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Flow dynamics study of catalyst powder in catalytic cracking unit for troubleshooting

Yelgaonkar V., Agrahari G., Vikrant D., Prasanna R., Pathak B. K.

Nukleonika

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2017

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Vol. 62, No. 4

277--283

EN

Gamma scanning and radiotracer applications are very effective and inexpensive tools to understand and optimize the process as well as troubleshoot the various types of problems in many chemical, petrochemical industries and refineries. These techniques are non-invasive; hence, the problems can be pinpointed online, which leads to reduce the downtime, schedule the shutdown and maintenance of the plant equipment, rendering huge economic benefits. In a leading refinery of India, the catalytic cracking unit (CCU) was malfunctioning. It was suspected by the refinery engineers that the catalyst powder was being carried over to the fractionator, which could have led to erosion of the fractionator column internals resulting in their rupture, and consequentially, to the fire hazard. To understand the flow behaviour of the catalyst powder and to ensure the mechanical integrity, catalyst accumulation and choking, both radiotracer study and gamma scanning of the CCU reactor was carried out. The reactor consists of a riser, three primary cyclones and three secondary cyclones. Gamma scanning of the reactor was carried out with the help of an automatic gamma scanner using 1.8 GBq of Co-60 sealed source. Results showed that the catalyst powder was accumulated in one of the secondary cyclones and uneven density distribution was observed in another secondary cyclone. The radiotracer study was carried out using the irradiated catalyst powder as a radiotracer, which contains 0.9 GBq of Na-24. The radiotracer was injected in the reactor through the specially fabricated injection system. Radiation measurement was done using the thermally insulated and collimated NaI(Tl) scintillation detectors located at various strategic locations coupled to a multi-detector data acquisition system. The data were mathematically analysed. It was confirmed that the catalyst powder was accumulated in one of the secondary cyclones with no flow downwards. This resulted in excess powder available to travel along with hydrocarbon towards fractionator. Since the quantity of powder released through the hydrocarbon outlet of CCU was higher than the designed value, the catalyst powder was observed in various zones of the fractionator. Mathematical modelling of the radiotracer data obtained at various locations corroborated the scanning results; also, the flow pattern was obtained. Partially blocked secondary cyclone showed plug flow with recirculation; normal working cyclone had plug flow behaviour and the vortex breaker showed parallel flow.

2

Transversal pressure effect in circulative separators

Sawicki J. M.

Archives of Hydro-Engineering and Environmental Mechanics

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2012

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Vol. 59, nr 1-2

3-12

EN

Progressive urban development of the human environment requires new methods of rain water treatment. Recently, there has been a growing interest in the improvement of gravitational suspension separation, and especially in the application of the centrifugal force. This important factor can be induced in two ways; by the circulation of the reservoir containing the fluid (centrifugal separators), or by a tangent supply of this reservoir (circulative separators). In addition to the centrifugal force, another essential transversal force is at work in this case, resulting from the local variability of the pressure. In the literature, this force is derived for centrifuge conditions, but applied also to circulative separators, which is questionable, as in the latter devices velocity and pressure fields are clearly different. The paper is devoted to the determination of the transversal pressure effect in circulative separators. First, a model of tangent and radial velocity profiles is introduced. The radial pressure distribution, calculated on this basis and verified experimentally, leads to the final result, that is, a technical formula describing the force in question.

3

Możliwości modyfikacji konstrukcji cyklonu zwrotnego z wlotem stycznym

Dziubak T.

Biuletyn Wojskowej Akademii Technicznej

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2006

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Vol. 55, nr 2

279-301

PL

Przedstawiono wpływ wymiarów głównych cyklonu zwrotnego z wlotem stycznym na efektywność odpylania. Zaprezentowano przykładowe modyfikacje konstrukcji cyklonów oraz dokonano ich oceny w zakresie zastosowania w filtrze powietrza pojazdu mechanicznego. Przeprowadzono modyfikację konstrukcji cyklonu D-40 filtru powietrza pojazdu terenowego. Dokonano eksperymentalnej oceny wpływu zmian konstrukcyjnych cyklonu na charakterystyki skuteczności odpylania i oporu przepływu. Określono przy pomocy licznika cząstek rozmiar i liczbę ziaren pyłu w powietrzu za cyklonem przed i po wykonaniu jego modyfikacji.

EN

Influence of main dimensions of returnable cyclone with tangent inlet on air purification efficiency is presented. There are given some examples of cyclones construction modifications. The assessment of their applications in cyclones of motor vehicle air filter was carried out. It was made through modification of construction of D-40 air filter cyclone of terrain vehicle. Experimental assessment of influence of cyclone constructional changes on characteristics of purification efficiency and flow drag was done. The size and number of dust particles in after-cyclone air were determined before and after is modifications using particles counter.

4

Stanowisko badawcze cyklonów filtrów powietrza pojazdów eksploatowanych w warunkach dużego zapylenia

Dziubak T.

Eksploatacja i Niezawodność

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2003

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nr 4

31-46

PL

W artykule przedstawiono niekorzystny wpływ parametrów pyłu drogowego na zużycie współpracujących tarciowe elementów silnika. Wykazano, że w krajowych ośrodkach badawczych, skuteczność filtracji filtrów powietrza silników spalinowych pojazdów mechanicznych, określana jest metodą masową. Pokazano metodę oceny jakościowej filtrów powietrza polegającą na pomiarze ilości i rozmiarów ziaren pyłu w powietrzu przed i za filtrem. Przedstawiono problem zastosowania tej metody do badań dwustopniowych filtrów powietrz-a, gdzie pierwszym stopniem jest multicyklon (bateria cyklonów), a drugim przegroda filtracyjna. Dla tych filtrów zaproponowano metodę badań polegającą na pomiarze ilości i rozmiarów ziaren pyłu tylko w powietrzu za filtrem. Przedstawiono stanowisko badawcze pojedynczych cyklonów filtrów powietrza z wykorzystaniem licznika firmy Parnas. Pokazano wyniki badań wstępnych cyklonu przelotowego z wlotem osiowym.

EN

Disadvantageous influence of parameters of road dust on wear of tribologically mating engine elements is presented in the article. One demonstrated that all homeland research centres investigate efficiency of air filters of combustion engines according to gravimetric method. One showed (lie method of quality assessment of air filters, which method is based on measurement of quantity and dimensions of dust grains in the air from input and output of the filter. One described the problem of application of tins method for investigations of two-step air filter comprising multicyclone as the first stage and filter medium as the second stage. For two step fillers one proposed the method, in which one carried out only the measurement of quantity and dimensions of dust grains included in the air of output of the filter. The test stand, comprising particle counter Pumas, to investigate single cyclones of air filters was presented. The results of preliminary investigations of pass cyclone with axial input were shown.