Polyolefin Flash Vessel for Reactor Dump Recovery
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Solution Overview
Problem
In polyolefin production, reactor dumps during upset conditions result in significant loss of polyolefin product due to undersized conventional diluent recovery systems, leading to flaring of flashed hydrocarbons and disposal of polyolefin solids, representing up to 1% of total production.
Innovation Solution
Combining the flash vessel and alternate flash tank into a single vessel, allowing for continuous take-off discharge of the reactor, which recovers polyolefin product solids and recycles flashed hydrocarbons, reducing capital and operating costs by eliminating a vessel and optimizing particle size distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a separate alternate flash tank is used for reactor dumps, then polyolefin product can be recovered during upset conditions, but capital costs and device complexity increase due to additional vessel requirements
Solution Approach 1:
The patent combines the alternate flash tank functionality into the existing flash vessel by configuring the flash vessel to receive both normal continuous take-off discharge and reactor dump discharge. This eliminates the need for a separate alternate flash tank while maintaining the ability to recover polyolefin product during reactor dumps, thus reducing capital costs and device complexity without compromising product recovery
Solution Approach 2:
The flash vessel is designed to perform multiple functions: it serves as the normal flash vessel for continuous take-off discharge and simultaneously functions as the alternate flash tank for reactor dump discharge. This multi-functionality eliminates the need for dedicated separate equipment while ensuring polyolefin product recovery during upset conditions
2Device complexity
If conventional diluent recovery systems are used for reactor dumps, then system design is simplified, but significant polyolefin product is lost due to undersized recovery capacity
Solution Approach 1:
The flash vessel is designed with dynamic capacity to accommodate varying discharge rates from both normal continuous take-off operations and reactor dump events. The system can adapt its processing capacity based on the incoming discharge volume and rate, ensuring adequate recovery during high-volume reactor dumps without requiring an oversized dedicated system for all conditions
3Productivity
If reactor dump contents are not processed, then operating costs are reduced, but production losses increase due to disposal of polyolefin solids and flaring of hydrocarbons
Solution Approach 1:
The patent converts what would normally be harmful waste disposal actions (flaring of hydrocarbons and disposal of polyolefin solids) into beneficial recovery operations. By processing reactor dump contents through the flash vessel, the system recovers polyolefin product solids that would otherwise be discarded and handles hydrocarbons that would otherwise be flared, thus turning a loss scenario into a recovery opportunity
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 enhances polyolefin recovery, reduces flare size requirements, and minimizes production losses by processing reactor dump contents in the flash vessel, thereby lowering capital and operating costs while improving particle size distribution.
Implementation Method 1
discharge from the polymerization reactor to a flash vessel... separation of the flashed hydrocarbon diluent and the polyolefin product solids
Data Source
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AI summary
A flash chamber sized to receive the effluent discharged from a polyolefin reactor during normal operation of the reactor and during a reactor dump, advantageously eliminating a reactor dump tank or alternate flash tank from the equipment outlay of a polyolefin manufacturing process. The flash chamber is sized to hold at least the polyolefin solids discharged from the reactor. A condenser fluidically coupled to an overhead portion of the flash chamber is sized to condense the flow rate of vaporized hydrocarbon (e.g., diluent, monomer, etc.) discharged overhead from the flash chamber during normal operation and during the reactor dump.