PA FAN

[Kim byoungil]

CONTENTS

1. General

2. Design and Function

2.1      General

2.2      Inlet box

2.3      Impeller casings

2.4      Impellers

2.5      Shaft and bearings

2.6      Intermediate section

2.7      Diffuser

2.8      Motor

2.9      Pitch control system

2.9.1      Design

2.9.2      Control mechanism

2.9.3      Positioning sensing

1. GENERAL

The axial-flow PFT(Propeller Fan with Two impellers) fan is used as a primary air(PA) fan for a boiler in a plant application. Main component parts of the fan are :

1. One inlet box

2. Two impellers, each fitted with a casing

3. One intermediate section

4. One diffuser

Direct-drive electric motor is connected to the fan shaft via a so-called “floating shaft”.

The infinitely adjustable impeller blades permit control of the air flow through the fan while the fan is in operation. In boiler applications the purpose of this electro-hydraulic pitch control system is to maintain a vacuum in or air-flow through the boiler.

A sensor registers the pressure (actual value) at the location selected and transmits a corresponding signal to a regulator. (Note the sensor and regulator is not in the scope of ABB SEFAN.) The regulator is set for the flow required (ordered value). If actual and ordered values do not coincide, a corrective signal is transmitted to the electronics in the control cabinet causing it to actuate the proportional valve. Thus the blade pitch is changed to make the actual value coincide with the ordered value.

Figure2 illustrates how the pitch control system is employed.

The hydraulic unit supplies oil at a constant pressure to the proportional valve. From the proportional valve the hydraulic oil is directed to a hydraulic cylinder which actuates the mechanical components of the pitch control system, thereby changing the angle of the impeller blades. This change causes the air flow through the fan to change.

When the fan is in operation the two shaft supporting bearings are lubricated by circulating oil also supplied by hydraulic unit. Sensors are fitted in the bearings to facilitate the monitoring and supervising of temperature and vibrations.

2. DESIGN AND FUNCTION

2.1  General

All static parts of the fan, e.g. inlet box, impeller casing, intermediate section and diffuser are of fabricated design and bolted together. The rotating parts are made from forgings, castings and fabricated details. The impeller blades are made of sand-cast aluminium whereas other parts are fabricated mainly in steel and spheroidal graphite cast iron.

Access doors are provided for the purpose of inspection and service of the fan. Lifting eyes and rollers are fitted to facilitate maintenance. The roller-device is used at withdrawal of the diffuser from the impeller casing for overhaul of the impeller.

The entire fan installation is insulated mineral wool to reduce noise and heat radiation from the fan.

2.2  Inlet box

As shown in figure4 the inlet box is designed to deliver an evenly distributed air flow over the entire impeller. This is accomplished by means of the aerodynamic shape of the inlet box and guide vanes fitted in the outlet. Providing support for the pilot thrust bearing the inlet box also transfers of shaft forces to the foundation.

2.3  Impeller casings

The two impeller casings are identical, see figure5. Bolted access door is provided to facilitate inspection and replacement of impeller blades.

Inside surface of the casing are machined in ordered to achieve an exact tip clearance of impeller blades

2.4  Impellers

Both impellers of the PFT fan are similar in design. Figure6 shows the construction and component parts of the impellers which can be said to consist of one fixed part and one moving part as follows :

·  One fixed part comprising

-     One hub, secured onto the shaft

-     One hub collar for attachment of the blade shafts

-     One fairing

-     One impeller disk, protecting the internal moving parts of the impeller

·  One moving part comprising

-     One axially adjustable control disk

-     Control arms, attached to the control disk. The other end of control arm is connected to the respective blade attachment by means of an eccentrically supported control stud.

-     Impeller blades with blade attachment and bearing

-     Control mechanism

As earlier mentioned the pitch of the impeller blades is infinitely adjustable while the fan is in operation. Axial motion of the control disk is transformed by the control arms and their studs into rotary motion of the blade mounts.

All blades of both impellers are adjusted simultaneously. This is accomplished by means of a control rod which fitted in the common fan shaft connects the hydraulic cylinder with the two control disks.

Since the impellers are installed in series with one another the pressure increase obtained will be the same for both impellers.

