Steam barometric condensers

Odors Air blowing, barometric condensers, drains, process vessels, steam... 

Vacuum Distillation - Heavier fractions from the atmospheric distillation unit that cannot be distilled without cracking under its pressure and temperature conditions are vacuum distilled. Vacuum distillation is simply the distillation of petroleum fractions at a very low pressure (0.2 to 0.7 psia) to increase volatilization and separation. In most systems, the vacuum inside the fractionator is maintained with steam ejectors and vacuum pumps, barometric condensers, or surface condensers. 

Figures 6-5 and 6-6 illustrate two-stage ejector installations with barometric and surface t) pe inter-after condensers respectively. The discharge of the steam non-condensables from the second stage jet of Figure 6-5 is exhausted to the atmosphere, while in Figure 6-6 the steam is condensed in the aftercondenser and, essentially, only non-condensables leave the ent of the aftercondenser. Figure 6-7A indicates a diagram of a three-stage barometric type installation.

A barometric condenser is to condense 8,500 pounds per hour of steam at 3.5 in. Hg abs using 87°F water. The non-condensables are 43 pounds/hr. Note that the noncondensables are less than one percent of the steam. 

Installation arrangements, 351 Pump-down time, 380 Selection procedure, 374 Specification form, 377 Specifications, 373 Steam jet comparison, 356 Types of loads, 359 Ejectors, 346 Applications, 353 Barometric condenser, 249, 376 Booster, 370 Calculations Actual air capacity, 362 Air equivalent, 360... 

Many refineries now use vacuum pumps and surface condensers in place of barometric condensers to eliminate generation of the wastewater stream and reduce energy consumption. Reboiled side-stripping towers rather than open steam stripping can also be utilized on the atmospheric tower to reduce the quantity of sour-water condensate. 

At a geothermal energy source, dry steam at 700 kPa and 170°C is available at a mass flow rate of lOOkg/sec. A barometric condenser at lOkPa is used to decrease the turbine exhaust temperature. Find (a) the power produced by the geothermal power plant as shown in Fig. 2.22a. (b) What is the power produced without the barometric condenser ... 

At a geothermal energy source, a mixture of 80% steam and 20% water at 140°C is available at a mass flow rate of Ikg/sec. A barometric condenser... 

Barometric condenser systems can be a major source of contamination in plant effluents and can cause a particularly difficult problem by producing a high-volume, dilute waste stream [8]. Water reduction can be achieved by replacing barometric condensers with surface condensers. Vacuum pumps can replace steam jet eductors. Reboilers can be used instead of live steam reactor and floor washwater, surface runoff, scrubber effluents, and vacuum seal water can be reused. 

The original steam condensers were barometric condensers, which were used to increase the efficiency of the steam-driven reciprocating beam engines by a factor of 10. The barometric condenser was invented by James Watt (the steam engine was invented by Thomas Newcomen). Exhaust steam is mixed directly with cold water. As this creates a vacuum, the barometric condenser must be elevated about 30 ft above grade. The mixed condensate and cooling water drains through a pipe called a barometric leg—hence the name barometric condenser. 

The surface condenser is an improvement on the barometric condenser, because it permits recovery of clean steam condensate. Other than this factor, the old-fashioned barometric condenser is more efficient than the more modern surface condenser. 

Steam jets have been around for a long time. They have just as ancient an origin as do steam-driven reciprocating pumps. They were used on early steam engines to pull a vacuum on the now-archaic barometric condenser. More recently, they were used to develop vacuums in such services as... 

All this wasted a tremendous amount of coal. Actually, only 1 to 2 percent of the energy of the coal was converted into useful work. Quite suddenly, the steam engine was revolutionized. Its efficiency was increased by a factor of 10. This was all due to the innovations of James Watt, who invented the external barometric condenser, in the late 1760s. 

Rather than cooling and condensing the steam in the cylinder, the steam was exhausted to an external condenser. In this external condenser, the exhaust steam was efficiently contacted with the cold water. This external or barometric condenser rather looks and performs like the deaerator we discussed in Chap. 15. The external condenser obviously achieved Mr. Watt s original objective. He could condense the steam without cooling the cylinder. But the barometric external condenser was found to have an even more important attribute. Let me explain. 

Figure 18.1 Barometric condenser improved efficiency of the legendary beam steam engine.

It is easy to see how the barometric condenser could condense the exhaust steam more efficiently than periodically squirting water into... 

There is another problem with the barometric condenser that did not become apparent at first. When the British Navy decided to convert from sail to steam, this problem was immediately obvious. While steam can be generated from seawater, it is far better to use freshwater, especially if one wishes to generate high-temperature, high-pressure steam. And as freshwater supplies are limited at sea, it would be great if the condensed steam could be recycled to the boilers. But the cooling-water supply to the barometric condensers was naturally seawater which mixed with the steam condensate. 

The solution is straightforward. Do not condense the steam by direct contact with cold water, as is done in the barometric condenser. Condense the steam by indirect contact, with the cold surface of the tubes in a shell-and-tube condenser. Hence the name surface condenser, a sketch of which is shown in Fig. 18.2. Compare Fig. 18.1 with the surface condenser. Is there really much difference Other than recovering clean steam condensate for reuse, there is no difference at all. I last used a surface condenser in 1976, on a sulfuric acid plant reactor feed gas boost blower, and it worked just fine. 

The vapors leaving the primary barometric condenser proceed to a steam ejector that is followed by another barometric. Pressures at the tops of the towers are maintained at 50mmHg absolute. Pressure drop is 2mmHg per tray. Bottom temperatures of the three towers are 450, 500, and 540°F, respectively. Tower overhead temperatures are 200°F. Pitch and roan go to storage at 350°F and the other products at 125°F. The steam generated in the pitch and rosin coolers is at 20 psig. Process steam is at 150 psig. 

Uncondensed vapors are removed at the top of the column with a one-stage steam jet ejector equipped with a barometric condenser. 

In a four-effect evaporator steam is put into the first effect, where an effect relates to vapor flow, and the heat from that steam is used four times before condensation occurs in a barometric condenser. In theory, a four-effect evaporator will remove four liters of water per kilogram of steam usage, but in actual practice that water removal is about 3.4 1 per kg of steam-Heat losses and the change in the heat of vaporization with temperature account for the difference. 

An evaporator with a forced circulation of the liquid and a barometric condensation is shown in Fig. 106. Here, A is the heating element with nickel tubes, provided with steam supply connections and outlets for the condensate and noncondensable gases. The heating element projects about one half of its length into the body of the evaporator C, which is connected at the lower end by a wide pipe to the pump D. Fresh caustic solution, preheated in the heat... 

Uncondcnsed vapour from the first tower is led to the bottom part of the second column which is scrubbed with the condensate obtained from the heating steam which condenses in the distillation equipment. The remaining vapour then leaves the second column and is led to a barometric condenser of standard design connected to a vacuum pump, which maintains a reduced pressure of 110 to 140 mm Hg in the whole distillation equipment and 40 to 60 mm Hg in the condensation. The distillation yield reaches 90 to 92 per cent. A flow sheet is shown in Fig. 140. 

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