Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/22876
Title: Synthesis of Work Exchange Networks for Gas Processing Applications
Authors: MD. SHAMSUZZAMAN RAZIB
Keywords: MINLP,optimization,exchangers,LNG,APXTM,simulation
Issue Date: 10-Jan-2011
Source: MD. SHAMSUZZAMAN RAZIB (2011-01-10). Synthesis of Work Exchange Networks for Gas Processing Applications. ScholarBank@NUS Repository.
Abstract: Energy production/usage and its impact on environment are global concerns. Process industries are the major users of energy and plants are increasingly keen on increasing efficiency. To satisfy the increasing demand, several alternatives such as fossil fuels, solar and wind energy, nuclear energy, and bio-energy are being utilized. However, fossil fuels such as Natural Gas (NG), oil, coal, etc. are the most common energy that supplies most of the consumable energy. Among these, NG is the cleanest one vs. environmental damage and converted to Liquefied Natural Gas (LNG) to transport easily and cost effectively. Moreover, surge in market demand, abundance of NG, technological advancement, and environmental concerns force LNG plants to operate under a wide range of operating conditions. As a consequence of their versatility and energy intensive nature, its operations especially compressors in different refrigeration cycles can be far away from the optimal conditions which result in greater energy consumption. This is not only expensive but also less environmental friendly. Therefore, industries are keen to utilize any new technology that is able to reduce the energy consumption while increasing the capacity of the plant. AP-XTM LNG liquefaction system is the latest technology by Air Products to provide refrigeration to NG with much more higher capacity than any other existing technologies for the same purpose. Hence, optimal operations of this process over a wide range of operating conditions not only save money but also ensure less environmental damage. Compressors in different cycles are the major users of energy in this process. For this purpose, we develop a generalized Non-Linear Programming (NLP) model of this process with the objective of minimizing total compressor load using a thermodynamic approach. The model is generalized so that process parameters and variables can be easily adapted to different operating scenarios, enhancing its utility in the area. A set of optimal operating condition can be obtained through this model for each operating scenario such that the LNG facility can be operated at or near its maximum efficiency. Finally, the effectiveness of this approach is demonstrated through different operation scenarios. Although an exact comparison with actual AP-XTM system is not available due to proprietary nature of actual data, the optimized power requirement is found to be competitive with those reported in the literature. As compressors are found to be the preeminent energy consuming equipment not only in LNG plants but also in different chemical plants such as Refineries, Air Enrichment, Ammonia-Urea, etc., optimal synthesis of compression equipment may facilitate the reduction of energy consumed by these plants. In such plants, some process streams may need compression, while others may need expansion. Optimal integration of these streams may yield major savings in energy. Even when streams need compression only, e.g. for natural gas transmission, optimal design and operation of work exchange network is essential. In other words, a synthesis problem analogous to that for a heat exchange network can be defined for work exchange network as well. While a lot of work exists on heat exchanger network synthesis, there is virtually no research on work exchange network synthesis (WENS). In this work, we incorporate realistic work and efficiency correlations as well as thermodynamic effects with a goal to minimize total annualized cost of the network. We employ the concept of superstructure and formulate the entire problem as a mixed-integer nonlinear program (MINLP) while addressing realistic operational constraints for both compressors and turbines. Moreover, a solution strategy is demonstrated to solve this model as commercial solvers are unable to produce better solution. The benefits of this model are illustrated by two case studies.
URI: http://scholarbank.nus.edu.sg/handle/10635/22876
Appears in Collections:Master's Theses (Open)

Show full item record
Files in This Item:
File Description SizeFormatAccess SettingsVersion 
Cover.pdf6.1 kBAdobe PDF

OPEN

NoneView/Download
Spine.pdf6.09 kBAdobe PDF

OPEN

NoneView/Download
Title page.pdf6.4 kBAdobe PDF

OPEN

NoneView/Download
Acknowledgements.pdf25.79 kBAdobe PDF

OPEN

NoneView/Download
Table of contents.pdf27.76 kBAdobe PDF

OPEN

NoneView/Download
Summary.pdf29.43 kBAdobe PDF

OPEN

NoneView/Download
List of Tables.pdf24.94 kBAdobe PDF

OPEN

NoneView/Download
List of Figures.pdf28.03 kBAdobe PDF

OPEN

NoneView/Download
Nomenclature.pdf80.03 kBAdobe PDF

OPEN

NoneView/Download
CHAPTER 1.pdf69.36 kBAdobe PDF

OPEN

NoneView/Download
CHAPTER 2.pdf55.6 kBAdobe PDF

OPEN

NoneView/Download
CHAPTER 3.pdf675.47 kBAdobe PDF

OPEN

NoneView/Download
CHAPTER 4.pdf449.29 kBAdobe PDF

OPEN

NoneView/Download
CHAPTER 5.pdf33.43 kBAdobe PDF

OPEN

NoneView/Download
References.pdf39.48 kBAdobe PDF

OPEN

NoneView/Download

Page view(s)

402
checked on Dec 11, 2017

Download(s)

3,575
checked on Dec 11, 2017

Google ScholarTM

Check


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.