Effect of long reaction distance on gas composition from organic-rich shale pyrolysis under high-temperature steam environment

When high-temperature steam is used as a medium to pyrolyze organic-rich shale,water steam not only acts as heat transfer but also participates in the chemical reaction of organic matter pyrolysis,thus affecting the generation law and release characteristics of gas products.In this study,based on a long-distance reaction system of organic-rich shale pyrolysis via steam injection,the effects of steam temperature and reaction distance on gas product composition are analyzed in depth and compared with other pyrolysis processes.The advantages of organic-rich shale pyrolysis via steam injection are then evaluated.The volume concentration of hydrogen in the gas product obtained via the steam injection pyrolysis of organic-rich shale is the highest,which is more than 60%.The hydrogen content increases as the reaction distance is extended;however,the rate of increase changes gradually.Increasing the reaction distance from 800 to 4000 mm increases the hydrogen content from 34.91%to 69.68%and from 63.13%to 78.61%when the steam temperature is 500℃ and 555℃,respectively.However,the higher the heat injection temperature,the smaller the reaction distance required to form a high concentration hydrogen pyrolysis environment(hydrogen concentration>60%).When the steam pyrolysis temperature is increased from 500℃ to 555℃,the reaction distance required to form a high concentration of hydrogen is reduced from 3800 to 800 mm.Compared with the direct retorting process,the volume concentration of hydrogen obtained from high-temperature steam pyrolysis of organic-rich shale is 8.82 and 10.72 times that of the commonly used Fushun and Kivite furnaces,respectively.The pyrolysis of organic-rich shale via steam injection is a pyrolysis process in a hydrogen-rich environment.

ExperimentonPerformanceofLow-TemperatureExhaustSteamReclamation

针对不同的喉嘴距、面积比，实验研究了不同的进水压力、进水温度和出水压力对低温乏汽回收利用装置性能的影响规律．发现在进水压力为0．14～O．50MPa、进水温度为23～60℃、出水压力为0．096-0．110MPa，以及4种喉嘴距、3种面积比的实验条件范围内，随着喉嘴距和面积比的增加，加热温升和流量比先增大后减小，得到最佳归一化喉嘴距L=4．50，以及最佳面积比m=6．25，使得加热温升和流量比最大．同时，加热温升和流量比均随着进水压力和进水温度的增加而减小，当出水压力升高时，装置性能变差，加热温升和流量比均减小．

Preference-based multiobjective artificial bee colony algorithm for optimization of superheated steam temperature control

In order to incorporate the decision maker＇s preference into multiobjective optimization a preference-based multiobjective artificial bee colony algorithm PMABCA is proposed.In the proposed algorithm a novel reference point based preference expression method is addressed.The fitness assignment function is defined based on the nondominated rank and the newly defined preference distance.An archive set is introduced for saving the nondominated solutions and an improved crowding-distance operator is addressed to remove the extra solutions in the archive.The experimental results of two benchmark test functions show that a preferred set of solutions and some other non-preference solutions are achieved simultaneously.The simulation results of the proportional-integral-derivative PID parameter optimization for superheated steam temperature verify that the PMABCA is efficient in aiding to making a reasonable decision.

Neuro-fuzzy generalized predictive control of boiler steam temperature

Power plants are nonlinear and uncertain complex systems. Reliable control of superheated steam temperature is necessary to ensure high efficiency and high load-following capability in the operation of modem power plant. A nonlinear generalized predictive controller based on neuro-fuzzy network （NFGPC） is proposed in this paper. The proposed nonlinear controller is applied to control the superheated steam temperature of a 200MW power plant. From the experiments on the plant and the simulation of the plant, much better performance than the traditional controller is obtained,

Hydrogen production at intermediate temperatures with proton conducting ceramic cells:Electrocatalytic activity,durability and energy efficiency

