Optimization of ethylene refrigeration system using genetic algorithms method

Dissertant

Ramadan, Shuruq Talib

Thesis advisor

Yusuf, Mumtaz Abd al-Ahad
al-Brifkani, Ahmad M.

University

University of Technology

Faculty

-

Department

Department of Chemical Engineering

University Country

Iraq

Degree

Ph.D.

Degree Date

2007

English Abstract

Ethylene refrigeration for gases separation at low temperature and high pressure for olefin production is an important technique in the chemical industry, Since small changes in the operating conditions of such a process can have a significant influence on its economics, optimization is desirable.

The present work was aimed to propose and establish a mathematical model for the ethylene refrigeration system of the ethylene plant in Basrah petrochemical complex NO.1 (PCI) and reformulated as a geometric programming problem using Visual Basic for predicting:- (overall efficiency of the ethylene refrigeration system {% n}and percent of energy saving % E) Through the formulated model shaft work consumption by the centrifugal compressor, refrigeration effect and coefficient of performance of the system were obtained and other parameters concerning the system.

The results of simulation showed a good agreement with the manufacturer manual. In this study the effect of four factors as independent variables on the overall refrigeration system efficiency and percent of energy saving were studied ; evaporaior low pressure (PL) in the range of (1-3)bar compressor discharge high pressure (Ph) in the range of ( 28-32)bar, condcnser degree of sub-cool temperature (Tsub-D) in the range of (6-22)°C and evaporator degree of superheat temperature (Tsup-D) in the range of (l-5)°C.

The main objective of this thesis was to conduct a thermodynamic analysis in terms of mass and.

energy balance for the ethylene vapor compression refrigeration cycle and its components, and followed by optimization technique to find optimum operating conditions for energy conservation , To obtain the optimum conditions ; genetic algorithm method (GAM) technique was applied, thus aimed to minimize the thermodynamic irreversibility i.

e (maximize overall refrigeration system efficiency) and also lower operating cost i.

e (maximize percent of energy saving) ,and the results showed: evaporator low pressure (PL) (2.8 bar), compressor discharge high pressure (Ph) (28,7 bar), condenser degree of sub-cool temperature (Tsub-D) (19°C), and evaporator degree of superheat temperature (Tsup-D) (3.4°C).

At these conditions the overall refrigeration system efficiency is (81.8%) and percent of energy saving is 51.18 % with respect to conditions in the factory. Within the range studied the results showed that, increasing evaporator low pressure caused an increase of overall refrigeration system efficiency and hence, an increase in percent of energy saving, but increasing in compressor discharge high pressure caused a decrease in overall refrigeration system efficiency and percent of energy saving Increasing condenser degree of sub-cool temperature caused an increase in overall refrigeration system efficiency, but has no effect On percent of energy saving , while increasing evaporator degree of superheat temperature up to 3°C caused an increase in overall refrigeration system efficiency and in the percent of energy saving. The comparison of the optimization results with the actual values of the ethylene refrigeration system, indicates that an increase of about 2 % in overall efficiency of refrigeration system and 22 % in percent of energy saving could be achieved on reducing compressor discharge high pressure, by 8% and on increasing evaporator degree of superheat temperature, evaporator low pressure and condenser degree of sub-cool temperature by 70.5 %, 59 %, and 73 % respectively.

These results give an overall efficiency of 81.8 %, and a percent of energy saving of about 51.18 %.

Main Subjects

Mechanical Engineering

Topics

• Mathematical models
• Algorithms
• Alkanes

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-305518