High-resolution neutronics model for ^(238)Pu production in high-flux reactors

We proposed and compared three methods(filter burnup,single energy burnup,and burnup extremum analysis)to build a high-resolution neutronics model for 238Pu production in high-flux reactors.The filter burnup and single energy burnup methods have no theoretical approximation and can achieve a spectrum resolution of up to~1 eV,thereby constructing the importance curve and yield curve of the full energy range.The burnup extreme analysis method combines the importance and yield curves to consider the influence of irradiation time on production efficiency,thereby constructing extreme curves.The three curves,which quantify the transmutation rate of the nuclei in each energy region,are of physical significance because they have similar distributions.A high-resolution neutronics model for ^(238)Pu production was established based on these three curves,and its universality and feasibility were proven.The neutronics model can guide the neutron spectrum optimization and improve the yield of ^(238)Pu by up to 18.81%.The neutronics model revealed the law of nuclei transmutation in all energy regions with high spectrum resolution,thus providing theoretical support for high-flux reactor design and irradiation production of ^(238)Pu.

High-flux electron beams from laser wakefield accelerators driven by petawatt lasers

Laser wakefield accelerators （LWFAs） are considered to be one of the most compeuuve next- generation accelerator candidates. In this paper, we will study the potential high-flux electron beam production of an LWFA driven by petawatt-level laser pulses. In our three-dimensional particle-in-cell simulations, an optimal set of parameters gives -40 nC of charge with 2 PW laser power, thus -400 kA of instantaneous current if we assume the electron beam duration is 100 fs. This high flux and its secondary radiation are widely applicable in nuclear and QED physics, industrial imaging, medical and biological studies.

Mapping the Wall-Region Dynamics of High-Flux Gas-Solid Riser Using Scaling Regions from the Solid Concentration Time Series

An experimental study of the gas-solid flow dynamics in the high-flux CFB riser was accomplished by analysing the scaling regions from solid concentration signals collected from a 76 mm internal diameters and 10 m high riser of a circulating fluidized bed (CFB) system. The riser was operated at 4.0 to 10.0 m/s gas velocity and 50 to 550 kg/m2s solids flux. Spent fluid catalytic cracking (FCC) catalyst particles of 67 μm mean diameter and 1500 kg/m3 density together with 70% to 80% humid air was used. Solid concentration data were analysed using codes prepared in FORTRAN 2008 to get correlation integrals at different embedding dimensions and operating conditions and plot their profiles. Scaling regions were identified by visual inspection method and their location on planes determined. Scaling regions were analysed based on operating conditions and riser spatial locations. It was found that scaling regions occupy different locations on the plane depending on the number of embedding dimensions and operating conditions. As the number of embedding dimensions increases the spacing between scaling regions decreases until it saturates towards higher embedding dimensions. Slopes of scaling regions increases with embedding dimensions until saturation where they become constant. Slopes of scaling regions towards the wall decrease while the number of scaling regions for a particular profile increases. The span of the scaling region is wider at the initial values of hyperspherical radius than its final values. The scaling regions in some flow development sections show multifractal behaviour for each embedding dimension which manifests into visible basin which is defined in this study as multifractal basin. Further, the end points of the scaling region for each correlation integral profile differ from each other as the embedding dimension changes. This study suggests that identification of scaling region by visual inspection method is useful in understanding the gas-solid flow dynamics in the High-Flux CFB riser system. Further studies are recommended on risers of different diameters and heights operated at low and high solid fluxes and different gas velocities for comparison or usage of time series of different signal types like pressure fluctuations.

