Multi-Circulation Boiler for SAGD Steam Delivery
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Solution Overview
Problem
Boilers used in Steam Assisted Gravity Drainage (SAGD) processes face challenges in delivering steam at high pressure to deeper wells and managing feedwater quality, particularly with sub-ASME quality water containing volatile and non-volatile organic components and high silica levels, which can lead to deposition issues and reduced performance.
Innovation Solution
The design incorporates a multi-circulation boiler system with separate clean and concentrated sections, utilizing internal dividers and channels to separate feedwater circulation loops, allowing high-quality water to flow through high heat flux zones and low-quality water through low heat flux zones, reducing deposition and enabling natural circulation without mechanical pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sub-ASME quality feedwater is used in conventional boilers, then boiler capacity and steam generation are maintained, but deposition occurs and reliability decreases
Solution Approach 1:
The boiler is divided into separate clean section and concentrated section circulation loops, with internal dividers creating distinct zones. This segmentation allows different water qualities to be processed simultaneously, preventing deposition in the clean section while maintaining boiler capacity.
Solution Approach 2:
Different regions of the boiler are assigned different water qualities - the clean section receives high-quality water for steam generation, while the concentrated section handles low-quality water. This local differentiation of water quality prevents deposition in critical steam generation zones.
2Stress or pressure
If mechanical pumps are used to force circulation, then steam delivery pressure is increased, but device complexity and energy consumption increase
Solution Approach 1:
The boiler circulation system operates without mechanical pumps, using natural circulation principles where water and steam flow is driven by density differences and gravity. The system self-regulates flow patterns through natural convection currents, eliminating the need for external pumping equipment.
Solution Approach 2:
Mechanical pump systems are replaced with natural circulation mechanisms. The circulation is driven by thermal and gravitational forces rather than mechanical propulsion, substituting a complex mechanical system with a simpler passive thermal-hydraulic system.
3Use of energy by moving object
If high heat flux zones are exposed to low-quality water, then heat transfer efficiency is improved, but deposition increases and reliability decreases
Solution Approach 1:
The steam generating banks are segmented into clean section and concentrated section zones, allowing high-quality water to be dedicated to high heat flux areas where steam generation occurs, while low-quality water is routed to lower heat flux zones.
Solution Approach 2:
High-quality water is locally assigned to clean sections with high heat flux zones for efficient steam generation, while low-quality water is assigned to concentrated sections with lower heat flux zones, preventing deposition in critical steam generation areas.
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
This design effectively manages feedwater quality, reduces deposition, and enhances steam delivery efficiency, particularly in SAGD processes, by maintaining boiler water quality and allowing for flexible heat flux exposure, thus improving operational reliability and efficiency.
Implementation Method 1
The furnace, the clean section steam generating bank, and the concentrated section steam generating bank may operate by natural circulation, and do not contain mechanical pumps.
Implementation Method 2
Each of the three drums contains an internal divider that divides the drum into a clean section and a concentrated section
Implementation Method 3
Tubes in a front portion of the furnace sidewall and a front portion of the baffle wall extend between the intermediate drum channel and the lower drum channel
Implementation Method 4
clean section steam generating bank and a concentrated section steam generating bank
Data Source
AI summary
A boiler includes an upper steam drum, an optional intermediate drum, and a lower drum. Each drum is divided by an internal divider into a clean section and a concentrated section. Downcomers connect the upper steam drum to the lower drum, and tubes are connected to convey a heated steam-water mixture from the lower drum into the upper steam drum (through the optional intermediate drum, if provided). An optional superheater has an input terminal connected to receive steam from the clean section of the upper steam drum. An attemperator may be provided to attemperate superheated steam output from an output terminal of the superheater, and the attemperation fluid may optionally be provided from the concentrated side of the upper steam drum.