Condensation Control Systems

As illustrated by the previous example, other factors than purely physical considerations play an important role in condensation control. The properties of air barriers or vapour retarders are not the only concerns in preventing condensation problems. Different condensation control strategies may be combined in order to create condensation control systems with a greater probability of effectiveness in building practice. 

Control of moisture access Eliminate air leakage Air barrier 

Control of moisture accumulation Raise temperature of condensing surface Insulation outside of condensing surface 

Removal of moisture Promote drying Vapour permeable layers 

Reduction of moisture load Limit construction moisture Initially dry materials 

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Column pressure control is frequently integrated with the condenser control system. This control is often regarded as the most important control in the column. It has been the author s experience that a column will not achieve stable operation imless steady pressure can be maintained. 

Table 4.5 lists measures to restrict the moisture load by proper building design and operation. The individual measures may be combined to create an effective condensation control system. This way the integral building envelope and even the building may be regarded as a protective system for moisture control. 

The sampling system consists of a condensate trap, flow-control system, and sample tank (Fig. 25-38). The analytical system consists of two major subsystems an oxidation system for the recovery and conditioning of the condensate-trap contents and an NMO analyzer. The NMO analyzer is a gas chromatograph with backflush capabihty for NMO analysis and is equipped with an oxidation catalyst, a reduction catalyst, and an FID. The system for the recovery and conditioning of the organics captured in the condensate trap consists of a heat source, an oxidation catalyst, a nondispersive infrared (NDIR) analyzer, and an intermediate collec tion vessel. 

The AVR may be designed for variable duty, for automatic control of the reactive power, to the required level through feedback control systems. The machines will now operate only as synchronous condensers without performing any mechanical duty. 

Control. It is necessary to have some over-surface and to have a proper baffling to allow for pressure control during process swings, variable leakage of inerts, etc. One designer adds 50% to the calculated length for the oversurface. The condenser must be considered part of the control system (similar to extra trays in a fractionator to allow for process swings not controlled by conventional instrumentation). 

Pressure can also be controlled by variable heat transfer coefficient in the condenser. In this type of control, the condenser must have excess surface. This excess surface becomes part of the control system. One example of this is a total condenser with the accumulator running full and the level up in the condenser. If the pressure is too high, the level is lowered to provide additional cooling, and vice versa. This works on the principle of a slow moving liquid film having poorer heat transfer than a condensing vapor film. Sometimes it is necessary to put a partially flooded condenser at a steep angle rather than horizontal for proper control response. 

Condensation scrubbing systems are a relatively new technology and are not yet generally commercially available. It may be argued that this is a pollution prevention type of technology since it replaces other approaches to controlling very fine PM, although the primary role is end-of-pipe treatment. 

Condensation is normally used for the recovery of organic compounds from process or tank vent gases or from releases during loading. Condensation is used to recover valuable compounds prior to incineration, or to reduce the organic load entering other control systems, such as adsorbers or absorbers. Adsorption and absorption processes benefit from low condenser outlet temperatures. 

From a hydrate melting standpoint it is possible in the winter time to have too cold a liquid temperature and thus plug the liquid outlet of the low temperature separator. It is easier for field personnel to understand and operate a line heater for hydrate control and a multistage flash or condensate stabilizer system to maximize liquids recovery. 

Condenser Controls. .Miscellaneous (Condensing System). Circulating Water. System. Condensate Sysrem. . Pumpa, Piping and Valves. .Low/Tnter. Press- Heater/Oeaerators 3350-3352. .Polishers/Chemical Addle Ion 3360-3399. .Miscellaneous (Condensate System) 3901-3999. Feedwater System 3501-3509. Heater Drain Systems 3520-3529. Entractlon Steam. Electrical. Auxiliary Systems. .Service Water (Open System)... 

I. Space Heaters. A resistive heating device installed in the motor to prevent condensation when the motor is not operating. This requires a special control system. 

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. 

These same diamine materials find further application in, for example, formulations for mussel and barnacle control in large once-through, condenser cooling systems, as corrosion inhibitors and biostats for hydrostatic testing of oil and gas pipelines, and as corrosion inhibitors in food industry retort cookers. 

Specify suitable control systems for the maintenance of constant conditions in the reactor against a 15 per cent change in input rate of ammonia or carbon dioxide, and examine the effect of such a change, if uncorrected, on the steam generation capability of the high-pressure condenser. 

Flow instabilities are undesirable in boiling, condensing, and other two-phase flow processes for several reasons. Sustained flow oscillations may cause forced mechanical vibration of components or system control problems. Flow oscillations affect the local heat transfer characteristics and may induce boiling crisis (see Sec. 5.4.8). Flow stability becomes of particular importance in water-cooled and watermoderated nuclear reactors and steam generators. It can disturb control systems, or cause mechanical damage. Thus, the designer of such equipment must be able to predict the threshold of flow instability in order to design around it or compensate for it. 

Condensate drainage devices, 70 148 Condensate polishing ion exchange in, 74 417 in steam-generating systems, 23 227 water softening method for, 26 122-123 Condensate return, in heat pipes, 73 226 Condensate return systems, 70 147-148 Condensate systems, in industrial water treatment, 26 136-137 Condensation, 9 281-282. See also Polycondensation control of VOCs by, 26 679-680 ketone, 74 570... 

Condensate/main header differential pressure control system. 

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