Mapping Correlation Dimension along the Wall Region of a High-Flux Gas-Solid Riser Using Embedded Solid Concentration Time Series

Analysis of the entrance and wall dynamics of a high-flux gas-solid riser was conducted using embedded solid concentration time series collected from a 76 mm internal diameter and 10 m high riser of a circulating fluidized bed (CFB) system. The riser was operated at 4.0 to 10.0 m/s air velocity and 50 to 550 kg/m2s solids flux of spent fluid catalytic cracking (FCC) catalyst particles with 67 μm mean diameter and density of 1500 kg/m3. Data were analyzed using prepared FORTRAN 2008 code to get correlation integral followed by determination of correlation dimensions with respect to the hyperspherical radius and their profiles, plots of which were studied. It was found that correlation dimension profiles at the centre have single peak with higher values than the wall region profiles. Towards the wall, these profiles have double or multiple peaks showing bifractal or multifractal flow behaviors. As the velocity increases the wall region profiles become random and irregular. Further it was found that, as the height increases the correlation dimension profiles shift towards higher hyperspherical radius at the centre and towards lower hyperspherical radius in the wall region at r/R = 0.81. The established method of mapping correlation dimension profiles in this study forms a suitable tool for analysis of high-flux riser dynamics compared to other analyses approaches. However, further analysis is recommended to other gas-solid CFB riser of different dimensions operated at high-flux conditions using the established method.

Analysis of Flow Dynamics in the High-Flux Gas-Solid Riser Using Trajectory Distances across Attractors Reconstructed from Solid Concentration Signals

The study of the entrance and wall dynamics of a high-flux gas-solid riser was conducted using trajectory distances of the reconstructed attractors from solid concentration signals collected from a 76 mm internal diameters and 10 m high riser of a circulating fluidized bed (CFB) system. The riser was operated at 4.0 to 10.0 m/s gas velocity and 50 to 550 kg/m2s solids flux. Spent fluid catalytic cracking (FCC) catalyst particles with 67 μm mean diameter and density of 1500 kg/m3 together with 70% to 80% humid air was used. Solid concentration data were analyzed using codes prepared in FORTRAN 2008 to get trajectories of the reconstructed attractors and their distances apart. Trajectory distances were found to increase from the centre towards the wall indicating the expansion of the attractor. The probability density function (PDF) of the trajectory distances changes from single peak at the centre to multiple peaked profiles in the wall region. Multiple peaked profiles indicate multifractal flow behaviours. Cumulative distribution functions (CDF) of the trajectory distances changes from single S-shaped at the centre to multiple S-shaped profiles in some locations of the wall region indicating multifractal flow behaviours. The PDF distribution of these distances at the entrance section and in the wall region forms different types of statistical distributions showing differences in gas-solid flow structures in various spatial locations of the wall region and the entrance sections. Most of the distributions at the centre fall under the Gumbel max distribution for all flow development sections of the riser, especially at air velocities of 5.5 m/s and 8 m/s showing uniform flow structures. Further, it was found that increase of the number of the phase space reconstruction embedding dimension increases the trajectory distances between the state vectors leading to the expansion of the attractor.

Effects of High-Flux Hemodialysis on Inflammatory Factors and Nutritional Status in Patients with Severe Renal Failure

Objective:To investigate the effects of high-flux hemodialysis on inflammatory factors and nutritional status in patients with severe renal failure.Methods:A total of 72 patients with severe renal failure who underwent dialysis treatment in the hospital from January 2017 to March 2019 were selected as the research subjects,and they were randomly divided into 2 groups with 36 patients each.The control group underwent low-flux hemodialysis,and the observation group underwent high-flux hemodialysis.The levels of inflammatory factors and nutritional status were compared between the two groups after treatment.Results:The levels of various inflammatory factors in the observation group were lower than those in the control group and the nutritional indexes were higher than those in the control group after 4 weeks of treatment(P<0.05).Conclusion:High-throughput hemodialysis in patients with severe renal failure can significantly reduce the levels of inflammatory factors and improve nutritional status.

