Integrated Propane Dehydrogenation and Polymerization Gas Recovery
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Solution Overview
Problem
Conventional processes for producing propylene and polypropylene are energy-intensive and inefficient, with high capital and operating costs due to the need for separate units and energy-intensive gas separation and recycling processes.
Innovation Solution
An integrated process that combines propane dehydrogenation and propylene polymerization, sharing product gas compressors and cold boxes to reduce energy consumption and eliminate the need for separate equipment, allowing direct recycling of unreacted propane and propylene without pressurization or liquefaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate dehydrogenation and polymerization units are used, then process reliability is improved, but device complexity and capital costs increase
Solution Approach 1:
The patent combines the dehydrogenation unit and polymerization unit into a single integrated system where the dehydrogenation reactor and polymerization reactor share common equipment including compressors, cold boxes, and separation systems. This merging eliminates the need for separate standalone units while maintaining process reliability through integrated operation.
Solution Approach 2:
The integrated system employs multi-functional equipment that serves both dehydrogenation and polymerization processes. For example, the same compressor handles gases from both reactors, the cold box cools streams from both units, and the separation system processes effluents from both reactions, thereby reducing overall device complexity.
2Measurement precision
If gas membrane separation unit is used for purge gas separation, then separation precision is improved, but energy consumption increases
Solution Approach 1:
The patent extracts the light hydrocarbon separation function from the energy-intensive gas membrane separation unit and integrates it into the existing distillation train of the dehydrogenation unit. The C3 splitter and other separation columns already present in the dehydrogenation section handle the separation of light hydrocarbons from purge gas, eliminating the need for additional membrane separation equipment and its associated compressor energy consumption.
3Adaptability or versatility
If compressor is sized for full output, then adaptability is improved, but energy consumption increases
Solution Approach 1:
The integrated system employs dynamic operation where the compressor sizing and operating conditions are optimized based on actual process requirements rather than designing for maximum theoretical output. The system adapts its compression capacity to match the actual gas flows from both dehydrogenation and polymerization reactors, avoiding the energy penalty of oversized compressors operating at partial load.
4Manufacturing precision
If separate recovery process is used for carrier gas, then purification precision is improved, but device complexity and costs increase
Solution Approach 1:
The patent merges the carrier gas recovery process with the existing dehydrogenation effluent treatment system. The carrier gas, along with other off-gases from polymerization, is routed through the same compression, cooling, and separation train used for dehydrogenation products. This eliminates the need for a separate dedicated recovery process while maintaining adequate purification precision for reusable gases.
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
Significantly reduces energy and capital costs, achieving more economical production of polypropylene by integrating product and utility flows, and optimizing gas separation processes.
Implementation Method 1
The separating comprises compressing the dehydrogenated effluent in a product gas compressor
Implementation Method 2
cooling the compressed effluent in a cold box
Implementation Method 3
separating the cooled, compressed effluent in a deethanizer and a C3 splitter
Implementation Method 4
separating the cooled, compressed effluent in a deethanizer and a C3 splitter
Implementation Method 5
independently passing the purge gas and carrier gas through the cold box, thereby cooling the purge gas and carrier gas
Implementation Method 6
condensing, in the cold box, a portion of the carrier gas and a portion of the purge gas
Implementation Method 7
In the polymerization zone, propylene is reacted to produce a polymerization product
Data Source
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AI summary
Embodiments disclosed herein relate to the production of polypropylene. A hydrocarbon feedstock, containing propane, is fed to a propane dehydrogenation reaction zone to convert a portion of the propane to propylene. The propane and propylene are separated, and at least a portion of the propylene stream is fed to a polymerization zone. In the polymerization zone, propylene is reacted to produce a polypropylene. Additionally, a purge gas and a carrier gas are recovered. The purge and carrier gases are fed to the separation system and cooled against a second portion of the propylene stream.