Application of numerical simulation in the design of wire-mesh mist eliminator
Previous design of wire-mesh mist eliminator relies on enormous experiments and consumes a lot. In this paper, its pressure drop is simulated by numerical simulation, and non-simplified three-dimensional calculation model is established. After calculated under the flow velocity of 3-10m/s and compared it with the experimental data, the results show that the numerical simulation result achieves a very high precision. Meanwhile, the influence of different wire diameter and space between wire-mesh layers on the pressure drop of mist eliminators is studied and the proper space between wire-mesh layers within the scope of wire-diameter is 0.6mm–0.8mm. Two types of model were verified through the model experiment and the experimental error is less than 4%, which can be a theoretical guidance for designing mesh filter.
Conventional and Complex Knitted Mesh Mist Eliminators
Knitted wire mesh mist eliminators have a widespread application in many industrial plants as they assure an optimum cost/performance for many applications compared with other separation devices. Complex mesh pads allow the performance and the range of applications of conventional wire mesh pads to be extended. In recent years, increasing research effort has been dedicated to the experimental investigation of both common and complex mesh pads and to the development of reliable design models that are essential for the design and optimization of complex separation units.
Solving equations simulating the steady-state behavior of the multi-stage flash desalination process
The paper presents an algorithm for solving the equations simulating the steady-state behavior of the multi-stage flash (MSF) desalination process. The model can be used either for designing new plants or anlysis and optimization of existing units. The set of equations relating the large number of design and operating variables for any stage (i-th stage) in MSF plants is broken down into three subsets. The first subset contains equations describing processes in the tubes of the preheater inside the flashing chamber. The second subset deals with the processes inside the flashing chamber. These two subsets of equations are subsequently solved iteratively involving only a single variable for each subset. These variables are: (1) saturation temperature Tvi of the flashed-off vapor and (2) temperature of the unevaporated brine flowing from the chamber. The third subset of equations considers the existing interactions between the first two subsets. This subset defines the mass of vapor formed by flashing Di in the i-th stage. All equations in the above-mentioned subsets are solved by a reliable and efficient one-dimensional fixed-point iteration. The main advantages of this method are less sensitivity to initial guesses, fewer iterations to obtain the required solution, and no need for calculating derivatives. The algorithm is implemented using the computer-aided design (CAD) interative package L-A-S (Linear Algebra and Systems). Detailed results are presented to show the dependence of the important factors controlling the fresh water cost, which are plant performance ratio, specific heat transfer area, specific brine flow rate, and specific cooling water flow rate, on the most significant two design variables, namely the total number of stages and the top brine temperature. The predicted data from the model are compared with published data of a typical MSF plant in operation at Kuwait. The agreement was found to be very good.