2.5  Shaft and bearings

The shaft onto which the two impellers are fitted is supported by one spherical roller bearings and one CARB-bearing in separate housing, see figure7. The bearing nearest to the motor, the pilot bearing, takes up both axial and radial forces while the other bearing, the non-locating bearing, which is a CARB-bearing, takes up radial forces only.

With the fan in operation bolt bearings are lubricated continuously through pipe fittings on the bearing housing. The forced lubrication is accomplished with the aid of the lubrication unit.

Vibration sensor is fitted on both bearings. The sensor is connected to a monitor located adjacent to the fan. The monitor has relay outputs for alarm/trip circuits set at two different levels.

The bearing temperatures are monitored by means of temperature sensors, type 2K

The fan shaft is connected to the motor shaft by means of a floating shaft and two all steel couplings.

2.6  Intermediate section

Figure8 shows the intermediate section which is the component part connecting the two impeller casings. The guide vanes in the intermediate section help to create an evenly distributed axial flow of gas prior to impeller2

Providing support for the non-locating bearing of the fan shaft the intermediate section also transfers shaft forces to the foundation.

Inspection doors on the casing and central part of the intermediate section provide access for lubrication of the blade mounts of impeller2 without the need for dismantling.

Cooling air from the auxiliary cooling system enters the intermediate section through one of the profiled guide vanes.

2.7  Diffuser

The purpose of the diffuser, figure9, is to obtain an even and undisturbed reduction of the gas velocity and transforming it back to static pressure. This is accomplished by the guide vanes and the gradually increasing diameter of the diffuser. The central part of the diffuser contains a rotating union connected to the hydraulic cylinder for the pitch control system and a linkage system which transfers the motion of the control mechanism to an electrical position sensor.

2.8  Motor

Supplied by ALSTOM

2.9  Pitch control system

2.9.1   Design

Figure10 is an overview of the pitch control system and its main component parts :

1.  Hydraulic unit (see also the description in part “Component description”)

2.     Hydraulic lines between the hydraulic unit and the control mechanism.

3.  Control mechanism.

4.  Position sensor with limit switches.

5.  Control cabinet containing the control equipment.

In addition to the above mentioned items, the system includes for position indication and alarm, and a sensor and a regulator for control signals from the boiler. Since this equipment is supplied by the customer no detailed description is part of this manual. (Please see actual manual)

2.9.2   Control mechanism

Figure11 shows the control mechanism its main component parts :

1.     One rotating union

2.     One cylinder housing

3.     One double-acting hydraulic cylinder with a common piston rod

4.     One connecting pipe

5.     One  control rod

6.     One piston rod attachment

7.     One control yoke

The positioning of the control mechanism is determined by changing the direction of the hydraulic oil, which reaches the piston rod by way of the rotating union. In the center of the piston rod there are two passages from which the oil is directed into the hydraulic cylinder via two parts on the piston rod.

One end of the piston rod is attached to the cylinder housing by means of a flange. The other end is screwed into the control rod fitted into which is the control yoke. Via the cylinder housing and the control yoke the axial motion of the piston rod is transferred to the control disks of impeller 2 and 1

2.9.3   Position sensing

The position sensor, shown in figure12, consists mainly of a linkage system and a control box.

The linkage system transfers the axial motion of the control mechanism to a capacitive position sensor in the control box. The box also contains two limit switches, which are actuated when the control mechanism reaches the respective end position.

Control cabinet

The control cabinet contains the electronic equipment of the pitch control system, the vibration monitor, etc. see also the chapter entitled “Electrical drawings”

INSTALLATION  INSTRUCTION

PA FAN PFT-150-090

CONTENTS

1.     PRECAUTIONS FOR STORAGE OF PF FANS

2.     GENERAL

2.1     FOUNDATION

2.2     PREPARATIONS

2.3     ASSEMBLY

2.3.1      Foundation plates, Intermediate section, Rotor assembly with impeller 1, Impeller 2 and Inlet box

2.3.2      Motor

2.3.3      Control mechanism

2.3.4      Diffuser

2.3.5      Motor coupling

2.3.6      Hydraulic system

2.3.7      Inlet support, Transition, Silencer and Inlet hood

2.3.8      Ancillary equipment

2.3.9      Final steps

2.4     PRE-COMMISSIONING

2.4.1      Oil flushing

2.4.2      Check of safety and control system

2.5     APPENDICES

2.5.1      Erection report

1.  PRECAUTIONS FOR STORAGE OF PF FANS

The following instructions for storage also apply for the installation and commissioning period

1.

a)     Keep all parts of the fan rotor in a dry room with a relative humidity below 65%

b)     Keep all rotor parts under roof in drip-proof casings. The casing must be contain bags with desiccants. The bags must be replaced according to instructions from the bag manufacturer.

