Once-Through Steam Generators
OTSGs are used in the Canadian oil sands to generate the steam utilized to heat heavy oil deposits, or bitumen, in steam-assisted gravity drainage (“SAGD”) recovery projects. SAGD involves drilling one horizontal well to inject steam, generated by an OTSG, into a reservoir in order to heat and melt the bitumen. A second horizontal well is drilled at a lower depth in order to extract the less viscous crude that is created from the melted bitumen. OTSGs are critical to the SAGD process as they are the primary technology used for steam generation. The “steaming” process is the first step in production and generally lasts about nine months, after which production can commence. SAGD is expected to be the dominant production technology over surface mining oil sands recovery, as it generally produces favorable economics, higher recovery rates and has less environmental impact.
Once-Through Steam Generators for both SAGD and CSS applications, ranging in the size from 50 MM BTU/hr to over 250 MM BTU/hr. These are traditional horizontal cylindrical radiant sections with water circuiting designs which enhance the unit performance.
Typical OTSG Options
- Flue Gas Recirculation – for NOx emission reduction
- Heated Skid Enclosures – for improved operation & maintenance environment
- On-line Steam Quality Measurement and pass balancing
- Forced Circulation Designs for ASME Quality Water
- Self-contained Air Pre-Heater Systems
- Integral Steam / Water Annex Buildings
- Cr-Moly Pipe for improved erosion characteristics
- 6 Pass 3-inch Designs
- 4 Pass 4-inch Designs
Each unit is custom designed to client-specific project requirements. This includes thermal design, 3D modeling of all components, pipe stress analysis, instrumentation and controls design to provide a reliable product.