查看更多>>摘要：Safe and efficient operation of the forced-oxidation system is of importance to the wet flue gas desulfurization (WFGD). However, equipment and system failures are commonly found due to the long-time running, frequent blower switching, and heavy workload etc., especially after the ultra-low emission (ULE) renovation to meet strict emission standard in China. This work develops a fault early detection method to improve the predictive maintenance of the forced-oxidation system including blowers, pipes, and the slurry tank. A model based on long short-term memory (LSTM) network and attention mechanism (AM) is constructed to predict real-time operation parameters and compare with the measured values. Then the sequence probability ratio test (SPRT) is utilized to analyze the prediction-measurement residual and provide automatic and dynamic warning. All the data for model training and prediction are from the build-in distributed control system (DCS) without additional sensors. The LSTM-AM model proves to accurately predict time-dependent and highly relevant parameters. SPRT can sensitively perceive the fault-caused residual deviation while alleviating the noises. Industrial application to the cases in a 50 MW combined heat and power generation plant is then carried out. Results show that the bearing failure of the oxidation blower and branch pipes (immersed in the slurry tank) blockage can be forecast in advance when the incipient degradation occurs.
查看更多>>摘要：Produced water (PW) generated worldwide has lately become an issue of environmental concern. PW has a complex composition and a suitable treatment at offshore oil and gas platforms is required to achieve zero harmful discharge into the sea. The feasibility of electrochemical oxidation, heat-activated persulfate and ozonation was investigated as PW pretreatment. For comparison purposes, a common oxidant dosage level of 5% and 10% treatment equivalent chemical oxygen demand(COD) removal were established. Aiming to access PW biodegradability, an assay for biological oxygen demand(BOD) for high salinity matrix was also developed as a tool to characterize treatment efficiency. Electrochemical oxidation was largely independent on the anode materials, and controlled by the applied charge passed through the system. Heat-activated persulfate reaction was time-consuming and dependent on activation temperature, as well as initial oxidant concentration. Both methods reduced COD and BOD without significantly improving PW biodegradability, probably due to by-products generation. Ozonation had the most promising results applying doses ranging from 3.5 to 151mgO3/L The benzene in PW after ozonation reduced up to 71% alongside with >70% toxicity reduction for tested doses. Ozonation also showed to marginally improve PW biodegradability, which underline the potential of ozone to facilitate a subsequent biological treatment.
查看更多>>摘要：The ignition temperature (IT) of the dust cloud is one of the main parameters of combustible dust deflagration risk assessment. Since the previous research focuses on the IT of single dust, in order to reduce the deflagration risk of mixed dust, the effects of dust concentration and dispersed pressure on the IT of wood-plastic mixed dust and the inhibition effects of different powder inhibitors were investigated through experiments. The thermal decomposition behavior of the mixed dust was studied by comprehensive thermal analysis, and the surface characteristics of the deflagration products were analyzed by FTIR spectra, thus revealing the inhibition mechanisms of inhibitors on ignition sensitivity of mixed dust. The results showed that the best ignition conditions for wood-plastic mixed dust were 300 g/m3 and 15 kPa. Ammonium polyphosphate (APP) and aerosil had significant inhibition effects on the ignition sensitivity of wood-plastic mixed dust, and the inhibition effect was better with the increase of inerting ratio. Their inhibition mechanisms are different, and the inhibition effect of APP is better. It was worth noting that APP can promote the initial decomposition of wood-plastic mixed dust, resulting in accelerated dehydration and carbonization rate of mixed dust and improved thermal stability.
查看更多>>摘要：Many accidents occur owing to decision-making failures in accident prevention. From an information perspective, decision-making failures in accident prevention are due to a lack of necessary information. Moreover, the research-practice gap is a long-standing and common problem in accident prevention. To solve the abovementioned problems to improve accident prevention, this study proposes a new accident prevention approach referred to as evidence-based accident prevention. This approach emphasizes the use of the best accident prevention evidence in the accident prevention decision-making process. It is regarded as a practical approach to avoid the lack of safety information to improve the quality of accident prevention decision-making and narrow the research-practice gap vis-a-vis accident prevention. First, this paper explains that evidence-based accident prevention is based on accident prevention failures from a safety information perspective. Second, this study proposes a model for evidence-based accident prevention. Finally, this study applies an evidence-based accident prevention approach to the prevention of hazardous chemical storage accidents in a paint manufacturing plant in Tianjin, China, as a case study. This study aims to help researchers and practitioners to understand the evidence-based accident prevention approach and lay a foundation for the future study and practice of evidence-based accident prevention.
