Search results for "Operating cost"
showing 9 items of 9 documents
Aeration control in membrane bioreactor for sustainable environmental footprint
2020
In this study different scenarios were scrutinized to minimize the energy consumption of a membrane bioreactor system for wastewater treatment. Open-loop and closed-loop scenarios were investigated by two-step cascade control strategies based on dissolved oxygen, ammonia and nitrite concentrations. An integrated MBR model which includes also the greenhouse gas formation/emission processes was applied. A substantial energy consumption reduction was obtained for the closed-loop scenarios (32% for Scenario 1 and 82% for Scenario 2). The air flow control based on both ammonia and nitrite concentrations within the aerobic reactor (Scenario 2) provided excellent results in terms of reduction of o…
Sensitivity analysis and process optimization of a natural gas dehydration unit using triethylene glycol
2019
Abstract Dehydration of natural gas by absorption using triethylene glycol (TEG) is a common industrial offshore procedure to ensure the compliance with the required water dew point specifications for midstream transportation. Two thermodynamic models, the UMR-PRU and the TST/NRTL, are applied for the process simulation while a preliminary economic evaluation has been conducted revealing that both yield overall similar results as for the fixed capital cost which is found to be in good agreement with reported literature values. Moreover, sensitivity analysis of several operational parameters of the process has been performed and optimized values are suggested aiming to reduce its energy requ…
The determinants of net interest income in the Mexican banking system: An integrated model
2009
This paper analyzes net interest income in the Mexican banking system over the period 1993-2005. Taking as reference the seminal work by Ho and Saunders (1981) and subsequent extensions by other authors, our study models the net interest margin simultaneously including operating costs and diversification and specialization as determinants of the margin. The results referring to the Mexican case show that its high margins can be explained mainly by average operating costs and by market power. Although non-interest income has increased in recent years, its economic impact is low. El trabajo analiza el margen de intermediación de la banca Mexicana en el periodo 1996-2005. Tomando como referenc…
Cost modelling for wastewater treatment processes
2011
Abstract The aim of this paper is to provide a methodology for a better understanding of the cost structure of wastewater treatment processes. This methodology may be useful in the planning of new facilities. The existing models in the literature are focused on the influence of the capacity of plant, expressed as inhabitants or flow rate, on the cost of treatment. We propose a new approach for the operating cost function that includes the most representative variables in the process. The idea is that the modelling of treatment costs enables us to understand the key role of the economies of scale in this context; and also the influence of other variables such as contaminants removed, or the …
Evolutionary Design Optimization of an Alkaline Water Electrolysis Cell for Hydrogen Production
2020
Hydrogen is an excellent energy source for long-term storage and free of greenhouse gases. However, its high production cost remains an obstacle to its advancement. The two main parameters contributing to the high cost include the cost of electricity and the cost of initial financial investment. It is possible to reduce the latter by the optimization of system design and operation conditions, allowing the reduction of the cell voltage. Because the CAPEX (initial cost divided by total hydrogen production of the electrolyzer) decreases according to current density but the OPEX (operating cost depending on the cell voltage) increases depending on the current density, there exists an optimal cu…
The operating cost of an anaerobic membrane bioreactor (AnMBR) treating sulphate-rich urban wastewater
2014
The objective of this study was to evaluate the operating cost of an anaerobic membrane bioreactor (AnMBR) treating sulphate-rich urban wastewater (UWW) at ambient temperature (ranging from 17 to 33 degrees C). To this aim, energy consumption, methane production, and sludge handling and recycling to land were evaluated. The results revealed that optimising specific gas demand with respect to permeate volume (SGDp) and sludge retention time (for given ambient temperature conditions) is essential to maximise energy savings (minimum energy demand: 0.07 kW h m(-3)). Moreover, low/moderate sludge productions were obtained (minimum value: 0.16 kg TSS kg(-1) CODRemoved), which further enhanced the…
Model-based automatic tuning of a filtration control system for submerged anaerobic membrane bioreactors (AnMBR)
2014
This paper describes a model-based method to optimise filtration in submerged AnMBRs. The method is applied to an advanced knowledge-based control system and considers three statistical methods: (1) sensitivity analysis (Morris screening method) to identify an input subset for the advanced controller; (2) Monte Carlo method (trajectory-based random sampling) to find suitable initial values for the control inputs; and (3) optimisation algorithm (performing as a supervisory controller) to re-calibrate these control inputs in order to minimise plant operating costs. The model-based supervisory controller proposed allowed filtration to be optimised with low computational demands (about 5min). E…
An Analytic Hierachy Process for Ranking Operating Costs of Low Cost and Full Service Airlines
2009
This paper develops an application of the analytic hierarchy process to rank the operating cost components of full service and low cost airlines. It takes into account the financial balance sheets and answers to a questionnaire submitted to the managers of selected airlines. The results suggest that the analytic hierarchy process can be appropriately used to obtain the ranking of the costs taking into account different views: financial, management and operative. Rental, office equipment and other supplies costs show the highest importance in the cost ranking, both for full services and low cost airlines. The robustness of the results is tested by Monte Carlo analysis.
Quantifying the Potential Economic Benefits of Flexible Industrial Demand in the European Power System
2018
The envisaged decarbonization of the European power system introduces complex techno-economic challenges to its operation and development. Demand flexibility can significantly contribute in addressing these challenges and enable a cost-effective transition to the low-carbon future. Although extensive previous work has analyzed the impacts of residential and commercial demand flexibility, the respective potential of the industrial sector has not yet been thoroughly investigated despite its large size. This paper presents a novel, whole-system modeling framework to comprehensively quantify the potential economic benefits of flexible industrial demand (FID) for the European power system. This …