Solar Boiler Secondary Air Superheating With Heat-Medium Mediation
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Solution Overview
Problem
Conventional solar thermal energy systems for gas turbines require a large number of mirrors to achieve high air temperatures, leading to increased installation costs and unstable operation due to the need for tall structures, while they do not effectively apply solar thermal energy to boiler systems.
Innovation Solution
A solar boiler system that uses a solar heat recovery apparatus to input solar thermal energy into a coal-fired thermal power boiler via a secondary air superheater, reducing the number of mirrors needed and stabilizing the operation by using a trough or tower type solar heat recovery system with oil or molten salt as a heat medium, allowing for efficient thermal energy storage and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If solar light is concentrated to superheat air to 1000°C or higher in a gas turbine system, then thermal efficiency is improved, but the installation cost of the solar collector is significantly increased
Solution Approach 1:
The patent introduces a heat transfer medium (oil or molten salt) as an intermediary between the solar collector and the boiler. The solar collector heats the medium to a moderate temperature (200-500°C), and the heated medium then transfers thermal energy to the boiler water/steam. This intermediary approach allows solar energy to be captured efficiently without requiring the solar collector to achieve the extremely high temperatures (1000°C+) needed in direct gas turbine applications, thereby reducing collector complexity and cost while maintaining good thermal efficiency.
Solution Approach 2:
The patent changes the temperature parameter at which solar energy is captured. Instead of concentrating solar light to achieve 1000°C or higher directly in the working fluid (as in gas turbines), the system captures solar thermal energy at moderate temperatures (200-500°C) using a heat transfer medium. This parameter change enables the use of simpler, less expensive solar collectors while still achieving significant thermal efficiency improvements in the boiler system.
2Temperature
If a large number of flat mirrors are installed to achieve high air temperature, then solar heat concentration is improved, but the area required for mirror installation is enormously increased
Solution Approach 1:
By using a heat transfer medium as an intermediary, the system achieves effective thermal energy transfer without requiring extreme temperature concentration. The moderate temperature range (200-500°C) required for heating the heat transfer medium can be achieved with a more compact solar collector arrangement, significantly reducing the land area needed for mirror installation compared to systems requiring 1000°C or higher temperatures.
Solution Approach 2:
The patent changes the target temperature parameter from extreme temperatures (1000°C+) to moderate temperatures (200-500°C). This parameter change allows the solar collector to be much more compact, reducing the area required for mirror installation while still achieving significant thermal efficiency improvements in the boiler system.
3Loss of energy
If high temperature and high pressure air expansion turbine and generator are installed on a tall tower, then solar heat recovery is achieved, but stable operation becomes difficult
Solution Approach 1:
The patent uses a heat transfer medium (oil or molten salt) as an intermediary to decouple the solar collector from the boiler system. This allows the solar collector to be positioned optimally for heat collection while the boiler and turbine-generator can be located on stable, accessible ground-level platforms. The heated medium is pumped to the boiler where thermal energy is transferred to water/steam, which then drives the turbine-generator without requiring installation on tall towers.
4Loss of energy
If solar thermal energy is applied to superheat air in a gas turbine system, then energy efficiency is improved, but the device complexity is significantly increased
Solution Approach 1:
The patent introduces a heat transfer medium as an intermediary that simplifies the overall system architecture. The solar collector heats the medium, which is then pumped to the boiler for thermal energy transfer. This intermediary approach avoids the complexity of direct air heating systems while achieving comparable or better energy efficiency. The system integrates smoothly with conventional boiler and turbine-generator equipment, minimizing additional complexity.
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 system significantly reduces installation costs and improves gross thermal efficiency by minimizing air temperature rise, allowing for stable operation and consistent energy output, as it superheats secondary air to 400-500°C, reducing coal consumption and maintaining turbine generator output throughout the day.
Implementation Method 1
solar light is concentrated in the solar heat receiving unit by means of a large number of flat mirrors installed on the ground
Implementation Method 2
a solar heat receiving unit is installed on the leading end of a tower having a height of approximately 100 m from the ground. Solar light reflected from a large number of reflecting mirrors installed on the ground is collected in the solar-heat receiving unit
Implementation Method 3
A solar boiler system that uses a solar heat recovery apparatus to input solar thermal energy into a coal-fired thermal power boiler via a secondary air superheater
Implementation Method 4
The high-pressure air thus superheated is supplied to the high temperature and high pressure air expansion turbine
Implementation Method 5
This high pressure and high temperature air is made to flow in a high temperature and high pressure expansion turbine installed on the leading end of the above-mentioned tower so that a generator is driven to generate electricity
Data Source
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AI summary
It is an object of the present invention to provide a solar boiler system that can suppress the installation cost for a solar heat collector and significantly improve gross thermal efficiency while minimizing a rise in air temperature resulting from the collected solar heat. The solar boiler system of the present invention includes a boiler 10 for burning fossil fuel; a primary air system for pneumatically transporting pulverized fossil fuel to a burner attached to the boiler 10; a secondary air system for supplying preheated air for combustion to the boiler 10; and a secondary air superheater 7 provided at the secondary air system, the secondary air superheater 7 further superheating the preheated air for combustion with solar thermal energy.