Transient Heat Transfer Study of Direct Contact Condensation of Steam in Spray Cooling Water

We conducted a transient experimental investigation of steam–water direct contact condensation in the absence of noncondensible gas in a laboratory-scale column with the inner diameter of 325 mm and the height of 1045 mm. We applied a new analysis method for the steam state equation to analyze the molar quantity change in steam over the course of the experiment and determined the transient steam variation. We also investigated the influence of flow rates and temperatures ofcooling water on the efficiency ofsteam condensation. Our experimental results show that appropriate increasing of the cooling water flow rate can significantly accelerate the steam condensation. We achieved a rapid increase in the total volumetric heat transfer coefficient by increasing the flow rate of cooling water, which indicated a higher thermal convection between the steam and the cooling water with higher flow rates. We found that the temperature ofcooling water did not play an important role on steam condensation. This method was confirmed to be effective for rapid recovering ofsteam.

CO2 assisted steam flooding in late steam flooding in heavy oil reservoirs

To improve the oil recovery and economic efficiency in heavy oil reservoirs in late steam flooding,taking J6 Block of Xinjiang Oilfield as the research object,3D physical modeling experiments of steam flooding,CO2-foam assisted steam flooding,and CO2 assisted steam flooding under different perforation conditions are conducted,and CO2-assisted steam flooding is proposed for reservoirs in the late stage of steam flooding.The experimental results show that after adjusting the perforation in late steam flooding,the CO2 assisted steam flooding formed a lateral expansion of the steam chamber in the middle and lower parts of the injection well and a development mode for the production of overriding gravity oil drainage in the top chamber of the production well;high temperature water,oil,and CO2 formed stable low-viscosity quasi-single-phase emulsified fluid;and CO2 acted as a thermal insulation in the steam chamber at the top,reduced the steam partial pressure inside the steam chamber,and effectively improved the heat efficiency of injected steam.Based on the three-dimensional physical experiments and the developed situation of the J6 block in Xinjiang Oilfield,the CO2 assisted steam flooding for the J6 block was designed.The application showed that the CO2 assisted steam flooding made the oil vapor ratio increase from 0.12 to 0.16 by 34.0%,the oil recovery increase from 16.1%to 21.5%,and the final oil recovery goes up to 66.5%compared to steam flooding after perforation adjustment.

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.

An Analysis of the Influence of Protective Films on the Inner Surfaces of CCPP Headers and Steam Pipelines on Their Thermal Stress State

At present, the main attention of researchers is paid to the deterioration of heat transfer when heating the outer surface of the pipe with the liquid or steam, flowing inside it, in the presence of films or deposits on its inner surface. However, when pipe is heating by heat carrier medium, flowing inside it, film on the inner pipe surface serve a dual protective function, protecting the pipe from corrosion and reducing its thermal stress. The article represents the results of the computational analysis of protective films influence on the thermal stressed state of headers and steam pipelines of combined-cycle power plants (CCPP) heat-recovery steam generators at different transient operating conditions particularly at startups from different initial temperature states and thermal shock. It is shown that protective films have a significant influence on the stresses magnitude and damage accumulation mainly for great temperature disturbances (for thermal shock). Calculations were carried out at various thicknesses of films and assuming that their thermal conductivity less than thermal conductivity of the steam pipelines metal.

Energy Analysis of a Combined Solid Oxide Fuel Cell with a Steam Turbine Power Plant for Marine Applications

Strong restrictions on emissions from marine power plants(particularly SOx,NOx)will probably be adopted in the near future.In this paper,a combined solid oxide fuel cell(SOFC)and steam turbine fuelled by natural gas is proposed as an attractive option to limit the environmental impact of the marine sector.The analyzed variant of the combined cycle includes a SOFC operated with natural gas fuel and a steam turbine with a single-pressure waste heat boiler.The calculations were performed for two types of tubular and planar SOFCs,each with an output power of 18 MW.This paper includes a detailed energy analysis of the combined system.Mass and energy balances are performed not only for the whole plant but also for each component in order to evaluate the thermal efficiency of the combined cycle.In addition,the effects of using natural gas as a fuel on the fuel cell voltage and performance are investigated.It has been found that a high overall efficiency approaching 60%may be achieved with an optimum configuration using the SOFC system.The hybrid system would also reduce emissions,fuel consumption,and improve the total system efficiency.

