Vertical heaters

Vei tical cylindrical helical coil heaters are hybrid designs that are classified as vertical heaters, but their in-tube characteristics are like those of horizontal heaters. There is no convection section. In addition to the advantages of simple vertical cylindrical heaters, the helical coil heaters are easy to drain. They are limited to smaU-duty applications 5 to 21 Gl/h (5 to 20 10 Btu/h). 

Figure 10-1H. Fixed tubesheet, single-tube pass vertical heater or reboiler. (Used by permission Engineers Fabricators, Inc., Houston.)...

Bernath (1960) also studied the orientation effect on the CHF and found that the critical flux from a vertical heater is only about 75% of that of a horizontal heater under the same conditions. Further discussion of the latter effect is given in the section on the related effect of acceleration. 

Kirby, G. J., R. Staniforth, and J. H. Kinneir, 1965, A Visual Study of Forced Convection Boiling Part I, Results fora Flat Vertical Heater, UK Rep. AEEW-R-281, UK AEEW, Winfrith, England. (5) Kirillov, P. L., 1968, A Generalized Functional Relationship between the CHF and Pressure in the Boiling of Metals in Large Quantities, Transl. Atomic Energy 24 143. (2)... 

Vertical treaters have a much lower volume-to-throughput ratio than gun barrels. As a result, more complete treatment is necessary in a shorter time. Solids control is as important as interface control, just as with the horizontal treater. Figure 5 illustrates a schematic of a vertical heater treater that also employs a dual-polarity electrostatic grid to effect more efficient coalescence and thereby better oil-water separation. 

In the method of Belscher [1] iron globules are formed at the maximum possible Fe(CO)5 concentration in the decomposition zone. The apparatus of Fig. 339 is used. The air is flushed out with a moderately fast stream of N g introduced via the inlet tube to a. Then the liquid carbonyl compound is vaporized at a rate of 30 ml./hr. and the vapor fed into the decomposition chamber, which is heated to 200-600°C (depending on the reaction conditions). At this point the Ng flow is either reduced or shut off completely. The tubing from the distillation flask to the decomposition tube (which is surrounded by a vertical heater) must be well insulated or maintained at about 110°C by means of a small electric coil or tape in order to avoid decomposition of the iron carbonyl. The first crop of product does not have the desired properties. A uniform powder consisting of microscopic globules is obtained only after a certain induction period. 

Liquid helium can be regarded as an ordinary liquid however, its physical properties are modified somewhat compared to other liquids. The superheat data of Karagounis P ] correspond to reduced values larger than 1.5 ATp/Tc, whereas results from a vertical heater [- ] obtained at a very low power level, are small, as to be expected. In spite of the low temperature, there are no drastic deviations from thermodynamic similitude in the range 0.6 < T/Tc < 1, where equation (1) permits reasonable superheat estimates. 

The primary separator may also be known as a heater/treater tank. Heater/treater tanks are usually vertical tanks but some are horizontal. In a vertical heater/treater, the produced fluids flow into the top of the heated tank where they fall to the bottom and are circulated through varies baffles or other features in tank. The gas generally separates from the mixture and is taken off the top of the tank. The water in oil emulsion is then mechanically mixed and some separation occurs. An oil take-off value is usually located in the upper half of the tank that allows any free oil to be drained off. A drain in the bottom of the tank also will allow any free water to be taken off as well. 

Because gunbarrels tend to be of larger diameter than vertical heater-treaters, many have elaborate spreader systems that attempt to create uniform (i.e., plug) upward flow of the emulsion to take maximum advantage of the entire cross section. Spreader design is important to minimize the amount of short-circuiting in larger tanks. 

Gunbarrels are most often used in older, low-flow-rate, onshore facilities. In recent times, vertical heater-treaters have become so inexpensive that they have replaced gunbarrels in single-well... 

The most commonly used single-well treater is the vertical heater-treater, which is shown in Figure 1.7. The vertical heater-treater consists of four major sections gas separation, FWKO, heating and water-wash, and coalescing-settling sections. Incoming fluid enters the top of the treater into a gas separation section, where gas separates from the liquid and leaves through the gas line. Care must be exercised to size this section so that it has adequate dimensions to separate the gas from the inlet flow. If the treater is located downstream of a separator, the gas separation section can be very small. The gas separation section should have an inlet diverter and a mist extractor. 

FIGURE 1.7. Simplified schematic of a vertical heater-treater. 

As shown in Figure 1.14, a vane-type mist extractor removes the hq-uid mist before the gas leaves the treater. The gas liberated when crude oil is heated may create a problem in the treater if it is not adequately designed. In vertical heater-treaters the gas rises through the coalescing section. If a great deal of gas is liberated, it can create enough turbulence and disturbance to inhibit coalescence. Equally important is the fact that small gas bubbles have an attraction for surface-active material and hence water droplets. Thus, they tend to keep... 

Standard vertical heater-treaters are available in 20- and 27-ft (6.1 and 8.2 m) heights. These heights provide sufficient static liquid head so as to prevent vaporization of the oil. The detailed design of the treater, including the design of internals (many features of which are patented), should be the responsibility of the equipment supplier. 

FIGURE 1.15. Vertical heater-treater fitted with excelsior, between the baffles, which aids in coalescence of water droplets. 

Design Procedure for Vertical Heater-Treaters and Gunbarrels (Wash Tanks with Internal/External Gas Boot)... 

FIGURE 1.45. Typical vendor supplied vertical heater-treater capacity table. 

Figure 1.44 provides standard dimensions, pressure ratings, and fire-box ratings for vertical and horizontal heater-treaters. Figure 1.45 is a typical horizontal heater-treater table supplied by an equipment manufacturer. Figure 1.46 is a typical vertical heater-treater capacity table supplied by an equipment manufacturer. 

For testing the scaling laws, a two-phase natural circulation loop as shown in Fig. 11 was constructed. The loop was made of 50 mm NB (2 Sch 80) pipes except for the separator which is 150 mm NB (6 Sch 120) pipe. The separated steam is condensed and the condensate is returned to the separator. The vertical heater is direct electrically heated with a high current source. The loop was extensively instrumented to measure temperature, pressure, differential pressure, level and flow rate. Further details of the loop are available in Naveen et al. (2000). Prior to the actual experiments, pressure drop across one pipe segment was measured under forced flow conditions. This gave the following equation for the friction factor... 

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