Steam Cracking Sulfur Additive Control for Low Carbon Disulfide
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Solution Overview
Problem
Conventional steam cracking processes for producing olefins produce carbon disulfide and other sulfur-containing impurities, leading to out-of-specification product streams and downstream process issues.
Innovation Solution
Introduce hydrogen sulfide gas to replace organosulfur compounds in the hydrocarbon cracking unit, reducing the formation of carbon disulfide and other sulfur impurities by maintaining a molar concentration of elemental sulfur between 10 ppm to 200 ppm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If organosulfur compounds are introduced to passivate internal coil surfaces and reduce coke formation, then coil lifetime is improved, but carbon disulfide and sulfur impurities are generated causing product specification failures
Solution Approach 1:
The patent changes the chemical form of sulfur from organosulfur compounds to inorganic sulfur compounds (H2S, SO2, COS), fundamentally altering the chemical parameters of the passivation agent to eliminate carbon disulfide formation while maintaining coke reduction effectiveness
Solution Approach 2:
The patent employs easily handled liquid organosulfur compounds like DMDS that decompose to provide sulfur for passivation, replacing them with gaseous inorganic sulfur compounds that achieve the same passivation effect without generating harmful carbon-containing sulfur impurities
2Quantity of substance
If organosulfur compounds are added to control carbon monoxide concentration, then CO concentration is improved, but sulfur impurities are produced affecting downstream processes
Solution Approach 1:
The patent changes the sulfur source from organic to inorganic compounds, altering the decomposition products to eliminate carbon-containing sulfur impurities while maintaining the ability to control CO concentration through sulfur-mediated reactions
3Loss of substance
If dimethyl disulfide is used to reduce coke formation, then coke deposition is reduced, but product streams become out-of-specification due to sulfur impurities
Solution Approach 1:
The patent fundamentally changes the chemical composition parameter of the sulfur compound from organic (DMDS) to inorganic (H2S, SO2, COS), eliminating the carbon source that leads to carbon disulfide formation and thereby ensuring product specification compliance while maintaining coke reduction
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
Reduces carbon disulfide concentration in pygas streams to less than 50 ppmw, preventing out-of-specification product streams and improving downstream process operation.
Implementation Method 1
organosulfur compounds, such as DMDS, undergo decomposition under the reaction conditions in the hydrocarbon cracking unit. The decomposition of these organosulfur compounds at the reaction conditions in the hydrocarbon cracking unit produces sulfur impurities, such as but not limited to carbon disulfide and methyl mercaptan
Implementation Method 2
sulfur in the form of organosulfur compounds, such as dimethyl disulfide (DMDS), dimethyl sulfide (DMS), diethyl disulfide (DEDS), diethyl sulfide (DES), methyl mercaptan (MM), or combinations thereof, are often introduced to the steam cracking unit to passivate the internal coil surface to reduce coke formation on the internal furnace coils
Data Source
AI summary
Methods for producing olefins through hydrocarbon steam cracking include passing a hydrocarbon feed that includes one or more hydrocarbons to a hydrocarbon cracking unit and passing one or more sulfur-containing compounds to the hydrocarbon cracking unit. The sulfur-containing compounds include at least hydrogen sulfide gas, and a flow rate of the sulfur-containing compounds to the hydrocarbon cracking unit is sufficient to produce a molar concentration of elemental sulfur in the hydrocarbon cracking unit of from 10 ppm to 200 ppm. The methods include cracking the hydrocarbon feed in the hydrocarbon cracking unit to produce a cracker effluent and contacting the cracker effluent with a quench fluid in a quench unit to produce at least a cracked gas and a first pygas. The first pygas has a concentration of carbon disulfide less than 50 ppmw based on the total mass flow rate of the first pygas.