Careers Power Plant SCR Upgrades That Deliver Lasting Performance
IGS helped APS Four Corners recover MW capacity, extend catalyst life, and eliminate back pressure derates.
The APS Four Corners Power Station, a 1,540 MW coal-fired facility located near Fruitland, New Mexico, faced a serious challenge: after just six years of SCR system operation, Units 4 and 5 were experiencing severe back pressure, fly ash buildup, shortened catalyst life, and safety risks.
These issues threatened compliance with NOx emissions standards, derated unit performance, and increased maintenance burden – particularly during high-load summer months.
Integrated Global Services (IGS) was brought in to identify the root causes and engineer a long-term solution. Their scope included the redesign and replacement of LPA screen systems and SCR air cannon cleaning technology – two key elements that had degraded significantly over time and could no longer meet operational demands.
Ensure Consistent Output – Avoid Forced Outages
Back Pressure From Ash Piling Was Forcing Derates And Threatening Catalyst Integrity
IGS’s analysis revealed that the existing LPA screens were 50% blocked by accumulated ash. The associated cleaning system, initially supplied by another vendor, had failed, allowing Large Particle Ash (LPA) to enter the SCR and accelerate erosion. Air cannon systems had also deteriorated due to internal corrosion and poor pressure tolerance, with some cannons detaching from the SCR walls entirely. These failures created performance bottlenecks, increased maintenance requirements, and introduced serious safety risks.
Work Smarter And Safer
IGS Delivered A Comprehensive, Resilient Solution Engineered For High-Stress Environments
To address these issues, IGS installed new LPA screen panels coated with a durable, two-stage erosion-resistant finish. They replaced the outdated rapper system with high-performance air cannons designed for positive pressure environments and equipped with monitoring capabilities. The advanced “Multiplier” system dramatically reduced the number of ASME pressure vessels required per unit and moved critical components away from the corrosive gas stream, minimizing future maintenance demands.
Reduce Outage Frequency Through Long-Term Protection
Within 100 Days, Back Pressure Dropped By 30–60% And Catalyst Life Was Restored
Following the upgrades, Unit 5’s system differential pressure dropped from 12–13 in-H₂O to 9.5–10.5 in-H₂O at 675 MW. Catalyst life was extended by two years, reducing the need for premature changeouts. Derates caused by back pressure were eliminated, and ash buildup was dramatically reduced. Engineers confirmed that the system was “working as intended,” with performance metrics exceeding original expectations.
“This wasn’t just about cleaning screens—it was about restoring confidence in the SCR system’s ability to perform under pressure. Our teams designed a future-ready solution that gave APS the performance certainty they needed.”
– IGS Business Development Lead
Boost Profitability Without Major Capex
$2.2M ROI Per Unit Achieved Through Catalyst Extension And Downtime Avoidance
The total project cost—approximately $3M per unit—was quickly justified by eliminating two catalyst layer changeouts and restoring full unit output. Financial benefits also included reduced fan energy use and avoided maintenance costs. With both Units 4 and 5 now optimized for long-term performance, APS can expect stable SCR operation through the plant’s projected end-of-life in 2031.
Proven 30–60% dP reduction, catalyst life extended by two years, and full-load output restored.
Download the full case study to see how APS Four Corners achieved measurable SCR efficiency.
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