Feedwater Rw f 40

RWF40 Compact Universal Controller Flowrite SKB/C/D Valve Actuator Flowrite VF 599 Series Two-Way Valves Differential Pressure Transmitter with Three-Valve Manifold RWF40 Modulating Feedwater Control Valve

Application Guide

DPFC Quick Start Guide -06 Page 1 Section 1

Section 1 Overview Introduction 1-1 The Siemens Differential Pressure Feedwater Control (DPFC) is an integrated system based on a highly accurate Differential Pressure (DP) transducer(s) coupled to a RWF40 universal controller. The RWF40 controls the Feedwater valve actuator directly (electro-hydraulic actuator), or through an I to P converter (Pneumatic valve actuator). Many different actuators and feedwater valves are offered to accommodate different feedwater pressures and flows. The DPFC may be used on Firetube and Watertube Boilers, as well as Deareators. It can be set up as a single or a dual element level control, depending upon which sensors are connected. ModBus communications are also available via the RWF40, allowing the DPFC to interface with a building management system or a HMI (touch screen). These features make the DPFC extremely flexible, and ideally suited for use on most steam boilers and Deareators.

Figure 1-1.1 Typical Single Element DPFC

DPFC Quick Start Guide 6-14-06 Page 2 Section 1

Product Offering 1-2 RWF40 Universal Controller Options (All are 120VAC) RWF40.001A97 Configurable analog output

2 Configurable analog inputs Analog inputs forward or reverse scalable Accuracy to 0.1 WC Used for one or two element level control Configurable High and Low alarm points

RWF40.002B97 Same features as above, plus: RS-485 interface for ModBus communications.

Differential Pressure Transducer Options 7MF4433-NODISP Industrial Grade DP Transducer Used for : Level Sensing (linear) Flow Sensing (linear or square rt.)

Spanned 0 to 60 WC 2300 PSIG Max Operating Press. Accuracy of 0.1% of span (0.06 WC) Pushbutton, Laptop or HART configuration HART Communications IP65 (exceeds NEMA 4) Explosion proof, if properly installed Includes mounting hardware

7MF4433-DISP Same features as above plus: Viewable, multi-mode local display.

7MF4433-DISPR2 Same features as 7MF4433-DISP except:

Spanned 0 to 100 WC Accuracy of 0.1% of span (0.1 WC)

Differential Pressure Transducer Accessories

7MF94115BA 3-Valve Manifold for DP Transducer Billet Stainless Steel NPT threaded connections Includes mounting hardware, gaskets


Differential Pressure Sensor Accessories (continued)

15965-659 Flanges for DP Transducer Billet Stainless Steel NPT threaded connections Includes mounting hardware, gaskets Electro-Hydraulic Feedwater Valve Actuators

SKD62UA Valve actuator for use with VF599 Valves Maximum Stroke Adjustable Stroke Direct or reverse acting Adjustable opening characteristic Opening Time : 30 sec Closing Time : 15 sec Spring return closing 225 lb Positioning Force Analog Input, 4 to 20mA or 0 to 10 VDC 1000 Ohm signal can also be used NPSM for conduit connectors

SKC62UA Valve actuator for use with VF599 Valves Same as SKD62UA, except : 1 Maximum Stroke Opening Time : 120 sec Closing Time : 20 sec 630 lb Positioning Force

SKB62UA Valve actuator for use with VF599 Valves Same as SKD62UA, except : Opening Time : 120 sec Closing Time : 15 sec 630 lb Positioning Force


Electro-Hydraulic Feedwater Valve Actuator accessories

599-10048 Stem Reatainer Kit for use on valves up to 3 with

SKB/C actuators (10mm)

599-10049 Stem Reatainer Kit for use on valves, 4 to 6 with SKB/C actuators (14mm)

599-10071 Weathershield for the SKD62UA Actuator Makes the actuator NEMA 3R compliant when mounted vertically.

599-10065 Weathershield for the SKC/B 62UA Actuators Makes the actuator NEMA 3R compliant when mounted vertically.

