INDUSTRIAL and SCIENTIFIC

CONTINUOUS VISCOMETER In a typical refinery control laboratory, investigation has shown that approximately 300 determinations of viscosity are made per twenty-four hour day in order to control quality and specifications. Most of the determinations, about 90x, are made on lubricating oils with the balance on fuel oils, jet fuels, diesel fuels, hydraulic oils and various types of asphalts. While the percentage and total number of viscosity determinations may vary at each refinery, never- theless considerable time and effort is expended on laboratory tests. An instrument installed in the plant to record and/or control the viscosity of a stream would:

1. Decrease the costs of laboratory analyses.

`2. Provide rapid, accurate and continuous record and/or con- trol of viscosity for closer control of refining operations.

Various older designs of the Hallikainen CONTINUOUS VIS- COMETER have been field tested for over fifteen years and the pres- ent design for more than five years. This instrument has been suc- cessfully applied to miscellaneous refining streams, including:

1. Continuous Lube Oil Blending-In some instances the in- strument is used to monitor the final stream blended by a precision Modal 1077522

blender; in other instances, and with great success, the instrument itself is used ~1s 0 blending control instrument to control the blending of lube oils, fuel oils, etc.

2. Vacuum Tower Distillation -A CONTINUOUS VISCOMETER provides immediate information as to product output and thus enables tight control on product specifications. By continuously monitoring the tower output, the product may be directed to further processing without storage in hold-up tanks while a laboratory analysis is being performed.

3. Deosphalting - When scheduling requires CI change in product, CI CONTINUOUS VISCOMETER indicate:, the changes and allows accurate switching of tanks. In this mclnner product contamination is reduced.

4. Lube Oil Dewaxing-Many changes in feed stocks normally characterize the dewaxing of lubricants. It is desirable to recognize the change immediately in the product stream for minimum product degradation. A CON- TINUOUS VISCOMETER may be used to detect product changes.

5. Crude Oil Residuals-The blending of heavy vacuum tower bottoms and gas oil using ~1 CONTINUOUS VIS- COMETER eliminates the need for further tank blending and possible over-dilution.

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Figure 1 -Schematic Flow Diagram

6. Fuel Oil Production -A CONTINUOUS VISCOMETER is being used to control the blending of fuel oils. In this application, the closer control achieves a saving of 1 % of premium furnace oil from a fuel oil stream of 17,000 Bbls/day.

PRINCIPLE OF OPERATION

The Hallikainen CONTINUOUS VISCOMETER is primarily designed to measure the viscosity of Newtonian prod- ucts (fluids whose viscosity does not wry with sheor rate) such os lubricating oils, etc. The instrument moy be used to analyze non-Newtonian products (fluids whose viscosity varies with shear rate) if o viscosity determination at one shear rate will provide adequate information. The metering pump built into the instrument requires that the fluid to be measured have lubricating properties.

Figure 1 is o schematic flow diagram of the instrument. The externally mounted filter (supplied with the vis- cometer os standard equipment) is o large capacity Y strainer that provides o filtered sample to the instrument. A constant sample flow rate is achieved with the precision metering pump driven by a synchronous motor. The sorn- ple fluid then posses through a heat exchanger. It should be noted that the pump and capillary tube, as well os the heat exchanger, are immersed in o constant temperature oil bath. The tem,perature of this both is regulated to &.005"C. The sample fluid, now at constant temperature and constant volume, is forced to flow at o constant rate through o capillary tube. The pressure drop across the capillary tube is converted to o pneumatic or electrical signal that is a linear function of absolute viscosity (centipoise). A 60 mesh screen filter in front of the capillary tube (an optional part) is to protect the capillary against coke particles ttat might form in the heat exchanger. A relief valve protects the flow system against excessive pressure that might occur due to blockage of the capillary, etc.

The choice of capillaries and transmitters permits measurements to be made over o range of from 0 to 2500 centipoise at the both temperature. After installation and adiustment, the CONTINUOUS VISCOMETER requires very little attention.

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ACCURACY

The CONTINUOUS VISCOMETER has been thoroughly tested and proven. This Viscometer provides many years of reliable, trouble free plant use. Over-all accuracy of better than 1 % has been obtained in plant application.

DESCRIPTION

Housing-The oil bath and electronic controls are each contained in light weight aluminum explosion proof boxes suitabl& for use in Class 1, Group D, Div. 1 hazardous areas. The oil bath cover and box are insulated with Maranite and Fiberglas and enclosed in 16 gauge steel housings.

Motor-A `/a h.p. 115/230 v, 50/60 cycle AC synchronous, gearhead, explosion proof motor is flange mounted on the oil bath cover. The motor shaft extends through the top cover, driving CI precision metering pump and a bath stirrer through spur gears.

Pump-A precision gear pump, with critical parts machined to a tolerance of 25 microinches, provides a con- stant sample flow of 64 ml/minute for 60 cycle operation (approximately one gallon/hour). To further assure accu~- ate flow rates, the pump is lapped and run in at the factory before installation in the instrument. Because of the special attention given to the pump, it is recommended that replacement pumps be obtained from Hallikainen.

