Document e7pExvyrDnwoxQa0JKvX3LK3q

(he weak pump becomes hard to start, unreliable in operation. All burners and fuel-oil pumping equipment require strainers in the suction line to protect them from foreign matter. Perforated-metel or wire-mesh strainer baskets serve for residuol oils. It is also customary to install a discharge strainer ofter the oil has passed through preheating equipment, especially for mechanical* atomising burners. Beturn Linos. Fuel-oil pumps ore usually rated to deliver ot least up to 1.5 times the burning rate. On socalled one-pipe installations where there's only a suction line, excess oil is diverted from the discharge line bock to the suction side of the pump. The customary and preferred procedure is to run a return line baek to the storage tank so all excess flows baek to tank. For residual oil this return circula tion Is highly important. This excess oil already has been preheated and its return to storage raises the over-all temperature at the storage tank, mak ing pumping easier. The return line provides the further advantage of venting the piping system without the aid of special venting valves required with one-pipe designs. Return-line pipe sixes are usually made the tame as for the suction line. When return line rises above the burner on its way to the storage tank a check valve goes In near the burner hinge but there should be no other valves, shut-offs or obstructions. Where there's more than one tank, and you need to install valves in the return line to di vert oil to either tank, insert, a relief valve in the bypass line. Valves.'OU supply lines from stor age to burner must carry readily acces sible shutoff valves of approved type near each burner and close to gravity and pressure supply tanks. Usually they go in on each side of the oil strain ers and on the discharge end auction side of oil pumps. If there is one on the discharge side of an oil pump an opproved pressure-relief volve should go in to return surplus oil to the tank or bypass it around the pump. Further, approved automatically operated valves designed' to shut off oil in case of breakage of the oil supply line are smart where burners ore not equipped to prevent abnormal dis charge of oil at the burner. Anti-siphon valve* once required by NBFU for this kind of service are no longer a necessity and should not be put in unless local regulations demand it. A good tight suction line with a check valve near the burner gives a very good guarantee that the suction line will stay Ailed and the pump will not lone its prime. 96 Preheating OH. AU No.. 6 fuel oils and most No. 5's have to be preheated for efficient handling and combustion. How dosely oil temperature, and hence viscosity at the burner, must be con trolled depends on stomlsing method. For fliechonicat-otomixing burners, recommended viscosity is ISO ssu at 100 F. Temperature to produce this viscosity depends on the fuel oil used. The Navy rule puts temperature at 135 F plus the saybolt furol viscosity at 123 F. Rotary cup burners handle oils of viscosities up to 300 ssu, while steam- or air-atomising burners per mit an even wider range. There is a danger of vapor locking in the suction side of an oil pump if all preheating Is done before the pump. Top temperature in the suction line should be of the order of 80 to 110 F and no more. For simplicity's sake, many installations hove all their pre heating on the discharge side of the pump. But often, especially In cold climates, some preliminary preheating has to be done at the storage-tank stage. Preheaters, or fuel-oil heaters as they are often called, may use steam, hot water or electricity as a heating medium. Electricity serves best for starting up a cold plant. Preheaters using steam or hot water are of shell-and-tube arrangement with the oil passing through the tubes and the heating medium passing through the shell over the tubes, or vice versa. High-pressure steam plants use steam almost entirely. FUCl HANDLING AND STORAGE But because this steam t. temperature and n c.Ute *'; to handle gas economically and safely the oil and rapid fouling 0f thermostatic regulator, ,h ' the team line supplying difference between gas and with the thermoitatic oil dlacharge line. A. . tunL. ^^lid liquid fuels is that gas * % la lmMt Invariably the re- guard, a magnetic eteam valv, team line before the regular. * '^Sbllity Ihe supplier and storage 'i consumer's premises is rare. when the hurner itart, SS/rueh large-seale storage of the bea)' .^tf.tnd-awoy most important gate- hydrogen sulAde shows up in a gas It may be from a trace to 10 or 15% by volume. For each 1% HjS by volume you can figure about 0.1 lb of sulfur per 100 cu ft Usually,-gas when produced Is saturated with water va por at prevailing pressure, temperature. matter. An odorant is added for safety. The gas reaching the customer is thus nearly all pure fuel and his problem is reduced to delivering this fuel safety to firing units. An example from the setup of a large user (Powbs, Nov 1951, pp 90-94) gives on kleo of what steam within the preheater &rfffcuell, nnaatt"urall I ** 'datively new. attendant extreme temperature ri.. U * the atandlng oil within the healTM Ij' rvjgfljndous expansion of natural'Ajg |nto Aelds like house heating, to. a demand that, varies obove'sO ZhlJS'1" W'"" "-- hLo-u,r- !