A low-grade thermal energy power generation method and device

Abstract

The invention relates to a novel low-grade heat energy power generation method, which comprises two processes as follows: low-grade heat energy is converted into chemical potential energy of a solution through a generator; the chemical potential energy of the solution is converted into electric energy for outputting through a reverse electrodialysis (RED) cell stack; after the chemical potential energy of the solution is converted into the electric energy, the concentration of a concentrated solution is lowered and the concentration of a dilute solution is increased; the concentrated solution and the dilute solution flow out of the RED cell stack to be mixed into a median-concentration solution; and the median-concentration solution is heated by a solution heat exchanger, and then enters a generator to be heated and separated again by the low-grade heat energy, thereby finishing a power generation cycle. The novel low-grade heat energy power generation method has the advantages that (1) the low-grade heat energy can be fully, continuously and gradiently utilized; (2) a power generation system is simple, reliable and flexible in capacity configuration, and has a storage function; and (3) the working cycle is a negative-pressure closed working cycle, and is safe, reliable, environment-friendly and free of noise.

Description

technical field [0001] The invention belongs to the technical field of low-grade thermal power generation, and relates to a low-grade thermal power generation method and device. Background technique [0002] The existing low-grade thermal power generation technology mainly adopts the heat-work conversion Rankine cycle power generation technology, that is, the use of thermal energy to vaporize the liquid working medium under relatively high pressure, and the relatively high temperature and high pressure steam drives the centrifugal turbine or screw expander Output shaft work and drive the generator to generate electricity; the temperature and pressure of the steam expanded in the centrifugal turbine or screw expander decrease, and then condense into liquid in the condenser, and finally use the pump to pressurize the liquid working medium to pump again To the boiler or evaporator for re-gasification. For low-grade thermal power generation with relatively high temperature, the...

AI Technical Summary

Problems solved by technology

[0003] For the traditional Rankine cycle using water as the working medium, due to the high critical point of water vapor, the efficiency of converting low-grade heat energy into electrical energy is reduced, and the size and weight of the turbine or screw expander increase

For the Organic Working Fluid Rankine Cycle (ORC) formed by replacing water with organic working fluid, its inherent defects include: 1) the organic working fluid used is hydrofluorocarbons (HFCs) with a higher GWP (Global Warming Potential) value ) substances, or flammable and explosive hydrogen hydrocarbons (HCs) substances; 2) For low-grade thermal power generation with different temperature levels, different types of organic working fluids need to be selected, and the working fluids have poor versatility; 3) For temperature and heat changes For large-scale low-grade thermal power generation, organic working fluid turbines are not only difficult to develop but also have poor versatility, making it difficult to form series; 4) Due to the small latent heat of gasification of organic working fluids, the pump power consumption is large When the grade heat energy temperature is lower than 70°C, the output net work of ORC decreases sharply with the decrease of low-grade heat energy temperature; 5) The heat-work conversion cycle including ORC itself has no energy storage function, and it is difficult to adapt to unstable low-grade heat source power generation need

The disadvantages of this cycle are: 1) The ammonium bicarbonate solution requires a certain decomposition temperature (>60°C), and the low-grade heat energy with a temperature lower than this value cannot be used; 2) When the temperature of the low-grade heat energy is high, the multi-effect way to reuse the heat energy generated by the separation process, resulting in low energy conversion efficiency; 3) the cycle itself is difficult to store energy

This cycle also has the above-mentioned defects, and the manufacturing cost of the hydraulic turbine is relatively high. It is difficult to form a series of low-grade heat energy with large temperature and heat changes.

lead to a reduced likelihood of practical application

Images