Experimental Study of Square Inlets Effect on the Performances of Gas–Liquid Cylindrical Cyclone Separators (GLCC)

Use your smartphone to scan this QR code and download this article ABSTRACT In the gas-oil field, the gas-liquid cylindrical cyclone (GLCC) separator has potential replaced the traditional separator that is used over the century. It is also interesting for petroleum companies in recent years because of the effect of the oil world price. However, the behavior of phases in the equipment is very rapid, complex and unsteady which may cause the difficulty of enhancing the performance of the separation phases. The much research demonstrates that the geometry and the number of the inlet is probably the most important factor that impacts directly to the performance of separation of phases of the device. The main goal of the research paper is to deeply understand the effect of different geometrical configurations of the square inlet on hydrodynamics and performances for two phases flow (air-water). Two different inlet configurations are constructed, namely: One square inlet with the gradually reduced nozzle and two symmetric square inlets with the gradually reduced nozzle. As a result, the separation efficiency of the device will be higher when using two symmetric inlets and we suggest the application of two symmetric square inlets type that is the same angle of inclination and the area of the nozzle with the unique inlet configuration to improve separation efficiency in GLCC. Such inlet structure leads to lower swirl intensity decay than one inlet configuration. It also creates a more axis symmetric flow at the center line, which would improve the uplift of air bubbles in the performance of GLCC. Besides, this study can be viewed as a padding step to optimizing the operative parameters of GLCC in the further study.

is pushed radially outward and downward toward the 10 liquid exit, while the gas is driven inward and upward 11 toward the gas outlet. The low-cost, low-weight, com-12 pact GLCC separator offers an attractive alternative to 13 the conventional separator which has been popularly 14 used for this task, are large in size, bulky, and costly 15 in purchasing and operating [1][2][3] . 16 The operational envelope of a GLCC is defined by two oping accurate performance predictions arises largely 24 from the variety of complex flow patterns that can oc-25 cur in the GLCC. The flow patterns above the inlet 26 can include bubble, slug, churn, mist, and liquid rib-27 bon. Below the inlet, the flow generally consists of a 28 liquid vortex with a gas-core filament. Although, they 29 have potential applications, complex phenomenon af-30 fecting the separating efficiency have not been studied 31 completely in the past 1-6 . 32 This difficulty in predicting accurate the performance 33 of the GLCC has been the single largest obstruction 34 to the wide use of the GLCC. Even without tried and 35 tested performance predictions, several successful ap-36 plications of GLCC's have been reported 3 . The de-37 velopment of reliable performance-prediction tools 38 will improve GLCC's through hardware modifications 39 and, ultimately, will govern the speed and extent to 40 which GLCC technology is deployed in existing and 41 new field applications. Recent laboratory observa-42 tions and computer simulations indicate that hard-43 ware modifications to the GLCC can have a profound 44 effect on GLCC performance 2 . The GLCC perfor-45 mance is dependent upon the tangential velocities of 46     Figure 7). But, there is a really 176 interesting which is the oscillation around the tube is 177 relatively uniform when using the two inlet type com-178 pared to the other inlet. This will affect the perfor-179 mance of the separator.

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In the GLCC lower part, if the swirl intensity is high 181 enough, the free gas-liquid interface gets carved out 182 and the vortex can be observed. The liquid flows from 183 the inlet nozzle to the vortex in a thin swirling film 184 (Figure 1), to which we will refer to as Lower Swirling 185 Liquid Film, LSLF. Large bubbles quickly move to-186 ward the free interface due to buoyancy. Smaller bub-187 bles, while being dragged downward by the liquid, are 188 pushed radially toward the vortex center. They form 189 a bubbly filament which allows a nice visualization of 190 the vortex core. These bubbles are supposed to rise up 191 to the free interface and to disengage 1,14 .

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A variety of experiments has been conducted with the 193 both of the inlets to investigate the different flow pat-194 terns in the lower part of the GLCC. The study was re-195 stricted to gas-liquid flow rates upper the LCO limit. 196 The top part of the vortex, the crown, was maintained 197 about 100 mm below the inlet nozzle through a valve 198 installed on the GLCC lower outlet (Figure 8). The 199 vortex level was not set closer to the entrance level for 200 two reasons. The first reason is that in field condi-201 tions, gas and liquid flow rates fluctuate in time. Thus, 202 the vortex level in the GLCC must be maintained at 203 a certain distance from the inlet, so that the control 204 system has enough time to react in the case of a sud-205 den increase of the liquid flow rate, and prevents the 206 vortex to exceed the inlet level and to lead to a preco-207 cious LCO. The second reason is that when the vortex 208 level is too close to the entrance, we observed that the 209 flow gets disrupted. As noticed by Shoham and Kouba 210 (1998) 2 , some distance from the entrance is necessary 211 to achieve an optimal swirl intensity 14 .  is higher than the one for the single inlet ( Figure 12). The operational envelopes for the liquid carry-over 260 (LCO) of single inlet occur earlier than the one of the 261 two symmetric inlet configuration. Besides, when us-262 ing this double inlet type is the working range is also 263 significantly increased.

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The separation efficiency of the device will be higher 265 when using two symmetric inlets. However, the man-266 ufacturing is more difficult and takes up more space 267 than the other. In addition, the two-phase flow bal-268 ance for the two inlets should also be considered.

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Finally, we suggest the application of two symmetric 270 inlets type that is the same angle of inclination and the 271 area of the nozzle with the unique inlet configuration 272 to improve separation efficiency in GLCC. Such in-273 let structure leads to lower swirl intensity decay than 274 one inlet configuration. Besides, it also creates a more 275 axis symmetric flow at the center line, which would 276 improve the uplift of air bubbles in the performance 277 of GLCC.