Progress of high-flux hemodialysis in clinical application, complications and treatment

Hemodialysis is the main method of clinical renal replacement therapy, and its effectiveness and safety have been widely confirmed. High-flux hemodialysis, as a constantly updating new mode in the field of blood purification, has effectively improved the efficiency of hemodialysis and reduced the incidence of hemodialysis complications. High-flux hemodialysis has been widely used in clinical practice, and mainly plays its role through adsorption, convection and dispersion. High-flux hemodialysis has some advantages not possessed by conventional hemodialysis, including protecting injured renal function, reducing the incidence of cardiovascular complications in hemodialysis patients, improving the patients' nutritional status, reducing the occurrence of renal osteopathy and delaying the occurrence time of dialysis-associated amyloidosis. However, high-flux hemodialysis also has some limitations, such as the elimination of drugs and nutrients, and the backfiltration caused by increased pressure on the dialysis membrane and dialysate side. In this review, the related progress of high-flux hemodialysis in clinical application, mechanism, complications and treatment are discussed in order to provide a reference for its more rational clinical use.

Effect of high-flux and low-flux hemodialysis on the side metabolites and cytokines in patients with uremia

Objective:To study the effect of high-flux and low-flux hemodialysis on the side metabolites and cytokines in patients with uremia.Methods: A total of 50 patients with uremia who accepted high-flux hemodialysis and 140 patients with uremia who accepted low-flux hemodialysis in our hospital between March 2015 and March 2016 were selected and included in high-flux group and low-flux group respectively. Before and after dialysis, serum was collected respectively to determine the levels of side metabolites, calcium-phosphorus metabolism indexes and cytokines.Results: 3 months after dialysis, serum Ca levels of two groups of patients were not significantly different from those before dialysis while BUN, Scr,β2-MG, sTfR, P, PTH and AKP levels were significantly lower than those before dialysis;3 months after dialysis, serum BUN, Scr and Ca levels of high-flux group were not significantly different from those of low-flux group whileβ2-MG, sTfR, P, PTH, AKP, TNF-α, IL-1β, IL-6, IL-8 and IL-10 levels were significantly lower than those of low-flux group.Conclusion:Compared with low-flux hemodialysis, high-flux hemodialysis treatment of uremia can more effectively remove middle molecular and macromolecular toxins, correct calcium-phosphorus metabolism disorder and relieve micro-inflammatory state.

Effects of high-flux hemodialysis on plasma adrenomedullin and sustained hypotension in elderly hemodialysis patients

Background Sustained hypotension during hemodialysis （HD） is an important clinical issue. Plasma adrenomedullin （AM） is increased in HD patients with sustained hypotension, but little is known about whether removing AM can improve hypotension. The objective of this study was to investigate the beneficial effects of hemodialysis using a high-flux dialyzer on removal of increased plasma AM levels and improving low blood pressure in elderly HD patients with sustained hypotension.Methods Forty-eight elderly patients （age 65 or older） who had undergone maintenance HD for more than one year were recruited and studied. We evaluated plasma levels of AM in sustained hypotension （SH; n=28） and normotensive （NT; n=20） patients. The patients with hypotension were further divided into two subgroups and treated with eitherhigh-flux dialyzer or low-flux dialyzer for 3 months. Plasma adrenomedullin levels and blood pressure were analyzed at days 0 and 181.Results Plasma levels of AM were significantly higher in SH than in NT patients （（24.92±3.7） ng/L vs. （15.52±6.01） ng/L,P〈0.05）, and were inversely correlated with mean arterial blood pressure （MAP） at pre-HD. After 3 months, the level of plasma AM in high-flux group was decreased （（24.58±4.36） ng/L vs. （16.18±5.08） ng/L, P 〈0.05）, but MAP was increased （（67.37±4.31） mmHg vs. （74.79±3.59） mmHg, P〈0.05）. There was no obvious change in low-flux group.Conclusions Plasma AM levels were significantly elevated in elderly HD patients with SH. High-flux dialyzer therapy can decrease plasma AM level and improve hypotension.

