ID FAN

[Kim byoungil]

CONTENTS

1.   General

2.   Design and Function

2.1      General

2.2      Inlet box

2.3      Impeller casing

2.4      Impeller

2.5      Shaft and bearing

2.6      Diffuser

2.7      Motor

2.8      Pitch control system

2.8.1      Design

2.8.2      Control mechanism

2.8.3      Positioning sensing

2.9      Cooling air system

1.  GENERAL

The axial-flow PFS(Propeller Fan with Single impeller) fan service as a forced draught(FD) fan for a boiler in a power plant application. Main component parts of the fan are :

1. One inlet box

2. One impeller, fitted with a casing

3. One diffuser

See figure1.

The main shaft is via a flexible coupling connected to a direct-drive electric motor (Supplied by ALSTOM).

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

Figure3 shows the FD-Fan and its main components parts.

All static parts of the fan, e.g. inlet box, impeller casing 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. The inlet box is supporting one end of the bearing assembly by a flange connection and transfers the shaft forces to the foundation.

Access doors facilitates inspection and service of the box and entrance to the central part for lubrication of the impeller bearings and inspection of the bearing assembly.

A lifting eye fitted in the central part of the inlet box is intended as a lifting attachment in conjunction with installation or removal of the bearing assembly.

2.3  Impeller casing

The impeller is enclosed in a protective casing, see figure5. A bolted access door is provided to facilitate replacement of impeller blades.

Inside surface of the casing are machined in ordered to achieve a minimum of impeller blade tip clearance.

2.4  Impeller

Figure6 shows the design and component parts of the impeller which basically consists of a fixed and moving part as follows :

·  The fixed part comprising

-     Hub, secured onto the shaft by means of a keyed shaft and an end washer.

-     Hub rim for attachment of the blade shafts.

-     Impeller fairing section.

-     Impeller disc, for covering and protecting the internal moving parts of the impeller.

·  The moving part comprising.

-     Axially adjustable control disk.

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

-     Blades with blade holder and bearing.

-     Control mechanism consisting of hydraulic cylinder and parts transferring the movement.

As earlier mentioned the pitch of the impeller blades is infinitely adjustable from the minimum to the maximum position 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 holders.

2.5  Shaft and bearings

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

Both bearings are lubricated by forced lubrication from a common lubrication and hydraulic system. (Hydraulic unit)

A single vibration sensor is fitted to the non-locating bearing for monitoring of the horizontal vibrations. The sensor is connected to a monitor located in the control cabinet. The monitor has relay outputs for alarm/trip circuits set at two different levels.

The bearing temperatures are monitored by means of temperature sensors.

The fan shaft is connected to the motor shaft via a flexible coupling.

2.6  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.

2.7 Motor

Supplied by ALSTOM

2.8  Pitch control system

2.8.1   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)

2.8.2   Control mechanism

Figure11 shows the control mechanism its main component parts :

1.     Rotating union

2.  Three control rods

3.  Double-acting hydraulic cylinder

4.  Piston rod flange

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 control disk by means of a flange and three control rods.

2.8.3   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”

2.9  Cooling air system

N.B. The cooling air system applies to gas temperatures above 80℃ only.

The auxiliary cooling air system consists of a fan and an associated piping system for distribution of the air to the diffuser of the fan. The system uses fresh air from the surrounding of the fan to cool mainly the pitch control mechanism and the bearings.

INSTALLATION  INSTRUCTION

ID FAN PFS-355-265

CONTENTS

1.      PRECAUTIONS FOR STORAGE OF PF FANS

2.      GENERAL

2.1   FOUNDATION

2.2   PREPARATIONS

2.3   ASSEMBLY

2.3.1      Inlet box, motor base and bearing assembly

2.3.2      Impeller

2.3.3      Motor, Impeller casing

2.3.4      Diffuser

2.3.5      Motor coupling alignment

2.3.6      Hydraulic system

2.3.7      Ancillary equipment

2.3.8      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

3.    The hydraulic unit must be

a)     Stored according to item1 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, Impeller 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, 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.

      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.

4.    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 V1617405.

·     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.

5.    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.

2.3  Assembly

2.3.1    Inlet box, motor base and bearing assembly

1.     Take in the following parts : Inlet box, motor base, bearing assembly, foundation bolts, shim plates, fan half coupling and the required assembly details.

2.     Please refer to fig2 and the GA drawing. Place the foundation bolts(5), with only the lower nut mounted, in their respective boxed out holes of the foundation according to the GA drawing.

3.     Please refer to fig2. Place the inlet box(1) and the motor base(4) on the 25mm plates on top of the cast-in flat bars(7), on the foundation. The following shim plate dimension are provided : 1,2,5,10 and 20mm by using the shim plates, align the inlet box to the ID Fan C/L level according to the GA drawing and earlier set out. With suitable shim plates, also make sure that the impeller end flange of the inlet box is vertical within ± 1mm. Make the final check on the connection flange for the bearing assembly. This flange must be as near vertical as it is possible to align it. It is also very important that the inlet box is laterally correctly positioned and aligned and that the inlet is in line with the centerlines for the inlet duct set out.

4.     Align the level of motor base(4) by adjusting the shim plates. Align the motor base axially to match the position of the bearing assembly feet and center it sideways. Make sure that the upper surfaces of the motor base are in level within ± 1mm.

5.     Fit the fan coupling half on the bearing assembly shaft end. Before fitting, thoroughly clean the surfaces of the shaft end and the coupling bore with white spirit or similar. Apply Molycote BR2 or equal grease on the surfaces before fitting. If it is not possible to fit the coupling half without heating, heat up coupling half carefully evenly and fit the coupling. Do not forget the key.

6.     Prepare the bearing assembly(3) for mounting, by installing the lubricating system fitting and tubing(2). Clean up the tubes with compressed air before they are connected and plug openings with plastic caps afterwards. For specific detail, refer to the Hydraulic System Drawing.

7.     Lift the bearing assembly(3) into the inlet box. 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 bearing assembly.

8.     Fit the bearing assembly(3) onto the flange provided in the inlet box and the pedestal on the motor base. Verify that the C/L of the shaft is concentric with the cylindrical part of the inlet box and is horizontal. If necessary re-adjust the shim thickness of the motor base. Also measure the axial position of the bearing assembly to verify that the clearance between impeller rim and inlet box meets the requirement specified on the Fan Assembly Drawing. Do not fit the position of the bearing assembly with the tapered pins at this stage. Further adjustment is necessary later.

9.     When the alignment as per item 8 is satisfactory, mount the upper nuts on the foundation bolts and tighten it against the foot plate(Torque 140Nm). The bolt threads shall protrude about 10mm over the upper nuts.

10.   Use expanding concrete(quality see headline foundation) and make the first grouting, for inlet box and motor base, up to the level(8) in figure2. No grouting on inside of the surrounding tube of the foundation bolts. Let the grouting harden. For hardening time please refer to the documentation for the grouting cement.

11.   When the grouting has hardened, screw the lower nuts down about 10mm on the foundation bolts and tighten the upper nuts to pre-tension the foundation bolts. First torque 140Nm, and then to 200Nm. Finally re-check the alignment. Adjust as necessary.

12.   Complete the lubricating tube installation. Clean the tubes with compressed air before connection and plug open tubes afterwards.