2.    The main shaft must be rotated by hand a few revolutions once a month. If the bearing assembly is stored in a casing, the shaft must be accessible through an opening with a cover

2.     The hydraulic unit must be

a)     Stored according to item 1 above, or

b)     Kept under roof and well filled with oil.

4.    All oil pipes, weather separate or assembled inside the diffuser, must be plugged in both ends. This is also applicable to the hoses.

5.    The proportional valve shall be kept in its original package and stored under roof.

6.    The control cabinet shall be kept in its original package and stored under roof until installation. After installation the cabinet must be protected until the anti-condensation heater is connected. Always keep door closed when no work is carried out.

7.    Special care must also be attended to the positioner cabinet and the instruments. Store under roof.

8.    Fan casing and other static parts must be protected from rain and condensation. Place parts in positions to avoid rain water filling. All machined parts must have a protective coating of wax, e.g. Tecty1, Dinitrol e.t.c.

9.    For parts supplied in containers, we recommend to keep all parts inside the container until it is time for installation of the parts.

10.  When storing equipment outdoors always place the parts on crossbars to avoid parts to be in direct contact with the ground.

11.  Always keep parts stored outdoors free from dirt and sand as clean surfaces are more corrosion resistant.

12.  Handle equipment with care to avoid distortions and painting damage as much as it is possible. Avoid lifting direct by fork lifters – use slings and eye bolts.

2.  GENERAL

For the proper installation we recommend all customers to order an erection supervisor from ABB Ventilation Products AB for the entire installation period of for the critical parts of it.

The following drawings are required for proper installation of the fan :

(All documents are part of the O&M manual)

GA drawing, General assembly drawing, Hydraulic and lubrication system, Rotor assembly drawing, Impeller1 assembly drawing, Impeller2 assembly  drawing, Hydraulic cylinder, Holding brake assembly, Positioner mechanism, Positioner cabinet, Flow monitoring equipment, Vibration monitoring equipment, Temperature detector, Tool box, Inlet expansion joint, Outlet expansion joint, Inlet support, Silencer assembly, Inlet hood, Hydraulic unit pitch control, PI-diagram

All documents references below will be according to the list above.

The fan is erected directly on a concrete foundation. Dimension and details of the foundation will be found on the General Arrangement Drawing and under the headline “Foundation” below

When cutting pipes tubes always use special cutting tool to avoid iron fillings penetrating the tubes.

Never bend tube by means of heating – use tube bending tools suitable for the dimension of tube

Fit sealing plugs and caps during the progress of the pipe installation work to prevent contamination of the hydraulic and lubrication system during installation.

Please note that the precautions for storage of the fan parts must be observed during the entire installation and commissioning period.

Check and sign off according to the “Erection Report” see appendices fill in this report subsequently.

2.1  Foundation

At design and grouting of the foundation all requirements and information given of the Fan General Arrangement drawing must be followed with special attention to the following :

·  Foundation plan(see GA)

·   Required dimension of the foundation with regard to fan loading and and applicable local building code or specifications from the client or his building engineer.

·  Box outs for the foundation bolts must be formed.

·  Frequency calculation must be performed to avoid primary resonances.

    Please see information on GA.

·   Cast in flat bars for shimming. The slide rails for withdrawal of diffuser will be cast in at the grouting later. Especially note that cast in flat bars have to be connected to the reinforcement or to be provided with tie-down bars.

·   Plinths for control cabinet and hydraulic unit.

·   Make provisions for steps up to the foundation for the daily maintenance as required.

·   For the final grouting of the boxed out holes and up to final level expanding concrete of quality K50 or better to be used.

