OPTIMAL NATURAL GAS LIQUID (NGL) EXTRACTION WITH A MODULAR MINDSET
Maximizing Liquids Recovery for Maximum Project Profitability
Enerflex cryogenic systems are engineered for efficient NGL recovery from natural gas streams ranging from 15 MMSCFD to more than 300 MMSCFD. Highly reliable, industry-proven designs, such gas subcooled process (GSP), recycle split vapor (RSV), overhead recycle (OHR), and single column overhead recycle (SCORE), are used to meet clients’ varying requirements.
With the October 13, 2022, acquisition of Exterran by Enerflex, clients can expect that we will continue to offer the same outstanding Exterran products they know and trust, while pairing them with Enerflex’s renowned level of service and support. Exterran’s proven teams will continue to deliver Exterran Cryogenic solutions to customers worldwide.
Ultra-Low Temperatures from Ultra-High Recovery
Cryogenic processing cools liquids-rich natural gas to sub-zero temperatures to extract liquids — such as ethane (C2) and propane (C3) — prior to injecting lean residue gas into the sales pipeline. Maximizing recovery of these valuable hydrocarbon liquids increases revenue for natural gas producers.
Enerflex in Action
- DJ Basin, Denver, Colorado, USA
Two Exterran Cryogenic Custom 300 MMSCFD Multi-Process Cryogenic Plants
Enerflex engineered, designed, manufactured, and commissioned two custom-built multi-process Exterran Cryogenic 300 MMSCFD cryogenic plants as part of a four-site long-term project in Colorado’s DJ Basin.
This was a stick-built semi-modular solution that included two (2) cryogenic NGL recovery processing trains — which can operate in a range of modes depending on desired recovery: GSP (Gas Subcooled Process), SCORE (Single Column Overhead Recovery), and SRC (Supplemental rectification with compression). Each train has two (2) 600 GPM amine units treating up to 150 MMSCFD of inlet gas to remove CO2, one (1) molecular sieve dehydration system to remove up to 112 lbs of water, H2S removal beds, a supplemental refrigeration system with three (3) 3,000 HP electric-driven rotary screw refrigeration compressors, and two (2) 12,000 HP electric-driven centrifugal residue compressors. Additionally, there is a common NGL system that consists of numerous surge vessels and NGL pipeline pumps which allow the product NGLs to flow to a Y-grade pipeline for transport to the Gulf Coast for further product fractionation.
Due to uncertainty in future ethane markets and limited NGL pipeline takeaway at the time of construction, the focus of the design of the plant was to maximize flexibility in operating modes, with a priority for deep propane recovery during both ethane recovery and ethane rejection modes. Additionally, the customer sought to minimize overall compression power (both refrigeration and residue) to reduce long-term operating costs.
Located in the center of the customer’s asset base, the plant can operate in both GSP rejection and recovery modes, and SCORE rejection mode while maintaining ultra-high propane recovery with minimal residue horsepower required. Additionally, there are provisions and connections to allow operation in SRC operating mode if higher ethane and propane recovery are desired simultaneously.
Given the customer’s requirements for a modular design for quick delivery and reduced construction costs, the application of patented processes to handle specific recovery needs, and pre-engineered design experience with dozens of proven deep cut projects in a variety of sizes, they chose the Exterran Cryogenic solution — known and trusted in the market for over 50 years.
This custom design was the first of its kind to allow all three process modes to optimize recoveries for several possible commodity price scenarios. GSP and SCORE technologies pair well together. While SCORE maintains high propane recoveries (99+%) throughout low ethane recovery modes (0-30%), GSP can operate across the entire range of ethane recoveries (~0% – 90%). In addition, the SRC technology could be employed if ultra-high C2 recoveries (~99+%) are ever desired. SRC can also achieve much higher C3 recoveries compared to GSP during partial recovery modes (~30% – 90% C2 recoveries).
Since startup, the facility has been debottlenecked to safely operate above the original design nameplate at near design recoveries to handle peaks in field production.
This project was completed on time, within budget, and with zero safety recorded incidents. Enerflex delivered on all levels of design and production – with higher than designed recoveries. As a result of this great success in execution, additional work was awarded to Enerflex across all four sites.
- Powder River Basin, Douglas, Wyoming, USA
200 MMSCFD Integrated Turnkey (ITK) Cryogenic Plant
Enerflex engineered, designed, procured, manufactured, constructed, commissioned, and started-up a 200 MMSCFD cryogenic plant integrated with a 10,000 BBL/D stabilizer — which more than doubles the customer’s processing capacity at the heart of its pipeline network.
A two-tower stabilizer design was selected to minimize the overhead compression requirements and enhance operability. The plant specification included stripper, stabilizer, fractionator, and absorber towers; three molecular sieve beds; a 5,000 HP CAT 3616 A4 two-stage with Ariel KBZ/4 residue gas compressor package, capable of moving 50 MMSCFD at 1,440 psig; and a 3,500 barrel harp-style slug catcher. Onsite storage is provided for 630,000 gallons of NGL and 15,000 barrels of condensate.
The customer requested a custom solution that maximized propane recovery, instead of typical ethane, though future expansion into ethane is feasible. By focusing on higher value propane at a 94% recovery rate, this facility avoids the expense of a refrigeration system and saves energy. Enerflex’s flexible design offers the ability to recover different reid vapor pressure (RVP) products to maximize both condensate value and NGL value depending on the plant feed composition and market conditions.
Enerflex provided a one-stop solution to engineer and procure the total balance of plant design necessary to integrate two processing units, as well as manage the construction and commissioning phases of the plant. Enerflex’s site team oversaw a horizontal contracting strategy that peaked with over 400 people.