基于循环系统的膏体浓密机底流调控及其数学模型

Regulation and a mathematical model of underflow in paste thickeners based on a circular system design

为了保证浓密机在高料位下不压耙,一般通过增设循环系统使料浆始终处于活化状态,降低耙架运行阻力.然而,目前循环参数对底流的影响规律不明确,造成系统的设计及应用缺乏科学依据,为此开展了循环参数对底流的调控研究.分析循环系统的作用原理,将循环系统作用范围划分为两大区域,揭示循环参数对底流的调控机制,运用微积分原理对区域内的底流体积分数变化进行求解,最终建立浓密机底流调控数学模型.最后,利用该模型对底流循环实验参数进行验证.研究结果表明:开启底流循环后,底流体积分数开始降低并最终趋于稳定,底流体积分数差随着循环流量及循环高度增大而增大,体积分数变化幅度为0.7%~2.2%,稳定所需时间随流量及高度增加而减小.该理论模型完全吻合验证结果函数,为循环系统的设计及运行提供理论依据.

To assure that compression on the rakes of a deep corn thickener does not stop mixing,an additional circular slurry system,which activates slurry all the time,is employed and running resistance is usually decreased. However,there is still uncertainty on how circular parameters affect underflow properties. This means that the design and application of such systems lack support from scientific theories. Hence,it is necessary to create a study on how circular parameters regulate underflow parameters. Analysis of the circular system mechanism shows that its effect can be divided into two parts and the effect of the system on underflow properties is clarified. In addition,the value of underflow concentration in thickeners is solved based on calculus and finally a mathematical model is produced,which simulates the regulation of underflow properties in thickeners. Using the model,the circular parameters of underflow in thickeners are verified. The experiment indicates that the solid concentration of underflow decreases with circular underflow initiation,then tends to stabilize. Also,the volume fraction of underflow increases in the range of 0. 7%-2. 2% with ascending circular flow and height. In addition,the time necessary for the solid concentration to stabilize is reversely affected by underflow flow and height. The regression function obtained from experimental statistics shows excellent performance in the model when designing and analyzing circular systems for thickeners.