Biomass Gasification via Two-Step Oxidation to Prevent Agglomeration
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Solution Overview
Problem
Existing methods for producing synthesis gas from biomass face challenges due to impurities like ammonia, sulfur compounds, and inorganic materials that lead to catalyst poisoning and agglomeration, resulting in high capital and operating costs and inefficient gasification processes.
Innovation Solution
A two-step process involving the initial contact of biomass with an oxidizing gas containing oxygen and steam to heat it between 500°C and 750°C, followed by further treatment with oxygen and steam to reach 800°C to 850°C, effectively producing synthesis gas while minimizing impurities and agglomeration through the use of additives like calcium oxide to neutralize chlorine and sulfur, and operating in a fluidized bed with a freeboard section to maintain plug flow and reduce deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If biomass is gasified at high temperatures (1200°C or above) to produce synthesis gas, then the synthesis gas can be produced efficiently, but inorganic materials melt and cause agglomeration and deposits
Solution Approach 1:
The patent changes the temperature parameter from conventional high-temperature gasification (1200°C or above) to a lower temperature range (800°C to 850°C). This parameter change prevents inorganic materials from melting while still achieving effective synthesis gas production through a two-step process involving partial oxidation followed by gasification
Solution Approach 2:
The patent introduces an intermediary step of partial oxidation at lower temperature before the main gasification process. This intermediary step converts part of the biomass to combustible gases and heat, which then facilitate the subsequent gasification at controlled temperatures, avoiding direct high-temperature processing that causes inorganic material melting
2Productivity
If crude synthesis gas is produced from biomass gasification, then synthesis gas is obtained, but impurities like ammonia, sulfur compounds, and tars cause catalyst poisoning
Solution Approach 1:
The patent performs preliminary action by conducting partial oxidation of biomass before the main gasification process. This preliminary step converts part of the biomass to combustible substances and generates heat, which facilitates the subsequent gasification process and helps control impurity formation from the outset
Solution Approach 2:
The patent changes the operational parameters by maintaining controlled temperature ranges (800°C to 850°C) and using a two-step process with partial oxidation followed by gasification. These parameter changes reduce the formation of harmful impurities like tars and sulfur compounds that would otherwise poison catalysts in downstream applications
3Productivity
If conventional gasification processes are used to produce synthesis gas, then synthesis gas is obtained, but capital and operating costs are high due to impurity removal requirements
Solution Approach 1:
The patent changes the temperature parameter to a lower range (800°C to 850°C) compared to conventional high-temperature gasification (1200°C or above). This parameter change reduces energy consumption and equipment requirements, thereby lowering both capital and operating costs while still achieving effective synthesis gas production
Solution Approach 2:
The patent introduces preliminary partial oxidation as a preparatory step that converts part of the biomass to combustible gases and heat. This preliminary action reduces the overall energy input required for the main gasification process and minimizes impurity formation, leading to reduced costs for impurity removal equipment and operations
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 process efficiently produces purified synthesis gas with reduced impurities, enabling its use as a fuel or for synthesizing products like methanol and ethanol, while minimizing capital and operating costs by preventing catalyst poisoning and agglomeration.
Implementation Method 1
contacting biomass, in a first step, with oxygen and steam, wherein the oxygen is present in an amount effective to oxidize the biomass, thereby producing heat sufficient to heat the biomass to a temperature of at least 500°C and no greater than 750°C
Implementation Method 2
oxidize the biomass, thereby producing heat sufficient to heat the biomass
Implementation Method 3
at least a portion of the oxidized biomass produced in the first step is treated with oxygen and steam to heat the biomass to a temperature of at least 800°C and which does not exceed 850°C, thereby producing synthesis gas
Implementation Method 4
use of additives like calcium oxide to neutralize chlorine and sulfur
Data Source
Figure 1
AI summary
A process for producing synthesis gas from biomass in which biomass is contacted with oxygen and steam, wherein the oxygen is present in an amount effective to oxidize the biomass partially and to heat the biomass to a temperature of at least 500°C and no greater than 750°C At least a portion of the partially oxidized biomass then is treated with oxygen and steam to heat the biomass to a temperature of at least 800°C, thereby producing a synthesis gas, which then is recovered