Methanol Distillation Revamp Using High Pressure Column Heat Integration
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Solution Overview
Problem
The existing methanol distillation plant refining section, comprising a medium pressure (MP) column and a low pressure (LP) column, lacks the capacity for significant production increases without incurring excessive capital costs or elevated energy consumption.
Innovation Solution
The introduction of a high pressure (HP) refining column operating at a pressure higher than the MP and LP columns, with gaseous streams of distilled methanol acting as heat sources for the MP and LP columns, and the export of water and fusel oil streams to maximize heat recovery and debottleneck the refining section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a new HP refining column is added to increase production capacity, then the capacity of the refining section is enhanced, but the device complexity and capital costs increase
Solution Approach 1:
The refining section is segmented into three distinct pressure levels (HP, MP, LP columns), with each column handling specific separation tasks. This segmentation allows capacity expansion while maintaining functional clarity and operational independence of each column.
Solution Approach 2:
The HP column is integrated into the existing MP-LP column configuration, with the HP column's bottom outlet feeding the MP column and its overhead condenser serving as the MP column's reboiler. This nested arrangement maximizes space utilization and heat recovery while adding capacity.
2Productivity
If the MP and LP columns operate at higher temperatures for faster distillation, then the distillation rate increases, but the energy consumption increases
Solution Approach 1:
The system establishes continuous heat circulation where overhead streams from each column continuously condense in the reboiler of the next lower-pressure column, providing continuous heating without external energy input for these stages.
Solution Approach 2:
The invention exploits phase transitions (vaporization and condensation) of methanol and water mixtures at different pressure levels. The overhead vapor from HP column condenses in MP reboiler, and overhead vapor from MP column condenses in LP reboiler, efficiently transferring latent heat through phase change.
3Productivity
If the existing MP and LP columns are operated at full capacity, then the current production is maintained, but the capacity for further increase is limited
Solution Approach 1:
The HP column is installed and integrated in advance, with its bottom outlet connected to the MP column and its overhead condenser serving as the MP reboiler. This preliminary configuration enables immediate capacity expansion without requiring subsequent modifications to the existing MP and LP columns.
Solution Approach 2:
The overhead condenser of the HP column serves dual functions: it condenses HP overhead stream and simultaneously acts as the reboiler for the MP column. Similarly, the MP overhead condenser serves as the LP reboiler. This multi-functionality reduces the need for separate heating and cooling equipment.
4Productivity
If more refining columns are added to increase capacity, then the production capacity increases, but the capital costs increase excessively
Solution Approach 1:
The invention merges the heating and cooling functions across columns by making the HP overhead condenser the MP reboiler and the MP overhead condenser the LP reboiler. This combining of functions reduces the total number of independent heat exchangers needed, lowering capital costs.
Solution Approach 2:
Each column's overhead stream self-provides the heating energy for the next lower-pressure column through condensation in its reboiler. This self-service arrangement eliminates the need for external steam heating for these columns, reducing utility infrastructure requirements and capital costs.
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 enhances the refining section's capacity while maintaining low energy consumption and capital costs, achieving higher methanol purity and optimizing heat recovery without overloading existing columns.
Implementation Method 1
installation of a line feeding a gaseous stream of distilled methanol withdrawn from the top of the HP column to at least one bottom boiler of the MP column, wherein the gaseous stream of distilled methanol acts as a heat source
Implementation Method 2
said MP refining column comprises a top outlet line for a gaseous stream of distilled methanol and a bottom outlet line for a solution containing methanol
Implementation Method 3
installation of a high pressure (HP) refining column arranged to operate at a third distillation pressure (p3), wherein p3 is higher than p1
Implementation Method 4
a refining column separates one or more light products (i.e. having a relatively low boiling temperature, e.g. methanol) at the top from one or more heavy products (i.e. having a relatively high boiling temperature, e.g. water) at the bottom
Data Source
AI summary
Method for revamping a refining section of a methanol distillation plant comprising a medium pressure (MP) column a low pressure (LP) column, wherein both said columns comprise at least one bottom boiler, a gaseous stream of distilled methanol withdrawn from the MP column is fed to at least one bottom boiler of the LP column and a liquid solution containing methanol withdrawn from the MP column is fed to the LP column, the method of revamping comprising the installation of a high pressure (HP) column; the installation of a line feeding a gaseous stream of distilled methanol from the HP column to at least one bottom boiler of the MP column and the installation of a bottom line for exporting from the HP column a liquid stream consisting essentially of water.