Particle clustering(mesoscale structure)of high-flux gas-solid circulating fluidized bed

Particle clustering is an important dynamic phenomenon in circulating-fluidized-bed(CFBs)systems,and has been suggested as a key contributing factor to the non-uniform hydrodynamics of CFBs.Studies show that particle clusters can be affected by solids flux,in terms of frequency,duration,and solids holdup.To understand the characteristics of particle clusters under high-solids-flux conditions,experimental and modeling studies in high-solids-flux gas-solids CFBs were reviewed and summarized.Optical and electrical measurements and imaging methods were used to monitor the particle-clustering phenomenon in CFBs.Particles were found to cluster in high-flux CFBs,and were characterized by a denser cluster-solids holdup and a shorter time fraction,which was different from the behavior in low-flux CFBs.Particle properties affected particle clustering in high-flux CFBs significantly.In modeling work,Eulerian-Eulerian and Eulerian-Lagrangian methods were used to study the particle-cluster characteristics.Good results can be obtained by using the Eulerian-Eulerian method to simulate the CFB system,especially the high-flux CFBs,and by considering the effects of particle clusters.The Eulerian-Lagrangian method is used to obtain detailed cluster characteristics.Because of limits in computing power,no obvious results exist to model particle clusters under high-solids-flux conditions.Because high-solids-flux conditions are used extensively in industrial applications,further experimental and numerical investigations on the clustering behavior in HF/DCFBs are required.

Geomorphological-geological-geophysical signatures of high-flux fluid flows in the eastern Pearl River Mouth Basin and effects on gas hydrate accumulation

Marine hydrate reservoirs can be divided into focused high-flux and distributed low-flux gas hydrate systems according to free gas migration control mechanisms. In focused high-flux hydrate reservoirs, fluids easily break through the pressure of overlying sediments and reach the shallows, creating a series of geomorphological-geological-geophysical anomalies at and near the seafloor. Based on detailed interpretation of pre-drilling data in the eastern Pearl River Mouth Basin(PRMB),many anomalies related to the high-flux fluid flow are found, including seafloor mounds with intrusive characteristics, bright spot reflections above the bottom-stimulating reflector(BSR), phase reversals in the superficial layer, and an efficient fluid migration and accumulation system composed of fractures and uplifts. The second hydrate drilling expedition was carried out in the eastern PRMB in 2013 to study these anomalies. The acquired data show that high-flux fluid flow occurred in these sites. Gas hydrate pingoes, bright spot reflection above the BSR, and an efficient fluid migration and accumulation system can be used as identification signatures for high-flux fluid migration. The modes of high flux fluid flow are different in deep and shallow sediments during upward migration of fluid. Gas dissolved within migrating water dominates deep fluid migration and upward migration of a separate gas phase dominates the shallow process. This difference in migration models leads to formation of upper and lower concentrated hydrate reservoirs in the drilling area. The discovery of signatures of high-flux fluid flow and their migration modes will help with site selection and reduce risk in gas hydrate drilling.

ANALYSIS OF THE CHAOTIC DYNAMICS OF A HIGH-FLUX CFB RISER USING SOLIDS CONCENTRATION MEASUREMENTS

A high-flux circulating fluidized bed （CFB） riser （0.076-m I.D. and 10-m high） was operated in a wide range of operating conditions to study its chaotic dynamics, using FCC catalyst particles （dp= 67μm, ρp = 1500 kg·m^-3）. Local solids concentration fluctuations measured using a reflective-type fiber optic probe were processed to determine chaotic invariants （Kolmogorov entropy and correlation dimension）, Radial and axial profiles of the chaotic invariants at different operating conditions show that the core region exhibits higher values of the chaotic invariants than the wall region. Both invariants vary strongly with local mean solids concentration. The transition section of the riser exhibits more complex dynamics while the bottom and top sections exhibit a more uniform macroscopic and less-complex microscopic flow structure. Increasing gas velocity leads to more complex and less predictable solids concentration fluctuations, while increasing solids flux generally lowers complexity and increases predictability. Very high solids flux, however, was observed to increase the entropy.

