ANALYSIS OF ENERGY CONSUMPTION ECONOMY IN CRYOGENIC SYSTEMS BY THE USE OF HEAT EXCHANGERS

Abstract

Evaluation of energy consumption economy due to implementation of the principle of cold regeneration is a formidable problem of exergy analysis of cryogenic systems. A method or evaluation of power consumption economy due to the presence of heat exchangers in the scheme of cryogenic plant is suggested in the present article. The calculations of the economy for the refrigeration and liquefaction regimes of cryogenic nitrogen plant operating in accordance with a simple throttle cycle have been carried out. The approximate method for evaluation of power consumption economy demonstrated that for a simple throttle cycle the use of the heat exchanger enables to reduce power costs by about 30 % regardless of the mode of operation. The use of a heat exchanger makes it possible to avoid the problems associated with the use of work produced in the expander. The analysis of the results of the performed calculations demonstrated that the economy is practically independent on the operating regime. For the analyzed systems the minimal pressures of the working fluid after compressor that are needed to obtain a specified quantity of a product of required quality have been determined. The calculations made for Linde cycle demonstrated that this value depends on the mode of operation, but it is significantly less than the pressure in the cycle. The presented approach to determining the economy of energy consumption in low-temperature systems is applicable to power plants due to the presence of heat exchangers in its design. For such an application one need to override the purpose of these devices and to alter the equations exergy balances in accordance with it.

Keywords

• exergetic method
• thermodynamic analysis
• cold regeneration
• heat exchanger
• power consumption
• pressure of cycle