TiN和TiC涂层对碳氢燃料裂解结焦的影响

采用化学气相沉积(CVD)法,在304型不锈钢管道内壁分别沉积了TiN和TiC涂层,并采用SEM、EDS、金相显微镜和热冲击等方法对其进行了性能表征和测试。结果表明,两种涂层均匀致密,TiN涂层厚度为7.24μm,TiC涂层为11.52μm,且均具有良好的结合强度。为评价涂层抑制结焦效果,选用某碳氢燃料A,采取程序升温法进行超临界裂解实验,当反应管前后压差超过1 MPa时停止实验,结果表明,304空白管由于严重结焦,在650℃只运行了180 s;而TiC和TiN涂层管分别在780℃运行了275和1560 s。通过压差、产气组成和积炭微观形貌的综合分析表明,TiN、TiC涂层均呈现出优良的抑焦效果,且TiN涂层抑焦效果更优。

The anti-coking effect of TiN and TiC coatings during pyrolysis of hydrocarbon fuel

In order to inhibit the metal catalytic coking, the TiN and TiC coatings were made on the inner surface of stainless steel 304 tubes by chemical vapor deposition (CVD) method. The coatings were characterized by means of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), metalloscopy and thermal shock. The results show that the thickness of TiN and TiC coatings is about 7.24 μm and 11.52 μm, respectively. And the two kinds of coatings are uniform and dense, which have a good adhesive strength. To evaluate the anti-coking effect of TiN and TiC coatings, the supercritical cracking of hydrocarbon fuel (A) was employed in the temperature programmed mode and the experiment was terminated when the pressure drop of reaction tube is more than 1 MPa. The results show that the experiment with the 304 blank tube is terminated in 180 s at the reaction temperature of 650 ℃, while the experiments with the TiN and TiC coated tubes are terminated in 275 s and 1 560 s only at 780 ℃, respectively. At the same time, the anti-coking effect of the coatings is evaluated by analyzing the pressure drop, gas composition and morphology of coke. It is indicated that the two kinds of coatings could inhibit coking effectively, and TiN is better than TiC.