Low-Temperature Heat Recovery in Aromatic Complexes
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Solution Overview
Problem
Current refining and petrochemical processes inefficiently utilize low-pressure steam generated at 100-180°C, which is considered lost heat, leading to high energy consumption and costs.
Innovation Solution
Generating low-pressure steam from heat sources in refining or petrochemical processes, recompressing it to medium pressure, and using it as a heat transfer fluid to reduce energy consumption by lowering the operating temperature of reboilers and preheaters, thereby optimizing heat usage across the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If low-temperature heat (100-180°C) is directly used for heat exchange with cold process fluids, then heat utilization efficiency improves, but the temperature difference is insufficient to enable effective heat transfer
Solution Approach 1:
The invention changes the temperature parameter by compressing the low-temperature vapor to raise its temperature, making it suitable for heat exchange with cold process fluids. The compression process transforms the thermal state of the vapor from 100-180°C to a higher temperature range, enabling effective heat transfer.
Solution Approach 2:
The invention introduces a compression device as an intermediary between the low-temperature heat source and the heat exchange system. This intermediary component raises the temperature of the vapor before it enters the heat exchanger, enabling the heat transfer process to occur effectively.
2Temperature
If operating pressure of distillation columns is increased to raise vapor temperature, then heat transfer efficiency improves, but heat consumption by reboiler increases
Solution Approach 1:
Instead of increasing operating pressure to raise temperature (conventional approach), the invention inverts the approach by maintaining low operating pressure and using external compression to achieve the required temperature for heat exchange. This avoids the increased reboiler heat consumption that would result from high-pressure operation.
Solution Approach 2:
The invention segments the temperature-raising function from the distillation process itself. Rather than raising temperature through pressure increase within the distillation column, the temperature elevation is achieved separately through compression of the overhead vapor, allowing the distillation column to operate independently at optimal low pressure.
3Loss of energy
If low-pressure steam is recompressed to medium pressure for heat transfer, then energy utilization efficiency improves, but device complexity increases
Solution Approach 1:
The invention makes the low-pressure vapor serve dual purposes: it is both the overhead product of the distillation column and the heat transfer medium after compression. The system uses its own vapor for heating requirements, reducing the need for external energy sources and justifying the added compression complexity through significant energy recovery.
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
Significantly reduces fuel and electricity consumption by effectively utilizing low-temperature heat, transforming it into a valuable energy source for reboiling and preheating, resulting in substantial energy gains within the aromatic complex.
Implementation Method 1
increasing its pressure by compression to transform it into medium-pressure steam
Implementation Method 2
using said medium-pressure steam, with or without intermediate compression, as a heat transfer fluid
Data Source
Figure 1a~1b
Figure 2
Figure 3
AI summary
The invention relates to a method for recovering available low-temperature heat in a process and to the use thereof for reducing the energy consumption of said process. The invention also relates to the application of the method to an aromatic complex wherein the low-temperature heat is recovered at the head of distillation columns in the form of low-pressure steam and reused for reboiling other distillation columns of which the operating pressure may have been lowered.