Numerical Simulation of Water Droplets Deposition on the Last-Stage Stationary Blade of Steam Turbine

Based on the method of discrete phase, the law of droplets’ deposition in the last stage stationary blade of a supercritical 600 MW Steam Turbine is simulated in the first place of this paper by using the Wet-steam model in commercial software FLUENT, where the influence of inlet angle of water droplets of the stationary blades is also considered. Through the calculation, the relationship between the deposition and the diameter of water droplets is revealed. Then, the amount of droplets deposition in the suction and pressure surface is derived. The result is compared with experimental data and it proves that the numerical simulation result obtained in this paper is reasonable. Finally, a formula of the relationship between the diameter of water droplets and the inlet angle is fit, which could be used for approximate calculation in the engineering applications.

Preparation of Hierarchically Trimodal-Porous ZSM-5 Composites through Steam-assisted Conversion of Macroporous Aluminosilica Gel with Two Different Quaternary Ammonium Hydroxides

This article presents a detailed structural study of a new spherical Mg Cl2-supported Ti Cl4 Ziegler-Natta catalyst for isotactic propylene polymerization, and researches on the relationship between catalyst structure and polymer properties. The spherical support with the chemical composition of CH3CH2 OMg OCH(CH2Cl)2 has been synthesized from a new dispersion system and is used as the supporting material to prepare Ziegler-Natta catalyst. The XRD analysis indicates that the catalyst is fully activated with δ-Mg Cl2 in the active catalyst. The far-IR spectrometric results confirm again the presence of δ-Mg Cl2 in the active catalyst. Textural property of the active catalyst exhibits high surface area coupled with high porosity. The high activity in propylene polymerization is mainly ascribed to the full activation and the porous structure of the catalyst. Scanning electron microscopy/energy dispersive spectrometer mapping results indicate a uniform titanium distribution throughout the catalyst particles. Particle size analysis shows that the catalyst has a narrow particle size distribution. The perfect spherical shape, uniform titanium distribution and narrow particle size distribution of the catalyst confirm the advantage of polymer particles production with less fines. The solid state 13 C NMR and mid-IR spectroscopic analyses indicate that there exists strong complexation between diisobutyl phthalate and Mg Cl2, which leads to the high isotacticity of polypropylene.

Models of steam-assisted gravity drainage(SAGD) steam chamber expanding velocity in double horizontal wells and its application

The development of steam chamber can be used to evaluate steam-assisted gravity drainage(SAGD) performance. The velocity of steam chamber expanding is the key parameter for evaluating the development of steam chamber. Based on SAGD technology theory and heat transfer theory, two calculation model methods, observation well temperature method and steam chamber edge method for estimating the horizontal expanding velocity of steam chamber, were presented. Through analyzing the monitoring data and numerical simulation results of a typical super heavy oil block developed by SAGD in Fengcheng oilfield in Xinjiang, NW China, the development patterns of steam chamber and temperature variation law in the observation well at different stages are determined. The observed temperature data was used to calculate steam chamber expanding velocity. The calculated chamber velocity at different time was applied to predict the temperature distribution of oil drainage zone at the edge of steam chamber and SAGD oil rate. The results indicate that temperature function of high temperature zone in the observation well temperature curve has a linear relationship with measuring depth.The characteristic section can be used to calculate key parameters such as the angle of the drainage interface, expanding edge and velocity of steam chamber. The field production data verify that the results of the two proposed methods of steam chamber growth are reliable and practical, which can provide theoretical support for the efficient development of SAGD.

