Towers maintenance

This secondary reaction starts at about 180°C, but the mass must be heated to 350—400°C to bring the reaction to completion and produce a nitrate-free product. The off-gases are extremely corrosive and poisonous, and considerable attention and expense is required for equipment maintenance and caustic-wash absorption towers. Treatment of the alkaline wash Hquor for removal of mercury is required both for economic reasons and to comply with governmental regulations pertaining to mercury ia plant effluents. 

Maintenance cost. Maintenance for air-cooled equipment as compared with sheU-and-tube coolers (complete with coohng-tower costs) indicates that air-cooling maintenance costs are approximately 0.3 to 0.5 those for water-cooled equipment. 

Two types of mechanical-draft towers are in use today the forced-draft and the induced-draft. In the forced-draft tower the fan is mounted at the base, and air is forced in at the bottom and discharged at low velocity through the top. This arrangement has the advantage of locating the ran and drive outside the tower, where it is convenient for inspection, maintenance, and repairs. Since the equipment is out of the hot, humid top area of the tower, the fan is not subjected to corrosive conditions. However, because of the low exit-air velocity, the forced-draft tower is subjected to excessive recirculation of the humid... 

Rendering plants Feedstock storage and housekeeping Cookers and percolators Grinding Odors SO2, mercaptans, ammonia, odors Particulates (dust) Quick processing, washdown of all concrete surfaces, paving of dirt roads, proper sewer maintenance, enclosure, packed towers Exhaust system, condenser, scrubber, or incinerator Exhaust system and scrubber... 

Horizontal natl. circ. Ease of maintenance Lower skirt height than vertical Less pressure drop than vertical Longer tubes possible Less cost than kettle No theoretical tray Extra space and piping as compared to vertical Fouls easier as compared to vertical Accumulation of higher boiling point components in feed line, i.e., temperature may be slightly higher than tower bottom... 

Maintenance and production records, along with the used lean and rich glycol analyses, can be very helpful to the troubleshooter. A history of filter element, carbon, tower packing, and firetube changeouts can sometimes be very revealing. The frequency of pump repairs and chemical cleaning jobs is also beneficial. With this type of knowledge, the troubleshooter can quickly eliminate and prevent costly problems. 

Large towers often have the motor mounted horizontally connected to a right angle gear drive. The motor can be closely coupled- in the air stream- or connected with a drive shaft with the motor outside the air stream. Maintenance personnel typically prefer the external TEFC motor- when available- for its easier access. Cooling tower fans- like all fans- operate in accordance with the fan laws one of which states that the horsepower required to drive a fan increases to the cube of fan speed. 

The last batch of MIC, before the accident, was produced in the interval October 7-22, 1984. At the end of the campaign the E610 storage tank contained about 42 tons of MIC, and the E61 i storage tank contained about 20 tons. After which, MIC production was shut down, and parts of the plant were dismantled for maintenance. The flare tower was shut down to replace a piece of corroded pipe. 

Inspections showed that two cooling towers contained asbestos. Sticky warning labels were fixed to them. No maintenance work was carried out... 

A 2-ft tower would be expected to perform satisfactorily with properly designed trays. However, a 2.5-ft tower is the minimum diameter suitable for internal inspection and maintenance. The cost of a tray tower of 2.5-ft has been found to be no more, and from some bids 5 percent less, than the smaller 2-ft. tower. A 2-ft. tower would either be used with packing or with trays inserted from the top on rods with spacers. This would allow removal of the trays for inspection and maintenance. 

Additional detailed information is available from the Cooling Tower Institute, including ATF-105 Acceptance Test Procedure for Water-Cooling Towers, STD-101 CTI Grades of Redwood Lumber [31], STD-102 Structural Design Data [70], and TSC-302 Cooling Tower Wood Maintenance [16],... 

Cooling Towner Wood Maintenance, TSC-302, Cooling Tower Institute, Palo Alto, Cahf. 

Having selected and purchased a cooling tower, it needs regular maintenance, as does any other part of the plant. This is true of every cooling tower, from the largest natural-draft tower to the smallest packaged unit. 

While the majority of cooling tower installations work efficiently, the normal requirements of maintenance and good efficiency practice have still to be applied. This may not always be the case. Time for maintenance is limited, and plant engineers have other pressing problems or, as is well known, forget about the towers With the increasing economic and environmental pressures on the use of water, this situation must change. 

In most climates the wet bulb temperature is well below the dry bulb temperature and there is an advantage in using water or evaporative cooling for larger plant. These options need to be investigated and compared. The present concern over spray-borne diseases may indicate a preference for air cooling in the vicinity of institutions but correct maintenance of water cooling towers and evaporative condensers will permit their use elsewhere. Table 10.2, based on the tentative temperature differences of 15 K and 12 K... 

INDUSTRIAL Water Society Guide to Mechanical Draught Evaporative Cooling Towers Selection. Operation and Maintenance (London, 1987). 

Different snow and ice making systems have been tested. The first years both fan type snow guns and one LowEnergyTower were used. The fan-type machines required a lot of maintenance and surveillance the first years and a lot of the snow from the LowEnergyTower landed outside the storage. The last year s two fan type snow guns have been used, mounted on 5 m high towers and now only operated in the wind direction. This worked well. 

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