Ethane Conversion in Propane Dehydrogenation
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Solution Overview
Problem
The existing propane dehydrogenation process generates ethylene as a by-product that is often used as fuel, leading to economic loss and an insufficient supply to meet current demand, as it primarily produces propylene with limited ability to separate and convert ethane and ethylene efficiently.
Innovation Solution
A method involving the separation of methane from ethane and ethylene using a demethanizer, followed by separation of ethane from ethylene using an ethane/ethylene splitter, and subsequent conversion of ethane to ethylene in an ethane reactor, with the reactant stream being cooled and neutralized before recycling back into the dehydrogenation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If by-products (methane, ethane, and ethylene) are removed via a de-ethanizer and recycled as fuel for a heating furnace, then the propylene preparation process can operate continuously, but valuable ethylene is wasted and economic efficiency is reduced
Solution Approach 1:
The patent changes the fate of ethylene from being burned as fuel to being separated and converted into useful products. By introducing a cracking unit that converts ethane to ethylene and a separation system that recovers ethylene, the process transforms waste by-products into valuable products, eliminating the contradiction between energy loss and productivity.
Solution Approach 2:
The patent converts the harmful waste (ethylene burned as fuel) into a beneficial resource (ethylene product). The by-products that were previously discarded are now fed into a cracking unit where ethane is converted to ethylene, which is then separated and sold as a valuable product, turning the waste stream into an additional revenue source.
2Productivity
If a conventional propane dehydrogenation process is used, then propylene can be produced efficiently, but ethylene demand cannot be met and economic value is lost
Solution Approach 1:
The patent makes the propane dehydrogenation process multi-functional by adding a cracking unit and separation system. The system now serves dual purposes: producing propylene through dehydrogenation and producing ethylene through cracking and separation. This allows the plant to adapt to market demands for both propylene and ethylene, resolving the contradiction between productivity and versatility.
Solution Approach 2:
The patent segments the product stream into separate propylene and ethylene production lines. By introducing a cracking unit that processes ethane separately and a separation system that divides the product stream, the process creates distinct production pathways for different products, enabling independent optimization and market adaptation.
3Ease of operation
If by-products are simply recycled as fuel, then the process is simple to operate, but valuable ethylene is destroyed and economic efficiency deteriorates
Solution Approach 1:
The patent introduces intermediary units (cracking unit and separation system) between the de-ethanizer and the heating furnace. Instead of directly burning the by-products, the system first cracks ethane to ethylene, then separates and recovers ethylene. This intermediary processing prevents the destruction of valuable ethylene while maintaining operational simplicity through standardized equipment.
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 method effectively converts ethane and ethylene by-products into valuable ethylene, improving economic efficiency and allowing for the production of both propylene and ethylene, enabling adjustments in operating conditions to meet market demands.
Implementation Method 1
passing a product stream containing methane, ethane, and ethylene, which are by-products generated in a de-ethanizer in a propane dehydrogenation process, through a demethanizer, thereby preferentially separating the methane
Implementation Method 2
separating the ethane from the ethylene by passing the reactant stream, from which the methane has been separated, through an ethane/ethylene splitter
Implementation Method 3
converting the ethane to ethylene by additionally allowing the separated ethane to react in an ethane reactor
Implementation Method 4
passing the reactant stream, which has passed through the ethane reactor, through a quenching tower, thereby cooling it
Data Source
Figure 1~2
AI summary
The present invention relates to a method of producing ethylene by separately collecting ethane and ethylene which are by-products of a propylene preparation process using propane dehydrogenation reaction and also combining an existing propylene preparation process with a process of converting ethane to ethylene. According to the present invention, valuable ethylene may be produced by converting most of ethane and ethylene, i.e., by-products of a propane dehydrogenation process, into ethylene without using the ethane as fuel, thereby improving process economic efficiency. Furthermore, a product line in the process of propane dehydrogenation reaction may be changed from a propylene product alone into two products, i.e., propylene and ethylene, and thus the operating conditions of a propylene dehydrogenation reactor and the operating conditions of a de-ethanizer may be adjusted according to the market situation, thereby increasing the production proportion of a favorable product line.