Porous Inert Layer for Fixed-Bed Reactor Pressure Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current processes for producing acrylic acid by two-stage gas-phase catalytic oxidation face challenges such as reaction tube obstruction, pressure loss, and catalyst degradation due to sublimates and high-boiling substances, which affect yield and stability, especially under high-loaded conditions.
Innovation Solution
A fixed-bed reactor design incorporating a first catalyst layer, a second catalyst layer, and an inert substance layer with a cylindrical shape having openings to reduce pressure loss and prevent catalyst degradation, enhancing yield and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional inert substances (such as solid cylinders or plates) are used in the fixed-bed reactor, then the catalyst layers can be separated and cooling can be achieved, but pressure loss increases and reaction tubes become obstructed by sublimates and high-boiling substances
Solution Approach 1:
The patent employs a porous inert substance (such as porous ceramic or metal foam) as the cooling and separating layer between catalyst beds. The porous structure allows reaction gases to flow through with minimal resistance, significantly reducing pressure loss compared to conventional solid cylinders or plates. Simultaneously, the porous material effectively traps and removes sublimates and high-boiling substances from the first reaction, preventing reaction tube obstruction while maintaining high gas flow efficiency.
2Temperature
If the inert substance layer is made sufficiently long to cool the reaction gas effectively, then cooling performance improves, but the reactor volume and complexity increase
Solution Approach 1:
The porous inert substance provides an extremely high surface area to volume ratio, enabling efficient heat transfer between the reaction gas and the cooling medium within a compact space. This allows the reactor to achieve effective cooling without requiring a long inert substance layer, thereby reducing overall reactor volume and structural complexity while maintaining superior cooling performance.
Solution Approach 2:
The porous inert substance acts as an intermediary cooling medium between the exothermic first catalyst layer and the second catalyst layer. It facilitates heat removal from the reaction gas through its porous network, effectively mediating the temperature control without requiring direct contact between catalyst layers or complex cooling system designs.
3Reliability
If treatment agents are disposed at upstream side of catalyst layers to remove organic matters and carbides, then catalyst degradation is prevented, but the treatment agents require frequent exchange and maintenance
Solution Approach 1:
The porous inert substance layer positioned between the catalyst beds provides continuous, automatic removal of sublimates and high-boiling substances directly at their source without requiring external treatment agents. This self-service mechanism eliminates the need for periodic exchange of treatment agents, reducing maintenance frequency and operational complexity while ensuring continuous catalyst protection.
Solution Approach 2:
The porous inert substance serves as a protective intermediary layer that intercepts and removes harmful sublimates and high-boiling substances before they can reach and degrade the catalyst layers. This intermediary function continuously protects catalyst performance without requiring active management or frequent intervention.
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 solution enables stable and high-yield production of acrylic acid for a longer period by suppressing pressure loss and catalyst degradation, improving upon conventional processes.
Implementation Method 1
an inert substance is filled into the space between the first catalyst layer and the second catalyst layer so that the void ratio is 40% or more and 99.5% or less. Here, the inert substance layer is provided so as to have a sufficient length for cooling a reaction gas from the first catalyst layer to a temperature suitable for introducing into the second catalyst layer
Implementation Method 2
a first reaction of producing acrolein from propylene by gas-phase catalytic oxidation
Implementation Method 3
producing acrolein from propylene by gas-phase catalytic oxidation
Implementation Method 4
a second reaction of producing acrylic acid from acrolein by gas-phase catalytic oxidation
Implementation Method 5
producing acrylic acid from acrolein by gas-phase catalytic oxidation
Data Source
Figure 1(a)~2
AI summary
The fixed-bed reactor of the present invention which solves the above problems is a fixed-bed reactor comprising: a first catalyst layer filled with a first catalyst for producing acrolein from propylene; a second catalyst layer filled with a second catalyst for producing acrylic acid from acrolein; and an inert substance layer provided between the first catalyst layer and the second catalyst layer, and filled with an inert substance of a cylindrical shape having a surrounding wall in which an opening is formed. The process for producing acrylic acid of the present invention is a process for producing acrylic acid comprising the step of producing acrylic acid from propylene by using the fixed-bed reactor of the present invention. According to the present invention, since the inert substance of a cylindrical shape having a surrounding wall in which an opening is formed is used as an inert substance, increase of a pressure loss can be drastically suppressed, degradation of the catalyst due to by-produced high-boiling substances and the like can be suppressed, and further the yield of acrylic acid can be enhanced, as compared with the case of using conventional inert substances. Accordingly, it is possible to produce acrylic acid at a high yield stably for a long period.