Recovery process, ammonia

Use vapor recovery systems to prevent air emissions from light oil processing, tar processing, naphthalene processing, and phenol and ammonia recovery processes. 

Ammonia Recovery Process, Chevron Research Co., U. S. Patent... 

Ostwald process for nitric acid, 13, 28, 66 Otto-Hilgenstock ammonia recovery process, 45... 

This carbon dioxide-free solution is usually treated in an external, weU-agitated liming tank called a "prelimer." Then the ammonium chloride reacts with milk of lime and the resultant ammonia gas is vented back to the distiller. Hot calcium chloride solution, containing residual ammonia in the form of ammonium hydroxide, flows back to a lower section of the distiller. Low pressure steam sweeps practically all of the ammonia out of the limed solution. The final solution, known as "distiller waste," contains calcium chloride, unreacted sodium chloride, and excess lime. It is diluted by the condensed steam and the water in which the lime was conveyed to the reaction. Distiller waste also contains inert soHds brought in with the lime. In some plants, calcium chloride [10045-52-4], CaCl, is recovered from part of this solution. Close control of the distillation process is requited in order to thoroughly strip carbon dioxide, avoid waste of lime, and achieve nearly complete ammonia recovery. The hot (56°C) mixture of wet ammonia and carbon dioxide leaving the top of the distiller is cooled to remove water vapor before being sent back to the ammonia absorber. 

Chevron s WWT (wastewater treatment) process treats refinery sour water for reuse, producing ammonia and hydrogen sulfide [7783-06-04] as by-products (100). Degassed sour water is fed to the first of two strippers. Here hydrogen sulfide is stripped overhead while water and ammonia flow out the column bottoms. The bottoms from the first stripper is fed to the second stripper which produces ammonia as the overhead product. The gaseous ammonia is next treated for hydrogen sulfide and water removal, compressed, and further purified. Ammonia recovery options include anhydrous Hquid ammonia, aqueous Hquid ammonia, and ammonia vapor for incineration. There are more than 20 reported units in operation, the aimual production of ammonia from this process is about 200,000 t. 

Manufacture. An extensive technology was developed initially ia the 1930s for isolation of ammonium thiocyanate from coke-oven gases, but this technology is no longer practiced ia the United States (372). However, such thiocyanate recovery processes are used iadustrially ia Europe. Likewise, the direct sulfurization of cyanides to thiocyanates is not practiced commercially ia the United States. The principal route used ia the United States is the reaction of carbon disulfide with aqueous ammonia, which proceeds by way of ammonium dithiocarbamate [513-74-6]. Upon heatiag, the ammonium dithiocarbamate decomposes to ammonium thiocyanate and hydrogen sulfide. 

For operations producing 30,000 tons or less of copper annuaHy, hydrometaHurgy offers an alternative to smelting that avoids problems associated with sulfur dioxide recovery and environmental controls. Techniques include the Anaconda oxygen—ammonia leaching process, the Lake Shore roast-leach-electrowin process, and ferric chloride leaching processes for the treatment of copper sulfides. AH the facHities that use these techniques encountered serious technical problems and were shut down within a few years of start-up. 

An electrostatic precipitator is used to remove more tar from coke oven gas. The tar is then sent to storage. Ammonia liquor is also separated from the tar decanter and sent to wastewater treatment after ammonia recovery. Coke oven gas is further cooled in a final cooler. Naphthalene is removed in a separator on the final cooler. Light oil is then removed from the coke oven gas and is fractionated to recover benzene, toluene, and xylene. Some facilities may include an onsite tar distillation unit. The Claus process is normally used to recover sulfur from coke oven gas. During the coke quenching, handling, and screening operation, coke breeze is produced. The breeze is either reused on site (e.g., in the sinter plant) or sold offsite as a by-product. 

Ammoniak-rest, m. ammonia residue (amidogen, NH2). -rohr, n. ammonia tube or pipe, -salpeter, m. ammonia saltpeter (ammonium nitrate), -salz, n. ammonium salt, -selfe,/. ammonia soap, -soda, /. ammonia soda, Solvay soda, -stickstoff, m. ammonia nitrogen. -verbindung, /, ammonia compound ammonium compound, -verfahren, n. ammonia process, -wasche, /. ammonia scrubbing ammonia recovery plant, -wascher,... 

HARP [Hybrid argon recovery process] A process for extracting argon from the hydrogen recycle stream in ammonia synthesis. Both PSA and a cryogenic process are used. Krishnamurthy, R., Lemer, S. L., and MacLean, D. M., Gas Sep. Purif, 1987,1, 16. 

