Technical innovations in CNG filling and decompression stations

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Ross Gale, Director of Sales, Universal Vortex Inc
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In today’s competitive global energy market, local distributors of CNG have to be keenly aware of their project and operating costs to remain competitive against LPG, oil, and their direct CNG competitors. There are many conventional ways to make Virtual Pipeline operations more efficient—high-efficiency compressor packages, larger lightweight composite tanks, IT/automation solutions to streamline the supply chain, glycol chillers to compensate for the fill-side heat of compression, and high-efficiency boilers to assist in decompression. Two new ways to increase efficiency and competitiveness is using two Universal Vortex Inc. (USA) products for the CNG tank filling, and decompression processes.
Using a common core technology that capitalizes on a known fluid dynamics phenomenon, UVI has created a solution to both improve CNG tank trailer filling and the downstream decompression process. This technological innovation is making dramatic network efficiency changes in the CNG market globally.

The Core Innovation: Single-Flow Self-Heating Vortex Tube (SHVT): In the SHVT, high pressure gas expands in the units tangential fixed nozzle down to the delivery pressure. In the body, the rotating low-pressure gas undergoes energy division (the vortex phenomenon), forming two currents: cold and hot. The hottest portion of the flow is internally directed to warm up the inlet nozzle (proprietary self-heating), preventing inlet freeze-up. The currents coexist in the SHVT and recombine as they exit a single outlet (proprietary single-flow vortex tube), reflecting only the Joule-Thomson temperature drop.

Vortex Cooling System for CNG (VCS-CNG): Heat of compression negatively impacts the amount of CNG that can be filled into a tank. The solution to the decreased gas volume is an expensive glycol chiller/heat exchanger. On average, this costs approximately US $400,000, and results in significant operating and maintenance expense.
The VCS solution drops the gas pressure from the compressor to meet the low trailer pressure. The vortex tubes deliver gas, chilled by the Joule-Thomson temperature drop between the compressor (250-Bar) and tank, negating the heat of compression. The compact VCS solution costs a fraction of a chiller, has no moving parts, consumes no energy, has no carbon footprint, and provides even more cooling. If the ambient temperature is 38°C, the VCS can deliver gas as low as -47°C! Using the VCS in a 250-Bar system, the maximum temperature outlet to the downstream tank would be less than 13°C.

This solution enables a CNG compression station operator to maximize tank filling. This decreases freight costs, reduces the number of trailers needed, and overall improves the environmental efficiency of a CNG distribution operation.

Vortex Pressure Reduction Station for CNG (VPRS-CNG): The VPRS-CNG system is used globally to increase the efficiency of Virtual Pipeline applications. The solution eliminates gas preheating upstream of the pressure reduction phase, and in most cases eliminates the need for post-heating prior to delivery of pressure regulated gas to the downstream gas consumer. Using an array of self-heating vortex tubes, the VPRS can regulate any conceivable flow from and to any conceivable pressure. The compact system consists of the Vortex array, PLC operated solenoid actuators to control the Vortex array, an ambient air or other heat exchanger to increase the pressure regulated gas temperature, and a buffer/receiver to ensure constant pressure and flow to the downstream customer.

This system, like all of Universal Vortex Inc.'s pressure regulation solutions has no moving parts, consumes no fuel gas, generates no CO2/methane emissions, is not liquid-sensitive, and requires no maintenance, ever! It can also be used in conventional natural gas pressure regulation stations.

Visit Ross Gale and the Universal Vortex Inc team at Stand No. 19-075 at Gastech Exhibition 2017 in Chiba - Tokyo.  

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