Equipment purging

Increased maintenance cost for process equipment due to safety requirements (for example, safety permits, cleaning and purging equipment, personal protective equipment, training, and restricted access to process areas). 

Production records Processing records and production logs Product specification sheets for existing and new products Bleed runs used to purge equipment which cannot be cleaned before use Best-before dates or batch numbering systems... 

Various protection techniques can be used to prevent electrical equipment from becoming an ignition source. Explosion-proof enclosures, pressurized and purged equipment, and intrinsically safe circuits can be used in Division 1 and Division 2 locations. Nonsparking equipment can be used in Division 2 locations. Details of the types of equipment permitted in each classified location are given in NFPA 70. 

In most practical combustion installations there are two separate parts of the equipment system (1) the burner itself and (2) all of the peripheral equipment necessary to control the burner operation efficiently and safely. The control equipment includes fuel and oxidant pressure and flow controls automatic shutoff controls flame supervision equipment furnace purge equipment and other related devices. The safety issues of the burner are significantly different in character as compared with the safety issues of the control equipment. In many ways, these two safety issues are diametrically opposed. Within the burner, fire is a desired condition, whereas within the control system and surrounding environment, fire is to be avoided entirely. 

FIGURE 10.7 Typical forced-air purge equipment for use in an oxygen/fuel combustion system. 

In order to maintain a certain atmosphere in the electrolytic cell, a gas purge equipment should be provided. For example, inert gas such as nitrogen or argon gas can be bubbled in the... 

One of the most common, and successful, subtractions is the removal of water vapour. The physical removal of this from the spectrometer takes time and expensive purging equipment. However, equally good results can sometimes be achieved by keeping on disc an absorbance spectrum of water vapour and subtracting it whenever necessary. Bands between 1800 and 1450 cm are particularly vulnerable to water vapour. Figure 10.8 shows the results of a subtraction on the amide I band of haemoglobin. 

N2 production catalysts. During the chemical processes, N2-rich gas or pure N2 as inert carrier gas is frequently used for replacement or purging equipments and piping and protecting the catalyst. 

Constant-temperature decomposition or combustion, followed by trapping and weighing the volatilized gases, requires more specialized equipment. Decomposition of the sample is conducted in a closed container, and the volatilized gases are carried by a purge-gas stream through one or more selective absorbent traps. 

Fig. 4. Equipment flow sheet of elemental fluorine production and liquefaction plant, 9 t/d capacity. Step 1 purging residual F2 at rates indicated all but a trace of residual F2 is removed in 15min N2 purge is maintained for 1 h to remove last traces. Step 2 HF removal at rates indicated all but a trace of HF is...

Inasmuch as the gas hydroly2es readily, all equipment should be purged repeatedly using inert dry gas before admitting boron trifluoride. Under anhydrous conditions, carbon steel equipment is satisfactory. Stainless steel and aluminum siUcon bron2e may also be used. Stainless steel tubing is recommended for both temporary and permanent connections. 

Electrical Hazards. Because carbon fibers are conductive, the airborne filaments can create serious problems shorting out electrical equipment. The best option is to locate sensitive equipment in clean rooms outside of areas where carbon fiber is being processed. If this is not possible, electrical cabinets must be effectively sealed to prevent contact with carbon fibers. A filtered air-positive purge provides additional protection for sensitive equipment. 

In addition to chemical synthesis and enhanced oil recovery, gaseous carbon dioxide is used in the carbonated beverage industry. Carbon dioxide gas under pressure is introduced into mbber and plastic mixes, and on pressure release a foamed product is produced. Carbon dioxide and inert gas mixtures rich in carbon dioxide are used to purge and fiH industrial equipment to prevent the formation of explosive gas mixtures. 

---