ASC1.6 0% stoke auxiliary switch SPDT contacts Rating: 24V, 4A resistive, 2A inductive Feedwater Valves for use with Electro-Hydraulic Actuators 599-03xxx to 2 Brass Feedwater Valves Stainless Steel Caged Trim Max. Leak-by : 0.01% of rated Cv 100 to 1 Rangeability Complete listing in specifications, Section 6 599-06xxx 2 to 6 Cass Iron Feedwater Valves Stainless Steel Caged Trim Max. Leak-by : 0.01% of rated Cv 100 to 1 Rangeability

Complete listing in specifications, Section 6

Pneumatic Actuator, Feedwater Valve assemblies with positioning relay


283-03xxx Max inlet pressure to positioning relay : 60 PSIG Max positioning relay outlet pressure : 30 PSIG Max inlet pressure to Pneumatic Actuator :35 PSIG 1/8 NPT connections to positioning relay

Maximum Stroke Adjustable spring preload

Complete listing in specifications, Section 6 Penumatic Actuator, Feedwater Valve Actuator assembly accesories 545-208 Analog to Pneumatic Transducer

(4-20mA or 0-10VDC) to 3-15 PSIG 201-1000 Pressure Reducing Valve

142-279 2 Pressure Guage

0 -100 PSIG 908-051 Compressed Air Filter


Typical DPFC systems 1-3 Typical Single Element DPFC A typical single element DPFC system will include the following components: RWF40.001A97 Universal Controller 7MF4433-DISP Differential Pressure Transducer (for level) 7MF94115BA Three Valve Manifold for DP Transducer SK(D,C,B)62UA Electro-Hydraulic Feedwater Valve Actuator 599-10048 Stem Retainer Kit Used to couple SKB/C actuators to 599-0x Feedwater

valves up to 3 (10mm) 599-10049 Stem Retainer Kit Used to couple SKB/C actuators to 599-0x Feedwater

valves from 4 to 6 (14mm) 599-03xxx Feedwater Valve Installer Condensate Pot Assembly (see sketch in section 2-2) Supplied 24 VAC transformer, 30 VA (20 W) to power actuator Tubing and Tube Fittings Conduit, Wire, Piping Typical Two Element DPFC A typical two element DPFC system will include the previously mentioned items plus the following additional components: 7MF4433-DISP Differential Pressure Transducer (for flow) 7MF94115BA Three Valve Manifold for DP Transducer Installer 24 VAC transformer for second 4-20mA loop Supplied Important Safety Notes 1 - 4 All activities (mounting, installation, service work. etc.) must be performed by qualified staff. Ensure that all piping, tubing and pressure vessels (condensate pot) are in accordance with local and national codes. Before performing any work in the connection area of the RWF40, disconnect the unit from the main supply (all-polar disconnection).


Protection against electrical shock hazard on all connected electrical components must be ensured through good wiring and grounding practices. The system must be cool and depressurized before any work is performed on the water / steam side of the control. Failure to do this could result in severe injury or death. Condensation and the entry of water into the electronics compartment of any component must be avoided. Approvals 1- 5

Table 1- 5.1 Standards and certificates


Section 2 Mounting RWF40 Mounting 2-1 The RWF40 should be mounted inside an enclosure that will protect the RWF40 from dirt and moisture. The unit is mounted through the face of an enclosure, and uses a lead screw on each side of the casing to clamp the RWF40 to the panel face. It should be noted that the enclosure cutout must be accurate, or the RWF40 will not mount correctly. Figure 2-1.1 Illustrates the proper size cutout for the RWF40, and the overall dimensions of the RWF 40. After the cutout has been made, RWF40 can be inserted through the cutout back first. The lead screws can be clipped in either the top and bottom or the left and right sides. Figure 2-1.2 illustrates the lead screws clipped in the left and right sides. After this is done, tighten the lead screws, clamping the RWF40 to the face of the enclosure. Figure 2-1.2 illustrates this procedure, as well as RWF40 module removal. Please see Section 6 for specifications.

Figure 2-1.1 RWF40 Enclosure Cutout and Overall Dimensions (Inches)


Figure 2-1.2 RWF40 Enclosure Mounting, Module Removal

Differential Pressure Transducer Mounting 2-2 The Differential Pressure Transducer (DPT) can be used for two different types of sensing duty. In a typical single element DPFC, the DPT functions as a level sensing device that can accurately detect the difference in the level of two water columns. In a dual element DPFC, two DPT are used, one to sense level and the other to sense differential pressure across a flow element (orifice). This flow element is typically piped into the vessel outlet. The DPT is supplied with hardware and brackets that permit many different mounting orientations. The DPT is typically oriented right side up (transducer head above process connections, process connections horizontal) but it may also be oriented so that the process connections are vertical with the transducer head to the side. The DPT must not be oriented upside down (transducer head below process connections). Acceptable orientations are shown in Figure 2-2.1. After the DPT has been mounted in one of the permissible mounting orientations, accessories such as the 3-valve manifold or the flange kit may be mounted to the DPT. All necessary hardware and gaskets are provided with the 3-valve manifold and the flange kit.


