Crude column

Process feed-stream heaters such as the feed heaters for refinery crude columns (pipe stills) in which up to 60 per cent of the feed may be vaporised. 

Both the failure of the isolation valves to hold and the difficulty in draining the system were due to solid build up in the circuit. In the previous two-year period, the refinery had changed its crude feedstock resulting in operating difficulties on the unit desalter. Carryover of salts led to accelerated corrosion in the crude column and associated piping circuits. 

Corrosion products plugged the lines making it difficult to operate the stripper. Ultimately, the stripper operation was discontinued while the crude column remained in operation. This should have signaled the need for a major turnaround. Management did not have the perspective to analyze and prohe the reasons behind these operating problems. 

To a flask containing 2.0 gm (0.01 mole) of cupric acetate in 25 ml (0.38 mole) of dimethylamine in 100 ml of benzene at 5°C are added dropwise simultaneously a solution of 5.1 gm (0.05 mole) of phenylacetylene in 100 ml of benzene over 30 min and a stream of oxygen (1.0 ft3/hr). The oxygen stream is added for 30 min more after the phenylacetylene addition has been completed. The copper ions are precipitated by adding 100 ml of ice water. The organic layer is separated, dried, and concentrated under reduced pressure. A gas chromatograph of the crude (column 10 ft x in. 410 gum rubber) showed two peaks N, A-dimethylamino-2-phenylacetylene and 1,4-diphenylbutadiyne. The ynamine was obtained in 40 % yield as determined by reaction of the crude... 

Fig. 12. (a) Schematic diagram of cmde unit showing five hot streams leaving the crude column, and (b) temperature enthalpy diagram for the streams in where A represents the kerosene pumparound B, the gas oil product C, the residuum D, the overhead reflux and E, the cmde. The dashed line is the... 

Crude column side stripper overhead dew point, 34.7 psia, 313°F... 

Use type 316L (UNS S31603) SS (2.5% Mo minimum) cladding In vacuum column only when neutralization number exceeds 0.5 mg KQH/gm, Use type 316L SS (2,5% Mo minimum) In the crude column as well when the neutralization number exceeds 2,0 mg KQH/gm,... 

Description Acetone and excess phenol are reacted by condensation in an ion exchange resin-catalyzed reactor system (1) to produce p,p BPA, water and various byproducts. The crude distillation column (2) removes water and unreacted acetone from the reactor effluent. Acetone and lights are adsorbed into phenol in the lights adsorber (3) to produce a recycle acetone stream. The bottoms of the crude column is sent to the crystallization feed pre-concentrator (4), which distills phenol and concentrates BPA to a level suitable for crystallization. 

In the usual two-column scheme, the primary column depends on recovered heat for vapor formation a few refiners use a fired heater reboiler. The main crude column runs at low pressure compared to the single-column situation. The main column in two-column systems is often called the secondary column or the atmospheric column. ... 

When volatiles and water are removed in a flash vessel rather than by a primary column, it is sometimes expedient to direct the flash vessel overhead stream into the crude column. Unfortunately, the flashed stream is relatively cold and may contain color bodies from entrained crude residue. These characteristics favor the use of a primary distilling column rather than a flash vessel. 

Fig. 6 Typical crude column cuts, molal distribution.

Rectification of reformer feed can be improved by providing more internal reflux for the upper trays of the crude column, perhaps by using less pumparound heat removal above the jet fuel draw point. 

The upper section of the cracking plant fractionator is very similar to the crude column arrangements previously discussed. 

These columns in principle are like crude columns, taking various lubricating oil stocks as side draws and using pumparound and water or air top condensing systems. The more recent installations use packing for internal condensing and rectification, for low pressure drop, and use in the order of 50 to lOOTorr as top column pressures. Vacuum systems are similar to those... 

Side coolers or condensers are commonly used in multi-product columns to prevent excessive variations in the vapor and liquid flow profiles along the column. The multi-product column described in Section 9.2 had, for simplicity, only one condenser and a reboiler. If the feed in this column is introduced at its lower part, the vapor and liquid rates would continuously increase above the feed to the top of the column. A similar situation would exist in crude columns if no side coolers were used. 

A water-containing stream that found its way to the column (a typical example is water discharged from the desalter safety valve and ends up in a refinery crude column). 

A common troublespot in refinery crude units is the desalter relief valve, which often relieves into the crude column. Lifting of this relief valve has caused pressure surges. Guidelines 4 and 5 are important with regard to the location of this valve (296). It is best to have this relief valve discharge elsewhere. 

Refinery Asphaltic crude Column effidenqy severely drof ped fol-... 

What was wrong with the bottom s stripping trays Possibly, over the last few years they had been damaged. Perhaps water had entered the crude column on start-up and blown the tray decks out As I could find no measurable AP across the trays, I was fairly certain that the trays were no longer intact. 

I once tried to increase the flow of jet fuel from a crude distillation column by opening the draw-off flownozzle exit loss—or cavitation limits. To prove my point, I increased the level of liquid in the draw-off sump from 2 to 4 ft. Since flow is proportional to velocity and head loss is proportional to (velocity) the flow of jet fuel increased from 1000 to 1414 GPM. That is, the flow increased in proportion to the square root of the increase of liquid level in the sump. But the sump was only 4 ft high, and I needed to increase jet fuel flow even further. So 1 raised the pressure in the crude column from 10 to 14 psig. This increased the pressure in the draw-off sump by 4 psi. 

Transfer piping from oil refinery crude columns... 

For simulation purpose, we represent the furnace as a simple heater with a variable duty to match the overflash specification. There are many detailed models for the fired heaters in process simulators. Using these fired heater models can be sophisticated and is not the focus of this text. We will, however, model the crude column rigorously and include all side operations. 

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