Two-Stage Oxy-Fired Gasification for CO2 Capture
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Solution Overview
Problem
Existing gasification processes face inefficiencies and high operational costs due to incomplete combustion and the need for energy-intensive amine separation units for carbon dioxide capture, particularly in the production of syngas from carbonaceous materials.
Innovation Solution
A two-stage, oxy-fired, non-catalytic gasification process with reactors operating at high temperatures and pressures, utilizing greater than 80% oxygen for combustion, which separates and recycles carbon dioxide, eliminating the need for amine separation units by producing a predominantly CO2 stream that can be easily sequestered.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If air-fired gasification is used, then nitrogen is present in the off-gas requiring complex separation, but oxygen-fired gasification produces a predominantly CO2 stream that is easier to capture
Solution Approach 1:
The patent changes the oxygen concentration parameter from typical air-fired conditions (21% O2) to oxygen-enriched conditions (>80% O2). This parameter change fundamentally alters the off-gas composition, producing a stream that is predominantly CO2 with minimal nitrogen, thereby eliminating the need for complex amine separation units and making CO2 capture straightforward.
Solution Approach 2:
The patent employs oxygen-enriched air (greater than 80% oxygen) as the oxidant instead of conventional air. This strong oxidant approach accelerates combustion and fundamentally changes the chemical reactions in the gasifier, resulting in complete combustion of carbon to CO2 and eliminating nitrogen from the off-gas stream, thus simplifying CO2 separation.
2Object-affected harmful factors
If amine separation units are used for CO2 capture, then CO2 can be removed, but the process becomes energy intensive and costly to operate
Solution Approach 1:
By changing the oxygen concentration parameter to >80% O2 in the gasification process, the off-gas composition is fundamentally altered to be predominantly CO2. This eliminates the need for energy-intensive amine separation units, as CO2 can be captured directly through simple cooling and condensation processes, dramatically reducing energy consumption.
Solution Approach 2:
The patent extracts nitrogen from the system by using oxygen-enriched air instead of conventional air. This extraction of the nitrogen component before combustion prevents its presence in the off-gas, thereby eliminating the need for subsequent nitrogen removal and CO2 separation processes, reducing both equipment complexity and energy consumption.
3Device complexity
If a single oxy-fired reactor is used, then equipment is simplified, but incomplete combustion results in inefficient process with substandard energy output
Solution Approach 1:
The patent divides the gasification process into two distinct stages: a first oxy-fired reactor for primary combustion and gasification, and a second oxy-fired reactor for completing combustion and producing high-purity CO2. This segmentation allows each reactor to be optimized for its specific function, achieving complete combustion and high energy efficiency while maintaining a relatively simple overall system configuration.
Solution Approach 2:
The two-stage oxy-fired system ensures continuous and complete combustion across both reactors. The first reactor initiates combustion and the second reactor completes it, ensuring that all carbon is converted to CO2 without incomplete combustion products. This continuous useful action maximizes energy output efficiency while using only oxygen-fired reactors, avoiding the need for additional separation equipment.
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 enhances carbon dioxide capture efficiency, reduces operational expenses, and simplifies equipment requirements, making it more cost-effective compared to conventional air-fired systems while maintaining high energy output.
Implementation Method 1
combusting in a first reaction zone a stream comprising an oxygen-containing gas and a first feedstock comprising of a slurry of particulate carbonaceous material
Implementation Method 2
carbon in the coal or coke can be converted into gas by partial combustion with oxygen, according to the following equations: C+O2→CO2 and C+1⁄2O2→CO
Implementation Method 3
recovering a second portion of the heat from said gaseous products stream of the second reaction product in a high temperature heat recovery system, including a fire-tube boiler, whereby the gaseous products are cooled to a temperature of about 450° F. to about 550° F.
Implementation Method 4
the gaseous products are cooled to a temperature of about 450° F. to about 550° F. (232° C. to 288.7° C.)
Data Source
AI summary
A process for gasification is provided for a non-catalytic, two-stage gasification process for gasification of a carbonaceous material. The reactor system generally comprises combustion in a first reaction zone and combustion in a second reaction zone.