Disclosed is a method to discharge lubricant in a system which compresses boil-off gas (BOG) by a compressor, cools the compressed BOG through heat exchange with the BOG before compression in a heat exchanger, and decompresses a fluid, which is cooled by the heat exchange, by a decompressor to reliquefy the BOG. According to the present invention, when one or more conditions among the following conditions are satisfied, the method to discharge lubricant determines that it is a time point to discharge condensed or solidified lubricant. A first condition is that the compressor comprises at least one a lubrication type cylinder and a state, in which a temperature difference (hereinafter, referred to as a temperature difference of a low temperature flow) between a temperature at a front end of the heat exchanger of the BOG used as coolant in the heat exchanger and a temperature of the BOG cooled by the heat exchanger after being compressed by the compressor is equal to or greater than a first set value, is continued for a predetermined period or longer. A second condition is that a state, in which a temperature difference (hereinafter, referred to as a temperature difference of a high temperature flow) between a temperature of the BOG used as the coolant in the heat exchanger and a temperature of the BOG sent to the heat exchanger after being compressed by the compressor is equal to or greater than the first set value, is continued for a predetermined period or longer. A third condition is that a state, in which a pressure difference (hereinafter, referred to as a pressure difference of a high temperature flow path) between a pressure at the front end of the heat exchanger of the BOG sent to the heat exchanger after being compressed by the compressor and a pressure at a rear end of the heat exchanger of the bot cooled by the heat exchanger is equal to or greater than a second set value, is continued for a predetermined period or longer.

    증발가스를 압축기에 의해 압축시키고, 압축된 증발가스를 압축되기 전의 증발가스와 열교환기에서 열교환시켜 냉각시키고, 열교환시켜 냉각시킨 유체를 감압장치에 의해 감압시켜, 증발가스를 재액화시키는 시스템 내의 윤활유를 배출시키는 방법이 개시된다.상기 윤활유 배출 방법에 의하면, 상기 압축기는 급유식 실린더를 적어도 한 개 포함하고, 상기 열교환기에서 냉매로 사용되는 증발가스의 상기 열교환기 전단에서의 온도와, 상기 압축기에 의해 압축된 후 상기 열교환기에 의해 냉각된 증발가스의 온도 차이(이하, '저온 흐름의 온도 차이'라고 한다.)가 제1 설정치 이상인 상태가 일정시간 이상 지속되는 조건; 상기 열교환기에서 냉매로 사용된 증발가스의 온도와, 상기 압축기에 의해 압축된 후 상기 열교환기로 보내지는 증발가스의 온도 차이(이하, '고온 흐름의 온도 차이'라고 한다.)가 제1 설정치 이상인 상태가 일정시간 이상 지속되는 조건; 및 상기 압축기에 의해 압축된 후 상기 열교환기로 보내지는 증발가스의 상기 열교환기 전단에서의 압력과, 상기 열교환기에 의해 냉각된 증발가스의 상기 열교환기 후단에서의 압력 차이(이하, '고온 유로의 압력 차이'라고 한다.)가 제2 설정치 이상인 상태가 일정시간 이상 지속되는 조건; 중 하나 이상을 만족하면, ‘응축 또는 응고된 윤활유를 배출시켜야 할 시점’이라고 판단한다.


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    Title :

    Boil-Off Gas Reliquefaction System and Method of Discharging Lubrication Oil in the Same


    Additional title:

    증발가스 재액화 시스템 및 증발가스 재액화 시스템 내의 윤활유 배출 방법


    Contributors:

    Publication date :

    2018-10-16


    Type of media :

    Patent


    Type of material :

    Electronic Resource


    Language :

    Korean


    Classification :

    IPC:    B63B Schiffe oder sonstige Wasserfahrzeuge , SHIPS OR OTHER WATERBORNE VESSELS / B63H Schiffsantrieb oder Steuerung der Schiffe , MARINE PROPULSION OR STEERING / F17C Behälter zum Aufnehmen oder Speichern verdichteter, verflüssigter oder verfestigter Gase , VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES



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