Document Vj0YVLMvROG3r7Vp7jvqZR4Y4

TOWOLDMONOQ30322 'Trade name reg. U. S. Pat. Off. 1248 0J4729V TOWOLDMONOQ30323 .......................... has been used successfully since 1941 as a liquid phase heat transfer medium at atmospheric pressure and temperatures up to 600F. The compound, essentially tetrachlorobiphenyl, is a fire-resistant and non corrosive liquid, which does not crystallize at low temperatures. Handled properly, in well-designed forced circulation heat exchangers which avoid localized over heating damage, the fluid gives satisfactory continuous service for many years without replacement. Most significant, Aroclor 1248 is practically non-flammable. In one in stallation of record, a ruptured pipe spewed the hot fluid into gas flames: the fluid failed to ignite! For general heat transfer, Aroclor 1248 has several other important qualities: it is highly mobile and can be readily pumped at temperatures as low as 50F. If cooling is necessary, the heat transfer fluid can be put through a water cooler to be used as a coolant . . . using this single fluid for both heating and cooling. Aroclor 1248 transfers heat (up to 600F.) as a liquid. This liquid phase heat transfer makes it unnecessary to use the expensive pressurized equipment required by a heat transfer medium that operates as a vapor. Aroclor 1248 operates safely and efficiently with gas-fired, oil-fired, or electrical heat sources. It is used successfully in the following types of applications .... .  Chemical Processing Equipment, particularly for reacting flammable materials Cooking of Alkyd resins, varnishes, waxes Plastics molding, extruding, calendering Rubber processing Heating asphalt Food Processing, including potato chip and doughnut frying in vegetable oils Processing titanium, magnesium, other non-ferrous metals Fabrication of magnesium and aluminum honey-comb structures for aircraft Indirect heating in dyestuff manufacture Heating of corrugating rolls Indirect heating of distillation equipment Saponification of fats Calcining Ovens Impregnation and lamination of fibrous materials 0* 0347301 TOWOLDMONOQ30325 W'Nswrn TABLE I Appearance Absolute density, g./ml. Absolute viscosity, centipoises Thermal Conductivity, Btu./hr./sq. ft./F./ft. Spec. Volume, ml. g. Practically colorless mobile liquid. Temperature 'Centigrade 'Fahrenheit 1.44 30 86 1.41 60 140 1.37 100 212 1.27 200 392 1.17 300 572 112.0 30 86 17.5 60 140 4.2 100 212 0.99 200 392 0.47 300 572 0.0571 30 0.0564 60 0.0555 100 0.0534* 200 0.0512* 300 `Extrapolated Data 86 140 212 392 572 0.696 0.709 0.728 0.787 0.860 30 60 100 200 300 86 140 212 392 572 CONTINUED A7 TOWOLDMON0030326 VISCOSITY OF AROCLOR 1248 TOWOLDMONOQ30327 n -30 * 20 Figure 3 0 20 40 VISCOSITY, SAYB0LT UNIVERSAL SECONDS VISCOSITY OF AROCLOR 124$ (Saybolt Universal Seconds) 100,000 - 20,000 5.000 3.000 1,500 750 400 200 100 60 50 45 40 35 I I II! 100 120 140 160 180 TEMPERATURE, DEGREES FAHRENHEIT )| I 200 220 240 I I I! 260 280 300 320 I 33 340 350 0 3 $ 7 30 TOWOLDMONOQ30328 HEAT CAPACITY and Its Relationship to Density Systematic errors exist in the various accepted pro cedures for making specific heat determinations. Consequently values may vary depending upon the procedure used. In practical operation, it frequently appears that the values for Aroclor 1248 shown in Figure 4 are somewhat low. Consequently, although these values have been accurately determined, they may be regarded as conservative. When comparing the specific heat values of Aroclor 1248 with corresponding values for other heat transfer fluids, it is important to note that the density of Aroclor 1248 is much higher, relatively, than the density of other liquids used for heat transfer. Accord ingly. when comparison of heat capacity is made on a volume basis (which is most pertinent in equipment design and efficient operation) the heat capacity of Aroclor 1248 shows itself to better advantage than by direct comparison of specific heat values. Although specific heat values are important, they represent only one of several important constants that enter into the equations for calculating over-all heat transfer efficiency. Through the use of these conservative heat capacity values, it is possible that equipment engi neered from such data might be slightlv "over designed." This may be one of the factors that accounts for the exceptionally good operating per formance of a number of highly successful commercial applications. 0'i<,730^> TOWOLDMONOQ30329 SPECIFIC HEAT OF AROCLOR 1248 (Bhi. per lb. per decree F.) - :-7 r^pfTE^^iawiw ~T~. :;rr^RB&28S!9MMHi .^^9SB8Hmiinnni 8imiBmnHni 5?*gs*R8HmnHi M ^^^RSISlSIRSiniMj wmmmmmmmmmmmwmmwm T!Srf^PilIiiIIlIiiiiii ?^99SHS3mniPiRaniHiw '; l^SiilliPi#" JlSaiRgSKIlSSSOT - ____________ _,,a --^w^mmmmwwmMwmmmji >! rr * - ^v^mmmmMrnwmmmm^mmm '^^^^^p^p*piiRaFTTOPiiir---------------------- --.. ^pe .twt zj jg f? *4* 0.34 --.