A Small Pressure Difference Steam Direct Drive High Boost Ratio Working Medium Pump for Organic Rankine Cycle

Abstract

The invention relates to a small-pressure-difference steam direct-driven high-pressurization-ratio working medium pump used in an organic Rankine cycle, which belongs to the field of medium and low-grade energy utilization. In the organic Rankine cycle system, a small part of the pressure difference between the evaporator and the condenser is sacrificed to drive the working medium pump. The piston area of ​​the working medium pump cylinder is larger than that of the liquid cylinder piston, and it is also driven by a small pressure difference. It can achieve a high pressurization ratio for the liquid working medium, so that the working medium pump no longer consumes electric energy, and the remaining pressure difference drives the expander to generate power, and the output work of the expander is all organic Rankine cycle net work. The high-pressure steam that drives the working medium pump is the same working medium as the compressed liquid working medium, so there is no need to consider the problem of working medium leakage. A small part of the pressure difference is utilized in the working fluid pump, the pressure difference before and after the expander is reduced, and the expansion ratio is reduced.

Description

technical field [0001] The invention relates to a low-pressure-difference steam direct-drive high-pressure-ratio working fluid pump used for organic Rankine cycle, and belongs to the field of medium and low-grade energy utilization. Background technique [0002] The organic Rankine cycle system has significant advantages in recycling various medium and low-grade thermal energy such as industrial waste heat and solar energy. The existing research is mainly to use the energy generated by the system for power generation. In the organic Rankine cycle system, the expander is the power output component, and the working fluid pump will consume part of the shaft work of the expander. Since the critical temperature of the organic working fluid is much lower than that of water, compared with the traditional steam power cycle, The theoretical pump work of the organic Rankine cycle is much larger, and in the actual organic Rankine cycle system, the energy consumed by the working fluid p...

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Problems solved by technology

In the organic Rankine cycle system, the expander is the power output part, and the working medium pump will consume part of the shaft work of the expander. Since the critical temperature of the organic working medium is much lower than that of water, compared with the traditional steam power cycle, The theoretical pumping work of the organic Rankine cycle is much larger, but in the actual organic Rankine cycle system, the energy consumed by the working fluid pump is greater than the theoretical pumping work, so the pumping work of the organic Rankine cycle cannot be ignored, in some may also have an important impact on the organic Rankine cycle

The disadvantage of the electric working fluid pump is that the efficiency of the working fluid pump is too low, especially in the small-scale organic Rankine cycle, there is a large irreversible loss in the working fluid pump. Someone has studied a pumpless organic Rankine cycle, which does not need The pressurization of the working medium pump, but the output power of the system is small and unstable

The traditional working medium pump and the motor are connected by a coupling, and most of them use mechanical seals for shaft sealing, but the shaft seal is a vulnerable part, and the organic working medium is easy to leak at the shaft seal

In addition, under the condition of high temperature difference, the expansion ratio is large, and the performance of the expander is seriously attenuated under the condition of large expansion ratio, resulting in a decrease in the efficiency of the organic Rankine cycle

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