Development design of an acoustic cleaning apparatus for boilers at Sasol synfuels power station plant in Secunda

P. M. Shandu, D. V.V. Kallon, L. K. Tartibu, R. Mutyavavire

Research output: Contribution to conferencePaperpeer-review

6 Citations (Scopus)

Abstract

This paper assesses the maintenance techniques employed to clean coal fired boilers used for power generation at SASOL Synfuels Power Station based in Secunda, in South Africa. Adequate maintenance of boilers used in power plants can result in improved efficiency of the boilers and this ultimately reduces operating cost of the power generation plant over the long term. This research investigates the parameters required for the design and installation of an acoustic apparatus for the online cleaning of these boilers as well as the design of a beam that can withstand the induced vibration from the horn. The sound energy from a sonic horn is converted to vibrations along the boiler tubes thereby dislodging soot. Using AutoCAD Invertor 2016, parts of the acoustic horn were modelled and simulated against predicted forces and pressures and then compared with the calculated results. Using the simulation on AutoCAD 2016, it was determined that the diaphragm will deflect by 0.5 mm under the action of a 552 kPa pressure. It was also further found that the stress what will be acting on it will be 816 MPa only if the diaphragm does not deflect and bleed out the air hence the stresses will not reach their expected maximum. The acoustic horn chamber only experiences a pressure of 50 MPa which is acceptable. The acoustic cleaning solution is a combination of a horn and a beam. The design of a beam that will withstand the force given off by the horn is discussed in this paper. The natural frequency of the beams was found to be 70.67 Hz which falls correctly into the real-life limitation of (60 – 75 Hz). This frequency range is the most powerful and sufficient for cleaning silos and large vessels. A force matching this frequency was found to be 225 N which is also the fracture load and the maximum deflection caused by this force and frequency was found to be 26.2866 mm. Thus there is a range of deflections for which the beam vibrates at close to its natural frequency. In theory the material selected was found to be significant (cast iron) and can reach a maximum deflection of 26.8866mm and a max stress of 182.655Mpa at a force of 820N. In practice, however, this is not recommend as the beam will not have a long life span therefore one should rather work at a force ranges of 220N to 300N as this is the force at which the beam can remove enough soot without undergoing serious damaged. The testing of the device shows enhanced cleaning at low risk of corrosion and erosion to the surrounding structures especially boiler tubes. The resulting improvement on the boiler performance is noted. Acoustic cleaning technique therefore can improve maintenance of boilers which in turn improves the boiler’s efficiency while reducing outages.

Original languageEnglish
Pages900-909
Number of pages10
Publication statusPublished - 2018
Event11th South African Conference on Computational and Applied Mechanics, SACAM 2018 - Vanderbijlpark, South Africa
Duration: 17 Sept 201819 Sept 2018

Conference

Conference11th South African Conference on Computational and Applied Mechanics, SACAM 2018
Country/TerritorySouth Africa
CityVanderbijlpark
Period17/09/1819/09/18

Keywords

  • Acoustics
  • Boilers
  • Design

ASJC Scopus subject areas

  • Mechanical Engineering
  • Computational Mechanics

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