Tag: Instrumentation

Dr M. Olbricht and Dr J. Weidenfeller of Schmidtsche Schack | ARVOS (SCS) discuss the impact of the heat recovery equipment arrangement in an ammonia plant downstream of the secondary reformer on reliable boiler operation. A detailed investigation was performed by SCS in response to an operator experiencing difficulties in maintaining water quality in this critical equipment. Water quality has a crucial impact on the lifetime and reliability of the equipment.

With the ongoing changes in gas field and refinery feedstock compositions, many sulphur recovery units around the world are facing turndown scenarios to such an extent that it is difficult to meet stringent environmental regulations. Equipment and instrumentation behave differently under turndown conditions, and not always in ways that are desirable. Start-ups and shutdowns can place demands on the equipment that are more severe than years of normal operation. In this article, Optimized Gas Treating, Sulfur Recovery Engineering and Comprimo share some of their learnings and experiences of these scenarios.

A Stamicarbon urea plant attempts to start up after a scheduled turnaround. Due to maintenance issues, it is necessary to shut down and block in the synthesis section several times. Although licensor’s procedures have been followed, several signs of active corrosion are noticed in the liner of the reactor. What could the cause be for this unexpected behaviour? Can sharing experiences from colleagues from other urea plants provide valuable support to find the root cause or even provide new insights into possible new causes? One observation is that the typical heating up rate of a liner in a reactor is much higher than recommended (refer to diagram). The condensation heat of steam heats up the liner much faster than the carbon steel pressure bearing wall. This creates stress on the liner and affects the lifetime of the liner. Another observation is a temperature rise in the reactor during a blocking in situation. This can be a cause for loss of oxygen required for passivation, resulting in higher corrosion rates.

As existing facilities grow older, service requirements increase. Equipment needs to be low maintenance and back in operation quickly after service and repair. Technology licensors are expanding their technical services with new digital tools, using digitalised expertise with real time insights and data driven analytics to boost chemical production and ensure that equipment operates reliably and efficiently, while maintaining product quality.

Applied Analytics discusses potential improvements made possible with data and analytical measurements fed into improved mathematical models to produce a more proactive approach to control and better performance of sulphur recovery units, AMETEK Process Instruments explains the benefits of feed forward control, SICK reports on reliable continuous emission monitoring systems and WIKA introduces a new purge-free system to measure refractory temperature in the Claus reaction furnace.