Scrub solutions

Fieser s solution An aqueous alkaline solution of sodium anthraquinone -sulphonale (silver salt) reduced with sodium dithionite, Na2S204, and used as a scrubbing solution for partially removing O2 from, e.g., N2. 

Implement pH monitoring to determine useful life of scrubbing solution... 

In many cases, water is a poor scrubbing solvent. Sulfur dioxide, for example, is only slightly soluble in water, so a scrubber of very large liquid capacity would be required. SO2 is readily soluble in an alkaline solution, so scrubbing solutions containing ammonia or amines are used in commercial applications. 

These scrubbers have had limited use as part of flue gas desulfurization (FGD) systems, but the scrubbing solution flow rate must be carefully controlled to avoid flooding. When absorption is used for VOC control, packed towers are usually more cost effective than impingement plate towers (discussed later). 

Corti and Manfrida [2] have also done detailed calculations of the performance of plant A2. They drew attention to the need to optimise the amines blend (including species such as di-ethanolamine and mono-ethanolamine) in the absorption process, if a removal efficiency of 80% is to be achieved and in order to reduce the heat required for regenerating the scrubbing solution. Their initial estimates of the penalty on efficiency are comparable to those of Chiesa and Consonni (about 6% compared with the basic CCGT plant) but they emphasise that recirculation of water from... 

Experiments were performed in a packed column with 1000 mm in length and 18 mm in diameter. The absorber was operated with a continuous influent gas feed rate of 0.2L/min from fhe bottom and a continuous scrubbing solution fed at a superficial flow rate of 13 m /m. hr at the top, as described in [8]... 

Dual Alkali A flue-gas desulfurization process. The sulfur dioxide is absorbed in aqueous sodium hydroxide and partially oxidized, and this liquor is then treated with calcium hydroxide to regenerate the scrubbing solution and precipitate calcium sulfate. Developed by Combustion Equipment Associates and Arthur D. Little. 

Thus a spent scrubbing solution is obtained that contains equimolar quantities of NaOCl and NaCl. The chlorine-containing vent streams may contain also and variously C02, HC1 and other components naturally occurring in atmospheric streams. Clearly the C02 and HC1 have the potential to reduce the capacity of the caustic stream for chlorine removal. 

Solids that settle from the scrubbing solution will periodically be drained into drums and sent to the TRBPs for processing as site-generated waste. 

Finding DII FEK-8. While no agent was detected in the scrubbing solutions and scrubber filters, the ability of the GPCR process to destroy HD in mortars and neat GB could not be confirmed because sampling and analysis problems hampered the gathering of gas-phase data. 

Data obtained in scrubbing tests can be presented graphically, such as by plotting the concentration of metals in the organic phase against A/O ratio, salt concentration in the scrub solution, temperature, etc. Typical plots for the removal of nickel from cobalt in a DEHPA-containing solvent are shown in Figs. 7.3 and 7.4 [3]. 

Fig. 7.3 Effect of scrub solution composition on the removal of nickel from cobalt in a DEHPA-kerosene solvent.

The cascade is fed with an extract of the same composition as that resulting from the extraction shown in Table 8.5, with = 0.332 and Eg = 0.058. In four stages, using a concentrated solution of at 0 = 10, Eji = 0.350 and Eb = 0.00014, the purity of the product is increased from 85-99.96%. Note that the composition of the scrub solution is the same as... 

A number of processes can be considered double alkah processes, but most developmental work has emphasized sodium-based systems, which use lime for regeneration. This system pretreats the flue gas in a prescrubber to cool and humidify the gas and to reduce fly ash and chlorides. The gas passes through an absorption tower where SO2 is removed into a scrubbing solution, which is subsequently regenerated with lime or hmestone in a reaction tank. 

Cadmium may be measured by various instrumental analysis (see cadmium). Cyanide may be extracted by distilling an acidified solution of cadmium cyanide and then purging the liberated hydrogen cyanide with air, passing it into a scrubbing solution of caustic soda. Cyanide in the scrubbing solution is... 

Figure 1. Flow schematic of a spray-tower adsorber. The scrubbing solution is contacted with hot flue gas, collected in the bottom, and continuously recycled and contacted. Suspended solids and pH of liquid in the recycle loop of Plant D spray towers ranged from 5.2 to 8.7%, and from 5.2 to 6.80%, respectively.

Finally, corrosion of internal metal surfaces, constituents of the absorbing and water-conditioning agents, and condensation of vapor components further contribute to the concentrations of Cr and Mn, Ca and P, and Se and S in the scrubbing solution and lead to their enrichment in fine aerosol emissions. 

ClNOz, and C10N02. The air then passes into a second chamber with an alkaline scrubbing solution, which absorbs most of the Cl2 and some HOC1. The two solutions are analyzed for chloride ion by ion chromatography. Differences in the chloride ion concentrations in the acid compared to the alkaline solutions provide a measure of chlorine-containing inorganics other than HC1. 

Scrubbers. Mist chamber scrubbers have also been used for HN03. The airstream passes through a Teflon filter to remove particles and then encounters a mist of water that scrubs the HN03 out of the air. The nitrate concentration is measured in the aqueous scrubbing solution using ion chromatography (Talbot et al., 1990). 

Scrubbing solutions containing sodium (or other alkali metals) compounds have been extensively studied for removal of S02. Justification for the use of sodium compounds includes (a) complete solubility in water with no formation of scale and (b) simple reactions with S02 Na2C03 +... 

Solutions containing ammonium sulfate, with or without the addition of ammonium hydroxide, have been widely used. The ammonium system can operate effectively only within a pH range of 4.0 to 7.0. As the pH value increases above 7.0, progressively more gaseous ammonia is liberated and this reacts in the gaseous phase with water vapor and SO2 to produce a dense aerosol (white plume) which is difficult for scrubbers to remove. In an ammonia system, in order to regenerate the scrubbing solution, the ammonium bisulfite and sulfite mixture is heated... 

The second flowsheet was therefore implemented in 24 stages (Figure 3.13) (177). This time, the An(III) + Ln(III) product solution contained only 0.66% Sr and 1.31% Mo. However, the large amounts of oxalic acid (up to 0.4 M) introduced in the feed and scrubbing solutions to avoid Zr extraction led to partial precipitation of An(III) and Ln(III) oxalates in the low acidity conditions of the stripping section. 

Although promising, this system has not been further developed because of its sensitivity to pH variations and the need to buffer the feed (either via a front-end step where the feed acidity is reduced through denitration, or via the introduction of large amounts of carboxylic acid in the scrubbing solution). 

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