After grouting inspect and verify that the finished foundation is according to the foundation drawing and the GA drawing requirements. Make sure the upper side is plane within normal building tolerance (+/- 10mm), the boxed out holes are correctly located as well as the flat bars and the slide rails.

Also check dimensions with regard to references for elevation, lateral and longitudinal position in the building.

2.2  Preparations

Figure1 gives a general view of the fan identifying its main component parts. Please refer also to the General Arrangement and Fan Assembly Drawings for further information.

1.    Make sure inspection and approval of the foundation after grouting has been made and that it is verified.

2.    Check the datum positions for elevation and lateral and longitudinal positions. Together with clients representative set positions for the fan shaft centerline in elevation and lateral position and the inlet duct centerline position. For the measurements use theodolite and/or other suitable instruments.

3.    Make sure all necessary documents are available and are of the latest revision.

2.     Make sure all necessary tools and lifting equipment are available.

·     Crane for lifting(suitable for the actual required lifting capacity and service range). Fixed equipment as well as mobile crane may be suitable.

·     Lifting tools (slings, jacks, winches, hoists, hooks, eyes etc). Make sure they are approved and suitable for the capacity required.

·     Ordinary hand tools.

·     Special tools. Included in the delivery, see drawing V1618332

·     Tube bending and cutting tools for diameter 15 and 22mm.

·     Dynamometric wrench for the required torque.

·     Tools for measurement : level gauge, plummet line, gauge rod, sliding caliper etc.

·     For alignment of the coupling laser equipment of suitable indicator gauge.

3.     Clean up the concrete foundation and the surrounding area. Ensure that the boxed out holes for the foundation bolts are clean and free from water and foreign objects.

4.     Fit the coupling hub of the intermediate shaft onto the motor shaft and tighten the set screw against the shaft key.

5.     Fit the coupling hub of the intermediate shaft onto the fan shaft. Fit the stop disc and tighten the set screws against both shaft keys.

2.3  Assembly

2.3.1 Foundation plates, Intermediate section, Rotor assembly with impeller 1, Impeller 2 and Inlet box

     Place the foundation plates with rotor unit onto the concrete plinths(A). Also place 25mm shim plates between the foundation plates and the concrete plinths. Adjust the height of the gases(b) with shims until both top surfaces of the bases are at the same horizontal level.

2.     Fit the intermediate section onto the foundation plates.

3.     Fit the impeller 1, shaft bearings and sealings in the intermediate section.

4.     Fit impeller casing 1(incl. Seal) onto the intermediate section.

5.     Fit the inlet box onto the foundation plates.
N.B Before moving the inlet box all the way towards the impeller casing, fit the sealing cone(located on the fan shaft). Make sure that the inspection cover does not interfere with the lifting beams in the inlet box. Use seal at each joint.

6.     Verify that the top surface of the foundation plates are still at the same level and also that the center axis of the fan is at the specified height. If not, adjust the shims.

7.     Make a preliminary check of all rotor clearance. If necessary remove the tack welds of the inlet box flange to adjust.

8.     Loosen the lower nut of the anchor bolts about 10mm and tighten the upper nuts, first with a torque 140Nm and finally with 200Nm.

9.     Check the alignment and adjust as required.

10.   Complete the grouting of the foundation plates.

11.   Fit the bolts for the bearing housing in the inlet box.

12.   Fit the sealing cone to the flange of the intermediate section.

 N.B. Plastic sealing ring and gasket

13.   Fit the impelle2 complete with blades onto the end of the shaft. Fit the lifting eye onto the blade holder closet to the key-way in the impeller hub and lifting eye onto the impeller huh.

14.   Coat the shaft with Molycote BR2 or equal. Fit the key.

15.   Lift the impeller (control mechanism removed) into position for mounting onto the shaft. Lift the impeller in the lifting eye on the hub. Then raise the impeller into vertical position with the lifting eye on the blade holder.

16.   Mount the impeller onto the shaft using the mounting tools in the tool kit(see drawing V1613641). Secure the impeller with the shaft end plate.

17.   Fit the impeller casing2 onto the intermediate section. Do not forget the gasket.

18.   Verify that the clearance between the blade tips and the casing of both impellers are within the limits specified on the assembly drawing.

