Heavy Feed Mixer Vaporization Design
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Solution Overview
Problem
The production of olefins from heavy hydrocarbon feedstocks in pyrolysis furnaces is hindered by fouling and coking issues due to incomplete vaporization of heavy hydrocarbon feedstocks, leading to increased costs and reduced efficiency, as existing solutions either require additional processing steps, complex piping, or lengthy vaporization processes.
Innovation Solution
A compact apparatus with a converging/diverging tubular section and counter-current steam flow design that efficiently vaporizes heavy hydrocarbon feedstocks with steam, minimizing coke formation and reducing capital and operating costs by achieving complete vaporization within a shorter length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If heavy hydrocarbon feedstock is fed to a pyrolysis furnace for olefin production, then olefins can be produced from lower-cost feedstocks, but fouling and coking occur in the convection section tubes due to incomplete vaporization
Solution Approach 1:
The patent applies preliminary action by completely vaporizing the heavy hydrocarbon feedstock with steam in the convection section before the mixture enters the radiant section for cracking. This preliminary vaporization prevents heavy ends from condensing and causing coking in the convection section tubes, thereby enabling continuous operation and olefin production from heavy feedstocks without the harmful fouling effects.
2Object-affected harmful factors
If heavy hydrocarbon feedstock is completely vaporized with steam in the convection section, then fouling and coking are prevented, but the required vaporization length becomes excessively long
Solution Approach 1:
The patent applies parameter changes by introducing superheated steam at high temperature into the convection section to dramatically increase the vaporization rate of heavy hydrocarbon feedstock. This parameter change (using superheated steam instead of normal steam) enables complete vaporization to occur within a short distance, preventing coking while avoiding the need for an excessively long vaporization section.
Solution Approach 2:
The patent applies another dimension by utilizing the temperature dimension through superheated steam. Instead of relying solely on the length dimension for vaporization, the invention introduces a temperature parameter (superheated steam at high temperature) that accelerates the vaporization process, allowing complete vaporization to occur in a compact space rather than requiring a long vaporization section.
3Device complexity
If conventional piping and mixing equipment are used to vaporize heavy feedstock, then the process is simple, but complete vaporization cannot be achieved without excessive length or additional processing steps
Solution Approach 1:
The patent applies merging by combining the vaporization function directly into the convection section of the existing pyrolysis furnace. Instead of using separate mixing and vaporization equipment, the invention integrates steam injection and vaporization into the convection section's existing structure, maintaining process simplicity while achieving complete vaporization through the use of superheated steam and strategic injection positioning.
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 apparatus effectively prevents coking and fouling by ensuring complete vaporization of heavy hydrocarbon feedstocks, enhancing mixing efficiency, and reducing the length and costs associated with vaporization, thereby improving the production of olefins in pyrolysis furnaces.
Implementation Method 1
a source of superheated dilution steam... the steam and the preheated heavy hydrocarbon feed are mixed together to completely vaporize the liquid feed
Implementation Method 2
the steam and the preheated heavy hydrocarbon feed are mixed together in a vaporization zone within the converging section
Implementation Method 3
The preheated feed is then directed to a radiant section, wherein the feedstock-steam mixture is heated with radiant heat
Implementation Method 4
Thermal cracking to convert hydrocarbon feedstocks into more useful gaseous and liquid by-products is a well known process. The cracking process, which is also known as pyrolysis, cracks the carbon-carbon bonds in longer hydrocarbons to form smaller chain hydrocarbons.
Data Source
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AI summary
An apparatus designed to completely vaporize an intake of heavy hydrocarbon feedstock is described. The apparatus, a so-called heavy feed mixer, is comprised of pipes being disposed coaxially about a common longitudinal axis. The inner tubular section delivers a two-phase liquid-vapor mixture of hydrocarbon feedstock and dilution steam to the apparatus. The converging/diverging tubular section has a unique structure which converges to a throat section and then diverges to an outlet section. The converging section directs a uniform shroud of superheated steam onto the hydrocarbon stream delivered by the inner tubular section. Impingement of the superheated steam with the intake stream initiates mixing and further vaporization within the throat section. The mixture traverses the converging/diverging tubular section and passes into the outlet section where vaporization is complete. The completely vaporized stream is directed out of the apparatus for further processing downstream.