查看更多>>摘要：Biodiesel is currently regarded as a sustainable and renewable alternative to depleting fossil fuels such as petro-diesel. Biodiesel production on a large scale could have a positive impact on the energy sector and the environment by lowering greenhouse gas emissions. Disadvantages of biodiesel include utilization of high-cost edible oils for production of biofuels, generation of wastewater and inability to recycle catalysts after alkaline-catalyzed methanolysis. The objectives of the current study were to utilize low-cost, inedible tallow to produce biodiesel from Lewatit-immobilized lipase produced from Bacillus pumilus and to measure the fuel properties and exhaust emissions of the resulting fatty acid methyl esters. Response surface methodology was used to optimize reaction conditions and alkaline (potassium hydroxide; KOH) catalysis was performed for comparison. A conversion of 96% was achieved by two step chemical-mediated trans-esterification, whereas conversion was 67% for the single step lipase-mediated method. Acid pre-treatment was needed in the case of KOH-catalyzed transesterification to reduce the acid value of tallow from 17.6 to 1.3 mg KOH/g, whereas the Lewatit-immobilized lipase was able to efficiently catalyse both transesterification of glycerides and esterification of free fatty acids. To the best of our knowledge, the lipase from B. pumilus has not yet been studied for biodiesel production from tallow. Fuel properties of the resulting optimized biodiesel were within the limits prescribed in ASTM D6751 and EN 14214. In addition, exhaust emissions studies revealed reduced CO and PM relative to petro-diesel. In both cases, reductions were greater as the percentage of biodiesel increased in blends with petro-diesel. However, NOx emissions were elevated versus petrodiesel in blends that contained 50% or more of biodiesel. This research reveals new ways for utilization of waste animal fats for biodiesel production as well as a new efficient lipase source that yields more products and provides environmental and economic security.
Luciana de Melo PireteFranciele Pereira CamargoGuilherme M. Grosseli
13页
查看更多>>摘要：The optimized removal of the anti-inflammatory drug ibuprofen inoculated with activated sludge biomass in batch reactors was evaluated, using the variables ibuprofen (60-80 ug L-1), ethanol (130-230 mg EtOH L-1) and nitrate (130-230 mg NO3~ L-1) by rotational central compound design. A higher removal efficiency of ibuprofen (97.5 ± 3.1%) was observed with 95.9 mg NO3~-L~(-1), 109.9 ug IBU L'1 and 110.6 mg EtOH If1. Under these conditions, complete removal of NO3~-(1.1 h-1 speed), 20 ± 2.7% of organic matter removal (366.5 ± 3.5 mg COD L-1) >90% ethanol removal were obtained. Based on the mass sequencing of the 16 S rRNA gene via the lllumina platform, bacteria related to the degradation of recalcitrant compounds were identified, such as Pseudomonas (1.5%), Zoogloea (1.73%) and Rhodanobacter (1.63%). The enzymes involved in denitrification were also inferred, such as nitrate transporters and several reductases involved in the conversion of intermediates. Although ibuprofen removal occurred in the absence of ethanol (16.5%) and nitrate (15.2%), the optimal removal range (97.5%) as well as the selection of bacteria possibly involved in its degradation pathways was obtained with 110.6 mg EtOH L-1 and 95.9 mg NO3~-If1, achieving removal approximately 5.9 times higher when compared to the assays without ethanol and nitrate.
