Main Condenser

Del y for Dec y. Nuclear power plants generate radioactive xenon and krypton as products of the fission reactions. Although these products ate trapped inside the fuel elements, portions can leak out into the coolant (through fuel cladding defects) and can be released to the atmosphere with other gases through an air ejector at the main condenser. 

Figure 2.10 Wastage in a circumferential region where a 90 10 cupronickel main condenser tube passed through a baffle. In places, metal loss was greater than 25% of the nominal wall thickness.

Specimen Location Main condenser near inlet water box... 

A typical microbiological analysis in a troubled carbon-steel service water system is given in Table 6.2. Table 6.3 shows a similar analysis for a cupronickel utility main condenser that showed no significant corrosion associated with sulfate reducers. When biological counts of sulfate reducers in solid materials scraped from corroded surfaces are more than about 10, significant attack is possible. Counts above 10 are common only in severely attacked systems. 

TABLE 6.3 Typical Microbiological Analysis at Outlet A Main Condenser Suffering No Significant Corrosion by Sulfate-Reducing Bacteria ... 

After only 4 months of service, the main condenser at a large fossil utility began to perforate. Initial perforations were due to erosion-corrosion (see Case History 11.5). Small clumps of seed hairs entering the condenser after being blown into the cooling tower were caught on surfaces. The entrapped seed hairs acted as sieves, filtering out small silt and sand particles to form lumps of deposit (Fig. 6.24A and B). Immediately downstream from each deposit mound, an erosion-corrosion pit was found. 

Specimen Location Surface condenser tube, main condenser bundle... 

Six iron anodes are required for corrosion protection of each condenser, each weighing 13 kg. Every outflow chamber contains 14 titanium rod anodes, with a platinum coating 5 /tm thick and weighing 0.73 g. The mass loss rate for the anodes is 10 kg A a for Fe (see Table 7-1) and 10 mg A a for Pt (see Table 7-3). A protection current density of 0.1 A m is assumed for the coated condenser surfaces and 1 A m for the copper alloy tubes. This corresponds to a protection current of 27 A. An automatic potential-control transformer-rectifier with a capacity of 125 A/10 V is installed for each main condenser. Potential control and monitoring are provided by fixed zinc reference electrodes. Figure 21-2 shows the anode arrangement in the inlet chamber [9]. 

Where Water Hammer Occurs. Water hammer can occur in any water supply line, hot or cold. Its effects can be even more pronounced in heterogeneous or biphase systems. Biphase systems carry water in two states, as a liquid and as a gas. Such a condition exists in a steam system where condensate coexists with live or flash steam in heat exchangers, tracer lines, steam mains, condensate return lines and, in some cases, pump discharge lines. 

Water hammer can also occur in steam mains, condensate return lines, and heat exchange equipment where steam entrapment can take place (Fig. I). A coil constructed and installed as shown here, except with just a steam trap at the outlet, permits steam from the control valve to be directed through the center tube(s) first. Steam then gets into the return header before the top and bottom tubes are filled with steam. Consequently, these top and bottom tubes are fed with steam from both ends. Waves of condensate are moved toward each other from both ends, and steam can be trapped between the waves. 

In general, the number of boosters determines the operational flexibility of the unit with respect to the refrigeration load. A single booster unit operates continuously, regardless of load. A two booster unit can operate at 50% load by shutting off one unit at lower load levels it uses a pressure controller on the steam actuated by the condenser pressure. Because jets are not usually very flexible with respect to steam consumption and vacuum, load control may be in increments as compared to continuous variation. If a 100-ton unit is expected to operate an appreciable portion of the time at 25% of load, it may prove economical to install a four-booster unit and to operate only one for this period. Auxiliary ejectors remove uncondensed water vapor and air from the main condenser. 

Manually Controlled System A manually controlled system comprises one or more transformer-rectifiers each with its associated control panels which supply the d.c. to the various anodes installed in the water box spaces. Each transformer-rectifier is provided with its own control panel where each anode is provided with a fuse, shunt and variable resistor. These enable the current to each anode to be adjusted as required. Reference cells should be provided in order to monitor the cathodic protection system. In the case of a major power station, one transformer-rectifier and associated control panel should be provided for separate protection of screens, circulating water pumps and for each main condenser and associated equipment. 

Main blowdow n valve, see Valve, blowdown Main condenser, see Condenser, main Maintaining inhibitor levels and controlling ... 

Polyphenols are significant constituents in the IDF of the samples analyzed, accounting for 1.4% to 4.7% (average, 2.5%). PPs are therefore an important constituent of DF in fruits and vegetables they are mainly condensed tannins (proanthocyanidins) and hydrolyzable tannins. 

A wide variety of hyperbranched polymers have been described in the literature. Initially, these were mainly condensation polymers such as polyesters and polyethers since the required monomers were the most readily available. A number of hyperbranched polymers based on vinyl monomers have been described lately after the introduction of self-condensing vinyl polymerization. One structural variation which has been widely employed for hyperbranched... 

Steam in an ideal Rankine cycle flows at a mass rate of flow of 141bm/sec. It leaves the boiler at 1250 psia and 1000°F, and enters a turbine where it is expanded and then exhausted to the main condenser, which is operating at a pressure of 1 psia. The fluid leaves the condenser as a saturated liquid, where it is pumped by a pump back into the boiler. Determine for the cycle ... 

Region B A main condenser, a Roots pump with a bypass line, an intermediate condenser, and a gas ballast pump. 

The chief engineer of a West Texas process plant had decided to replace the main condenser. Colder weather always coincided with a vastly improved vacuum, in their vacuum tower. It seemed as if colder air to the condenser really helped. So the engineering concluded, that a bigger condenser would also help during warm weather. 

Trim Cotiler—This unit condenses the last remaining light-end vapors and cools the liquid to the ultimate storage temperature (often about 100 F 38 Cl hy using cooling water. This cooling usually is not conducted in the main condenser because it would reduce column pressure. 

These designs have provisions for the removal of noncondensable vapors and air, for the prevention of freezing during cold weather. Excessive buildup of noncondensable vapors in the main condenser would prevent effective condensation. Protection against ice formation is usually accomplished by warm air recirculation and/or fan control. Condensed steam from cooling coils flows by gravity to condensate receivers and is pumped back to the feedwater circuit by a condensate pump. 

Neon boils at a considerably lower temperature than nitrogen and usually collects in the dome of the main condenser as a noncondensable gas. It can be recovered by the addition of a side column. 

As the flow of NO2 increases, the blue glow fades to a dark end point corresponding to complete consumption of N and N02 . The main condensible product in the reaction between NO2 and active nitrogen is N2O and at the end point the yield of N2O per N atom consumed is approximately 26 There is general agreement that the reactions... 

These data, in conjunction with previous studies (12) showed that stable char contains mainly condensed aromatic structure with intermittent paraffinic groups. This structure is formed by successive dehydration, rearrangement, loss of carboxyl, carbonyl, and paraffinic groups, formation of free radicals, and condensation of the carbon skeleton to polycyclic aromatic structures. 

Boilers, steam mains, condensate lines, boiler feed water treatment plant, supply pumps ... 

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