Deduster Inlet Temperature Control via Combustion Gas Bypass
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Solution Overview
Problem
In oxyfuel combustion boilers, the inlet temperature of the deduster is not maintained above the acid dew-point, leading to potential sulfuric acid corrosion, as existing technologies lack effective temperature control measures.
Innovation Solution
A method and apparatus that measure the inlet temperature of the deduster and adjust the combustion support gas bypass through the preheater and flue gas cooler to maintain the temperature above the acid dew-point, using bypass lines and flow control dampers to regulate the gas flow and prevent corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the flue gas is cooled by the flue gas cooler to reduce temperature, then the flue gas outlet temperature decreases, but the temperature drops below the acid dew-point causing sulfuric acid corrosion
Solution Approach 1:
The patent introduces a bypass line as an intermediary pathway that allows flue gas to circumvent the flue gas cooler when temperature approaches the acid dew-point. This mediator enables temperature control without modifying the main cooling process, preventing sulfuric acid corrosion by maintaining temperature above the dew-point while still allowing efficient cooling operation under normal conditions
Solution Approach 2:
The system dynamically changes the temperature parameter of flue gas by controlling the bypass damper opening degree. When the outlet temperature approaches the acid dew-point, the bypass damper opens to mix hotter bypassed flue gas with cooled flue gas, raising the temperature above the corrosion threshold. This parameter adjustment resolves the contradiction between cooling efficiency and corrosion prevention
2Temperature
If the combustion support gas bypasses the preheater to increase inlet temperature of deduster, then the inlet temperature increases above acid dew-point, but the preheater efficiency decreases
Solution Approach 1:
The patent applies partial bypassing of combustion support gas through the bypass line rather than complete bypass. The bypass damper is controlled to open only partially when needed, allowing most of the combustion support gas to still pass through the preheater for efficient heat exchange. This partial action maintains inlet temperature above acid dew-point while minimizing energy loss and preserving preheater efficiency under normal operating conditions
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 solution effectively maintains the flue gas outlet temperature above the acid dew-point, preventing sulfuric acid corrosion in the deduster and ensuring operational safety.
Implementation Method 1
a preheater for preheating the combustion support gas by means of flue gas discharged from the boiler
Implementation Method 2
a flue gas cooler for cooling the flue gas having passed through the preheater
Implementation Method 3
adjust the combustion support gas bypass through the preheater and flue gas cooler to maintain the temperature above the acid dew-point, using bypass lines and flow control dampers to regulate the gas flow
Data Source
AI summary
A combustion-support-gas bypass line is provided to cause combustion support gas to bypass a preheater. A combustion-support-gas flow control damper is provided in the combustion-support-gas bypass line. An inlet temperature of a deduster is measured by a temperature sensor and the inlet temperature measured by the temperature sensor is inputted to a controller and is compared with a set temperature more than an acid dew-point preliminarily set in the controller. On the basis of a comparison result, an opening-degree control signal is outputted from the controller to the combustion-support-gas flow control damper so as to make the inlet temperature to a set temperature more than an acid dew-point.