Dissolution and recrystallization of perovskite induced by N-methyl-2-pyrrolidone in a closed steam annealing method

High quality perovskite films with large columnar grains are greatly desired for efficient perovskite solar cells. Here, low volatility N-methyl-2-pyrrolidone(NMP) was added in MAI/IPA solution in a two-step spin-coating method, which promoted the conversion of lead iodide to perovskite. The perovskite films were annealed by a closed-steam annealing method to prolong the recrystallization process of perovskite films assisted by the residual NMP. It leaded to high quality CH_3NH_3PbI_3 perovskite films with large columnar grains due to its enhancement of the Oswald ripening. The large grain perovskite film leaded to efficient carrier transformation and injection, and low recombination. The photovoltaic performance of the perovskite solar cells was improved significantly.

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.

Improvement of low temperature activity and stability of Ni catalysts with addition of Pt for hydrogen production via steam reforming of ethylene glycol

Hydrogen production by steam reforming of ethylene glycol(EG) at 300℃ was investigated over SiO2 and CeO2 supported Pt–Ni bimetallic catalysts prepared by incipient wetness impregnation methods. It was observed that impregnation sequence of Pt and Ni can affect the performance of catalysts apparently. Catalyst with Pt first and then Ni addition showed higher EG conversion and H2 yield owing to the Ni enrichment on the surface and the proper interaction between Pt and Ni. It was observed that although SiO2 supported catalysts exhibited better activity and H2 selectivity, CeO2 supported ones had better stability. This is attributed to the less coke formation on CeO2. Increasing Pt/Ni ratio enhanced the reaction activity, and Pt3–Ni7 catalysts with 3 wt% Pt and 7 wt% Ni showed the highest activity and stability. Ni surficial enrichment facilitated the C-C bond rupture and water gas shift reactions;and Pt addition inhibited methanation reaction. Electron transfer and hydrogen spillover from Pt to Ni suppressed carbon deposition. These combined effects lead to the excellent performance of Pt3–Ni7 supported catalysts.

Effects of Sourdough Addition on the Quality and Shelf Life of Chinese Steamed Bread

The effect of adding sourdough with lactic acid bacteria(Lactobacillus plantarum M616) on dough quality and the sensory scores, specific volume, crumb firmness, and spread ratio of resultant Chinese steamed bread were studied. The moisture content of crumb and texture characteristics of the Chinese steamed bread with sourdough during storage were analyzed. In this study, 10%,20%, 30%, and 40% of sourdough addition was investigated. The sourdough starter resulted in significant decrease in the water absorption, development time, stability, and farinograph quality number of the dough. The addition of sourdough improved the quality of Chinese steamed bread such as improving the sensory scores and specific volume, decreasing the crumb firmness, and a lower spread ratio was observed with an increase in the sourdough concentration up to 30%. Sourdough addition delayed a fast decrease in the moisture content of the Chinese steamed bread crumb during storage. The texture profile analysis of the bread crumb indicated that the addition of sourdough improved the quality and delayed the staling speed of Chinese steamed bread during storage.Moreover, inclusion of 30% sourdough produced the best protective effect on product staling.

Study and Strategy on Expansion of Steam Cracking Unit to 650 kt/a at Yanshan Petrochemical Company

