Carl Wise, Senior Business Development Manager, Thompson Industrial Services
HRSG cleaning is an effective way to restore lost performance because it reduces the back-pressure on the gas turbine, thereby increasing the net power output or reducing the cost of fuel per megawatt generated.
Every additional half-inch (water column) of pressure drop through a typical F-class HRSG reduces the bottom line by about $100,000 per annum, depending on the price of fuel. An effective cleaning could be expected to regain at least 3-6 inches of pressure drop.
Common off-line cleaning methods such as dry ice blasting or vibration require scaffolding or sky climbers that are expensive and time consuming and may be only marginally effective due to limited penetration or cleaning influence in the densely packed finned tube bundles. Another pressure-wave cleaning measure utilizes the repeated insertion of bags containing combustible gas that are dangled at various elevations and detonated near the heat transfer surface, but may be expensive, time consuming and repeatedly cause superfluous impact to surfaces, equipment and structural components that are virtually nonessential to improving efficiency or enhancing the objective for cleaning.
A new solution based on 14 years of proven technology
When utilized routinely for 24/7/365 performance, the off-line application of pulse-detonation cleaning technology, which has been proven and substantiated over the past 14 years, has recently demonstrated dramatic improvements in off-line cleaning results of severely fouled, tightly packed finned tube harps in HRSGs, when compared to existing methods. As an example, one recent application to a Nooter/ Eriksen unit resulted in a 4-inch combustion turbine decrease with a net payback of 41 days, based on full load performance.
Off-line pulse-detonation, or "shockwave," cleaning technology provides several advantages over other cleaning methods:
- Effective cleaning energy: Over the past 14 years, shockwave cleaning technology has proven to provide penetrating and all-encompassing cleaning energy that can extend far into the tube bank and effectively dislodge deep and impacted deposits from heat transfer surfaces.
- Frequently reduced cleaning time, shorter outages: The technology employs an automated cleaning rig that can navigate quickly across the heat transfer surface without the need for scaffolding or man-baskets, significantly reducing overall cleaning time compared to other methods.
- Extremely safe for personnel and the surrounding structure: The shockwave cleaning energy is remotely generated safely within the specially engineered combustion tube and then exhausted directly and focused only at the heat transfer surface so the surrounding structure is not exposed to indiscriminate and potentially harmful explosions, while all personnel are located securely outside the structure throughout the cleaning process.
The negative effects are undeniable: Fouling on the gas side of HRSG tubes compromises plant performance. But you can restore lost performance through innovative HRSG cleaning that reduces back-pressure on the gas turbine, increasing net power output. Through this method, combined-cycle facilities are regaining 3-6 inches of pressure drop and reducing their bottom line by $600,000 or more annually. This highly safe and effective cleaning technology provides penetrating, all-encompassing cleaning energy that dislodges deeply impacted deposits from heat transfer surfaces far into the tube bank. When it comes to safety considerations of various HRSG cleaning techniques, automated methods like off-line pulse-detonation cleaning technology reduce hazard exposure, cleaning time and outage duration.
For more information, visit www.thompsonindustrialservices.com or call (800) 849-8040.
