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Solution Overview
Problem
Existing heating boilers with electrostatic precipitators for flue gas filtration face issues such as impaired heat transfer due to deposits on heat exchanger tubes, high-voltage flashover risks, thermal stress on discharge electrodes, and maintenance challenges.
Innovation Solution
The discharge electrode is positioned in an exhaust gas return line, while the collector electrode is located downstream, allowing for ionization of flue gas in a recirculated exhaust gas flow, reducing thermal stress and flashover risks, and facilitating maintenance by keeping the spray electrode outside the boiler. This setup ensures effective particle separation without compromising heat transfer or combustion conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spray electrode is placed inside the hot flue gas flow for electrostatic separation, then particle separation efficiency is improved, but thermal stress on the electrode increases and maintenance becomes difficult
Solution Approach 1:
The spray electrode is extracted from the hot flue gas flow path and relocated to the recirculated exhaust gas flow path. This allows the electrostatic separation function to be maintained while the electrode is no longer exposed to high temperatures, reducing thermal stress and facilitating maintenance access.
2Reliability
If the discharge electrode is positioned in the hot flue gas flow area, then ionization occurs, but the risk of high-voltage flashovers increases and electrode damage during maintenance becomes more likely
Solution Approach 1:
The discharge electrode is extracted from the hazardous hot flue gas flow area and repositioned in the cooler recirculated exhaust gas flow. The electrode maintains its ionization function by being exposed to the ionized recirculated gas, while the risk of flashovers and damage during maintenance is significantly reduced.
Solution Approach 2:
The recirculated exhaust gas flow acts as an intermediary medium, carrying ionized particles from the spray electrode to the collector electrode. This allows the discharge electrode to perform ionization without being directly exposed to the hot flue gas, reducing electrical hazards while maintaining separation efficiency.
3Reliability
If electrostatic separation is implemented in the heat exchanger tubes, then flue gas purification is achieved, but heat transfer efficiency deteriorates due to deposits on tubes
Solution Approach 1:
The electrostatic separation function is segmented from the heat exchanger tube structure. Instead of using the heat exchanger tubes as collector electrodes, a separate collector electrode is installed in the recirculated exhaust gas flow path, allowing the heat exchanger tubes to maintain their original heat transfer function without particle deposits.
Solution Approach 2:
The recirculated exhaust gas flow serves as an intermediary that carries ionized particles away from the heat exchanger tubes to a dedicated collector electrode. This prevents particle deposition on the heat transfer surfaces while maintaining effective flue gas purification through electrostatic separation.
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 configuration minimizes the impact on heat exchanger function, reduces the risk of high-voltage flashovers, and allows for safer and more efficient electrostatic separation, maintaining advantageous heat transfer conditions and reducing pollutant emissions.
Implementation Method 1
the ionized exhaust gas flow is mixed with the flue gas flow from the combustion chamber via the ionization of the recirculated exhaust gas flow caused by the spray electrode
Implementation Method 2
the ionized solid particles of the flue gases from the combustion chamber are deposited on the tube jacket of the heat exchanger tubes
Data Source
Figure 1
Figure 2
AI summary
A heating boiler with a combustion chamber (1), a heat exchanger (6) arranged downstream of the combustion chamber (1), with several exhaust gas flues (9) connected to an induced draft fan (7) and with at least one spray electrode (16) and at least one collector electrode (15 ) Comprehensive electrostatic separator for the flue gas flow from the combustion chamber (1) described. In order to obtain advantageous cleaning conditions, it is proposed that the spray electrode (16) be arranged in an exhaust gas return line (17) leading from the pressure side of the induced draft fan (7) into the smoke gas stream from the combustion chamber (1) for part of the exhaust gas stream and the collector electrode (15 ) the junction of the exhaust gas return line (17) in the flue gas stream from the combustion chamber (1) is downstream in the direction of flow.