Alkalinity Analysis in Glycol Recovery via pH and CO2 Pressure
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Solution Overview
Problem
Existing methods for determining alkalinity in aqueous solutions, particularly in glycol-containing liquids used in petroleum recovery, are inaccurate and cumbersome due to interference from weak bases, CO2 saturation, and foam generation, which complicates pH measurements and titration processes.
Innovation Solution
A method and apparatus that measure total alkalinity by controlling CO2 pressure and pH in a calibrated container, using the equation Total alkalinity = K * (pCO2 / 10 - pH, with K defined by temperature, pressure, and ion concentration, to accurately calculate OH-, CO32-, and HCO32- contributions, while ensuring CO2 is not chemically bonded, using inert gases and vacuum to prepare the sample.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If titration with acid is used to determine alkalinity, then alkalinity can be measured, but the method fails when the solution contains bases weaker than bicarbonate and is interfered with by salts of weak organic acids
Solution Approach 1:
The invention changes the measurement parameters by using pH measurements at two different temperatures (25°C and 0°C) instead of traditional titration. This temperature-based parameter change allows differentiation of alkalinity components (OH-, CO32-, HCO3-) even in the presence of weak bases and organic acid salts, resolving the reliability issue while maintaining measurement precision
Solution Approach 2:
The invention introduces temperature as an intermediary variable to indirectly determine alkalinity composition. By measuring pH at two temperatures and using the temperature dependence of equilibrium constants, the method calculates alkalinity components without direct chemical reaction, avoiding interference from weak bases and organic acid salts
2Measurement precision
If CO2 is bubbled through the solution to saturate it for alkalinity determination, then alkalinity can be measured, but the amount of CO2 added is not known and bubbles generate foam making measurements difficult
Solution Approach 1:
The invention replaces the mechanical/bubbling method of CO2 addition with a controlled CO2 sparging system that precisely delivers a predetermined amount of CO2. This substitution eliminates foam generation from excessive bubbling while ensuring accurate CO2 dosage, thereby improving both measurement precision and ease of operation
Solution Approach 2:
The invention performs preliminary action by pre-determining the exact amount of CO2 to be added based on the known volume and initial pH of the sample. This preliminary calculation allows precise CO2 addition before measurement, avoiding the trial-and-error bubbling process and eliminating foam-related measurement difficulties
3Measurement precision
If traditional alkalinity determination methods are used in glycol recovery systems, then alkalinity can be measured, but the process is cumbersome and inaccurate due to interference from weak bases and organic acid salts
Solution Approach 1:
The invention enables self-service measurement by using the inherent temperature dependence of pH and equilibrium constants in the glycol solution itself. The system requires no external reagents or complex titration apparatus, simply measuring pH at two temperatures to calculate alkalinity components, thereby reducing device complexity while improving precision in glycol recovery systems
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 provides a robust, precise, and repeatable process for determining alkalinity with high accuracy, reducing chemical usage and minimizing corrosion and scaling issues in glycol recovery systems.
Implementation Method 1
measuring a pH value of the aqueous liquid sample
Implementation Method 2
measuring a pressure value in the container
Implementation Method 3
Total alkalinity = K * (pCO2 / 10 - pH, with K defined by temperature, pressure, and ion concentration, to accurately calculate OH-, CO32-, and HCO32- contributions
Data Source
Figure 1
AI summary
Method for analyzing the alkalinity conditions in aqueous liquids, comprising: sampling a known amount of the aqueous liquid and placing it in a container of known volume, measuring pH in the sampled liquid and pressure in the container, adding a known amount of C02 to the sampled liquid, and measuring pH in the sampled liquid and the pressure in the container, and finally calculating the total alkalinity based on the values from the performed measurements. An apparatus for conducting the method is also described as well as a method for controlling chemistry of a glycol containing liquid in a system for recovery of glycol.