高通量透析联合血液灌流对老年维持性血液透析患者残余肾功能及免疫功能的影响

目的 探讨高通量透析联合血液灌流对老年维持性血液透析(MHD)患者残余肾功能(RRF)及免疫功能的影响。方法 选择2020年12月至2022年12月周口市中心医院收治的96例老年MHD患者,随机分为对照组和研究组各48例。对照组患者接受高通量透析治疗,研究组患者接受高通量透析联合血液灌流治疗,对比两组血清钙、磷及甲状旁腺激素(iPTH)水平、RRF、免疫功能[免疫球蛋白(IgG、IgM)、CD4^(+)、CD8^(+)、CD4^(+)/CD8^(+)]及不良反应。结果 透析3个月后,两组钙水平升高,磷、iPTH水平降低(P<0.05);且研究组钙水平高于对照组,磷、iPTH水平低于对照组(P<0.05)。透析3个月后,两组RRF水平下降(P<0.05);研究组RRF水平高于对照组(P<0.05)。透析3个月后,两组CD4^(+)、CD4^(+)/CD8^(+)、IgG、IgM水平升高,CD8^(+)水平降低(P<0.05);且研究组CD4^(+)、CD4^(+)/CD8^(+)、IgG、IgM水平高于对照组,CD8^(+)水平低于对照组(P<0.05)。两组不良反应发生率对比差异无统计学意义(P>0.05)。结论 高通量透析联合血液灌流可有效调节老年MHD患者钙、磷及iPTH水平,促进免疫功能恢复,同时维护RRF,且不增加不良反应,是一种安全可靠的治疗方案。

高通量血液透析联合血液透析滤过序贯治疗慢性肾衰竭的临床效果及对钙磷代谢、预后的影响

目的分析高通量血液透析(HFHD)联合血液透析滤过(HDF)序贯治疗慢性肾衰竭(CRF)的临床效果。方法选取2020年1月至12月我院接收的90例CRF患者为研究对象,随机将其分为常规组(45例,常规HFHD治疗)和联合组(45例,HFHD联合HDF序贯治疗)。比较两组的治疗效果。结果联合组的治疗总有效率高于常规组(P<0.05)。治疗后,联合组的血尿素氮(BUN)、血肌酐(Scr)、甲状旁腺素(PTH)及β2-微球蛋白(β2-MG)水平低于常规组,内生肌酐清除率(Ccr)显著高于常规组(P<0.05)。治疗后,联合组的钙(Ca)水平高于常规组,磷(P)、成纤维细胞生长因子-23(FGF-23)、镁(Mg)、降钙素(CT)及碱性磷酸酶(ALP)水平低于常规组,差异具有统计学意义(P<0.05)。治疗后,联合组的肿瘤坏死因子-α(TNF-α)、C反应蛋白(CRP)及白细胞介素-8(IL-8)水平低于常规组,白细胞介素-10(IL-10)水平高于常规组,差异具有统计学意义(P<0.05)。联合组的不良反应总发生率低于常规组,差异具有统计学意义(P<0.05)。结论HFHD联合HDF序贯治疗CRF可取得理想的效果。

电动汽车用新型模块化聚磁转子永磁电机设计及其对比分析

将轮辐型内置式转子和Halbach永磁阵列结合,并取消转子铁心加强筋,减小漏磁达到高聚磁同时兼顾凸极比,实现高转矩/功率密度和宽调速范围。在保证永磁体用量相同的情况下,建立新型高凸极比聚磁转子和V型转子两种电机模型,针对两者的分段转子拓扑,开展电磁性能对比分析,包括气隙磁密、凸极比、功率以及弱磁扩速能力等。同时,考虑到无转子铁心加强筋会导致转子分段存在结构强度问题,仿真验证新型高凸极比聚磁转子结构在最高转速6000 r/min时给予碳纤维护套保护下转子结构强度的可靠性;分析温度限制下新型高凸极比转子电机的功率输出。另外,对比两种不同电机结构的振动噪声情况。最后,研制一台16极/72槽新型高凸极比转子永磁电机样机,实验验证有限元分析结果的准确性。进一步说明了新型高凸极比转子永磁电机在转矩/功率密度和宽调速运行等方面的性能优势。

