Bio-methanol produced from renewable resources, such as biogas, represents an interesting low carbon energy carrier due to its versatility. Few publications are available on the topic and ...techno-economic assessments focusing on the production of renewable methanol are needed to properly design such plants and understand their potential. To this purpose, a detailed techno-economic analysis of a 20 MWLHV biogas to methanol process via steam reforming is presented in this work. The process was designed to treat biogas produced via anaerobic digestion of municipal solid waste and be autonomous from a thermal viewpoint. The analysis included the comparison of three different process configurations, differing in the presence and position of the carbon dioxide separation unit. Sensitivity analyses were carried out on key process parameters, namely MeOH synthesis loop Recycle Ratio (RR, in the interval 3−7), methanol reactor pressure (pMeOH; 50–95bar) and Gas Hourly Space Velocity (GHSV,4000−8000; Nm3h·mCAT3). The best plant configuration was achieved when carbon dioxide separation was performed upstream of the reformer, which allowed to achieve higher carbon and fuel efficiencies. In the base case (RR=5, pMeOH=95bar, and GHSV=4000Nm3h·mCAT3), such configuration produced 2480kg/h of methanol, with a carbon and fuel efficiency equal to 51.4% and 72.2% respectively and a levelized cost of methanol of 378.0€/t. Reactor pressure considerably affected process profitability, whereas GHSV and RR had little impact on process economics. When methanol reactor pressure was decreased to 50bar, methanol production kept almost constant, but overall costs were remarkably lower. This led to a higher profitability, with a levelized cost of methanol of about 357.7€/t.
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•A biogas to methanol plant based on steam reforming is simulated in Aspen Plus.•Three plant configurations are compared based on the presence and position of CO2 removal system.•The best process configuration is identified in terms of energy performances and costs.•The levelized cost of methanol is estimated to be 357–381€/t•Economic optimum is found on methanol reactor pressure, space velocity, recycle ratio.
Reply Camilli, Massimiliano; Russo, Michele; Rinaldi, Riccardo ...
Journal of the American College of Cardiology,
03/2023, Letnik:
81, Številka:
12
Journal Article
Abstract
Context
Coronary collateral (CC) vessel development appears to be protective with regard to adverse cardiovascular events and survival in patients with coronary chronic total occlusion ...(CTO). The influence of type 2 diabetes mellitus (T2DM) on CC growth has been controversial. In particular, the role of diabetic microvascular complications (DMC) in determining coronary collateralization has not been elucidated.
Objective
To investigate whether patients with DMC presented differences in CC vessel presence and grading as compared with patients without DMC.
Methods
We conducted a single-center observational study, including consecutive T2DM patients, without previous cardiovascular history, undergoing a clinically indicated coronary angiography for chronic coronary syndrome (CCS) and angiographic evidence of at least one CTO. Patients were subdivided into 2 study groups according to the presence/absence of at least one DMC (neuropathy, nephropathy, or retinopathy). The presence and grading of angiographically visible CC development from the patent vessels to the occluded artery were assessed using the Rentrop classification.
Results
We enrolled 157 patients (mean age 68.6 ± 9.8 years; 120 76.4% men). Patients with DMC (75 47.8%) had a higher prevalence of CC (69 92.0% vs 62 75.6%, P = .006) and high-grade CC (55 73.3% vs 39 47.6%, P = .001) compared with those without, and we found a positive association between the number of DMC in each patient and the prevalence of high-grade CC.
Conclusion
Among T2DM patients with coronary CTO, the presence of DMC was associated with a high CC development.
Coronary vasomotor abnormalities are important causes of myocardial ischemia in patients with nonobstructive coronary artery disease (NOCAD). However, the role of air pollution in determining ...coronary vasomotor disorders has never been investigated.
We aimed to evaluate the association between long-term exposure to particulate matter 2.5 (PM2.5) and 10 (PM10), and coronary vasomotor disorders in NOCAD patients.
Patients with myocardial ischemia and NOCAD undergoing coronary angiography and intracoronary provocation test with acetylcholine were prospectively studied. Both patients with chronic myocardial ischemia and nonobstructive coronary arteries and myocardial infarction with nonobstructive coronary arteries (MINOCA) were enrolled. Based on each case's home address, exposure to PM2.5 and PM10 was assessed.
We included 287 patients (median age, 62.0 years IQR: 52.0-70.0 years, 149 51.9% males); there were 161 (56.1%) myocardial ischemia and nonobstructive coronary arteries and 126 (43.9%) MINOCA cases. One hundred seventy-six patients (61.3%) had positive provocation test. Exposure to PM2.5 and PM10 was higher in patients with a positive provocation test (P < 0.001). At multivariate logistic regression analysis, PM2.5 and PM10 were independent predictors of a positive provocation test (P = 0.001 and P = 0.029, respectively). Interestingly, among these patients, PM2.5 and PM10 were both independent predictors of MINOCA (P < 0.001 and P = 0.001, respectively) as clinical presentation, whereas PM2.5 was independently associated with the occurrence of epicardial spasm as opposed to microvascular spasm (P = 0.001).
