Pipe reactor

Fig. 23. TVA pipe reactor system for production of 10—34—0 or 11-37-0 base solution from low conversion superphosphoric acid.

Fig. 25. TVA pipe reactor process for production of 9-32-0 and 12-36-0 grade base suspensions directly from wet-process orthophosphoric acid.

Corrosion. Copper-base alloys are seriously corroded by sodium thiosulfate (22) and ammonium thiosulfate [7783-18-8] (23). Corrosion rates exceed 10 kg/(m yr) at 100°C. High siUcon cast iron has reasonable corrosion resistance to thiosulfates, with a corrosion rate <4.4 kg/(m yr)) at 100°C. The preferred material of constmction for pumps, piping, reactors, and storage tanks is austenitic stainless steels such as 304, 316, or Alloy 20. The corrosion rate for stainless steels is <440 g/(m yr) at 100°C (see also Corrosion and corrosion control). 

The reactor is a pipe reactor heated with fuel gas, gross calorific value 33.5 MJ/m3. Estimate the quantity of fuel gas required. 

InTox A process for destroying toxic wastes in aqueous solution by oxidation with oxygen at high temperatures and pressures in a pipe reactor. No catalyst is required. The reactions take place at approximately 300°C and 120 atm. Developed by InTox Corporation, UK, based on a process for extracting aluminum from bauxite developed by Lurgi in the 1960s. See also Zimpro. 

VAW Lurgi [Vereinigte Aluminiumwerke] An energy-efficient process for extracting aluminum from bauxite. Extraction is done in a pipe reactor, and the aluminum hydroxide is converted to the oxide in a fluidized bed. 

The production of toluene from benzene and xylenes was studied by Johanson Watson (National Petroleum News, 7 Aug 1946) in a standard 1-inch pipe reactor with a silica-alumina catalyst. At the reaction temperature of 932 F (773 K) the reaction mixture was vapor phase, but the feeds were measured as liquids. The feed consisted of an equimolal mixture of reactants. The stated LHSV is (ml feed at 60 F/h)/(ml reactor). The reactor contained 85 g catalyst packed in a volume of 135 ml. The densities of benzene and xylenes at 60 F are 0.879 and 0.870, respectively. 

A continuous bulk polymerization process with three reaction zones in series has been developed. The degree of polymerization increases from the first reactor to the third reactor. Examples of suitable reactors include continuous stirred tank reactors, stirred tower reactors, axially segregated horizontal reactors, and pipe reactors with static mixers. The continuous stirred tank reactor type is advantageous, because it allows for precise independent control of the residence time in a given reactor by adjusting the level in a given reactor. Thus, the residence time of the polymer mixtures can be independently adjusted and optimized in each of the reactors in series (8). 

Powdered niobium metal, 20.0 g. (—200 mesh), and tin(II) fluoride, 52.0 g. (40 mesh),t are mixed in a molybdenum crucible in an Inconel- or nickel-pipe reactor approximately 3 in. in diameter and 10 in. long and heated to 400-500°C. in a stream of dry nitrogen. The niobium(V) fluoride volatilizes from the reaction mixture and condenses on the water-cooled lid of the reactor, which leaves metallic tin in the crucible. The yield of niobium(V) fluoride is 21.1 g., or 95% of theoretical. A very small amount of blue niobium oxyfluoride (composition of variable oxygen and fluorine content) often forms as an impurity because of the presence of minute amounts of oxygen. Anal. Calcd. for NbFs Nb, 49.44 F, 50.56. Found Nb, 49.43 F, 50.2. 

For larger quantities the above procedure is used with a greater number of silicon(IV) fluoride elimination steps. Fifty-gram batches have been prepared by scaling up this technique and using a larger metal-pipe reactor. 

Continuous reactors, including simple plug-flow pipe reactors, tubular reactors containing static or other mixing devices, and jet reactors of various types, have been used to efficiently produce toxic materials for immediate consumption in downstream processing operations with little or no inventory. Some examples follow. 

Neutralizers may be free-boiling vessels, circulating systems or pipe reactors. The water in the nitric acid is evaporated by the heat of reaction (550 to 620 BTU/lb of AN, depending on the acid strength). At least ten different types and designs of neutralizers are used in Europe. The factors that influence the choice of neutralizer are103 ... 

Pipe Reactor Plus Fluidized Drum Granulator... 

The AZF pipe reactor process from La Grande Paroisse was combined with the fluidized dram granulator process from Kaltenbach-Thiiring S.A. The design melt concentration from the plant is 92% with 94% being achievable. The steam from the process is used to preheat the nitric acid feed and to vaporize the ammonia feed229. 

Alternative processes based on the use of a pipe reactor instead of a tank reactor were developed by Gardinier S.A., Swift Agricultural Chemical Corporation (see Figure 12.3), and ERT - Espindesa. Product humidity is reported to be as low as 2 %, which results in less caking296. 

Based on the favorable results obtained with a pipe reactor for MAP powder manufacture, ERT - Espindesa experimented with the production of DAP powder (see Figure 12.4). The DAP product has a remarkably high water- and citrate-soluble P2O5 content. This is probably due to the short residence time in the reactor, which does not yield the insoluble salts that are normally formed in long-retention-time DAP plants. The same effect has been observed with MAP formed in a pipe reactor295. 

In an attempt to further simplify DAP plants and reduce the recycle ratio, TVA, CROS S.A., and ERT - Espindesa have tried to use pipe reactors (also called T reactors or pipe-cross reactors) directly releasing slurry in the rotary granulator, instead of applying a preneutralization tank. CROS and ERT -Espindesa report successful operation, but experiences in several U.S. plants were disappointing because of high heat input in the granulator296. 

CdF-Chimie AZF had the same experience at first, but succeeded by installing a second pipe reactor to spray solution into the dryer (see Figure 12.6). 

Approximately half of the phosphoric acid is fed to a pipe reactor that operates at N/P =1.4 and releases its product into the granulator. The remaining acid is fed into a second pipe reactor at N/P =1.1 that sprays into the dryer. Extra ammonia is introduced underneath the rolling bed in the rotary drum granulator296. 

The pipe reactor in the dryer produces MAP powder. Part of it is carried away into the cyclones of the dedusting loop. The remainder crystallizes on the DAP product. The recycle ratio of this process is lower than with a conventional preneutralizer, and fuel consumption in the dryer is also reduced296. 

The pipe reactor processes have been very successful in MAP production. They operate with a very slight ammonia loss, and little or no additional heat is required for drying. In some plants, preneutralizers have been replaced by pipe... 

At this point, one will ask whether or not the demand for Re = idem is justified. In the last instance we are dealing with a fast reaction if we have selected a tubular reactor. Consequently, the flow through this pipe reactor will certainly be turbulent. It is well known that Re only has a slight influence in the turbulent flow regime ... 

Use of a Pipe Reactor (Melt Granulation). A more recent development that has been adopted in most U.S. granulation plants involves the substitution of a pipe reactor or a pipe-cross reactor for the preneutralizer vessel as the locale for the ammonia-acid... 

The most popular scheme by which solution-type fertilizers are made from low-conversion, wet-process superphosphoric acid is outlined in Fig. 24.20. The first step is ammoniation of the acid to produce ammonium polyphosphate base solution. By carrying out this ammoniation in a pipe reactor, a temperature of over 200°C is developed, which promotes an increase in polyphosphate content to 65-70 percent of total P2Os in the ammoni-ated acid.39,40 The grade of the resultant base is usually 10-34-0 an 11-37-0 grade can be made, but its storage properties are not as... 

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