Residence Time Device for Pollutant Conversion in Calciner
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Solution Overview
Problem
Existing exhaust gas treatment processes for pollutants, especially from alternative fuels, require reheating to achieve conversion temperatures above 800 °C, leading to energy consumption and additional heat exchangers, and fail to effectively convert pollutants at lower calcinator temperatures.
Innovation Solution
A device comprising a preheater, calciner, material cooler, and a residence time device with a combustion chamber positioned outside the solids stream, allowing separate treatment of exhaust gases at optimal temperatures, using an auxiliary combustion device and reaction agents to convert pollutants like NOₓ and CₓH₅ efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If exhaust gas treatment is performed using conventional methods with downstream treatment devices, then pollutant conversion can be achieved, but additional energy consumption is required for reheating exhaust gases to temperatures above 800 °C
Solution Approach 1:
The invention merges the exhaust gas treatment function with the existing calciner by routing exhaust gases through the combustion chamber where they are heated to conversion temperatures. This integration eliminates the need for separate downstream treatment devices and their associated reheating energy requirements, as the calciner's combustion process naturally provides the necessary thermal conditions for pollutant conversion.
Solution Approach 2:
The system uses its own combustion process to treat its own exhaust gases. The combustion chamber, which generates heat for the calcination process, simultaneously serves to heat and treat the exhaust gases by routing them through the same chamber, enabling self-service exhaust gas treatment without external energy input.
2Object-generated harmful factors
If alternative fuels are used to replace pulverized coal, then climate neutrality is improved, but ignition difficulty increases and minimum burning times and temperatures must be met
Solution Approach 1:
The invention introduces an auxiliary combustion device as an intermediary to assist in the combustion of alternative fuels. This device provides additional heat input and helps maintain the minimum burning temperatures required for alternative fuels, making their use feasible in the calciner while still achieving climate neutrality benefits.
Solution Approach 2:
The system adjusts combustion parameters including temperature, residence time, and oxygen supply to optimize the combustion of alternative fuels. By controlling these parameters, the system overcomes the ignition difficulties of alternative fuels while meeting the minimum burning requirements.
3Loss of energy
If the combustion chamber is positioned within or directly adjacent to the calcinator, then heat loss is reduced and investment costs are saved, but exhaust gas treatment at optimal temperatures becomes difficult
Solution Approach 1:
The invention segments the gas flow path by creating a separate routing for exhaust gases through the combustion chamber, distinct from the solids stream. This segmentation allows the exhaust gases to be heated to optimal treatment temperatures in the combustion chamber while the calcinator operates independently at its required temperature, resolving the conflict between heat loss reduction and temperature control.
4Temperature
If the combustion chamber is positioned outside the solids stream with a residence time device, then exhaust gas treatment at ideal temperatures is achieved, but device complexity increases
Solution Approach 1:
The combustion chamber serves multiple functions: it provides heat for the calcination process, acts as a residence time device for exhaust gas treatment, and functions as the primary combustion zone for alternative fuels. This multi-functionality reduces the need for separate dedicated treatment devices, thereby limiting the increase in device complexity despite the modified configuration.
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
Reduces energy consumption by eliminating the need for reheating and subsequent treatment, achieving effective pollutant conversion at lower calcinator temperatures, thereby reducing CO₂ emissions and investment costs.
Implementation Method 1
The preheater is designed, for example, as a direct-flow heat exchanger with a cyclone separator or as a cascade of two to six direct-flow heat exchangers with cyclone separators
Implementation Method 2
The preheater is designed, for example, as a direct-flow heat exchanger with a cyclone separator
Implementation Method 3
In the combustion chamber, the thermal energy required for the process is provided by burning natural gas, hydrogen, coal, ammonia, or alternative fuels such as biomass, used tires, or household waste
Implementation Method 4
A temperature range above 800 °C is advantageous for this conversion. Therefore, exhaust gas treatment typically requires reheating the relatively cold exhaust gases
Data Source
Figure 1
AI summary
The present invention relates to a device for thermal treatment, wherein the device has at least one preheater (10), a calciner (20) and a material cooler (30), wherein a solid stream is guided into the preheater (10), from the preheater (10) into the calciner (20), from the calciner (20) into the material cooler (30) and out of the material cooler (30), wherein a gas stream is guided into the material cooler (30), from the material cooler (30) into the calciner (20), from the calciner (20) into the preheater (10) and out of the preheater (10), wherein the device has a combustion chamber (40), wherein the gas stream is guided out of the material cooler (30) at least partially through the combustion chamber (40) into the calciner (20), characterised in that a dwell time device (50) is arranged between the combustion chamber (40) and the calciner (20).