卫星有源相控阵高热流微尺度器件热设计与验证

为解决卫星有源相控阵高热流微尺度器件散热和热试验验证难题,首先,提出T/R模块低温共烧陶瓷热设计优化方案,选择热通孔面积比为11.4%,并建立尺度比为800∶1的跨尺度热模型;其次,进行地面常压热平衡试验,利用红外热像仪测量器件温度;再基于热参数敏感性分析方法评估自然对流、热辐射和热传导有关参数对器件温度的影响,结果表明:对于特征长度为600μm的典型器件,接触热导对散热影响最大,而自然对流和热辐射影响均低于2%;基于常压热平衡试验数据修正热模型后的仿真与试验数据吻合良好,最大温度偏差1.7℃;高热流微尺度器件接触热导为16200 W/(m^(2)·K),预示真空下器件的最高温度为73.2℃,满足工程要求。研究结果可为卫星高热流微尺度器件热设计和验证提供参考。

低钠透析液高通量透析对伴发高血压的维持性透析患者血压恢复及外周血AngⅡ、肾素水平的影响

目的观察低钠透析液高通量透析对伴发高血压的维持性透析患者血压恢复及外周血血管紧张素(Ang)Ⅱ、肾素水平的影响。方法前瞻性选取2022年2月至2024年2月在秦皇岛市第一医院进行维持性透析的100例伴发高血压患者为对象,按照信封法分为正常组(n=50)和低钠组(n=50)。正常组给予140 mmol/L正常钠透析液进行高通量透析,低钠组给予135 mmol/L低钠透析液进行高通量透析。检测两组治疗前、治疗12周后的24 h动态血压(24 h收缩压和舒张压、日间平均收缩压和舒张压、夜间平均收缩压和舒张压、血压负荷)、肾素-血管紧张素-醛固酮系统(RAAS)相关因子(AngⅠ、AngⅡ、肾素、醛固酮)、内皮素-1、甲状旁腺激素(PTH)、同型半胱氨酸(Hcy)、一氧化氮(NO)水平,并记录两组不良反应发生情况。结果治疗12周后,两组24 h收缩压和舒张压、日间收缩压和舒张压、夜间收缩压和舒张压、血压负荷均较治疗前降低,且低钠组的24 h收缩压和舒张压、日间收缩压和舒张压、夜间收缩压和舒张压、血压负荷分别为(131.12±6.58)mmHg、(74.47±3.95)mmHg、(140.25±6.95)mmHg、(81.25±4.06)mmHg、(132.52±6.71)mmHg、(77.11±4.69)mmHg、(25.65±5.94)%,均低于正常组[(138.25±7.15)mmHg、(79.14±4.23)mmHg、(151.25±8.22)mmHg、(89.96±4.44)mmHg、(139.96±6.77)mmHg、(87.41±5.07)mmHg、(32.32±6.15)%],差异均有统计学意义(P<0.05)。治疗12周后,两组AngⅠ、AngⅡ、肾素、醛固酮水平均较治疗前降低,且低钠组的AngⅠ、AngⅡ、肾素、醛固酮水平分别为(2.74±0.67)ng/mL、(97.33±18.14)pg/mL、(2.04±0.67)ng/(mL·h)、(137.14±26.95)pg/mL,均低于正常组[(3.23±0.89)ng/mL、(126.21±20.44)pg/mL、(2.56±0.78)ng/(mL·h)、(189.54±32.25)pg/mL],差异均有统计学意义(P<0.05)。治疗12周后,两组PTH、Hcy、内皮素-1水平均较治疗前降低,NO水平均较治疗前升高,且低钠组的PTH、Hcy、内皮素-1水平分别为(134.75±18.62)pg/mL、(14.45±2.67)μmol/L、(64.03±5.11)μmol/L,均低于正常组[(167.54±20.44)pg/mL、(19.04±3.54)μmol/L、(71.14±5.82)μmol/L],NO水平为(16.88±2.89)μg/mL,高于正常组[(13.54±2.27)μg/mL],差异均有统计学意义(P<0.05)。两组总不良反应发生率比较,差异无统计学意义(P>0.05)。结论低钠透析液高通量透析可降低伴发高血压的维持性透析患者血压水平,可能与调节肾素-血管紧张素-醛固酮系统与血管内皮功能有关。