查看更多>>摘要：The rising demands of fuel and petrochemical fuels that have harmful gas emissions are encouraging researchers to develop green fuels, especially biodiesel. Whereas the substantial restriction for utilizing biodiesel as a replacement fuel is poor cold flow properties. This research aimed to consider the synchronic improvement of canola biodiesel-diesel-alcohols mixture with low-temperature performance and diesel engine parameters. The simplex lattice mixture design method was applied to optimize, statistically analyze, and design fuel-blend experiments. The best-fitted values via the models were verified employing analysis of variance. Optimum conditions for the cold flow properties of the ternary fuel blends were achieved at biodiesel (19.3), diesel (41.7), and alcohol (39) v/v.%, named as B19.3-Bu39. At the optimum, the best cold flow properties had a pour point and cloud point of-22.67 and-16.37 °C. Engine performance results revealed that increment of higher alcohols in fuel blend enhanced brake specific fuel consumption (6.22%) and exhaust gas temperature (16.25%), while the brake thermal efficiency (4.03%) diminished. At the maximum loading, emission reductions of 13% and 49% of carbon monoxide, and 20.3% and 30.5% of un-burned hydrocarbon were achieved for B19.3 and B100 (100% biodiesel). Oxidative stability of the optimum fuel blend was 10.32 h, which is satisfactory according to EN14214 standard. Results implied that the B19.3-Bu39 fuel has superior lubrication, lower emission, wear, and friction as compared to pure diesel. It can be concluded that the incorporation of higher alcohols presents a novel prospect for the simultaneous improvement of fuel cold flow properties and CI engine operability parameters.
查看更多>>摘要：Due to the high available and reliable requirements of petrochemical processes, it is critical to develop realtime fault detection approaches with high performance. Some machine learning approaches have shown good results but the learning process is too complicated to meet the requirements of online application, such as plenty of samples or the laborious hyper-parameter optimization is needed. In this paper, a fault detection approach based on space-time compressed matrix (STCM) and Naive Bayes (NB) is proposed to realize the fast learning and prediction. First, the slowly varying features which reflect the inherent dynamic information of petrochemical processes are extracted by slow feature analysis. Second, the accumulative importance of slow features and the reconstructive advantage of slow feature under-sampling are proposed to achieve the space-time compression of data matrix. Finally, the STCM is employed to establish the NB model, which can significantly reduce the learning complexity while ensuring classification performance. Experiments on the Tennessee Eastman benchmark show that the proposed approach reduces the sample-size and feature-size by 75% and 92% respectively. Both the average classification accuracy and Fl score on 21 faults exceed 84%, achieving the state-of-the-art results among the comparative approaches.
查看更多>>摘要：To realize utilization of agricultural and plastic waste to alleviate environmental pollution, the individual pyrolysis and co-pyrolysis characteristics of kidney beans stalk (KS) and high-density polyethylene (HDPE) were investigated. Thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) was used to investigate the pyrolysis behaviour, synergistic effect, kinetics and gaseous product evolution of different samples. In addition, an artificial neural network (ANN) model was established to predict the mass change with temperature during sample pyrolysis or co-pyrolysis. The results showed that the decomposition of HDPE was easier than that of KS, and synergistic and inhibitive effects occurred during co-pyrolysis. The synergistic or inhibitive effect was most significant from 470 to 510 °C. The FTIR analysis results showed that gaseous products of KS pyrolysis were mainly oxygen-containing compounds including CO2, CO, ketones, aldehydes, esters, etc., while those of HDPE pyrolysis were mainly hydrocarbons including alkanes, alkenes, aromatic rings, etc. The co-pyrolysis of samples with different proportions promoted or inhibited the production of some gaseous products to different degrees. Moreover, the activation energy of the two stages during co-pyrolysis was lower than that of the pure sample. The established ANN model can effectively predict the mass loss of a sample with temperature.
查看更多>>摘要：In this study, the mixture of two compost materials, including Yard Waste and Leaf Compost (YWLC) and Biosolids Compost (BSC) was optimized for methane (CH4) oxidation to be suitable for a field-scale landfill biocover. Laboratory column tests were conducted with CH4 and carbon dioxide (CO2) flowing through the column at 50:50 v:v to assess the CH4 oxidation in the vertical profile of the compost. The variation in CO2:CH4 ratio, indicating methanotrophic activity, was assessed during three column trials considering two different mixing ratios of 1:1 and 1:4 YWLC:BSC, moisture contents (MC) of 60%, 35%, and 40% ww, and the addition of a methanotroph-enriched compost extract. It was found that the main restricting factors for effective CH4 oxidation were high MC, Exopolymeric Substance (EPS) formation, and fine texture of the materials that limited oxygen (02) diffusion into the biocover. Based on CH4 mass balance in the columns, the highest CH4 oxidation efficiency of 40% was observed in the column trial with the 1:4 mixing ratio of composts at a MC of 40% ww, with CH4 being oxidized throughout the entire height of the column. It can be concluded that this optimized design for YWLC and BSC mixture, removing a significant portion of the CH4 flowing through the landfill biocover, had the potential to be used in the real field conditions.
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