Scale suppression apparatus, geothermal power generation system using the same, and scale suppression method
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Solution Overview
Problem
Geothermal power generation systems face challenges in suppressing silica scale formation due to high calcium and silica content in hot water, leading to scaling issues and pipe erosion, with existing methods like sulfuric acid injection being costly and inefficient, and requiring large amounts of expensive chelating agents.
Innovation Solution
A scale suppression apparatus that alternates between adding a chelating agent and an alkaline agent to raise pH above 7 and an acid substance to lower pH below 7, using a controller to manage the switching, minimizing the use of expensive chelating agents and effectively dissolving amorphous silica and compounds, while a scale detection unit monitors and adjusts the process based on pressure and flow rate thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulfuric acid injection method is used to suppress silica scale, then the polymerization rate of silica is suppressed, but piping is eroded with acid and sulfate ion density increases causing other scale precipitation
Solution Approach 1:
The patent changes the pH parameter dynamically by alternating between acid injection (lowering pH) and alkaline agent injection (raising pH). This periodic parameter change allows suppression of silica polymerization during acid phases while dissolving precipitated compounds during alkaline phases, preventing both silica scale and other scale formations without continuous acid exposure that causes erosion.
Solution Approach 2:
The patent implements periodic action by alternately injecting acid substances and alkaline agents in cycles. During acid injection phases, silica polymerization is suppressed; during subsequent alkaline agent phases, any precipitated compounds are dissolved. This periodic alternation prevents continuous harmful effects of acid erosion while maintaining scale suppression effectiveness.
2Reliability
If large amount of chelating agent is injected to prevent calcium silicate hydrates generation, then CSH generation is prevented, but the cost increases significantly
Solution Approach 1:
The patent applies partial action by injecting alkaline agents in controlled amounts during specific phases rather than continuously. The alkaline agent is injected sufficiently to dissolve precipitated compounds and maintain CSH prevention, but not in excessive amounts that would waste resources. This controlled partial injection reduces chelating agent consumption while maintaining effectiveness.
Solution Approach 2:
The patent changes the pH parameter periodically using alkaline agents during specific phases of the cycle. This temporal parameter change allows prevention of CSH generation only when necessary (during and after acid injection phases when precipitation risk is highest), rather than maintaining high alkalinity continuously, thereby reducing overall chelating agent consumption.
3Reliability
If alkaline agent is injected continuously to maintain high pH, then silica scale is suppressed, but compounds such as CSH precipitate due to reaction with polyvalent metal ions
Solution Approach 1:
The patent implements periodic action by alternating between acid injection phases and alkaline agent injection phases. During acid phases, pH is lowered to prevent CSH precipitation. During subsequent alkaline phases, pH is raised to dissolve any precipitated compounds and suppress silica scale. This periodic alternation prevents continuous alkaline exposure that would cause compound precipitation while maintaining silica scale suppression during alkaline phases.
Solution Approach 2:
The patent dynamically changes the pH parameter by alternating between low pH (acid injection) and high pH (alkaline agent injection) states. This parameter oscillation prevents sustained high pH conditions that would cause CSH precipitation, while still achieving silica scale suppression during the alkaline phases when needed.
4Reliability
If acid substance is injected continuously to maintain low pH, then compound precipitation is prevented, but amorphous silica precipitates and chelating agent effectiveness decreases
Solution Approach 1:
The patent implements periodic action by alternating between acid injection phases (low pH) and alkaline agent injection phases (high pH). During acid phases, compounds are dissolved and prevented from precipitating. During subsequent alkaline phases, amorphous silica that may have precipitated during acid phases is dissolved, and silica scale suppression is enhanced. This periodic alternation prevents continuous acid exposure that would cause silica precipitation while maintaining compound dissolution.
Solution Approach 2:
The patent dynamically changes the pH parameter by oscillating between low pH states (acid injection for compound dissolution) and high pH states (alkaline agent injection for silica management). This parameter oscillation prevents sustained low pH conditions that would cause amorphous silica precipitation, while still achieving compound dissolution during acid phases.
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 approach effectively suppresses silica and calcium-based scale formation over the long term, reducing maintenance needs and costs by minimizing the use of chelating agents and maintaining efficient operation of geothermal power generation systems.
Implementation Method 1
a chelating agent and an alkaline agent are added to the influent water
Implementation Method 2
adding a chelating agent and an alkaline agent to the influent water to make the influent water higher than pH 7
Implementation Method 3
an acid substance is added to the influent water to make the influent water lower than pH 7
Implementation Method 4
amorphous silica of super saturation is precipitated
Implementation Method 5
the solubility of amorphous silica becomes higher as the alkalinity become higher
Implementation Method 6
the precipitated amorphous silica can be dissolved... Both the amorphous silica and the compounds can be dissolved alternately
Data Source
AI summary
A scale suppression apparatus capable of suppressing in a low-priced manner the generation of silica-based scale and calcium-based scale in the influent water, a geothermal power generation system using the same, and a scale suppression method are provided. The apparatus includes a first addition unit configured to add liquid containing a chelating agent and an alkaline agent to influent water flowing through a pipe arrangement to make the influent water higher than pH 7, a second addition unit configured to add an acid substance to the influent water to make the influent water lower than pH 7, and a controller configured to alternatively switch between the operation of the first addition unit and the operation of the second addition unit. The controller controls the switching of the first addition unit and the second addition unit based on the signals output from a scale detection unit and a pH meter.