ORC Expansion Machine Model-Based Coupling Control
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Solution Overview
Problem
Thermodynamic cycle process apparatuses, such as Organic Rankine Cycle (ORC) systems, face damage risks due to unsynchronized power supply to expansion machines when coupled with external devices like generators or combustion engines, particularly in screw expansion machines, as existing speed measurement methods are costly or impractical.
Innovation Solution
Implementing model-based control and monitoring to adjust the feed pump's volume flow based on measured exhaust steam pressure and target rotational speed, allowing for power-neutral coupling and operation of the expansion machine, thereby avoiding damage by eliminating the need for expensive speed measurement systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If speed measurement is implemented to ensure power-neutral coupling, then coupling safety is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent uses exhaust steam pressure as an intermediary parameter to indirectly determine expansion machine speed and coupling state, avoiding direct speed measurement. The control device calculates speed based on the relationship between exhaust steam pressure and machine operation, providing a cost-effective mediator that resolves the contradiction between reliable coupling detection and system complexity
Solution Approach 2:
The patent replaces mechanical/electrical speed measurement systems with a pressure-based control system. By substituting direct speed sensing with exhaust steam pressure measurement and computational modeling, the system achieves coupling safety without complex mechanical tachometers or electrical sensors on the expansion machine shaft
2Measurement precision
If direct shaft access is provided for speed measurement, then measurement accuracy is improved, but machine design complexity and cost increase
Solution Approach 1:
The patent employs exhaust steam pressure as a remote intermediary that correlates with expansion machine speed without requiring physical access to the shaft. This mediator enables speed determination through pressure measurements taken at accessible locations in the steam pathway, eliminating the need for shaft penetration or direct contact measurements
Solution Approach 2:
The patent creates a virtual model of expansion machine speed based on exhaust steam pressure characteristics. Instead of directly measuring the physical shaft rotation, the system computes a representative speed value from pressure data, effectively copying the speed information through thermodynamic parameter correlation
3Reliability
If model-based control is implemented to adjust feed pump volume flow, then operational safety is improved, but control system complexity increases
Solution Approach 1:
The patent implements a feedback control loop where exhaust steam pressure is continuously measured, compared against model predictions, and used to adjust feed pump volume flow. This closed-loop feedback mechanism ensures operational safety by automatically correcting deviations from the power-neutral operating point based on real-time pressure measurements
Solution Approach 2:
The patent controls operational safety by dynamically adjusting the feed pump volume flow parameter based on exhaust steam pressure measurements. By changing this key operating parameter in response to pressure variations, the system maintains safe operating conditions without requiring complex multi-parameter control
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 ensures safe operation by maintaining the expansion machine at a power-neutral state during coupling and operation, reducing the risk of damage and operational costs associated with speed measurement, while also enabling controlled shutdowns and efficient energy management.
Implementation Method 1
adjusting a volume flow of the feed pump in accordance with a computer-implemented control model of the thermodynamic cycle process apparatus as a function of the measured exhaust steam pressure and a target rotational speed of the expansion machine
Implementation Method 2
an expansion machine (20) for power-generating expansion of a working medium
Implementation Method 3
Organic Rankine Cycle (ORC) apparatus
Implementation Method 4
a condenser (30) for heating, condensing and sub-cooling the working medium
Implementation Method 5
an evaporator (10) for preheating, evaporating and overheating a working medium
Data Source
AI summary
The invention refers to a method for controlling a thermodynamic cycle process apparatus, in particular an ORC apparatus, wherein the thermodynamic cycle process apparatus comprises an evaporator, an expansion machine, a condenser and a feed pump, and the expansion machine is coupled to an external apparatus in normal operation, and wherein the method comprises the following steps: measuring an exhaust steam pressure downstream of the expansion machine; and setting a volume flow of the feed pump in accordance with a computer-implemented control model of the thermodynamic cycle process apparatus according to the measured exhaust steam pressure and a target rotational speed of the expansion machine as input variables of the control model and with the volume flow of the feed pump as an output variable of the control model. The invention further refers to a corresponding thermodynamic cycle process apparatus.