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Organic Rankine cycles (ORCs) have been a mature technology for low temperature waste heat utilization. However, the relatively low thermal efficiency and incomplete waste heat recovery limit the power output of ORC systems. The reason for the above two problems is that the temperature-enthalpy (T-H) profile of waste heat sources does not match well with the organic working fluid in an ORC system...
This paper proposed a mathematical model for formulating interplant heat exchanger network (HEN) operated under multi-periods. Each individual plant is linked through a centralized utility system and steam is selected as the heat transferring medium. Previous studies on optimizing interplant HENs mainly focus on minimizing the cost of system. In this study, the interplant HEN is optimized with two...
This paper presents an energy hub approach for direct interplant heat integration using process streams. An energy hub is a geographical center where all process streams from different plants can integrate. Each stream is only allowed to remain in the heat exchanger networks (HENs) in its original plant or be transported into the energy hub to exchange heat with the streams from other plants. Thus,...
Refinery hydrogen consumers (e.g., hydrocrackers and hydro-treaters) are normally operated at high pressure. The make-up hydrogen and recycle hydrogen compressors are commonly used to increase the pressure of the hydrogen streams. This requires compression work, which can be a major contributor to the operating cost. Therefore, apart from minimizing the flowrate of hydrogen utility, it is also important...
The facility layout design within a plant is a key step in the process of chemical engineering design. A good layout can save capital cost, energy and natural resource. The aim of this work is to determine the relative location of facilities in a large-scale industrial plant considering multi-floor structure to make the total cost minimum. The objective function consists of piping investment cost,...
There is a growing interest in developing Inter-Plant Heat Integration (IPHI) methods for reducing energy consumptions and emissions beyond that of independent plants. However, practical IPHI problems present complexities as boundaries for simultaneous intra- and inter-plant heat integration are considered. Pinch Analysis (PA) can mitigate these complexities by elucidating design insights before developing...
A cooling water system requires a large amount of power to send water to coolers installed at high platform. In spite of pressure drop, most power is not consumed, but turns to potential energy. The potential energy will turn back to pressure once cooling water goes down from high, but the pressure is wasted in current cooling water system. In this work, hydro turbines are used to recover surplus...
It is a challenging task to solve a large-scale Inter-Plant Heat Integration (IPHI) problem, especially for simultaneous optimization for intra- and inter-plant heat integration. In the companion paper (Part I), a novel screening algorithm named Nearest and Largest Qrec-based Screening Algorithm (NLQSA) was proposed. It can be used to divide a large-scale IPHI problem into several small ones, each...
Multi-plant heat integration can be carried out indirectly through intermediate fluids like steam, thermal oil and hot water. Current researches mainly focus on heat recovery aspect and some important factors are not holistically considered, for instance, the parameters of intermediate fluid, interconnectivity patterns between plants and the detailed configurations of multi-plant heat exchanger networks...
In the past decades, the Organic Rankine Cycle (ORC) has become a promising technology for low and medium temperature energy utilization. In refineries, there are usually multiple waste heat streams to be recovered. From a safety and controllability perspective, using an intermedium (hot water) to recover waste heat before releasing heat to the ORC system is more favorable than direct integration...
Fouling is a crucial problem in refinery HEN (heat exchanger network) that reduces heat transfer and affects regular production. The conventional way to mitigate fouling is cleaning heat exchanger regularly or improving operation conditions, but simultaneous consideration of the two methods is rare. This paper presents a combined approach for mitigating fouling in HEN by optimizing operation condition...
Fouling of the inside of tubes in crude oil preheat systems increases pressure drop and pumping costs. In this paper, a method is proposed for optimizing crude oil velocity to reduce fouling of the heat exchanger tubes thereby maintaining heat transfer rates and reducing pressure drop. A simulated annealing algorithm is proposed to describe and optimize the interactions between heat transfer, pressure...
This study proposes a systematic method for targeting the interplant hydrogen network with direct and purification reuse/recycle schemes. The generalized Improved Problem Table is proposed to locate the flowrate targets of individual and interplant hydrogen networks. The constructed limiting composite curves and optimal hydrogen supply lines are utilized to illustrate the insights of the proposed...
Heat Integration across plants is an extension of conventional Heat Integration in a single plant for further improving energy efficiency. To make good use of surplus heat, Indirect Heat Integration method using intermediate fluid loops and Direct Heat Integration method using process streams are proposed to exchange heat across plants. Up to now, the two integration methods are studied separately...
ORC (Organic Rankine Cycles) are widely used in low temperature waste heat recovery which can lead to considerable energy saving. Huge amounts of waste heat need to be cooled to the ambient temperature in refineries. The target temperature of this type of waste heat can be as low as the ambient temperature. The selection of working fluid and operating conditions exert significant influence on the...
Increasingly strict environmental and product-quality regulations coupled with the change of crude oil to high-sulfur and heavier oil have increased refineries' hydrogen demand. Various HNI (hydrogen network integration) methods have been used to achieve efficient use of hydrogen by refineries, leading to reduced energy consumption and cost. However, to minimize the energy consumption of a hydrogen...
Introducing purification devices into hydrogen systems can enhance the extent of hydrogen reuse. However, the economic performance of a purification device depends on its appropriate placement within a hydrogen system. Based on some established graphical methods, this paper explores the influences of the feed concentration on the purification process. A simple and systematic graphical method is proposed...
Centrifugal pumps are widely used in cooling water systems to transport cooling water to its users. They are installed in the header line of the feed pipe, constituting a main pump network. The pressure head of the main pumps must be large enough to satisfy the pressure heads of all coolers. The pressure drop of parallel branch pipes must be balanced by reducing the opening of valves for some coolers,...
Growing hydrogen demands in oil refining are forcing many refiners to optimize their hydrogen distribution networks in order to address the demands without incurring excessive energy consumption, capital investment and operating costs. In addition to the use of hydrogen utility, the foremost consumption of energy is the compression power. In order to express hydrogen consumption and compression power...
Multi-feed multi-product (MFMP) operation is a characteristic and significant trend in the development of novel energy-chemical systems. The complicated characteristics of an MFMP system coupled with multiple materials, energy and information flows are difficult to assess on the basis of conventional thermal indicators. In this paper, a feasible evaluation framework for MFMP systems is proposed. Based...
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