ABSTRACT
In order to study the flow and erosion behavior of gas-solid exhaust in the polysilicon reduction furnace, the flow characteristics of exhaust gas and silicon particles were analyzed. The flow model and erosion model of exhaust gas and silicon particles were established based on the gas-solid flow theory and the erosion theory. The erosion and wear behavior of the gas-solid mixture in the flow passage pipeline were studied by numerical simulation. The results show that the wear and erosion from Nos. 1 to 8 regions at the bottom of the ring were caused by silicon particles colliding with high angle. The wear and erosion of 2 regions from Nos. 9 to 10 at the outside of the up azimuth on both sides of loop pipe outlets, 4 regions from Nos. 11 to 14 on the upper and lower wall of single furnace main channel were severely affected wear regions, which is caused by silicon particles with low angle and high velocity. Through comparative analysis, the erosion of upper wall of single furnace main channel is most serious. Increased gas velocity, particle concentration and particle size will exacerbate the erosion and wear rate of the pipeline in polysilicon reduction furnace, but the distribution and development of severe wear zone would not be affected significantly.
ABSTRACT
Objective To evaluate the efficacy of endotracheal tube (ETT) with injecting medicine for continuous airway topical anesthesia in inhibiting responses to an indwelling ETT after operation in the patients undergoing maxillofacial surgery. Methods Sixty patients of both sexes, aged 18-64 yr, weig-hing 45-75 kg, of American Society of Anesthesiologists physical status Ⅰor Ⅱ, scheduled for elective maxillofacial surgery under general anesthesia, were divided to control group ( group C) and ETT with in-jecting medicine for continuous airway topical anesthesia group (group E) by a random number table meth-od, with 30 patents in each group. ETT was indwelled until the patients were admitted to intensive care unit (ICU) after the end of surgery, midazolam 0. 02-0. 03 mg∕kg was intravenously injected, and sufentanil was intravenously infused at a rate of 0. 02-0. 10 μg·kg-1·h-1for sedation. In group E, 2% lidocaine 2 ml was injected through the ETT with injecting medicine every 2 h to perform airway topical anesthesia. The equal volume of normal saline was injected through the ETT with injecting medicine every 2 h to maintain the Ramsay sedation score ≥2 in group C. The occurrence of hypertension, tachycardia and bucking and seda-tive requirements were recorded within 24 h after admission to ICU. The concentrations of norepinephrine and methoxyepinephrine in urine were determined by enzyme-linked immunosorbent assay at 24 h after ad- mission to ICU. Results Compared with group C, the frequency of hypertension, tachycardia and bucking were significantly decreased, the consumption of midazolam and sufentanil was reduced, and the concentra-tions of norepinephrine and methoxyepinephrine in urine were decreased in group E (P＜0. 05). Conclusion ETT with injecting medicine can markedly inhibit responses to an indwelling ETT after operation when used for continuous airway topical anesthesia in the patients undergoing maxillofacial surgery.