~~y 0.33 vzmmmmmxmss*-: ;:mmmmmm ,, 0.32 0.31 0.30 0.29 0.28 0.27 SPECIFIC HEAT Btu., !b./T. 03^7300 TOWOLDMON0030330 Temperature c. *F. 0 32 10 50 38 100 66 150 93 200 121 250 149 300 177 350 204 400 232 450 260 500 288 550 316 600 TABLE II HEAT CONTENT of Aroclor 1248 Specific Heat Btu./lb./F. .269 .272 .280 .288 .295 .303 .311 .319 .327 .335 .343 .351 .359 Heat Content Btu./lb. 0.0 4.85 18.65 32.85 47.43 62.38 77.58 93.48 109.66 126.21 143.17 160.52 178.27 0 03 hi 30 7 10 TOWOLDMONOQ30331 THERMAL CONDUCTIVITY and VISCOSITY The thermal conductivity values of Aroclor 1248 are shown in Figure 5. The curve shows this value over the operating temperature range, from 50"F. to 600~F., of Aroclor 1248. As freshly charged into a heat exchanger. Aroclor 1248 has an initial viscosity of 74 (S.U.S.) at 130F. which corresponds to a viscosity of approxi mately .5000 (S.U.S.) at 50"F. -- which temperature is assumed for practical purposes to be about the limit at which Aroclor 1248 can be conveniently pumped with a centrifugal pump. The following table shows a comparison of the initial viscosity and the viscosity after a year's con tinuous service at 600`F. in a LaMont forced circu lation heater: TABLE III Appearance Specific Gravity, 65 C. Viscosity, S. U. S. at 130'F. Original Colorless liquid 1.410 74.0 After one Year of service at 60Q'F. Dark Brown Liquid 1.418 83.5 Although Aroclor 1248 tends to darken in use. this darkening is not harmful and does not indicate decomposition. In actual use at Monsanto, it has not been found necessary to replace the fluid after seven years of continuous use; additional fluid is only added as necessary to make up spills or leaks. In Figure 6, the horizontal line indicating vis cosity limit of pumpabilitv at 50F. shows that the rate of viscosity increase based on a year's continuous service should permit Aroclor 1248 to serve approxi mately four years before increased viscosity may inter fere with its pumpabilitv when cold. In practice, Aroclor 1248 has given satisfactory pumpabilitv for much longer periods. A simple S.U.S. viscosity deter mination by the ASTM-D-88 method can be used for periodic checks on the fluid. 034 7306 TOWOLDMONOQ30332 j THERMAL CONDUCTIVITY OF AROCLOR 1248 | (Dotted extension indicates extrapolated data) TEMPERATURE Figure 5 $ 0.060 0.055 THERMAL CONDUCTIVITY. Btu.. (Hr.) (Sq.Ft) (''F.XFt.) 0.050 0347 304 TOWOLDMONOQ30333 1 0% Figure 6 EXPECTED MINIMUM SERVICE LIFE IN A FORCED CIRCULATION HEATER 140 130 120 no 100 90 80 70 03 13 TOWOLDMONOQ30334 VISCOSITY, SAYBOLT SECONDS, at 130F. STABILITY Aroclor 1248 is an extremely stable chemical com pound. Tests over long periods of time have shown that 600F. is a safe maximum temperature for continuous operation in heaters that are properly designed and operated to eliminate intense, localized overheating. At this temperature the fluid is 52F. below the initial temperature of its boiling range, and consequently re mains a liquid. Near its boiling point Aroclor 1248 tends to dehydrohalogenate to a very slight but measurable degree. If this occurs as a result of accidental over heating, the small amount of HC1 gas evolved tends to pass through the vent tank without harm to the equipment provided that the system is dry. Experimental observations using ideally-suited heat exchangers operating at a temperature of 650F. with imposed nitrogen pressures of 30 and 70 psig. showed that application of pressure did not prevent this small amount of thermal decomposition, which also occurs when the material is heated above 600CF. at atmospheric pressure. When heated continuously at 650F. under nitrogen pressure a gradual increase in the viscosity of the fluid occurs indicating that its service life would be limited to about 6 months to one year. Results of operating at 600"F., however, with out imposed nitrogen pressure indicate Aroclor 1248 can be heated continuously at this temperature for about 4 years before any viscosity increase could be expected to interfere with its pumpability at 50F. which is slightly below normal room temperatures. Provision should be made to prevent water contamination of the system. If the system becomes contaminated with water, any HC1 liberated by local ized overheating may dissolve in the water film which will float on top of Aroclor 1248 in the expansion tank. The acidic solution thus formed can cause corrosion. It is recommended that moisture be eliminated from the expansion tank by installing a moisture trap or by sealing the tank and applying 15 to 30 psig. of nitrogen gas. With exception of the expansion tank, the system should be kept full of Aroclor 1248 at all times to pre vent formation of air pockets where moisture may condense when the system cools off between periods of operation. Many years of practical operating experience have shown that Aroclor 1248 is virtually non-corrosive to valves, piping, tanks, and jackets made of cast steel, steel, or stainless steel. In actual use, brass valves have been used satisfactorily. 