Debottlenecking procedure of effluent thermal treatment system

In this study pinch technology has been improved for wastewater temperature reduction. Having considered design grouping rules on the basis of pinch technology, a new debottlenecking procedure for thermal treatment of the wastewater network, has been introduced. In the presented procedure, better thermal treatment of effluent network using the new method can be used to avoid investment in new cooling tower capacity and to improve the performance of the tower in a systematic way. Related coding in Visual Sudio.Net 2003, C++, has been developed for the illustrative example to get optimal values in the cooling water design method computations.     

Heavy metal pollution associated with mining activity in the Kouh-e Zar region,NE Iran

The Kouh-e Zar mining area is located in the central part of the “Khaf–Bardaskan” volcanic-plutonic zone, NE Iran. Mining activity has resulted in pollution of soil and water resources by potentially toxic elements including arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), antimony (Sb), nickel (Ni) and zinc (Zn). In this study, the major source of heavy metal pollution and elucidating the probable environmental risks associated with this area were determined by quantifying pollution in soils and water resources. Concentrations of Cd, Cr, Cu, Pb and Zn in the Kouh-e Zar mining area varied in the range of 5–470, 33–442, 25–5125, 81.15–12,096.27 and 55–4210 mg/kg, respectively. The geo-accumulation index for Cd in all samples was extremely high (I_geo > 5) and the enrichment factor also shows an extremely high amount (EF > 40), both representing evidence for highly polluted soil in the area. However, the coefficients of aqueous migration (K_x) of Cd, Cr, Cu, Pb and Zn were K_x < 0.1, so they are classified as “least mobile and inert” grade. Also, the heavy metals tend to remain in soil (solid environment). Cluster analysis (CA) determined the lithogenic origin for Zn, Cu, Cr and Cd, and the anthropogenic origin (mining activity) for Pb in the soils of the mining area. The concentrations of Cd, Cu, Pb and Zn in water are controlled by free Fe and Mn oxy-hydroxide content in the soils. Both water–rock interaction and mining activity have contributed to pollution in the area.

     

Simultaneous optimization of CO2 emissions reduction strategies for effective carbon control in the process industries

Concerns about global warming have led governments to regulate CO₂ emissions, including through emissions caps, trading and penalties, thus creating economic incentives to reduce CO₂ emissions. This paper presents a mathematical model based on a MINLP formulation to address the problem of CO₂ emissions from large-scale sites in the process industries. The proposed approach considers the interactions between process units, associated heat exchanger networks and the site utility system. The CO₂ emissions reduction strategies considered include retrofit of heat exchanger networks (HENs), operational optimization of the utility system and fuel switching. The mathematical model captures interactions between the HEN and the utility system; the optimization explores these interactions systematically within a superstructure of CO₂ reduction options. The optimization objective is to determine suitable CO₂-mitigation options for a given emissions reduction target and available capital for investment, taking carbon trading issues into account. The proposed approach is applied to a published industrial case study; the results demonstrate the applicability of the approach to finding cost-effective solutions for CO₂ emissions reduction. Results show that the best solution CO₂ emissions reduction is affected by carbon trading. Therefore, opportunities to sell CO₂ allowances, if practically achievable, play an important role in the process economics.     

Techno-economic optimization of IGCC integrated with utility system for CO2 emissions reduction—Maximum power production in IGCC

Environmental legislation, with its increasing pressure on the energy sector to control greenhouse gases, is a driving force to reduce CO₂ emissions. In this paper, pre-combustion CO₂ capture through integration of a site utility system with an integrated gasification combined cycle (IGCC) is investigated as an option to provide a compressed CO₂-rich stream from a process site for sequestration. This work presents a two-step procedure for integration and optimization of a site utility system with an IGCC plant: (i) screening and optimization of IGCC plant performance parameters; (ii) integration and optimization of the utility system of the site with the IGCC plant. In the first step, an optimization approach applies the results of screening studies based on rigorous simulation of the IGCC. Having fixed the inlet fuel flow rate, the IGCC design parameters (including oxygen consumption, diluent flow rate and turbine exit pressure) are optimized for maximum power generation. Energy flows between the IGCC and CO₂ compression train are considered. In the second step, the economic and operating performance of the utility system integrated with the IGCC plant are modeled and optimized for minimum operating cost to find the most appropriate level of integration. In a case study illustrating the approach, 94% of the fuel is gasified; additional power generation offsets the operating costs of pre-combustion CO₂ capture.     