Proton conducting ceramic cells(PCCs)are an attractive emerging technology operating in the intermediate temperature range of 500 to 700℃.In this work,we evaluate the production of hydrogen at intermediate temperatures by proton conducting ceramic cell electrolysis(PCCEL).We demonstrate a highperformance steam electrolysis owing to a composite positrode based on BaGd_(0.8)La_(0.2)Co_(2)O_(6-δ)(BGLC1082)and BaZr0.5Ce0.4Y0.1O3-δ(BZCY541).The high reliability of PCCEL is demonstrated for 1680 h at a current density as high as-0.8 A cm^(-2)close to the thermoneutral cell voltage at 600℃.The electrolysis cell showed a specific energy consumption ranging from 54 to 66 kW h kg^(-1)that is comparable to state-of-the-art low temperature electrolysis technologies,while showing hydrogen production rates systematically higher than commercial solid oxide ceramic cells(SOCs).Compared to SOCs,the results verified the higher performances of PCCs at the relevant operating temperatures,due to the lower activation energy for proton transfer comparing with oxygen ion conduction.However,because of the p-type electronic conduction in protonic ceramics,the energy conversion rate of PCCs is relatively lower in steam electrolysis.The faradaic efficiency of the PCC in electrolysis mode can be increased at lower operating temperatures and in endothermic conditions,making PCCEL a technology of choice to valorize high temperature waste heat from industrial processes into hydrogen.To increase the faradaic efficiency by optimizing the materials,the cell design,or the operating strategy is a key challenge to address for future developments of PCCEL in order to achieve even more superior techno-economic merits.

Outlet Temperature Correlation and Prediction of Transfer Line Exchanger in an Industrial Steam Ethylene Cracking Process

Predicting the best shutdown time of a steam ethylene cracking furnace in industrial practice remains a challenge due to the complex coking process. As well known, the shutdown time of a furnace is mainly determined by coking condition of the transfer line exchangers （TLE） when naphtha or other heavy hydrocarbon feedstocks are cracked. In practice, it is difficult to measure the coke thickness in TLE through experimental method in the complex industrial situation. However, the outlet temperature of TLE （TLEOT） can indirectly characterize the coking situation in TLE since the coke accumulation in TLE has great influence on TLEOT. Thus, the TLEOT could be a critical factor in deciding when to shut down the furnace to decoke. To predict the TLEOT, a paramewic model was proposed in this work, based on theoretical analysis, mathematic reduction, and parameters estimation. The feasibility of the proposed model was further checked through industrial data and good agreements between model prediction and industrial data with maximum deviation 2% were observed.

Application of PID Controller Based on BP Neural Network in Export Steam’s Temperature Control System

By combining the Back-Propagation （BP） neural network with conventional proportional Integral Derivative （PID） controller, a new temperature control strategy of the export steam in supercritical electric power plant is put forward. This scheme can effectively overcome the large time delay, inertia of the export steam and the influencee of object in varying operational parameters. Thus excellent control quality is obtaitud. The present paper describes the development and application of neural network based controller to control the temperature of the boiler＇s export steam. Through simulation in various situations, it validates that the control quality of this control system is apparently superior to the conventional PID control system.

Analyzing the effect of steam quality and injection temperature on the performance of steam flooding

The heavy oil reservoirs are currently mainly targeted by thermal enhanced oil recovery technologies,particularly,steam flooding.Steam flooding is carried out by introducing heat into the reservoir to unlock the recovery of heavy oil by reducing oil viscosity.Several investigations were carried out to improve oil recovery by steam flooding.Most recently,high steam flooding is reported as an effective approach to improve recovery in high pressure heavy oil reservoirs.The oil recovery from steam flooding is sub-stantially affected by the steam quality and injection temperature.In this study,an attempt was made to look into the integration of parameters,i.e.steam quality and injection temperature upon steam flooding on oil recovery by using a simulation approach via ECLIPSE.The results obtained indicated that high temperature along with the moderate value of steam quality gives the best result regarding oil recovery for steam flooding in an economical way.

