Document KRmjk8QeweQB1RN0oE8gLg9k2

t 'i; mm CO NTENTS, History of Indirect Hooting with A 1243 2 Advantages of Arodor Heating 4 Description of Arodor 1248 Table I -- Physical Piopi .performance Qualifier of Arodor 1246 .., Characteristics of a'Typical Heater ' Heater System Component! Piping and Control Circuits The Complete Hooting Circuit with Multiple Users What Indirect Heating with Arpclpr Pg#V, . ; : Summary of Beneflte from / , Indirect Heating-with Arod^'1248 f 3 33 ife- `Registered Trade Mark for Monsanto's family of > chlorinated ptoolyphhetnnyl compound!. Arcelor 1248;./. .^r , it the one most suited for,*Indlrert., beatings. <. applications. \ ,,} . . 'W' `.'W ~< 'i ' *" USLHlZt TOWOLDMON0038304 WATER_PCB-00022773 FIRE-RESISTANT INDIRECT HEATING \'.X 2 W5 Gftas&3 Aroclor0 1248 is fire-resistant, It does not support combustion up to its boiling range, 652-725 F., and has a high flash point 380 F. Thus indirect heating with Aroclor greatly reduces plant fire hazard, thereby increasing worker safety and possibly preventing costly fire damage to plant and equipment. Aroclor is used in the liquid phase at atmospheric pressure or at low pressures, and does not require costly high pressure equipment. Explosion hazard is eliminated. Forced circulation indirect heating with Aroclor is efficient and uniform. It gives accurate control of heat put into the process. This often leads to increased production, lower costs, and better quality of the finished product. The general purpose of this booklet is to assist you in evaluating the benefits of using Aroclor for indirect heating in your plant or processes. TOWOLDMON0038305 WATER_PCB-00022774 HISTORY OF INDIRECT HEATING WITH l In 1941, certain new manufacturing processes of the Mon santo Chemical Company required using a noncombustible heat transfer medium at pressures of 30 pounds per square inch or less and temperatures in the range of 500 to 600 F. Monsanto's Aroclor 1246 was the only commercial and economical material which met these requirements. Complete success in operating these early heaters using Aroclor created more general interest in the benefits of a high temperature, fire-resistant, heat transfer agent for a variety of industrial applications. Also about this time, heating design engineers had begun to advocate in this country the benefits of liquid phase high temperature heating. Subsequently, leading manufacturers of heating equip ment began to build heaters constructed specifically to accomplish maximum efficiency and maximum operating temperature using Aroclor liquid. TOWOLDMON0038306 WATER_PCB-00022775 A PARTIAL LIST OF PRESENT COMMERCIAL AROCLOR HEATING APPLICATIONS INCLUDES: 1. Heating chemical process equipment, especially where flamma ble materials are handled. 2. Processing varnishes and resins. 3. Molding plastics and rubber materials. 4. Heating bituminous materials. 5. Heating vegetable oils for deep-frying potato chips and other food processing operations. 6. Processing titanium and other metals. 7. Indirect heating in the manufacture of dyestuffs. 8. Heating corrugating rolls. 9. Indirect heating of distillation equipment, 10. Heating panels for continuous vacuum belt drivers, To assist industry with installation of indirect beating systems using Aroclor, a handbook entitled, "Aroclor 1248 Heat Transfer Data", giving engineering data is available from Monsanto. In addition, the names of leading heating design engineers and manufacturers who build heaters for Aroclor will be supplied when desired. Monsanto does not manufacture or supply equipment for heating with Aroclor. TOWOLDMON0038307 WATER_PCB-00022776 SIMPLICITY The heaters are characterized by simplicity of construction and operation. There is no vapor formation and consequently no traps, feed pumps, etc. to maintain. An open vented tank permits free expansion of the fluid and avoids all problems of feed regulation, vacuum systems, or condensers. ACCURACY OF CONTROL Arcurate temperature control for heating and cooling is provided. CONVENIENCE Aroclor heating units are compact, space saving and may be fired with gas or oil or heated electrically. Convenient controls for safety and tem perature regulation are provided. The viscosity of the fluid permits pump ing at room temperatures. QOU127 TOWOLDMON0038309 WATER_PCB-00022778 v*f.