Ship Cargo Loading Pipe Pressure Control Bypass
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Solution Overview
Problem
The existing methods for loading liquid cargo, such as LNG and crude oil, into ships result in evaporation due to differential pressure, leading to increased loading time and potential malfunctions when pressure regulators fail, causing environmental pollution and additional processing costs.
Innovation Solution
A system that includes a pressure regulator and a bypass pipe with a bypass valve at the lower end of the loading pipe, allowing liquid cargo to be loaded through both pipes to maintain pressure above the vapor pressure of the cargo, ensuring efficient loading and continuous operation even if the pressure regulator malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure regulator is provided to the lower end of the loading pipe to maintain pressure above vapor pressure, then evaporation of liquid cargo is prevented, but loading time increases due to differential pressure
Solution Approach 1:
The loading system is divided into two separate paths: a loading pipe equipped with a pressure regulator to prevent evaporation, and a bypass pipe for rapid cargo transfer. This segmentation allows each path to serve its specific function - the loading pipe maintains pressure control while the bypass pipe enables fast loading, thereby resolving the contradiction between evaporation prevention and loading speed.
2Reliability
If a pressure regulator is provided to maintain pressure above vapor pressure, then boil-off gas generation is reduced, but the system becomes vulnerable to malfunction
Solution Approach 1:
A bypass pipe is installed in advance as a backup path that can be activated if the pressure regulator malfunctions. This beforehand cushioning ensures that even if the primary pressure control system fails, the cargo loading can continue through the bypass pipe, maintaining system operability and reducing vulnerability to regulator failures.
3Productivity
If the pressure regulator is fully opened to increase loading speed, then differential pressure is reduced, but pressure may drop below vapor pressure causing evaporation
Solution Approach 1:
The system segments the cargo loading function into two distinct pathways: the loading pipe with pressure regulator for controlled pressure maintenance, and the bypass pipe for high-speed loading. This allows the bypass pipe to be opened fully for maximum loading speed without compromising pressure control, as the loading pipe continues to maintain pressure above vapor pressure levels.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This system reduces boil-off gas generation, increases loading speed by up to 20%, and allows uninterrupted cargo loading, minimizing environmental impact and operational costs.
Implementation Method 1
maintain an inner pressure of the pipe at a level above a vapor pressure of liquid cargo
Implementation Method 2
a sensing unit placed apart from the pressure regulator; wherein a degree of opening of the pressure regulator is controlled based on information sensed by the sensing unit
Implementation Method 3
a loading pipe extending downwards from the feed pipe toward a bottom of the storage tank
Implementation Method 4
the inner pressure of an upper end of a loading pipe extending in a vertical direction of a storage tank becomes lower than vapor pressure of liquid cargo due to water head differential within the pipe
Data Source
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AI summary
Disclosed are a system and a method for preventing liquid cargo in a ship from evaporating, which can prevent or reduce generation of evaporated gas when liquid cargo such as LNG, LPG, crude oil, etc., is loaded in a storage tank in a ship, by adjusting the pressure inside a load pipe when the liquid cargo is loaded. The system for preventing liquid cargo in a ship from evaporating, which prevents evaporated gas of the liquid cargo from being generated when the liquid cargo is loaded in the storage tank capable of storing liquid cargo, comprises: a pressure control means installed in a pipe for loading the liquid cargo in the storage tank; a pressure transmitter which is installed on the upper stream side in the pipe above the pressure control means, measures the inner pressure of the pipe, controls an opening degree of the pressure control means on the basis of the measured value; and a bypass pipe which branches off from the pipe such that the liquid cargo is loaded in the storage tank by bypassing the pressure control means.