Heat Exchanger-The stainless steel heat exchanger has sufficient capacity to bring the sample to the viscosity measuring temperature.

Cooling Coil-A stainless steel cooling coil is provided in the oil bath for constant circulation of cooling water when and if required. The cooling coil will be used if'the desired control temperature is approximately ambient and/or if the inlet sample temperature is greater than the instrum!ent bath temperature.

Stirrer-Two stainless steel stirrers of special design (Hallikainen-Shell Jet Stir impeller) are used to agitate the bath oil, minimizing the over-all time constant and temperature gradients of the oil bath. The hollow blade stirrers cause the bath oil to flow radially out through the blades with CI high velocity as well as in directions nor- mal and tangential to their blade surfaces.

Capillary Assembly-The maximum viscosity range that may be measured by the CONTINUOUS VISCOM- ETER is 0 to 2500 centipoise (0 to approx. 1300 SSF @ bath temperature or 0 to approx. 13000 SSU @ bath tem- perature based on sp. gr. of 0.9). The capillary tube is selected to measure the viscosity of a fluid over Q particular range for a given measuring temperature. The range which may be covered by each capillary is determined by the range of the transmitter used. Each capillary is calibrated and clearly marked at the factory and an approximate calibration curve provided. The capillary assembly is designed so that it may be changed in one minute or less without the need for special tools.

Relief Valve-A stainless steel relief valve is placed between the capillary tube inlet and pump inlet, to pro- tect the instrument against excessive pressure due to the possible failure of the heaters, occidental starting of the pump before the bath has reached operating temperature, clogging of the system or the use of an incorrect capil- lary tube. The valve is set to open when the pressure exceeds 115 psi (on most models), causing the sample fluid to circulate through the metering pump. Viton "0" rings are used which are capable of withstanding tempera- tures of 450°F.

Filters-The instrument is provided with one Y strainer (see Figure 1) and one 60 mesh corrosion resistant screen filter [optional] located at the capillary inlet to prevent blocking of the capillary tube by particles which may have formed in the heat exchanger due to coking.

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The Y strainer is normally installed so as to be self cleaning. The Y strainer has cost steel body with 100 mesh stainless steel screen.

Oil Bath Temperature Control-The oil bath is temperature controlled by CI Hallikainen-Shell THERMOTROL Temperature Controller. The controller utilizes a fast-acting (0.8 seconds response time) resistance thermometer as 1 the sensing element. An electric heating element (tubular type immersion heater-1000 or 2000 watt) supplies the necessary heat.

The THERMOTROL Temperature Controller, incorporating proportional and reset control modes, is capable of controlling the bath medium to r!z.OO!X. of the desired both temperature. ISee separate brochure on the THERM- OTROL for additional details.) On the standard THERMOTROL, (photo at left) two ten-turn potentiometers ore used to adjust the desired oil both set point temperature. A decade switch which permits selection of five fixed temperature control points (e.g. 100, 122, 140, 180 and 21O'F., or any other combination of fixed temperatures) is available on special order (photo at right).

Sample Fluid Temperature Measure- ment-A special etched stem viscosity thermometer is provided to read the sample fluid temperature at the capillary discharge. It is inserted in the thermom- eter and capillary holder and positioned so that the bulb of the thermometer is directly above the capillary tube. I' I

Bath Box Lowered Page 4 Close-up of Inner Parts

Model 107754 Model 107757 VISCOSITY MEASUREMENT

Absolute viscosity in centipoise is directly proportional to the pressure drop clcross the capillary tube. Several types of transmitters are available to meawre the pressure drop across the capillary tube. The selection of a particular trans- mitter should be based on the following considerations:

1. When a pressure transmitter is used, only the pres- sure on the upstream side of the capillary is measured; the downstream side of the capillary is discharged to atmos- phere. Differential pressure transmitters are the more popu- lar type used. These transmitters meclsure the pressure drop clcross the capillary. With differential pressure transmitters, the sample may be pumped back into the sample line by the metering pump in the instrument.

Model 1077510

2. Chemical Seals for Transmitters-These ctre rec- ommended for most measurements, but definitely are re- quired where the sample is of a wax or pitch base and/or

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Model 107758 would have a tendency to congeal in the sample lines. The use of chemical seals is desired since the diaphragm of the sealed system contacts the sample in the temperature controlled bath and transmits the pressure measurement through the solidly filled chemical seal to the pressure measuring element in the trcms- mitter. Of lesser importance, but also of value, is the reduction of dead space occupied by the sample fluid when chemical seals are used. Steam tracing of pressure lines to transmitters without seals is available. ?

3. The transmitter output signal may be pneumatic or electric depending on customer preference.

4. The range and spon of the transmitter determines the range of a single capillary in absolute viscosity units or ceoti- poise. The viscosity range of o capillary can vary from a mini- mum ratio of 1.09 (maximum to minimum depending on process conditions) to infinity with o maximum range of o to 2500 ten- tipoise at the bath temperature.

