Rob Stevens

Yara runs a 1400MTPD ammonia plant in Porsgrunn as feedstock for further downstream processing into nitric acid and NPK( Yara’s nitrophosphate process). The ammonia plant dates from 1968 and is a Humphrey’s & Glasgow design, revamped in 1997 by Kellog. Synthesis and CO2 removal are own design. The feed based upon ethane/propane/butane mixtures, whereas the fuelgas can include carbon monoxide rich gas.
Due to instability in the carbon dioxide removal process operational personal had problems… Vis mer

Yara runs a 1400MTPD ammonia plant in Porsgrunn as feedstock for further downstream processing into nitric acid and NPK( Yara’s nitrophosphate process). The ammonia plant dates from 1968 and is a Humphrey’s & Glasgow design, revamped in 1997 by Kellog. Synthesis and CO2 removal are own design. The feed based upon ethane/propane/butane mixtures, whereas the fuelgas can include carbon monoxide rich gas.
Due to instability in the carbon dioxide removal process operational personal had problems in keeping the ammoniaplant in stable operations. In an ultimate attempt in keeping the front-end in operation the methanator was bypassed, after a high temperature trip. Bypassing the methanator is an option which can be exercised in many ammonia plants, with or without the use of a flare up- or downstream the methanator.
Due to a combination of circumstances carbon dioxide rich gas reached the synthesis gas compressor.
The sequence of events leading to the stop of the plant will be discussed, including the findings and measures to avoid an event like this. Vis mindre

Yara runs a 1400MTPD ammonia plant in Porsgrunn as feedstock for further downstream processing into nitric acid and NPK( Yara’s nitrophosphate process). The ammonia plant dates from 1968 and is a Humphrey’s & Glasgow design, revamped in 1997 by Kellog. Synthesis and CO2 removal are own design. The feed based upon propane\butane mixtures, whereas the fuelgas can include carbon monoxide rich gas.
Due to unforeseen circumstances the plant experienced in 2008 a frequent leakage of the reformer… Vis mer

Yara runs a 1400MTPD ammonia plant in Porsgrunn as feedstock for further downstream processing into nitric acid and NPK( Yara’s nitrophosphate process). The ammonia plant dates from 1968 and is a Humphrey’s & Glasgow design, revamped in 1997 by Kellog. Synthesis and CO2 removal are own design. The feed based upon propane\butane mixtures, whereas the fuelgas can include carbon monoxide rich gas.
Due to unforeseen circumstances the plant experienced in 2008 a frequent leakage of the reformer tubes into the furnace itself. In order to avoid a full stoppage and the availability of external access the practice of nipping the pigtails outlet reformer was practised.
Certain routines were established to do the nipping exercise in a safe way, having no leakages to the surroundings, nor endangering the people involved. However during one nipping exercise the pigtail ruptured and an explosive fire occurred, fortunately without injuries.
In this paper it will be discussed on how the routines were established in a procedure and how this procedure was improved to reduce the risks even more, even focussing on nipping training for all those involved Vis mindre

Qatar Fertilizers Company (QAFCO), Ammonia-3 is a 1,500 metric tons per day (MTPD) plant, designed, supplied, and commissioned by a company (Division of Thyssen Krupp Group) (UHDE) in 1997. The main gas flare stack is a self-supported free-standing structure with a height of 70.5 m, located in the middle of the plant. Excessive vibrations/shaking of the flare and flare structure were observed due to mixing of NH3 and CO2 rich gases in the presence of water. Ammonium carbonate and bicarbonate… Vis mer

Qatar Fertilizers Company (QAFCO), Ammonia-3 is a 1,500 metric tons per day (MTPD) plant, designed, supplied, and commissioned by a company (Division of Thyssen Krupp Group) (UHDE) in 1997. The main gas flare stack is a self-supported free-standing structure with a height of 70.5 m, located in the middle of the plant. Excessive vibrations/shaking of the flare and flare structure were observed due to mixing of NH3 and CO2 rich gases in the presence of water. Ammonium carbonate and bicarbonate sludge (salts) formed in the flare stack and increased resistance to the gas flow path. The partial blockage increased the pressure at the flare-stack bottom and the sudden release of the gases gave vibrations (surging effects) to the flare stack. The flare stack was drained after unplugging the stack-bottom drains. Hot-process gases (167°C) from the low temperature shift converter (LTS) outlet were lined up to the flare stack in small quantity to melt the deposits. Flare vibrations completely stopped after 3 days. Inspection of the weld joints and foundation bolts was done, and no abnormalities were found. No vibrations were observed during all normal/emergency plant shutdowns faced after the incident. The work describes the root cause of unique experience of flare-stack vibrations, and the way the problem was solved online. © 2010 American Institute of Chemical Engineers Process Saf Prog, 2010 Vis mindre

Near-critical fluids can be applied as solvents for performing enzyme catalysis. Understanding enzymatic reactions in near-critical fluids is only possible when the phase behaviour of the reactants in the near-critical solvent and other physicochemical aspects, such as water isotherms and kinetics are known. In this thesis these effects are studied using a multidisciplinary approach in which thermodynamics, enzymologie and process engineering are integrated. Five different enzymes have been… Vis mer

Near-critical fluids can be applied as solvents for performing enzyme catalysis. Understanding enzymatic reactions in near-critical fluids is only possible when the phase behaviour of the reactants in the near-critical solvent and other physicochemical aspects, such as water isotherms and kinetics are known. In this thesis these effects are studied using a multidisciplinary approach in which thermodynamics, enzymologie and process engineering are integrated. Five different enzymes have been tested and modeled in a hydrolysis reaction of ten different substrates. Experiments and modelling were performed on the vapour-liquid phase behaviour of binary systems of interest for enzymatic reactions in near-critical fluids. Vis mindre