Waste Heat Discharge Flow Stabilization

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Solution Overview

Problem

In nuclear power plants, the waste heat discharge system faces challenges during reactor shutdown, where decay heat generates significant thermal loads. This can lead to fluctuations in condensate water flow rates, causing pipe rupture risks due to load forces and thermal fatigue.

Innovation Solution

A waste heat discharge system incorporating a flow control device with pressure sensors, a temperature sensor, a flow control valve, and a controller. This system stabilizes the liquid level in the return line of the condensate liquid, preventing condensate water from impacting a gas-liquid interface and thus eliminating flow rate fluctuations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the heat transfer power is low and the condensate water does not fill the return pipe, then the waste heat discharge system operates with reduced thermal load, but a gas-liquid interface forms in the return pipe causing flow rate fluctuations and pipe rupture risk

Engineering Contradiction:
Improveheat transfer powerVSAvoidpipe rupture risk
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The patent employs a feedback control mechanism where a flow control valve (34) is adjusted based on detected flow conditions to maintain stable condensate water flow. The system continuously monitors the flow state and dynamically adjusts the valve opening to prevent gas-liquid interface formation, thereby eliminating flow rate fluctuations and preventing pipe rupture while maintaining efficient heat transfer.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The waste heat discharge system is designed to automatically stabilize its own flow conditions through the flow control device. The system uses its own operational parameters (flow rate, pressure) to self-regulate the condensate water flow, eliminating the need for external intervention and ensuring continuous reliable operation without manual adjustment.

Inventive Principle:
Principle #25Self-service

2Productivity

If the condensate water flow rate fluctuates due to gas-liquid interface impact, then the system responds to thermal conditions, but large load forces are generated on the pipe causing rupture risk

Engineering Contradiction:
Improveflow rate responseVSAvoidpipe load capacity
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The flow control valve is dynamically adjusted based on real-time flow detection to maintain stable condensate water flow. This feedback mechanism prevents the formation of gas-liquid interface impacts that generate large load forces, thereby protecting the pipe from excessive mechanical stress while maintaining responsive flow rates.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system proactively stabilizes the flow conditions before harmful fluctuations can occur. By continuously monitoring and adjusting the flow control valve, the system prevents the formation of gas-liquid interfaces and the subsequent generation of large load forces, cushioning the pipe against potential mechanical damage before it occurs.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Temperature

If the temperature of the condensate water fluctuates greatly at the condenser outlet, then the heat exchange process varies, but the downstream pipe is subjected to thermal fatigue impact causing rupture risk

Engineering Contradiction:
Improvecondensate water temperatureVSAvoidpipe thermal fatigue resistance
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The flow control device maintains stable condensate water temperature by regulating flow conditions. This feedback control prevents large temperature fluctuations at the condenser outlet, thereby eliminating thermal fatigue impacts on the downstream pipe and ensuring reliable long-term operation.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system stabilizes the temperature parameter of the condensate water by adjusting flow conditions through the flow control valve. By maintaining consistent temperature parameters, the system prevents thermal fatigue in the downstream pipe while allowing the heat exchange process to operate efficiently.

Inventive Principle:
Principle #35Parameter changes

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 system effectively stabilizes the flow rate of condensate water, reducing the risk of pipe rupture due to load forces and thermal fatigue, while maintaining the liquid level near the outlet of the heat exchanger, ensuring safe and efficient waste heat discharge.

Implementation Method 1

a heat exchange device and a temperature buffer tank sequentially connected in series with a steam generator

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

The first pressure sensor, the second pressure sensor, the temperature sensor, and the flow control valve are disposed in a return line of a condensate liquid

Methodology Applied
Scientific EffectPressure detection: Pressure Gradient

Implementation Method 3

the first pressure sensor, the second pressure sensor and the temperature sensor are disposed upstream of the flow control valve

Methodology Applied
Scientific EffectTemperature detection: Temperature Gradient

Data Source

PatentEP4276854B1Waste heat discharge system and flow stabilization method
Publication Date: 2025.04.09 CHINA NUCLEAR POWER TECH RES INST CO LTD
  • EP4276854B1 patent drawingFigure 1
  • EP4276854B1 patent drawingFigure 2

AI summary

The present invention discloses a flow control device, a waste heat discharge system, and a flow stabilization method. The flow control device includes a first pressure sensor, a second pressure sensor, a temperature sensor, a flow control valve, and a controller. The first pressure sensor, the second pressure sensor, the temperature sensor, and the flow control valve are disposed in a return line of a condensate liquid. The first pressure sensor, the second pressure sensor, the temperature sensor and the flow control valve are each communicatively connected to the controller. The present invention is capable of automatically controlling the liquid level in the return line of the condensate liquid by means of a flow control system formed by the first pressure sensor, the second pressure sensor, the temperature sensor, the flow control valve and the processor. In addition, by setting the flow control system in the waste heat discharge system, the liquid level is maintained near the outlet of the heat exchanger, thereby preventing the condensate water from impacting on a gas-liquid interface, achieving the effect of eliminating the fluctuation of the flow rate of the condensate water, and realizing the flow stabilization effect of the waste heat discharge system.