Ammonia recovery

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. 

The reactor effluent, containing 1—2% hydrazine, ammonia, sodium chloride, and water, is preheated and sent to the ammonia recovery system, which consists of two columns. In the first column, ammonia goes overhead under pressure and recycles to the anhydrous ammonia storage tank. In the second column, some water and final traces of ammonia are removed overhead. The bottoms from this column, consisting of water, sodium chloride, and hydrazine, are sent to an evaporating crystallizer where sodium chloride (and the slight excess of sodium hydroxide) is removed from the system as a soHd. Vapors from the crystallizer flow to the hydrate column where water is removed overhead. The bottom stream from this column is close to the hydrazine—water azeotrope composition. Standard materials of constmction may be used for handling chlorine, caustic, and sodium hypochlorite. For all surfaces in contact with hydrazine, however, the preferred material of constmction is 304 L stainless steel. 

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. 

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. 

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

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,... 

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

The next step.was the removal of ammonia from the crude soln , which was done by steam-stripping in an evaporator to an ammonia recovery system, where NH, was absorbed in w. The resultant NH,-free crude soln was filtered through a Nutsch type filter to remove the catalyst and other insol impurities. The filtrate referred to as clear liquor was stored in a 1000 gal tank from which it could be transferred by suction into either of two 280 gal jacketed evaporators. The evaporation was conducted under 24" vacuum with 50 lb steam press in the jacket. A total of 425 gal of "clear liquor was concentrated until a sample of its "mother liquor showed the strength of 35% NaOH. During this operation the bulk of NaN, being less sol in w than NaOH, pptd. Then the mixt was cooled to 80-90°F (27-32°) (to cause the pptn of addnl NaN,) and dropped to a wringer. The yield was ca 75% NaN, and the overall cycling time was 5 6 hrs... 

By using the rectangular transverse-flow module developed by TNO (The Netherlands), an industrial membrane gas absorption unit for ammonia recovery has been installed in The Netherlands [21]. Also, a unit for C02 removal has been tested [22]. 

In contrast to DAP production, ammonia recovery by acid scrubbing is not necessary, but all off-gases are scrubbed to recover dust and fumes. Granular plants can thus be simpler, but most units are designed so that both products can be made in the same plant296. 

Employing a reusable solvent for ammonia recovery could suppress the treatment of a large amount of wastewater. For an ROI of two years the investment in treating the sour water would be of 490 x 8400 x 2 = 8.23 M. ... 

Corrosion problems were observed with stainless steel tubing of a high-pressure still condenser employed for ammonia recovery. The feed solution in the high-pressure still is typically 135 g/L ammonia and 4.7 g/L C02. Figure 7.71 shows a simplified view of the high-pressure still (HPS) and condenser. 

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... 

A) Synthesis loop for pure and dry makeup gas B) Product recovery after recycle compression C) Product recovery before recycle compression (four-nozzle compressor design) D) Two stages of product condensation a) Ammonia converter with heat exchangers b) Ammonia recovery by chilling and condensation c) Ammonia recovery by condensation at ambient temperature d) Synthesis gas compressor e) Recycle compressor... 

Ammonia recovery by adsorption on solids has been also proposed [1498], [1499]. 

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]. 

Ion exchange ammonia recovery, 495 chromate recovery, 495 deionization of water, 29 heavy metal removal, 495... 

Colliery steelite, 104 Concentrated ammonia water, 45 Coppiie ammonia recovery plants, 41, 42, 45. 46... 

Kalkstickstoff, 61, 78 Kieselguhr, 97 — dynamite, 97, 98 King s Norton Metal Co., 106 Kopper ammonia recovery plant, Kynite, 113... 

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

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... 

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