| The flow rate distribution of liquid in trickle-bed reactor (TBR) is studied in this thesis. The mainly objective includes two parts: One is to develop the mathematical m odel t o study t he flow m echanism o f 1 iquid i n t he b ed of TBR, and the other is to study the technology and device to distribute the liquid uniformly.In the first part, some theoretical models were established to simulate the distribution of flow rate of liquid, such as discrete model, differential calculus model and stochastic model. But these models are difficult to calculate or can't lead to good results. With the guidance of Prof. Li, the author studied the distribution of flow rate in TBR using homogeneous equation of Markov. The results shown that, the calculated and experiment data coincide well with each other.In the later part, the author develops a set of gas-liquid modulating device to regulate the flow rate distribution of liquid. The following are the details of the two parts.The flow rate distribution of liquid in TBR is studied under the conditions 1. of common temperature and standard atmospheric pressure. The random mathematical model is described using equivalent Markov equations. The time and state parameters are discrete. Based on the model, the flow rate distributions along radial and average at any height can be calculated directly, Moreover, the probability transition matrix of the flow can be determined via the statistic character of the random cumulateparticles, and be corrected by S. CD The random theoretical modelShown in fig.l, the section of the bed of TBR is divided into a seriesof concentric circles.The radius of the circles are labeled as from r1 to rn (rn is just equal to the radius of TBR), and these circles divided the TBR into different flow fields. The flow fields are marked from 1 to N separately, and the wall of the reactor is the flow field of No. (N+1). Supposed that the fluid in all the fields will accomplish a transport in down-flow distance A Z, the flow in trickle-bed is a M step Markov process, where M=Z/ Z (Z- the height of trickle-bed).According to the theory of random process, the statistic of the Markov process will be calculated out from the original distribution and state-transport matrix. Now, the probability transport matrix IP is established with PIJ as element, where Pij is the probability of successful transport of the fluid from field (i) to field (j) in one step:If the original distribution of flow rate is F[F1(0) ,F2(0) FN+1 (0) ],namely,Where Lj(0) is the original flux of the corresponding field and L is the total flux across the trickle-bed, the distribution of the flux after one step of transport will beSo the distribution of flux after m steps of transport will beIn the following matrix, a correction factor S is introduced to correct the influence of various factors, such as the traction of gas and the shapes of filling in TBR, on the distribution of flux. Then the triangular diagonally matrix IP can be deduced as followed:The parameters S and fare calculated using the following aim function:(2) The theoretic deduction of the radial distribution of fluxThe author improves the distribution of liquid flux by using gas-liquid modulating device, which are made of a group of short homocentric tapers. Based on the structure and function of the gas-liquid modulating device, the liquid can't diffuse outward but cumulate into the first layer of inside when it arrived the device. So P(1,1)=1, P(i, i+1)=0, P(i, i)=0, P(i+1,i)=1, then the transition matrix of the first layer is:2. Based on the intrinsic character of the liquid flux distribution in TRB, a group of short homocentric tapers with holes are used as gas-liquid modulating device. The experiment results shown that, the liquid flux distribution in the improved TBR is more uniform than that in traditionalTBR, and the wall flux decrease clearly.The experiment system is air-water, the katalyst grain is squeezed strip. The structure parameters of...
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