Solution of Coal Char-steam Pressurized Kinetic Parameters Based on Atmospheric Thermo Gravimetric Analyzer

根据文献中气化速率对总压不敏感、对反应气体分压敏感的实验结论，探索利用常压热重实验得到加压动力学参数的便捷方法。采用NETZSCH STA449F3同步热分析仪进行4种煤焦与水蒸气反应的常压热重实验（水蒸气分压pH2O为0.016~0.053 MPa），通过实验数据处理，获得反应速率与温度、水蒸气分压的关系式，分别以 n 级速率方程和Langmuir-Hinshelwood （LH）速率方程表示，并对上述关系式在水蒸气分压为0.057~0.063 MPa 的工况下进行了实验验证。随着水蒸气分压增大，计算结果与实验数据的相对误差逐渐减小。LH速率方程比n级速率方程更适合描述水蒸气分压的作用。水蒸气分压对反应速率的影响程度随水蒸气分压升高而减小。温度对煤焦-水蒸气反应速率的影响程度大于水蒸气分压对反应速率的影响。温度范围较窄时，煤种本身引起的煤焦反应活性变化幅度会超过温度对煤焦反应活性的影响。在不同的温度和水蒸气分压下，煤种的化学反应活性强弱次序会发生变化，某一特定工况下的次序不能未加实验而随意扩展到其他工况。

Modeling the kinetics of methane conversion in steam reforming process of coke-oven gas based on experimental data

Steam-reforming is an effective approach for upgrading methane and hydrocarbon of coke-oven gas into CO and HE, but the kinetic behavior needs more study. We investigated the conversion of methane in coke-oven gas by steam reforming process in an electric tubular flow at 14 kPa with temperature varying from .500 ℃ to 9.50 ℃, and developed a kenetic model for, ignoring the effects of adsorption and diffusion. The optimal dynamic conditions for methane conversion 14 kPa are as follows： the ratio of the amount of water to the amount of methane is from 1.1 to 1.3; the reaction temperature is from 1 223 K to 1 273 K. The methane conversion rate is larger than 95% when the ratio of the amount of water to the amount of methane is 1.2 at a temperature above 1 223 K with the residence time up to 0.75 s.

Prediction of Boiler Drum Pressure and Steam Flow Rate Using Artificial Neural Network

Numerical simulation of complex systems and components by computers is a fundamental phase of any modern engineering activity. The traditional methods of simulation typically entail long, iterative processes which lead to large simulation times, often exceeding transient real time. Artificial neural networks （ANNs） may be advantageous in this context, the main advantage being the speed of computation, the capability of generalizing from the few examples, robustness to noisy and partially incomplete data and the capability of performing empirical input-output mapping without complete knowledge of underlying physics. In this paper, the simulation of steam generator is considered as an example to show the potentialities of this tool. The data required for training and testing the ANN is taken from the steam generator at Abott Power Plant, Champaign （USA）. The total number of samples is 9600 which are taken at a sampling time of three seconds. The performance of boiler （drum pressure, steam flow rate） has been verified and tested using ANN, under the changes in fuel flow rate, air flow rate and load disturbance. Using ANN, input-output mapping is done and it is observed that ANN allows a good reproduction of non-linear behaviors of inputs and outputs.

Performance Analysis of Induced Draft Fan Driven by Steam Turbine for 1000 MW Power Units

Boiler fan is the main power consumption device in thermal power units and the induced draft fan accounted for the largest proportion. Reducing the energy consumption rate of induced draft fan is the main path to reduce the power consumption rate of thermal power units. The induce fan driven by small turbine is greatly effective for reducing the power consumption rate and the supply coal consumption rate in large thermal power plant. Take 1000 MW power units for example, the selection of steam source for steam turbine were discussed and economic performance of the unit under different steam source was compared in this paper. The result shows that compared with the motor driven method, there is about 1.6 g/kWh decrease in supply coal consumption rate driven by the fourth stage extraction steam;whereas there is about 2.5 g/kWh decrease in supply coal consumption rate driven by the fifth stage extraction steam.

Kinetic model on coke oven gas with steam reforming

The effects of factors such as the molar ratio of H2O to CH4 (n(H2O)/n(CH4)), methane conversion temperature and time on methane conversion rate were investigated to build kinetic model for reforming of coke-oven gas with steam. The results of experiments show that the optimal conditions for methane conversion are that the molar ratio of H2O to CH4 varies from 1.1 to 1.3 and the conversion temperature varies from 1 223 to 1 273 K. The methane conversion rate is more than 95% when the molar ratio of H2O to CH4 is 1.2, the conversion temperature is above 1 223 K and the conversion time is longer than 0.75 s. Kinetic model of methane conversion was proposed. All results demonstrate that the calculated values by the kinetic model accord with the experimental data well, and the error is less than 1.5%.