Figure 2-2.1 DPT Overall Dimensions (mm and inches)

Figure 2-2.2 Acceptable DPT Orientations

When mounting and tubing the DPT for level sensing, a few important points must be observed. These points are as follows: 1. The DPT must be mounted on cold legs (drip legs) so that the water that the DPT is

exposed to is less than 200 o F.


2. The DPT must be mounted lower than the lowest measured level. This could be the bottom of the vessel (possibly in a deareator), or this could be halfway up the side of a vessel (as is done on a typical firetube boiler). The DPT can be mounted at any practical distance below the vessel.

3. The reference leg (-) of the DPT must remain full and at a constant level during operation. This is assured by using a Condensate Pot which is less than saturation temperature. The reference leg and the Condensate Pot must be filled with clean water during the initial Start-up. When used on steaming vessels (boilers and deaerators) the Condensate Pot will remain completely full due to the steam condensing in the below saturation temperature Condensate Pot.

4. The colder and larger the Condensate Pot, the better. For example, if the vessel is at saturation at 100 PSIG steam pressure, the water in the vessel is about 338 oF. If the Condensate Pot is distanced from the vessel (on a un-insulated pipe) the water in the Condensate Pot will be less than 338 oF, and will have a much lower likelihood to flashing in the event of rapid de-pressurization of the vessel. If the Condensate Pot is distanced enough to be less than 212 oF, Condensate Pot flashing will never take place. Achieving a temperature of 212 oF at the condensate pot is not always practical, so the effects of a rapid de-pressurization event severe enough to cause Condensate Pot flashing can be minimized by using a larger diameter, larger volume condensate pot.

5. Provisions should be made so that the DPT can be bled of air during start-up. This is typically done by loosening the plugs on the DPT opposite the process connection when the vessel is cold and under little or no pressure.

Figure 2-2.2 illustrates the preferred method of mounting a DPT and Condensate Pot to a typical deaerator vessel. Figure 2-2.3 illustrates another acceptable method that can be used to mount a DPT to a typical deaerator vessel. Figure 2-2.4 and 2-2.5 illustrate the preferred and acceptable methods (respectively) for mounting a DPT and Condensate Pot to a typical firetube boiler.

Figure 2-2.3 Preferred Mounting (Deaerator Vessel)


Figure 2-2.4 Acceptable Mounting (Deaerator Vessel)

Figure 2-2.5 Preferred Mounting (Firetube Boiler)


Figure 2-2.6 Acceptable Mounting (Firetube Boiler)

The difference between the preferred and the acceptable methods of mounting is the water column. The water column with blowndown valve is preferred since it provides a container for solids precipitation / separation, and also a means to flush these solids. This serves to keep the working leg of the transducer more debris free. The water column also serves to dampen turbulence that may be occurring in the vessel. Last but not least, the water column serves as an additional thermal barrier for the Condensate Pot. Typically, water columns are constructed from pressure rated 1 pipe. The Condensate Pot is the most important part of the reference leg, and necessary for almost all installations. This piece serves as a condensate reservoir that will not vary in level any great degree even if condensate flashing (due to depressurization) takes place. As was previously mentioned, the larger the Condensate Pot, the better. Specifically, it is best to make the Condensate Pot internal diameter as large as practical, while maintaining a 6 to 10 inch overall height. Figure 2-2.6 illustrates typical Condensate Pots.


Figure 2-2.7 Typical Condensate Pots (dimensions in inches)

Connection of the Condensate Pot to the DPT is usually accomplished with 3/8 Stainless Steel tubing, but other tubing / pipe of different material and / or larger diameter will also perform adequately.

If a second DPT is used to measure the DP across an orifice (as would be done in a two element DPFC) the second DPT should be mounted and tubing installed according to Figure 2-2.8. The DPT is installed below the steam flow orifice for thermal isolation. The two pieces of tubing going to the DPT (or legs) will fill up with water as the steam is cooled and condensed in the metal tubing. Care should be taken to ensure the water legs going to the DPT are installed so that the accumulated water in each leg is equal in height.