Low CO content hydrogen production from oxidative steam reforming of ethanol over CuO-CeO_2 catalysts at low-temperature

CuO-CeO2 catalysts were prepared by a urea precipitation method for the oxidative steam reforming of ethanol at low-temperature.The catalytic performance was evaluated and the catalysts were characterized by inductively coupled plasma atomic emission spectroscopy,X-ray diffraction,temperature-programmed reduction,field emission scanning electron microscopy and thermo-gravimetric analysis.Over CuOCeO2 catalysts,H2 with low CO content was produced in the whole tested temperature range of 250–450 C.The non-noble metal catalyst 20CuCe showed higher H2production rate than 1%Rh/CeO2 catalyst at 300–400 C and the advantage was more obvious after 20 h testing at400 C.These results further confirmed that CuO-CeO2 catalysts may be suitable candidates for low temperature hydrogen production from ethanol.

Coupling of Wind Energy and Biogas with a High Temperature Steam Electrolyser for Hydrogen and Methane Production

The production of environment friendly green fuels is based on energy from renewable sources. Among the renewable sources, wind power is a very growing power technology. An example which has been discussed very widely is hydrogen which is an ideal fuel for a fuel cell. Hydrogen is the energy of the future. It will be used as energy carrier as well as reactant to produce green fuels, like methane which is easier to handle. Direct coupling of a High Temperature Steam Electrolyser (HTSE) with a wind turbine can be used to generate hydrogen. Indeed performing the electrolysis process at high temperatures offers the advantage of achieving higher efficiencies compared to the conventional water electrolysis. The hydrogen produced can be then reacted with the CO2 content of biogas to form methane as green fuel. Thus, the concept presented in this paper illustrates the potential of the HTSE technology coupled with a wind turbine, this system being combined with biogas in a methanation unit. Developing scenarios and flow sheets and using mass and energy balance, the technical performance of the concept is investigated. A plant capacity of 10 MWel is considered. An annual production of 1104 metric tons per year (Mt/a) hydrogen and thus of 5888 Mt/a methane is reached. The overall plant efficiency is calculated to be 38%. The combination of wind power and biogas offers thus many advantages which can facilitate the penetration of the wind resource and the progression to the hydrogen economy.

Methane Production via High Temperature Steam Electrolyser from Renewable Wind Energy: A German Study

The transformation of the energy supply needs further development of energy storage technologies in order to integrate the fluctuating renewable energy. The conversion of renewable wind power into green methane offers a technical approach with the necessary storage and transport capacities. Thus, the concept of Power-to-Gas which is illustrated here by the coupling of wind energy with a High Temperature Steam Electrolyser (HTSE) and a methanation unit enabling the production of green fuel like hydrogen and methane is presented is this paper. In fact, hydrogen can be used as energy carrier as well for the production of green fuels, like methane which is simpler to store and to transport and which can be thus used as storage medium for the stabilization of the electrical power supply as well as fuel for transport and heat sector. Its production using high temperature electrolysis is able to reduce the carbon dioxide emissions if performed with renewable resources. This is the case if the electricity needed for the HTSE comes from a wind turbine and the CO2 needed for the methanation step comes from biogas. For such a plant, the location and the boundary conditions have a great importance. Thus, this study considers the coupling of a HTSE with a wind turbine and a methanation reactor, and focuses about the site selection, depending of the geographical and economic considerations. The study is limited first to the European area. Schleswig-Holstein is found as a very good location for this plant. It is one of the regions with the largest wind reserves in Germany. This region has also available a lot of biogas and meets all the other necessary requirements.

Monitoring of steam chamber in steam-assisted gravity drainage based on the temperature sensitivity of oil sand

Thermosensitivity experiments and simulation calculations were conducted on typical oil sand core samples from Kinosis,Canada to predict the steam chamber development with time-lapse seismic data during the steam-assisted gravity drain-age(SAGD).Using an ultrasonic base made of polyether ether ketone resin instead of titanium alloy can improve the signal en-ergy and signal-to-noise ratio and get clear first arrival;with the rise of temperature,heavy oil changes from glass state(at-34.4℃),to quasi-solid state,and to liquid state(at 49.0℃)gradually;the quasi-solid heavy oil has significant frequency dis-persion.For the sand sample with high oil saturation,its elastic property depends mainly on the nature of the heavy oil,while for the sand sample with low oil saturation,the elastic property depends on the stiffness of the rock matrix.The elastic property of the oil sand is sensitive to temperature noticeably,when the temperature increases from 10℃ to 175℃,the oil sand samples decrease in compressional and shear wave velocities significantly.Based on the experimental data,the quantita-tive relationship between the compressional wave impedance of the oil sand and temperature was worked out,and the tem-perature variation of the steam chamber in the study area was predicted by time-lapse seismic inversion.