03*7Jll TOWOLDMONOQ30335 <A SAFETY of OPERATION Aroclor 1248 can be considered a non-flammable liquid: no fire point is obtained by the Cleveland Open Cup method on heating to its boiling point (650-F.). The spontaneous ignition temperature'2' is 1,299'F. In actual use. the following reported accident in a heating system demonstrates the fire resistance of Aroclor 1248 and the freedom it offers from the hazard of fire propagation. An operator's failure to start the circulation pump when the gas heater was on resulted in excessive coil temperatures. The line containing Aroclor 1248 sagged into the fire chamber. A weld rup tured and Aroclor 1248 poured into the red-hot fire chamber in contact with the flame. Dense smoke and fumes arose from the heater but there was no external fire. After the gas flame was cut off. the smoking stopped. Insurance authorities allow the use of Aroclor 1248 heaters in many locations with a minimum of protection. No fire walls are required to isolate the heaters. Aroclor 1248 has a low vapor pressure. In sys tems that employ a vented expansion tank, the loss due to evaporation is not measurable. If Aroclor 1248 in the expansion tank would reach a temperature of 266`F., the vapor pressure of the fluid would be onlv 1 mm. of Hg. SAFETY OF HANDLING Aroclor 1248 is an inert, unreactive liquid. If it is spilled on the skin, there are no noticeable ill effects. It is advisable, however, to wash the skin with soap and water after contact. A skin burn resulting from accidental contact with hot Aroclor 1248 should be treated in the normal manner for hot oil burns. Any liquid adhering to the burned area need not be removed immediately unless treatment of the burn demands it. If the burn must be cleaned, soap and water or repeated washings with a vegetable oil (olive oil) may be used. The vapors emitted by Aroclor 1248 heated to elevated temperatures are injurious on prolonged ex posure and should not be breathed. It is indicated that 2.0 mg. of Aroclor 1248 per cubic meter of air is the maximum safe amount permissable in workrooms. In commercial heat transfer installations, it is presumed that Aroclor 1248 will be used in a closed system free from leaks. Accordingly, there should be little or no opportunity for workers to come in contact with Aroclor 1248 vapors. A bibliography appears on page 32. TOWOLDMONOQ30336 design features Monsanto K4 HEATER The most significant factor to remember when selecting or de signing a heat exchanger for Aroclor 1248 use is this: Aroclor 1248 transfers heat while in liquid form, at the maximum recommended temperature of 600CF. for continuous operation, which is approximately 50'F. below the boiling point. Conse quently, Aroclor 1248 does not form sapor to accelerate convection circulation. Ordinary fire-tube or water-tube heaters which depend solely upon convection perform satisfactorily only at relatively low temperatures. When temperatures of 500-600F. are required, a forced circu lation type heater is recommended. A satisfactory type of heater design would consist of a specified number of tubes in parallel, properly orificed to provide a high velocity fluid flow of 8 to 10 feet per second. These should be spaced to permit uniform heat absorption throughout their entire length. A typical construction is shown in Figure 7. In its fabrication, the heater should be ASME Code all-welded construction, conforming to state and local ordinances. Tube joints, which in an ordinary steam heater would he the expanded type, must be sealwelded to prevent leakage. All connections larger than 3j" should be flanged connections, since ordinary threaded pipe connection is not suited for Aroclor 1248 service. Spiral-wound stainless steel and asbestos com bination is recommended for sealing joints and plugs. Drain valves should be installed at all low points on the heater and the valves must conform with ASME requirements for "blow down" valves. u 3s /3L 5 TOWOLDMONOQ30337 Since a heater operating on Aroclor 1248 is completely filled with liquid, costly liquid-level controls and condensate return pipes, fittings, traps, etc. are completely eliminated. Heaters can be provided with any desired kind of firing. Portable and small size stationary units are frequently elec trically heated; larger units may be gas- or oil-fired. In installa tions where an open flame presents a fire hazard, to meet insurance requirements the heater may be installed in a sepa rate building with piping carrying the hot Aroclor 1248 to the point of use. Properly constructed transmission pipes may ex tend for hundreds of feet. HEATER EFFICIENCY Forced circulation heaters with integral economizers will show an efficiency of from 75 to 80%. Heaters of the straight con nector type show efficiencies of 65 to 75%. depending upon the discharge temperatures. HEATER CAPACITIES Heaters using Aroclor 1248 (gas- or oil-fired) are available in output capacities ranging from approximately 250,000 Btu. per hour to large units rated over 10 million Btu. per hour. A heat flux density (or heat energy input) of approximately 5,000 Btu. per hour per square foot of tube surface is regarded as satisfactory. For lower output rate, electrically-heated units are favored, employing watt densities of 12 to 16 watts per square inch of element area. 034731* - 17 I r TOWOLDMONOQ30338 THE USERS The "users" or recipients of the heat at the point of processing can be any type of heating pan, platen, jacketed kettle, or coils of steel or stainless steel construction. Ordinary low pressure construction is satisfactory, since the pressure imposed on the Aroclor 1248 seldom exceeds 50 psig. In the user, however, it is important that all-welded construction be used. Threaded connections may allow leakage of the hot fluid. As in the heater, all connections %" and over should be flanged and all joints sealed with spiral wound stainless steel and asbestos gasket material. Alloy bolts should be used to secure flanges. A typical system with several users is shown in Figure 8. EXPANSION VESSEL FULL EXPANSION MANHOLE FOR REMOVAL Of SLUDGE MAKE-UP m** Figure ! 