Recirculation Line Economizer Steam Pressure Solar Thermal
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Solution Overview
Problem
The efficiency of solar thermal power plants is limited by the pressure of steam in the Molten Salt Central Receiver (MSCR) system, which is constrained by pinch limitations, leading to suboptimal thermal storage capacity and operational risks such as freezing of molten salt.
Innovation Solution
A solar thermal power system with a recirculation line configured around the economizer section to increase steam pressure by recirculating heated water, maintaining desired temperatures and increasing the heat load on the economizer section, thereby enhancing the efficiency of the Rankine power cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steam pressure is increased to improve power cycle efficiency, then the efficiency of the Rankine power cycle improves, but the risk of molten salt freezing increases due to lower feedwater temperature requirements
Solution Approach 1:
The feedwater is preheated in the economizer section before entering the evaporator, ensuring that the molten salt maintaining temperature remains above the freezing point of the salt mixture throughout the heat exchange process. This preliminary heating action prevents freezing while enabling higher steam pressure operation.
Solution Approach 2:
The system changes the temperature parameters of the feedwater through preheating in the economizer, raising the feedwater temperature to a level that prevents molten salt freezing. This parameter change allows the system to operate at higher steam pressures while maintaining reliable thermal storage conditions.
2Quantity of substance
If molten salt outlet temperature is reduced to increase thermal storage capacity, then the thermal storage capacity increases, but the steam pressure is limited by pinch limitations
Solution Approach 1:
The feedwater receives preliminary heating in the economizer section before entering the evaporator. This preheating action extends the temperature difference available for heat exchange, allowing the molten salt to be cooled to lower temperatures (increasing thermal storage capacity) while still maintaining sufficient temperature gradient to generate high pressure steam.
Solution Approach 2:
The system separates the heating process into distinct stages: preheating in the economizer and evaporation in the evaporator. This dimensional separation of heating functions allows independent optimization of thermal storage capacity (through lower salt outlet temperature) and steam pressure (through extended preheating), resolving the pinch limitation constraint.
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 allows for increased steam pressure in the steam generator arrangement, improving the overall efficiency of the power cycle while preventing freezing of the molten salt, thus enabling more effective thermal energy storage and utilization.
Implementation Method 1
the recirculation line is configured around the economizer section to recirculate the heated water to an inlet of the economizer section
Implementation Method 2
a solar receiver... The heliostats focus direct sunlight on to the solar receiver to produce steam
Implementation Method 3
the molten salt fluid heated at the MSCR is stored in the hot storage tank
Implementation Method 4
a central receiver including a solar energy storage fluid, such as molten salt... the molten salt fluid heated at the MSCR is stored in the hot storage tank, at temperature of about 565°C
Implementation Method 5
An increase of this outlet temperature decreases the thermal storage capacity
Implementation Method 6
The steam generator arrangement utilizes the heat of the hot molten salt and converts feedwater from a feedwater tank in to steam
Implementation Method 7
the water is heated up in the economizer and starts evaporating at a pressure which is determined by the heat balance of the system
Implementation Method 8
The increase of steam pressure increases efficiency of the power cycle, specifically 'Rankine power cycle'
Implementation Method 9
send it to the multi-stage turbine for the conversion of heat to electricity through a generator
Implementation Method 10
a multi-stage turbine... for the conversion of heat to electricity
Data Source
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AI summary
A solar thermal power system 100 includes a solar receiver 110, and a thermal energy storage arrangement 120 having thermal energy storage fluid to be circulated through the solar receiver 110 to store thermal energy. The system 100 includes a multistage steam turbine 130 operable on variable pressure steam generated by a steam generator arrangement 140, by utilizing the thermal energy storage fluid. The arrangement 140 includes an economizer section 142, an evaporator section 144, and a superheater section 148 communicably configured to utilize the heat of the hot thermal energy storage fluid to generate and supply the variable pressure steam to the turbine 130. The system 100 includes a recirculation line 170 configured around the economizer section 142 to recirculate the heated water to an inlet 142a of the economizer section 142, increasing pressure range of the variable pressure steam in the arrangement 140.