CAD System Developed By VLISP And VBA On Tube Arranging For Tube-sheet Exchangers

This paper introduces the auto-arranging of heat tubes for tube-sheet heat-exchangers,the most common pressure vessels used in chemical industry. The emphasis of this paper is put on the research and development of automatic parameterized layout of this kind of heat-exchangers,based on the structural and functional analysis done by us. Therefore,the thesis involves our basic design concept,model design,basic algorithm,programming skills and interface design. The completion of the following tasks leads to our final CAD system:1. Automatic arrangement of four standard patterns of pipelines (30?760?745 ?790 ?) and eight different flow orders, in accordance to two different design conditions:the total number of heat tubes or the inner diameter of the shell;2. The development of basic functional models for computing, designing,editing and intercommunicating, such as the layout algorithm, the design and placement of dead block,and adding and deleting of heat tubes.3. Automatic computation and modification of the dimension, the number of total heat tubes and rows, the body line of layout areas and other results involved.4. The programming of various functional models and their communication,coded with Visual LISP and VBA and based on the opening structure of AutoCAD and its entity database.According to the basic requirements of "The Regulation on the Design of Tube-sheet Heat-exchangers",this CAD system has been developed,which can produce the ideal layout the users need,shorten the designing period and better the designing quality.