Higher exposure to PM2.5 and PM10 in patients with myocardial ischemia and NOCAD is associated with coronary vasomotor abnormalities. In particular, PM2.5 is an independent risk factor for the occurrence of epicardial spasm and MINOCA as clinical presentation.
Previous studies reported a robust relation between chronic obstructive pulmonary disease (COPD) and coronary artery disease (CAD). Systemic inflammation has been proposed as possible pathogenetic ...mechanism linking these 2 entities, although data on atherosclerotic coronary features in COPD patients are lacking. We studied atherosclerotic coronary plaque features in COPD patients presenting with acute coronary syndrome (ACS) using optical coherence tomography (OCT). ACS patients who underwent intracoronary OCT imaging of the culprit vessel were enrolled. Coronary plaque characteristics and OCT-defined macrophage infiltration (MØI) were assessed by OCT. ACS patients were divided into 2 groups according to the presence of an established diagnosis of COPD, and plaque features at the culprit site and along the culprit vessel were compared between the groups. Of 146 ACS patients (mean age:66.1 ± 12.7 years, 109 men), 47 (32.2%) had COPD. Patients with COPD had significantly higher prevalence of MØI (78.7% vs 54.5%, p = 0.005) and thin cap fibroatheroma (TCFA) (48.9% vs 22.2%, p = 0.001) at the culprit site. In the multivariate logistic regression, COPD was independently associated with MØI (odds ratio OR 21.209, 95% confidence interval CI 1.679 to 267.910, p = 0.018) and TCFA at the culprit site (OR 5.345, 95% CI 1.386 to 20.616, p = 0.015). Similarly, COPD was independently associated with both MØI (OR 3.570, 95% CI 1.472 to 8.658, p = 0.005) and TCFA (OR 4.088, 95% CI 1.584 to 10.554, p = 0.004) along the culprit vessel. In conclusion, in ACS patients who underwent OCT imaging of the culprit vessel, COPD was an independent predictor of plaque inflammation and vulnerability. These results may suggest that a higher inflammatory milieu in COPD patients might enhance local coronary inflammation, promoting CAD development and plaque vulnerability.
Myocardial infarction with nonobstructive coronary arteries (MINOCA) represents about 6-8% of all patients with myocardial infarction (MI), and several pathophysiological mechanisms showed to be ...involved in this heterogeneous clinical condition. Of note, MINOCA proved to be associated with a significant risk of mortality, angina burden and socioeconomic costs.
Results from randomized clinical trials evaluating the clinical effectiveness of a comprehensive diagnostic algorithm, along with the acute and long-term management of patients with MINOCA, are pending.
In this review article, we aim at providing an overview of the clinical features, diagnostic work-up and the therapeutic management of patients presenting with MINOCA, highlighting the recent acquisition along with the remaining important knowledge gaps in this field.
Abstract
This article investigates changes in routine tasks and computer use in European jobs in the period 1995–2015, putting them in the context of the debates on the future of work and the impact ...of automation. Digital technologies not only affect employment shifts but also shape work organization. A shift-share analysis combining European Working Conditions Survey and European Labour Force Survey data assesses to what extent recent changes in tasks are the result of changes in the structure of employment (shifts in employment across jobs) or changes in the content of work itself (transformation in the task contents and methods within jobs). The results suggest contrasting trends between observed changes in tasks measures within jobs and compositional shifts in employment for routine tasks indexes. Employment structures are de-routinizing while work itself is becoming more routine. These results seem also related to the increased use of computers at work during the same period.
•The performances of a pillow-plate methanol reactor are assessed through CFD.•The CFD model is validated with a two dimensional heterogeneous model.•A sensitivity analysis is carried out on sheet ...distance for the pillow geometry.•A comparison of the performances of pillow-plate and tubular reactors is reported.
This work investigates the performances of a pillow-plate heat exchanger utilized as reactor for small-scale methanol synthesis. When downscaled, multi-tubular packed bed reactors are complicated to use since they undergo rapid losses in catalyst activity. A possible pathway to improve the unit performances is to diminish the tubes diameter and number. As this kind of reactors is governed by convective heat transfer, though, the use of long tubes is required to keep the mixture velocity high. This leads to the use of very long reactors, which cannot be easily realized with traditional designs. In order to tackle this issue, we propose the utilization of an innovative design, the pillow-plate reactor, increasing heat and mass transfer and the unit compactness. The study compares the performances of a packed-bed and a pillow-plate reactor through temperature profiles and methanol productivity at varying reactor lengths (1 – 6 m). It is proved that the pillow-plate unit, unlike the multi-tubular one, well manages scale reduction: when 1 m long reactors are employed, the outlet methanol fraction is close to equilibrium (5.8% vs. 4.9% for packed beds) and the hot-spots are well controlled (537 K vs. 557 K for tubular reactors). Moreover, it is also shown that the distance of metal layers in the pillow arrangement remarkably influences heat exchange, which is very effective for close layers, with a hot-spot of 518 K with a 3 mm gap, and much worse for the 12 mm design (552 K).
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