Years Of Plant Operation Research Articles

Improving the Economic Efficiency of Heat Pump Integration into Distillation Columns of Process Plants Applying Different Pressures of Evaporators and Condensers

The electrification of process industries is one of the main challenges when building a low-carbon society since they consume huge amounts of fossil fuels, generating different emissions. Heat pumps are some of the key players in the industrial sector of the carbon-neutral market. This study proposes an approach to improve the economic feasibility of heat pumps within process plants. Initial energy targeting with grand composite curves was used and supplemented with the detailed design of an evaporator and a compressor for different condensation and evaporation pressures. The trade-off between the capital cost of the heat pump and the electricity cost was investigated, and optimal configurations were selected. This case study investigates the gas fractioning unit of a polymer plant, where three heat pumps are integrated into distillation columns. The results demonstrate that the heat recovery is 174 MW and requires an additional 37.9 MW of electricity to reduce the hot utility by 212 MW. The selection of the evaporation and condensation pressures of heat pumps allows 21.5 M EUR/y to be saved for 7 years of plant operation. The emission-saving potential is estimated at 1.89 ktCO2/y.

Numerical Modeling and Economic Analysis of Ultrasonic-Assisted CO2 Absorption Process for Offshore Application

In the quest for net zero carbon emissions by 2050, Carbon Capture Utilization and Storage (CCUS) is indispensable. The development of more efficient CO2 capture processes is essential. High-frequency ultrasonic irradiation is an emerging, intensified technique that can enhance the CO2 absorption process. To advance this technology toward commercialization, it is crucial to conduct a thorough economic analysis to allow the identification of the key cost component. While equipment sizing is essential in this economic assessment, there is a lack of numerical models for estimating the size and power consumption of ultrasonic absorbers. This study introduces a numerical model for these predictions. The model was then used to determine the economic feasibility of this emerging technique against the packed bed columns based on capital expenditure (CAPEX), operational expenditure (OPEX), and unit technical cost (UTC) for 20 years of plant operation. According to the economic analysis, ultrasonic intensification requires 34% less CAPEX due to its compact design. Although its OPEX is 11% higher due to the additional electricity needed for the ultrasonic transducers, the UTC is still 3% lower than the conventional packed bed column, demonstrating a potential cost savings in implementing the ultrasonic irradiation-assisted technique during the CO2 absorption process offshore.

ISO 50001 Data Driven Methods for Energy Efficiency Analysis of Thermal Power Plants

This paper proposes an energy management system based on an Artificial Neural Network (ANN) to be integrated with the standard ISO 50001 and aims to describe the definition and the enhancement of the energy baselines by means of artificial intelligence techniques applied and tested on the real electrical absorption data of the auxiliary units of different thermal power plants in Italy. Power plant optimized operations are important both for cost and energy performance reasons with related effects on the environment in the next future energy transition scenario. The improvement of the energy baselines consists in determining more accurate consumption monitoring models that are able to track inefficiencies and absorption drifts through data analytics and Artificial Intelligence. Starting from the analysis of the energy vectors at the production site level, we performed a multi-scale analysis to define the consumption at macro areas level and finally find the most relevant consumption units within the plants. A comparison of different ANNs applied to several real power plant data was performed to model complex plant architecture and optimize energy savings with respect to pre-set thresholds according to the ISO 50001 standard procedure. The energy baselines are determined through the analysis of the data available in the power plants’ Distributed Control System (DCS), and we can identify the consumption derived from the unit’s proper operation. Based on the reported numerical simulations, improved baselines have been reached up to a 5% threshold for different plant sub-units, thus representing a relevant overall saving in terms of alert threshold definition and related control efficiency: a potential saving of about 140 MWh throughout the considered three-year dataset was obtained taking into account a cooling tower sub-unit, representing a considerable economic benefit. The results obtained highlight the neural technique efficiency in defining more accurate energy baselines and represents a valuable tool for large energy plant asset management to face relevant energy drifts observed in the last years of plant operation.

