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Driving nitrogen processes

Summary

The machinery that drives the reactants through ammonia, nitric acid and urea plants is very expensive and very important. We take a look at some of the developments.

Abstract

The processes used to manufacture ammonia and the immediate derivatives used in the manufacture of nitrogenous fertilizers – nitric acid and urea – all operate under various conditions of elevated pressure. The machinery used to deliver the reactants into these processes and to drive the process media through the plant is very sophisticated and expensive. Reliability is vital from the point of view not only of economic operation but also of safety.

In the case of ammonia, the reactions all take place between gaseous reactants in the gas phase, and the motive force driving the process media through the plant is therefore provided by compressors. The fundamental reaction in the nitric acid process is also between gaseous reactants, and the main requirement is again for compression, albeit at considerably lower pressure levels than in an ammonia plant. Liquid flows in and around the absorption section of a nitric acid plant can be handled by any good make of chemical pump provided the materials of construction have been sensibly selected.

Urea synthesis takes place under elevated pressure in a liquid environment, and under the conditions employed one reactant (ammonia) is fed in as liquid, while the other (carbon dioxide) is gaseous and requires compression. There are also important recycle loops within a urea plant entailing repressurization of aggressive liquid reaction media.

It is with the gas compressors and the specialized urea plant pumps that this article is concerned.

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MTO – has its time come?

Summary

With methanol facing some years of overcapacity and gas producers increasingly using the compound as a way of bringing stranded gas to market, methanol producers have been looking for alternative uses for their products in recent months. One of the possible technologies converts methanol into polyolefins. Nitrogen & Methanol looks at the prospects for MTO technology.

Abstract

Natural gas is used in a variety of ways – directly, as a fuel, or as a feedstock for chemical products, most notably ammonia and methanol. Gas prices for fuel use vary worldwide, but typically range from $0.50/mmBtu to $4.00/mmBtu. If converted to ammonia or methanol, the value of the gas improves to $4.00 to $6.00/mmBtu. However, if it could be converted to polyethylene or polypropylene on an equivalent carbon basis, the value rises to $7.00 – $10.00/mmBtu.

Natural gas is difficult and expensive to transport, requiring either long pipelines or expensive liquefaction units. The cheapest gas in the world is typically found associated with oil production, often in remote locations, often offshore, and frequently a long way from the nearest possible source of demand for gas as a fuel. As a result, such gas has historically often been uneconomical to collect and has either been flared or reinjected.

Increasing environmental regulations and taxes on flaring are forcing producers to look at new ways of utilising this remote gas. At the moment, the favoured tactic is to convert it to the much more easily transportable methanol. However, this has produced a glut of cheap methanol on the world market, with no sizeable source of new demand for it on the horizon.

The search has therefore been on for a use for this methanol, and while fuel cells, water treatment and other uses are on the horizon, one possibility which has emerged in recent years is the conversion of methanol to polyolefins.

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SC's SCs

Summary

Around 80 guests attended Süd-Chemie's Syngas Catalysts Millennium Seminar in Lisbon in May. Nitrogen & Methanol was invited to eavesdrop on the proceedings.

Abstract

Süd-Chemie was founded in 1857 as a fertilizer manufacturer in Upper Bavaria, close to the Alps. The famous German chemist and pioneer of chemical fertilization Justus von Liebig was one of the co-founders. Today Süd-Chemie is a globally operating company with an annual group turnover of DM 1.5 billion. ($750 million). A major part of this is attributable to sales of catalysts, of which Süd-Chemie produces a wide range.

Within Süd-Chemie’s catalyst portfolio is a full range of catalysts for production of ammonia and methanol synthesis gas as well as methanol synthesis catalyst (Süd-Chemie does not manufacture ammonia synthesis catalyst). It was these catalysts and their application that was the principal focus of Süd-Chemie’s Millennium Seminar on Catalysts and Technology, held in Lisbon at the Hotel Sheraton Lisboa from 10–12 May this year. Before a total audience of about 95, a panel of speakers from Süd-Chemie, its operating customers and its engineering associates gave a series of presentations encompassing the state of the art of Süd-Chemie catalysts and the associated process technology, as well as some operational experience from actual plants using them.

The seminar convened on the evening of 10 May with a reception sponsored by Lurgi Öl·Gas·Chemie. This was held in the restaurant at the top of the hotel, from which attendees were able to enjoy a spectacular view over the city. The following evening delegates were taken by bus for dinner in a former royal pavilion, with hosts and waiters in eighteenth-century costume in attendance.

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Urea technology symposium

Summary

Stamicarbon's 9th urea symposium was held in Amsterdam in the Netherlands from 8th – 11th May.

Abstract

Dutch urea technology supplier Stamicarbon have been running an annual urea technology symposium for nine years now. The conference aims to promote the development of better technology for urea production. The symposium is also a forum for the exchange of ideas within the urea industry. There were a total of 32 papers presented, 16 of which were from the hosts, and the other 16 from associated companies. As well as operator experiences from Kaltim, Iffco, Agrium, Ultrafertil, Sinopec, Saskferco, DSM and the Zhenhai Refining Chemical Co of China, several technical papers were presented on a variety of subjects.

Two papers covered the subject of monitoring and inspection, while another tackled quality control. K Jonckers of Stamicarbon also presented an overview of new developments in the Urea2000plus process which, it is claimed, will reduce energy consumption by 20%, by an improved heat recovery unit, more efficient use of high pressure steam from the pool reactor, and reintroducing a medium pressure recirculation stage which also acts as pre-evapourator.

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Under pressure: documentation of ammonia relief valves

Summary

Steve Kent of Mustang Tampa Inc describes the steps necessary for proper documentation of relief valves for ammonia handling facilities under OSHA regulations.

Abstract

In May 1992, the US Occupational Safety and Health Administration (OSHA) promulgated as a final standard 29 CFR 1910.119 – Process Safety Management of Highly Hazardous Chemicals. In the United States, the provisions of the standard are mandatory for all covered processes. The purpose of the standard is to prevent or minimize the consequences of the catastrophic release of toxic, reactive, flammable or explosive chemicals. For a covered process, the standard consists of 13 mandatory subparts which, taken together, provide the necessary framework for the management of facilities that process hazardous materials. Each subpart requires specific, documented action on the part of the facility owner.

Fertilizer plants use ammonia in the production of monoammonium phosphate (MAP) and diammonium phosphate (DAP). Ammonia handling facilities in these plants typically consist of pressurized storage vessels, pumps, heaters and vaporizers. Because ammonia is a listed chemical in 29 CFR1910.119, the ammonia handling facilities become a covered process subject to the requirements of the act.

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