Supercritical CO2 Cycle Split Flow Pipe Reduces Boiler Pressure Drop
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Solution Overview
Problem
The supercritical CO2 cycle in coal-fired power generation systems experiences a large pressure drop and reduced boiler efficiency due to increased mass flow and residual heat absorption issues, which are not effectively addressed by existing technologies.
Innovation Solution
A supercritical CO2 cycle system with a compressor unit and turbine unit, featuring a split flow pipe connecting the compressor exhaust to the turbine, an auxiliary regenerator, and an auxiliary heater, which reduces the mass flow into the preceding stage heater, thereby decreasing boiler resistance and pressure drop, and optimizing the cycle process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the supercritical CO2 cycle employs the same pulverized coal-fired boiler structure as the steam Rankine cycle, then the boiler structure can be maintained unchanged, but the pressure drop of the boiler increases significantly due to increased mass flow
Solution Approach 1:
The patent divides the CO2 flow path into multiple segments: a first path through the preceding stage heater and a second path through the last stage heater. This segmentation allows the high mass flow CO2 to be distributed across multiple heating sections, reducing the flow concentration in any single section and thereby lowering the overall pressure drop while maintaining the existing boiler structure.
Solution Approach 2:
The patent introduces a spatial dimension by routing CO2 through different stages (preceding stage and last stage) of the boiler heating system. This multi-stage arrangement transforms a single-point flow problem into a distributed spatial flow pattern, reducing pressure drop without changing the boiler's physical structure.
2Temperature
If the minimum temperature of CO2 entering the boiler is high (about 510°C for double reheat), then the cycle can proceed, but residual heat in the tail flue cannot be effectively absorbed, reducing boiler efficiency
Solution Approach 1:
The patent introduces an intercooler between the compressor and the boiler that performs preliminary cooling of the CO2 before it enters the boiler. This preliminary action reduces the CO2 temperature to a level that allows effective heat absorption from the tail flue, thereby capturing residual heat that would otherwise be lost, while still maintaining the necessary temperature for the cycle to proceed.
Solution Approach 2:
The intercooler acts as an intermediary device between the compressor and the boiler. It mediates the temperature of the CO2 flow, providing an optimal temperature entry point that enables both cycle operation and effective residual heat absorption from the exhaust gases.
3Productivity
If the mass flow of CO2 is increased 6 to 8 times compared to steam Rankine cycle, then the supercritical CO2 cycle can operate, but the resistance of the boiler increases due to increased mass flow
Solution Approach 1:
The patent segments the high mass flow CO2 stream into multiple paths through the preceding stage heater and last stage heater. This segmentation distributes the high flow rate across multiple heating sections, reducing the flow concentration and friction resistance in any single section while maintaining the total mass flow required for the supercritical CO2 cycle.
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 reduces boiler resistance and pressure drop, improves boiler efficiency, and enhances the overall thermal system efficiency by optimizing the cycle process and residual heat absorption.
Implementation Method 1
the auxiliary regenerator and an auxiliary heater are provided on the split flow pipe, and the auxiliary regenerator is located upstream of the auxiliary heater
Implementation Method 2
a compressor unit and a turbine unit, wherein the turbine unit includes a preceding stage heater, a preceding stage turbine, a last stage heater and a last stage turbine successively connected in series
Implementation Method 3
a preceding stage heater, a preceding stage turbine, a last stage heater and a last stage turbine successively connected in series
Implementation Method 4
an auxiliary regenerator and an auxiliary heater are provided on the split flow pipe, and the auxiliary regenerator is located upstream of the auxiliary heater
Data Source
AI summary
A coal-fired power generation system and a supercritical CO2 cycle system thereof are provided. The supercritical CO2 cycle system includes a compressor unit and a turbine unit. The turbine unit includes a preceding stage heater, a preceding stage turbine, a last stage heater and a last stage turbine successively connected in series. An exhaust port of at least one of compressors in the compressor unit is in communication with the turbine unit through a split flow pipe, and a communication position between the split flow pipe and the turbine unit is located downstream of a suction port of the preceding stage turbine. An auxiliary regenerator and an auxiliary heater are provided at the split flow pipe, and the auxiliary regenerator is located upstream of the auxiliary heater.