Seal systems

This method is slow because of the multiple operations on a shuttle machine. The heat of extmsion sterilizes the bottle, which is not readily achieved after molding. Blow-mold/fill/seal systems are used commercially for beverages and for pharmaceutical packaging. 

At the top of the furnace, the raw materials are charged into the furnace through a pressurized gas seal system, typically a double beU (see Fig. 6a). For very high pressure furnaces, three bells may be used. More recently, the Paul Wurth beU-less top has become popular, as its rotating chute design permits greater control over distribution of the burden (Fig. 6b). 

Fig. 6. Pressurized gas seal system at top of blast furnace (a) two-beU top and (b) beU-less top.

Space needs to be provided for the auxiliaries, including the lube oil and seal systems, lube oil cooler, intercoolers, and pulsation dampeners. A control panel or console is usually provided as part of the local console. This panel contains instmments that provide the necessary information for start-up and shutdown, and should also include warning and trouble lights. Access must be provided for motor repair and ultimate replacement needs to be considered. If a steam turbine is used, a surface condenser is probably required with a vacuum system to increase the efficiency. AH these additional systems need to be considered in the layout and spacing. In addition, room for pulsation dampeners required between stages has to be included. Aftercoolers may also be required with knockout dmms. Reference 8 describes the requirements of compressor layouts and provides many useful piping hints. 

However, when the temperature is increased to 120°C, the principal reaction is the elimination to olefin. The thermal decomposition of dimethyl dodecyl amine oxide at 125°C in a sealed system, as opposed to a vacuum used by Cope and others, produces 2-methyl-5-decyhsoxa2ohdine, dimethyl dodecyl amine, and olefin (23). The amine oxide oxidi2es XW-diaLkylhydroxylainine to the nitrone during the pyrolysis and is reduced to a tertiary amine in the process. 

Dust entrained in the exit-gas stream is customarily removed in cyclone cohectors. This dust may be discharged back into the process or separately cohected. For expensive materials or extremely fine particles, bag collectors may follow a cyclone collector, provided fabric temperature stability is not hmiting. When toxic gases or solids are present, the exit gas is at a high temperature, the gas is close to saturation as from a steam-tube diyer, or gas recirculation in a sealed system is involved, wet scrubbers may be used independently or following a cyclone. Cyclones and bag collec tors in diying applications frequently require insulation and steam tracing. The exhaust fan should be located downstream from the cohection system. 

Vapors (from drying) are removed at the feed end of the dtyer to the atmosphere through a natural-draft stack and settling chamber or wet scrubber. When employed in simple drying operations with 3.5 X 10 to 10 X 10 Pa steam, draft is controlled by a damper to admit only sufficient outside air to sweep moisture from the cylinder, discharging the air at 340 to 365 K and 80 to 90 percent saturation. In this way, shell gas velocities and dusting are minimized. When used for solvent recovery or other processes requiring a sealed system, sweep gas is recirculated throu a scrubber-gas cooler and blower. 

Arkel refining a sample of tire impure metal, for example zirconium, is heated to a temperature around 550 K in contact with low pressure iodine gas in a sealed system which has a heated mngsten filament in the centre. The filament temperature is normally about 1700K. At the source the iodides of zirconium and some of the impurities are formed and drese diffuse across the intervening space, where tire total pressure is maintained at 10 auiios, and are decomposed on the filament. The iodine then remrns to form fresh iodide at the source, and the transport continues. 

The Cartridge Concept - has every component part of the sealing system in one unit. They re easier and faster to install and don t require total pump teardown. Most come with additional control ports and rebuild kits. 

Dry gas seals, when eeonomie eonsiderations allow, are another alternative for redueing gas leakage. Dry faee-seal systems have been used sueeessfully and field experienee has proven their effeetiveness. 

This API Standard 614 standard eovers the minimum requirements for lubrieation systems, oil shaft sealing systems, and related eontrol systems for speeial purpose applieations. The terms are fully defined, referenees are well doeumented and basie design is deseribed. Details of the lubrieation system are presented in Chapter 15. 

Seals are very important and often critical components in turbomachinery, especially on high-pressure and high-speed equipment. This chapter covers the principal sealing systems used between the rotor and stator elements of turbomachinery. They fall into two main categories (1) noncontacting seals, and (2) face seals. 

The following is a list of faetors that have proven to be helpful in seal system design and seleetion ... 

Figure 13-31. Restrictive ring seal system with both buffer and eduction cavities.

Contamination from Seai Gas Suppiy. Contamination from the seal gas supply oeeurs when the sealing gas is not properly treated upstream of the dry gas seal. Gas seal manufaeturers have stringent requirements for seal gas quality. Typieally, the sealing gas must be dry and filtered of partieles 3 mieron and larger. Filters are normally provided in the gas seal system to meet this requirement. 

Dry gas seals operate under extremely tight toleranees, whieh demand that speeial eare be taken in the design of the gas seal environment, and in the operation of the eompressor and gas seal system. While the threat of seal degradation and redueed seal life due to outside influenees is real, the detrimental effeets of these faetors ean be minimized. 

Lubricating-oil governor and seal system cleaned Instrumentation and speed control checked Auxiliary heat recovery system Centrifugal Compressors... 

The contact seal can be used under 1,000 psig. It is more complex, but has the advantage of not leaking while shut down. The contact seal is used extensively in refrigeration service where the compressor is part of a closed loop, and the shutdown feature is desirable. As mentioned, the seals must have a source of cooling and buffer fluid. In many cases, this fluid is lubricating oil. If contamination is not a problem, a combined lube and seal system can be used. 

Probably the biggest single advantage of dry gas seals is getting rid of the seat oil. The seal oil system, even when part of a combined lube and seal system, is a complex assembly. With the dry gas seal, the lubrication oil system is all that is needed to service the compressor train bearings and, on turbine driven units, to also supply turbine control oil. As. ui aside, it makes feasible the dream long held by the compressor vendor of having a standardized lube system line. 

Figure 8-15. Typical dry gas seal system schematic for a tandem arrangement dry...

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