0 J< 7 3 TOWOLDMONOQ30339  (4 THEFUMF For most systems, cast-steel centrifugal pumps with waterC(K>Icd stuffing; box and bearings are to be preferred. However, high temperature centrifugal pumps with mechanical seals are now available which give excellent performance. In some in stallations. immersion pumps have been used. Whatever tvpe is selected, the pump capacitv and pressure head must be sufficient to circulate the volume of fluid at the rate the particular installation demands. To avoid shaft trouble and leakage at the seals, it is important to provide adequate expansion joints and to support the piping in a manner to avoid stresses on the body of the pump. Direct-connection pumps driven bv 1.750 rpm. motors are most commonly used. Each pump should be fitted with a positive differential control to switch off the burner in case of pump failure. When a new system is first put into operation, a slight leakage may be noticed at the pump. It is not advisable to tighten the pump gland, however, until the system has heated up close to the temperature of operation. PIPING LAYOUT The most important factors in the piping layout for Aroclor 1248 systems are (a) proper sizing for the required flow rate and (b) minimizing pressure drop, because the sys tem will undergo temperature changes, adequate expansion joints and loops to relieve expansion and contraction stress are essential. All pipe lines and connections should be of extra heavy or Schedule SO welded construction meeting A.S.M.E. require ments. Flanged joints should be used as sparinglv as possible to minimize potential leak points. All valves and controls should be cast steel construction with stainless steel seats. Pipe lines should be well insulated and those exjx)sed to temperatures below 70'F. should be steam jacketed. AH high points in the piping svstem should be provided with vent valves; all low points should have drain connections. Piping should be well anchored at frequent intervals, particu larly near expansion loops, to prevent vibrations. Figure 9 shows a typical piping diagram that illustrates the important features of an Aroclor 1248 piping system. These may be varied to suit the installation. 0347316 19 TOWOLDMON0030340 THE EXPANSION TANK The expansion tank should be large enough to accom modate about 20% of the total volume of the entire svstem, including the fluid content of the heater, piping, and all heatusers. Tank should be sized to be V<i-full when system is cooled to 70CF. and %-full when system is at maximum operating tem perature. Expansion tank should be fitted with a sight glass at the "full" range and a float-operated low-level switch to shut off burner in case of accidental fluid loss in the system. The expansion tank should be mounted on a platform high enough to support the liquid reservoir at least six feet higher than the highest point in the piping system. THE FEED and DRAIN PUMP To eliminate manual filling and draining of the heating system, it is recommended that a small 2-to-5 gpm. positive displacement pump be installed at some convenient point to pump the Aroclor 1248 into or out of the system. CONTROLS Controls for heating systems using Aroclor 1248 should be installed both on the heater itself and on the heat-using units. A wide variety of thermo-operating controls are available and any reliable standard equipment is satisfactory. Heater controls should be installed to regulate the firing mechanism in direct proportion to the required output. These controls should increase or decrease the heat in-put to main tain the Aroclor 1248 at the operating temperature required by the heat-demand of the user. Small units may be operated satisfactorily by relatively simple "on-off" or "high-low" con trollers; larger units may operate more uniformly if equipped with modulating temperature controls. User Controls should be installed to regulate the flow of the heat transfer fluid in direct proportion to the heat-con sumption of the heat-using equipment. In a multiple-user sys tem, separate controls should be installed on each consuming unit, to assure the proper heat-delivery. Safety Controls. In addition to activating controls, the heater must also be fitted with the proper safety controls to meet the A.S.M.E. requirements. Safety controls should include: 1. A high temperature limit control operating at the heater outlet to shut off the burner in the event of an excessive temperature rise. 2. A suitable low-limit temperature control to hold the burner at low fire until the Aroclor 1248 in the system reaches a temperature level of 180F. The low limit temperature control is essential because the viscosity of Aroclor 1248 is rather high at normal room tem perature. To avoid localized overheating upon start-up, it is not advisable to apply full heat from the burner until all the fluid in the system has attained a viscosity that allows good flow and unimpeded circulation. Cold start-ups require slow up-heats. Burners should be equipped with automatic ignition controls and flame failure controls. In wide-range firing opera tions, an over-fire draft control will increase the economy of operation. Induced draft fans are another factor which should be considered as a means of avoiding the expense of high chimneys. Where they are needed throughout the system, good quality recording or indicating gauges should be installed. COOLING EQUIPMENT Where fast reduction of temperature is required, suitable air- or water-cooling installations may be used. If the cooler is to be a water-type unit, it is suggested that stainless steel tubing be used for the coils to avoid corrosion on the water side. If a cooler is installed in the system, low temperature limit con trols should also be installed to avoid excessive cooling that might raise the viscosity to the point of impeding the circulation in the system. 