Distribution of the interstitial cells of Cajal in the human anorectum

The interstitial cells of Cajal are proposed to have a role in the control of gut motility. The aim of this study was to establish the distribution of interstitial cells of Cajal in the wall of the normal human anorectum. Interstitial cells of Cajal express the proto-oncogene c-kit. Interstitial cells of Cajal were identified in the colon by immunohistochemical staining, using a rabbit polyclonal anti-c-kit antibody. Anorectal tissue was obtained at surgical resection for carcinoma of the colorectum. Density of interstitial cells of Cajal was graded. Statistical analysis was performed using chi2 tests. In the longitudinal and circular muscle layers of the rectum interstitial cells of Cajal were seen in the bulk of the muscle layer. In the intermuscular plane interstitial cells of Cajal encased the myenteric plexus. Interstitial cells of Cajal were found at the inner margin of the circular muscle and in association with neural elements of the submuscular plexus. Within the internal anal sphincter interstitial cells of Cajal were infrequently scattered among the muscle fibres. The density of interstitial cells of Cajal in the internal anal sphincter was significantly lower than that observed in the circular muscle layer of the rectum (P = 0.014). In conclusion, interstitial cells of Cajal are evenly distributed in the layers of the muscularis propria of the rectum, but have a lower density in the internal anal sphincter.     

Application of ozone treatment and pinch technology in cooling water systems design for water and energy conservation

Re‐circulating cooling water systems offer the means to remove heat from a wide variety of industrial processes that generate excess heat. Such systems consist of a cooling tower and a heat‐exchanger network that conventionally has a parallel configuration. However, reuse of water between different cooling duties allows cooling water networks to be designed in a series arrangement. This results in performance improvement and increased cooling tower capacity. In addition, by the integration of ozone treatment into the cooling tower, the cycle of concentration can be increased. The ozone treatment also dramatically reduces the blow‐down that, in turn, is environmentally constructive. In this study, a new environmental‐friendly and cost‐effective design methodology for cooling water systems was introduced. Using this design methodology, Integrated Ozone Treatment Cooling System (IOTCS), achievement of minimum environmental impacts and total cost were afforded through a simultaneous integration of the cooling system components using an ozone treatment cooling tower and optimum heat‐exchanger network configuration. Moreover, in the proposed method, the cooling tower optimum design was achieved through a mathematical model. The IOTCS design method is based upon a complex design approach using a combined pinch analysis and mathematical programming that provides an optimum heat‐exchanger configuration while maximizing water and energy conservation and minimizing total cost. Related coding in MATLAB version 7.3 was used for the illustrative example to obtain optimal values in the IOTCS design method computations. The results of the recently introduced design methodology were compared with the conventional method. Copyright © 2009 John Wiley & Sons, Ltd.     

Sequence stratigraphy of the petroliferous Dariyan Formation (Aptian) in Qeshm Island and offshore (southern Iran)

After sea level rises during the Early Cretaceous,upper parts of the Khami Group sediments(Fahliyan.Gadvan.and Dariyan Formations) deposited over Jurassic sediments.The Lower Cretaceous(Aptian) Dariyan Formation(equivalent to the Shu'aiba Formation and Hawar Member of the Arabian Plate) carbonates,which have hydrocarbon reservoir potential,form the uppermost portion of the Khami Group that unconformably overlays the Gadvan Formation and was unconformably covered by the Kazhdumi Formation and Burgan sandstones.Detailed paleontological.sedimentological.and well log analysis were performed on seven wells from Qeshm Island and offshore in order to analyze the sequence stratigraphy of this interval and correlate with other studies of the Dariyan Formation in this region.According to this study,the Dariyan Formation contains 14 carbonate lithofacies,which deposited on a ramp system that deepened in both directions(NE—wells 5,6 and SW—wells 1,2).Sequence stratigraphy led to recognition of 5 Aptian third-order sequences toward the Bab Basin(SW—well 1) and 4 Aptian third-order sequences toward Qeshm Island(NE—wells 5and 6) so these areas show higher gamma on the gamma ray logs and probably have higher source rock potential.Other wells(wells 2-4 and 7) mainly deposited in shallower ramp systems and contain 3 Aptian third-order sequences.On the other hand,rudstone and boundslone lilhofacies of studied wells have higher reservoir potential and were deposited during Apt 3 and Apt 4 sequences of the Arabian Plate.The Dariyan Formation in Qeshm Island(well 6) and adjacent well(well 5) was deposited in an intrashelf basin that should be classified as a new intrashelf basin in future Aptian paleogeographic maps.We interpret that salt-related differential subsidence,crustal warping.and reactivation of basement faults of the Arabian Plate boundary were responsible for the creation of the intrashelf basin in the Qeshm area.