Protecting stainless steel surfaces using ppm levels of sulfur compounds during ethylene production

世界上年产量超过1亿吨的乙烯是石化行业生产的最大的化工原料之一。在北美，从乙烯中获得的主要产品是广泛使用的聚乙烯，Nova化学公司在加拿大艾伯塔省经营着世界上最大的乙烯和聚乙烯复合体。乙烯是由多种碳氢化合物高温蒸汽裂解产生的，乙烷是首选。不幸的是，焦炭(固体形式的碳)是作为双产品生产的，这降低了生产效率，通过更高的能源消耗增加了生产成本，并不可避免地导致工厂停机以去除焦炭和更换损坏的高温腐蚀的金属基础设施。特别是，不锈钢管道的金属粉尘可能会导致高压气体管道的灾难性故障。业内已知，碳氢化合物原料中各种硫物种的低水平可以随着时间的推移减少结焦和金属粉尘的严重程度，但保护程度高度依赖于硫物种的数量和类型，以及碳氢化合物原料的组成和它在炉膛热区停留的时间长度。通过与NOVA合作，我们将通过执行一系列新的研究来更好地了解这些因素之间的关系，这些研究近似于钢在500-1000oC的不同停留时间的乙烷、蒸汽和硫物种的热区暴露。在加拿大缺乏合格人才的领域培训学生的过程中，这些信息将被用来通过精确选择合适的硫物种和最佳浓度/条件来生成解决方案，从而将焦化和钢铁腐蚀降至最低。这项研究将对加拿大各种依赖于暴露在高温碳氢化合物反应中的金属(如钢铁)的行业产生重大影响，无论是在制定预防措施方面，还是在各种领域的技术培训方面，包括气态碳氢动力学、表面反应、金属腐蚀以及表面和材料表征。

With well over 100 million tonnes produced annually in the world, ethylene is one of the largest chemical feedstocks produced by the petrochemical industry. In North America, a primary product obtained from ethylene is the widely used polyethylene, and NOVA Chemicals Corporation operates the largest ethylene and polyethylene complexes in the world in Alberta, Canada. Ethylene is produced by high temperature steam cracking of a variety of hydrocarbons, with ethane being preferred. Unfortunately, coke (solid forms of carbon) is produced as a bi-product, which decreases production efficiency, increases production costs through higher energy use, and inevitably leads to plant down-time to remove coke and replace high temperature corrosion damaged metal infrastructure. In particular, metal dusting of stainless steel tubing can lead to catastrophic failure of high pressure gas lines. It is known in the industry that low levels of a variety of sulfur species in the hydrocarbon feed can reduce the severity of coke build-up and metal dusting over time, but the level of protection is highly dependent on the amount and type of sulfur species, as well as the composition of the hydrocarbon feed and the length of time it remains in the hot zone of the furnace. In collaboration with NOVA, we will develop a significantly better understanding of the relationship between these factors by performing a series of novel studies that approximates the hot zone exposure of the steel to ethane, steam, and sulfur species with varied residence times at 500-1000oC. In the course of training students in a field where qualified people in Canada are scarce, this information will be used to generate solutions through precise selection of the right sulfur species and optimum concentration/conditions such that coking and steel corrosion is minimized. This research will have significant ramifications in a wide variety of Canadian industries that rely on metals such as steel that are exposed to high temperature hydrocarbon reactions, both in terms of developing preventative measures, as well as technical training in a variety of areas including gaseous hydrocarbon kinetics, surface reactions, metal corrosion and surface and material characterization.