Zirconia Refractory Lining for Low-Volatilization Combustion Chambers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing refractory materials, particularly high alumina refractories, suffer from volatilization of aluminum oxide (Al2O3) in combustion chambers of gasification plants operating at high temperatures and pressures, leading to material loss, equipment fouling, and operational inefficiencies.
Innovation Solution
A zirconia-based refractory lining with a minimum 20 wt.% tetragonal and cubic ZrO2 content, stabilized with calcium oxide, magnesium oxide, or yttrium oxide, is used to form a coating or thick lining that resists volatilization, with a silica content below 2.0 wt.%, applied through a multi-step in situ process at high temperatures and pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high alumina refractories are used for the inner wall layer, then thermal insulation is provided and structural integrity is maintained, but Al2O3 volatilization occurs leading to material loss and equipment fouling
Solution Approach 1:
The patent applies composite materials by combining zirconia (ZrO2) with alumina (Al2O3) in a specific ratio (30-70 wt% ZrO2 and 70-30 wt% Al2O3). The zirconia component provides resistance to Al2O3 volatilization while the alumina maintains structural integrity and thermal insulation properties. This composite approach resolves the contradiction by integrating two materials with complementary functions.
Solution Approach 2:
The patent changes the chemical composition parameters of the refractory material by introducing zirconia as a key additive and controlling the Al2O3 content within specific ranges. By adjusting these compositional parameters, the material achieves both resistance to volatilization and maintenance of structural integrity under high-temperature conditions.
2Strength
If high alumina refractories are used, then material strength is maintained, but material loss occurs due to volatilization at high temperatures
Solution Approach 1:
The composite refractory material combines zirconia and alumina where zirconia enhances resistance to thermal degradation and volatilization, thereby extending service life, while alumina provides the necessary mechanical strength. The synergistic effect of this composite system addresses both strength requirements and durability against high-temperature degradation.
Solution Approach 2:
The patent develops a refractory lining that can be applied as a coating or thin layer on the inner wall, reducing the need for thick, heavy traditional refractories. This approach allows for easier replacement and maintenance while extending the effective service life through improved resistance to volatilization and thermal degradation.
3Ease of manufacture
If traditional refractory linings are used, then installation is straightforward, but frequent maintenance is required due to material loss and fouling
Solution Approach 1:
The composite zirconia-alumina refractory material is formulated to provide long-lasting performance that reduces maintenance frequency. The material can be applied as a coating or castable lining that maintains its properties under severe operating conditions, thereby extending operational cycles between maintenance activities and improving overall productivity.
Solution Approach 2:
The patent aims to enable continuous operation of the industrial furnace by providing a refractory lining that resists degradation and prevents fouling. The zirconia-alumina composite maintains its integrity and protective function over extended periods, allowing the production process to continue without interruption for maintenance or cleaning.
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 zirconia lining significantly reduces Al2O3 volatilization, maintaining structural integrity and improving thermal insulation, reducing material loss by up to 85%, and preventing equipment fouling in reducing atmospheres.
Implementation Method 1
The zirconia lining significantly reduces Al2O3 volatilization, maintaining structural integrity and improving thermal insulation, reducing material loss by up to 85%, and preventing equipment fouling in reducing atmospheres.
Implementation Method 2
The zirconia lining significantly reduces Al2O3 volatilization, maintaining structural integrity and improving thermal insulation
Implementation Method 3
ZrO2 appears in form of monoclinic (m), tetragonal (t) and cubic (c) crystal modifications. The transformation from monoclinic to tetragonal and back takes place at approx. 1150° C. on heating and at approx. 800° C. on cooling.
Implementation Method 4
This temperature-dependent transformation would induce large stresses and consequently a critical crack formation at temperature changes
Implementation Method 5
For thick refractory members such as 20 mm-250 mm are the firing temperatures above 1400° C., preferably above 1600° C.
Data Source
AI summary
A refractory lining in a combustion chamber operating in a reducing atmosphere. The lining includes at least one or more Zirconia (Zr)-based refractory lining members comprising one or more Zr-based parts. The Zr-based parts comprise at least 90 wt. %, preferably at least 95 wt. %, of monoclinic ZrO2 and/or partially stabilized ZrO2 and/or fully stabilized ZrO2, wherein the total content of tetragonal and cubic ZrO2 amounts to at least 20 wt. %, preferably more than 35 wt. %, as well as Zr based refractory lining members and methods for manufacturing the Zr based refractory lining members.