\ .DESCRIPTION i ' , fit* Aroclor 1248 is a practically colorless mobile liquid at room temperature. It is essentially tetrachlorobiphenyl with very small amounts of both lower and more highly chlorinated biphenyls. PHYSICAL PROPERTIES OF AROCLOR 1248 m. 6 Appearance Absolute density, g./ml. Absolute viscosity, centipoises Practically colorless mobile liquid " 1.44 30 1.41 60 1.37 100 1.27 200 1.17 300 86 140 212 392 572 ! 112.0 17.5 4.2 0.99 0.47 30 60 100 200 300 86 140 212 392 572 Thermal Conductivity, li.t.u./hr./sq. ft./0 F./ft. Specific Volume, ml./g. Specific Heat, cal./g./ C. Vapor Pressure, mm. Hg Dist. Range, ASTM D-20, Flash Pt., Cleve. Open Cup, ASTM, D 92-45, Fire Pt., Cleve. Open Cup, ASTM, D 92-45 Pour Pt., ASTM, D-97, Coef. of expan,, ml./ml./0 C (25-65 C.) 0.0571 0.0564 0.0555 0.0534 0.0512 0.696 0.709 0.728 0.787 0.860 0.283 0.297 0.326 0.355 0.00037 0.16 2.9 18.0 360.0 None 0.000702 30 60 100 200 300 30 60 100 200 300 50 100 200 300 37.8 100 150 200 300 345-385 | 193-196 I : 86 140 212 392 572 86 140 212 , 392 572 ' 122 212 392 572 100 212 302 392 572 652-725 379-384 -7 i i 'J 19.4 ' Additional physical conitanti and utoful #ngtn*rlng data and datalli or* glvon in th handbook, "Aroclor 1248 Hat Tramfor Data". 06141^8 TOWOLDMON0038310 WATER_PCB-00022779 LIQUID PHASE LOW PRESSURE 600 F. MAXIMUM Aroclor 1248 is used in the liquid phase at atmospheric pressure or not over 20 to 30 PSI gauge and up to a maximum continuous operating temperature of 600a F. HIGH BOILING FLUID The maximum operating temperature is sufficiently below the 652-725 F. boiling range of Aroclor 1248 to assure a liquid condition at all times. EXCELLENT HEAT STABILITY Although Aroclor is very stable to heat, adequate forced circulation, (about 20 to 80 gpm depending on the size of the system) should be provided to protect the liquid against localized overheating. Fluid velocity should be about 5 to 8 feet per second. FORCED CIRCULATION AVOIDS LOCALIZED OVERHEATING Brief overheating may not be harmful but extended heat injury above 600 F. will result in an increase of viscosity and measurable dehydrohalogenation. TIGHTLY CLOSED SYSTEM ELIMINATES VAPOR LEAKS AND ODOR With the exception of an open vented expansion tank, the system must be completely closed and sealed tightly to prevent vapors and odor from entering workroom areas. RY AND FULL SYSTEM ELIMINATES OSSIBLE CORROSION The system should be kept dry and free from moisture. It is desirable to keep the heater and piping full of Aroclor liquid at all points. This eliminates spaces where moist air might collect during shutdown periods. By following these simple precautions, possible corrosion is minimized or eliminated. 061^129 7 oa TOWOLDMON0038311 WATER_PCB-00022780 I CHARACTERISTICS OF A TYPICAL HEATER TAILORED TO FIT THE JOB Heating equipment using Aroclor is selected or designed to meet the requirements of the process, whether it is large or small. The heating equipment Tanges in size from small portable units which are usually electrically heated to large gas or oil fired units with capacities ranging from 250,000 to more than 10,000,000 B.t.u.'s per hour. ADVANTAGES OF FORCED RECIRCULATION HEATERS Especially in the case of large size heaters where the maximum operating temperature of 600 F. is required, the forced recirculation heater is superior to any heater dependent on natural circulation. The forced circula tion system is engineered to give a positive, uniform fluid flow through all tubes fed from a header, whereas natural circulation units have no special design to equalize the flow in the heater tubes. Where natural circulation units are operated with thermal liquids, it is impossible to distribute the flow equally through all tubes. The thermal liquid seeks the shortest route to the discharge outlet. Consequently, the longer tubes, because of their greater resistance to flow, are subject to overheating. This becomes an important consideration when such units are operated at the high temperature range prescribed for a given fluid and may result in decomposition of fractions of the thermal liquid. Also, since the discharge temperature from the circuit through a natural circulation unit is the average temperature of the short-circuited fluid and the overheated fluid from the longer tubes, this causes variable temperatures which are produced at the heater outlet. 