 N.B.  To simulate the centrifugal force while the tip clearance is being measured the blade subject to measurement shall be pressed outwards as far as the axial of the blade permits.

2.3.2 Motor

1.     Mount the four sole plates under the motor feet, including 2mm shims.

2.     Lift the motor/template to designed place and center the motor at the same  time to the center line of the fan. Verify that motor has been aligned axial direction, see assembly drawing.

3.     Complete the grouting of the sole plates when the alignment is satisfactory.

4.     Loose the motor/template and tighten the foundation bolts, which holding the sole plates. Torque : see the assembly drawing.

5.     Lift the motor/template to designed place and align the motor in vertical direction with help of jacking bolts. Shim between the sole plates and the motor foot as required.

6.     Align the motor in horizontal direction.

7.     Tighten the motor bolts. Torque : see the assembly drawing.

8.     Verify the alignment of the motor relative to the fan rotor

2.3.3 Control mechanism

1.    Mount the control rod at the piston rod of the cylinder

2.    Insert the cylinder(with the piston rod) in impeller2

3.    Mount the rotating coupling

4.    Insert the yoke in the oval groove of the control rod.

5.    Tighten the bolts holding the cylinder.
    Moment : see the impeller2 drawing

6.    Secure the yoke in the spacer of the impeller2
    Tighten the control yoke. Moment : see the assembly drawing.

2.3.4  Diffuser

1.     Install the diffuser onto shim plates(nominal thickness=25mm) adjustment may be necessary). Also fit the slide rail before grouting.

2.     Refer to the impeller assembly drawing and verify the axial play between diffuser and the impeller. If necessary loosen the diffuser flange to adjust the play before making the final welding.

3.     When the alignment satisfactory, assembly and tighten the foundation bolts against the diffuser foot plates.

4.     Use expanding concrete when making the grouting up to diffuser foot plates. Also make sure that the slide rails are seated against the lower side of the foot plates and under the rolls of the lifting device. Let the grout harden.

5.     When the concrete has hardened tighten the foundation bolts to 200Nm.

6.     Fit the sealing ring between the diffuser sealing cone and the impeller. Do not forget the gasket.

2.3.5 Motor coupling

Also see flap 2 for more information about the coupling.

1.   Re-check the alignment and adjust as required after the grouting has hardened.

2.   Fit the intermediate shaft according to the instruction for the coupling, see flap2. A lifting lug fitted in the central part of the inlet box is intended as a lifting attachment in conjunction with installation or removal of the floating shaft.

3.   Carry out a final alignment of the motor and fit the dowels. Permissible angular offset corresponds to 0.20mm axial run-out measured on the external diameter of the coupling flange.

4.   Refer to the Rotor assembly drawing and re-verify that all to tolerances between fan rotor and fan stator are within the tolerances specified.

5.   Fit the coupling guard.

2.3.6 Hydraulic system

1.  Locate and fix the hydraulic unit as shown on the General Arrangement Drawing. The hydraulic unit is delivered with a flushing plate instead of the proportional valve. The flushing plates is only used during the flushing procedure.

Note : For the piping installation it is important to :

a) Cut the tubes using a tube cutting device.

b) Lightly de-burr the inside and outside edge of the pipe ends.

c) Do not chamfer the pipe ends.

d) Check that the tubes are clean before erection.

2.   Install the hydraulic system as specified below and as shown on the Hydraulic System Drawing.

3.   Fit the hydraulic and lubrication systems components and lines acc. to Hydraulic System Drawing, excluding the hoses to the rotating union which will be fitted at a later stage.

4.   Make electrical connections acc. to the wiring diagrams supplied.

5.   Fill the hydraulic tank with flushing oil Shell Tellus S22 or equivalent

2.3.7 Inlet support, Transition, Silencer and inlet hood

1.     Erect the inlet support acc. to the Inlet Support Assembly drawing, and adjust the level on the connection plate on the support.

2.     Use expanding concrete and make the final grouting up to the lower side of the foot plate acc. to the Fan Outline Drawing. Let the grout harden. For hardening time please refer to the documentation for the grouting cement.

