at the top of the other after being heated by the superheated steam surrounding the tubes. The steam enters at the top over the tubes near one end, and, by means of a horizontal baffle, makes two passes over the tubes, leaving at the bottom. Exhaust steam from an adjacent plant supplies the steam used in these warmers, and superheater constructed similar to the oil heaters supplies the neces

FIGURE 10.-Crude oil and residuum flow sheet, Fuqua topping plant.

sary superheat. Manholes are provided in the water traps and oil warmers for inspection and cleaning. Plate XXII shows a general plan of the topping plant.

OPERATION.

Figure 10 shows the flow of the crude oil and residuum through the plant. The crude oil is pumped by four Worthington duplex pumps, 10 by 6 by 12 inches, through the jacketed line heat exchangers, being heated by the outgoing residuum contained in the 6-inch pipes. The 6-inch pipes enter the 12-inch pipes through stuffing boxes, and suitable swing connections are provided to permit free movement of both pipes. From the exchangers the crude

at about 165° F. (74° C.) enters the two horizontal cylindrical tanks in series; there a part of the water settles out and is drained to a sump hole. The oil then flows through the tubes of the oil warmers in parallel, receiving further heat from the superheated exhaust steam, and thence flows into the last water trap, where more of its water content is dropped; thence it passes to the header supplying the heaters. Oil enters the heaters at about 185° F. (85° C.) and passes through the tubes as previously described, being heated to the required temperature by the fire and gases from the combustion chambers. Each battery of eight heaters discharges into a 5-inch header which leads the hot oil to the separating chamber for that battery. The residual oil collecting at the bottom of this chamber gravitates through the 6-inch jacketed line heat exchanger to storage, being cooled by the incoming crude. This residuum is marketed as fuel oil, and its quality can be fixed by regulating the rate of fire and feed. Plate XXIII shows the vapor and distillate flow.

The vapors, separated from the hot oil as it percolates through the baffles, pass through 124-inch vapor take-off lines terminating in a single 12-inch vapor line supplying the condensers. Bottom steam superheated to about 310° F. (154.5° C.) is injected in the separators, where it assists in lifting the vapors from the oil. Two 10-inch vertical standpipes 20 feet high, joined at their top by two ells and a nipple, are placed in each vapor take-off line. A valve between them permits the operator to force the vapors over the top in traveling to the condensers. Heavy distillates mechanically entrained, which tend to discolor the product, are thus returned to the separators. This construction is shown in Plates XXI, B, (p. 50) and XXIV, A.

The vapors condensed and cooled by the cooling water surrounding the condenser pipes are collected as condensate by a 4-inch distillate line and pass to several small settling tanks, where the water contained is automatically separated and returned to the water hole supplying the cooling-water pumps.

RERUNNING PLANT.

From the settling tanks a part of the distillate is pumped to the rerunning plant for fractionation into different products, and the remainder flows by gravity to storage for shipment. Distillate enters the plant through a 4-inch line within the 12-inch vapor header, being heated by the vapors passing to the condensers. This line discharges into the first separator, and the distillate usually acquires enough heat from the exchanger to vaporize the first fraction. If this heat is insufficient, a by-pass connected to the first heater allows the distillate to pass through that heater. The residue from the

first separator is pumped through the second heater to the second separator, where a second vapor fraction is removed. The remaining distillate passes through the third heater to the third separator, where a final vapor cut is separated. The bottom distillate from this separator is cooled in a box condenser and gravitates to storage. The heaters are fired with oil or gas, and the construction of all apparatus in the rerunning plant is identical with that of the crude

set.

DISTILLATE SAMPLE.

The table shown below gives an average sample of distillate from the plant and the resulting fractionation accomplished in rerunning. Third fraction.

First-run distillate.

Gravity, 44.5° B. (0.804).
24 per cent of 60° B. (0.739).
8 per cent of 50° B. (0.779).
68 per cent of 38.3° B. (0.833).

First fraction.

Gravity, 56.5° B. (0.752).

80 per cent of 60.1° B. (0.738). 20 per cent of 38.1° B. (0.834).

Second fraction.

Gravity, 46.3° B. (0.795).
2 per cent of 60° B. (0.739).
64 per cent of 50° B. (0.779).
34 per cent of 38.2° B. (0.834).

Gravity, 42.4° B. (0.813).
18 per cent of 50° B. (0.779).
82 per cent of 40° B. (0.825).
Bottom distillate.

Gravity, 33.2° B. (0.858).
10 per cent of 40° B. (0.825).
90 per cent of 32.4° B. (0.862).

The results of a typical laboratory fractionation made by the refinery chemist of the first-run distillate having a gravity of 43.5° B. (specific gravity, 0.808) follow. The fractionation was made in a 2,000-c. c. flask, 1,250 c. c. of distillate being used, and each 2 per cent fraction being tested. The rate of distillation was two drops per second, while the condenser was maintained at a temperature of 70° F. (22.2° C.), and with a room temperature of 60.0° F. (15.6° C.).