The Experts below are selected from a list of 81 Experts worldwide ranked by ideXlab platform

Octavian Floarea - One of the best experts on this subject based on the ideXlab platform.

Peter J. Heggs - One of the best experts on this subject based on the ideXlab platform.

  • Modelling a Vertical Thermosyphon Reboiler Operating Under Vacuum Using Data from Rigorous Experimental Studies
    Chemical engineering transactions, 2009
    Co-Authors: Abdelmadjid Alane, Thomas L. Rodgers, Peter J. Heggs
    Abstract:

    Thermosyphon Reboilers represent effectively a pumpless system, in which natural, gravity-assisted circulation takes place. Although these units are the most commonly used in the chemical industry, Arneth and Stichlmair (2001), their operation has only been considered within the context of wider experimental programmes with few studies conducted below atmospheric pressure. In addition, previous research carried out to determine the operating characteristics of Thermosyphon Reboilers decoupled the problems related to heat transfer into a tube side and a shell side, usually by means of an electrically heated single tube (uniform heating). Thus, it is of paramount importance to look at the coupled problem to obtain better estimates of the heat transfer coefficients for the condensing steam in the shell and the heated process fluid in the tubes. The work described in the present article is carried out in this context and provides a detailed description of a mathematical model developed to predict the steady-state performance of a vertical Thermosyphon reboiler. A number of operating variables have been predicted. Analysis of these predictions and comparisons with the generated experimental data, reported by Alane and Heggs (2007), resulted in good agreement. The resultant model could be used for optimisation studies on existing Thermosyphon Reboilers and the design of new ones.

  • The Re-commissioned Thermosyphon ReboilerResearch Facility In The Morton Laboratory
    Advanced Computational Methods in Heat Transfer IX, 2006
    Co-Authors: Abdelmadjid Alane, Peter J. Heggs
    Abstract:

    Vapour generation through boiling is one of the most ubiquitous industrial processes. Vertical Thermosyphon Reboilers are frequently used to generate vapour at the base of distillation columns. Present design methods have the major emphasis on the process side (boiling). The heating of the vertical boiler is decoupled from the system. Additionally, most academic research has considered a single tube flow arrangement with controlled and uniform electrical heating. However, many applications in distillation are now using sub-atmospheric pressure operation (higher thermodynamic efficiency, reduced energy consumption, prevents thermal degradation, cheaper materials of construction and safe operation). The literature does not contain many references to this mode of operation and existing design techniques do no adequately cover sub-atmospheric pressure operation. The Thermosyphon reboiler research facility at the University of Manchester in the Morton Laboratory comprises 50 tubes of 3 m thermal lengths (19.86 mm ID) and 3 segmental baffles (TEMA E type shell and TEMA A type header) with steam condensing on the shell side, 2 large horizontal condensers with 106 and 196 tubes, both TEMA E type shells and B type headers. Vacuum is pulled on the process side and the shell side by means of two separate liquid ring pumps. The process fluid is water flowing in the tubes counter-current to the condensing steam in the shell side. The primary objective is to study the operation of the Thermosyphon reboiler over the pressure range 0.1 bar – atmospheric. New additional instrumentation for temperature, pressure and flow measurements have been calibrated and installed. At the present time, the equipment is fully instrumented, re-insulated and has been successfully commissioned. This paper describes the equipment in detail, its configuration, instrumentation (control, safety and scientific), modifications from the previous arrangement (Emerson DeltaV computer control software and data logger, new instrumentation) and the effect on errors in the mass and energy calculations. A brief reference will be made to the complications encountered during commissioning and the solutions adopted.

Ioan Parjol - One of the best experts on this subject based on the ideXlab platform.

Mehdi Tahmasbi - One of the best experts on this subject based on the ideXlab platform.

  • application of heat transfer enhancement on vertical Thermosyphon Reboilers using tube inserts
    Heat Transfer Engineering, 2006
    Co-Authors: Mohamad Reza Jafari Nasr, Mehdi Tahmasbi
    Abstract:

    Vertical Thermosyphon Reboilers and evaporators are widely used in the process industries. However, increasing the thermal efficiency of these units is very difficult. They are commonly used for about 70% of all evaporation duties in chemical industries. The flow in these units depends on the amount of buoyancy created by vaporization. The flow rate is therefore related not only to heat transfer rate, but also to evaporation, friction, and static pressure loss. The hydrostatic heat present at the base of a vertical Thermosyphon reboiler suppresses boiling, creating a sub-cooled region. At the base of the tube bundle, this region length sometimes approaches a significant percent of tube length. Because single-phase convective heat transfer is the dominant heat transfer mechanism in this region, tube inserts can be used to promote heat transfer without blocking flow. In this article, using a simulation model that has been validated against the result of HTFS software, the effect of using different types of ...

A. W. Sloley - One of the best experts on this subject based on the ideXlab platform.

  • Properly design Thermosyphon Reboilers
    Chemical Engineering Progress, 1997
    Co-Authors: A. W. Sloley
    Abstract:

    Thermosyphon tower Reboilers can be the most reliable means of heat input into a distillation, stripping, or absorption tower. They have no moving parts requiring maintenance or mechanical seals that leak. Properly designed, they can be used across a wide range of process conditions. However, application experience with them has led many plants, and occasionally entire industries, to avoid using Thermosyphons. This is unfortunate, since often a low-cost alternative for a reboiler may be unjustly eliminated. This article covers some of the major design and operating requirements for Thermosyphon reboiler systems. For example, the nature of the pressure balance loop and the interaction between fluid flow and heat transfer make designing Thermosyphons more difficult. The engineer must pay attention to more details and understand both the static design of the system and the potential dynamic behaviors.

  • Effectively design and simulate Thermosyphon reboiler systems: Part 2
    Hydrocarbon Processing, 1995
    Co-Authors: G.r. Martin, A. W. Sloley
    Abstract:

    Thermosyphon Reboilers provide a simple, low-maintenance design for distillation tower reboiler systems. With an understanding of all the factors involved, Thermosyphon designs should be more reliable than most other reboiler systems due to an absence of moving parts (pumps) in the process circulation loop. Design of true Thermosyphon exchangers requires an intimate knowledge of a distillation tower`s heat balance, temperature levels and pressure balance in the reboiler loop. Temperature levels vary strongly with composition gradients depending on the system`s relative volatilities. Case studies of two industrial units demonstrate implications on exchanger design of the correct and incorrect simulation configuration. The two cases compare a low relative-volatility ({alpha}) system (ethylene-ethane splitter) and a high {alpha} system (FCCU deethanizer). Part 1 covered basic Thermosyphon design, advantages and disadvantages. Also, simulation requirements, {alpha} impacts and one-heat-source configurations were discussed. Part 2 continues with configurations of two heat sources at the same and difference temperatures. In addition, comparisons are made between the different designs to show an optimum for each case.