| 主权项 |
1. A method for recovering boil-off gas from a head space of a liquid storage tank having a fluid contained therein, the method comprising the steps of:
(a) measuring a condition selected from the group consisting of outside temperature, temperature within the liquid storage tank, pressure within the liquid storage tank, liquid level within the liquid storage tank, heat absorption by the liquid storage tank, and combinations thereof; (b) flowing boil-off gas from the liquid storage tank to a heat exchanger by opening a valve, wherein the valve is configured to adjust the flow rate of the boil-off gas to the heat exchanger based on the condition measured in step (a); (c) creating a vacuum within the heat exchanger by cooling and condensing the boil-off gas in the heat exchanger by using cold energy from a flow of nitrogen to form a cooled fluid, wherein the heat exchanger is in fluid communication with an outlet of a liquid nitrogen storage tank, such that the heat exchanger is configured to receive a flow of nitrogen from the liquid nitrogen storage tank; and (d) introducing the cooled fluid to the liquid storage tank, thereby reducing the temperature within the liquid storage tank, wherein the flow rate of the boil-off gas pumped from the liquid storage tank to the heat exchanger and/or the flow rate of the nitrogen from the liquid nitrogen storage tank is adjusted, such that during the cooling step (c), BTUs of heat are removed from the boil-off gas faster than BTUs are gained by the liquid storage tank, wherein the heat exchanger is disposed at a point above the top of the liquid storage tank, such that the cooled fluid has a static head pressure exceeding that of the fluid within the liquid storage tank. |
