Gasification Plant Reactor Design for Tar Reduction and Unloading
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Solution Overview
Problem
Existing gasification plants face issues with high levels of high-molecular-weight tars in synthesis gas, solid residue obstructions during unloading, air infiltration affecting combustion conditions, and leakage risks, leading to increased complexity and costs.
Innovation Solution
A gasification plant design with a reactor having specific zones for pyrolysis, combustion, reduction, and unloading, utilizing a low-porosity refractory material for the reactor body, air injectors creating a vortex for uniform combustion, and an unloading device with slits to prevent obstructions, along with a filter and heat exchange system to purify synthesis gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a conventional gasification plant design is used, then synthesis gas is produced, but high-molecular-weight tars are present in high quantities requiring complex removal systems
Solution Approach 1:
The patent applies parameter changes by modifying the reactor's physical and chemical parameters: using refractory material with porosity less than 10% (ideally 1-5%), maintaining specific temperature ranges in different zones (pyrolysis zone: 300-700°C, combustion zone: 800-1200°C), and controlling oxygen concentration (2-20% in combustion zone). These parameter optimizations reduce tar formation at the source, eliminating the need for complex external tar removal systems.
Solution Approach 2:
The patent extracts the harmful high-molecular-weight tars from the synthesis gas through the filter element (4) with porous structure, which physically separates and removes tars before the gas reaches the engine. This extraction principle directly addresses the tar problem without requiring complex additional processing equipment.
2Productivity
If solid residues with very small granulometry are unloaded, then combustion byproducts are removed, but obstructions occur in unloading devices requiring plant interruption
Solution Approach 1:
The patent applies dynamics by using a rotating shaft (38) with helical blades or flighting that continuously moves the solid residues from the bottom of the reactor through the refractory material layer to the discharge point. This dynamic mechanical action prevents residue accumulation and obstructions, enabling continuous operation without plant interruptions.
3Reliability
If air infiltration occurs from outside into the reactor, then combustion conditions are altered, but synthesis gas composition changes and combustion may propagate to the pyrolysis zone
Solution Approach 1:
The patent creates an inert atmosphere by using refractory material with very low porosity (less than 10%, ideally 1-5%) that acts as a barrier to air infiltration. This inert barrier prevents external air from entering the reactor zones, maintaining stable combustion conditions in the combustion zone and preventing combustion propagation to the pyrolysis zone where oxygen-free conditions are required.
4Reliability
If pressure reactor design is used, then synthesis gas is contained, but leakage of pyrolysis or synthesis gases to the outside is a risk
Solution Approach 1:
The refractory material with low porosity creates an inert barrier that prevents gas leakage to the outside while maintaining pressure containment. The dense refractory structure acts as both a thermal insulator and a gas barrier, eliminating leakage risks without compromising the pressure reactor's synthesis gas containment capability.
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 design significantly reduces tar content in synthesis gas, prevents obstructions during unloading, minimizes air infiltration, and ensures stable combustion, allowing for direct use of synthesis gas in internal combustion engines with high purity and reduced operational risks.
Implementation Method 1
utilizing a low-porosity refractory material for the reactor body, air injectors creating a vortex for uniform combustion
Implementation Method 2
air injectors creating a vortex for uniform combustion
Implementation Method 3
a first pyrolysis zone, in which the biomass introduced in the gasification apparatus is submitted to pyrolysis, that is a thermal decomposition which occurs exposing biomass at high temperatures
Implementation Method 4
a second combustion zone in which the biomass is subjected to a combustion process under oxygen shortage conditions
Implementation Method 5
a third reduction zone in which the combustible gas is produced, commonly referred to as syngas or synthetic gas
Implementation Method 6
This requires submitting the synthesis gas produced to a cracking process, for removing high-molecular-weight tars from gas
Data Source
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AI summary
A gasification plant (1) for producing combustible gas by pyrolysis and combustion of biomass comprises a reactor (2) supplied with said biomass, said reactor (2) comprises a reactor body (11) which is supplied with said biomass through a supply opening (7), said reactor body (7) comprising a first pyrolysis zone (12) in which said biomass is subjected to a pyrolysis treatment, a second combustion zone (13), in which the products of said pyrolysis treatment are subjected to combustion under oxygen shortage conditions, a third reduction zone (14) in which the combustion products are subjected to reduction and a fourth unloading zone (15) from which combustion solid residues and synthesis gas are discharged into a discharge conduit (19); said second combustion zone (13) comprises a truncated cone element (16), that narrows downwards to an outlet port (48) having a diameter D and communicating with said third reduction zone (14), which comprises a first truncated cone portion (17) followed by a cylindrical portion (18) having a diameter D1, a ratio between said second diameter D1 and said first diameter D being not lower than 2.5, a ratio between a volume V1 of said third reduction zone (14) and a volume V of said second combustion zone (13) being not lower than 3.5; said reactor body (11) is made of a very low porosity refractory material, such as to minimize air infiltrations from the outside into said reactor body (11) and an exit of vapours, gases and fumes from said reactor body (11) to the outside, through walls of said reactor body (11); said fourth unloading zone (15) comprises an unloading device (38) for solid materials that are residues of the combustion of biomass and of synthesis gas produced in the reactor (2), said unloading device (38) comprising an internally hollow body (39), the inside of which communicates with said discharge conduit (19), said body (39) being able to rotate around a longitudinal axis (B) of the reactor (2), said body (39) having a truncated cone shape or truncated pyramid shape on a side surface of which slits (40) are made.