Feasibility Study of Solar Energy Steam Generator for Rural Electrification

In Middle East region, where there are plentiful amounts of solar radiation and great desert areas, solar energy can play a potential role in replacing conventional fuel-operated electricity generation methods with a cost-effective, sustainable solution. This paper presents a feasibility study of a low-cost solar energy steam generator for rural areas electrification. The proposed system is based on the use of trough concentrator which converts solar radiation into thermal energy in its focal line (where a receiver pipe is installed with a fluid flowing in its interior). The aim of the paper is to predict the feasibility and potential for steam generation using a stand-alone solar concentrator with a small dimension for domestic and small-scale electricity generation. The study presented here is based on modelling of the system to determine the points at which the system is expected to produce sufficient steam energy at the tube outlet to drive a steam engine for producing electricity. Results are presented in graphical forms to show the operating points and the effect of changing selected input parameters on the behavior of the system in order to set some limits (boundaries) for such parameters. Results show that among the three input design parameters selected, the tube diameter is the most dominant parameter that influences steam energy, then the tube length and finally the flow rate of the water passing through the tube. The results of this paper can provide a useful guideline for future simulation and/or physical implementation of the system.

Analysis of Energy Consumption and Energy Conservation Measures for RFCCU at Shengli Petrochemical Company

This article introduces a string of energy conservation measures adopted over the past sev- eral years by the RFCC unit at Shengli Petrochemical Complex, including the optimization of feedstock properties, the adoption of high-efficiency atomizing nozzles, the revamp of CO boiler, the atomization by means of dry gas, the post-burning of flue gas as well as the application of frequency converting machines and pumps, resulting in ideal effects. The energy consumption of the RFCC unit was gradually decreased to 2984.25 MJ/t from the original level of 3716.99 MJ/t. After comparing basic energy con- sumption values with actual consumption values, the authors have set forward measures for further energy conservation, such as the recovery of low-temperature excess heat contained in oil/gas streams exiting from the fractionation tower top, addition of the fourth cyclone, delivery of hot oil slurry, and heat tracing with hot water.

Optimization of operating conditions in the steam turbine blade cascade using the black-box method

Water droplets cause corrosion and erosion,condensation loss,and thermal efficiency reduction in low-pressure steam turbines.In this study,multi-objective optimization was carried out using the black-box method through the automatic linking of a genetic algorithm(GA)and a computational fluid dynamics(CFD)code to find the optimal values of two design variables(inlet stagnation temperature and cascade pressure ratio)to reduce wetness in the last stages of turbines.The wet steam flow numerical model was used to calculate the optimization parameters,including wetness fraction rate,mean droplet radius,erosion rate,condensation loss rate,kinetic energy rate,and mass flow rate.Examining the validation results showed a good agreement between the experimental data and the numerical outcomes.According to the optimization results,the inlet stagnation temperature and the cascade pressure ratio were proposed to be 388.67(K)and 0.55(-),respectively.In particular,the suggested optimaltemperature and pressure ratio improved the liquid mass fraction and mean droplet radius by about 32%and 29%,respectively.Also,in the identified optimal operating state,the ratios of erosion,condensation loss,and kinetic energy fell by 76%,32.7%,and 15.85%,respectively,while the mass flow rate ratio rose by 0.68%.

油渣半焦与水蒸气及CO_(2)共气化特性研究

研究煤直接液化残渣的气化特性可促进煤直接液化残渣的高效利用,进而提高煤液化工艺的经济性和环境效益。以神华煤直接液化残渣制得的油渣半焦及脱灰油渣半焦为实验样品,利用常压热重,研究气化温度950、1000、1050℃和气化剂浓度30%、60%、90%条件下油渣半焦与水蒸气及CO_(2)单独气化反应性的差异,以及在气化温度1000℃和气化剂浓度60%条件下脱灰油渣半焦与水蒸气及CO_(2)单独气化反应性的差异、油渣半焦与水蒸气及CO_(2)共气化的协同效应。研究发现:油渣半焦与CO_(2)的气化反应性除个别条件外,均高于与水蒸气的气化反应性;脱灰油渣半焦与CO_(2)的气化反应性明显低于与水蒸气的气化反应性。油渣半焦与不同浓度的CO_(2)和水蒸气共气化反应的碳转化率实验值均略低于计算值,油渣半焦与不同浓度的CO_(2)和水蒸气共气化产生了负的协同效应。油渣半焦与水蒸气及CO_(2)气化,同一气化剂配比下反应性指数R′均随气化温度的升高而增大,同一气化温度下反应性指数(R′)均随气化剂配比的升高而增大。相同条件下,油渣半焦在CO_(2)气氛下反应性指数高于水蒸气气氛;脱灰油渣半焦CO_(2)气氛下的反应性指数(R′)显著低于水蒸气气氛的反应性指数。油渣半焦的反应性显著高于脱灰油渣半焦,在CO_(2)气氛下该种情况更显著。

