DR4500A Truline HTST, STLR, and Pasteurization Flow ... - Honeywell

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44-45-03-16Page 4Model DR45AHRecorder/ControllerOn the DR45AH recorder, the divertvalve temperature is printed on thechart when Input 1 is programmed asa Digital Reference TemperatureIndicator.When a diversion occurs, the DR45AHrecorder/controller will automaticallyprint on the chart the temperaturemeasured at the divert valve by theDigital Reference Thermometer andthen, when forward flow is startedagain after the diversion, it will printthe temperature again.In addition, there are red and greenindicator lights on the front of therecorder that provide a visualindication of forward flow or flowdiversion.Milk Pasteurization ProcessFigure 3 is a flow diagram of the HTSTmilk pasteurization process. Milk flowsfrom the raw milk supply tank throughthe plate-type heat exchanger, whereit is heated to pasteurizationtemperature prior to entering theholding tube.The tube size ensures that the milkremains at the pasteurizationtemperature for the required time.Hot milk temperature is measured as itleaves the holding tube. If thistemperature is above the pasteurizationtemperature, the DR45AHHTST allows milk flow to proceed topackaging or storage. If the milk isbelow pasteurization temperature, theDR45AH HTST diverts it to the rawmilk tank for reprocessing.For this application, DR45AH HTSTuses two analog inputs, one digitalinput, one 3-mode controller and oneon-off controller to control:• hot water flow to the plate heatexchanger• Flow diversion valve position.Pasteurization temperature controlconsists of recording the informationshown on the circular chart (Figure 4)and implementing the followingstrategies:Model DR45AHRecorder/Controller, continuedMilk Pasteurization Process , cont.1. The first analog input is hot watertemperature (if Digital ReferenceTemperature option is selected,then Input 3 is the Hot WaterTemperature) , which indirectlycontrols milk temperature in theplate heat exchanger. Thistemperature may be recorded.2. The hot milk temperature is thesecond analog input. Thistemperature is recorded.The high-precision RTD sensorprovides this temperaturemeasurement. DR45AH HTSTuses 100-ohm ( α = 0.00385 )platinum bulb actuation to providehot milk temperaturemeasurement accuracy of ±0.3°F3. A switch on the flow diversionvalve provides the digital input toactivate the frequency pen thatrecords the valve position on theouter portion of the chart. The usersupplies and installs the two relaysthat connect therecorder/controller to thepasteurizer system wiring.You can also record the flow diversiontemperature setpoint without anadditional analog input.Model DR45ASSafety Thermal Limit RecorderThe DR45AS (STLR) model providesall the same features of the DR45AHHTST recorder without the integral hotwater control loop.The DR45AS model is set up to recordthe hot milk temperature as well as theflow diversion valve position and toindicate this position using red andgreen lights on the front of therecorder.Optionally, it can also be set up withthe integral Digital Reference feature.Model DR45APRecorder/ControllerThe DR45AP Pasteurization Flowrecorder/controller can be set up tocontrol the flow rate in a pasteurizationprocess.In addition to the normal divert valvecontrol provided by high and low flowlimit setpoints, optional inputs can beset up to display and record the Rawand Pasteurized pressures in thesystem.The recorder/controller will display, inthe lower display, the system high andlow pressures from independentpressure transmitters and control thesystem back pressure using thesecond control output from therecorder/controller.In addition, a high-pressure limitoutput can be set.Optional red and green lights areavailable on the front of the recorderthat provide a visual indication offorward flow or flow diversion.Milk Pasteurization ProcessThe DR45AP controls the flow rate ina pasteurization process (Figure 3).The flow is controlled from the flowinput from a pressure transmitter orMagnetic flowmeter in the constantflow line.The recorder uses PID control and a4-20mA output to control a variablespeed pump, which adjusts the flow inthe system.The differential pressure function usespressure inputs from Input 2 and Input3 to measure and display the high andlow system pressures (Input 2 – Input3) and uses this value and the optionalsecond 4-20 mA control output tocontrol the system back pressure.Diverts are based on High Flow orLow Flow setpoints configured in therecorder/controller. Diversion to theRaw milk tank occurs when the flowrate is below the Low Flow setpoint orabove the High flow setpoint.There is a Time Delay that can beconfigured to occur before forwardflow will begin. The configurable rangefor this time delay is from 0 to 60seconds.continued
44-45-03-16Page 5Model DR45APRecorder/Controller, continuedMilk Pasteurization Process,continuedFor Pasteurization Flow, DR45APuses one analog input for flow, onedigital input, one three modecontroller, and one On/Off controller tocontrol:• process flow rate• flow diversion valve positionIf controlling system back-pressure,two additional analog inputs and one3-mode, 4-20 mA controller with twoadditional relay outputs is required.Pasteurization flow control consists ofrecording the information shown onthe circular chart (Figure 5) for Input 1flow and implementing the followingstrategies:3. The first analog input is ProcessFlow.2. Optional Inputs 2, Input 3, andControl 2 output can be set torecord the system high and lowpressure for differential pressuremeasurement and to control thesystem back pressure.Truline Pasteruization (Flow)Recorder/Controller3. A switch on the flow diversionvalve provides the digital input toactivate the frequency pen thatrecords the valve position on theouter portion of the chart. Theuser supplies and installs the tworelays that connect therecorder/controller to thepasteurizer system wiring.Truline HTSTRecorder/ControllerFlow Recorder OptionSystem Back PressureControl OutputVacuumBreakerOptional HighFlowAlarm4–20mAOutput1Signal fromMagneticFlowmeterPasteurizedOutDivert LineHPLPFlow Recorder OptionBooster PressureDifferential SwitchRTDMilkTemp.FlowDiversionDeviceHoldingTubeSteamTemp.RTDRegeneratorFlow TransmitterHeaterSectionHot Wateror SteamFlow Control ValveRecycle LineBY-PassValveMagnetic Flowmeter1Signal toFlow RateRecorderRaw InBoosterPumpAC DriveCentrifugal Timing PumpConstant Level TankLEGENDPasteurized MilkRaw MilkHot Water/SteamSignalPressureFigure 3—Diagram of the Milk Pasteurization Process
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DR4500A Truline HTST, STLR, and Pasteurization Flow ... - Honeywell

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