Comparative design-point and yearly advanced exergoenvironmental analyses of a solar-biomass organic Rankine cycle power plant

ABSTRACT This study compared the results of advanced exergoenvironmental analysis at the design point and over a year of operation of a solar-biomass organic Rankine cycle (ORC) power plant based on a real 630 kW ORC plant operational at Ottana (Italy). Although the advanced exergoenvironmental method is now popular in the literature for energy system analysis, it is commonly applied at a single design point. It is, however, not clear yet if such design-point analysis would be acceptably reliable in transient energy systems that depend on varying weather conditions such as solar, a research gap this study attempted to fill. Total impact rates of 7.02 Pts/h were obtained in the hybrid plant at the design point out of which about 4.39 Pts/h is avoidable; 3.50 Pts/h (about 80%) due to the internal operations of each of the individual plant components (endogenous) and 0.89 Pts/h (about 20%) due to interconnections among the system components (exogenous). Also, total yearly impact rates of 91.14 kPts/year were obtained out of which about 69.93 kPts/year is avoidable; 51.13 kPts/year (about 73%) endogenous and 18.80 kPts/year (about 27%) exogenous. While about 63% of the total hybrid plant’s impact rates are obtained avoidable based on the design-point advanced exergoenvironmental analysis, about 76% is obtained in the yearly analysis. These results imply that applying the advanced exergoenvironmental method to a transient energy system over a year of plant operation would offer significantly different insights relative to the analysis at the design point. Going forward, results of the advanced exergoenvironmental method should be interpreted with caution when applied at single design points, especially for energy systems that rely heavily on intermittent weather parameters for their nominal operation.

Innovative hybrid waste to energy–parabolic trough plant for power generation and water desalination in the Middle East North Africa region: Jordan as a case study

This research proposes a hybrid system consisting of a parabolic trough solar field coupled with a waste incineration facility to produce power and desalinated water in Jordan. To predict the performance of the proposed system, EBSILON Professional (13.02) was used to simulate the entire system and for a more realistic simulation process, a prime sample of 100 tons of municipal waste from Jordan was obtained, processed, and homogenised, after which 4 kg was brought to Germany for laboratory analysis. The laboratory results were inserted into EBSILON. Solar radiation data were adapted from meteonorms and input to EBSILON. Heat transfer between the receiver wall and the heat transfer fluid was analysed to calculate the time required to increase the temperature of the Heat Transfer Fluid from the influent temperature to the desired effluent temperature. The results show that this system can produce 34 MWe of power and 13,824 m3/d of distilled water. On the 1st January, the temperature of the heat transfer fluid in the solar field was increased by 6 °C for 20 min in an open cycle. After 5h, it reached 390 °C in a closed cycle, assuming a fixed direct normal irradiance. Economically, five scenarios were analysed to assess the impact of the cost of heat harvested to produce this amount of water on the annual cost of handling each ton of garbage which was approximately 57 US$ in the first year of operation and 19.5 US$ in the 15th year of plant operation (for the scenario in which the tariff of power sales was considered to evaluate the cost of heat for water desalination).

Indirect methyl acetate production process based on dimethyl ether using seed-derived ferrierite from shale gas

