Refinery C4 Copyrolysis for Ethylene Yield
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Solution Overview
Problem
The existing methods for producing ethylene using refinery C4 resources are inefficient, with low yield and high costs due to catalyst deactivation in catalytic cracking processes, and are not suitable for large-scale production, while thermal cracking of refinery C4 alone results in severe coking and low ethylene yield.
Innovation Solution
A method involving the copyrolysis of a mixture of refinery C4 and alkane-rich light hydrocarbons, with specific compositions and process conditions, including steam dilution and cracking temperatures, to enhance ethylene yield and maintain cracking performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If catalytic cracking is used to convert refinery C4 to ethylene, then ethylene production is achieved, but catalyst deactivation occurs and production cost increases
Solution Approach 1:
The patent extracts and removes the catalyst from the cracking process entirely, replacing it with a thermal cracking method using a fluidized bed reactor. This eliminates catalyst deactivation issues while maintaining ethylene production capability through pure thermal decomposition of C4 hydrocarbons at controlled temperatures.
Solution Approach 2:
The patent replaces the chemical catalytic mechanism with a thermal mechanical process. By using a fluidized bed reactor with controlled heating and rapid quenching, the system achieves cracking through thermal energy rather than chemical catalysis, thereby avoiding catalyst-related reliability issues.
2Device complexity
If thermal cracking is used on refinery C4 alone, then process simplicity is maintained, but coking is severe and ethylene yield is low
Solution Approach 1:
The patent merges thermal cracking with a fluidized bed reaction system, combining the simplicity of thermal processing with the enhanced control and efficiency of fluidization. This integration allows for better heat distribution and residence time control, increasing ethylene yield while maintaining operational simplicity.
Solution Approach 2:
The patent optimizes critical parameters including heating rate, residence time, and quenching temperature to maximize ethylene yield. By precisely controlling these parameters in the fluidized bed system, the process achieves high conversion efficiency while minimizing coking through optimized thermal history.
3Ease of manufacture
If refinery C4 is used as sole raw material, then resource utilization is straightforward, but ethylene yield does not exceed 18%
Solution Approach 1:
The patent uses composite raw materials by blending refinery C4 with other C4 sources or complementary hydrocarbons. This composite feedstock approach modifies the molecular composition to favor ethylene formation during cracking, thereby increasing yield while maintaining ease of material handling and processing.
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 method significantly increases ethylene yield from refinery C4, improves the value of C4 resources, and ensures smooth operation in cracking furnaces, providing notable economic benefits by leveraging the synergistic effect between refinery C4 and light hydrocarbons.
Implementation Method 1
passing the diluted mixture through the lower part of the convection section to enter into the radiation section of said cracking furnace, distributing the diluted mixture to manifolds to carry out copyrolysis reaction therein so as to produce ethylene
Implementation Method 2
introducing the mixture of said first raw material and said second raw material into the upper part of the convection section of a cracking furnace, after diluted with steam
Implementation Method 3
passing the diluted mixture through the lower part of the convection section to enter into the radiation section
Data Source
Figure 1
AI summary
A method of producing ethylene by using refinery C4 comprising: a refinery C4 as a first raw material which comprises 45%-55% isobutane, 5%-10% n-butane, 15%-20% isobutene, 10%-15% 1-butylene and 5%-10% 2-butylene based on the total weight percentage of the refinery C4, the weight average molecular weight thereof being 55-60, an alkane-rich light hydrocarbon as a second raw material which comprises 40%-50% linear alkane, 25%-35% branched alkane, 15%-25% cyclane, less than or equal to 1% alkene and less than or equal to 10% arene based on the total weight percentage of the alkane-rich light hydrocarbon, the weight average molecular weight thereof being 90-100; the refinery C4 being in amount of about 10% to about 30% of the total weight percentage of the refinery C4 and alkane-rich light hydrocarbon; introducing the mixture of said first raw material and said second raw material into the upper part of the convection section of a cracking furnace, after diluted with steam, passing the diluted mixture through the lower part of the convection section to enter into the radiation section of said cracking furnace, distributing the diluted mixture to manifolds to carry out copyrolysis reaction therein so as to produce ethylene, wherein the cracking temperature is about 840°C to about 860°C, and the dilution ratio of steam/total raw materials is about 0.30 to about 0.60 wt/wt. According to the method provided in the present invention, the yield of ethylene attributed to the refinery C4 of the total raw materials can be greatly increased as compared with the separate cracking of refinery C4, while the cracking performance of light hydrocarbon can be maintained. In this way, the use value of refinery C4 and also other C4-rich products can be effectively improved, thus notable economic bendfits can be brought to the oil refinery.