Adca Training This presentation is only a guideline, that can only be completed by a trained personel. Part 5 Adca Steam Equipment E 10.08

Part 5 Control Valves Components of Control Valves Humidification

 Modern plants demand accurate distribution and control of fluids, either they are liquid or gas.  Among several elements required for an effective control system – instruments, probes, controllers, etc- control valves play a very important role.  In spite of their relevance as control element in an automatic control loop, control valves are mostly “misunderstood” and even disregarded.  Thus, control valves correct selection and sizing is capital to the perfect behaviour of control loop.

Measuring Element Feedback signal Corrective signal Controller Temperature Pressure Level Density Humidity … Fluid  The signal transmited to the controller is compared with the desired set point and if necessary will re-adjust the control valve through a corrective signal. Positioner Valve Body Actuator

Self Regulating Valves Automatic Control Valves (Globe Type) Self Acting Temperature Control Valves Three Way Two Way Plug (Single Seat) Two Way Cage (Single Seat) Balanced Mixing Diverting Unbalanced

Adcatrol TR 25  The expansion of the temperature sensitive fluid in the sensor is transmitted through capillary tubing to the valve actuator. Here it is turned into linear thrust to actuate the valve. When the temperature falls, the fluid contracts and a return spring moves the valve in the opposite direction.  The sensor incorporates an overload bellows to take up any excess pressure which may develop by any temperature over-run.  Temperature over-run can therefore be tolerated within certain limits without rupture of the system. Direct action Heating Reverse action Cooling

Adcatrol Actuator Electric Pneumatic Adcatrol Valve Body Two Way V25 Three Way V253 Adcatrol EV25 EV253 Adcatrol PV25 PV253 EL Series PA Series

PV 25I PV 25G PWV40I PV 253G EV 16G

PAV 20 PPV 16 PPV 25I

PV 25S  The electro-pneumatic positioner requires an input signal of 4÷20 mA for proportional control actuator. The positioner compares the output signal from a controller with the position feedback, and varies a pneumatic output signal to the actuator accordingly. The actuator position is therefore guaranteed for any controller output signal and the effects of varying differential pressure.  The pneumatic positioner requires an input signal of 0,2÷1bar (3÷15psi) for proportional control actuator. The positioner compares the output signal from a controller with the position feedback, and varies a pneumatic output signal to the actuator accordingly. The actuator position is therefore guaranteed for any controller output signal and the effects of varying differential pressure. PP 981 PE 986

Two-way valve arrangement Fluid : saturated steam Three – way mixing valve arrangement (mixing regulation) Fluids: water, diathermic oil, … Three – way mixing valve arrangement(diverting regulation) Fluids: water, diathermic oil, … Three – way diverting valve arrangement Fluids: water, diathermic oil, … Two-way valve arrangement Fluids: water, diathermic oil,…

PT – On-off, the flow rate changes from 0 to 100% - fully open or fully closed control. PL – Linear, the flow capacity or Kv increases linearly with valve travel. The flow is directely proportional to the valve travel.Recommended when there are no relevant variations in differential pressure or flow rates EQP – Equal-percentage, for equal increments of valve plug travel the change in flow rate with respect to travel may be expressed as a constant percent of the flow rate at the time of the change. At constant differential pressure, the valve travel increase of 10% usually corresponds to a flow rate increase equal to 50% of the valve flow preceding the variation. The change in flow rate observed with respect to travel will be relatively small when the valve plug is near it’s seat and relatively high when the valve plug is nearly wide open. Recommended when there are wide variations in flow rate or differential pressure.  The choice of characteristic will depend upon the response required from the control system.

PARABOLIC PLUG (two-way valve) Characteristic: Flow direction: Ratio: Material: Sealing: Leakage: Application: linear or equal percentage from below 30:1 to 50:1 stainless steel metal to metal 0,005% of Kvs value steam, water and other fluids and gases without cavitation. PARABOLIC PLUG (two-way valve) Characteristic: Flow direction: Ratio: Material: Sealing: Leakage: Application: linear or equal percentage from below 30:1 to 50:1 stainless steel soft sealing-PTFE/Graphite rate 1, DIN 3230 Class V acc. DIN60534 steam, water and other fluids and gases up to 200ºC without cavitation. ON/OFF PLUG (two-way valve) Characteristic: Flow direction: Material: Sealing: Leakage: Application: none from below or above stainless steel metal to metal rate 3,DIN3230 shut off of all media ON/OFF PLUG (two-way valve) Characteristic: Flow direction: Material: Sealing: Leakage: Application: none from below or above stainless steel soft sealing-PTFE/Graphite rate 1,DIN3230 shut off of all media up to 200ºC

PERFORATED PLUG (two-way valve) Characteristic: Flow direction: Ratio: Material: Sealing: Leakage: Application: linear or equal percentage from above 30:1 to 40:1 stainless steel metal to metal 0,005% of Kvs value steam, water and other fluids and gases.Can be use where cavitation and flashing is present and if noise reduction is required. MICROFLOW PLUG (two-way valve) Characteristic: Flow direction: Ratio: Material: Sealing: Leakage: Application: linear or equal percentage from below 50:1 stainless steel metal to metal 0,005 of Kvs value steam, water and other fluids and gases where extremely low flow rates are present. MIXING PLUG (three-way valve) Characteristic: Ratio: Material: Sealing: Leakage: Application: linear/linear 30:1 to 50:1 stainless steel metal to metal 0,005% of Kvs value Water, diathermic oil, … DIVERTING PLUG (three-way valve) Characteristic: Ratio: Material: Sealing: Leakage: Application: linear /linear 30:1 stainless steel metal to metal 0,005 of Kvs value Water, diathermic oil,…