03<.73iV TOWOLDMONOQ30341 FILTERING EQUIPMENT When heating systems operated on Aroclor 1248 are run continuously near the recommended maximum temperature of operation (600"F.), it is advisable to provide a filtering device that can be attached to the drain line of the storage tank. In this way discrete particles of dirt that may get into the system can be filtered out periodically. This is an advisable maintenance step since it will eliminate the danger of dirt clogging the valve seats or lodging in parts of the control mechanisms. A small portable filter such as those manufactured bv Honan-Crane Corporation (Lebanon, Ind.) or Sparkler Manufac turing Company (Mundelein. 111.) is quite satisfactory. CONNECTIONS and GASKETS In a system operated on Aroclor 1248, welded connec tions are preferable; threaded screw connections should be avoided wherever possible. This precaution will minimize leaks with consequent make-up. All connections %" and over should be of the flanged type fastened with alloy bolts to prevent frozen connections. Steel connectors should be used for all instruments and controls. For gasketing, spiral wound gaskets of corrugated stainless steel and asbestos combination should be used on all flanged connections. TESTING and CLEANING THE SYSTEM When a new system has been installed, it is essential to test the entire system hydrostatically for leaks, and to wash out all the lines to remove dirt, oil films, or pipe scale. Both the cleaning and the testing can be done in a single operation as follows: Fill the entire system with a water solution containing 5 pounds of soda ash and 5 pounds of caustic soda for every 1000 pounds (120 gal.) of water used. Thoroughly vent the sys tem at all of the highest points in the piping system to assure complete filling . . . then start the circulating pump. With the pump running, the entire system is next inspected for leaks. Next, turn on the burner at low-fire rate and raise the temperature of the wash solution to 180'F. This hot wash solu tion should be circulated continuously through the entire system (heater and all users) for at least 24 hours. At regular intervals a portion of the solution should be drained and replaced by fresh water. This partial draining should be continued at regular in tervals until the drainage from the system is clear. At the end of the 24 hour period, the temperature of the circulating wash solution should be brought up to 240"F. and the fire turned off. The whole system should then be drained and all vents in the piping opened. Residual heat will dry the pipes and the heater through the vents, which should remain open until inspection shows that the system is entirely dry. When all traces of water have dried out, the drains and vents are closed. Aroclor 1248 is then charged into the cleaned, dry sys tem. The circulating pump is started and firing begun at low heat until the Aroclor 1248 has reached a temperature of 2-50'F. Periodically during this initial up-heating, the lines should be vented every 10-15 minutes for at least two hours to allow any residual moisture or air to escape. After it is certain that all moisture has been eliminated from the system, the entire system should be inspected for leaks with the pump circulating the hot fluid. As a final inspection, the expansion tank should be checked to make sure that the tank is V4 full. After this, the burner can be set to full-fire and the system brought up to operating tem perature. When the temperature of operation has been reached all controls should be checked and adjusted so that the burner is regulated for full modulation. When the system is brought to full operating temperature, all pipe lines should be given a final inspection for expansion and bracing. 03*17318 TOWOLDMONOQ30342 GENERAL RECOMMENDATIONS for Operation and Maintenance The following recommendations are primarily guides for the manner of using Aroclor 1248 in an operating system. They are supplemental to the equipment manufacturer's own recommendations for operation and maintenance that relate to die heaters or the heat-using installations themselves. The recommendations for start-up, shut-down, precautions in event of power failure, and periodic check-ups on the fluid and equip ment apply as generally accepted practice on all types and sizes of systems. By following these recommendations, the troublefree service life of the heat transfer fluid will be increased. START-UP When systems have been shut down for week-ends or over-night and the fluid is cooled to room temperature, follow this start-up procedure: 1. Start the circulating pump and check the expansion tank to make certain the Aroclor 1248 is at the proper cold-start level {Tank should be %-full.) 2. Start burner at minimum flame setting and continue full circulation until Aroclor 1248 is heated to 180 F. when measured on the return side of the heater. 