Caustic scrubbing

Decomposition by Caustic Scrubbing. The waste gas stream is led through packed towers where a sodium hydroxide solution is introduced at the top of the towers. Venturi scmbbers can also be used. Makeup sodium hydroxide is added under pH control (32). 

Multiple-effect evaporators HciS, other odors Caustic scrubbing and thermal... 

Citrate process Copper oxide adsorption Caustic scrubbing... 

Mixing Valve This type of mixing device is normally a manually operated globe valve operated at 20 to 350 kPa pressure drop. Common use of this device in refinery operations is for water and crude oil mixing before a desalter and in caustic scrubbing operations. 

Recycle traditionally involves caustic scrubbing the gaseous HBr from bromination reactions (eqn. 3). The resulting sodium bromide solution is then treated with chlorine gas to generate bromine (eqn. 4). 

Caustic coupling process, 10 356-357 Caustic flooding, 15 629-630 Caustic fusion, of zircon, 26 628 Causticiation, 15 63 in Bayer process, 2 352 slaked lime in, 15 45, 63 Caustic scrubbing, phosgene decomposition by, 15 807... 

Generally, although not exclusively, a scrubber with a recycle loop of the caustic scrubbing liquor is used cases of once-through scrubbing liquor operation do exist. The scrubber may be operated in batch, semi-batch or continuous mode with respect to the liquid. Process hazards exist in batch and continuous mode, the most significant of which is over-chlorination. Batch-wise operations leads to periodic high loads on the hypochlorite destruction unit. In order to even out these loads, and improve the process safety, a study of alternative treatment options has been undertaken. 

The process concept is shown in Fig. 26.7 where the recycle loop of the caustic scrubbing liquor passes through a fixed-bed reactor and then through the normal cooler. The blow-down of spent caustic and make-up with fresh caustic can be carried on in the same fashion as without the in-loop hypochlorite decomposition. Consideration of the optimum locations for removal and addition may, however, be slightly different. 

The dinitro product is then cooled and filtered (the spent acid hquor is recoverable), the cake is washed with water, and the resulting washwater is sent to the wastewater treatment plant. The dinitro compound is then dissolved in an appropriate solvent and added to the amination reactor with water and soda ash. An amine is then reacted with the dinitro compound. The crude product is passed through a filter press and decanter and finally vacuum distilled. The saltwater layer from the decanter is discharged for treatment. The solvent fraction can be recycled to the reactor, and vacuum exhausts are caustic scrubbed. Still bottoms are generally incinerated. 

The caustic scrubbing part of the unit is very important in the pre-... 

In the process (Fig. 1), anhydrous hydrogen fluoride and carbon tetrachloride (or chloroform) are bubbled through molten antimony pentachloride catalyst in a steam-jacketed atmospheric pressure reactor at 65 to 95°C. The gaseous mixture of fluorocarbon and unreacted chlorocarbon is distilled to separate and recycle the chlorocarbon to the reaction. Waste hydrogen chloride is recycled by use of water absorption and the last traces of hydrogen chloride and chlorine are removed in a caustic scrubbing tower. 

The H2S formed in the hydro-desulphurisation process can be removed from the product stream in a variety of ways. Commonly used methods are chemical reaction with, for example, zinc oxide or iron oxide, caustic scrubbing and absorption processes. For the H2S decomposition processes treated in this chapter, only the absorption/desorption methods are of importance. Most used are absorber/stripper combination units with an alkanolamine as absorbing compound [2],... 

Sodium sulfide (Na2S) and sodium hydrosulfide, sometimes referred to as sodium sulfhy-drate (NaHS), share the same derivation caustic soda and H2S. Earlier processes, based on reduction of salt cake with coal, have largely been supplanted. In 2000, the U.S. installed capacity for NaHS was 184,000 tons/year. Additionally, there are more than 260,000 tons/year of lower-purity, lower-strength material recovered as byproduct from natural gas and small refinery operations.11 The source of H2S used in the manufacture of NaHS is essentially all byproduct. Controlled caustic scrubbing of H2S forms a solution of NaHS ... 

