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Publication > Issue > Articles

Multi-stage scrubbing for granulators and prilling towers

Summary

Stamicarbon and EnviroCare have co-developed a multi-stage process for the efficient scrubbing of urea particulate and ammonia from both granulator and prilling tower technologies. These gas scrubbers are designed to achieve extremely high efficiencies and to meet stringent emission levels, while keeping pressure drop low to minimise energy consumption. W. Dirkx of Stamicarbon and B. Higgins of EnviroCare International discuss the key features and performance of the scrubbing technology.

Abstract

Urea prills and granules are produced from highly concentrated urea melt solutions. When the melt is sprayed into a prilling tower or a granulation unit, there will be evaporation of decomposition products from urea (for instance ammonia and isocyanic acid). Air is used to cool the final product. The off-gas must be cleaned before it is released into the atmosphere because it will contain urea dust, ammonia, and various decomposition products of urea. To reduce air pollution, the off-gas is scrubbed using an aqueous solution that is circulated in the scrubber until it has the desired concentration of urea (e.g., 45 wt-%). The concentrated urea solution is blown down for reuse. Keywords: urea dust, ammonia removal, urea particulate, granulation, prilling, gas scrubber, emissions, urea prills, urea granules, prilling tower, granulator, dust emissions, ammonia emissions, MicroMist Venturi, MMV, SpiralMist, urea quench, tray conditioning, acidic scrubbing, mist elimination, scrubber retrofit, jet scrubber, seeding, Advance Coat, coating technology, Stamicarbon, EnviroCare International

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Toyo's high efficiency scrubbing systems

Summary

K. Sato of Toyo Engineering Corp. reports on Toyo's approaches and latest technologies to reduce ammonia and urea in emissions from urea plants. Case studies for two recent large-scale urea granulation plants are presented.

Abstract

Nowadays, environmental protection is one of the most important issues for any production facility and the urea plant is no exception. Environmental guidelines and regulations continue to become ever more stringent in response to growing public concern. Toyo Engineering Corporation, a leading process licensor of urea production technologies, has developed and applied its own scrubbing technologies using water and/or acid for the abatement of urea dust and gaseous ammonia emissions from urea plant finishing sections. Typical emission guidelines for urea dust and ammonia applied to the urea plant finishing section are 50 mg/Nm3 urea dust and 50 mg/Nm3 ammonia. Keywords: urea plant scrubbing, urea granulation, acid scrubbing, water scrubbing, ammonium salt urea dust, ammonia emission, UAS, AS, fertilizer, Kaltim, Indorama, Toyo, emissions

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Meeting tougher US emissions requirements

Summary

The first large scale urea fluid bed granulation plants utilising a new horizontal scrubbing system, jointly developed by Kimre , tkIS and UFT, are now in operation in the US. Dr H. Franzrahe of UFT, M.M. Schmitz of tkIS and M. Davidson of Kimre describe the scrubbing systems and report on the record low emission levels being achieved.

Abstract

Lower natural gas prices in the US have stimulated the construction of new urea plants and with recent focus on the health impacts of fine airborne particulate, the permitted emission limit values negotiated between plant sites and local environmental authorities are tougher than ever. Urea dust is characterised as “particulate matter”, one of six criteria air pollutants regulated by the US Environmental Protection Agency (EPA) which established requirements for PM10 (particulate matter with aerodynamic diameter of 10 microns or less) and PM2.5 (particulate matter with aerodynamic diameter of 2.5 microns or less). Keywords: urea fertilizer finishing, scrubbing, urea fluid bed granulation, horizontal scrubing, Kimre, semi-cross flow scrubber, SXF, urea dust, particulate, urea granulation retrofit, emission limits, UFT, tkIS, CF Industries, Urea-ES.

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Steam methane reformer improvements

Summary

Today's state-of-the-art reformers are considerably different to their original predecessors that were established in the 1930s. Factors such as the availability of new materials, improved methods of catalyst manufacture, developments in reformer design, advances in computational modelling and improved operational regimes have all contributed to the vast improvements that have been realised.