Figure 15. Applications map for hydrogen recovery process A, ammonia purge gas B, refinery stream C, coal conversion recycle gas D, ethylene plant cracked gas E, FCC minus gas...

Recent developments in the ammonia oxidation process have included efforts to reduce catalyst losses in the process. Platinum recovery filters have been installed at various stages in the process. Gold/palladium gauze filter pads have been added on the exit side of the catalyst bed, inside the reactor/converter units. These filters have reportedly ensured a platinum recovery of 80% (Ref. PT4). Another trend has been for the use of additional filters in the downstream units. These filters are of alumino-silicate construction. 

Hydrometallurgical treatment of lateritic ores, by the reduction roast/ammonia leach process is one of the methods used for the recovery of nickel from low grade lateritic ores. In a recent study Chander and his associates (19, 20) used such... 

The process requires a large amount of fuel to calcine both the limestone and sodium bicarbonate and to generate steam for ammonia recovery. Large volumes of cooling water are required to remove the heat generated by the... 

HARP [Hybrid Argon Recovery Process] A process for extracting argon from the hydrogen recycle stream in ammonia synthesis. Both PSA and a cryogenic process are used. 

The recovery process is a vapor phase fixed-bed adsorption technology featuring desorption with ammonia. This process has paraffins recovery and product purity in the high 90% s. Ammonia is a very efficient desorbent. Since it is easily separated from the n-paraffins product, fractionation capital and energy requirements are substantially reduced. Furthermore, ammonia has the added advantage of protecting the adsorbents from coking. 

Qi and Cussler [26] investigated the removal of ammonia by H2SO4. H2SO4 being a strong acid, the mass resistance offered by the membrane controlled the process. An industrial membrane gas absorption unit for ammonia recovery from an ammonia containing off-gas stream produced in a dyes intermediates production plant has been installed by TNO. The membrane plant is able to remove 99.9% of ammonia and produces aqueous solutions of 27% ammonia that can be reused in the dyes process [38]. 

Saltpetre, Norwegian, 13, 27 plantations for, 12 prismatic, U Saturators, 40 Schimose, 100 Schlempe, 36, 72, 76 Schonherr furnace, 25 Schultr.e smokeless powder, 114 Securite, 103, 113 Serpek process, 57 Sewage, ammonia recovery from, 37 Shale, distillation of, 36 Siepermann s process. 73 Silesia powder, 104 Silicon, 104... 

Solvay process. (ammonia soda process). Manufacture of sodium carbonate (soda ash, Na O,) from salt, ammonia, carbon dioxide, and limestone by an ingenious sequence of reactions involving recovery and reuse of practically all the ammonia and part of the carbon dioxide. Limestone is heated to produce lime and carbon dioxide. The latter is dissolved in water containing the ammonia and salt, with resultant precipitation of sodium bicarbonate. This is separated by filtration, dried, and... 

Brine-disposal problems may be avoided by proposed modifications to the Solvay process, which employ magnesium hydroxide for ammonia recovery [17]. The magnesium chloride formed could be recycled and hydrogen chloride obtained as a coproduct by contacting the magnesium chloride with superheated steam (Eqs. 7.18 and 7.19). However, this process remains unproven. 

A second possibility is to add the mother liquor immediately after the digestion but prior to the purification steps. The disadvantage here is the presence of ammonium ions. As already pointed out, ammonium ions favor the condensation of tungsten ions, and this changes the properties and behavior of the isopolytungstate solution in the solvent extraction process. Therefore, this type of mother liquor recycling affords a separate pietreatment to expel the ammonia. This can be done by addition of NaOH and subsequent heating. The ammonia evolved can be fed into the ammonia recovery system of crystallization. The treatment produces a precipitate which can be separated by filtration. 

Phenol and Ammonia Recovery. Finally, the closely related passive and fa-cilitated-transport processes for phenol and ammonia recovery should be mentioned. In these processes, dilute phenol or ammonia feed solutions are contacted with a liquid membrane in which they are freely soluble. They dissolve in the membrane, diffusing to the product side where they are removed by neutralizing with a base (in the case of phenol) or an acid (in the case of ammonia). Although the transport mechanism does not involve a carrier and these are, therefore, passive transport processes, the actual process is quite similar, and Li et al25 published the details of these separations using emulsion membrane technique. 

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