Ethane Chlorination Process for Vinyl Chloride Production
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Solution Overview
Problem
Conventional methods for producing hydrogen chloride, ethylene, and vinyl chloride from ethane are inefficient and costly due to the high expense of ethylene, which requires complex high-temperature cracking processes, and previous chlorinating agents like C2Cl6 incur additional operating and capital costs or result in low selectivity to desired products.
Innovation Solution
A continuous, nearly adiabatic process involving a molar ratio of chlorine to ethane between 1.1 and 1.9 in a reaction zone to produce crude products, followed by fractional separation and partial recycling of hydrogen chloride and ethylene, achieving high selectivity and yield of vinyl chloride monomer and ethylene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ethylene is used as feedstock for chlorinated hydrocarbons, then product quality is maintained, but raw material cost increases due to expensive ethylene production requiring complex high-temperature cracking processes
Solution Approach 1:
The invention changes the feedstock parameter from ethylene to ethane, and adjusts the chlorination conditions (temperature 200-400°C, chlorine to ethane molar ratio 0.5-2.0) to achieve efficient conversion. This parameter change eliminates the need for complex high-temperature cracking processes while maintaining product quality and reducing raw material costs.
2Productivity
If C2Cl6 is used as chlorinating agent, then chlorination reaction proceeds, but additional operating and capital costs are incurred for producing and purifying C2Cl6
Solution Approach 1:
The invention extracts C2Cl6 from the system by using chlorine gas directly as the chlorinating agent instead of requiring C2Cl6 as an intermediate. This eliminates the need for oxychlorination reactors, separation columns, and purification systems, thereby reducing both operating and capital costs while maintaining reaction efficiency.
3Speed
If high chlorine to ethane molar ratio is used for chlorination, then reaction rate increases, but selectivity to desired products decreases leading to more byproducts
Solution Approach 1:
The invention applies dynamic control of the chlorine to ethane molar ratio, adjusting it within the range of 0.5-2.0 based on process conditions. Combined with temperature control (200-400°C) and the use of adiabatic or semi-adiabatic reactors, this dynamic approach optimizes both reaction rate and selectivity, achieving high conversion efficiency with minimal byproducts.
4Productivity
If conventional chlorination processes are used, then hydrogen chloride and ethylene are produced, but separation and purification require additional equipment and operational complexity
Solution Approach 1:
The invention merges the chlorination reaction with in-situ product separation by utilizing the physical properties of products formed. The reaction conditions and reactor design facilitate direct separation of HCl gas from the liquid phase products, eliminating or reducing the need for separate purification equipment and simplifying the overall process.
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
The process achieves high efficiency with greater than 95% chlorine conversion and ethane conversion of over 90%, resulting in a higher yield of vinyl chloride and ethylene, reducing raw material costs and operational expenses compared to traditional methods.
Implementation Method 1
reacting a feed comprising chlorine with ethane, wherein the molar ratio of chlorine to ethane in the feed is from 1.1 to 1.9, in a reaction zone to produce a crude product wherein the crude product comprises i. product components comprising hydrogen chloride, ethylene, and vinyl chloride monomer
Implementation Method 2
As used herein 'adiabatic' means: the thermal chlorination process or reaction occurs without transfer of heat between the reactor and its surroundings. The process is said to be nearly adiabatic because the reactor is insulated or designed in such a manner that heat is not intentionally added or removed from the reactor.
Implementation Method 3
fractionally separating from the crude product the partial recycle ; and c) fractionally separating from the crude product the product components
Data Source
Figure 1
AI summary
A process is provided for the chlorination of ethane using chlorine as the chlorinating agent to produce ethylene, hydrogen chloride (HCl) and vinyl chloride monomer (VCM).