Kraft pulp mills Digesters batch and continuous Multiple-effect evaporators Recovery furnace Weak and strong black-liquor oxidation Smelt tanks Lime kiln Mercaptans, methanol (odors) H2S, other odors H2S, mercaptans, organic sulfides, and disulfides h2s Particulates (mist or dust) Particulates (dust), H2S Condensers and use of lime kiln, boiler, or furnaces as afterburners Caustic scrubbing and thermal oxidation of noncondensables Proper combustion controls for fluctuating load and unrestricted primary and secondary air flow to furnace and dry-bottom electrostatic precipitator noncontact evaporator Packed tower and cyclone Demisters, venturi, packed tower, or impingement-type scrubbers Venturi scrubbers... 

After compression (part 9X caustic scrubbing and drying, these light effluents enter the cold section of the unit, which can be designed in various ways, and which perfonns the following separations ... 

A condensed version of the ERDL alkylation pilot plant flow plan is shown in Figure 4. Olefin and isobutane feed streams are separately pumped to the unit from large feed storage vessels with Lapp Pulsafeeder diaphragm pumps and metered with turbine flow meters. The streams are then combined, caustic scrubbed, water washed and dried with molecular sieves before being sent to the reactor. The combined feed stream is then injected into the acid-hydrocarbon emulsion in the stirred reactor vessel. In order to maintain a constant temperature environment both reactor and settler are coolant jacketed. 

After reaction, the acid-hydrocarbon emulsion passes from the reactor to a baffled settler where a phase separation takes place and settled acid is pumped back to the reactor. The settled hydrocarbon phase is caustic scrubbed to remove any entrained acid and sent either to a material balance accumulator or to a product accumulation system. 

In a high containment plant, the release of fuel solution would probably be below current detection limits. However, if minimal off-gas treatment is applied (i.e. caustic scrubbing and filtration is omitted) then there would be potential for the release of fine droplets of fuel solution. The release fractions of volatile radionuclides will depend on the type of off-gas treatment process used. An indication of the activity release for a 50 kg dissolution of 1000 MWd/t fuel, involving the use of different off-gas treatment system (consider, scrubber), is presented in Table 12.7 (after McMahon et al., 1993). 

Numerous freezeout collections were made and analyzed. The air was drawn through a semicarbazide column and a caustic scrubbing column. The stream was then split one half passed through an irradiated flask and then into a series of traps, and the other half passed through a dark flask on its way to the traps. By examining... 

As seen from the equation, two moles of NO are generated for every mole of Co(N03)2 decomposed. Caustic scrubbing or catalytic reduction is most commonly used in commercial catalyst production for NO c removal. 

Naphthenic Acids. Naphthenic acids are cycloparaffinic organic acids and usually are monocarboxylic. These acids occur in crude oils and normally are recovered with the straight run gasoline and distillate oil fractions in a topping unit. If these fractions are caustic scrubbed, the naphthenic acids are recovered as the sodium naphthenates (5). 

Caustic scrubbers use a solution of dilute NaOH to remove mercap-tans and other sulfur compounds from gasoline streams. Feed is added to the bottom of the scrubber and makes contact with the caustic solution. The caustic-scrubbed product goes overhead. Spent caustic (mercaptan-... 

Condensers and use of lime kiln, boiler, or furnaces as afterburners Caustic scrubbing and thermal oxidation of noncondensables Proper combustion controls for fluctuating load and unrestricted primary and secondary air flow to furnace and dry-bottom electrostatic precipitator noncontact evaporator Packed tower and cyclone... 

The possibility of reaction of wash chemicals with deposits in the column should be considered. The route of venting or disposing of any hazardous reaction products must be adequately planned. In one incident (7), hydrogen sulfide was liberated to the atmosphere following reaction of an acid used for washing with deposits in a caustic scrubbing system. 

They stressed further that nitrate solutions, acrolein, caustic scrubbing, formaldehyde, and amine-aldehyde condensates are best applied as scavengers (for sweetening purposes) in produced oil, water, and gas (Sitz et al. 2003). 

Fig. 2.8. Zirconium Chloride Plant. 1, feed hopper 2, star valve feeder 3, ball valve 4, silica brick 5, steel shell 6, insulating brick 7, clean out 8, water-cooled copper electrode connector 9, graphite electrode and nipple 16, chlorine inlet pipe 11, nickel cross-over pipe 12, primary condenser 13, condenser jacket 14, ba 3e 15, discharge valve 16, air heater 17, blower 18, cyclone-type aftercondenser 19, water scrubbing tower 20, caustic scrubbing tower 21, exit gas outlet to stack 22, caustic circulating pump 23, waste water inlet 24, caustic bleed line (Stephens, W. W. and Gilbert, H. L.

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