Shale-gas-derived methyl acetate (MA) production is an energy-efficient value-added chemical process. Therefore, we first simulated dimethyl ether (DME) production process from shale-gas-derived syngas (CO/H2) by controlling the syngas composition using a membrane separation process and then converted the resulting DME into MA as a proof-of-concept strategy. Our proposed integrated MA synthesis process consisted of syngas production (including Matrimid® 5218 membrane separation), DME production/separation (Cu–ZnO–Al2O3/ferrierite catalyst), and MA production/separation (FER@FER catalyst). In addition, the DME-based MA yield and selectivity were determined using a fixed-bed reactor, and the results were applied to the Aspen PlusTM simulator to describe the overall MA production process from shale-gas. Our proposed MA production process enabled continuous MA production from shale gas and simultaneous H2 production. Furthermore, the proposed catalyst increased MA selectivity to 97% and exhibited relatively high conversion (27.82%) of DME to MA in excess CO. Most importantly, our rigorously mathematically modeled technoeconomic analysis (TEA) estimated that the MA production costs were approximately 0.71, 0.64, 0.60, and 0.63 $/kg MA for dry reforming of methane, partial oxidation, steam reforming of methane, and tri-reforming of methane syngas production methods, respectively. The net present values (NPVs) of the respective processes were 617, 525, 667, and 835 MM$ during 30 years of plant operation. Such low MA production costs and relatively high NPVs were comparable to those of the most mature conventional MA production processes (0.95 $/kg MA) owing to enhanced membrane-separation-based DME production and selective recycling streams, thereby supporting the feasibility of industrially producing MA using syngas-derived DME intermediates.

Economic Effect of Dust Particles on Photovoltaic Plant Production

The performance of photovoltaic panels decreases depending on the different factors to which they are subjected daily. One of the phenomena that most affects their energy production is dust deposition. This is particularly acute in desert climates, where the level of solar radiation is extreme. In this work, the effect of dust soiling is examined on the electricity generation of an experimental photovoltaic pilot plant, installed at the Solar Energy Research Center (CIESOL) at the University of Almería. An average reduction of 5% of the power of a photovoltaic plant due to dust contamination has been obtained, this data being used to simulate the economic effect in plants of 9 kWp and 1 and 50 MWp. The economic losses have been calculated, and are capable of being higher than 150,000 €/year in industrial plants of 50 MWp. A cleaning strategy has also been presented, which represents a substantial economic outlay over the years of plant operation.

Distribution of radiocarbon in sediments of the cooling pond of RBMK type Ignalina Nuclear Power Plant in Lithuania.

The vertical distribution of radiocarbon (14C) was examined in the bottom sediment core, taken from Lake Drūkšiai, which has served as a cooling pond since 1983 for the 26 years of the Ignalina Nuclear Power Plant (INPP) operation using two RBMK-1500 reactors (Russian acronym for”Channelized Large Power Reactor”). 14C specific activity was measured in alkali-soluble and -insoluble fractions of the sediment layers. Complementary measurements of the 210Pb and 137Cs activity of the samples provided the possibility to evaluate the date of every layer formation, covering the 1947–2013 period. In addition, 14C distribution was examined in the scales of pelagic fish caught between 1980 and 2012. Our measurements reveal that, during the period 1947–1999, the radiocarbon specific activity in both fractions exhibits a parallel course with a difference of 5 ± 1 pMC (percent of modern carbon) being higher in alkali-soluble fraction, although 14C specific activity in both fractions increased by 11.4–13.6 pMC during the first 15 years of plant operation. However, during the 2000–2009 period, other than previously seen, a dissolved inorganic carbon (DIC) → aquatic primary producers → sediments 14C incorporation pattern occurred, as the radiocarbon specific activity difference between alkali-soluble and -insoluble fractions reached 94, 25, and 20 pMC in 2000, 2006, and 2008, respectively. Measurements in different sediment fractions allowed us to identify the unexpected organic nature of 14C contained in liquid effluences from the INPP in 2000–2009. The discrepancy between 14C specific activity in fish scales samples and DIC after 2000 also confirmed the possibility of organic 14C contamination. Possible reasons for this phenomenon might be industrial processes introduced at the INPP, such as the start of operation of the cementation facility for spent ion exchange resins, decontamination procedures, and various maintenance activities of reactor aging systems and equipment.