Abstract

Steam methane reforming is a critical operation and can be considered as the heart of any ammonia, hydrogen or methanol plant. The conversion of methane, or other hydrocarbon feedstocks, into a synthesis gas mixture is a challenging operation, both chemically and physically. Due to the complex nature of steam methane reforming there are many conflicting demands, hence ensuring that the process is accomplished both efficiently and reliably is something that involves continuous improvements that reflect the latest technological capabilities. Keywords: primary reformer, steam methane reforming, heat resistant steels, Manaurite, catalyst tubes, creep resistance, carbides, creep strength, carbide distribution, austenitic matrix, reformer tube metallurgy, rupture strength, tube wall thickness, tube material, Purifier process, gas turbine, modelling, catalyst simulation, QUADRALOBE, packing, CFD modelling, catalyst, pellet shape, CATACEL, REFORMAX. Manoir Industries, KBR, Johnson Matthey, Clariant, thyssenkrupp Industrial Solutions.

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Plant Manager+ Problem No. 42: Coated urea fertilizers

Summary

Coating urea prills (granules) with a water-insoluble, semipermeable, or impermeable (with pores) material delays the release of nitrogen from the urea. Urea is highly soluble in water, but the solubility of coated urea is dependent on the coating material, its thickness, and the coverage and uniformity of the coating on the granule. As the urea is gradually released from the coated granule, it is exposed to the same chemical and biological processes as non-coated urea. Coated urea provides a safer and more efficient form of urea by: l safeguarding against nitrogen losses through volatilization and degradation; l slowing down leaching due to its slow-release characteristics; l improving stability in fertilizer blends.

Abstract

Amirhossein Hadian from Khorasan Petrochemical company, Iran starts the roundtable discussion: I am researching coated urea fertilizers – controlled release fertilizers consisting of urea prills, coated with less-soluble chemicals such as sulphur, polymers, etc. Does anyone have any suggestions for coating urea prills to slow down dissolution rates when used on farms? Keywords: coating, urea prills, urea granules, controlled release fertilizers, neem, neem-coated urea, anticaking agent, germicide.

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Methanol as a shipping fuel

Summary

The approach of new IMO regulations on marine fuels in 2020 presents an opportunity for methanol to make inroads into a new and potentially lucrative global fuels market, if concerns over pricing and distribution can be overcome.

Abstract

Global methanol demand has more than doubled over the past 20 years, as economies of scale have allowed the production of methanol at ever-larger facilities, bringing down the unit cost and allowing it to break through from its traditional chemical markets into new fuel uses. Particularly in China, which now consumes half of the world’s methanol, it has become an important blendstock in gasoline, and a source for dimethyl ether (DME), which is blended in LPG. There are methanol and DME fuel trials and mandates in a number of countries an Keywords: HFO, IMO, distillate, sulphur, SOX, NOX, MGO, obate, Methanex, MI, gasoil, DNV, diesel, ship, vessel, engine

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Overcapacity continues to stalk urea markets

Summary

In spite of a dramatic fall in Chinese production and exports due to higher coal prices, continuing additions of new urea capacity worldwide continue to keep the market oversupplied.

Abstract

Urea remains the bellwether for nitrogen prices – of the approximately 150 million tonnes of nitrogen produced as ammonia in 2015, around half was used for the manufacture of urea. Urea is preferentially shipped to ammonia as a dry bulk commodity with a high nitrogen content (46% w/w) and remains the key nitrogen fertilizer. Keywords: China, India, coal, anthracite, bituminous, trade, US, United States, investment, capacity, surplus, closure, price

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Caribbean nitrogen and methanol

Summary

The rebirth of the US nitrogen and methanol industries due to cheap shale gas has coincided with gas supply issues on Trinidad and Venezuela's continuing political paralysis, and is likely to force more ammonia and methanol out onto the global market.

Abstract

If any region illustrates how closely tied to the natural gas industry the methanol and ammonia and downstream industries are, it is surely the Caribbean. During the late 1990s and early 2000s, as high gas prices began to force US domestic producers to close down or relocate, Trinidad, and to a lesser extent Venezuela became the main beneficiaries, having as they did at the time ample supplies of cheap natural gas with which to feed new ammonia and methanol plants, and able to easily supply the large US market on their doorstep. But the past decade has seen a complete reverse of the situation. Trinidad now finds itself overcommitted in terms of natural gas resources, while the slump in domestic US gas prices caused by shale gas drilling has led to re-starts of mothballed facilities and a number of new projects. Keywords: Trinidad, Venezuela, Gulf Coast, US, United States, olefins, MTO, UAN, nitrate, gas, LNG

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