Sulfur Recovery Control System with Multi-Location Gas Analysis
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Solution Overview
Problem
Conventional sulfur recovery processes, such as the Claus process, face inefficiencies due to delays in detecting composition changes in process gases, leading to reduced sulfur recovery rates during upset conditions, as the control systems rely on tail gas analysis with significant time lags, resulting in suboptimal oxygen management.
Innovation Solution
A control process and system that analyzes the process gas composition at multiple locations, allowing for real-time adjustment of oxygen levels to maintain optimal hydrogen sulfide to oxygen ratios, reducing the duration and amplitude of upset effects by combining feed forward and feedback control mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If tail gas analysis is used for control, then sulfur recovery rate can be improved, but time delay increases significantly
Solution Approach 1:
The patent applies preliminary action by analyzing process gas composition at multiple locations upstream (including immediately upstream of the thermal step and upstream of the catalytic step) before the gas becomes tail gas. This allows the control system to detect composition changes and adjust oxygen levels proactively, rather than waiting for tail gas analysis which occurs after the fact. The preliminary measurements enable faster response to upset conditions while maintaining accurate sulfur recovery control.
2Device complexity
If single location analysis is used, then device complexity is reduced, but measurement accuracy deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the process gas stream into multiple monitoring locations: immediately upstream of the thermal step, upstream of the catalytic step, and in the tail gas. Each location provides complementary information about different stages of the sulfur recovery process. This segmented approach enables more precise detection of composition changes and better identification of upset conditions while maintaining manageable system complexity through modular analyzer placement.
Solution Approach 2:
The patent adds a spatial dimension to the control system by implementing multi-location analysis rather than single-point measurement. By measuring composition at multiple positions along the process flow (different spatial locations), the system gains enhanced capability to detect and characterize composition changes, providing both temporal and spatial resolution for more accurate process control.
3Productivity
If oxygen levels are not及时调整, then sulfur recovery efficiency decreases, but system stability is compromised
Solution Approach 1:
The patent implements feedback control by continuously measuring process gas composition at multiple locations and using this information to adjust oxygen levels in real-time. The control system monitors composition changes and provides feedback to the oxygen control mechanism, enabling dynamic adjustment to maintain optimal hydrogen sulfide to oxygen ratios. This feedback loop ensures both high sulfur recovery efficiency and process stability by preventing prolonged upset conditions.
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 significantly enhances sulfur recovery efficiency by promptly adjusting oxygen levels in response to composition changes, minimizing the impact of upset conditions and maintaining optimal process conditions.
Implementation Method 1
a first analyzing a composition of the process gas stream at a first location between the beginning of the thermal step and the end of the catalytic step; b. first controlling the amount of the oxygen containing gas having regard to the composition of the process gas stream at the first location
Implementation Method 2
The first step in the Claus process is a thermal step which combines the process gas containing the hydrogen sulfide with air or an oxygen containing gas and heating it to the necessary temperature for combustion. The following reactions both occur in the thermal step: H2S+ 3/2O2→SO2+H2O
Implementation Method 3
The catalytic step combines the products from the thermal step and hydrogen sulfide with a catalyst which results in the production of elemental sulfur and a tail gas which includes a relatively small amount of hydrogen sulfide. The following reaction is the predominant reaction which occurs in the catalytic step: 2H2S+SO2→3S+2H2O
Data Source
AI summary
In a process and system for recovering sulfur from a process gas stream initially comprising a hydrogen sulfide containing gas and an oxygen containing gas, a control process and system respectively are provided. The sulfur recovery process includes a thermal step having a beginning followed by a catalytic step having an end. The control process includes first analyzing a composition of the process gas stream at a first location between the beginning of the thermal step and the end of the catalytic step, first controlling the oxygen containing gas having regard to that first composition, second analyzing the composition of the process gas stream at a second location downstream of the end of the catalytic step, and second controlling the oxygen containing gas having regard to that second composition. The sulfur recovery system and control system therefor are provided for performing the steps of the sulfur recovery process and control process respectively.