Article ID : 277 |
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PUBLISH DATE: Tuesday, May 8, 2018 |
PUBLISHTIME: 12:00 AM |
Azar Energy Centrifugal trays
The forces due to gravity are quite insignificant in mass transfer operation. Forces which are more than five orders of magnitude larger can be obtained in centrifugal devices (Krishna, Multi component mass transfer, Mc Grew Hill, 1992)
The centrifugal trays developed by Azar Energy Co. have been recommended as high efficiency contact devices. Due to features of our design, they are much better than all existing analogs with respect to unit loads in vapor and liquid. The optimum area of application is for mass exchange under pressure.
The higher the gas velocity, the greater the centrifugal force and the better the separation of the liquid. Entrainment of the liquid decreases with an increased in the gas velocity, so that the maximum acceptable loads for a centrifugal tray are not determined by entrainment of the liquid but by the acceptable pressure drop. The throughput for gas and liquid phases simultaneously increases in the centrifugal tray. Studies on experimental and industrial tests of centrifugal trays confirmed this conclusion.
Centrifugal trays are especially efficient at high liquid loads or very high vapor flows in towers under pressure. Then, the centrifugal trays significantly reduce the tower size or significantly increase its throughput.
In additional to high throughput, it is necessary to note another feature of the centrifugal trays - efficiency of separation of strongly foaming liquid, including aqueous solutions of amines: MEA (monoethanolamin), DEA(diethanolamin), or mixture of them.
The experimental studies of operation of centrifugal trays on foaming liquids showed that because of intensive reaction of the gas with the liquid, the foam is broken down at high gas velocities. As a result, the throughput of centrifugal trays is much higher than for bubble trays.
Centrifugal Trays : type A
The centrifugal tray fixed or push valves change the path of ascending vapor from vertical to horizontal and this lead to higher pressure drop in dry tray. Higher dry pressure drop at low gas rate cause lower weeping from holes. Therefore as the graphs shows the centrifugal tray has no or a little weeping at low gas rate and better turn down ratio with respect to other conventional trays such as sieve trays.
But the interesting matter in these vapor liquid contacting devices is vice versa action of them for wet tray pressure drop. By increasing the flow rates tray geometry intensifies the effect of wake phenomena on each push valve on the tray deck. This gas suction behavior is responsible for lower wet tray pressure drop rather than other type of trays.
The rotating path of gas and liquid flow arises in tray spacing as a result of circulation arrangment of the holes and establish little entrainment rate at high vapor and liquid loads because of falling of a wide rangs of the jumped droplets in the downcomer after rising by the ascending gas force. These trays can operates as high capacity contacting devices and are practical solution for revamping or turn up of tray towers.
The centrifugal trays are good devices for fractionating columns exposed to foaming and fouling problems. In the foaming services such as sweetening of hydrocarbons mixtures by amine solutions the geometry structure of these trays prevents foam formation after amines-hydrocarbon contacts. Formed foam bulks are breaking as soon as starts to increase by these trays.
The experimental data for sieve and centrifugal trays was computed at below figures. These data are governed by pilot A1, A2 and B.
Figure 1- Azar Energy Modified Centrifugal Trays 6 cm Weir- Flow Regime. Azar Energy Research and Development Center, Tabriz. Iran
Pressure drop test in Tower B for centrifugal Trays 12 cm Weir. Azar Energy Research and Development Center, Tabriz. Iran
Pressure drop test result in Tower B for centrifugal Trays 12 cm Weir. Azar Energy Research and Development Center, Tabriz. Iran
The Licenses of these trays are being to Azar Energy Co. and registed as a patent in Iran by No. 37062 at 2006/11/14. In the recent years, the Azar Energy Centrifugal trays have many Industrial experiences in Iranian oil and gas industries for revamping and troubleshooting services.
This part deal with the results of two case studies in Iranian petrochemical plants As typical instances. Good experiences of these trays installation are in the Razi Petrochemical Plant and Tabriz Petrochemical Plant. The reported results of these plants showed increasing in capacity and efficiency and no fouling problems after installation of these new trays.