3. Turn heater up to full heat. SHUT-DOWN The following procedure will eliminate overheating of the fluid when shutting down: 1. Shut off burner completely with circulating pump still oper ating. Continue to run the circulating pump at full head for at least Vz hour to dissipate high residual heat in the com bustion chamber of the burner. 2. Shut off circulating pump at the end of Vz hour and switch off all heater electrical controls. PRECAUTIONS IN COLD WEATHER When heat exchanger is exposed to ambient tempera tures below 50F.. it is recommended that unit not be shut down. It is recommended that the burner be turned low and the fluid circulated continuously at about 200F. The unit will then be "at ready" for immediate high temperature operation. PRECAUTIONS IN CASE OF POWER FAILURE In case of power failure, the burner circuit is interrupted by the heater controls. When power comes on. the circulating pump should first be run for a few minutes to eliminate any vapor pockets that might have been formed by the fluid's being held static in the hot combustion chamber. If there is no knock ing in the piping system, full-fire may be resumed immediately, if the fluid temperature is above 180F. PERIODIC CHECK-UPS The regular maintenance inspection schedule should include the equipment manufacturer's recommendations and also inspection of the heat transfer fluid. The following is a listing of check points. 1. Lubrication of moving parts. 2. Operating fidelity and accuracy of readings of safety controls and temperature limit controls. 3. Inspection of heater tubes, burner, refractory linings. 4. Periodic cleaning of heater surfaces. 5. Inspection of water cooling at the circulating pump. 6. Regular repacking of stuffing boxes according to the manu facturer's recommendations. 7. Semi-annual or annual sampling and analysis of Aroclor 1248. Under normal operating conditions not affected by fre quent power failures or accidental overheating, when Aroclor 1248 is operated at 600F. it should not be necessary to check on the condition of the fluid more often than once or twice a year. The analysis for fluid condition is a simple determina tion of viscosity. The information given in Figure 6 serves as a guide to estimate the condition of the fluid, according to vis cosity values. Most users do their own testing; some have the viscosity determination made bv an outside laboratory. Customers can have their fluid tested by Monsanto free of charge. A one-quart sample is required, and sample should be carefully packed to avoid breakage in shipment. Samples should be shipped to: Monsanto Chemical Company Organic Chemicals Division Industrial Fluid Sales St. Louis. Missouri ABOVE INFORMATION APPEARS ON POCKET CARDS INSIDE BACK COVER 0JS7114 TOWOLDMONOQ30343 Designing or purchasing equipment for a heating system to be operated with Aroclor as a medium to deliver heat into a process requires consideration of heat transfer characteristics of both the user and the heater. The actual heat which can be absorbed by a user, for example, depends upon the over-all heat transfer coefficient, heat transfer area, and a mean ternperature difference between Aroclor and the material being heated. Both overall heat transfer coefficient and mean temperature difference are. in turn, affected by the flow rate of the Aroclor. This inter-relation of flow rate, heat, and temperature is usually solved by a trial and error procedure as covered in standard reference texts. The approach of Granetp) may be used to minimize or eliminate trial and error. The following tables and graphs of physical properties and engineering data are provided as an aid in layout and design calculations for systems to be operated with Aroclor 1248 as a heat transfer fluid in the liquid phase. Table IV lists properties useful in heat balance calculations bv which the flow rate is related to the heat transferred and the temperature change of the Aroclor. This relation is also shown graphically in Figure 10. The over-all heat transfer coefficient for the heater or user may be estimated by the methods outlined in the texts of McAdams(4) or Kern('1). This is usually done by combining the individual film coefficient of the Aroclor with other coefficients and conductivities to yield the over-all coefficient. Table V contains physical properties of Aroclor as a function of temperature which are needed for calculating the Aroclor film coefficient. Table VI gives typical film coefficients for Aroclor flowing through a 0.81 inch i.d. tube. These arc listed as a function of temperature and flow rate in a tubular heat exchanger. Other tube sizes would, of course, require a correction for the diameter in the Reynolds and Nusselt group of the equation (from McAdams) given at the top of Table VI. Correlations for estimating film coefficients for various materials that might be processed by indirect heating may be found in the texts cited (4). (r`) and elsewhere in the literature. For sizing pipe lines and pumping requirements. Figure II shows pressure drop vs. flow rate and pipe size for Aroclor 1248 at temperatures over 300'F. Above this temperature Aroclor 1248 flows freely like water. A bibliography appears on page 32. 