Flared casing

Na sulfate Na sulfide (Ref 3). It is used extensively in Dynamite cartridges (Ref 2) and in pyrotechnic flare and signal cases (Ref 1) Refs 1) S.M. Kaye et al, New Flare Case Materials , PATR 3215 (1965) 2) Blasters ... 

Q- FLARE CASE R- CLOSING COVER (TOP) S- SEALING STRIP... 

Straitz, J. K. "Flare Case Histories Demonstrating Problems and Solutions." Process Safety Progress 25, no. 4 (2006) 311-16. 

Skin - psoriasis in rheumatoid arthritis patients Psoriasis has been reported with rituximab therapy. A nationwide registry set up by the French Society of Rheumatology to collect data on patients was examined to assess the rates of new-onset and flare of pre-existing psoriasis in patients taking rituximab for rheumatoid arthritis. Incidence rates were 1.04/1000 person-years for new-onset psoriasis and 2.6/1000 person-years for flare. Rechallenges of two new-onset and two flare cases were not followed by recurrence or exacerbation of psoriasis. Although the number of cases observed were fairly small (1927), the findings do not support a causative role for rituximab in the promotion of psoriasis in rheumatoid arthritis patients [194 ]. 

To prepare gas for evacuation it is necessary to separate the gas and liquid phases and extract or inhibit any components in the gas which are likely to cause pipeline corrosion or blockage. Components which can cause difficulties are water vapour (corrosion, hydrates), heavy hydrocarbons (2-phase flow or wax deposition in pipelines), and contaminants such as carbon dioxide (corrosion) and hydrogen sulphide (corrosion, toxicity). In the case of associated gas, if there is no gas market, gas may have to be flared or re-injected. If significant volumes of associated gas are available it may be worthwhile to extract natural gas liquids (NGLs) before flaring or reinjection. Gas may also have to be treated for gas lifting or for use as a fuel. 

At some landfills, operators have installed flares to combust the gas without recovering any energy. Typically, these cases arise because electricity seU-back rates are too low to justify generation equipment, and laws require a reduction in methane emissions. 

Compounds considered carcinogenic that may be present in air emissions include benzene, butadiene, 1,2-dichloroethane, and vinyl chloride. A typical naphtha cracker at a petrochemical complex may release annually about 2,500 metric tons of alkenes, such as propylenes and ethylene, in producing 500,000 metric tons of ethylene. Boilers, process heaters, flares, and other process equipment (which in some cases may include catalyst regenerators) are responsible for the emission of PM (particulate matter), carbon monoxide, nitrogen oxides (200 tpy), based on 500,000 tpy of ethylene capacity, and sulfur oxides (600 tpy). 

The gaseous component typically contains hydrocarbons, hydrogen sulfide, ammonia, mercaptans, solvents, and other constituents, and is either discharged directly to the atmosphere or is combusted in a flare. The major air emissions from blowdown systems are hydrocarbons in the case of direct discharge to the atmosphere and sulfur oxides when flared. 

Restriction Orifice - In general a restriction orifice should not be used as a means of limiting the capacity of a pressurization path. In special cases, where large incentives apply (such as reducing die size of a flare system), a restriction orifice may be used, provided that all the following conditions are satisfied ... 

The drum design pressure should be 345 kPa gage, unless the drum is connected directly to the flare (without a seal drum), in which case the design pressure of the blowdown drum should be 1030 kPa gage. 

Other designs of ground flares suitable for refinery application are available. In some of these cases, noise is appreciable, in comparison with the multijet type, but their compact size, low space requirement, simplicity, and hence low cost, may give an overall advantage. 

Figure 1. Available pressure drop may in some cases dictate acceptance of a lower maximum velocity, but at least 75 m/s is recommended to insure good dispersion. Flare tips consisting of a simple open-ended pipe with a single pilot are subject to flame lift-off and noise problems at lower velocities, and should therefore be designed for a maximum velocity of 50 m/s.

Flares should be at least as high as any platform within 150 m horizontally, and in no case less than 15 m high. 

Flare elevation and spacing must be such that permissible radiant heat densities for persoimel at grade are not exceeded under conditions of maximum heat release. The appropriate calculation procedures and personnel exposure criteria are described later. In some special cases, flare elevation and spacing may be governed by radiant heat exposure of certain vulnerable items of equipment, rather than personnel. 

For services where ambient or inlet temperamres may fall below 0°C, flashback protection is provided by a special seal drum or loop seal in the inlet line. This equipment is designed specifically for the particular liquid and vapor materials being flared. In these cases a 150 mm minimum water layer is included in the bottom of the pit to prevent oil seepage into the ground, and the hydrocarbon inlet distributor is mounted 150 mm above the water surface. Details of the inlet distributor are shown in Figure 5. 

For cases (2) and (3), credit may be taken for heat transfer to the atmosphere from the flare header upstream of the seal drum. 

A flare seal drum may also be used as a sour water disengaging drum, if economically advantageous. In such cases, special care should be given to ensure that the drum is adequately sized to simultaneously meet all design features required for both functions. Also a separate source of makeup water must still be provided to ensure continuity of the seal. 

In the case of heavier-than-air purge gas, there is no buoyancy mechanism causing air entry into the stack, and there is thus no incentive to include a dry seal. Unlike a water seal, a dry seal cannot prevent a flashback from traveling upstream if a combustible mixture has been formed by the entry of air into the safety valve or flare headers. It only protects against internal burning flashback... 

Preferably, the HjS flare system should consist of a segregated header and separate line routed up the side of a conventional elevated flare stack, sharing the same structure, pilots and igniters. However, the HjS header may be tied into the regular flare seal drum if there are special mechanical design problems associated with the separate stack e.g., in the case of a flare which is to be dismantled for overhaul. Flare elevation must be sufficient to meet atmospheric pollution and ground level concentration requirements for the sulfur dioxide produced. 

Flashback protection is required for H2S flaring systems, either by water seal or continuous gas purge. If a water seal is used, special requirements apply to the disposal of the effluent seal water. In the case of an HjS flaring system handling a flow of HjS which in uninterrupted throughout the period that a plant is in operation, and which stops only when the producing plant is shutdown, then flashback protection is not required. However, steam or inert gas connections are required to permit purging the flare line startup and shutdown. 

When winterizing is required, the steam tracing and insulation should include the first 7.5 m of the flare stack above the vapor inlet and also in the case of a drum seal, the vapor line from the seal drum to the flare. Where steam injection to one of the smokeless tips, as shown in Figures 11 B and C is used, then the steam ring should remain outside the top of the flare tip (i.e., not internal). Where severe ambient conditions are encountered then it is recommended that the entire seal drum and flare be insulated in addition to steam tracing and open steam injection at base of flare. 

Flare radiation level calculations are to be based on the worst case wind velocity, a design wind velocity of 40 Kph and a maximum of 100 Kph. Vendor shall provide radiation plots for each case. 

A trial and error estimate is made for determining the diameter of the flare header based upon the maximum relieving flare load and considering the back pressure limitation of 10 percent for conventional valves and 40 percent for balanced type valves. Note, however, a single main header in most cases turns out to be too large to be economically feasible. Line sizing procedures are discussed in detail in the next subsection. 

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