After having expanded its capacity from 300 kt/a to 450 kt/a in 1994, the steam cracking unit of Yanshan Petrochemical Company was still experiencing such problems as low feedstock flexibility, high energy consumption and smaller production capacity as compared to other ethylene units constructed in the same time. In order to fully improve technical capability, reduce energy consumption, improve feedstock flexibility and increase production capacity of steam crackers, a lot of technical transform schemes on steam cracking were studied and compared with attention focused on the feasibility, safety, operability of the related revamp schemes, as well as the advanced nature and economical features. The transform scheme decided includes following projects. For the pyrolysis quench compression system, the pyrolysis gasoline fractionation tower is retrofitted on the site, quench water tower, pyrolysis gas compressor and steam turbine are replaced by new ones respectively. For the separation system a low pressure methane removal technology is adopted with the demethanizer tower replaced, coupled with the C 3 catalytic rectification/hydrogenation technology, while the high pressure depropanizer is replaced with addition of a propylene rectification tower. The fractionation flow sheet and equipment are adjusted with addition of a propylene compressor and compressor for binary mixture of methane ethylene cooling agents. The revamped complex has expanded the ethylene capacity to the target of 660 kt/a with the actual capacity reaching 710 kt/a, remarkably reduced the energy consumption, and is capable of using naphtha, light diesel fuel, heavy diesel fuel and the hydrocracked tail oil as the steam cracking feedstock. This project is the first to apply refrigeration by means of a mixed cooling agent and has succeeded in using C\-3 catalytic rectification/hydrogenation technology, which has given an impetus to the progress of steam cracking industry in the world.

Nutritional evaluation of different cultivars of potatoes(Solanum tuberosum L.) from China by grey relational analysis(GRA) and its application in potato steamed bread making

Chemical composition(moisture,protein,starch,ash,fiber,fat),vitamins(vitamin C,vitamin B1,vitamin B2),total polyphenol content,antioxidant capacity,minerals,and amino acid of 14 potato cultivars in China were evaluated.The results indicated that all parameters varied significantly among different potato cultivars.The total starch,crude protein and fat content ranged between 57.42–67.83%,10.88–14.10% and 0.10–0.73% dry weight(DW),respectively.Moreover,the consumption of potato increased remarkably the dietary intake of vitamins,K,Mn and Cu.In addition,the chemical score of amino acid varied considerably between different cultivars,which ranged from 54(Neida 3 and Neida 41) to 71(Neida 34).Grey relational analysis(GRA) indicated that Neida 26 exhibited the most comprehensive nutritional values among potato cultivars,followed by Neida 42.Different potato flours had a significant effect on the quality parameters of potato steamed bread(PSB),Neida 26 and Neida 34 were more suitable for making PSB.

Research on the steam–gas pressurizer model with Relap5 code

Steam–gas pressurizers are self-pressurizing, and since steam and noncondensable gas are used to sustain their pressure, they experience very complicated thermal–hydraulic phenomena owing to the presence of the latter. A steam–gas pressurizer model was developed using Relap5 code to investigate such a pressurizer's thermal–hydraulic characteristics.The important thermal–hydraulic processes occurring in the pressurizer model include bulk flashing, rainout, wall condensation with noncondensable gas, and interfacial heat and mass transfer. The pressurizer model was verified using results from insurge experiments performed at the Massachusetts Institute of Technology. It was found that noncondensable gas was one of the important factors governing the pressure response, and the accuracy of the developed model would change with different mass fractions and types of noncondensable gas.

Design of Steam Turbine for Electric Power Production Using Heat Energy from Palm Kernel Shell

The steam turbine is a prime mover that converts kinetic energy in steam into rotational mechanical energy through the impact or reaction of the steam against the blades. The aim of this study is to design a steam turbine for a small scale steam power plant with target of producing electricity. The turbine is driven by the heat energy from palm kernel shells as a renewable energy source obtained at a lower or no cost. The study was concentrated on design of turbine elements and its validation using computer packages. Specifically, the microturbine design was limited to design, modeling, simulation and analysis of the rotor, blades and nozzle under the palm kernel shell as fuel for the micro power plant. In blade design, stress failures, efficiency and blade angle parameters were considered. In casing volume design, the overall heat transfer and mean temperature, and different concepts were applied. The thermal distribution on stator and rotor was considered in order to determine its level of tolerance. The design software packages used for design validation were Solidworks and Comsol Multiphysics for analysis. Simulation results showed that the designed steam turbine can adequately tolerate change in stress/load, torsion/compression, temperature and speeds.

