converts it into water and methane; and It includes a reliquefaction unit that receives and reliquefies the evaporated gas generated from the above storage tank, and A carbon dioxide reduction system for a ship characterized by the fact that methane generated in the above-mentioned methanation process unit is liquefied in the above-mentioned re-liquefaction unit and stored in the above-mentioned storage tank, thereby replenishing LNG loss in the storage tank.
In Article 1, A carbon dioxide separation unit that separates carbon dioxide from exhaust gas discharged from the above-mentioned vessel and supplies it to the above-mentioned methanation unit; and A carbon dioxide reduction system for a ship further comprising a hydrogen supply unit that supplies hydrogen generated by the electrolysis of water to the methanation process unit.
In Clause 2, the carbon dioxide separation unit is, A gas filter that receives the above exhaust gas and removes impurities including dust; A carbon dioxide separator that receives exhaust gas filtered from the above gas filter and separates carbon dioxide; and A carbon dioxide reduction system for a ship comprising: a carbon dioxide tank that receives and stores carbon dioxide separated from the carbon dioxide separator and supplies it to the methanation process unit.
In Clause 2, the hydrogen supply unit A water electrolysis cell that electrolyzes water into hydrogen and oxygen; and A hydrogen tank that receives and stores hydrogen generated in the above-mentioned electrolytic cell and supplies it to the above-mentioned methanation process unit, comprising A carbon dioxide reduction system for a ship characterized in that water generated in the above-mentioned methanation process unit is supplied to the above-mentioned water electrolysis tank for hydrogen production.
In any one of paragraphs 2 through 4, The above vessel further includes a renewable energy generation unit that is provided on the vessel and produces electricity using renewable energy including wind and solar power, and A carbon dioxide reduction system for a ship characterized by supplying power for hydrogen generation and carbon dioxide separation from the above-mentioned renewable energy generation unit to the above-mentioned hydrogen supply unit and carbon dioxide separation unit.
In Paragraph 5, A carbon dioxide reduction system for a ship characterized in that the methane generated in the above-mentioned methanation process can be supplied as fuel to gas usage points, including onboard engines.
In a vessel equipped with a reliquefaction unit that receives and reliquefies boil-off gas generated from a storage tank where LNG is stored, Carbon dioxide emitted from ships is supplied to the methanation process unit and synthesized with hydrogen to convert it into water and methane, and A method for reducing carbon dioxide in a ship, characterized by being able to replenish LNG loss in the storage tank by liquefying the methane generated in the above-mentioned methanation process unit in the above-mentioned reliquefaction unit and storing it in the above-mentioned storage tank.
In Article 7, A method for reducing carbon dioxide in a ship, characterized by removing impurities including dust from exhaust gas emitted from the ship and separating carbon dioxide to supply to the methanation process unit.
In Paragraph 8, Hydrogen generated by the electrolysis of water is supplied to the above-mentioned methanation process unit, A method for reducing carbon dioxide in a ship, characterized in that the water generated during methane conversion in the above-mentioned methanation process is circulated as water for hydrogen production.
In Article 9, A method for reducing carbon dioxide in a ship, characterized by generating electricity on board using renewable energy including wind and solar power to supply power for electrolysis for hydrogen production and carbon dioxide separation.

Description

Carbon Dioxide Reduction System and Method for Ship The present invention relates to a carbon dioxide reduction system and method for a ship, and more specifically, to a carbon dioxide reduction system and method for a ship capable of converting carbon dioxide emitted from the ship into methane and processing it by liquefying it in an onboard re-liquefaction unit. As global warming intensifies, efforts to reduce greenhouse gas emissions are being made worldwide. With the 1997 Kyoto Protocol, which contained greenhouse gas reduction obligations for developed countries, set to expire in 2020, the 195 parties participating in the Paris Climate Change Accord—which was adopted at the 21st United Nations Framework Convention on Climate Change held in Paris, France in December 2015 and entered into force in November 2016—are making various efforts to reduce greenhouse gases. Along with these global trends, interest in renewable energy (or renewable energy) such as wind, solar photovoltaic, solar thermal, bioenergy, tidal, and geothermal power is increasing as pollution-free energy that can replace fossil fuels and nuclear power, and various technological developments are underway. In addition, natural gas is an eco-friendly fuel composed mainly of methane that emits almost no environmental pollutants during combustion, and is attracting attention as a complementary energy source to renewable energy. Liquefied Natural Gas (LNG) is obtained by liquefying natural gas by cooling it to approximately -163°C under atmospheric pressure; since its volume is reduced to about 1/600 of its gaseous state, it is highly suitable for long-distance transportation by sea. Therefore, natural gas is mainly stored and transported in the form of liquefied natural gas, which is easy to store and transport. Since the liquefaction point of natural gas is an extremely low temperature of approximately -163°C at atmospheric pressure, LNG storage tanks are generally insulated to maintain the LNG in a liquid state. However, despite being insulated, there are limitations to blocking external heat, and as external heat is continuously transferred to the tank, the LNG continuously evaporates naturally within the tank during transportation, generating Boil-Off Gas (BOG). The continuous generation of boil-off gas in LNG storage tanks causes an increase in the internal pressure. If the internal pressure exceeds the set safety pressure, it can lead to emergency situations such as tank rupture; therefore, the boil-off gas must be vented to the outside of the tank using a safety valve. However, since boil-off gas represents a form of LNG loss and is a significant issue regarding LNG transport efficiency and fuel efficiency, various methods are employed to manage the boil-off gas generated in storage tanks. In order to prevent energy waste and protect storage tanks from overpressure, methods have been developed and applied to ships, such as using evaporated gas at fuel consumption points like ship engines, re-liquefying evaporated gas using a separate refrigeration cycle or the coldness of the evaporated gas itself and recovering it to storage tanks, or using a combination of these two methods. FIG. 1 schematically illustrates a carbon dioxide reduction system for a ship according to one embodiment of the present invention. In order to fully understand the operational advantages of the present invention and the objectives achieved by the implementation of the present invention, reference should be made to the accompanying drawings illustrating preferred embodiments of the present invention and the contents described therein. The structure and operation of a preferred embodiment of the present invention will be described in detail below with reference to the attached drawings. It should be noted that in assigning reference numerals to the components of each drawing, identical components are denoted by the same numeral whenever possible, even if they are shown in different drawings. In the embodiments of the present invention described below, the vessel may be any type of vessel equipped with a storage tank for storing liquefied gas. Representative examples include vessels with self-propulsion capabilities such as LNG carriers, liquid hydrogen carriers, and LNG RVs (Regasification Vessels), as well as offshore structures that do not have propulsion capabilities but float on the sea, such as LNG FPSOs (Floating Production Storage Offloading) and LNG FSRUs (Floating Storage Regasification Units). Furthermore, this embodiment can be applied to all types of liquefied gases that can be transported by liquefying at low temperatures and generate evaporative gas during storage. Such liquefied gases may be liquefied petrochemical gases such as, for example, LNG (Liquefied Natural Gas), LEG (Liquefied Ethane Gas), LPG (Liquefied Petroleum Gas), liquefied ethylene gas, and liquefied propylene gas. However, in the embodiments described below, the application of LNG,