Tag: Materials of Construction

All acid towers eventually require replacement. In this article, K. Sirikan, A. Mahecha-Botero et al of NORAM Engineering and Constructors Ltd discuss two recently executed acid tower replacement projects. The first project involved the replacement of a brick-lined tower by an alloy acid tower for a sulphur burning plant in North America. The second project involved the replacement of a brick-lined acid tower with a NORAM designed brick-lined tower for a smelter off gas acid plant in South America. The impacts of various design considerations on acid tower replacement projects are compared, including in-situ replacement versus a new location; brick-lined versus alloy shell, and selection criteria for mist eliminators.

Failure investigations, equipment design and process upgrade projects for SRUs often overlook the impact of water quality. In this article E. Nasat o of Nasato Consulting and L. Huchler of MarTech Systems explore impacts of higher heat transfer rates, control of boiler and condenser water chemistry, conventional equipment design/configurations and monitoring program designs. SRU operators can improve the effectiveness of their failure investigations by implementing a broader, more holistic approach that assesses equipment design, process conditions, operating protocols and water quality issues.

Several highly corrosion resistant materials are available today for use in handling process fluids encountered in the production of concentrated sulphuric acid. These alloys, properly selected for the operating conditions, provide the benefits of long operating life under harsh operating conditions extending the period of uninterrupted production cycles and lowering the incidence of catastrophic equipment failure. In this article, M. J. Cooke of Weir Minerals discusses materials of construction for pumps, valves and piping used in the production of sulphuric acid.

Many fertilizers plants are looking to reduce the overall maintenance costs of their critical heat exchangers. Barinder J. S. Ghai of Sandvik Materials Technology takes a look at the life cycle costs of tube materials for heat exchangers in ammonia plants.

Although amine solution foaming problems have been studied and reported extensively, direct correlations about the root causes of foaming have not been completely established. This article approaches the problems of foaming from a different perspective, rather than theoretical discussions, the topic is centred exclusively on Amine Experts’ field-related experiences with amine foaming episodes.

Using case studies of a refinery amine unit and a sour water stripper (SWS), U. M. Sridhar of Three Ten Initiative Technologies LLP, N. A. Hatcher and R. H. Weiland of Optimized Gas Treating Inc. demonstrate the capabilities of a mechanistic, chemistry-based, truly predictive model for calculating corrosion rates for various amines and for sour water. At a time when asset integrity is much sought after, the utility of this fully predictive model is to prevent failures before they occur, rationally select materials of construction, enhance plant safety, and mitigate risk.

Ammonium carbamate is very corrosive under the synthesis conditions in a urea plant. The various process licensors have developed different solutions to assure sufficient safety and reliability levels, but what is the best material?

Austenitic stainless steel can be protected against carbamate corrosion in urea plants by adding oxygen in the urea process. This discussion explores the experiences with different amounts of oxygen in the HP stripper in various urea processes.