超高参数火箭煤油在小通道圆管内的流动换热特性

火箭煤油再生冷却过程具有高压、高温、高热流密度和高质量流速等特点。在超高参数条件下,采用低电压大电流电加热方法模拟火箭发动机推力室壁面热环境,在高温合金钢∅2 mm×0.5 mm圆管内研究了火箭煤油的流动换热特性。参数范围为压力25~65 MPa,质量流速8500~51000 kg/(m^(2)·s),流体温度常温为~500℃,热流密度最高为35 MW/m^(2)。研究表明:在所测试条件下,火箭煤油在小通道圆管内处于单相液态强制对流换热机制;换热性能主要受到流体温度和质量流速的影响;流体温度增加,换热系数增加;质量流速增加,换热系数增加;压力在25~65 MPa范围内对换热性能无显著影响;热流密度增加,内壁温显著增加,但热流密度变化对换热系数无显著影响;受入口强化换热效应的影响,换热系数增加,热流密度越高,入口效应越明显。超高参数尤其是超高压力条件下的火箭煤油换热特性,为火箭煤油再生冷却技术应用提供参考。

半直驱MW级轴向磁通永磁风力发电机电磁设计与分析

在大功率直驱式风力发电机设计中,针对轴向磁通永磁发电机径向尺寸大、后期维护成本高的问题,文章将轴向磁通永磁发电机设计为大功率半直驱式风力发电机。以2 MW半直驱轴向磁通永磁发电机为研究对象,研究其参数设计原则和方法。通过探究不同极对数对发电机输出性能的影响,确定满足设计目标的发电机优选方案。采用3D有限元分析法对发电机空载和额定负载工况下的气隙磁密、电压、电流波形以及输出功率、损耗和效率进行分析,验证发电机电磁设计的正确性,发电机效率可以达到97.79%,具有损耗小、效率高的优点。通过与现有发电机进行对比,文章所提出的半直驱MW级轴向磁通永磁发电机径向尺寸显著减小,且在轴向尺寸和齿槽转矩方面比现有径向磁通结构的大功率半直驱永磁发电机表现更优。

脱庚烷塔分离效果差的原因分析及改进措施

异构化装置脱庚烷塔主要任务是分离C_(8)芳烃中的C_(6)~C_(7)馏分,为二甲苯装置提供原料。脱庚烷塔分离效果差,造成C_(8)芳烃损失,其主要原因一是外购混合二甲苯带有溶解氧,引起烯烃在进料换热器壳层升温后发生聚合,生成黏稠产物,导致脱庚烷塔进料温度低;二是高通量管换热器E-707基管表面多孔涂层覆有垢层,导致换热效果下降,换热能力不足。经过流程优化和更换换热器后,脱庚烷塔分离效果提升明显,塔顶C_(8)芳烃质量分数由10.00%降至1.34%,塔底苯质量分数低于0.01%,甲苯质量分数由1.16%降至0.38%。