Abstract:
Disclosed is a method for urea finishing. A urea solution is subjected to crystallization and, other than in conventional processes, the urea crystals are shaped by exerting mechanical force onto them. Thus, the conventional prilling or granulation finishing steps can be avoided, and so are the corresponding emissions of ammonia and/or dust. The crystallization comprises a flash crystallization. The invention also pertains to the urea particles obtainable by the process, to a urea plant, and to a method of modifying an existing urea plant.
Abstract:
Disclosed is a process for the concurrent production of hydrogen and sulphur from a H 2 S-containing gas stream, with zero emissions. The method comprises the thermal oxidative cracking of H 2 S so as to form H 2 and S 2 . Preferably, the oxidation is conducted using oxygen-enriched air, preferably pure oxygen. The ratio H 2 S/O 2 in the feedstock is higher than 2:1, preferably in the range of 3:1-5: 1.
Abstract translation:公开了一种从含H2S的气流同时生产氢和硫的方法,零排放。 该方法包括H2S的热氧化裂化,形成H2和S2。 优选地,使用富氧空气,优选纯氧进行氧化。 原料中H 2 S / O 2的比例高于2:1,优选在3:1-5:1的范围内。
Abstract:
Disclosed is a method for the production of urea allowing a substantial reduction, even down to zero, of the continuous emission of ammonia conventionally resulting from such a process. According to a preferred embodiment of the invention, the urea-forming reaction from carbon dioxide and ammonia is conducted in a synthesis section that does not require passivation by oxygen. As a result of the absence of oxygen, a hydrogen-rich gas stream results from the synthesis section, that can be used as a fuel in an incinerator. In the incinerator, ammonia-comprising gas streams from the urea production process are combusted.
Abstract:
The invention relates to a process for producing urea wherein an aqueous urea solution, leaving a urea reaction zone is fed to a stripper, where a part of the non-converted ammonia and carbon dioxide is separated from the aqueous urea solution, which solution leaves the stripper to a first recovery section of one or more serial recovery sections and is subsequently fed to one or more urea concentration sections, wherein the urea solution leaving the stripper is subjected to an adiabatic expansion, thus creating a vapor and a liquid, which are separated before the liquid enters a first recovery section and the vapor is condensed. The invention further relates to a urea plant comprising a stripper and a first recovery section, wherein an adiabatic expansion valve and a liquid/gas separator is provided between the stripper and the first recovery section.
Abstract:
The invention relates to a process for the manufacture of a tubular composite part whose longitudinal axis exhibits a curve and/or whose wall exhibits a variable cross section relative to the longitudinal axis in which process, a tubular semi-finished product, comprising an uncured or a partially cured resin and fibre reinforcement and further comprising an inflatable former, is introduced into a mould, a medium is brought into the inflatable former under pressure, the resin being cured and the composite part thus obtained being removed, characterized in that the fibre reinforcement comprises at least a knitted or braided sleeve. Composite parts according to the invention can be used in numerous applications where complex structural parts are required that combine high pressure-resistance, flexural, torsional and tensile strength. Such an application is sometimes referred to as a space frame. Examples are the supporting parts in a car body or in a boat or aircraft, in construction, rucksack frames, bicycle frames, lampposts and sports equipment, such as bobsleighs, etc.
Abstract:
Polytetramethylene adipamide resin compositions containing 100 parts by weight of the polyamide and 2 to 20 parts by weight of a silicon oil. Objects produced from the composition possess good surface appearance, excellent sliding properties and high heat resistance and rigidity.
Abstract:
Process for the spraying of a liquid by means of a gas into a fluidized bed, in which process said spraying is conducted by means of a two-phase spraying device, consisting of a liquid feed tube (21) fitted concentrically in a gas feed tube (26), in which device the end face of the liquid feed tube and the inner wall of the part of the gas feed tube extending beyond this end face are chamfered at an angle of 70-90 so that between this face and this wall there is a conical channel, and this inner wall connects, via a rounded area, to the inner wall of an outflow channel fitted coaxially in respect of the liquid feed tube, of which channel the inside diameter is 1 to 1.6 times the inside diameter of the outflow opening of the liquid feed tube and 2.5 to 10 times the curvature radius of the rounded area. To prevent erosion due to fluctuations in the process or to small changes in the design of the sprayer the invention is characterized in that the outflow channel (31), seen into the direction of flow, is conically narrowed.
Abstract:
The disclosure pertains to an urea production plant and process using a thermal stripper, wherein the reaction mixture is separated in two parts, wherein the first part is supplied at least in part to the thermal stripper and the second part at least in part bypasses the thermal stripper and is supplied to a medium pressure recovery section.
Abstract:
The invention pertains to a finishing process for urea-comprising material, a plant for finishing urea-comprising material, a method of modifying an existing plant, and a use. Methods are disclosed for preventing the clogging of the conduit for off-gas between the finishing section and the treatment section.
Abstract:
Disclosed is a method of making a granulate of a urea product comprising urea and a salt, such as urea ammonium sulfate, having a high content of the salt. The high content is such as to provide an amount of the salt above the limit of solubility of the salt in urea. The granulate of the invention is characterized by having a smooth surface, which, e.g. in the event of urea ammonium sulfate, is not normally the case for granulate having the aforementioned high ammonium sulfate content. According to the invention this is realized by dividing the feed liquids to granulation. This division is based on non-final granulation liquids of a sufficiently high content of the salt, and a final granulation liquid (determining the surface) having a salt content of below the solubility limit of the salt, or no salt at all. E.g. in the event of urea ammonium sulfate, the non-final granulation liquids possibly are a slurry of urea and more than 20 wt.% of ammonium sulfate. The final granulation liquid then has 0-20 wt.% of ammonium sulfate, i.e. below the solubility limit.