Forced Circulation Steam Generator Water-Cooled Walls
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Solution Overview
Problem
Existing steam generators for heavy oil recovery processes, such as once through steam generators and drum boilers, suffer from high maintenance requirements, thermal inefficiencies, water wastage, limited steam capacity, and high capital and operating costs, as well as challenges in handling water quality upsets.
Innovation Solution
A forced circulation steam generator design that uses a furnace with water-cooled walls and an evaporator unit to produce steam from treated produced water, achieving high quality steam injection with reduced blowdown and maintenance needs, by pumping treated water through the water-cooled walls and evaporator unit to create a water-steam mixture that is then separated to produce 95% or more quality steam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If once through steam generators are used, then steam generation capability is provided, but high blowdown occurs causing thermal inefficiencies and water wastage
Solution Approach 1:
The system uses a steam drum to separate steam from water, allowing the water to be recirculated back through the evaporator. This self-recirculating mechanism eliminates the need for continuous blowdown, reducing both water wastage and thermal energy loss while maintaining steam generation capability
Solution Approach 2:
Instead of discarding the water through blowdown as in once-through systems, the patent recovers the water by separating it from the steam in the steam drum and returning it to the evaporator for continued use, thereby eliminating water wastage and associated thermal inefficiencies
2Reliability
If once through steam generators with refractory/insulated furnaces are used, then steam generation is achieved, but substantial maintenance is required
Solution Approach 1:
The patent replaces the refractory/insulated furnace system with a water-cooled furnace wall system. This substitution eliminates the need for refractory lining maintenance and insulation repairs, significantly reducing maintenance complexity while maintaining the steam generation function
Solution Approach 2:
The invention changes the operational parameters of the furnace by using water-cooled walls that maintain lower temperatures, eliminating the high-temperature refractory environment that requires substantial maintenance. This parameter change from high-temperature refractory to water-cooled surfaces reduces maintenance requirements
3Reliability
If once through steam generators are used, then steam generation is provided, but uncooled supports for steam generation coils are required leading to high maintenance
Solution Approach 1:
The patent changes the thermal parameter of the support structures from uncooled to water-cooled, allowing them to operate at lower temperatures without thermal degradation. This eliminates the need for frequent maintenance of uncooled supports while maintaining structural integrity and steam generation capability
4Loss of energy
If drum boilers are used, then steam generation capability is provided, but it is expensive and time consuming to clean the tubes
Solution Approach 1:
The forced circulation system maintains continuous water flow through the evaporator tubes, which naturally prevents scale buildup and fouling. This self-cleaning effect through continuous circulation eliminates the need for expensive and time-consuming tube cleaning operations while maintaining thermal efficiency
Solution Approach 2:
The patent employs forced circulation to maintain continuous water flow through the evaporator tubes, ensuring that the heat transfer surfaces are constantly refreshed. This continuous action prevents fouling and scale deposition, eliminating the need for periodic cleaning shutdowns and maintaining sustained thermal efficiency
5Reliability
If drum boilers are used, then steam generation is achieved, but mechanical tube failures from water quality issues are expensive to repair
Solution Approach 1:
The forced circulation system continuously flows treated water through the evaporator tubes, preventing scale buildup and water quality-related corrosion. This continuous self-cleaning action prevents tube failures before they occur, eliminating expensive repair needs while maintaining reliable operation
Solution Approach 2:
The patent implements preliminary water treatment before water enters the evaporator, removing impurities that could cause tube failures. Combined with continuous forced circulation, this preliminary action prevents water quality issues before they can cause mechanical tube failures, avoiding expensive repairs
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The forced circulation steam generator achieves efficient steam production with reduced maintenance, lower operating costs, and improved reliability, capable of producing high quality steam with minimal blowdown and adaptable to varying water quality, enhancing heavy oil recovery processes.
Implementation Method 1
The water being pumped through the water cooled wall and the evaporator unit is heated and yields a water-steam mixture
Implementation Method 2
The water being pumped through the water cooled wall and the evaporator unit is heated
Implementation Method 3
The water-steam mixture is then directed to a steam drum that separates the steam from the water-steam mixture
Data Source
AI summary
An oil recovery process entails recovering an oil-water mixture from an oil bearing formation and separating the oil-water mixture to produce an oil product and produced water. The produced water includes suspended and dissolved solids and is subjected to treatment which removes suspended and dissolved solids therefrom. The treated water is then directed to a forced circulation steam generator that includes a furnace having a burner, water cooled walls and an evaporator unit. The treated water is pumped through the water cooled walls and the evaporator unit. The water passing through the water cooled walls and evaporator unit are heated to produce approximately 10% to approximately 30% quality steam in both the water cooled walls and the evaporator unit. The steam is collected and separated from a water-steam mixture to produce high quality steam, on the order of 95% or greater quality steam. This steam constitutes injection steam which is injected into an injection well to facilitate the recovery of the oil-water mixture.