3.     When the concrete has hardened tighten the foundation bolts to 200Nm.

4.     Assembly the transition acc. to the Transition Assembly drawing and lift it in place on the inlet support.

5.     Assembly the silencer casing acc. to the Silencer Assembly drawing.

6.     Install the baffels in the silencer casing. Handle the baffels carefully.

7.     Lift the complete silencer in position and fit it on the transition.

8.     Erect the inlet hood with roof acc. to Inlet hood assembly. Lift the complete inlet hood in position and fit it on the silencer.

2.3.8 Ancillary equipment

1.     Refer to supplier documentation and fit the expansion joints at the fan inlet and outlet.

2.     Install the flow monitoring system according to drawing for the system.

3.     Fit the Vibration Detector and Temperature Detectors acc. to the corresponding drawing in the drawing list.

4.     Fit the positioner system according to the Positioner Mechanism and Positioner drawings and adjust it acc. to the Installation, Pitch Control System drawing.

5.     Locate the control cabinet and it to the plinth. See General Arrangement Drawing.

6.     Refer to the Electrical Drawings supplied and connect and support all cables between the fan and the cabinet. Note the vibration monitoring cable is a special cable included in the supply. All other cables are not supplied by ABB Ventilation Products AB.
Important ! Connect the control cabinet heater as soon as possible and keep on, always keep the cabinet door closet when no work inside is in progress.

2.3.9 Final steps

1.     Remove the stays in the inlet box inlet section.

2.     Clean the inside of the fan. Ensure that no tools or foreign objects are left inside the fan or in the ductwork upstream of the fan.

3.     Clean all damaged or corroded surface and make touch up painting according to painting procedure V5003312

4.     Fill in and sign off the Erection Report

2.4  Pre-commissioning

2.4.1 Oil flushing

1       Make a temporary by-pass for the rotating union inside the diffuser, by connecting one of its hoses to both connections on the hydraulic feed pipes for the rotating union. Divert the oil feed to the bearing housing directly to the outlet by loosening the feed pipes and the outlet hose from the bearing housing. Connect the feed pipe directly to the outlet hose by temporary plastic hoses (supplied with the Commissioning Consumables)

2       Start up the hydraulic unit (one pump only). Verify that the motor is running in the direction of the arrow on the motor and that the pump is giving pressure.

3       Flush the system in the way for 5hours. Ensure that no filters are by-passed(alarm) due to high oil viscosity (cold oil) or dirty oil.

4       Stop the hydraulic unit and turn the flush plates on the hydraulic unit 180°(changing the flush direction) and flush for 5hours further. The oil is now circulation in the opposite direction  between the hydraulic unit and the fan.

5       When the flushing is complete stop the hydraulic unit and reconnect the feed pipes and outlet hose to the bearing housing.

6       Disconnect the temporary by-pass hose for the rotating union.

7       If fitted earlier, remove the rotating union from the hydraulic cylinder. Secure the rotating union in a wire and fit the three hoses on to the rotating union as shown in figure4.

8       Fit the rotating union onto the control mechanism. Ensure that the gaskets in figure4 above are seated properly.

9       Connect the hoses to the hydraulic pressure(2pc) and return(1pc) pipes. Refer also to the Hydraulic System Drawing.

10    Change the hydraulic oil in the hydraulic unit to Shell Tellus S68 or equivalent. Change those filters that were in operation during the flushing. New ones are part of the commissioning spares.

11    Start up the second hydraulic oil pump. Verify that the motor is running in the direction of the arrow on the motor and that the pump is giving pressure.

12    Fit the proportional valve instead of the flushing plates on the hydraulic unit. Save the flushing plate in the tool box.

13    Sign off in the pre-commissioning check-list.

2.4.2 Check of safety and control system.

1.     Verify the operation of all interlocks and monitoring equipment. E.g : signals from switches are tested either by, where possible, activating the switch or by disconnecting cables from the switch. Vibration detector are checked by tapping the vibration pickup with e.g. a screwdriver handle. Thermal detectors are checked by remote reading of the ambient temperature.

2.     Adjust the control system.

3.     Sign off the pre-commissioning list.

2.5  Appendices

2.5.1 Erection report