Steam System Network Synthesis Using Process Integration

Self Cite

The traditional steam system comprises a steam boiler and the associated heat exchanger network (HEN). Most research published in literature tends to address both the elements of the steam system as separate entities instead of analyzing, synthesizing, and optimizing the overall system in a holistic manner. True optimality of the steam system can only be achieved if the analysis is conducted within an integrated framework. Process integration has proven to be a powerful tool in similar situations. This paper presents a process integration technique for network synthesis using conceptual and mathematical analysis without compromising boiler efficiency. It was found that the steam flow rate to the HEN could be reduced while maintaining boiler efficiency by utilizing sensible heat from the high pressure steam leaving the boiler. In the event of too little sensible energy being available, a compromise in either minimum steam flow rate or boiler efficiency must be made. A dedicated preheater can also be added to the HEN so as to guarantee the boiler efficiency is maintained; however, this will compromise the minimum steam flow rate. It was found that the flow rate could be reduced by 29.6% while still maintaining the boiler efficiency for an example problem.

Section: Problem Statementmentioning

confidence: 99%

Section: Problem Statementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

On Synthesis and Optimization of Steam System Networks. 1. Sustained Boiler Efficiency

Majozi¹,

Price²

2010

Self Cite

“…The thermodynamic method is generally used to analyze the energy recovery or usage conditions of the steam system in an industry process. Optimization has then focused mainly to increase the energy utilization and exploit the benefit of maximizing process–process integration. − Nishio et al proposed a design method for utility systems. This method is based on the estimation of thermodynamic losses and the irreversibility in the system.…”

Section: Introductionmentioning

confidence: 99%

Modeling and Optimization of a Steam System in a Chemical Plant Containing Multiple Direct Drive Steam Turbines

Zhao

et al. 2014

Steam systems in some of China's chemical plants usually contain multiple direct-drive steam turbines that provide mechanical power to pumps/compressors. When optimizing this system, a certain degree of deviation is found in the theoretical models of steam turbines. A more realistic steam turbine model is developed by improving the traditional thermal model using industry data. This model characterizes efficiency variations under different conditions. Boiler and other unit models are then simplified to allow the use of this model in optimization. By incorporating the models, a mixed-integer nonlinear programming (MINLP) model is formulated to perform the operation optimization. The proposed model considers electric power as the alternative energy source for lower-level mechanical power demands. Using the proposed optimization model on an ethylene plant, a maximum of 8.01% reduction in the total operation cost is achieved compared with the original operation strategies. This case study shows a successful application of the MINLP model in optimizing an actual chemical plant.

“…Gorsek et al presented modified site sink source profiles to determine energy saving potential by integration of existing plant with other plants. The graphical and mathematical techniques for targeting and network synthesis were presented by Coetzee and Majozi to reduce steam flow rate without compromising the duty requirements of the process heat exchangers. Matsuda et al demonstrated improvement in energy savings potential via integration of multiple plants using Total Site Analysis for a group of industries.…”

Section: Introductionmentioning

confidence: 99%

Minimization of Thermal Oil Flow Rate for Indirect Integration of Multiple Plants

Bade

Bandyopadhyay

2014

Energy integration of multiple plants may be carried out indirectly through thermal oil. Flow rate of thermal oil is related to the heat to be transferred, and it affects the capacity and power requirement of the pumps and the piping size. In this paper, a linear programming formulation is proposed to minimize the flow rate of thermal oil. The proposed formulation considers the minimum total utilities requirement for indirectly integrated multiple plants as a constraint. For the special case of two plants integration, a graphical methodology, based on the principles of Pinch Analysis, is also developed. The proposed methodologies are illustrated with examples, and possible heat exchanger networks are developed.