5. Indicating or non-indicating transmitters may be sup- plied os listed in the following table.

Model 1077757/7 Model 1077Sl2

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Viscometer Model No. Transmitter Descriotion output Sianal Chemical S.4 Oil Bath Temtx Range Transmitter - 1077 Taylor TRANSAIRE Pneumatic Y-3 *Ambient to 240°F. PXSSUVS 107754 Microsen Type 145-3 Electric Yt?S *Ambient to 240°F. PreSSUre r- 1077% Taylor Type 226R Pneumatic - Yes *Ambient to 240°F. Pressure - 107757 Foxboro Type 13A - - Pneumatic No .- *Ambient to 24O'F. Diff. Pressure 107757I7 Two Foxboro 13A Pneumatic NO *Ambient to 240°F. __Diff. Pressure 1077S8 Foxboro Type 631-l Electric - Ye5 *Ambient to 240°F. Pressure 1077510 Swartwout P2T/4 Electric NO *Ambient to 240°F. Pressure - 1077512 Foxboro Tvoe 613 Electric NO *Ambient to 240°F. Diff. Pressure 1077513 Swortwout D2T Electric NO *Ambient to 24( 1°F. Diff. Pressure 1077S20 Honeywell 30310 Electric NO *Ambient to 240°F. Diff. Pressure 1077522 Taylor 213TD Pneumatic NO *Ambient to 240°F. Diff. Pressure 1077S26 Honeywell 29211 Electric NO *Ambient to 240°F. Diff. Pressure 1251 Taylor Type 206 Pneumatic YS?S *Ambient to 240°F. Diff. Pressure 1251S4 Honeywell 30210 Electric Yl?S *Ambient to 240°F. PreSSJre 125lS20 Taylor 225TN Pneumatic Yes tAmbient to 350°F. Diff. Preswre 1251525 Honeywell 738Nl-Cl Pneumatic Yes *Ambient to 240-F. Prf%XJre *Maximum Oil Bath Temperature may be increased to 300°F. by change in certain components. tWith transmitter specified and other modifications, units have been used to 350°F.

Model 1251525 Model 1251

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Exploded view capillary and thermometer holder for differential pressure transmitter instruments, show- ing capillary, capil- lary filter screen and thermometer. GENERAL SPECIFICATIONS Viscosity Range-O to 2500 Centipoise at bath temperatvre [or frac- tion thereof depending on transmitter range and span). Accuron/-1 % or better. Flow Rated+. ml/minute (approx. 1 gal/hrl for 60 cycle power supply. 50 ml. per minute for 50 cycle. Response Time-l.4 minutes (.B min. dead time and .6 min. time cc&ant). Special versions to as low as 15 second response time on special order. Inlet Pressure Limitations-5 to 500 psig. Inlet Temperature Limitations-Dependent on bath temperature may require external cooler. Materials of Construction-All metal parts in contact with the sam- ple are stainless steel except filter body. Oil Bath Capacity-Model 1077 _ 2% gallons Model 1251 - 5 gallons. Filter Ratings-External Y strainer with loo-mesh screen Capillary Filter - 60 mesh screen (optional). Sample Inlet Connection--`/," FPT Sample Outlet Connection--On Models 1077, 1077S4, 1077S6, 1077S8, 1077S10, 125154 and 125 1 S25-outlet connection is 1" FPT. All others are %" FPT.

UTILITIES Electrical-Model 1077 - 115 or 230 volt (select one), `50/60-cycle, 1400 watts maximum. Model 1251 - 115 or 230 volt (select one) 50/60 cycle, 1400 or 2400 watts depending on the bath operating temperature. These figures exclude power requirements of electrical trans- mitters, some of which require their own power supplies. Connections are for `/z" conduit. Air-A 20 prig clean instrument air supply is required on those transmitters providing pneumatic output signal. Connections are `A" FPT. Cooling Water-Requirements depend on operating conditions. Connections are I/," FPT. Pressure regulation desirable. I/> gallon per minute maximum. DIMENSIONS Model 1077-[Approximate) 18" wide x 32" long x 57" high (Height depends on transmitter) Model 1251-[Approximate) 18" wide x 45" long x 56" high (Height depends on transmitter) WEIGHT Model 1077-N& weight opprox. 365 Ibs. Shipping weight ap- prox. 450 Ibs. Model 1251-Net might approx. 450 Ibs. Shipping weight ap- prox. 550 Ibs.

STANDARD EQUIPMENT Viscometer complete with transmitter as specified by the model number. Filter for external mounting. One capillary tube. One special etched stem viscosity thermometer.

BATH MEDIUM Bath medium is not included as standard equipment, but can be supplied at extra charge. Recommended fluid is a medicinal type oil with low viscosity fbelow 25 csk at 100°F.) and a flash point above the maximum op- erating temperature, or cI similar low viscosity silicone oil. Exploded view capillary and thermometer holder 9 for pressure trans- mitter instruments, showing capillary, capillary filter screen and themometer.