CNG Process

The above illustration describes the comparison of the CNG compression process and the LNG liquefaction process. 

For the LNG liquefaction process, the feed gas requires thorough processing including inlet scrubber, amine treatment for acid gas removal, dehydration for water removal, carbons beds for mercury removal, LPG extraction, LPG/C5+ storage, LPG offload, chilling, liquefaction, nitrogen rejection, LNG storage, LNG offload, etc. An LNG liquefaction plant project is highly complex and capital-intensive. A typical LNG project may take five to eight years of permitting, engineering, and construction cycle, including the highly tortuous FERC regulatory process.

In comparison, a CNG Compression facility is a relatively simple facility. The CNG compression station can be constructed within an 18 month period, excluding permitting. Since CNG is compressed and stored at ambient temperature, it avoids boil-off gas generation and has a minimum safety zone (due to negligible vapor dispersion events and thermal radiation). Also, the mercaptan-based odorant may be added to CNG to improve the ease of detection.

Andalusian Energy’s Proposed Plaquemines CNG Compression Facility 

Andalusian Energy Plaquemines CNG Compression Facility

The above illustration shows a 3D model of Andalusian Energy’s proposed Plaquemines CNG compression facility within the footprint of the Port of Plaquemines. As shown in the 3D model, the feed gas is introduced into the plant from the red-colored metering station at the lower right corner. Then the pipeline-quality gas gets further treatment through adsorption dehydration. The dehydrated gas flows into the CNG main compressors in parallel, driven by either electric motors or gas engines (used for blackstart and redundancy in case of electrical failures), to produce the high-pressure CNG product. The CNG will be cooled to counter the compression heat generated when loading into CNG containers at one of the multiple CNG loading manifolds. Fully loaded CNG containers will be stored at the staging yard adjacent to the berth to be lifted by container cranes to an ocean-going containership.