0347320 : I j [ * \ l \ I * | f } jl ! ; i \ \ ' t 'i f j TOWOLDMONOQ30344 TABLE IV (( THERMODYNAMIC PROPERTIES OF AROCLOR 1248 Temperature 6F. C. 32 0 40 4 50 10 60 16 70 21 80 27 90 32 Jn0o0 38 43 120 49 130 54 140 60 150 66 160 71 170 77 180 82 190 88 200 93 210 99 220 104 230 110 240 116 250 121 260 127 270 132 280 138 290 143 300 149 310 154 320 160 330 166 340 171 350 177 360 182 370 188 380 193 390 199 400 204 410 210 420 216 430 221 440 227 450 232 460 238 470 243 480 249 490 264 500 260 510 266 520 271 530 277 540 282 550 288 560 293 570 299 580 304 590 310 600 316 610 321 620 327 630 332 Enthalpy Btu./lb. 0.000 2.162 4.881 7.616 10.367 13.134 15.917 18.716 21.531 24.362 27.209 30.072 32.951 35.846 38.757 41.784 44.727 47.686 50.661 53.651 56.657 59.679 62.717 65.771 68.841 71.927 74.029 77.147 80.281 83.431 86.597 89.779 92.977 96.191 99.421 102.667 105.929 109.206 112.499 115.808 119.133 122.474 125.831 129.204 132.593 135.998 139.419 142.856 146.309 149.778 153.262 156.762 160.278 163.810 167.358 170 922 174.502 178.098 181.710 185.338 188.982 Cp (Spec. Heal) Btu./lb./eF. 0.2695 0.2711 0.2727 0.2743 0.2759 0.2775 0.2791 0.2807 0.2823 0.2839 0.2855 0.2871 0.2887 0.2903 0.2919 0.2935 0.2951 0.2967 0.2982 0.2998 0.3014 0.3030 0.3046 0.3062 0.3078 0.3094 0.3110 0.3126 0.3142 0.3158 0.3174 0.3190 0.3206 0.3222 0.3238 0.3254 0.3269 0.3285 0.3301 0.3317 0.3331 0.3349 0.3365 0.3381 0.3397 0.3413 0.3439 0.3445 0.3461 0.3476 0.3492 0.3508 0.3524 0.3540 0.3556 0.3572 0.3588 0.3604 0.3620 0.3636 0.3652 Density Lbs./cu. ft. 91.6 91.3 90.9 90.6 90.2 89.8 89.5 89.1 88.8 88.4 88.1 87.8 87.4 87.0 86.6 86.2 85.9 85.6 85.2 84.8 84.4 84.1 83.7 83.4 83.1 82.9 82.6 82.3 81.9 81.6 81.2 80.9 80.6 80.2 79.8 79.4 79.1 78.8 78.5 78.2 77.9 77.6 77.2 76.8 76.4 76.1 75.7 75.4 75.0 74.7 74.4 74.1 73? 73.4 73.0 72.7 72.4 72.0 71.7 71.4 71 0 Ibs./gal. 12.22 12.19 12.13 12.08 12.03 12.00 11.96 11.91 11.87 11.82 11.77 11.73 11.69 11.64 11.58 11.53 11.47 11.42 11.38 11.34 11.29 11.24 11.18 11.14 11.10 11.06 11.03 10.98 10.94 10.90 10.85 10.81 10.76 10.71 10.67 10.62 10.57 10.53 10.48 10.43 10.39 10.34 10.30 10.25 10.20 10.16 10.11 10.06 10.02 9.98 9.94 9.90 9.85 9.80 9.76 9.71 9.67 9.63 9.58 9.53 9.48 Specific Gravity 1.47 1.46 1.455 1.45 1.445 1.40 1.432 1.425 1.420 1.414 1.409 1.404 1.400 1.493 1.387 1.381 1.375 1.370 1.365 1.359 1.353 1.348 1.342 1.336 1.331 1.326 1.321 1.316 1.311 1.305 1.300 1.296 1.291 1.286 1.280 1.274 1.269 1.264 1.259 1.253 1.248 1.243 1.237 1.231 1.225 1.220 1.214 1.208 1.202 1.196 1.191 1.186 1.180 1.175 1.170 1.165 1.160 1.155 1.150 1.144 1.138 Absolute Viscosity in Centipoises 850 380 200 115 66 47 32 24 18 14 11 9.1 }' 6.. 5.2 4.4 3.9 3.35 3.00 2.68 2.38 2.08 1.96 1.82 1.68 1.58 1.46 1.42 1.30 1.22 1.15 1.10 1.05 1.00 0.96 0.91 0.87 0.84 0.80 0.76 0.73 0.71 .068 0.65 0.61 0.60 0.57 0.55 0.53 0.51 0.49 0.47 0.45 0.43 0.42 0.40 0 39 0.37 TOWOLDMONOQ30345 FLOW RATES FOR AROCLOR 1245 TOWOLDMONOQ30346 c. 0 4 10 16 21 27 32 38 43 49 54 60 66 71 77 82 88 93 99 104 110 116 121 127 132 138 143 149 154 TABLE V THERMODYNAMIC PROPERTIES of AROCLOR 1248 P RANOTL Absolute Viscosity Hr. Ft. V Thermal Conductivity Btu. Ft. Hr. "F. Cpm l> 1_____J Temperature F. C. Absolute Viscosrty Lbs. Hr. Ft. k Thermal Conductivity Btu. Ft. Hr. F. 2060 960 485 278 160 114 77.5 58.0 43.5 33.8 26.6 22.0 18.2 15.2 12.6 10.6 9.45 8.10 7.26 6.48 5.76 5.03 4.75 4.40 4.07 3.83 0.0577 .0576 0.575 .0574 .0573 .0572 .0570 .0569 .0568 .0566 .0565 .0564 .0563 .0562 .0560 .0559 .0558 .0557 .0555 .0554 .0553 .0552 .0550 .0549 .0548 .0547 .0546 .0544 .0543 9844 4430 2353 1361 789 566 388 293 221 173 137 115 95 80 67 57 51.1 44.1 39.8 35.9 32.1 28.2 26.8 25.1 23.4 22.2 39.5 28.7 22.3 17.9 14.4 12.6 10.8 9.7 8.7 7.88 7.15 6.68 6.18 5.78 5.38 5.05 4.83 4.55 4.36 4.18 4.00 3.81 3.73 3.63 3.53 3.45 320 160 3.53 .0542 330 166 3.34 .0541 340 171 , 3.14 .0540 350 177 2.95 .0539 360 182 2.78 .0537 370 188 2.66 .0536 380 193 2.54 .0535 390 199 2.42 .0534 400 204 2.32 .0532 410 210 2.20 .0531 420 216 2.10 .0530 430 221 2.03 .0529 440 227 1.93 .0527 450 232 1.83 .0526 460 238 1.76 .0525 470 243 1.71 .0524 480 249 1.64 .0523 490 254 1.57 .0521 500 260 1.51 .0520 510 266 1.45 .0519 520 271 1.38 .0518 530 277 1.33 .0516 540 282 550 288 1.28 .0515 1.22 .0514 560 293 1.18 .0513 570 299 1.13 .0512 580 304 1.09 .0510 590 310 1.04 .0509 600 316 1.01 .0508 Cp/t k 20.6 19.6 18.5 17.5 16.7 16.1 15.4 14.8 14.3 13.7 13.1 12.7 12.3 11.7 11.3 11.0 10.7 10.3 10.0 9.67 9.26 9.00 8.72 8.36 8.14 7.85 7.63 7.33 7.16 [* 3.35 3.29 3.22 3.15 3.08 3.04 2.99 2.94 2.90 2.85 2.80 2.76 2.73 2.68 2.64 2.61 2.58 2.54 2.51 2.46 2.43 2.40 2.37 2.34 2.31 2.28 2.25 2.22 2.20 0 3<# 7it 3 TOWOLDMONOQ30347 HEAT TRANSFER DATA for AROCLOR 1248 FILM COEFFICIENTS pn-| ro g-] 02 rcD/ri 0.4 L81J* 0 023 J Lk J (Me Adams; Based on flow through 0.81" I. 0. tibo (1* 0. 0. x 13 ga.) expressed in Bti/si ft/hr./'F. FLOW RATE. 6PM. -- F. 1.0 2.0 3.0 i 150 ........ | ........ 