Font Size: a A A

Basic Numerical Simulation Research Of The Air Field In The Drying Room Of The Low Temperature Closed Cycle Sludge Drying Equipment

Posted on:2021-04-05Degree:MasterType:Thesis
Country:ChinaCandidate:Y C GaoFull Text:PDF
GTID:2381330647964112Subject:Architecture and civil engineering
Abstract/Summary:PDF Full Text Request
At present,the rapid development of our country’s economy has brought more and more challenges to the environment,and the output of sludge is increasing with the improvement of industrialization.In the light of the analysis of the water content of sludge,the traditional mechanical dewatering equipment can only remove the free water in the four types of sludge,and the dewatering efficiency is low.The low-temperature closed-cycle sludge drying equipment,with heat pump drying as the main technical means,can effectively dry the sludge in depth,so as to reduce the impact of the sludge on the environment,increase the disposal methods of the sludge,has been received widespread attention by the community.Therefore,this article will use the method of numerical simulation to do basic research on the drying room wind field of the low-temperature closed-cycle sludge drying equipment from the perspective of air source and material.ICEM software is used to build the model of the equipment drying room,and fluent software is used to simulate the air distribution of the drying room under the current operating conditions.The results show that for the lower side of the third layer mesh belt which is the first to pass through after the air inlet of the drying room is sent out by the forced draft fan,the velocity distribution of the third layer mesh belt shows that the velocity distribution of this surface is large in the middle and small in both sides,and the overall velocity distribution is not consistent.By observing the middle section of the drying room,it is found that the wind speed on the left side of the third mesh belt is large and dense,and the wind speed reaching the second layer me sh belt has obvious attenuation;the wind speed of the first layer mesh belt is supplemented because it is close to the circulating fan and return air outlet.There is a low-speed sparse region between the second and the third layer.In order to improve the airflow organization in the drying room,five factors that affect the airflow organization in the drying room are listed: the direction of the fan,the presence or absence of baffles,the size of the air volume,the number of blades and the angle of the blades.Four levels are considered for each influencing factor,16 working conditions are designed by orthogonal experiments,and the Fluent software is used for simulation calculation.Taking the uneven coefficient,the surface average velocity,and the surface average pressure as three evaluation indicators,the range analysis is carried out.Sort the influencing factors by comparing the size of the range.Using the position-level trend chart,it is determined that the two fans are turning left and right,there is a baffle in the middle of the two fans,each fan has an air volume of 7000m3/h,15 fan blades and the optimal working condition setting of the blade angle of 75°.Compared with the current operating conditions,the optimal working condition has a more obvious improvement in the uniformity of the flow field,and the working environment of the drying room has been greatly improved,achieving the purpose of optimizing the air distribution inside the drying room.By constructing square,circular,triangular and two rectangular material cross-sectional shapes,numerical simulations are carried out on the heating process of several shapes of materials on a two-dimensional level.Taking wood as the simulated material object,when the drying time is set to 80 s,the average surface temperature of the 4*9 rectangular material is the largest.After appropriately reducing and increasing the drying time,it is found that the 4*9 rectangular material takes the least time to reach the same temperature.It is inferred that the columnar mud strip under this cross-sectional shape has the shortest heating process and the best drying degree.The sludge under this size is easy to shape and easy to industrialize.
Keywords/Search Tags:sludge drying, heat pump drying, numerical simulation, airflow organization, material profile shape
PDF Full Text Request
Related items