Pyrolysis Contaminant Management via Sorbent Adsorption
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Solution Overview
Problem
Pyrolysis processes, such as steam cracking, face challenges in handling hydrocarbon feeds containing contaminant-containing compositions like methanol, acetone, phenol, and acetaldehyde, which lead to process disruptions, saturation of sorbents, and potential system shutdowns due to the introduction of low-value raw feedstocks.
Innovation Solution
The process involves determining the amount of contaminants in the hydrocarbon feed based on its composition, temperature, and residence time during steam cracking, and using sorbents and additives to manage and separate these contaminants effectively, allowing the sorbents to operate without saturation and preventing fouling in the pyrolysis system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If low value raw feedstocks (C5+ hydrocarbons) are used as hydrocarbon feed to the pyrolysis unit, then feedstock cost is reduced, but contaminant-containing compositions (oxygenates like methanol, acetone, phenol, acetaldehyde) are introduced into the pyrolysis process causing process disruptions and potential system shutdowns
Solution Approach 1:
The patent determines the amount of contaminants that will be present in the steam cracker effluent based on the composition of the hydrocarbon feed, temperature, and residence time before processing. This preliminary determination allows for proactive management of contaminant levels and prevents unexpected process disruptions
Solution Approach 2:
The patent introduces sorbent materials as intermediaries to capture and remove contaminant-containing compositions from the pyrolysis process. The sorbent acts as a mediator between the contaminated feedstock and the pyrolysis system, preventing contaminants from causing process disruptions while allowing the beneficial use of low-value feedstocks
2Reliability
If sorbent is used to remove methanol from depropanizer overhead, then process reliability is improved, but sorbent saturation occurs requiring replacement or re-activation
Solution Approach 1:
The patent introduces a sufficient amount of sorbent into the sorbent contactor to allow processing for at least as long as a predetermined period of time without requiring replacement. This excessive action ensures that the sorbent capacity exceeds the contaminant load, extending service life and reducing maintenance frequency
3Productivity
If steam cracking is performed on hydrocarbon feed containing methanol, then production continues, but methanol contaminates the pygas product requiring separation and reducing product quality
Solution Approach 1:
The patent separates methanol from the pygas product through a series of extraction and separation steps. The depropanizer overhead is contacted with sorbent to remove methanol, and the naphtha cut is separated into pygas and aqueous mixture phases, effectively extracting the contaminant from the desired product
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 the pyrolysis process to run continuously for extended periods by effectively managing contaminant-containing compositions, reducing the risk of system shutdowns and maintaining process efficiency by separating and processing contaminants within the steam cracker effluent.
Implementation Method 1
introducing a sufficient amount of a first sorbent into a first methanol sorbent unit to allow the first methanol sorbent unit to process a depropanizer overhead
Implementation Method 2
steam cracking a hydrocarbon feed that includes methanol to produce a steam cracker effluent that can include cracked hydrocarbons and methanol
Implementation Method 3
The aqueous mixture can be contacted with steam to produce a vapor phase product that can include ≥80 wt. % of the methanol in the aqueous mixture and a liquid phase product that can include ≤20 wt. % of the methanol in the aqueous mixture
Data Source
AI summary
Processes for upgrading a hydrocarbon for a predetermined period of time. The process can include determining an amount of one or more contaminant-containing compositions that will be present in a pyrolysis effluent based, at least in part, on a composition of a hydrocarbon feed to be steam cracked, a temperature the hydrocarbon feed will be heated at during steam cracking, a residence time the hydrocarbon feed will be heated at the temperature during steam cracking, or a combination thereof. In some examples, the process can also include taking one or more steps to allow the hydrocarbon feed to be steam cracked for at least as long as a predetermined period of time, controlling process conditions within one or more separation stages to favor certain product compositions, introducing a predetermined amount of one or more agents into various locations of the process, or any combination thereof.