Figure 2-2.8 DPT Mounting for Steam Flow Orifice


Feedwater Valve / Electro-Hydraulic Valve Actuator Mounting 2-3

The 599-03 series of feedwater valve features female NPT threads on both the inlet and outlet of the valve. The valve body is brass, and features a stainless steel trim. The valve is typically mounted by the inlet and outlet piping. The 599-06 series of feedwater valve features a flanged connection on both the inlet and outlet of the valve. The valve body is cast iron, and also features a stainless steel trim. This valve is also typically mounted by the inlet and outlet piping. The electro-hydraulic actuators (SKB/C/D) are typically field mounted to an appropriately sized application-specific feedwater valve. The 599-0x feedwater valves require different actuator strokes and force depending upon their size and application. 599-0x valves from to 3 require an actuator having of stroke, and above 3 require an actuator having a 1 stroke. The force that is required is dependent upon the inlet pressure into the valve, and also if the valve is a normally open or normally closed valve. Specific information concerning valve / actuator sizing is included in Section 6. For normally closed valves (typically used in feedwater applications) full downward travel of the valve stem is full open. Full upward travel is full closed. For normally open valves, full downward travel of the valve stem is full closed. Full upward travel is full open. A complete listing of all valves with technical information is included in Section 6. Field mounting of the electro-hydraulic actuators to the 599-0x series feedwater valves is a relatively simple process. However, the SKD actuator mounts to feedwater valves differently than the SKB and SKC actuators. Figure 2-3.1 details the overall dimensions of the the SKD and the SKB/C actuators. Figure 2-3.2 and 2-3.3 detail the SKD and SKB/C mounting procedures respectively. Both the SKD and the SKB/C can be mounted with the valve below the actuator (vertically, knob up) and also with the valve beside the actuator (horizontally). The valve actuator must not be mounted with the valve above the actuator (vertically, knob down).

Figure 2-3.1 SKB/C and SKD Overall Dimensions (inches and mm)


Figure 2-3.2 Mounting SKD Actuator to 599-0x Feedwater valves

Place the Actuator in manual mode by rotating the knob on the very top of the actuator clockwise until the manual flag appears. This will also move the valve stem retainer downwards. Loosen the socket head screws on both the valve stem retainer and the actuator yoke.

Slide the actuator down over the valve stem and the valve bonnet. Rotate the actuator to the desired position about the valve stem. Ensure that the raised area on the I.D. of the valve stem retainer is aligned into the machined groove in the valve stem. Hold the valve stem retainer, tighten the socket head screws. Ensure that the raised area on the ID of the valve stem retainer stays in the valve stem groove during the tightening process. Tighten the socket head screws on the actuator yoke with a torque not exceeding 40 in-lb.

Place the actuator back in auto by rotating the knob on the very top of the actuator counterclockwise until the MAN flag retracts.


Figure 2-3.3 Mounting SKB/C Actuator to 599-0x Feedwater valves Remove the valve stem retainer and the valve stem retainer nut from the packaging.

Slide the narrow end of the nut over the valve stem.

The 10mm valve stem retainer is for use with valves up to 3. The 14mm valve stem retainer is for use with valves from 4 to 6.

Spread the valve stem retainer just enough to fit it into the valve stem groove. Be very careful not to break the valve stem retainer in half.

Gently close the valve stem retainer by hand. When the nut is slid up the valve stem, the valve stem retainer should fit inside the nut.


Figure 2-3.3 Mounting SKB/C Actuator to 599-0x Feedwater valves Loosen the two actuator retainer bolts, and remove the actuator retainer. The actuator retainer bolts have a 3/8 head. Next, slide the valve actuator onto the feedwater valve. Unlike the SKD, the SKC/B series of actuator slides onto the valve bonnet from the side. Replace the actuator retainer and the actuator retainer retaining bolts. Install the bolts finger tight. At this time, the valve actuator can be turned about the valve stem to the desired position. After the valve is in the desired position, tighten the actuator retainer retaining bolts with a torque not exceeding 40 in-lb.

Unfold the crank arm on top of the actuator. Turn the crank clockwise. This will lower the threaded nipple that the valve stem retainer nut threads onto. When in the correct position, the window will show a 16 for a SKB and a 32 for a SKC.

Slide the valve stem retainer nut up the valve stem. Take care to ensure the valve stem retainer fits inside the nut and that the retainer stays fully engaged with the valve stem groove. Thread the valve stem retainer nut onto the threaded nipple. Tighten the valve stem retainer nut. This requires a 24 mm open end wrench. Turn the crank counterclockwise until numbers no longer show in the window (About 8 rev. for SKB, and about 16 rev. for SKC) Fold the crank arm on top of the actuator.


