Non-azeotropic working medium dual-stage organic flash evaporation circulation system and heat energy recovery method thereof

Abstract

The invention discloses a non-azeotropic working medium dual-stage organic flash evaporation circulation system and a heat energy recovery method thereof, and belongs to the field of energy recovery.A working medium exchanges heat with a waste heat medium in a heat exchanger after being pressurized by a working medium pump, and enters a high-pressure-stage gas-liquid separator after being throttled by a first throttle valve; a saturated steam after high-pressure-stage flash evaporation enters a high-pressure-stage turbine to do work through expansion, and saturated liquid is throttled again through a second throttle valve to change into a gas-liquid mixture; the gas-liquid mixture and exhaust gas are mixed in a high-pressure-stage mixer, and then enter a low-pressure-stage gas-liquid separator together; saturated steam after the low-pressure-stage flash evaporation enters a low-pressure-stage turbine to do work through expansion, saturated liquid is throttled through a third throttledvalve to change to a gas-liquid mixture, and the gas-liquid mixture and the exhaust gas are mixed in a low-pressure-stage mixer; and the gas-liquid mixture and the exhaust gas are jointly cooled in acondenser. The temperature matching between the circulation and a cold source is improved, the exergy loss caused by single-stage OFC direct throttling is reduced, the system efficiency is improved,and the stepwise efficient use of medium and low temperature thermal energy is realized.

Description

technical field [0001] The invention belongs to the field of energy recovery, and in particular relates to a non-azeotropic working fluid two-stage organic flash cycle system and a heat energy recovery method thereof. Background technique [0002] With the development of society and economy, China's total energy consumption is increasing year by year. According to statistics, China's total energy consumption reached 464 million tons of standard coal in 2018, with an average annual growth rate of 2.2% in the past five years. It can be expected that under the background of China's economy maintaining medium-to-high speed growth, China's demand for energy will further increase. From the perspective of energy consumption structure, China's energy consumption is still dominated by coal, oil, and natural gas. Taking 2016 as an example, the total consumption of coal, oil, and natural gas accounted for about 86.7% of the total energy consumption in that year. On the one hand, the e...

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Problems solved by technology

[0005] The purpose of the present invention is to provide a non-azeotropic working medium two-stage organic flash cycle system and its heat energy recovery method in view of the above shortcomings, and to solve how to improve the temperature matching between the cycle and the cold source, and reduce the direct throttling of single-stage OFC The resulting exergy loss, improving system efficiency, and realizing the cascade efficient utilization of medium and low temperature heat energy, etc.

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