8 0614130 TOWOLDMON0038312 WATER_PCB-00022781 \\\\\\ UNIFORM TEMPERATURE Forced recirculation thermal liquid heaters, which consist of groups of small diameter tubes of equal length and orificed for uniform flow, provide even temperature distribution through all tubes in the circuit. Small diameter tubes, which are not practical in natural circulation heaters because they limit capacity, have a distinct advantage in forced recirculation units. In the smaller tubes the volume of fluid from the surface film to the center of the tubes is less and therefore heating is more uniform than in larger diameter tubes. The forced recirculation heater is designed to move the fluid at velocities of 5 to 8 feet per second. This high velocity and resulting turbulence, coupled with the small fluid content of the tubes assures high rates of heat transfer and extremely close control of the outlet temperature. Tolerances of plus or minus 2 F. or closer are possible. ELIMINATES SLUGGISH FLOW Forced circulation eliminates dead spots or sluggish flow areas where localized overheating of the Aroclor may occur. 061^131 I TOWOLDMON0038313 WATER_PCB-00022782 HEATER SYSTEM COMPONENTS f TK nxt four pog doicribo tho main foaturot of th* lypitpl piping diagram hown on pogot 14 and 15. A ivmmotion of primary advantage of hoofing with Arodor 1248 thon follow*. THE HEATER FLOW CIRCUIT The flow circuit consists of a thermal liquid heater and a recirculation pump which discharges the fluid returned from the system into the upper header of the heater as shown in Figure 1 THE PUMP All Aroclor heaters are designed to avoid direct flame impingement on the tubes. The recirculation pump may be any one of a number of standard centrifugal units designed for hot liquid service. The pump should be made of cast steel and have a water-cooled stuffing box and water-cooled bearings. The stuffing box should have room for at least eight rings of packing and a lantern ring. Durametalic No. D-110 or Garlock No. 234 may be used for packing the pump. Mechanical seals have also proved to be successful at elevated temperatures. An open non-overloading impeller is desirable, as it will handle the cool, more viscous liquid on starting the system better than a positive displacement type pump. THE BURNERS Gas and light-oil burners are usually used. Heavy oil burners using bunker "C' oil usually require furnishing steam to preheat the oil. INDUCED DRAFT FAN As an economy feature to eliminate the expense of building and main taining a high chimney, the heater is usually fitted with an induced draft fan. The products of combustion are discharged from the fan into an exhaust vent higher than surrounding buildings. 10 061A132 TOWOLDMON0038314 WATER_PCB-00022783 FIG. 1 THE PIPING AND CONTROL CIRCUITS PIPING A typical heater piping and control circuit is shown in Figure 1. All piping larger than ft-inch i.v Hanged or welded; experience bus shown that hot Aroclor penetrates screwed joints of larger sizes. Steed anti cast steel are used throughout. Spiral wound stainless steel and asbestos gaskets are recommended for all connections. For operation in areas whore the Aroclor temperature may drop so low as to make the fluid unusually \ Aeons, it MMS' be desirable to steam jacket the Aroclor circulating lines to facilitate rapid start-up in cold weather (or "when needed"). Suitable safety provisions such as safety pop-ofT valves, must he installed in the steam jacket system to prevent pressure ruptures which would develop if any condensate remained in a closed system during subsequent high tempcratiue operation. Qblii3 TOWOLDMON0038315 WATER_PCB-00022784 DIFFERENTIAL PRESSURE CONTROL SAFETY AND TEMPERATURE CONTROLS Connected to the suction