If positive 0% stroke indication is desired, a limit switch can be added to the SKB/C/D. This switch is an ASC1.6, and it features a SPDT design. This switch is mounted under the cover of the SKB/C/D with small machine screws. The switch can be moved up and down slightly before fully tightening the machine screws so that the activation point can be fine tuned.

Figure 2-3.4 Mounting ASC 1.6 switch to SKB\C and SKD

599 Series Feedwater Valve / Pneumatic Valve Actuator Mounting 2-4 Pneumatic feedwater valve actuators are typically factory mounted to an appropriately sized application-specific feedwater valve so field assembly of the valve / actuator is not necessary. The pneumatic feedwater valve actuator assembly also typically includes a positioning relay for highly accurate control. Figure 2-4.2 shows a pneumatic valve actuator with a positioning relay. The valve actuator can be mounted in any orientation, except upside down (with the actuator diaphragm pointing to the floor) The pneumatic feedwater valve actuator assembly may need adjustment in the field. Figure 2-4.1 details this adjustment procedure.


Figure 2-4.1 Overall Dimensions (in inches) and Adjustment of 8 Pneumatic Feedwater Valve Actuator (without positioning relay)

Normally closed feedwater valves: To Increase the start to open pressure turn the adjustment screw from the right to the left To decrease the start to open pressure, turn the adjustment screw from the left to the right. Normally open feedwater valves: To Increase the start to close pressure turn the adjustment screw from the right to the left To decrease the start to close pressure, turn the adjustment screw from the left to the right.

As the pressure differential across the feedwater valve increases, the span of the Actuator spring will decrease.

Figure 2-4.2 Pneumatic Feedwater Valve Actuator (with positioning relay)


The Pneumatic Feedwater Valve Actuator, when combined with the positioning relay offers much improved control compared to the Pneumatic Feedwater Valve alone. The reason for this is that the positioning relay is designed to achieve a given actuator position (actuator stroke) for a given pneumatic signal. The positioning relay varies the air pressure to the diaphragm in the feedwater valve actuator to achieve a certain actuator position which is monitored by the feedback arm. The air pressure delivered to the actuator diaphragm can be greater or less than the original pneumatic signal. The end result of the positioning relay is that the actuator and therefore feewater valve position are largely unaffected by the differential pressure across the feedwater valve. If the positioning relay is not used, the differential pressure across the feedwater valve will influence the actuator position, since the differential pressure causes pushing or pulling forces on the valve stem. With these variable pushing or pulling forces present on the actuator stem, a certain pneumatic signal will not always position the feedwater valve in the same place. For this reason, the use of the positioning relay is recommended on deaerators (small to medium variance in DP across the feedwater valve) and is highly recommended on boilers (medium to large variance in DP across the feedwater valve). The Pneumatic Valve Actuator, Feedwater valve, and Positioning relay are assembled and the positioning relay calibrated prior to shipment. The positioning relay generally does not need to be recalibrated in the field. However, if recalibration or replacement is necessary, calibration instructions for the positioning relay can be found in a document entitled RL147 Positioning Relay (Document Number 155-038P25).

Pneumatic Valve Actuator Mounting Accessories 2-5

A number of accessories are available to complete the installation of the pneumatic valve actuator. These accessories include: Electric to Pneumatic Transducers, Pressure Regulators, Compressed Air Filters, and Pressure Gauges. In order to use a Pneumatic Valve Actuator with a RWF40, an Electric to Pneumatic Transducer (AO-P) is necessary. The device takes a 4-20mA or a 0 to 10 Volt DC signal and converts this electrical signal to a pneumatic (air pressure) signal. The electric input signal can be selected via a jumper on the back of the AO-P. This jumper is shown in Figure 2-5.1. The AO-P also features an auto / hand switch. This enables the pressure output of the AO-P to be manually adjusted with a screwdriver when the AO-P is in hand mode. The AO-P is available in both a panel mount and a remote mount. The dimensions of these two different models are shown in Figure 2-5.2

Figure 2-5.1 Jumper Settings, Output of the Electric to Pneumatic Transducer (AO-P)


Figure 2-5.2 AO-P Overall Dimensions (in inches and mm)

Documents

Feedwater Rw f 40