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weld overlays) are in passive state

ase and thus the efficiency of the reactor will go down. However, by changing the internals of the reactor (using a different type of trays) the efficiency in the reactor can be improved. In the past two types of trays were used in Stamicarbon Urea plants: the conventional trays and the high efficiency trays. Now a new type of trays is introduced, which improves the efficiency of the reactor and thus results in savings of the high-pressure steam consumption. These trays are called the Siphon Jet Pumps. The first trays have successfully been installed in SKW Piesteritz. In this paper the Siphon Jet Pumps are introduced and several aspects around these trays are discussed.

gas lines was again AISI316L-UG, because there were still some such tubes in stock, dating from the time the plant was constructed.The affected areas showed evidence of stress corrosion cracking (SCC), but reduction in the wall thickness was also observed. This was attributable to condensation corrosion, which is normally observed in the gas lines. It was most severe in the heat-affected zones (HAZ) near the welds. The affected elbows were subjected to metallographic examination in Brazil as well as in Stamicarbon laboratory. This paper presents the investigations carried out on the elbows and piping removed from the urea synthesis gas lines in order to find the root cause of the leakages. 

ia inside the process equipment is essential from a safety,environmental andeconomica lpoint of view

tripper performance.  The stripper level indication (Radioactive type) LT-1043 got erratic at our plant and we sustained plant operation without this indication by: 1. Keep the plant load constant and avoid any changes in plant load.  2. Observe the stripper outlet temperature as this temperature will change with increase or decrease of the stripper bottom level.  3. Observe the steam consumption of the stripper as the steam flow will change with a change in the liquid level. 4. Observe the N/C Ratio and keep it constant. 5. Observe the downstream section pressure at constant plant load.

long to the so-called accident plants. For these plants it is required that the security is improved constantly. The management wants to constantly improve the environmental-protection and upgrading the technological conditions to increase the production and to save energy.

n the system is checked by opening atmospheric valves and breaking the vacuum on a defined frequency of one month. We could not check the blockage on this defined frequency, we performed a blockage test after a period of 10 months; blockage was found in valves V-16 & V-17 in the leak detection system of the HP Stripper. After further investigation it revealed that the blockage in the leak detection system was inside the stripper top dome. We tried to de-block the system with instrument air having a pressure of 7 bar and with low pressure steam but this failed. Then on the running plant we tried to de-block using an argon cylinder having a pressure of 100 bar and de-blocked the lines at 30 bar. The root cause of the blockage was corrosion inside the leak detection tube due to moisture ingress through the atmospheric valves. The equipment condition was found healthy on inspection during a turnaround.

nless steel loose liners are commonly applied. With a loose liner a hazardous situation may arise if a leak occurs and carbamate containing fluids enters the space between liner and carbon steel. For this reason Stamicarbon designed a system which continuously monitors for leaks to allow safe operation of said equipment.

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Stripper replaced a bi-metallic designed Snamprogetti stripper in 2003 which suffered extreme corrosion issues within a short period after startup in the bottom channel section of the vessel that caused persistent operational outages and huge financial losses. The problems encountered with the original HP bi-metallic stripper and results of the decision to replace the bi-metallic tube stripper with a HP Safurex® stripper are addressed. The subject Safurex® stripper was in service for 850 operational days from March 2003 up until November 2006, after which the subject stripper was returned to Canada and installed in another Snamprogetti urea plant in 2007. The subject stripper has been in operation in Canada since 3Q 2007 and has had no issues in its new location as of this writing.

an producers • Investments drivers for North American projects • Key take-aways

-aways

d Training 6. Conclusions

t to boost yield, enhance the nutrients.

vely hit the market?

ttempts making such urea models have been limited in scope and usage, due to the rapid rise in complexity, execution time, and difficulties encountered as model size increases to encompass sufficient fidelity and scope to address overall economic impact to  the business. Urea plant models however can encapsulate a large amount of process knowledge and companies start realizing significant value from the use of these models in offline and online model based applications. Such applications include real-time optimization, model predictive control, data reconciliation, virtual sensors, process performance monitoring and total plant monitoring systems to name a few. This paper gives an overview on Stamicarbon’s capabilities and products related to urea plant modeling. These models are typically implemented in the ADVANCE and EVOLVE life-cycle of a urea plant. In the LAUNCH phase, grass root plants can apply the models to optimize consumption and emission figures.  It allows urea producers to stay competitive with production improvements, monitoring and detection, staff training and full lifecycle support. Further, feedback will be given on the EVOLVE OPTIMIZER™ project at OCI in the Netherlands. This has been in operation since 2012.

of the fertiliser product and/or the fertiliser application technology.