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Replacing Radiant Tubes

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  INTRODUCTION This document describes a recent project where our client was replacing the tubes in the radiant coil of a Crude Fired Heater. The heater was originally built in the 1970s, before the modern standards of API 560 and API 530. The material of the original tubes was A312 TP 310 SS material, however, the client required a review of whether there was any benefit in changing the material of the new tubes to be installed. In order to make a valid assessment of changing the coil material, we had to review the current operational performance and duty requirements of the heater. Therefore, we requested the full performance data for the heater over the last 5 years. This would allow us to understand peak duty requirements and the associated temperatures, pressures, flowrates, etc. In addition to the extreme operation conditions, our review of this data would also reveal the intensity or period of sustained operation at any given condition. The table below outlines the maximum duty
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Crude Oil Fired Heaters

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  What is a Crude Heater? A Crude Heater, sometimes called a Crude Furnace, is a Fired Heater  utilised to heat Crude Oil in a refinery. The Crude Oil process fluid is often heated beyond the point of vaporisation, producing a two-phase fluid mixture at the process outlet. The Crude Heater is a critical unit within the refinery as it directly processes the key feetstock from which all subsequent refinery commercial products are derived. Crude Oil Heater Design Crude Heaters are most commonly designed as Cabin Heaters, with horizontal tubes in the radiant section. A major benefit of utilising horizontal tubes is that the crude oil process fluid can be drained from the coil during plant shutdown and allow easier maintenance activities such as cleaning. For larger duty requirements, these Cabin Heater designs may consist of multiple radiant sections and a common convection section, which may also have secondary process streams to heat water or steam. Cabin Heater with Twin Radiant Cell C
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Maximum Tube Temperature

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  The maximum tube temperature is a crucial aspect of the heater performance that must be assessed during both design phase and operation. Alongside the process pressure, the tube temperature has a fundamental role in determining tube material selection, since each material will have prescribed temperature limits that they can withstand. Thankfully, there are reliable calculation methods that can be utilised in order to determine maximum tube temperature, hence the appropriate tube material can be selected. The temperature calculation is more accurate for single phase process fluids (i.e. either 100% liquid flow, or 100% vapour flow), since the respective heat transfer properties can be reliably calculated for each case respectively. For two-phase fluids, the calculation will have a wider degree of accuracy due to the inherent error margin in estimating physical property characteristics in combination with a particular flow regime. API 530 Maximum Tube Temperature Calculation The API 5
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Introduction to Fired Heaters

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What is a Fired Heater? Fired Heaters are responsible for heating process fluids in Oil Refineries and Petrochemical plants, during the refining and manufacturing of chemicals. There are a number of different types of fluids that may requiring heating, such as Crude Oil, Hydrocarbons, Hydrogen, Water and Steam. These process fluids will flow within tubes usually located around the internal inner wall, whilst burners produce large flames in the centre of the chamber. Fired Heaters are sometimes referred to as Furnaces within the Oil & Gas industry, which has often resulted in some confusion. The three main sections of a Fired Heater is as follows: - Radiant Section - Convection Section - Stack What is the Radiant Section? The Radiant Section contains the burners and tubes usually located along the inner walls, with the heated fluid flowing inside. The Radiant Section will be the hottest part of the heater, with temperatures typically between 700 C (1292 F) to 900 C (1620 F). The pri
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Location: United Kingdom
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