Method and arrangement
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Solution Overview
Problem
District heating power plants in the Nordics face reduced energy efficiency during the summer season due to minimized flue gas heat recovery operations, leading to lower load adjustments and increased energy losses.
Innovation Solution
A method and arrangement that involves passing flue gas through a flue gas cooling unit, where heat is transferred to a cooling liquid, and then to a heat pump connected to both the district heating and cooling systems, allowing for efficient heat energy transfer and temperature regulation throughout the year.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If flue gas heat recovery plants are shut down or minimized during summer season to adjust power plant load, then power plant load is decreased, but overall energy efficiency of the plant is lowered
Solution Approach 1:
The heat pump system is designed to serve multiple functions: heating district heating water during winter, cooling district cooling water during summer, and recovering heat from flue gas year-round. This multi-functionality allows the system to maintain energy efficiency across different seasons by adapting to varying thermal demands in the district heating and cooling networks.
Solution Approach 2:
The system dynamically adjusts its operation based on seasonal conditions and temperature differentials. During summer, when district cooling water is available, the heat pump operates in a mode that recovers heat from flue gas to cool the cooling water, which is then fed back to the flue gas cooling unit. This dynamic adaptation maintains energy efficiency regardless of season.
2Loss of energy
If flue gas cooling temperature is lowered to increase heat recovery, then more heat energy is captured, but condensing temperature is reduced which may affect system performance
Solution Approach 1:
The system changes operational parameters based on seasonal conditions. During summer, district cooling water at lower temperatures is available, allowing the flue gas to be cooled to lower temperatures for maximum heat recovery. During winter, the system operates with higher condensing temperatures appropriate for heating applications. This parameter adaptation optimizes heat recovery while maintaining system performance.
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 approach achieves high energy efficiency year-round by optimizing heat transfer and utilization, reducing energy losses, and allowing for cost-effective and compact system design.
Implementation Method 1
passing the flue gas of the boiler though a flue gas cooling unit, cooling the flue gas in the flue gas cooling unit, said cooling comprising transferring heat from the flue gas into a circulation of a flue gas cooling liquid
Implementation Method 2
transferring in the heat pump heat energy received -- from said cooling liquid and -- from said circulation arrangement of district cooling system -- into said circulation arrangement of district heating system, for -- lowering the temperature of said flue gas cooling liquid and cooling fluid of said district cooling system, and -- raising the temperature of heating fluid of said district heating system
Implementation Method 3
the flue gas is cooled by scrubbing water so that water vapour contained in the flue gas condenses and the released condensing heat may be utilized
Data Source
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AI summary
A method and an arrangement for recovering heat from flue gas of a boiler (10). The method comprises passing the flue gas (G) of the boiler though a flue gas cooling unit (1), cooling the flue gas (G) by transferring heat from the flue gas (G) into a circulation (3) of a flue gas cooling liquid (CL), transferring heat energy of said flue gas cooling liquid (CL) into a heat pump (2), and arranging the heat pump (2) for receiving heat energy also from a circulation arrangement (8) of a district cooling system. The heat pump (2) is coupled to a circulation arrangement (6) of a district heating system, wherein the method further comprises transferring in the heat pump (2) heat energy (H) received from said cooling liquid (CL) and from said circulation arrangement (8) of district cooling system into said circulation arrangement (6) of district heating system, for lowering the temperature of said flue gas cooling liquid (CL) and cooling fluid of said district cooling system, and raising the temperature of heating fluid of said district heating system.