Heavy Ends Column Feed Preheating via Waste Heat Recovery
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Solution Overview
Problem
Current processes for manufacturing ethylene dichloride (EDC) in vinyl chloride monomer production lack effective energy-saving methods, particularly in the heavy ends column, which is a critical area for thermal duty reduction.
Innovation Solution
The process involves heating the feed to the heavy ends column using waste heat from the EDC manufacturing process, specifically utilizing vapor recompression devices to generate heat for a falling film heat exchanger, thereby reducing the thermal duty of the reboiler and enhancing energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the heavy ends column is used to purify EDC by removing heavy impurities, then purification quality is improved, but thermal duty and energy consumption increase
Solution Approach 1:
The feed to the heavy ends column is preheated using waste heat from the EDC manufacturing process before entering the column. This preliminary heating action reduces the thermal duty required by the reboiler, thereby lowering energy consumption while maintaining the column's purification function.
Solution Approach 2:
Waste heat that would otherwise be discarded from the EDC manufacturing process is recovered and utilized to preheat the feed stream. This converts a harmful waste resource into a beneficial heating source, reducing the energy burden on the reboiler and improving overall process efficiency.
2Use of energy by moving object
If waste heat recovery is implemented to reduce energy consumption, then energy efficiency is improved, but device complexity increases
Solution Approach 1:
The waste heat recovery system is integrated with the existing EDC manufacturing process by using the same process streams for both EDC production and heat supply. The feed preheating function is merged with the waste heat availability, combining two process functions into a unified system that reduces energy consumption without requiring entirely separate equipment.
3Use of energy by moving object
If vapor recompression is used to generate heat for the falling film heat exchanger, then energy savings are improved, but mechanical power consumption increases
Solution Approach 1:
Vapor recompression utilizes phase transition of the working fluid (evaporation and condensation) to transfer heat from the waste heat source to the feed stream. The phase change process enables efficient heat transfer at constant temperature, allowing the falling film heat exchanger to preheat the feed effectively while the recompression system recovers energy from the vapor phase.
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 leads to significant energy savings, with embodiments showing up to 27.1% boiler savings and reduced cooling capacity, while also avoiding additional mechanical power consumption in some configurations.
Implementation Method 1
heating the feed to the heavy ends column using waste heat from the EDC manufacturing process, specifically utilizing vapor recompression devices to generate heat for a falling film heat exchanger
Implementation Method 2
utilizing vapor recompression devices to generate heat for a falling film heat exchanger
Data Source
AI summary
Process for the manufacture of EDC or Ethylene Di-Chloride by chlorination and/or oxychlorination of ethylene, said process comprising the purification of an EDC stream according to the following steps : - eventually removing the lower boiling impurities from the EDC stream so as to generate a stream of EDC substantially free from lower boiling impurities; - feeding this EDC stream to a heavy ends distillation column so as to get a top stream of substantially pure EDC and a bottom stream comprising higher boiling impurities and EDC, wherein the EDC stream fed to the heavy ends distillation column is at least partly heated up by a heater using waste heat available in the EDC manufacturing process itself or in a subsequent pyrolysis step of said EDC into vinyl chloride monomer or VCM or in an oxychlorination unit of ethylene to EDC.