Field Measurement Analysis And Numerical Simulation Of Heat Moisture Environment In Paper Industrial Plants Under High Temperature And Humidity Environment

In recent years, with the development of modern paper industry, the scale of Papermaking plant is becoming larger and larger. Because of a great deal of heat and wet generated in the papermaking process, it's becoming urgent to solve the problems of ventilation and wall condensation in Papermaking plant. Although Numerical simulation has been widely used in research, field measurement is also necessary and superior to any simulation, because the measured data while actual operation process reflect the actual situation,actual problems in ventilation system will be proposed easily,and a series of datas will be accumulated to verify and improve the numerical simulation. In this paper,both Numerical simulatio and Field measurement are used to research the distribution of temperature and humidity.In this paper,test points,methods and instruments are introduced briefly.Then,the test results of temperature and humidity in the papermaking plant are analyzed systematically to get the temperature distribution below the hight of 6m in wet and drying department of papermaking pant.Finally,The distribution characteristic of moisture content and ralative humidity is summerized.Based on the measured data such as heat flux of envelopes,temperature,humidity and volume of air supply and air exhaust,and equipment parameters ,heat dissipation and wet bulk volume of equipments are calculated,which will provide accurate boundary conditions and verifying data for numerical simulation.During the simulation with FLUENT commercial CFD software ,the model of heat and moisture source in papermaking plant will be simplified, as much as possible to actual situation, considering the scattered heat source and wet source. Improtantly, boundary conditions of Papermaking plant is the key to the simulation. In this paper, Yueyang Paper Industry plant will be devided into five parts of wet end, front drying department, glue department, back drying department and completing department,and the plant is simulated with each heat source and moisture source calculated based on measured data.According to the characteristics of papermaking workshop, a standard k-εmodel is used together with the algebraic equation of eddy viscosity directly in the near-wall region. The difference scheme is power law scheme. Boussinesq approximation and SIMPLE algorithm is adopted while control equations are solved on non-uniform staggered grid. In this way, the simulation results in winter are obtained, such as temperature, relative humidity and water content. In this paper, based on the Fitting formula of water content,dew point distribution of envelope with different air supply are analyzed,especially the most probable condensatin area.Also,with the comparision of different simulated cases,the best case is chosen.According to the results of simulation, we draw a conclution that the dew point temperature of envelope in wet end is the highest, and it is positive to strengthen air distribution and insulation measures and to reduce the number of windows for preventing wall condensation here. At the same time,compared with the exhaust ventilation only on the roof, the local exhaust ventilation on the side wall is easier to carry-off the heat and moisture, especially the local exhaust ventilation on the side wall near the backside of operation end.