Methane Removal Catalyst with Heat Recovery
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Solution Overview
Problem
Current methods for removing low-concentration methane from coal mine ventilation gas are inefficient due to high temperatures required, catalyst poisoning by sulfur compounds, and variability in methane concentration, leading to poor economic performance and catalyst deterioration.
Innovation Solution
A method involving a heat exchanger and an oxidization catalyst with iridium and platinum supported on zirconia or titania, where the gas flow rate to the catalyst is adjusted based on methane concentration to maintain optimal temperatures, preventing catalyst deterioration and improving economic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional catalysts (Pt or Pd supported on aluminum support) are used for catalytic oxidization, then oxidization of easily oxidized compounds (toluene, acetone, ethyl acetate) can be achieved at low temperatures of 350°C or lower, but oxidization removal of methane is difficult at low temperatures of 400°C or lower
Solution Approach 1:
The patent changes the chemical parameters of the catalyst system by selecting specific metal combinations (Ir-Pt or Rh-Pt) and support materials (ceria-zirconia mixed oxide or titania) to achieve methane oxidization at lower temperatures. This parameter change in catalyst composition enables the system to overcome the inherent stability of methane and achieve effective removal at temperatures where conventional catalysts fail.
2Reliability
If the catalyst inlet temperature is increased to 500°C or higher to achieve satisfactory methane removal performance, then methane removal performance is improved, but the catalyst outlet temperature becomes from 600°C to 700°C which is detrimental to catalyst durability and requires additional heat resistant piping and heat exchanger
Solution Approach 1:
The patent changes the thermal parameters of the system by optimizing the catalyst's activity to achieve high methane removal performance at lower operating temperatures. The novel catalyst composition enables the reaction to proceed efficiently at inlet temperatures around 350-450°C, producing outlet temperatures in the range of 450-550°C, thus avoiding the need for expensive heat-resistant materials and reducing thermal stress on the system.
Solution Approach 2:
The patent employs composite material structures including Ir-Pt or Rh-Pt bimetallic catalysts supported on ceria-zirconia mixed oxide or titania. These composite materials provide enhanced catalytic activity and thermal stability, enabling effective methane removal at moderate temperatures while maintaining catalyst durability and avoiding excessive outlet temperatures that would require additional heat-resistant infrastructure.
3Quantity of substance
If a heat exchanger with large capacity is used to preheat coal mine ventilation gas at ambient temperature, then preheating of large amount of gas is achieved, but economic performance becomes inferior
Solution Approach 1:
The patent changes the thermal efficiency parameter of the system by utilizing the exothermic heat of methane oxidization reaction. The reactor is designed to recover and reuse the reaction heat for preheating the incoming gas stream, thereby reducing or eliminating the need for external large-capacity heat exchangers and associated capital costs, while still achieving effective preheating of large volumes of ventilation gas.
4Reliability
If sulfur compounds are present in coal mine ventilation gas, then catalyst poisoning occurs which makes catalytic oxidization of methane even more difficult, but the patent achieves satisfactory methane removal performance even in the coexistence of sulfur compound
Solution Approach 1:
The patent employs composite material structures including Ir-Pt or Rh-Pt bimetallic catalysts supported on ceria-zirconia mixed oxide or titania. These composite materials provide enhanced resistance to sulfur compound poisoning while maintaining high catalytic activity for methane oxidization. The unique composition and structure of these composite catalysts enable them to withstand the presence of sulfur compounds in coal mine ventilation gas without significant performance degradation.
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
This approach allows for stable and efficient methane removal at low temperatures, even in the presence of sulfur compounds, with reduced heat exchanger capacity needs and extended catalyst life, contributing to cost savings and environmental benefits.
Implementation Method 1
feeding the treatment-object gas through a heat exchanger for preheating the treatment-object gas
Implementation Method 2
feeding the resultant gas to an oxidization catalyst to contact-oxidize methane
Implementation Method 3
contact-oxidizing methane for a catalytic oxidization reaction
Implementation Method 4
feeding the resultant reacted gas again through the heat exchanger together with an amount of un-reacted gas for recovery of heat from the reacted gas through heat exchange with the un-reacted gas
Data Source
AI summary
Disclosed are a method and an apparatus for removing methane from a gas which contains the methane at such a low concentration as not to be rendered into a combustible range with whatever ratio of air mixed therewith. In order to ensure satisfactory methane removal performance even in the coexistence of sulfur compound and in order also to provide stable methane removal performance for an extended period of time without performance deterioration even when the methane concentration varies significantly, the gas is fed to a heat exchanger for preheating and methane is exposed to an oxidation catalyst which oxidizes the methane through contact therewith. Then, the resultant gas is fed again to the heat exchanger for heat recovery through heat exchange with un-reacted gas. Further, the flow rate of gas to be treated is varied, according to a concentration of the methane contained in this treated gas.