Lignite high bed super-heated steam pre-drying technology is integrated into power plant system to generate electricity. The economy of the system is analyzed and calculated by the effective heat drop method. Take 330 MW sub-critical units for example, the reduced standard coal consumption is 4.32g/kwh when the fuel is blended with 30% pre-dried lignite. This technology can improve the calorific value of lignite, and reduce CO2 emissions and fuel consumption, also improve power plant efficiency by reducing the power losses of the auxiliary system.
According to the analysis of lignite reserves and properties, we find that it is urgent to improve lignite quality. So we introduce the lignite quality improvement technology as well as their utilization situation, merit and demerit at home and abroad, and propose a new technology to improve the quality of lignite.
The author designs a multi-effect distillation system heated directly by solar energy in this paper. This system combines direct solar heating system and multi-effect distillation system together to desalinate brackish water. The author has made some analogy calculations on the water production rate and the heat analysis of evaporators about this system. The result indicates that the water production rate per day can reach 40 kg, while the effl uent temperature of the direct solar heating system reaches 60℃. When the number of multieffect is 4, the cost of fresh water is 5-7RMB. So it is feasible to use the multi-effect distillation system heated directly by solar energy in areas where the solar energy is abundant but the fresh water is lacking.
This study prepared microcapsules in different size and of different vitamin E content by using microcapsules apparatus(BUCHI, B-395). And the effects of size and vitamin E content on the release rate of vitamin E were analyzed. It is found that the size of the microcapsules were about twice as the diameter of the nozzles. It's also concluded that the smaller the size of microcapsule is, the faster the release rate for the dried product and the higher the release ratio. Therefore, the higher the VE content in the dried product, the faster the release process towards saturation with better release property.
This paper studied the drying characteristics and drying model of SiC ultrafine powder pellet under different temperatures(130℃,150℃ and 170℃) and different air velocities(2m/s and 3m/s) on experimental drying devices.The results show that the drying process of SiC ultrafine powder pellet is divided into three stages:rising speed stage,constant speed stage and falling speed stage.The drying time of the rising speed stage is about 20-30min;the drying time of the constant speed stage is about 50-80min;and the drying time of the falling speed stage is about 180-210min.The higher the hot air temperature,the higher the drying rate of the constant speed stage is and the larger the slope of the drying rate curve in the falling rate period is.When the wind speed is higher than 2m/s,the drying rate is not changing obviously.Through the analyses of the experimental data of drying SiC ultrafine powder pellet under different temperatures and velocities and the 8 frequently used fitting models,it is found that the goodness of fit of the modified Page model(Ⅱ) is the best and this model can reflects the drying characteristics of SiC ultrafine powder pellet under different temperatures and air velocities.
The drying process was divided into two processes: heating process and cooling process because of the non-linear and strong coupling characteristics of heat pump drying system. Therefore, the temperature control strategy should be divided into the heating and cooling fuzzy controls. Both of the temperature and relative humidity of the drying air are key factors affecting the quality of dryed materials. In order to improve the quality of dryed materials, a humidity fuzzy control strategy was promoted based on the control of temperature. From the results of experiment, the control strategy gives high temperature and relative humidity precision: the deviation of of temperature control is ±0.8℃ and the relative humidity is ±3%.
The flow around a circular cylinder under the Reynolds numbers of 500, 750 and 1000 was studied by numerical simulation. The velocity and vorticity fields at different moments of the initial and steady stage of flow were given. And the spatial-temporal evolutions of vortex generation and shedding were obtained. The simulation results show that, as the Reynolds number increases, the times required to reach the steady stage of flow and to go through a flow cycle shorten, and the frequency of vortex shedding and the capability of vortex transport along the flow direction increase.
In this paper, theories of gas-solid two phase flow was used for a full analysis of acceleration motion and deceleration motion of the solid particles in impulse pneumatic dryer on the base of Xia Chengyi method. The altitude equation and time equation of acceleration motion and deceleration motion was built. The equations were built in different segment of the impulse pneumatic dryer and calculated in different Re region. The analysis of motion trajectory of solid particles provides the theoretic support for the model establishment of cross-domain motion and exploitation for new combination of different dryers.
This paper introduces a manufacture method which about the blade ruled in the 5-axis NC milling. First on the modeling method about blade, the 3D modeling is based on data points which is obtained through the wood-line map and axial projection map. Then make a principle tool path planning according to blade molding. Make work table rotates to the right angle so that the cutting tool can go along the axis cutting line. Then detailed the calculating method about tool distance and the beginning, ending points coordinates of tool. It is calculated through the B-spline curve interpolation methods to seek new coordinates of data points. Final preparation tool path, and processing simulation .
