System and method for pressurizing LNG cylinders for vehicles using CNG

Abstract

The invention provides a system and method for pressurizing a vehicle LNG gas cylinder with CNG. A CNG storage tank is additionally arranged on the basis of the LNG gas cylinder, and compressed high-pressure natural gas in the CNG storage tank is adopted for filling gas and increasing pressure into the LNG gas cylinder after pressure reduction. Compared with a traditional LNG air-temperature-type self-pressurization mode, the influence on the environment temperature by a pressurization system is eliminated, and the pressurization speed of the LNG gas cylinder is increased. Meanwhile, the condition that pressurization cannot be achieved when the LNG gas cylinder lacks of liquid is avoided, great potential risks existing in a traditional exposed self-pressurization finned coil pipe are also eliminated, and heat leakage points of the LNG gas cylinder are reduced. A system pressurizing loop pressurizes a CNG gas cylinder in the way that a CNG overflowing valve, a CNG pressurization stop valve, a pressure reducer, a CNG pressure increasing and regulating valve and a gas return stop valve sequentially communicate with a gas-phase space of the LNG gas cylinder. The CNG sequentially communicates with the CNG gas cylinder for supplementing and adding gas through a gas source, a CNG adding opening, a CNG inlet ball valve and a CNG inlet check valve.

Description

technical field [0001] The invention relates to a system for using CNG to pressurize LNG cylinders for vehicles, belonging to the field of natural gas fuel supply systems for vehicles. Background technique [0002] In recent years, LNG vehicles have been widely used in the automotive industry due to their good environmental protection, high safety performance, low price, high storage density and long driving range. However, after the LNG vehicle is refilled at the refueling station that has just unloaded the liquid, or after it has been placed in a low-temperature environment for a long time, the pressure of the gas cylinder is often very low, which cannot meet the normal working requirements of the engine. At this time, users expect to be able to quickly Pressurize the gas cylinder; when the LNG vehicle is supplying gas to the engine, the gas supply pressure in the vehicle LNG cylinder will also drop slowly. At this time, the LNG cylinder should also be pressurized to make ...

AI Technical Summary

Problems solved by technology

However, there are many problems in this supercharging method: (1) the supercharging speed is slow, and the dependence on the external environment is quite large; (2) when the liquid volume of the gas cylinder is less than 30%, it often occurs The liquid level is too low and the pressurization is impossible; (3) the exposed finned tubes cause a major safety hazard in the traditional vehicle LNG system; (4) the self-pressurized finned tubes are also an important leakage hotspot

Images