Sharif Digital Repository

The Natural Gas Liquids (NGL) recovery unit is one of the processes that requires cooling. The sweetened gas enters this unit after the dehydration stage, and the final product called NGL Product is stored and ready for consumption or export. In this research, the first, one of the NGL units, is simulated with HYSYS software. Three types of processes with different cooling systems are studied using the exergy analysis method. Joule-Thomson's combination with the expander is selected for its high exergy efficiency, and the exergy efficiency function has been selected as the objective function 1 to optimize this process mathematically based on this study's findings. The critical term in this... 

Calendula alata, Amaranthus chlorostachys and Chenopodium album plants were tested for their potential to uptake and accumulate stable cesium and lead from solutions in a period of 15 days. The plants were grown hydroponically and placed in solutions containing CsCl and Pb(C2H3O2)2 at three different concentrations (0.6, 2 and 5 mg L-1). Cs transfer factors in different solutions were more than 1 with the highest level of 2.45 for 2 mg L-1 of CsCl and Pb(C2H3O2)2 in mixed solution. According to its uptake from the environment, cesium effect on anatomical and ontogenical structure of plant was studied. Aerial organs of Chenopodium album were investigated for modifications studies. Observation... 

In this paper, thermal and catalytic hydrocracking of liquid paraffin hydrocarbons, from Tehran refinery, is studied using a pilot plant reactor. The experimental system consisted of a vertical tubular flow reactor where hydrogen and liquid products were fed from the top of the reactor and after passing through a bed of catalyst (or quartz beads in the case of thermal hydrocracking experiments), the liquid and gaseous products were separated and sampled for subsequent analyses. The reaction temperature was in the range of 410-430°C for catalytic hydrocracking and 440-470°C for thermal hydrocracking experiments. The space velocities for both sets of experiments varied between 0.5 to 1.5... 

Ethylene oxide production units are among the most dangerous plants in the petrochemical industry. A detailed consequence analysis for different accidental scenarios for a storage tanks in a petrochemical complex in Iran is put forward. Credible scenarios were selected and all the effective factors that may influence the mechanism of release and dispersion of toxic materials were surveyed. Simulator software and numerical models were used to simulate the distribution of toxic material around the leak source. The results can be used in risk management and in providing an emergency response plan to counter unwanted situations in the plant. This is an abstract of a paper presented at the 7th... 

Power plant successful operation is always a function of its constituent sub-systems and components. Due to the current financial constraints in power industry, power plant operators are continuously facing a wide range of challenges when dealing with maintenance scheduling and asset management practices of the plant sub-systems. Knowledge on the roles and criticality of the constituent components on the plant overall performance will help in establishing the plans for its smooth, safe, and economic operation. To ensure making the techno-economical decisions on the maintenance of power plant equipment, this paper focuses on the reliability modeling of the combined cycle power plants (CCPP).... 

The study of salt tolerance mechanisms in halophyte plants can provide valuable information for crop breeding and plant engineering programs. The aim of the present study was to investigate whole transcriptome analysis of Aeluropus littoralis in response to salinity stress (200 and 400 mM NaCl) by de novo RNA-sequencing. To assemble the transcriptome, Trinity v2.4.0 and Bridger tools, were comparatively used with two k-mer sizes (25 and 32 bp). The de novo assembled transcriptome by Bridger (k-mer 32) was chosen as final assembly for subsequent analysis. In general, 103290 transcripts were obtained. The differential expression analysis (log2 FC > 1 and FDR < 0.01) showed that 1861... 

One of the most important issues in planning the reservoir type of Medium Hydro-Power Plants (MHPP) is to determine the optimal installation capacity of the MHPP and estimate its optimal annual energy value. In this paper, a method is presented to calculate the annual energy. A computer program has been developed to analyse energy calculation and estimation of the most important economic indices of an MHPP using the sensitivity analysis method. Another program, developed by Matlab software, calculates the reliability indices for a number of units of an MHPP with a specified load duration curve using the Monte Carlo method. Ultimately, comparing the technical, economic and reliability indices... 

In this paper, exergy analysis of a steam power plant located in southern Iran named Zarand power plant has been studied. In order to optimize the performance of the Rankine cycle and achieve higher exergy efficiency, several parameters have been considered as decision variables. Knowing that there is the ability to change some of the parameters in the specific range in the process of electricity production in power plant, temperature and output pressure of the boiler and output pressure of four steps of extraction turbine have been selected as six decision variables. Also, exergy efficiency has been considered as the objective function. For this purpose, the exergy efficiency of the system... 

Purpose: Does the long-term growth rate of a firm increase by exporting? If yes, how large is that increase in a developing economy? The paper aims to discuss this issue. Design/methodology/approach: The authors incorporate data from the manufacturing plants in Iran as a developing economy for 2003–2011 to address this question. Using fixed effect panel and propensity score matching method, the authors examine whether exportation can affect a firm’s growth rate to test for the learning to grow hypothesis. Findings: The findings document that: not only the exporters are larger and more productive than non-exporters, but they also grow faster in size and productivity measures as well.... 

