Flue Gas Scrubber Solutions

In this reaction, diphenylcarbazide is oxidized to diphenylcarbazone, while at the same time chromium(VI) is reduced to chromium(III), which forms a chelate complex with diphenylcarbazide. Like the metal-PAR complexes, it is red-purple colored and thus may be photometrically detected at 520 nm. As already mentioned, chromate separation is performed by means of anion-exchange chromatography. The high selectivity of this technique is revealed in Figure 8.51, which shows the analysis of chromium(VI) in a flue gas scrubber solution. Despite high contents of chloride and sulfate, chromium(VI) can be determined in this sample without any interferences. 

Figure 8.51 Analysis of chromium(VI) in a flue gas scrubber solution. Separator column lon-Pac CS5A eluent 2 mmol/L pyridine-2,6-dicarboxylic acid + 2 mmol/L Na2HP04 +10 mmol/L Nal +50 mmol/L NH4OAC flow rate ...

Figure 10.119 Analysis of inorganic anions in volume 50 (iL sample flue gas scrubber solu-a flue gas scrubber solution. Separator column Son, 1 100 diluted peaks 1 lOmg/L fluoride lonPac AS4 eluent 2.2 mmol/L Na2C03 + 25 (1), 650 mg/L chloride (2), 1300 mg/L nitrate...

Today, the determination of sodium, potassium, and magnesium in flue gas scrubber solutions is carried out with a weak acid cation exchanger utilizing suppressed conductivity detection (Figure 10.120). However, ammonium present at low concentration cannot be determined in the same run under these... 

Thus, the retention difference between fluoride and chloride, which is less than 2 minutes under the same conditions on an AS4A column, may be expanded to more than 20 minutes with the CarboPac PAl. Figure 3-122 illustrates an example of the baseline-resolved separation of various monocarboxylic acids, which would elute as one peak close to the void volume when using an AS4A column. Monocarboxylic acids are relevant in many of today s analysis problems this procedure provides an elegant solution. Amidosulfonic acid, for example, is one of the many components in flue gas scrubber solutions from desulfurization devices, which require frequent analysis. 

Fig. 7-34. Analysis of chromium (VI) in a flue gas scrubber solution. — Separator column lonPac CS5 eluant 2 mmol/L pyridine-2,6-dicarboxylic acid + 2 mmol/L Na2HP04 + 10 mmol/L Nal + 50 mmol/L NH4OAC flow rate 1 mL/min detection photometry at 520 nm after reaction with 1,5-DPC reagent composition 2 mmol/L 1,5-diphenylcarbazide + 0.5 mol/L H2SO4 — methanol (90 10 v/v) reagent flow rate 0.5 mL/min injection 50 pL sample (1 10 diluted).

Fig. 9-63. Cation analysis in a flue gas scrubber solution. -Separator column lonPac CS12 eluant 20 mmol/L methanesulfonic acid flow rate 1 mL/min detection suppressed conductivity injection 25 pL flue gas scrubber solution.

More than 80% of all sodium chlorite produced is used for the generation of chlorine dioxide. Sodium chlorite is also used in disinfectant formulations and sterilization. Like chlorine dioxide, it must be registered with EPA under FIFRA for each specific application use as a disinfection. Sodium chlorite is used in other industrial settings in NO and SO combustion flue gas scrubber systems in the treatment and removal of toxic and odorous gases such as hydrogen sulfide and mercaptans and as a solution formulation to oxidize copper surfaces in multilayer circuit boards (Kaczur and Cawlfield 1993). 

Flue gas scrubbing also has high capital and operating costs associated with it, but also offers PM control. An additive-only solution is almost always the least expensive option when including both capital and operating expenses for SO, reduction depending on the feed sulfur. SO, reduction additives can also be effectively used in conjunction with one of the other solution options. For example, several refiners with FCC feed hydrotreaters use a SO, reduction additive to trim the SO, emissions to the required 25 ppm level rather than to hydrotreat the FCC feed more severely or to install a flue gas scrubber. The optimum choice for a given unit is often site specific. 

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). 

While the use of low-sulfur fuels is one mechanism to reduce sulfur dioxide emission, alternatively most approaches focus on scrubbing or ridding the emissions in smoke stacks of sulfur dioxide gas. A number of different types of scrubbers, i.e., sulfur dioxide removal systems, are available for industry. One system sprays the flue gas into a liquid solution of sodium hydroxide. The hydroxide combines with SO2 and O2 to form the corresponding sulfate which can be removed from the aqueous solution ... 

Wellman-Lord The most widely used regenerable flue-gas desulfurization process. The sulfur dioxide is absorbed in sodium sulfite solution in a wet spray scrubber, forming sodium bisulfite ... 

The gas stream leaving the dryer is treated in wet scrubbers, using a water-based sodium carbonate (Na2C03) solution to recover fine particulates that escape the dryer cyclone and remove most of the SOx from the flue gas. 

Recently, we returned to the Allen plant and sampled the flue gas using a four impinger train with a pre-scrubber of sodium carbonate to remove the acid gases, followed by three impingers charged with iodine monochloride solution. Preliminary results show that mercury quantities detected were of the expected magnitude based on mercury concentrations in the coal which we had measured previously. This technique will be used for the mercury balance at the next in-plant sampling. 

Flue-gas from boilers fired with liquid or solid fuels contains fly-ash and gaseous contaminants such as CO, NOx, SO2, or volatile organic compounds (VOCs). Emission regulations require their removal, which is achieved by a sequence of after-treatment processes. The after-treatment usually comprises a filter to remove solid particulates operated at approximately 150 °C, a wet scrubber for the removal of SO2 with an alkaline solution operated at approximately 50 °C, and finally a selective catalytic reduction (SCR) unit, which converts NOx to N2 with the help of NH3 at approximately 370 °C (Fig. 15.1) [4]. During this process, the flue gas is cooled down and then heated up again, which requires additional heat transfer equipment, with its inherent energy losses. 

Multi ventuii off-gas scrubber for high efficient cleansing of contaminated flue gases stemming from thermal conversion of refuse and waste materials, containing the following advanced and innovative technical solutions ... 

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