In this paper,a porosity determination method was proposed for the freeze-dried potato based on the image processing method.The potato was first frozen using different methods and then was vacuum-dried.Scanning Electron Microscope(SEM) photographs were taken for the sliced dried potato and then were converted into the black-white images by image processing.By accumulating the area ratio of the black pixel in the image,the porosity of the freeze-dried potato can be determined.It was found that the porosity varies between 0.28 and 0.61 and the sample size plays a important role in the porosity in this experiment.
The heat-pump drying process of Dioscorea opposite slices was studied in this paper. The drying process was proposed to improve the drying efficiency and product quality. The influences of the heat-pump drying temperature, air velocity, and slice thickness on the drying curve, brightness, rehydration rate were investigated. The experimental results showed that the temperature, air velocity, slice thickness have a significant effect on the drying rate in heat-pump drying process, and the optimal drying parameters were heat-pump temperature 50℃,air velocity 1.0 m/s, and slice thickness 5 mm. The L value and rehydration rate of the dried Dioscorea opposite slices were 82.07 and 85.08%, respectively.
With cantaloupe as testing material in this article, using nitrogen as drying medium to reduce the oxygen concentration in equipment, the drying rate, brightness, Vc content and total phenol content of heat pump drying cantaloupe slices were studied by drying temperature, slice thickness, oxygen concentration and wind speed. The orthogonal experiment results showed that the optimum drying process parameters are temperature-50℃, the slice thickness-5mm, oxygen volume fraction-5%. The moisture content of dried cantaloupe slice is7.42%, brightness value of L is 71.28, ascorbic acid content is 21.06 mg/100g, and total phenol content is 8.46mg/100g.
Vacuum freeze dried products have good quality and are widely accepted, but this process has lower drying rate and higher energy consumption, restricting its further applications in other not high value-added products. In this paper, based on a proposed combination of infrared assisted heating and shelf conduction, the heating efficiency is improved. On the other hand, a control system for this infrared assisted freeze dryer was developed to realize the desirable freezing and heating of materials and user-friendly operation.
In order to carry out residence time calculation study of material in a directly-heated rotary dryer with ideal lifting flights, according to the material scatter well-distributed state in the drum with lifting flights, a set of equations has been established to describe the surface profile of ideal lifting flights,the lifting flights holdup with the drum rolling in the different position has been derived, then the actual motion of material was studied in a directly-heated rotary dryer, a set of mathematical models has been established to describe the motion of material in drum, the residence time of material in drum has been derived, the existing residence time formulas have been revised, A kind of reference is proposed for residence time calculation of material in a directly-heated rotary dryer with ideal lifting flights.
Computational fluid dynamics(CFD) is an important method to describe the numerical solution of the flow field quantitatively by using the computer numerical simulation and image display, and thus to analyze the physical problems. It have the characteristics of both theoretical and practical, the main purpose of the CFD is to predict the flow velocity field, temperature field, concentration field effectively by using numerical simulation. The application and development prospect of the CFD numerical simulation in food drying process and design of the drying equipment are explored in this paper.
Microwave vacuum drying is a new technology, in which the dried material was heated and dried by using microwave energy under a vacuum condition. In the experiment, we studied the rehydration ratio and vitamin C content of dried kiwi slices. Based on single factor, we analyzed the effects of microwave power, material thickness, drying chamber pressure on drying characteristics of kiwi slices using 3 factors and 3 levels by quadratic regression orthogonal experiments. Results showed that in the microwave power of 800W, slice thickness of 4mm, drying chamber pressure of 0.04 MPa conditions, kiwi slices had the best dried qualities, so the microwave vacuum drying parameters on quality of kiwifruit slices are resulted.
The paper experimentally investigated the influences of power and resident time on the drying characteristics of jackfruit pulp with microwave drying device.According to the drying curve,a mathematical model of jackfruit pulp drying was established by using the multiple regression method. Through the orthogonal experiment,it showed that the power was the most significant influencing the drying productivity of jackfruit,followed by the input rate and drying time.
Base on the characters of radioactive wastes concentrates in nuclear power plants, the simulated concentrates were chosen as the research object.The preliminary study on waste concentrates treatment by drying technique was done,The products humidity after drying is less than 15%,the mass after drying is about 20%,and the volume reduction ratio is almost 4.5.The results showed that treatment concentrates by drying technology should be deep study as a volume reduced technology.
Aerogels are novel and light nanoporous solid materials with three dimensional network structures.They have potential applications in variety technological areas and have attracted increasingly attention due to their extraordinary physical and chemical properties.In this paper,drying theory and supercritical drying of wet-gels were simply introduced.And subcritical drying,ambient pressure drying, ambient pressure ladder drying and vacuum freeze drying were reviewed.
The low-carbon olefin such as ethylene and propylene is an important organic chemical raw material and its production technology relates to the development of petrochemical industry. With the development of catalytic pyrolysis, the production technology of low-carbon olefin has been improved. The catalytic pyrolysis of low-carbon olefin technologies were introduced from two aspects, production process and catalyst.