两种方法清洗消毒达芬奇机器人手术臂的效果比较

目的探讨达芬奇机器人手术臂有效的清洗消毒方法。方法回顾性分析2022年1月至2023年4月江西省人民医院手术室使用后的达芬奇机器人手术臂200件达芬奇机器人手术臂作为研究对象,按照不同的操作流程将其分为观察组(100件)与对照组(100件)。观察组采用流动水冲洗+腹腔镜酶剂浸泡+超声波清洗机超声+蒸汽清洗机清洗手术臂操作端+高压水枪纯水漂洗+全自动清洗机清洗消毒。对照组清洗消毒流程为流动水冲洗+腹腔镜酶剂浸泡+超声波清洗机超声+刷洗手术臂操作端+高压水枪纯水漂洗+全自动清洗机清洗消毒。采用目测检查法(四倍带光源放大镜)、腺苷三磷酸(ATP)生物荧光快速检测法进行检测,计算清洗质量不合格的返洗率,比较两组的清洗消毒操作平均耗时。结果观察组的目测检查法返洗率低于对照组,观察组的ATP生物荧光检测返洗率低于对照组,差异有统计学意义(P<0.05)。观察组清洗消毒平均耗时短于对照组,差异有统计学意义(P<0.05)。结论蒸汽清洗机清洗消毒达芬奇机器人手术臂效果比手工刷洗清洗消毒效果更为理想,可节约大量清洗消毒时间,有效节约稀有医疗资源。

某660MW机组汽轮机热态启动最佳温升率的确定

为进一步缩短火电机组热态启动时间,满足机组快速启动参与电网调峰的要求,以某660MW汽轮机组热态启动为例,编制程序确定不同启动阶段转子表面的蒸汽参数及换热系数,之后采用ANSYS软件对汽轮机热态启动下的转子温度场及应力场进行了数值模拟计算,分析了汽轮机转子重点监测部位热应力随温升率变化规律。并从不同温升率启动对汽轮机转子低周疲劳寿命的损耗进行分析,得到了机组热态启动的最佳温升率。研究结果可使汽轮机组热态启动下相比设计条件下缩短启动时间18%。所做工作对大型火电机组深度调峰具有一定参考价值。

工业锅炉能效测试中蒸汽采样率的探讨

饱和蒸汽湿度和过热蒸汽含盐量测量是锅炉性能试验的重要测量参数,提高湿度和含盐量测量准确度的关键是蒸汽等速采样,科学合理的蒸汽采样率可以帮助实现蒸汽等速采样。本文通过实例分析,研究了不同蒸汽引出管和采样器入口喷嘴直径对蒸汽采样率的影响,分析了蒸汽采样率的合格标准,提出了满足采样率国家标准的多孔数量。另外,针对现有国家标准GB/T 10180—2017中未提供饱和蒸汽采样率计算公式的问题,本文基于等速采样原理,推导出了单孔和多孔蒸汽采样率计算公式。本文对于饱和蒸汽和过热蒸汽采样工作具有重要的规范作用。

后续养护方式缓解蒸汽养护混凝土性能缺陷的试验研究

为研究后续养护缓解蒸汽养护造成的永久损伤,以蒸汽养护混凝土为例,设计了4种后续养护方式,测试不同后续养护方法对混凝土抗压强度、吸附系数、氯离子扩散系数和透气性等性能参数的影响。结果表明,后续养护方式对混凝土试件28 d强度增长贡献率由大到小为标准养护、饱和石灰水养护、水养护和空气养护;混凝土毛细吸附性、氯离子扩散性和透气性曲线均呈近似“L”形,即随养护时间增加而降低,且前期(龄期3 d前)下降显著,后期趋于平缓;蒸汽养护混凝土预制构件均应及时进行适当加湿养护,但不建议长时间浸泡于水环境中养护。

基于实验的直接蒸气再生CO_2系统模拟及优化

针对以乙醇胺(MEA)吸收剂为代表的传统化学吸收工艺具有再生能耗高的缺点,探究将过热蒸气直接通入再生塔与吸收剂接触再生CO2的工艺流程.通过实验和模拟分析该工艺过程中吹扫蒸气流量、蒸气过热度、富液温度、再生塔压力、填料种类对于CO2再生效果的影响.结果显示,吹扫蒸气流量,富液温度对CO2再生效果影响较为明显,而吹扫蒸气过热度对CO2再生效果影响不大.再生塔压力对再生CO2量的影响在不同的吹扫蒸气流量下呈现不同的趋势.在5种填料种类中,CY填料对CO2再生效果最好.该工艺可以有效降低热再生能耗计算过程中气化潜热部分能耗,在优化的操作条件下可以将CO2再生能耗降至每千克CO23 MJ以下.