Reaction parameters influence on the catalytic performance of copper-silica aerogel in the methanol steam reforming

Steam reforming of methanol was carried out on the copper-silica aerogel catalyst.The effects of reaction temperature,feed rate,water to methanol molar ratio and carrier gas flowrate on the H_2 production rate and CO selectivity were investigated.M ethanol conversion was increased considerably in the range of about 240-300,after which it increased at a slightly lower rate.The used feed flowrate,steam to methanol molar ratio and carrier gas flowwere 1.2-9.0 m L/h,1.2-5.0 and 20-80 m L/min,respectively.Reducing the feed flowrate increased the H_2 production rate.It was found that an increase in the water to methanol ratio and decreasing the carrier gas flowrate slightly increases the H2production rate.Increasing the water to methanol ratio causes the lowest temperature in which CO formation was observed to rise,so that for the ratio of 5.0 no CO formation was detected in temperatures lower than 375℃.In all conditions,by approaching the complete conversion,increasing the main product concentration,increasing the temperature and contact time,and decreasing the steam to methanol ratio,the CO selectivity was increased.These results suggested that CO was formed as a secondary product through reverse water-gas shift reaction and did not participate in the methanol steam reforming reaction mechanism.

Study on Valve Management of DEH for Steam Turbine

Valve management is one of the major functions of DEH for steam turbine. It has an important practical significance for the security and economy of the steam turbine. This paper starts from the valve configuration figure of the domestic-type 300 MW steam turbine, and then makes a simple comparison between the two types of valve governing modes. In order to realize the valve control, the structure of control system has been established, in which the roles of the mathematical functions are discussed. On the basis of the experiment of valve flow characteristic, this article carries out a quantitative study on the functions of the valve management and the parameter tuning method. Through a serious corrections, the sequence valve flow characteristic curve is obtained, which can provide significant guidance on the research of valve management of the similar steam turbines.

Calculation of Thermal Stress and Fatigue Life of 1000 MW Steam Turbine Rotor

The paper calculated the temperature and stress fields of 1000 MW ultra-supercritical steam turbine rotors which start in cold condition using the finite element calculation program (ANSYS). After getting rotor stress field, the paper use the general slope method to estimate the low cycle fatigue life loss, the rest of the conditions can be calculated in this method.

Clinical Research on Alleviating Pain for Patients with Ankylosing Spondylitis and Their Active Function by Acupuncture with Chinese Medicine Fuming and Steaming

OBJECTIVE: To investigate clinical effect of acupuncture combined with TCM fumigation on pain and active function improvement in patients with ankylosing spondylitis. METHODS: 42 patients with ankylosing spondylitis were selected in hospital from October 2016 to October 2017, who were randomly divided into 2 groups by number table method. 21 patients received conventional treatment as control group. 21 patients combined with acupuncture, TCM fumigation treatment as observation group. Clinical indicators, activity function, pain scores were evaluated before and after treatment. RESULTS: Erythrocyte sedimentation rate, C reactive protein, alkaline phosphatase, macrophage migration inhibitory factor, BASDAI score, BASFI score, VAS score after treatment decreased in two groups compared with before treatment(P<0.05). Chest mobility, lumbar pitch, Schober test, occipital wall distance, lumbar lateral flexion after treatment increased in two groups compared with before treatment(P<0.05). Refers to distance, morning stiffness time, rump length after treatment reduced in two groups compared with before treatment(P<0.05). Erythrocyte sedimentation rate, C reactive protein, alkaline phosphatase, macrophage migration inhibitory factor, BASDAI score, BASFI score, VAS score in observation group were lower than control group after treatment(P<0.05). Chest mobility, lumbar pitch, Schober test, occipital wall distance, lumbar lateral flexion in observation group were higher than control group after treatment(P<0.05). Refers to distance, rump length in observation group were smaller than control group after treatment(P<0.05). Morning stiffness time in observation group was less than control group after treatment(P<0.05). CONCLUSIONS: Acupuncture combined with TCM fumigation can significantly improve pain and active function in patients with ankylosing spondylitis, which is worthy of clinical promotion.