Fluidized Catalyst Startup Heating Using Hydrogen Combustion
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Solution Overview
Problem
Existing fluidized reactor systems face inefficiencies in heating catalysts to operating temperatures during reactor startup due to low methane combustion rates at temperatures below 650°C, leading to heat loss and the need for costly fuel oil systems.
Innovation Solution
Utilizing a commencement fuel gas stream comprising at least 80 mol% of hydrogen or other gases like ethylene, which catalytically combusts at high efficiency (greater than 50%) at temperatures below 500°C, heating the catalyst to the operating temperature range without the need for fuel oil systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If methane is used as fuel source for heating catalyst during reactor startup, then operating temperature can be maintained, but combustion efficiency is low at temperatures below 650°C leading to heat loss
Solution Approach 1:
The patent introduces a preliminary heating phase using a different fuel (propane or hydrogen) before introducing methane combustion. This preliminary action raises the catalyst temperature to a level where methane combustion becomes efficient, preventing the energy loss that would occur if methane were used alone at lower temperatures.
Solution Approach 2:
The patent uses an intermediary fuel (propane or hydrogen) that can combust efficiently at lower temperatures to bridge the gap during startup. This intermediary fuel performs the heating function initially, then is replaced by methane combustion once temperatures are sufficient, avoiding the inefficiency of direct methane combustion at low temperatures.
2Temperature
If fuel oil system is used to heat catalyst during startup, then catalyst reaches operating temperature, but capital costs increase due to specialized equipment requirements
Solution Approach 1:
The patent makes the combustor self-sufficient by using the catalyst itself as the heating medium. The catalyst circulates through the combustor and absorbs heat from the burning fuel, then returns to the reactor to provide heat for the endothermic reaction. This eliminates the need for external fuel oil systems and associated complex equipment.
Solution Approach 2:
The catalyst serves multiple functions: it acts as both the reaction catalyst in the reactor and the heat transfer medium in the combustor. This multi-functionality eliminates the need for separate heating systems, reducing device complexity while maintaining the ability to reach and maintain operating temperatures.
3Loss of energy
If catalyst is heated to high temperature immediately during startup, then combustion efficiency improves, but energy consumption increases due to heat loss
Solution Approach 1:
The patent implements a periodic heating strategy where fuel is introduced in stages. First, a preliminary fuel heats the catalyst to intermediate temperatures, then methane is introduced for final heating. This periodic approach maintains high combustion efficiency at each stage while minimizing total energy consumption by avoiding excessive heating.
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 method efficiently heats the catalyst to the required operating temperature, reducing capital costs by eliminating the need for specialized fuel oil equipment and enhancing energy efficiency.
Implementation Method 1
contacting the catalyst at the first temperature with a commencement fuel gas stream comprises at least 80 mol% of a commencement fuel gas in the catalyst processing portion, wherein the contacting of the catalyst with the commencement fuel gas stream causes combustion of the commencement fuel gas
Data Source
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AI summary
A process for commencing a continuous reaction in a reactor system includes introducing a catalyst to a catalyst processing portion of the reactor system, the catalyst initially having a first temperature of 500 C or less, and contacting the catalyst at the first temperature with a commencement fuel gas stream, which includes at least 80 mol% commencement fuel gas, in the catalyst processing portion. Contacting of the catalyst with the commencement fuel gas stream causes combustion of the commencement fuel gas. The process includes maintaining the contacting of the catalyst with the commencement fuel gas stream until the temperature of the catalyst increases from the first temperature to a second temperature at which combustion of a regenerator fuel source maintains an operating temperature range in the catalyst processing portion.