and disc-harm* .sides of the pump, this device shuts off the burner in case of pump failure or a broken pipe line. Any factor causing a decrease from the desired operating pressure will activate this device to shut down the burner. TEMPERATURE CONTROL This unit modulates the burner in response to temperature variation of the liquid. FLAME FAILURE CONTROL An electronic flame control apparatus pilots the flame and stops the burner in case of unsatisfactory combustion. TEMPERATURE LIMIT CONTROL This contains thermocouples attached to discharge ends of the tubes at critical points. Excessive temperature rise induces the control to shut down the burner. PUMP MOTOR STARTER The motor starter should be furnished with an auxiliary switch. The auxiliary switch is on the burner circuit so that anv motor failure or short-circuit will stop the burner. 061413* TOWOLDMON0038316 WATER_PCB-00022785 1 LIQUID LEVEL CONTROL This should ho located at the highest point in the system, usually in the expansion tank. Its purpose is to shut off the burner in ease of a liquid level drop in the system such as would result from a pipe break or excessive leakage at the pump. AIR SAFETY SWITCH This control is applied to the suction side of the induced draft fan. Its purpose is to stop the burner in case of fan motor bum-nut or over heated bearings. VENT TANK The vent tank or expansion vessel is located at the highest point in the system and "floats" on the line. It is best connected to the intake side of the pump as this tends to give a positive head on the pump. The Aroelor in the vent tank should he relatively cool. It acts as a seal. However, the tank should be closed and fitted with a vent pipe and elbow with a moisture trap to keep out moist air. The capacity of this tank is nonnalK 25? of the volume of Aroelor in the system. COOLER A very useful adjunct to the system is a double pipe cooler on the outlet of the heater. By circulating water through the jacket, the Aroelor mav be cooled and the temperature of the system lowered. This is helpful when it is necessary to cool a batch before removing it or when an exothermic reaction requires control. 0614135 13 TOWOLDMON0038317 WATER_PCB-00022786 TOWOLDMON0038318 WATER_PCB-00022787 W\v drwlopments .Mill ii H'l'i \ i sr( I production ] cqnii tnnrnts in (In iIhiiikmI and process m dustrirs clrm.(in! lij^lirl 11 n i pcrat lire lieatmi', with safety, acciiracv and economy. Tempera tiiivs r<'t|uirc<I arc- no longer practical w ith steam due to the extreme pressures repined. costly ('i| nipi nr nl. ami e,\ 11 a t out m|s nrrdrd do inert indirect licatmu rc p i i i ei nents up to (>0(l Id, Arcelor 12 IS used in properly dcsiuned r([iii])iiient will do the ]oh accurately, elficienth. ectnirmic alis am 1 without tin hazards of fire or r\plosion. I he lieaters are of -impli eonstriictioii cm, In nperate and iiiallitain and leer com ]>a<tl!,-s m\es ''parr Indin'il hratinu, with Aroelor pis'es liiidik aeeui'ate temperature control. It simplifies proccss operations. increases production rates and low l 'VS costs 06H137 TOWOLDMON0038319 WATER_PCB-00022788 SUMMARY OF BENEFITS FROM INDIRECT HEATING WITH *48 TOWOLDMON0038320 WATER_PCB-00022789 1. Safety i join fire ami explosion. 2. Operating temperatures np to 600r in properly designed recireulation heaters. 3. Accurate and uniform temperature control. 4. Economy of heating, low cost nonpressuri/ed equipment, low niaintcnaiK`e. space savings. low fluid make-up. 5. IncreaM'd production In some processes, produelion rates were incvcivsed mmh as 50,;. 0. Product uniformity results from more accurate temperature control, .7 Reduced product cost results from better control of quality. 3. Heating and cooling in the same equipment. Q. Dill emit individually controlled temperatures at various user sta tions in the circuit gives flexibility. io. Simplicity of installation and oper ation. Chemicols Division, Post Office Bex 478, St use of Aroclor 1248 0619139 TOWOLDMON0038321 WATER_PCB-00022790 / Monsanto VI MONSANTO CHEMICAL COMPANY ORGANIC CHEMICALS DIVISION P. O. BOX 470 ST. LOUIS. MISSOURI Ob 1 WQ TOWOLDMON0038322 WATER_PCB-00022791