Atmospheric vent stack

Atmospheric corrosion. Air-cooled heat exchangers should not be located where corrosive vapors and fumes from vent stacks will pass through them. 

To prevent leaks of carbon monoxide and hydrogen from the glands of a number of compressors getting into the atmosphere of the compressor house, they were sucked away by a fan and discharged through a small vent stack. Air leaked into the duct because there was a poor seal between the duct and the compressor. The mixture of air and gas was ignited by lightning. 

This particular design is most effective in reducing SRV discharge noise to safe levels and equally effective in reducing noise from superheater vent stacks, process waste gas stacks and other sources discharging steam, air or gases into the atmosphere (Figure 8.3). 

Closed system (to vent stack, burning stack or scrubber) Open system (to atmosphere)... 

Liquid drains, manifolded and taken to a heater for vaporizing, process safety valves, vents and thaw lines, together with the major casing vents, all culminate in a vent stack to the atmosphere. This stack should have its exit point well above surrounding equipment to prevent it from being a hazard to personnel in the event of a fire. A continuous flow of nitrogen at a velocity of 1 ft/sec can be supplied at the bottom of the vent stack to blanket all process and casing equipment from air. A check valve placed in this line provides added protection. 

When the plant is to be shut down and equipment warmed to ambient temperature, the hydrogen gas is dissipated to the atmosphere in an open area by use of a vent stack. 

Pressure relief equipment includes relief valves, safety valves, rupture discs, piping, drums, vent stacks, pressure indicators, pressure alarms, pressure control loops, and flare systems. Pressure relief devices can be placed on pumps, compressors, tanks, piping, reactors, distillation columns, refrigeration systems, and many other kinds of equipment. Materials that cannot be released to the atmosphere are recycled back to the system, or sent to a scrubber or flare system. The discharge from pressure relief equipment is collected in a closed piping system and sent to a flare stack. Harmless gases are discharged at a safe distance from plant operations areas. 

Sponge coke, 46—48, 70 Stack damper, 317-318, 320 process heaters, 317 Stacked paper plates, 94 Stainless steel, 416-418, 424-425 field identification of pipe, 417-418 cracking, 424-425 Start-up stack, 123 Start-up tips (sulfur plant), 134 Start-up (pump cavitation), 246-247 Start-up (sulfur recovery), 122-124 oxygen supply, 123 atmospheric vent, 123-124... 

The most common method of disposing of hydrogen is by venting to the atmosphere. Venting should be done through a vent stack that discharges at an elevated point. It should be done at a controlled rate in an isolated area remote from sources of ignition and away from air intakes. 

Each main steam line goes from its steam generator and passes through the containment boundary. The first valve encountered in each line is the main steam isolation valve, which is outside the containment boundary each isolation valve has a bypass valve in parallel with it. Beyond the main steam isolation valve in each of the two steam lines are the six steam safety valves every one of these safety valves vents to atmosphere through a discharge pipe and vent stack. Downstream of the safety valves is the power-operated atmospheric relief valve, which vents to atmosphere through a vent pipe and silencer. The operation of the power-operated relief valves is automatically controlled by steam line pressure during plant operations the power-operated relief... 

Once testing was completed, the RD was drained to atmosphere through the Cell 7 heat exchanger (HEX) and vent stack. Residual vapors in the flow system were purged using dry GHe. Then both the ST and RD were brought back to ambient pressure. Videos of the LAD screen were transferred to an external hard drive to be analyzed post-test. 

Once testing was complete, any residual vapor was directly vented through a vent stack to atmosphere. The tank and flow lines were purged with GHe. The pressure in the RD was brought back to ambient conditions. Videos of the LAD screen were then transferred to an external hard drive. 

Figure 6.30 shows the grand composite curve plotted from the problem table cascade in Fig. 6.186. The starting point for the flue gas is an actual temperature of 1800 C, which corresponds to a shifl ed temperature of (1800 — 25) = mS C on the grand composite curve. The flue gas profile is not restricted above the pinch and can be cooled to pinch temperature corresponding to a shifted temperature of 145 C before venting to the atmosphere. The actual stack temperature is thus 145 + 25= 170°C. This is just above the acid dew point of 160 C. Now calculate the fuel consumption ...

Atmospheric Distillation and Vacuum Distillation Heater stack gas (CO, SO, NO, hydrocarbons and PM), vents and fugitive emissions (hydrocarbons) Steam ejector emissions (hydrocarbons), heater stack gas (CO, SO, NO, hydrocarbons and PM), vents and fugitive emissions (hydrocarbons). 

Because of extreme venting conditions assumed, effective stack heights and resultant plumes from both 3- and 5-minute discharge conditions attain heights beyond the micro-meteorological conditions assumed in accepted computation models. It is therefore highly probable there will be considerably further atmospheric dispersion and diffusion of the VCM than predicted in the results shown. That is, the ground level concentration can be expected to be considerably lower than the values shown in Table 6. 

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