Top-level Analysis of Site Utility Systems

Varbanov, Petar Sabev; Perry, S. J.; Makwana, Yogesh M.; Zhu, Xin; Smith, Robin

doi:10.1205/026387604774196064

Cited by 48 publications

(18 citation statements)

References 5 publications

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“…They cannot be always translated to cost savings via reduction of fuel consumption because the latter is also related to the power import from the grid via the amount of steam generated [11] developed further the Top-Level Analysis methodology using successive operational optimisation to evaluate the marginal steam prices.…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

Utility systems operation: Optimisation-based decision making

Velasco-Garcia

Varbanov²,

Arellano‐García

et al. 2011

Applied Thermal Engineering

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Utility systems provide heat and power to industrial sites. The importance of operating these systems in an optimal way has increased significantly due to the unstable and in the long term rising prices of fossil fuels as well as the need for reducing the greenhouse gas emissions.This paper presents an analysis of the problem for supporting operator decision-making under conditions of variable steam demands from the production processes on an industrial site. An optimisation model has been developed, where besides for running the utility system, also the costs associated with starting up the operating units have been modelled. The illustrative case study shows that accounting for the shutdowns and start-ups of utility operating units can bring significant cost savings.

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Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

Utility systems operation: Optimisation-based decision making

Velasco-Garcia

Varbanov²,

Arellano‐García

et al. 2011

Applied Thermal Engineering

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“…Alternatively, it may lead to steam savings in steam heaters, and a corresponding reduction of cold utility use. It is not obvious how such changes to steam balances due to retrofits within single process units affect the overall fuel and energy balances for an industrial plant [16]. The consequences of reduced steam demand or steam production in one unit on the site steam and fuel balances are further complicated when steam turbines are also used for steam expansion between higher and lower pressure headers, which is often the case for refinery and large petrochemical sites.…”

Section: Introductionmentioning

confidence: 99%

A Steam Utility Network Model for the Evaluation of Heat Integration Retrofits – A Case Study of an Oil Refinery

Marton¹,

Svensson²,

Subiaco³

et al. 2017

J. sustain. dev. energy water environ. syst.

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This paper presents a real industrial example in which the steam utility network of a refinery is modelled in order to evaluate potential Heat Integration retrofits proposed for the site. A refinery, typically, has flexibility to optimize the operating strategy for the steam system depending on the operation of the main processes. This paper presents a few examples of Heat Integration retrofit measures from a case study of a large oil refinery. In order to evaluate expected changes in fuel and electricity imports to the refinery after implementation of the proposed retrofits, a steam system model has been developed. The steam system model has been tested and validated with steady state data from three different operating scenarios and can be used to evaluate how changes to steam balances at different pressure levels would affect overall steam balances, generation of shaft power in turbines, and the consumption of fuel gas.

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“…Neither the process nor utility streams information is available for the process reagent plant technologies to allow either of these approaches to be used in the methodology. Varbanov et al (2004) identified a new procedure that decoupled the low-level system modelling tasks from the high-level system analysis. The high-level stepwise optimisation procedure was used to identify improvements to the utility system through determining the true marginal price of steam at the different pressure levels and the constraints on steam savings imposed by the utility system.…”

Section: Total Site Analysismentioning

confidence: 99%

“…Existing utility systems were investigated and the optimisation objective was to minimise the overall operating costs. While the methodology proposed and used in the thesis took into consideration minimisation of operating cost through its impact on NPV, the optimisation approach used by Varbanov et al (2004) was not considered appropriate as it required a successive mixed-integer linear programming approach.…”

Section: Total Site Analysismentioning

confidence: 99%

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Improving the assessment of process reagent plants and utilities for high temperature hydrometallurgical process plant during early stage project development

Reuter¹

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The current approach taken during the early stages of project development for high temperature hydrometallurgical plants (HTHPs) does not allow time for evaluating process reagent plants or adequately assessing the potential to recover low grade waste heat (LGWH). Therefore, there is a greater risk of making sub-optimal decisions when selecting process reagent plant technology and integrating LGWH recovery into the overall facility design. These decisions have a detrimental impact on energy efficiency and economic outcomes.The primary reason for the lack of integration of process reagents plants -and the related assessment of LGWH available for recovery -lies in the absence of a modified gated project development methodology, including the necessary models, to allow for better decision making in the early stages of project development.A modified project development process has been developed for use from the Scoping Study (FEL-1) stage to Front End Engineering Design (FEL-3). This methodology will allow project design engineers to independently and efficientlyusing minimal effort -evaluate and rank process reagent technologies by plant type and also by combination, for a given set of technical and financial parameters.The methodology includes the use of empirical models for hydrometallurgical plant and process reagent plant prediction, which have been developed based on actual plant design data. The models can cater for different hydrometallurgical plant scopes and a range of plant capacities. The evaluation was undertaken using a purposedesigned, integrated technical and financial model.Case studies based on a nickel laterite flowsheet were developed to demonstrate the evaluation process; the ultimate objective was to select and rank the combinations of process reagent plant technologies. The evaluation also identified how changes in major operating cost inputs affected technology selection.The benefits of applying the developed methodology during Pre-feasibility Study Level (FEL-2) include earlier selection of process reagent plant technology and specification for Front End Engineering Design (FEL-3). As a result, more definitive information is provided for procurement activities. Additionally, this approach Page iii produces an integrated overall plant facility design, maximising the project's economic value and minimising future evaluation effort and potential re-work.The key outcomes from the research were:  Electric power generation of up to 50% of total plant load is potentially available using organic Rankine cycle LGWH recovery technology for the metals plant scope, with corresponding significant greenhouse gas emission reductions. The methodology could be extended to include other material flows such as water, process flow sheets with similar characteristics, and the design and evaluation of suitable engineered multi-component systems. The viability of the recovery of LGWH is improved when included in the early stages of design, as the options can be appropriately assessed in conjunction wit...

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Top-level Analysis of Site Utility Systems

Cited by 48 publications

References 5 publications

Utility systems operation: Optimisation-based decision making

Utility systems operation: Optimisation-based decision making

A Steam Utility Network Model for the Evaluation of Heat Integration Retrofits – A Case Study of an Oil Refinery

Improving the assessment of process reagent plants and utilities for high temperature hydrometallurgical process plant during early stage project development

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