Badak LNG plant utilizes Multi Component Refrigerant (MCR) as cooling medium for natural gas liquefaction. In the process system, a heat exchanger is serving as compressor aftercooler that cools down this MCR (gas with mostly Methane and Ethane) by means of sea cooling water. This particular heat exchanger is constructed with Rod-Baffle design with Titanium tubes. The design also incorporates a vapour belt at shell inlet/outlet that is functioned as flow distributor.Badak LNG has 8 plants called process trains; with each process train has one MCR aftercooler. The aftercooler at each train has difference in terms of vapour belt design.During plant operations, vibration problem has repetitively occurred in all MCR aftercooler and caused tube leaks. However, a computational fluid dynamics study revealed that the fluid velocity was low enough to generate tube vibrations. However, Rod-Baffle design uses single support direction per baffle. With 4 axis of support (X+, X-, Y+, Y-), one direction support will repeat at the 5th support, 10th support, and so on.Calculation was then made to confirm the effect if one of the baffle failed to support. This condition will increase the length between baffle by 2 times. Consequently, the fluid critical velocity will decrease by 4 times.This approach was then compared with the fluid velocity pattern inside the exchanger shell. It concludes that the fluid velocity is above its critical velocity. Thus, the exchanger is vulnerable to vibrations.Each MCR aftercooler has different vulnerability to vibrations due to vapour belt different designs. The study has concluded the comparison of vulnerability of the exchangers. Exchanger A has 25.9 % tubes having tubes vulnerable to vibrations, while Exchanger F (with different vapour belt design) has only 1.92 % tubes vulnerable to vibrations. With 2000 tubes quantity, the effect to process conditions is significantly different between exchangers.This paper concludes that design of vapour belt can significantly improve the reliability of Rod-Baffle type heat exchanger.Copyright © 2014 by ASME

Vibration Vulnerability of Rod Baffle Type Heat Exchanger: Case Study Badak LNG MCR Aftercooler

A review of corrosion failures in shell and tube heat exchangers: roots and advanced counteractive

Shell and Tube Heat Exchangers are one of the most popular types of exchanger in heat transfer applications. Due to the flexibility, the designer has to allow for a wide range of pressures and temperatures. They are widely used in petroleum refineries, chemical plants, petrochemical plants, natural gas processing, air-conditioning, refrigeration and automotive applications. It utilizes a bundle of tubes through which one of the fluids flows. These tubes are enclosed in a shell with provisions for the other fluid to flow through the spaces between the tubes. In most designs of this type, the free fluid flows roughly perpendicular to the tubes containing the other fluid, in what is known as a cross-flow exchange. In nuclear reactors fuel rods may replace the tubes, and the cooling fluid flowing around the rods removes the heat generated by the fission process.A comprehensive Finite Element Analysis (FEA) has been performed on the critical heat exchanger components in order to validate the results of the components designed using the prescribed codes. The computational analysis helps visualize the areas of high stress concentration thereby aiding the designer to identify the failure prone regions. The regions susceptible to failure can be suitably modified to safeguard against failure. This paper aims at performing a design outputs by IBR codes of critical components of a shell and tube type heat exchanger in an attempt to show the redundancy in designing the components. Furthermore FEA shown the values of stress getting developed in the components for given operating conditions are much lesser than the allowable values of stress for those respective material. Thus the components are safe against such loading.

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Numerical Investigation of Internal Pressure in a shell and Tube type of Heat Exchanger by using FEA

---------------------------------------------------------------------------------------------------------Heat exchangers are devices used to transfer heat between two or more fluid streams at different temperatures. A very serious problem in the mechanical design of heat exchangers is flow induced vibration of the tubes. There are several possible consequences of tube vibration, all of them bad. The tubes may vibrate against the baffles, which can eventually cut holes in the tubes. In extreme cases, the tubes can strike adjacent tubes, literally knocking holes in each other. The repeated stressing of the tube near a rigid support such as a tube sheet can result in fatigue cracking of a tube, loosening of the tube joint, and accelerated corrosion. The flow induced vibrational analysis is considered as integral part of mechanical and thermal design of shell and tube heat exchangers. TEMA has developed standards in areas of flow induced vibrational analysis which have achieved worldwide acceptance. The paper explains depth vibrational analysis of a real world project in accordance to TEMA regulations.

Vibrational Analysis of a Shell and Tube Type of Heat Exchanger In Accordance With Tubular Exchanger Manufacturer's Association (Tema) Norms

The shell and tube type heat exchanger is a non-fired pressure system consisting of two different pressure chambers such as shell chamber and tube chamber. It is separated by the internal tube wall, two media flow past each other with such alignment that, if there is a heat difference, they will mutually exchange heat without mixing in the process..While there is an enormous variety of specific design features that can be used in shell and tube exchangers, the number of basic components is relatively small. This paper aims at performing a comprehensive comparison of the design outputs by IBR and ASME codes of critical components of a shell and tube type heat exchanger in an attempt to show the redundancy in designing the components using both these codes simultaneously.

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K. N. Dhumke

Papers

Vibrational Analysis of a Shell and Tube Type of Heat Exchanger In Accordance With Tubular Exchanger Manufacturer's Association (Tema) Norms

Determination of Internal Pressure in a Shell and Tube Type of Heat Exchanger by Using IBR and ASME Codes

Numerical Investigation of Internal Pressure in a shell and Tube type of Heat Exchanger by using FEA