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The design of falling film evaporators

Kok, K.R. (2014) The design of falling film evaporators.

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Abstract:Huntsman Polyurethanes Rotterdam uses tube falling film evaporators in their processes. This type of evaporators is a proven concept and has been used in various chemical plants in the past 50 years. Huntsman wanted to know if there is a alternative for these evaporators available. They received the message that their evaporators might be outdated and they would like to improve their production sites with better equipment. The report will start with an introduction of the MDI plant in the Port of Rotterdam. An brief overview of the different plants and processes at the production site will be given. The subject of the internship is mainly focused on the Keystone part of the MDI2 plant. This part is analyzed to get the operation conditions for the falling film evaporators. The Keystone part of the plant is operating for half a year and it operates very well. Some adjustments has been done on the initial design to improve the system. The falling film evaporators operate very stable and according to their design. The flow inside the falling film evaporators is analyzed to get more understanding in the working principles. The two phase inside the evaporators is quite complex and requires a numerical solution which is checked with a physical model. This was not possible during the internship, but the analysis with simple empirical equations gave good results. The empirical relations approximate the operating conditions with an accuracy of 5%. The report will discuss some of the working principles of the current tube evaporators. The evaporator is designed with some special features such a specific pipe diameter and inserts. In the last part of the report the alternatives for the current evaporator will be discussed. The chosen concept is a vertical plate falling film evaporator. This evaporator has some advantages over the current evaporator. The weight of the evaporator can be reduced with 30% and pressure drop in the MDI ow will be lower. The working principles of the new evaporator will also be explained in this section. The report concludes with the conclusions that the current evaporators operate good, the given equations approximate the operation conditions well and the plate evaporator could be an interesting option for the replacement of current evaporators. It is recommended to look at the option for plate evaporators for a replacement or a new plant. If desired a numerical model could be made for better understanding of the flow inside the evaporators. The process data, such as throughputs, split ratios, chemical properties and detailed equipment descriptions, of the plant is confidential information. All the confidential data is removed from the report. The confidential report is only available for employees of Huntsman.
Item Type:Internship Report (Master)
Clients:
Huntsman, the Netherlands
Faculty:ET: Engineering Technology
Subject:52 mechanical engineering
Programme:Mechanical Engineering MSc (60439)
Keywords:Huntsman, Evaporators, Falling film, MDI Process, Process analysis
Link to this item:http://purl.utwente.nl/essays/69344
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