Model Identification Based on Subspace Model Identification of Main Steam Temperature in Ultra-Supercritical Coal-Fired Power Unit

Ultra-supercritical(USC) unit is more and more popular in coal-fired power industry.In this paper,closed-loop identification based on subspace model identification(SMI) is introduced for superheated steam temperature system of USC unit.Closed-loop SMI is applied to building step response model of the unit directly.The parameters selection method is proposed to deal with the parameter sensitivity and improve the reliability of the model.Finally,the model is used in model identification of real USC unit.

Oxidation behaviors of wrought nickel-based superalloys in various high temperature environments

Oxidation characteristics of Alloy 617 and Haynes 230 at 900 oC in simulated helium environment,hot steam environment containing H2 as well as in air and pure helium conditions were investigated.Compared to air condition,the oxidation rate of Alloy 617 was not significantly affected in helium and hot steam environments,while Haynes 230 showed lower oxidation rate in helium environment.On the other hand,the oxide morphology and structure of Alloy 617 were strongly affected by the environments,but those of Haynes 230 were less dependent on the environments.For Haynes 230,a Cr2O3 inner layer and a protective MnCr2O4 outer layer were formed in all environments,which contributed to the better oxidation resistance.As the mechanical properties,such as creep and tensile properties,were significantly affected by the oxidation behaviors,surface treatment methods to enhance oxidation resistance of these alloys should be developed.

Reclamation of CO_(2) sodium silicate used sands by steam leaching

The bond film on the surface of the CO_(2) sodium silicate used sands is not easy to decompose,therefore,it is difficult to reclaim used sands.A new reclamation method of CO_(2) sodium silicate used sands was developed by steam leaching,which can reduce the water consumption of reclamation and improve the removal effect of sodium silicate bond film.Firstly,the leaching effect of the sodium silicate sands after 20/200/400/600/800/1,000°C heat preservation treatment was simulated.Furthermore,the influence of the leaching time on the removal effect of the sodium silicate bond film was studied.Finally,the casting properties of the reclaimed sands after the leaching reclamation treatment were tested.The results show for simulated used sands after 30 min of steam leaching,the removal ratio of the alkali exceeds 84.1%,the removal ratio of silicate is 86.2%,and the removal ratio of carbonate is 93.6%.The removal rate of alkali,silicate and carbonate is relatively low in the leaching time of 30-50 min.Considering the reclamation effect and cost,the leaching time is controlled in 30 min.Water consumption is only 60%of the mass of used sands for 30 min steam leaching,while it is 200%for wet reclamation.Morphological analysis shows that most of the hazardous substances in the used sands are removed in 30 min steam leaching,and the reclaimed sands surface after steam leaching in 50 min is as smooth as new sands.After 30 min of steam leaching,the alkali removal effect of the factory used sands can reach 81.5%,the water consumption by the steam leaching reclamation is 58%of the mass of the used sand,which is similar to the result of simulated used sands.The performance of reclaimed sands obtained after 30 min steam leaching is better than that of new sands when the amount of sodium silicate added is 6%of the mass of the reclaimed sands and the CO_(2) blowing time is 15 s:the 24 h ultimate compressive strength of reclaimed sands is 5.6 MPa(equated with new sands),and the collapsibility compressive strength is 5.2 MPa,which is lower than the collapsibility compressive strength of new sands(7.7 MPa).This indicates that the reclamation of CO_(2) sodium silicate used sands by steam leaching is a feasible method.

