NIR Spectroscopy for Vapor Phase Stream Analysis
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Solution Overview
Problem
Conventional methods for analyzing vapor phase process streams in steam reforming of hydrocarbons face challenges such as condensation issues with gas chromatography and the need for high-temperature equipment, which complicates achieving precise compositional data and controlling carbon monoxide to hydrogen ratios in synthesis gas production.
Innovation Solution
The method involves taking a slipstream from the process stream, cooling it above its dew point to maintain components in the vapor phase, and using near-infrared (NIR) spectroscopy to analyze and correlate spectra with established calibration models to determine component concentrations or partial pressures, allowing for precise compositional analysis and process control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gas chromatography is used to analyze vapor phase process streams, then compositional data can be obtained, but condensation of components such as steam occurs which reduces measurement precision
Solution Approach 1:
The patent changes the physical state parameter of the process stream by cooling it from high temperature vapor phase to liquid phase below dew point before analysis. This parameter change prevents condensation during analysis while maintaining measurement accuracy, as the stream is already in liquid phase and properly conditioned for chromatographic separation.
Solution Approach 2:
The patent applies preliminary cooling and phase change action before the actual compositional analysis. By pre-cooling the stream below its dew point and condensing vapor components before injection into the gas chromatograph, the system prepares the sample in an optimal state for analysis, preventing condensation issues during the measurement process itself.
2Object-affected harmful factors
If the process stream is maintained in vapor phase during analysis, then condensation is avoided, but equipment capable of withstanding high temperatures is required which increases device complexity and cost
Solution Approach 1:
The patent performs preliminary cooling and condensation of the vapor phase stream before analysis. By transforming the stream to liquid phase below dew point prior to injection, the system eliminates the need for high-temperature resistant analysis equipment, using standard gas chromatography instruments operated at conventional temperatures.
Solution Approach 2:
The patent changes the temperature and phase parameters of the process stream from high-temperature vapor phase to lower-temperature liquid phase before analysis. This parameter transformation allows the use of standard, less complex analytical equipment while maintaining measurement accuracy.
3Quantity of substance
If conventional absorption stripping is used to separate carbon dioxide, then carbon dioxide removal is achieved, but the process complexity and equipment requirements increase
Solution Approach 1:
The patent replaces the mechanical separation system (absorption stripping columns, compressors) with a chemical substitution approach. By introducing a catalyst that promotes the water-gas shift reaction, carbon dioxide is converted to carbon monoxide and hydrogen through chemical transformation, eliminating the need for complex mechanical separation equipment.
Solution Approach 2:
The patent changes the chemical composition parameters of the synthesis gas by promoting the water-gas shift reaction. This chemical parameter change converts carbon dioxide into desirable products (carbon monoxide and hydrogen), transforming a separation problem into a chemical conversion problem that simplifies the overall process.
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 enables precise compositional data and real-time process control, improving the efficiency of steam reforming by adjusting feed component flow rates to optimize carbon monoxide production and minimize carbon dioxide production.
Implementation Method 1
uses an infrared spectrophotometer to analyse and control the hydrocarbons feeding a cracking furnace and thus the yields as a function of this analysis. The chemical process is industrial steam-cracking in which the space time yield of the products is controlled with the help of near infrared absorbance measurements
Implementation Method 2
cooling it above its dew point to maintain components in the vapor phase
Data Source
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AI summary
A method for the on-line analysis of a process stream, which process stream is a feedstream to or an exit stream from a steam reformer, which process stream has a temperature of at least 2000C, the components of which process stream are in the vapour phase, which method comprises: (a) taking a slipstream from the process stream; (b) cooling the slipstream to a temperature above its dew point; (c) analysing the cooled slipstream by near infra-red (NIR) spectroscopy to obtain a spectrum characterising NIR-absorbing components of the process stream; and (d) correlating the spectrum obtained to established calibration models from NIR spectroscopy using chemometric techniques to determine the concentration of, and/or to determine the partial pressure of one or more of the NIR-absorbing components of the process stream.