提高CO_2膨胀烟丝内在质量的技术研究

为了提高CO2膨胀烟丝的内在质量,采用正交试验设计法分析膨胀热端工艺(气体温度、气体风速、蒸汽流量)对膨胀烟丝内在质量的影响;根据热端优化结果,分析来料烟丝水分、浸渍时间对膨胀烟丝内在质量影响。结果表明:在试验范围内,来料烟丝水分22.0%、浸渍时间80s、工艺气体温度240℃时,膨胀烟丝内在质量最佳,应用到配方中,感官质量明显提高。因此,较低的工艺气体温度,较低的来料烟丝水分、较短的浸渍时间对膨胀烟丝的内在质量是有利的。

热蒸汽处理面部对蠕形螨检出率的影响

目的了解热蒸汽处理面部对蠕形螨检出率的影响。方法选取2023年5—7月在兰州市某三甲医院皮肤科门诊就诊的215例疑似蠕形螨病的患者作为研究对象,同一患者分别在室温和热蒸汽处理面部10 min后在鼻翼两侧行蠕形螨直接刮拭法镜检。结果经热蒸汽处理后面部蠕形螨的检出率明显增高,达63.7%(137/215);而室温状态下人体蠕形螨的检出率仅为28.4%(61/215)。比较患者面部热蒸汽处理前后蠕形螨的检出率,两者差别具有显著性(χ2=54.07,P=0.00)。结论热蒸汽处理面部能显著提升蠕形螨检出率,为临床上人体蠕形螨病的实验诊断方法提供新的参考。

水蒸气对钙基CO2吸收剂煅烧-碳酸化反应的影响

利用热重分析仪和固定床反应器分别研究了水蒸气对CaCO_3煅烧和CaO碳酸化反应的影响,以及吸收剂活性提升机理.结果表明:煅烧气氛中添加水蒸气或氮气可促进CaCO_3的分解,且水蒸气促进程度更高,主要是因为水蒸气导热系数高,气固换热量更大,传热效率更高.煅烧气氛中添加水蒸气或氮气都能提升煅烧产物CaO的活性,且氮气提升的程度更高,主要是因为氮气气氛下CaCO_3颗粒烧结程度稍低.相比于纯CO_2碳酸化气氛,碳酸化气氛中添加水蒸气后,CaO活性提升了近一倍.

不同处理方式对牛蒡根多糖提取率及抗氧化活性的影响

为了研究不同处理方式对牛蒡根理化性质及抗氧化活性的影响,为牛蒡根多糖提取、产品开发提供新思路,本研究以超微粉碎、蒸汽爆破和双螺杆挤压熟化处理牛蒡根后,提取牛蒡根多糖,测定牛蒡根多糖提取液的抗氧化活性。结果表明,超微粉碎处理后牛蒡根多糖提取率最高,为36.03%。蒸汽爆破处理后牛蒡根多糖提取液DPPH自由基清除能力和羟基自由基清除能力最强,其中较未处理的牛蒡根提多糖取液DPPH自由基清除能力提高15.96%。螺杆挤压熟化处理后牛蒡根多糖提取液还原力最强,较未处理的牛蒡根多糖提取液提高15.60%。蒸汽爆破处理后菊糖的提取率最高,为34.94%。

不同加载速率下蒸养混凝土单轴压缩声发射特性研究

为研究加载速率对蒸养混凝土受压破坏过程中声发射特性的影响,针对蒸养混凝土试件开展3种加载速率工况单轴压缩试验,并利用声发射技术对试验全过程进行动态监测,分析了不同加载速率下蒸养混凝土内部声发射特征参数的变化特征。结果表明:不同加载速率下蒸养混凝土受压破坏过程的声发射振铃计数变化呈现接触期、平静期、陡增期的三阶段变化规律,随加载速率增加,振铃计数率和能量计数率峰值逐渐增大,累计振铃计数和累计能量计数逐渐减小。低加载速率下,声发射幅度分布较为稀疏,内部损伤信号多而分散;高加载速率下,声发射幅度分布较为密集,内部损伤信号少而集中。声发射Ib值随加载进程呈现上升、波动和下降的演化过程,随加载速率的增加,混凝土试件破裂模式由剪切破坏向拉伸破坏的趋势演变。