Acid carryover

In addition to using a phosphate buffer solution of pH 7, solutions of different pH values can often be evaluated. The use of pH 4 and pH 10 buffer solutions are typically requested. The use of pH 4 buffer simulates acid carryover into fuel from acid washing, acid extraction, or acid catalysis. The use of pH 10 buffer simulates caustic washing or caustic carryover from fuel sweetening and neutralization processes. 

Check pH of water bottoms. If <7, acid carryover and contamination may have occurred. 

Sulfuric acid alkylation units have excellent safety reports [18], The main concerns are the H2S04 and the large inventories of light hydrocarbons. The incidents that have been reported include emulsion-separation difficulties leading to acid carryover, acid runaway resulting in low-quality alkylate and requiring shut down of the olefin feed, or tight emulsion in the net effluent water wash with the consequence of carryover of the alkaline water into the separation section. 

Alkylation quality, 145-146 Alkylation, 136-155 process description, 136-140 acid carryover, 140-148 improving alkylate octane, 147-148 hydrofluoric acid alkylation, 148-155 troubleshooting problems, 154 sulfuric acid, 155... 

The acid recycle is warmer than the reactor effluent. This is an indication that esters are continuing to react in the acid settler. The resulting heat of reaction increases the temperature of the acid recycle, while the hydrocarbon reactor effluent remains cool. The reaction of acid esters in an isobutane deficient environment increases the rate of acid consumption and lowers acid strength. Reduced acid strength produces more esters to fuel the after-reaction in the acid settler. This self-escalating production of esters is an acid runaway situation and is indicative of a chemical acid carryover requiring increased acid circulation. A 15°F temperature difference between the acid recycle and hydrocarbon effluent is an indication of an incipient acid runaway situation a S F difference, while undesirable, is normal. 

But, Norm," Zip said, "I wasn t that worried about this acid carryover. This has happened before. We ve been running this unit for 30 years. The old 8-in line, why, it lasted for 30 years. It never blew out like this. Just cause of a little acid carryover. Norm, what are we going to do now "... 

The first step in CTO distillation is depitching. A relatively small distillation column is used as a pitch stripper. The vapor from the pitch stripper is fed directiy into the rosin column, where rosin and fatty acids are separated. Rosin is taken from the bottoms of the column and fatty acids as a sidestream near the top. Palmitic acid and light neutrals are removed in the rosin column as heads. The operation is designed to minimize holdup and product decomposition. Care is taken to prevent carryover of some of the heavier neutrals, such as the sterols, from the depitcher to the rosin column (24). 

Aikaiinity Bicarbonate (HCOs" ), carbonate (COs , and hydroxyl (OH ), expressed as CaCOs Foaming and carryover of solids with steam embrittlement of boiler steel bicarbonate and carbonate produce CO2 in steam, a source of corrosion Lime and lime-soda softening, acid treatment, hydrogen zeolite softening, demineralization, dealkalization by anion exchange, distillation, degasifying... 

Gas-liquid Mist Acid mist carryover chromic acid oil mists tar fog... 

These factors severely enhance the risks of condensate system corrosion by carbonic acid (resulting from a breakdown of the alkalinity in the boiler water and carbon dioxide [C02] carryover into the steam) and BW carryover. In addition, boiler operation is more difficult because the possible COC is severely limited, there-... 

Lack of dealkalization with high alkalinity MU water NOTE Anion dealkalizers do not use acid, but also do not reduce MU water TDS and introduce additional chlorides (risk of pitting). Excessive CR line corrosion BW carryover Low cycles of concentration higher operating costs... 

Process contamination. Sticky films (LP boilers) Varnish (HP boilers) Steam discoloration FW pH fluctuations Acid corrosion Stable foams leading to carryover... 

The carbon dioxide carryover dissolves in condensed steam, where it is partially hydrated to form carbonic acid (H2C03), as shown below. The increase in hydrogen ion concentration causes the pH to be depressed and generally results in a condensate with a pH of approximately 5.0 to 5.5. 

Sulfites are typically suitable for use in 900 psig boilers. If carryover of BW (containing sulfite) into a superheater occurs, however, then at very high temperatures the sulfite may break down to form acidic sulfur dioxide, which in turn forms sulfurous acid and reduces the pH of the condensate. 

Gas Gas-vapour Gas-liquid Gas-solid Gas-liquid-solid Mist Fume SO2 NOxI HCI CO hydrocarbons Acid mist carryover chromic acid oil mists tar fog Metal oxides, cement dust Paint spray... 

The carryover of caustic into a finished fuel blend usually has minimal effect alone on the corrosion of ferrous metals. However, in fuel systems containing a conventional tall oil dimer-trimer fatty acid or partially esterifled corrosion inhibitor, caustic can react with and negate the effect of the corrosion inhibitor. As a calcium or sodium salt, these inhibitors will no longer function effectively as an oil-soluble, fuel corrosion inhibitor. 

During the processing of fuels, acids such as sulfuric acid and hydrofluoric acid are used. Sulfuric acid can be used to polymerize fuel olefins and remove components from fuel such as mercaptans and thiophenes. Sulfuric and hydrofluoric acids are used in the alkylation process to produce high-octane, branched paraffins. Carryover of these acids into fuel can initiate ferrous metal corrosion. 

Also, caustic carryover from acid neutralization can occur, but is remote. What to Do ... 

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