원심펌프의 장기운전에 따른 성능변화 평가

Nuclear power plants have a number of pumps, which are operating at a high temperature–high pressure and radiation environment conditions. However, the aging of the pumps by increasing of years of plant operation and the system transients due to the sudden load change are causing the failures of the reliability of the pumps. Nevertheless, it is important to maintain the reliability of the pumps to ensure safe operation of the nuclear power plant. In this paper, an acceleration test apparatus was developed to secure the reliability of centrifugal pumps. The performance change with the increase of operation time of the pump was experimentally evaluated by the acceleration test. As the operating time of the pump increased, it was confirmed that the pump efficiency and head decreased.

A novel process economics risk model applied to biodiesel production system

Abstract In this paper, the concept of value at risk (VAR) is introduced to study process economics related to biodiesel production and use. Although the VAR concept is actively used in financial engineering for stock investment and trading, it has never been used in process economics. A methodology to develop a VAR model for a biodiesel process facility has been proposed and analysed. The impact of different cost related risk factors is modelled using a stochastic process and interdependence in a Bayesian Network format. The analysis reveals that cost underestimation is the most significant risk factor in biodiesel economics. The VAR model is analysed for 1, 5, and 10 VAR for 5 years of plant operations. Analysing VAR at any point of time (i.e. year 2) shows that with a 1% chance, 5% chance and 10% chance, the maximum loss would be $6.26, $9.52 and $11.34 million respectively (up to year 2). When VAR is considered in the process economics the return period is significantly affected and is increased by 21 months. This study recommends that VAR should be considered as an integral part of process economics, especially for new product or process design.

Thermo-economic evaluation of water-injected air bottoming cycles hybridization using heliostat field collector: Comparative analyses

A possible solution to intermittency and storage difficulties associated with solar energy utilization is power plant hybridization. Additionally, air bottoming cycle is an alternative plant configuration which is more economical for small scale power generation than conventional combined cycle. To further improve the air bottoming cycle thermo-economic performance, water injection in the bottoming cycle air is proposed. In this paper, a detailed thermo-economic optimization is conducted for a hybrid air bottoming cycle power plant with water injection in the bottoming cycle air. Analyses are accomplished by utilizing three thermo-economic assessment approaches comprising levelized cost of electricity, payback period and life cycle savings. The acquired results indicate the advantages of water injection to improve the bottoming cycle heat recovery capability and plant's levelized cost of electricity. Noting that the plant's levelized cost of electricity is improved by 0.7 US$/MWh from 77.8 US$/MWh to 77.1 US$/MWh as water injection in the bottoming cycle is implemented. Therefore, 2.940 MUS$ can be saved during 25 years of plant operation.

Association of systemic lupus erythematosus with uranium exposure in a community living near a uranium-processing plant: a nested case-control study.

To explore the hypothesis that cases of systemic lupus erythematosus (SLE) would be found more frequently in community members with high prior uranium exposure in the Fernald Community Cohort (FCC). A nested case-control study was performed using data from the FCC, a volunteer population of individuals who had resided near a uranium ore-processing plant in Fernald, Ohio during the years of plant operation; uranium plant workers were excluded. Members of the FCC were monitored for 18 years. SLE cases were identified using the American College of Rheumatology 1997 revised classification criteria, laboratory testing, and medical record review. Each case was matched to 4 controls by age, race, and sex. Sera from potential cases and controls were screened for autoantibodies. Cumulative exposure to uranium particulates was calculated using a dosimetry model. Logistic regression with covariates was used to calculate the odds ratios (ORs) with 95% confidence intervals (95% CIs) for the probability of an association between uranium exposure and SLE. The FCC comprised 4,187 individuals with minimal levels of uranium exposure, 1,273 with moderate exposure, and 2,756 with high exposure. The diagnosis of SLE was confirmed in 23 of 31 individuals who had been assigned International Classification of Diseases, Ninth Revision codes for lupus, and was also confirmed in 2 of 43 individuals who had been prescribed hydroxychloroquine. The female to male ratio was 5.25:1. Of the 25 confirmed SLE cases, 12 were in the high exposure group. The presence of SLE was associated with higher levels of uranium exposure (OR 3.92, 95% CI 1.13-13.59; P = 0.031). High uranium exposure is associated with SLE, as compared to matched controls, in this sample of uranium-exposed individuals. Potential explanations for this relationship include possible autoimmune or estrogen effects of uranium, somatic mutation, epigenetic effects, or effects of some other unidentified accompanying exposure.