*"* I'0U-'- The gas-trantmlsiion company con ditions the product by (I) removing water and liquid hydrocarbons (2) taking out hydrogen sulfide and inert gases (5) removing dirt and foreign is involved. Typical Largo Systam. A typical large-scale user of natural gas gets supply from a pipeline at 100 pti, through a 22-in. line connecting to a lt P*1 lood operate- practice. The heater installation njS'V' * mbW* ** operated economically at larger and. hence costs more but h'* returns solid advantages in the way of ^ Wfr rates. As a result, gas 'y^dc available at the source ot rea- reduced operating costs, less coking ^n' y content rates, as close as pos- oil, better regulation of oil dlsehsrtfr temperature, greater service and long.>* 'aij.'to capacity ratings of the lines. 1 (jadergroumf Storage. With vlrtu- er life of the fuel-oil heater. .Mi' dhW gas-storage facilities in con- Insulation. Since temperature playr'V ffijfr plants, the problem of maintain. so important o part in the bsndUngSri kgiUgb economical transmission and combustion of fuel oil, thorougljl/ij flirt in spite of widely varying and efficient insulation of ail piping,'-'.-,' iMomer demand has been solved heaters, etc., is a sensible move. Via increasing extent by underground Materials like 85% magnesia, 0Ttf* in 1952, close to 150 large stor- eral wool, or asbestos slr-ceU do Iqtlprojects. with total capacity of good job on in-plant piping, with pin. $] toot 1,000,000 MMcf were in opera- tic cement taking care of the various^' ,5m,1 from New York to California, pipe Attlngs. Hoirfeit and tar paper^t1 iifieblgsn to Texes. In the Appalachian are often used for underground piping.1*/ 'qioo alone there are more than 100, 3Frequently the fuel-oil suction line, rfei combined capacity exceeding 600, return line and steam or hot water., WOiMMef. More are planned. supply and return lines to the storage-tar !~Such underground storages have tank heating coil are wrapped together;-.^ Wn developed from depleted or part- aa one bundle. ^depleted gas fields, oil fields, aban- '$xmJ noncommercial gas Aelds and bmerly untested water sands. Some ' extremely large -- the Oakford faraie field of New York State Notu- ita^Qts Corp (near Jeannette, Pa.) tab 1,000,000 Mcf. t^Osi Proporiles. The notural-gas pipeline company customarily condi- ,`tjeni the gas to give it qualities and Pppertles that make it more tram- ;$(aible and more desirable to the cut- Methane and ethane constitute ;"f'bulk of the combustibles, raeth- varying in volume from 60 to Ethane, propane, butane, hexane, follow in decreasing percentages. vCaibon dioxide and nitrogen form ,4s bulk of the Inert portion. Carbon ^Mde ranges from a trace, to 100% tV^nie Pocky Mountain area wells, .*Vi< nitrogen averages out at about by volume for the various U. S. .Sfc. Helium also occurs in natural 'If','but is. usually less than 1%. *800,e gas fields produce gas con- ,7|h| hydrogen sulAde and the van- sulfur compounds known as mer- tjjptans, A gas with hydrogen sulfide ..known as a "sour" gas. while one *jbout it is a ``sweet"' gas. When RECOMMENDED PRACTICES FOR INDUSTRIAL GAS PIPING LOCATION. Be sure piping is located with safety in mind. Avoid putting it under floors, In unventilqted crawl spaees or concealed in solid masonry. If you have to, enclose it la a larger pipe, sealed but provided with means for leak Inspec tions at the inner end of the easing. Never lay gas piping in cinder All. Protect buried steel pipe against corrosion by suitable coating, or cathodic meant. Remember that many gases, particularly manufactured, con tain moisture. Whether above or below ground, piping should not be exposed to freexing temperatures. MATERIALS. Standard-weight (ASA Schedule 40) steel pipe it acceptable and generally used since pressures are relatively low, usually below 25 psi. In smaller pipe sixes, fittings ore screwed type, mode of malleable iron, cast or forged steel. Larger sixes (4-in. and over) often use cast-iron fittings but welding fittings and - welded or gland-type joints have become quite general. Por the latter, check your local gas supplier for gland materials - resistant to the gas they furnish. SIZING. Estimate maximum rate of gas consumption (cu ft per hr) by dividing equipment input rating in Btu's per hr by the Btu per cu ft of the gss supplied. Load diversity may be figured in, but best practice usually designs pipe for maximum rating, so there is room for growth and changes in specific gravity or heating votue of the gas supplied. Allowable preasure loss from meter to point of use under maximum gas demand can be selected by allowing cither 0.5In. water, or 10% of Initial pressure, whichever Is greater. Equivalent pipe length to use In determining pressure loss is taken as actual length plus equivalent length ollowances for Attlngs shown in Table XIV, Piping Handbook, 4th ed. INSTALLATION RULES. Never weaken the building structure by such shortcuts as notching beams to install piping. Never hang, strap or otherwise support gas piping from other piping or electrical conduit Securely fasten and support gas piping with hooks, straps, bands or hangers spaced at Intervals no greater than; 8 ft for 44- and 1-in. pipe, 10 ft for 144-in, or larger pipes in horixontal runs; ot every floor level for 144-in. or larger vertical pipe*. Orade piping with a pitch of at least 1 In. In SO ft and pro vide a drip at any low point where condensate could collect Allow for expansion bends or gland-type couplings in long runs of 4-in. or lorger piping. Expansion bends should follow usual good practice for radius, uniformity of curvature, uni formity of wall thickness. Locate gland-type couplings where they can be readily inspected and maintained. (Turn page) ISCIMIH IMJ full HANOLING AND STQtAOE