200 44.9 63.4 250 33.5 58.5 80.9 300 40.5 70.1 97 350 45.3 79.0 109 400 49.0 85.5 118 450 53.3 93 128 500 56.3 98 136 550 60.5 105 145 600 64.2 112 155 4.0 78.7 102 122 137 149 162 171 183 195 5.0 ........ 94.0 122 146 164 178 193 204 219 233 6.0 83.2 109 141 169 190 206 224 236 253 269 7.0 86.2 124 159 191 215 232 253 267 286 305 -- 8.0 9.0 93.8 103 138 151 177 195 212 233 239 262 259 284 282 309 297 327 319 350 339 373 10.0 114 164 212 254 286 309 336 356 381 405 11.0 123 179 229 274 309 334 363 383 4,1 437 12.0 130 191 245 294 331 358 388 411 441 469 Calculations for other pipe sizes can be made using the data found in Tables IV and V. l No film coefficients were calculated for flow rates where the Reynolds number was less than 2100. i i 0 3 < ,7 3 ? < , I TOWOLDMONOQ30348 HEAD LOSS, FT. PER 100 FT. 30,000 FRICTION LOSSES LN SYSTEM PIPING AROCLOR 1248, ABOVE 300 F. | i O'* A f TOWOLDMONOQ30349  TYPICAL HEATERS USING AROCLOR 1248 <k A 200,000 Btu. (right) and a 300,000 Btu. heater, both gas-fired, have been in use at Monsanto for over 14 years for organic chem icals reactions. The heaters have operated near 600F. with the same charge of Aroclor 1248 for periods of 7 years. 03<,73^b 29 TOWOLDMQN0030350 A Taber submerged pump An insulated Aroclor return line A non-insulated vent line . An Aroclor drain port _ Fenwal maximum temperature safety control connected to solenoid valve in gas line Pressure gage Vent stack diagonal take-off The gas control valve to the burner is behind the solenoid valve Inlet from Taber pump line Aroclor outlet from cooler The Aroclor outlet from the cooler ties into the main line above the picture (Optional) A steam outlet from the coil to a steam trap with a bypass around the trap (Optional) A steam inlet line leadrng to a steam coil inside the reservoir for heating cold Aroclor. Coil return flange and bends Areelor Heitor Each heater consists of fire brick-lined walls and bottom inside a steel shell with steel baffles to force the hot combustion gases over the Aroclor coif for three passes. The top is a steel plate. Channel iron supports to raise the bottom of the heater above floor level Supports for cooler Right side water outlet Left side water inlet Cooler: Two-stage shell and tube construction with the Aroclor 1248 on the outside of the tubes. The two-stage cooler is piped so that one stage can be used on each Aroclor heater or both stages can be used on either Aroclor heater. 30 TOWOLDMONOQ30351 . RIGHT ( - A 40.000 Btu. per hour electrically heated portable heat exchanger used to heat vessels of about 50 gallons working capac ity. This unit was built for a variety of small scale chemical reactions. It was initially designed to vaporize approxi mately 200 lbs. hr. of an organic com pound which has a heat of vaporization of 150 Btu. per pound; a 30% heat loss was allowed for. Experience with the heater indicates that a horizontal rather than the vertical mounting of the immer sion heater (at operator's left) would have been more satisfactory. FAR RI6HT A 4.000.000 Btu. hr. forced circulation International LaIVtont heater. RIGHT Control panel for a 3.000.000 Btu./hr. International laMont heater that oper ates the 3,500 gallon, glass-lined kettle shown on the left. This kettle is the :is largest of its kind in the United States. FAR RIGHT Commercial heaters operating on Aroclor 1248 are available in any capacity desired. This is a 1.200,000 Btu. hr. installation. | I I i i l Oi'tTid'i 31 TOWOLDMONOQ30352 (PHoto Courtesy Union Iron Works) FAR LEFT A pilot plant resin processing vessel operated on indirect heat transferred by Aroclor 1248. Vessel and heater are mounted together in one unit. LEFT This 500,000 Btu. hr. forced circulation heater is electrically heated and designed for a liquid temperature of 500 'F. The construction is similar to a double pipe heat exchanger with the electric heating elements in the inner pipe; the Aroclor 1248 circulates through the annular space between inner and outer pipe. The liquid Aroclor 1248 is delivered from the heater at a temperature of 500F. and heats the contents of a jacketed kettle with a batch capacity of 1,000 gallons. This design for a forced cir culation heater was de veloped by Cleaver Brooks Company, 1JTKK V! t ill (III I) 1. Monsanto Chemical Co., St. Louis. Mo., Application Data Bulletin O-P-115 (1954). 2. Sullivan, M. \ .. Wolle. |. K., and Zisrnan. W, A.. 'Indus. Eng. Chern.," 39. I60T (1947). ^ 3. Grain I., Heat Transfer Performance' Curves', Chemical Engineering P. IS7-I90. March, 1935. 4. McAdams, W. II., "Ileaf-Transmission". McCraw-Ilill Book Co.. Inc., \cw York. ( 1942). 5. Kern, D. (^., "Process Heat Transfer". McGraw-Hill Book Co., Inc.. New York? (1950). t: i 1 ( i f TOWOLDMONOQ30353 POCKET CARDS SUMMARIZING INFORMATION ON PAGE 22 aroclor LIQUID HEAT TRANSFER MEDIUM ! For temperatures up to 600F. Long-lasting, trouble-free service Fire-resistant, non-corrosive Operates in un-pressured, minimum cost equipment Monsanto supplies Aroclor 1248. but not the heat exchangers. Monsanto will be happy to recommend sources of supply. 0347330 j | | E I i j II TOWOLDMONOQ30354 MONSANTO CHEMICAL COMPANY Regional Offices: ATLANTA BOSTON CHICAGO CINCINNATI CLEVELAND DETBOIT HOUSTON LOS 4NCKUES NIWilORK SAN FBANCISCO ORGANIC DIVISION ST. LOUIS, MO. SEATTLE ST. LOUIS MINNEAPOLIS-ST. PAUL WILMINCTON 0 3 A / J JI t TOWOLDMONOQ30355