Performance analysis of a 3 MWp grid connected solar photovoltaic power plant in India

Renewable energy is projected to meet a significant portion of the future energy needs of India. With solar energy, being abundantly available in most parts of the country, grid connected solar photovoltaic (SPV) power plants are assuming increasing importance. Energy fed into the grid by a solar power plant depends upon seasonal variation of the solar resource, losses due to temperature variation, system losses and losses due to condition of the grid. This paper presents performance analysis of a 3MW grid connected SPV plant located in Karnataka State, India as per International Electro-technical Commission (IEC) Standard 61724, using monitored data. Normalised technical performance parameters of the plant are evaluated for the year 2011. Inverter failure losses and grid failure losses are estimated for two years of plant operation. Daily and seasonal variations in the SPV plant output are shown using monitored data at five-minute intervals. The SPV generation in relation to load duration curve of the substation is observed. A comparison of normalised performance parameters of the plant with similar parameters of other plants is given. Annual average energy generated by the plant was 1372kWh per kWp of the installed capacity. Performance of the plant is satisfactory in comparison with that reported from other countries.

A neural network-based preset generation tool for a steel tandem cold mill

This paper traces the development of a software tool, based on a combination of artificial neural networks (ANN) and a few process equations, aiming to serve as a backup operation instrument in the reference generation for real-time controllers of a steel tandem cold mill. By emulating the mathematical model responsible for generating presets under normal operational conditions, the system works as an option to maintain plant operation in the event of a failure in the processing unit that executes the mathematical model. The system, built from the production data collected over six years of plant operation, steered to the replacement of the former backup operation mode (based on a lookup table), which degraded both product quality and plant productivity. The study showed that ANN are appropriated tools for the intended purpose and that by this instrument it is possible to achieve nearly the totality of the presets needed by this kind of process. The text characterizes the problem, relates the investigated options to solve it, justifies the choice of the ANN approach, describes the methodology and system implementation and, finally, shows and discusses the attained results.

Nuclear performance analyses of the HCLL breeder blanket for a fusion power reactor

This paper summarizes results of a neutronic study on the performance of the helium-cooled lithium–lead (HCLL) blanket for a fusion power reactor. The analysis is based on three-dimensional radiation transport calculations with the Monte Carlo code MCNP-4C. The neutronic model based on the PPCS reactor model AB developed by FZK has been used in the analysis. Nuclear performance parameters such as the tritium breeding ratio and the energy deposition rate in the blanket and shield and their radial distributions have been evaluated. The radiation-induced displacement and the helium gas production in the steel structure has been calculated. It was shown that the blanket configuration considered provides TBR greater than the required design value. The gaps between blanket modules was shown to affect the global TBR only insignificantly. The radiation damage assessment has indicated that the HTS could not be designed as a life-time component of the reactor for the anticipated 40 years of plant operation.

Experience gained from operation of the reverse-osmosis plant at the Novosibirsk TETs-2 cogeneration station

We present the main indicators characterizing the performance of the demineralizing plant comprising reverse-osmosis and ion-exchange equipment that produces makeup water for the boilers at the Novosibirsk TETs-2 cogeneration station for three years of plant operation.

