District Heating Return-Line Utilization to Reduce Fuel Consumption

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Solution Overview

Problem

The high temperature of the return side in district heating systems reduces efficiency and increases fuel costs in bio-power plants, as it leads to poor heat utilization and inefficient operation of flue gas scrubbers.

Innovation Solution

Introducing a system with two return lines and one inlet line from the district heating network, where the heat energy from both lines is utilized for property heating, allowing for the efficient use of excess heat and reducing the temperature of the return water, thereby improving fuel efficiency without requiring technical changes to the power plants.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the return side temperature is high, then the heating capacity is sufficient, but the fuel efficiency decreases and flue gas scrubber efficiency decreases

Engineering Contradiction:
Improvereturn side temperatureVSAvoidfuel efficiency
Core Design Contradiction:
TemperatureVSUse of energy by moving object

Solution Approach 1:

The patent divides the heating system into two separate circuits: a primary circuit using the inlet line for high-temperature heating, and a secondary circuit using the return side for low-temperature heating. This segmentation allows each circuit to operate at optimal temperatures, with the return side specifically utilized for preheating or supplementary heating, thereby reducing the temperature burden on the power plant while maintaining sufficient heating capacity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the temperature parameter utilization by introducing a two-circuit system where the return side temperature is deliberately maintained at a lower level suitable for preheating or low-temperature heating applications. This parameter change enables the power plant to operate more efficiently while still meeting heating demands through the combined effect of both circuits.

Inventive Principle:
Principle #35Parameter changes

2Temperature

If the return side temperature is high, then heating demand is met, but flue gas scrubber efficiency decreases

Engineering Contradiction:
Improvereturn side temperatureVSAvoidflue gas scrubber efficiency
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent segments the heating load into two parts: high-temperature heating from the inlet line and low-temperature heating from the return side. This segmentation ensures that the return side temperature remains lower, creating more favorable conditions for flue gas scrubber operation and improving reliability of emissions control.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies parameter changes by utilizing the return side at a lower temperature range that is compatible with flue gas scrubber efficiency requirements. This temperature parameter adjustment allows the scrubber to operate more effectively while the inlet line compensates for any reduced heating capacity.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If only inlet line heat is used, then the system is simple, but the usable heating range is limited

Engineering Contradiction:
Improvesystem complexityVSAvoidusable heating range
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent makes the heating system multi-functional by enabling it to operate in different modes: using only the inlet line for high-temperature heating, using only the return side for low-temperature heating, or combining both circuits. This universality allows the system to adapt to various heating demands and building requirements, significantly expanding the usable heating range while maintaining operational simplicity through standardized components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 extends the usable heating range of the district heating network, reduces fuel consumption, and increases the efficiency of flue gas scrubbers, allowing for cost-effective heating solutions with minimal user-end changes, while enabling the sale of excess heat and reducing emissions.

Implementation Method 1

the heat from the water of the district heating network's outlet is transferred through heat exchangers to the property's heat distribution units

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

the heat energy of both inlet line and the return side can be used for heating

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentEP3502575B1Building heating system and connection method
Publication Date: 2020.09.09 IOTOI OY
  • EP3502575B1 patent drawingFigure 1
  • EP3502575B1 patent drawingFigure 2
  • EP3502575B1 patent drawingFigure 3

AI summary

There is a property heating system and a method where the heat energy of the district heating line and the return line can be used for heating. In addition, it is possible to sell the heat/waste heat of the property for use in the return line. The system comprises a high temperature section (102) for heating hot water (112) and a low temperature section (104) for heating the property. The high temperature section of the property's heating system is connected to the district heating outlet line (106). The outlet (132) of the low temperature section (104) is connected via a circulation pump (114) to the district heat return line (108). The return (134) of the low temperature section (104) is connected to the return line (108) of the district heat at a distance (116) from the outlet (132) of the low temperature section (104).