Method for operating a heat exchanger, arrangement with a heat exchanger, and system with a corresponding arrangement
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Solution Overview
Problem
Heat exchangers in cryogenic systems face thermal stresses and damage when shut down and restarted due to temperature equalization and differential thermal expansion, leading to material issues and increased maintenance costs.
Innovation Solution
A method for operating heat exchangers that involves maintaining temperature profiles during standstill phases by using a gas chamber for heat transfer without solid contact, allowing for controlled heating and cooling of the warm end while keeping the cold end uncooled, and utilizing boil-off gas for temperature control, reducing thermal stresses and energy wastage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the heat exchanger is shut down and allowed to heat up, then the system can be taken out of operation, but thermal stresses occur due to temperature equalization and differential thermal expansion
Solution Approach 1:
The patent applies preliminary action by actively cooling the cold end of the heat exchanger during standstill phases before restart. This pre-cooling prevents temperature equalization and maintains the temperature profile, avoiding thermal stresses when the system restarts. The cooling is performed in advance to prepare the heat exchanger for operation without causing damage.
Solution Approach 2:
The patent applies preliminary anti-action by counteracting the natural heating tendency of the heat exchanger during standstill. Instead of allowing the heat exchanger to heat up passively, an active cooling system is engaged to oppose the temperature rise, maintaining the cold end at its operational temperature and preventing thermal expansion damage.
2Strength
If the heat exchanger is actively cooled during standstill to maintain temperature profile, then thermal stresses are reduced, but energy consumption increases
Solution Approach 1:
The patent applies self-service by using the boil-off gas from the cryogenic storage as the cooling medium during standstill phases. Instead of requiring external energy input for active cooling, the system utilizes its own waste cryogenic gas to cool the heat exchanger, converting a waste product into a useful resource and eliminating additional energy consumption.
Solution Approach 2:
The patent applies discarding and recovering by capturing the boil-off gas that would normally be vented and discarding it to waste, and instead recovering it for use as the cooling medium in the heat exchanger during standstill phases. This transforms a discarded waste stream into a valuable resource for maintaining system integrity.
3Temperature
If the heat exchanger is actively cooled during standstill, then temperature profiles are maintained, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the cooling system to serve multiple functions: it cools the heat exchanger during standstill phases, utilizes the boil-off gas that would otherwise be wasted, and can be integrated with the existing cryogenic storage infrastructure. This multi-functionality reduces the need for separate dedicated cooling equipment, thereby limiting the increase in device complexity.
4Use of energy by moving object
If the heat exchanger is allowed to heat up during standstill, then energy consumption is reduced, but thermal loading and damage occur upon restart
Solution Approach 1:
The patent applies blessing in disguise by converting the harmful effect of boil-off gas (which would normally be vented to waste and represents energy loss) into a beneficial cooling resource. The boil-off gas, instead of being a waste product contributing to energy consumption, is utilized as the cooling medium to maintain the heat exchanger temperature profile, thereby converting harm into benefit.
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 minimizes thermal loading and damage to the heat exchanger, reduces energy consumption, and effectively maintains temperature profiles during startup and shutdown, enhancing operational efficiency and extending equipment lifespan.
Implementation Method 1
heat provided by means of a heating device is supplied to the first region via a gas chamber which is located outside the heat exchanger and within which the first region is arranged or which surrounds the first region
Implementation Method 2
heat provided by means of a heating device is supplied to the first region
Implementation Method 3
heat exchangers (more technically correct: heat transfer devices) are operated with cryogenic fluids
Implementation Method 4
the temperatures at the previously warm end and at the previously cold end equalize due to the good thermal conduction (thermal longitudinal conduction) in its metallic material
Data Source
AI summary
A method for operating a heat exchanger, in which a first operating mode is carried out in first time periods, and a second operating mode is carried out in second time periods that alternate with the first time periods; in the first operating mode a first fluid flow is formed at a first temperature, is fed into the heat exchanger in a first region at the first temperature, and is partially or completely cooled in the heat exchanger; in the first operating mode a second fluid flow is formed at a second temperature, is fed into the heat exchanger in a second region at the second temperature, and is partially or completely heated in the heat exchanger; and in the second operating mode the feeding of the first fluid flow and of the second fluid flow into the heat exchanger is partially or completely halted.