Economic and efficient dilution of natural gas using Chart's bulk storage solution

Company:

This major electric and gas utility company includes businesses of regulated electric and natural gas utility operations and other non-regulated energy-related businesses. Two sites are located in the Southeastern part of the U.S.

Design Challenges:

• Dilute incoming natural gas feed stock by 2.5% with nitrogen to control BTU quality
• Design and verify LN₂ for 2.5% of volume
• Four days of LN₂ on-site storage at 24 hours/day operation
• Design surge capacity in pipe downstream of vaporizers to minimize on/off cycling of pumps

Solution:

Install three 30,000 gallon storage vessels for a total of 90,000 gallons of LN₂ storage at Site A and four 15,000 gallon storage vessels for a total of 60,000 gallons of LN₂ storage at Site B.*

The pump skid is specifically engineered to provide optimum performance with the Chart Siphon 100^® Bulk Storage Tank design. The skid is self-contained, pre-assembled, and tested to meet specification requirements. The pump skid takes low pressure liquid nitrogen from the Siphon 100 tank, increases the pressure, and force-feeds the vaporizers and downstream piping to the gas injector system.

*Each site to use one pump skid, four ambient vaporizers, and one nitrogen gas injector.

Design basis specific to Site A includes:

• Requirements to dilute the LNG require nitrogen injection at the rate of 82,000 SCFH, equating to 16.4 GPM pumping and on-site storage of 93,000 gallons of LN₂ to meet the 4 days at 24 hours/day operation.
• 10” pipe tie-in
• GE PLC control system
• Additional flow meter required downstream of injector (use as a check meter) and must be compliant with applicable AGA custody transfer standards.

Design basis specific to Site B includes:

• Requirements to dilute the LNG require nitrogen injection at the rate of 55,000 SCFH, equating to 10.8 GPM pumping and on-site storage of 60,000 gallons of LN₂ to meet the 4 days at 24 hours/day operation.
• 8” pipe tie-in
• Bristol control system
• Meter is an orifice style, must be compliant with applicable AGA custody transfer standards
• Instrument air circuit required at 100 – 115 psi

Outcome:

Successful economic dilution of incoming natural gas feed stock by 2.5% with nitrogen gas from LN₂ storage.