Anthropogenic activities have added a large amount of heavy metals to the environment. Heavy metal contaminants affect the physiological and biological properties of soil and plant health. Zinc (Zn) is an essential micronutrient and it promotes plant growth and development but a higher concentration of the metal causes reduction in plant growth. The present study was aimed to evaluate the response of Bacillus cereus on maize plants at different concentrations of ZnSO4 (20, 40 and 60 mg kg–1) amended in the soil under pot experiment conditions. The experiment was conducted by using complete randomized design (CRD) with three replications. Higher doses of ZnSO4 inhibited maize growth and... 

Virtual power plant (VPP) aggregates the capacity of diverse distributed energy resources (DERs) dispersed around the network and creates an individual operating portfolio from the composition of DERs characteristics. VPP can schedule the DERs to provide energy and different types of reserve services in order to trade in wholesale electricity markets or provide network services. In this chapter, an optimization model of VPP to provide energy and reserve is addressed. In this regard, diverse DERs’ energy and reserve models are mentioned and optimization models of VPP to aggregate DERs in order to provide energy and reserve and make profit in wholesale markets are regarded. Furthermore, a... 

Virtual power plant (VPP) aggregates the capacity of diverse distributed energy resources (DERs) dispersed around the network and creates an individual operating portfolio from the composition of DERs characteristics. VPP can schedule the DERs to provide energy and different types of reserve services in order to trade in wholesale electricity markets or provide network services. In this chapter, an optimization model of VPP to provide energy and reserve is addressed. In this regard, diverse DERs' energy and reserve models are mentioned and optimization models of VPP to aggregate DERs in order to provide energy and reserve and make profit in wholesale markets are regarded. Furthermore, a... 

In order to generate adequate electricity energy, conventional power plants utilize dramatic volume of water resources. Different methods such as replacing cutting-edge technologies of facilities have been proposed to diminish water consumption in this industry. Most of the approaches are considered as medium or long-term solution which requires substantial investment costs. Meanwhile, because of the process and technology, natural gas-fired power plants need less water among conventional power plants. Therefore, shifting unit commitment planning toward these power plants would aid to save water consumption. Nevertheless, overlooking combined cycle power plants can perform negative impact on... 

This study attempts to examine the natural gas fired power plants in Iran. The required data from natural gas fired power plants were gathered during 2008. The characteristics of thirty two gas turbine power plants and twenty steam power plants have been measured. Their emission factor values were then compared with the standards of Energy Protection Agency, Euro Union and World Bank. Emission factors of gas turbine and steam power plants show that gas turbine power plants have a better performance than steam power plants. For economic analysis, fuel consumption and environmental damages caused by the emitted pollutants are considered as cost functions; and electricity sales revenue are... 

In this paper, the effect of different parameters of power plants, such as height above sea level, performance, ambient temperature, fuel type on emissions in Iran's power plants is investigated. Based on that, a general strategy for selecting the type of power plant, fuel that fit with the geographical situation in the Middle East is presented. Results taken from this scientific study shows that using natural gas to generate power in the region should be a priority. As well as expected, the value of various emission factors decrease by increasing power produce. Also the emission factors of combined cycle power plants are the lowest as compared to other types of power plants  

The first control action in power system restoration concerns the generation restart. In the initial phase of restoration, operators are often concerned with load pickup problems. One of the important problems during load pickup is keeping frequency response in allowable range. The aim of this paper is to determine the best sequence of load pickup by hydro and steam units during power system restoration based on frequency response of prime movers. Hydro power plants and combustion turbine units have the capability of black start operation and can be used for early stages of power system restoration. This paper considers hydro power plants for evaluating the stability and frequency response... 

Meanwhile with increasing demand for energy sources in the world, hydropower plants can be considered as clean energy sources for sustainable development. Hydropower plant environmental impact is almost none. They are easy to construct and operate with much lower cost in comparison with other types of power plants. Currently in Iran, Conventional methods for determining hydropower plant potent location are very complicated and do not always eventuated to the best result. This study focuses on run of river projects and proposes a new methodology to spot hydropower plan best location according to specific engineering criteria, using ArcGIS and an algorithm developed in MATLAB. An economic... 

Load-frequency control is the intrinsic function of the governor in the power plants. It would be used in variant structures depend on the controller type such as PID, adaptive, fuzzy or robust. Temporary droop structure governor (TDSG) was commonly used in Hydro power plants (HPP). After representation of TDSG, this paper is dedicated to introducing a procedure for tuning TDSG parameters. The technique is based on pole placement for the closed loop poles of the system. These poles correspond to the TDSG parameters that by accurate tuning of them, pole placement is accomplished. The results for tuning TDSG of Abbaspour HPP have been presented as well. © 2008 IEEE  

In this paper, inspired by a gas turbine power plant, the interaction between plant-soil processes has been simulated. It is aimed to indicate that solar energy in the photosynthesis process is equivalent to the fuel in combustion chambers. In the glucose production process, when solar exergy is considered as a fuel, 99.4% of total exergy cost is supplied by solar exergy and only 0.6% of the exergy cost is provided by nutrients’ content. In general, 30% of the total exergy entering the Calvin cycle is consumed in glucose production and the remaining 70% is related to biomass generation (as flue gas in the gas turbine). Moreover, 98% of the total exergy cost of the soil box is related to...