Rankine Cycle Emergency Shutdown via Fluid Drainage
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Solution Overview
Problem
The Rankine cycle's existing emergency shutdown methods are inefficient due to thermal inertia and the persistence of pressurized vapor, preventing quick energy production cessation.
Innovation Solution
A closed circuit with a device that includes a non-return valve and a drain pipe with a valve means to divert the working fluid from the heat exchanger to the reservoir during emergency shutdown, bypassing the expansion machine and reducing the need for high-pressure and temperature-resistant materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple short circuit of the evaporator is used for emergency shutdown, then the structure is simple, but the shutdown speed is slow due to thermal inertia and persistence of pressurized vapor
Solution Approach 1:
The emergency shutdown system is segmented into multiple functional components: a non-return valve positioned near the pump outlet to block vapor flow, a drain pipe with valve means to rapidly evacuate liquid working fluid from the evaporator, and a bypass line for the hot source. This segmentation allows each component to perform its specific function efficiently, achieving rapid shutdown while maintaining reasonable structural complexity.
Solution Approach 2:
The non-return valve is pre-positioned near the pump outlet in a closed position during normal operation. Upon emergency shutdown activation, it immediately opens to prevent vapor from reaching the expansion machine, acting before the vapor can cause further energy production. The drain pipe system is also pre-configured to rapidly evacuate liquid fluid from the evaporator, preventing steam generation before it can occur.
2Loss of time
If a second valve is used to divert vapor upstream of the expansion machine, then energy production stops quickly, but the valve must be made of high-pressure and temperature-resistant materials increasing device complexity and cost
Solution Approach 1:
The invention introduces a drain pipe with valve means as an intermediary element that diverts liquid working fluid from the evaporator to the reservoir, bypassing the expansion machine. This intermediary system handles the fluid in its liquid state, which is already cooled by the pump, thereby reducing the thermal and pressure demands on the valve materials compared to handling hot pressurized vapor directly.
Solution Approach 2:
Instead of diverting hot vapor from the evaporator outlet (as in conventional systems), the invention inverts the approach by diverting liquid working fluid from the evaporator inlet or intermediate point. This inversion allows the use of lower-grade materials since the fluid is in liquid form and has been cooled by the pump, reversing the conventional approach of handling hot vapor.
Data Source
Figure 1~2
AI summary
The present invention concerns a closed circuit (10) functioning according to a Rankine cycle, said circuit comprising at least one pump (12) for circulating and compressing a working fluid in liquid form, a heat exchanger (18) swept by a hot source (23) for evaporating said fluid, means (26) for expanding the fluid in vapour form, a cooling exchanger (34) swept by a cold source for condensing the working fluid, a tank (40) of working fluid, and circulation pipes for the working fluid (44, 46, 48, 50, 52, 54) for circulating said fluid between the pump, the heat exchanger, the expansion means, the condenser and the tank. According to the invention, the circuit comprises a device (56) for draining the fluid contained in the heat exchanger (18).