3种灭菌方式对磁外科器件磁通量的影响及灭菌成本分析

目的 分析压力蒸汽、低温等离子及环氧乙烷3种灭菌方式对磁外科器件磁通量的影响及其灭菌成本。方法234件不同规格型号磁外科器件-磁环,配对编号标记后随机分为A组、B组和C组,每组78件(39对),其中A组使用压力蒸汽灭菌,B组使用低温等离子灭菌,C组使用环氧乙烷灭菌,每对器件按灭菌规范进行包装;测量3组磁环灭菌前后磁通量,对单包灭菌成本和灭菌时间比较分析。结果 3种灭菌方式对磁外科器件磁通量的影响差异无统计学意义(P>0.05),每种灭菌方式灭菌前后的磁通量有统计学差异(P<0.001);灭菌成本:A组为(1.96±0.16)元,B组(23.17±0.32)元、C组(8.16±0.18)元,差异有统计学意义(P<0.01);灭菌时间:A组为(65.21±3.36)min, B组(45.46±1.39)min, C组(1 020.38±12.21)min,差异具有统计学意义(P<0.01)。结论 3种灭菌方式对磁外科器件的磁通量没有影响。压力蒸汽灭菌法单包成本最低,低温等离子单包灭菌成本最高,环氧乙烷灭菌时间最长。压力蒸汽应为磁外科手术器件的首选灭菌方法。

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。

高温气冷堆热态功能试验中一回路加热动态特性研究

高温气冷堆反应堆压力容器堆内构件由石墨和碳化硼烧结陶瓷材料组成,热态功能试验过程中需对一回路堆内构件进行加热除湿。针对高温气冷堆一回路热试系统特点,采用COMSOL Multiphysics 5.4计算软件构建了压力容器、蒸汽发生器和主氦风机三维数值模型,并通过示范工程加热试验值验证了模型的可靠性,并获得了一回路加热过程中温度场动态特性。为了解决高温气冷堆示范工程一回路首次加热效率低的问题,提出了将辅助蒸汽通入到蒸汽发生器,并动态调整辅助蒸汽运行参数来加热一回路氦气的方法,结果表明:相较于主氦风机单独加热方式,外加辅助蒸汽热源可节省加热时间约31.3 h,同时可将堆芯最终平衡温度由250℃提高至265℃;在满足运行准则的前提下,更有利于碳砖和石墨堆内构件的除湿。该研究结果为高温气冷堆一回路热试提供了有力支持。

不同热处理方式对小麦粉特性及其蒸饼品质的影响

目前蒸饼的制作大多采用传统的半烫面工艺,工序较为复杂,为解决这一问题,该研究采用不同热处理方式(蒸汽处理、微波处理、干热处理)对小麦粉进行热处理,研究了不同处理方式对小麦粉的糊化特性、热机械学特性、微观结构等的影响,并将处理后的小麦粉添加到未处理的小麦粉中制成蒸饼,考察了所制得的蒸饼的水分分布、质构特性及感官品质。结果表明:3种热处理的适当处理时间都可以提高小麦粉的黏度和回生值;经干热处理和微波处理后的小麦粉的破损淀粉含量高于经蒸汽处理的小麦粉。3种热处理小麦粉的添加均可以提高面团的吸水率,蒸汽处理小麦粉的添加使面团耐揉性降低、蒸煮稳定性提高,微波和干热处理小麦粉的添加使面团的耐揉性和内部结构稳定性提高。适当处理时间的热处理小麦粉的添加可以提高蒸饼的结合水含量、硬度、弹性和咀嚼性等。其中,经蒸汽处理40 min、微波处理2 min和干热处理30 min后的小麦粉的添加制得的蒸饼有相对适中的强韧性、较高的结合水含量和感官评分。该研究结果表明添加热处理后的小麦粉代替传统的烫面工艺制作高品质蒸饼具有可行性,同时能够为蒸饼的工业化生产提供相应的基础数据和一定的理论指导。

某600MW机组锅炉主汽出口抽汽方案安全性分析

供热抽汽是形势所趋,本文以某60万千瓦锅炉主汽出口管道最大抽汽量方案进行核算,分别就30%、40%和50%锅炉负荷、在保证发电量不变的基础上,通过壁温计算模型的建立,最终理论计算出三个负荷下最大的理论抽汽量,可为后续供热抽汽改造方案设计提供一些参考。