Olefin Separation Sequence Inversion for Refrigerant Reduction
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Solution Overview
Problem
The economics of oxygenate-to-olefin (OTO) processes, particularly methanol-to-propylene (MTP) processes, are hindered by high investment and operating costs due to the complexity and inefficiency of the separation sequence in the work-up section, which requires significant refrigerant use and energy consumption for cooling and drying processes.
Innovation Solution
The process rearranges the separation sequence by placing the deethanizer upstream of the depropanizer, allowing for the use of chilled water instead of propylene refrigerant in the depropanizer overhead condenser, and separates streams to minimize refrigerant consumption and drying requirements, thereby reducing the size and energy needs of the refrigerant system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the conventional separation sequence (depropanizer before deethanizer) is used, then the separation of C3 hydrocarbons can be performed, but significant refrigerant consumption and high energy costs are required for cooling and drying processes
Solution Approach 1:
The patent inverts the conventional separation sequence by placing the deethanizer upstream of the depropanizer. This reversal allows the depropanizer overhead condenser to operate at higher temperatures using chilled water instead of propylene refrigerant, significantly reducing energy consumption while maintaining separation performance.
Solution Approach 2:
The patent changes the operating parameters of the separation sequence, specifically the temperature and pressure conditions in the depropanizer overhead condenser. By operating at higher temperatures enabled by the inverted sequence, the system can use chilled water (higher temperature cooling medium) instead of propylene refrigerant (lower temperature cooling medium), reducing energy consumption.
2Manufacturing precision
If the conventional separation sequence is used, then complete separation can be achieved, but large system size and high investment costs are required
Solution Approach 1:
The inverted separation sequence allows for more efficient heat integration and reduces the cooling capacity requirements. This enables smaller refrigeration systems and reduces investment costs while maintaining complete separation performance through optimized operational parameters.
Solution Approach 2:
The deethanizer performs preliminary separation of C2 hydrocarbons before the depropanizer processes the stream. This preliminary action reduces the load on subsequent separation units and minimizes the overall system size required to achieve complete separation.
3Temperature
If propylene refrigerant is used in the depropanizer overhead condenser, then effective cooling can be achieved, but high operating costs and significant refrigerant consumption occur
Solution Approach 1:
By inverting the separation sequence, the depropanizer overhead condenser can operate at higher temperatures where chilled water is effective, eliminating the need for propylene refrigerant and its associated compression and consumption issues.
Solution Approach 2:
The patent replaces the expensive propylene refrigerant system with a simpler chilled water cooling system. Chilled water is a cheaper, readily available cooling medium that eliminates refrigerant consumption and the need for complex refrigeration 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 configuration significantly reduces investment and operating costs by minimizing refrigerant consumption and system size, while maintaining separation performance, making smaller OTO systems economically viable.
Implementation Method 1
a quench system is used in the first step. Quenching refers to a sudden or shock cooling, usually achieved through direct heat exchange with a fluid quench medium.
Implementation Method 2
The work-up section typically consists of a series of interconnected distillation and/or rectification columns.
Data Source
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AI summary
In a process for the production of olefins from oxygenates, comprising the steps of: (i) heterogeneously catalyzed conversion of the oxygenates to a product stream containing water, olefins and other hydrocarbons and at least one oxygenate, (ii) quenching of the product stream, yielding one or more streams comprising olefins, these olefin-containing streams are, according to the invention, first fed to a debutanizer, then to a deethanizer, then to a depropanizer, and finally to a C3 splitter. In this way, the separation sequence can be simplified and the energy and coolant requirements of the separation columns reduced.