Parametric fuzzy study for effects analysis of age on PWR containment cooling system

This paper presents an alternative parametric fuzzy study to subside aging impact analysis on the performance and availability of safety industrial systems. To this sense, a fuzzy fault tree computational system analysis, named of FuzzyFTA, was adopted. FuzzyFTA is a computing system that uses fault tree and fuzzy logic to determine fault event fuzzy importance and associated fuzzy uncertainty measures. The main goal of this approach makes possible, elapsed many years of plant operation, the gray determination of the system critical components and top event occurrence probability. A typical four loops pressurized water reactor (PWR) containment cooling system (CCS) was selected to examine the feasibility of the computational system approach in a real case study. Thus, a commonly found containment spray system and a fan cooler system were modeled. Failure rates, obtained from the operation of a PWR along 20 years, were accounted in the model. The bathtub curve characteristics presents in these failure rates permit the determination of the time-dependent effects of aging degradation more important to the general uncertainty of system. Thus, the system unavailability, considering the component failure rates increase by aging, can be calculated.

MAYAK WORKER DOSIMETRY STUDY: AN OVERVIEW

The Mayak Production Association (MPA) was the first plutonium production plant in the former Soviet Union. Workers at the MPA were exposed to relatively large internal radiation intakes and external radiation exposures, particularly in the early years of plant operations. This paper describes the updated dosimetry database, "Doses-2005." Doses-2005 represents a significant improvement in the determination of absorbed organ dose from external radiation and plutonium intake for the original cohort of 18,831 Mayak workers. The methods of dose reconstruction of absorbed organ doses from external radiation uses: 1) archive records of measured dose and worker exposure history, 2) measured energy and directional response characteristics of historical Mayak film dosimeters, and 3) calculated dose conversion factors for Mayak Study-defined exposure scenarios using Monte Carlo techniques. The methods of dose reconstruction for plutonium intake uses two revised models developed from empirical data derived from bioassay and autopsy cases and/or updates from prevailing or emerging International Commission on Radiological Protection models. Other sources of potential significant exposure to workers such as medical diagnostic x-rays, ambient onsite external radiation, neutron radiation, intake of airborne effluent, and intake of nuclides other than plutonium were evaluated to determine their impact on the dose estimates.

Investigation of CANDU reactors as a thorium burner

Large quantities of plutonium have been accumulated in the nuclear waste of civilian LWRs and CANDU reactors. Reactor grade plutonium can be used as a booster fissile fuel material in the form of mixed ThO2/PuO2 fuel in a CANDU fuel bundle in order to assure reactor criticality. The paper investigates the prospects of exploiting the rich world thorium reserves in CANDU reactors. Two different fuel compositions have been selected for investigations: (1) 96% thoria (ThO2) + 4% PuO2 and (2) 91% ThO2 + 5% UO2 + 4% PuO2. The latter is used for the purpose of denaturing the new 233U fuel with 238U. The behavior of the reactor criticality k∞ and the burn-up values of the reactor have been pursued by full power operation for >∼8 years. The reactor starts with k∞ = ∼1.39 and decreases asymptotically to values of k∞ > 1.06, which is still tolerable and useable in a CANDU reactor. The reactor criticality k∞ remains nearly constant between the 4th year and the 7th year of plant operation, and then, a slight increase is observed thereafter, along with a continuous depletion of the thorium fuel. After the 2nd year, the CANDU reactor begins to operate practically as a thorium burner. Very high burn-up can be achieved with the same fuel (>160,000 MW D/MT). The reactor criticality would be sufficient until a great fraction of the thorium fuel is burned up, provided that the fuel rods could be fabricated to withstand such high burn-up levels. Fuel fabrication costs and nuclear waste mass for final disposal per unit energy could be reduced drastically.

Explosion of auxiliary boiler in an ammonia plant

AbstractThe explosion of an auxiliary boiler occurred in the process of lighting, during plant start‐up. In the 20 years of plant operation, the boiler has been operated in the same way and without any problems. The investigation showed that the explosion happened because the manual valves for burners were not sufficiently closed and that they allowed larger quantities of gas into the boiler; moreover, the dampers were not sufficiently open for air and the flue gas. The installation of firing equipment, made according to the latest revision of relevant and recognized standards, which ensures automatic burner ignition, flame monitoring, and safety control equipment is one of the requirements to avoid boiler explosion. © 2004 American Institute of Chemical Engineers Process Saf Prog, 2004