“V” RINGS WITH SPRING Type: Max.pressure : Max.temperature: Material: Application: V1.1 40bar 200ºC PTFE/Graphite Steam, water and other fluids “V” RINGS WITH SPRING Type: Max.pressure : Max.temperature: Material: Application: V2.1 40bar 180ºC PTFE Steam, water and other fluids GRAPHITE Type Max.pressure : Max.temperature: Material: Application: G1 40bar 400ºC Graphite Steam, water and other fluids “V” RINGS W/SPRING &COOLING FINS Type: Max.pressure : Max.temperature: Material: Application: V1.1 and VV1.1 40bar 250ºC PTFE/Graphite Steam, water and other fluids

BELLOWS Max.pressure : Max.temperature: Material: Application: 25bar 400ºC Stainless steel Water,diathermic oil,… “V” RINGS WITH SPRINGS Type: Max.pressure : Max.temperature: Material: Application: VV1.1 40bar 200ºC PTFE/Graphite Steam, water and other fluids

POWER SOURCE PneumaticElectricHydraulic IMPUT SIGNAL Low Electric Power PneumaticElectric FAILURE MODE ClosedOpenFail in Place (Or Combination, ie. electro-hydraulic)

Diaphragm Spring Loaded Piston Spring Loaded Reverse Action Air to Open Direct Action Air to Close Reverse Action Air to Open Direct Action Air to Close

QQuestions to ask What is passing through the valve Pressure and Temperature Flow rate 2 way or 3 way valve Preferably connections (flanged or threaded) Pneumatic or Electrically actuated Pneumatic: spring to open / spring to close Positioner:I/P 4-20mA or 0-10V P/P 0,2-1,0 bar (3-15psi) Body material preference Application (heat exchanger, jacket vessel, steam cooker, etc)

TThe valve sizing is based on the calculation of the Kv coefficient. TThe formulas, below indicated, allow the Kv calculation in accordance with the type of fluid and it’s operating condition.  A After the Kv calculation, the corresponding Kvs is available from the valve data sheet. If real operating data have been used for the calculation, as a rule the calculated Kv should be around 70% to 80% of the selected valve Kvs in order to guaranty proper regulation of maximum flow rate at the given operating conditions preventing that sometimes some precautionary additions will result in undesirable valve over sizing.  A At the same time it is necessary to check whether the minimum flow rate can be even regulated or not considering the chose valve rangeability. The Kv represents the quantity of water, expressed in cubic meters (m3) at 15ºC, that flows through the valve with a pressure drop of 1 bar, in one hour period.

Calculation of Kv value Pressure Drop Medium Liquids Saturated steam Gases a) b) KvFlow coefficientm3/h P1Upstream absolute pressurebar P2Downstream absolute pressurebar DpPressure drop (P1 – P2)bar Q1Flow ratem3/h Q2Flow rateKgs/h Q3Flow rateN.m3/h (0ºC – 1013 mbar) d1Specific weight of liquidKg/m3 d2Specific weight of gasKg/m3 TAbsolute temperature (T=273 + t ºC)ºK tFluid temperatureºC

EExample 1 Fluid: Saturated steam Application: temperature control Control signal: 4÷20mA Inlet pressure : P1= 6 bar g (7 bar a) Maximum permissible ΔP : 10% P2= 5,4bar g (6,4 bar a) Flow rate: 600Kg/h Since, the formula to apply is then we have: To the Kv value calculated from the operating data we add an allowance of at least 10% and thus obtain the minimum Kvs value which the valve to be selected should have. We can now select the valve from the datasheet. Valve selected V25G DN32 PN16. Now it is necessary to select the actuator : Electric or Pneumatic.

 Example 1 Since considered pressure drop through the valve is negligible we may consider the maximum operating pressure (6bar) for the actuator selection. Thus both the PA280 with signal 0,4÷1,2bar or 0,4÷2bar can be used. The valve should be fitted with the electric-pneumatic positioner PE 986 with an 4÷20mA input signal and pneumatic output for proportional actuator control. NOTE: 0,2÷1bar control signal actuator are recommended for pneumatic instrumentaion control signal only.

EExample 1 In this case the EL12 electric actuator will be enough for the application, also complete with 4÷20mA PEL Positioner. For a correct request, the desired voltage actuator should be referred.

 Example 2 Fluid: Saturated steam Application: Pressure reducing station Inlet pressure: P1= 10 bar g (11bar a) P2=1 bar g (2 bar a) Flow rate: Kg/h Since, the formula to apply is then we have: To the Kv value calculated from the operating data we add an allowance of at least 10% and thus obtain the minimum Kvs value which the valve to be selected should have. Since the pressure drop is too high it is expected some noise on the valve and some vibration on the trim, for overcame this problems, we should apply a perforated plug. The perforated plug do not have the nominal seat diameter so we should consult the table for perforated plug and select the nearest Kvs value.

 Example 2 From the table of selection for perforated plugs we can choose a valve DN125 with a 100mm seat diameter and a Kvs of 121m3/h, that will meet our requirements. The adequate actuator must now be selected.

 Typical Heat Exchanger Temperature Control

Pressure controller Pressure transmitter PV25 Control valve with electro pneumatic positioner

 Whether for industrial efficiency questions or simply for well-being reasons, air’s humidification is essential in different air conditioning processes, either heating or cooling.  Humidity quantities added into the air are determined by air’s application, its original features and by all transformation it will suffer on the treatment systems, such as temperature changes. That value is usually defined by HVAC designers.  For humidification and when there’s live steam available (hospitals and plants) it’s common the use of type DSH direct steam humidifiers.

Due to little flows sometimes involved, control valves used in these applications are mainly of reduced bore or even microflow in order to assure a fine control. Steam Pressure Reducing Valve PRV25 Adcatrol PV25I Steam injector Air duct Steam seperator S25 Microflow plug design