Stripping process

The urea produced is normally either prilled or granulated. In some countries there is a market for Hquid urea—ammonium nitrate solutions (32% N). In this case, a partial-recycle stripping process is the best and cheapest system. The unconverted NH coming from the stripped urea solution and the reactor off-gas is neutralized with nitric acid. The ammonium nitrate solution formed and the urea solution from the stripper bottom are mixed, resulting in a 32—35 wt % solution. This system drastically reduces investment costs as evaporation, finishing (priQ or granulation), and wastewater treatment are not required. 

Stamicarbon GO2 Stripping Process. In the early 1960s, Stamicarbon introduced the first stripping process. One of the main... 

Fig. 3. Stamicarbon CO2 stripping process. TCW — tempered cooling water.

Fig. 4. Pool condense type synthesis section foi Stamicaibon CO2 stripping process.

Fig. 5. Pool condenser vessel for Stamicarbon CO2 stripping process.

The bottoms from the stripper (40—60 wt % acid) are sent to an acid reconcentration unit for upgrading to the proper acid strength and recycling to the reactor. Because of the associated high energy requirements, reconcentration of the diluted sulfuric acid is a cosdy operation. However, a propylene gas stripping process, which utilizes only a small amount of added water for hydrolysis, has been described (63). In this modification, the equiUbrium quantity of isopropyl alcohol is stripped so that acid is recycled without reconcentration. Kquilibrium is attained rapidly at 50°C and isopropyl alcohol is removed from the hydrolysis mixture. Similarly, the weak sulfuric acid process minimizes the reconcentration of the acid and its associated corrosion and pollution problems. 

If the paddle width is so small as to leave isolated, unagitated portions of aluminum chloride, it should be moved near the surface to disperse the ketone rapidly. If the ketone is not dispersed, condensation to dypnone occurs. Tars found in the stripping process are believed to originate from improper addition of the ketone to the aluminum chloride. 

The component with the lowest equilibrium constant is called the key component in the stripping process, because it yields the largest value of Vnjm- This largest value is the true minimum air flowrate, whereas the actual air flowrate should be selected at 1.20 to 2.0 times the minimum. This becomes a balance between fewer theoretical stages at actual air flowrate, yet requires a larger diameter column to carry out the operation. 

In both cases, the extraction process includes washing (scrubbing) of the extract, a stage that is not shown separately. The organic phase that results from the stripping process is returned to the beginning of the extraction process for reuse as an extractant. 

TBP is less soluble and less dangerous but is more problematic due to its relatively high density. This can lead to poor stratification, especially during the stripping process. Hence, insufficient separation of the strip solution from the extractant can lead to additional contamination, by phosphorous, of the final products [458,462]. 

Two types of compounds, crystalline and amorphous, can be precipitated from tantalum or niobium solutions by an initial ammonia solution containing ammonium ions, with an interface at about pH = 10. Such solutions are used for the stripping of tantalum or niobium from TBP extracts. In the case of pure fluorotantalic or fluoroniobic acids that result from the stripping process with water, the interface occurs at a lower pH level. 

Draw an EQCM (mass-potential) profile for a metal deposition-stripping process during a cycling voltammetric scanning. 

In the discussion of the internal energy U of an ion formed in an ideal stripping process (Equation 13) the quantization of U was not considered. With increasing energy E of the incident ion, the production XH + can be... 

Figure 37.1. Continuous Vapor Stripped Process for the Rh Catalyzed Carbonylation of MeOH in the absence of Mel.

Ammonia stripping also removes cyanide, phenols, and other VOCs typically found in cokemaking wastewater. Phenols may also be removed by conversion into nonodorous compounds or into crude phenol or sodium phenolate by either biological means (phenol concentration <25 mg/L) or by physical processes.21 However, the Koppers dephenolization process is considered to be quite effective as it lowers the phenol content by 80 to 90% in ammonia still wastes. In this process a stream stripping process followed by mixing in a solution of caustic soda results in renewal of pure phenol with the flue gas.8... 

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