Titanium Dioxide Production via Multi-Stage Vapor Oxidation
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Solution Overview
Problem
Current processes for producing titanium dioxide pigments through gas phase oxidation are energy-intensive and result in undesired particle size growth and agglomeration, with inefficiencies in maintaining gaseous titanium tetrachloride feed and issues like unreacted titanium tetrahalide in the product, leading to high pressure drops and equipment damage.
Innovation Solution
A multi-stage vapor-phase oxidation process where a first portion of liquid titanium tetrahalide is vaporized and reacted with oxygen in the first stage, with additional liquid titanium tetrahalide introduced in subsequent stages to control particle size and distribution, avoiding substantial unreacted titanium tetrahalide and using the heat of vaporization for cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If liquid titanium tetrahalide is introduced in subsequent stages to control particle size, then particle size distribution is improved, but the complexity of the process increases
Solution Approach 1:
The oxidation process is divided into multiple stages: a first stage where gaseous titanium tetrahalide is oxidized, and subsequent stages where liquid titanium tetrahalide is introduced. This segmentation allows different feed forms to be used at different reaction stages, enabling precise control over particle size distribution while managing process complexity through structured multi-stage operation
Solution Approach 2:
The process changes the physical state parameter of titanium tetrahalide from gas in the first stage to liquid in subsequent stages. This parameter change allows the liquid feed to cool the reaction zone and control particle growth, thereby improving particle size distribution without requiring complete vaporization of all feed material
2Temperature
If liquid titanium tetrahalide is charged directly into subsequent stages, then cooling effect is achieved and particle size is controlled, but the risk of unreacted titanium tetrahalide in product increases
Solution Approach 1:
The process ensures continuous oxidation by maintaining sufficient oxygen-containing gas flow through all stages and ensuring complete reaction of liquid titanium tetrahalide before product discharge. This continuous useful action prevents unreacted titanium tetrahalide from accumulating in the final product, maintaining product purity despite the use of liquid feed in subsequent stages
Solution Approach 2:
Oxygen-containing gas acts as an intermediary that facilitates complete reaction of liquid titanium tetrahalide in subsequent stages. The sufficient supply of oxygen ensures that all liquid titanium tetrahalide is fully oxidized before the reaction product is discharged, preventing unreacted material from contaminating the final product
3Productivity
If gaseous titanium tetrahalide is used throughout, then reaction efficiency is high, but energy consumption increases due to continuous vaporization requirements
Solution Approach 1:
The process converts the potentially harmful effect of high energy consumption for continuous vaporization into a benefit by using liquid titanium tetrahalide in subsequent stages. The liquid feed provides a cooling effect that reduces the overall energy requirement for vaporization, while still maintaining high reaction efficiency through controlled oxidation of the liquid phase
Solution Approach 2:
The process utilizes phase transition of titanium tetrahalide from liquid to vapor only in the first stage, then introduces liquid directly in subsequent stages. This selective phase transition approach reduces the total energy required for vaporization while maintaining reaction efficiency, as the liquid feed in subsequent stages undergoes oxidation without requiring complete vaporization
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 achieves high conversion to titanium dioxide with improved particle size and distribution, reducing energy consumption and minimizing unreacted titanium tetrahalide, thus preventing equipment damage and enhancing product quality.
Implementation Method 1
vaporizing a first portion of the liquid titanium tetrahalide and reacting the titanium tetrahalide vapor and the oxygen-containing gas
Implementation Method 2
charging at least one additional portion of the liquid titanium tetrahalide directly into the at least one additional stage of the reaction zone to cool the titanium dioxide
Implementation Method 3
reacting the titanium tetrahalide vapor and the oxygen-containing gas, in a first stage of a reaction zone, the reaction zone temperature being sufficient to form a reaction product at least containing titanium dioxide
Data Source
AI summary
This disclosure relates to a process for producing titanium dioxide, comprising: a) providing a quantity of liquid titanium tetrahalide for reacting with an oxygen-containing gas; b) vaporizing a first portion of the liquid titanium tetrahalide and reacting the titanium tetrahalide vapor and the oxygen-containing gas, in a first stage of a reaction zone, the reaction zone temperature ranging from at least about 650°C to form a reaction product at least containing titanium dioxide and oxygen-containing gas and passing the reaction product, more typically in the vapor phase, to at least one additional stage of the reaction zone; and c) charging at least one additional portion of the liquid titanium tetrahalide to the at least one additional stage of the reaction zone to cool the titanium dioxide and to react with the oxygen-containing gas to form additional titanium dioxide. This process results in a high conversion to titanium dioxide and formation of titanium dioxide powders having improved particle size and size distribution.