Condensers fouling

Convective boiling-heat transfer coefficient Local effective cooling-condensing heat transfer coefficient, partial condenser Fouling coefficient based on fin area Heat transfer coefficient based on fin area Film boiling heat transfer coefficient Forced-convection coefficient in equation 12.67 Local sensible-heat transfer coefficient, partial condenser... 

Inerts accumulation, condensate removal, and condenser fouling are by far the most common problems that adversely affect condenser operation (381). One author (28) states that "more than half of all condenser problems are due to poor venting. Fouling in condenser- usually occurs on the coolant side and will not be dealt with here. Other problems occasionally also affect condenser performance. 

Condensation fouling] wall temperature too cold/contamination in the vapor. [Degradation] chemical reaction for amine reacts with COj and O2 forms stable salts for glycol reacts with 02/thermal decomposition for amine surface temperatures > 175 °C for glycol surface temperatures > 205 °C. 

Coke deposits in vapor line Quenching vapor line Plugged trays Condensers fouled Low pumparound duty... 

Condenser fouling. Rich amine regenerator feed splashes overhead. Particulates accumulate in the regenerator condensers, heat transfer is impaired to a certain extent, and the reflux temperature rises. 

Moving to the next subcategory of schemes, another approach is to manipulate coolant temperature. While not applicable to air-hns it does offer some advantage if condenser fouling is an issue, since it permits a high coolant flow to be maintained - no matter what condenser duty is required. As can be seen in Figure 12.37, it does require additional pumping and so is more costly to implement. 

For moderate-temperature and low-pressure condensers, such as vacuum surface condensers (see Chap. 25), a single pass on the tube side is not uncommon. These exchangers are typically fixed-tubesheet designs. Such exchangers are fine from a purely process point of view. However, there is no practical way to disassemble the exchanger to clean the outside (i.e., the shell side) of the tubes. This inability to clean the shell side frequently leads to tremendous loss of efficiency after the condensers foul. 

These various reactions should be minimized to avoid plugging the catalyst and to prevent fouling of the downstream air preheaters, when these components condense from the gas at the lower temperatures. 

Vapor-Liquid Separation This design problem may be important for a number of reasons. The most important is usually prevention of entrainment because of value or product lost, pollution, contamination of the condensed vapor, or fouling or corrosion of the surfaces on which the vapor is condensed. Vapor-liquid separation in the vapor head may also oe important when spray forms deposits on the w ls, when vortices increase head requirements of circulating pumps, and when shoiT circuiting allows vapor or unflashed liquid to be carried back to the circulating pump ana heating element. 

Fouling Industrial streams may contain condensable or reactive components which may coat, solvate, fill the free volume, or react with the membrane. Gases compressed by an oil-lubricated compressor may contain oil, or may be at the water dew point. Materials that will coat or harm the membrane must be removed before the gas is treated. Most membranes require removal of compressor oil. The extremely permeable poly(trimethylsilylpropyne) may not become a practical membrane because it loses its permeability rapidly. Part of the problem is pore collapse, but it seems extremely sensitive to contamination even by diffusion pump oil and gaskets [Robeson, op. cit., (1994)]. 

Donavan, E. J. Jr., Evaluation of Three Anaerobic Biological Systems Using Paper Mill Foul Condensate, HydroQual, Inc., EPA, lERL contract 68-03-3074. 

PMFC = paper mill foul condensate (5,6) NOTE MG =3785 m. ... 

Also, pilot plant and laboratory scale anaerobic studies have demonstrated successful treatment of wastewaters of 5,000 to 50,000 mg/L GOD from corn chips containing soluble and colloidal corn starch and protein, cheese whey, organic chemicals, food, bakeiy, breweiy, paper mill foul condensate, paint, and numerous other hazardous anci non-hazardous materials. 

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