Once-Through Steam Generator Tube Temperature Imbalance Control
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Solution Overview
Problem
Once-through steam generators with vertically arranged evaporator tubes experience significant temperature imbalances due to uneven heating, which are exacerbated by increasing system efficiency requirements and varying load ranges, making it difficult to manage heating inconsistencies across different tube groups.
Innovation Solution
The solution involves segmenting the combustion chamber into representative wall areas with controlled mass flow distribution using inlet and outlet collectors, temperature measuring means, and control valves to regulate feed water supply, ensuring that more heated tube groups receive higher flow rates and less heated groups receive lower flow rates, thereby minimizing temperature imbalances across the entire load range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If vertically arranged evaporator tubes are used in combustion chamber walls, then construction simplicity and manufacturing costs are improved, but temperature imbalances between tubes are significantly worsened
Solution Approach 1:
The combustion chamber walls are divided into multiple heating zones based on thermal load characteristics. Tubes experiencing similar heating conditions are grouped together, allowing for zone-specific mass flow control that compensates for the inherent temperature imbalances in vertical tube configurations while maintaining construction simplicity
Solution Approach 2:
The invention dynamically adjusts mass flow parameters through control valves in feed water supply lines to different heating zones. By changing flow rates according to local heating intensity, the system compensates for temperature imbalances without altering the simple vertical tube arrangement, thus maintaining manufacturing ease while improving thermal uniformity
2Temperature
If low-mass flux design is applied to vertical tubing, then temperature imbalances are reduced, but system efficiency and adaptability to varying load ranges are worsened
Solution Approach 1:
The invention introduces dynamic control elements (control valves) in the feed water supply lines to different heating zones. These valves enable real-time adjustment of mass flow rates according to actual thermal loads and temperature measurements, allowing the system to adapt to varying load ranges while maintaining temperature balance through active feedback control
Solution Approach 2:
Temperature measuring means are installed to monitor outlet temperatures from evaporator tube groups. These measurements feed back to control systems that adjust mass flow rates through control valves, creating a closed-loop control system that maintains temperature balance across different load conditions rather than relying on fixed low-mass flux design
3Quantity of substance
If geometrically coordinated supply lines with throttling orifices are used, then mass flow distribution is improved for specific load ranges, but system flexibility and adaptability to heat distribution variations are worsened
Solution Approach 1:
The invention replaces fixed geometric coordination and static throttling orifices with dynamic control valves that can adjust opening positions based on real-time temperature measurements and load conditions. This allows the system to optimize mass flow distribution adaptively rather than being constrained to a single design-point optimization
Solution Approach 2:
Temperature measuring means provide continuous feedback on actual thermal conditions in different heating zones. This feedback enables the control system to adjust mass flow rates through control valves to compensate for deviations from design conditions, making the system resilient to heat distribution variations without requiring precise a priori knowledge
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 effectively minimizes temperature imbalances in the steam generator with minimal additional effort, potentially eliminating the need for reversing collectors and reducing costs, while ensuring dynamic stability and flexibility to handle varying heat distributions and load conditions.
Implementation Method 1
temperature measuring means for measuring the outlet temperatures of the flow medium from the evaporator tubes are provided for determining a control variable for the at least one control valve
Implementation Method 2
at least one control valve for regulated throttling of the mass flow of the feed water and thus the flow medium flowing through the evaporator tubes is provided
Implementation Method 3
The heating of these evaporator tubes, which form the combustion chamber walls, leads here to complete evaporation of the flow medium in one pass
Implementation Method 4
The heating of these evaporator tubes, which form the combustion chamber walls, leads here to complete evaporation of the flow medium in one pass
Data Source
Figure 1~2
AI summary
The invention relates to a once-through steam generator, in particular forced-flow once-through steam generator, having a combustion chamber (1) of substantially rectangular cross section, the combustion chamber walls of which comprise substantially vertically arranged evaporator pipes, connected to one another in gas-tight fashion by means of pipe webs, of the once-through steam generator, through which evaporator pipes a flow medium can flow from bottom to top, wherein the evaporator pipes of the combustion chamber walls are, in accordance with their degree of heating, combined by way of upstream inlet collectors in each case to form more intensely heated pipe groups (10) and less intensely heated pipe groups (11), and wherein a feed water supply (20, S1, S2, S3, S4) is assigned to the respective inlet collectors. Here, at least one regulating valve (R, R1, R2, R3, R4) for the regulated throttling of the mass flow of the flow medium into the evaporator pipes is provided in the region of the feed water supply (20, S1, S2, S3, S4), and to determine a control variable for the at least one regulating valve (R, R1, R2, R3, R4), temperature measurement means for measuring outlet temperatures of the flow medium exiting the evaporator pipes are provided in the region of downstream outlet collectors, and wherein each of the more intensely heated pipe groups (10) and less intensely heated pipe groups (11) is assigned to in each case one of the inlet collectors and to an outlet collector, and each of the outlet collectors has one of the temperature measurement means.