1、THE ENGINEERING EQUIPMENT AND MATERIALS USERS ASSOCIATION Industrial Cooling Tower Fans and Fin Fans Guide for Design, Maintenance and Operation PUBLICATION 215 Edition 1 Released by IHS. Not for resale THE ENGINEERING EQUIPMENT AND MATERIALS USERS ASSOCIATION Industrial Cooling Tower Fans and Fin F
2、ans Guide for Design, Maintenance and Operation PUBLICATION 215 Edition 1 Copyright 2009 The Engineering Equipment and Materials Users Association. A company limited by guarantee. Registered in England. Company number 477838. ISBN 0 85931 163 2 Imprint reference 01-2009 Registered and Trading Addres
3、s 10-12 Lovat Lane London EC3R 8DN Telephone: +44 (0)20 7621 0011 Fax: +44 (0)20 7621 0022 E-mail: saleseemua.org Website: www.eemua.org EEMUA Publication 215 - Industrial Cooling Tower Fans and Fin Fans EEMUA ii ENGINEERING EQUIPMENT AND MATERIALS USERS ASSOCIATION The Engineering Equipment and Mat
4、erials Users Association, more commonly known as EEMUA, is a European non-profit membership Association helping companies that own or operate industrial facilities - the users of engineering equipment and materials. EEMUA aims to improve the safety, environmental and operating performance of industr
5、ial facilities in the most cost-effective way, thereby demonstrating and pursuing leadership in asset management. EEMUA Members pursue these aims through collaboration for mutual benefit, sharing engineering experiences and expertise and by promoting their distinct interests as the users of engineer
6、ing products. Specifically, the aims of EEMUA Member companies are achieved by: providing the organisation within which networking, information sharing and collaboration on non-competitive technical matters can take place; influencing the way written regulations are interpreted and applied in practi
7、ce; presenting and promoting Members views, and encouraging the application of good, sound engineering practices; developing user guides, specifications, training and competency schemes; facilitating Members participation in national and international standards making; influencing relevant national
8、and European legislation and regulations. Formed in 1949 as the Engineering Equipment Users Association, and re-named in 1983 (as a result of taking over the materials association, OCMA), EEMUA has for more than fifty years given companies that own and operate process plants, power stations and othe
9、r significant industrial facilities, a collaborative voice in addressing technical and engineering related issues that impact on good integrity management and asset management practices. The Association is open to companies of all sizes that meet its engineering user criteria. Further details of cur
10、rent Members of EEMUA is available on the Associations website, www.eemua.org. EEMUA activities often lead to the production of publications. These are prepared for Members use and are often offered for sale as well. A list of EEMUA publications for sale is given at the end of this Publication. The
11、full list is also on the Associations website, including details of on-line shopping facilities. To enquire about corporate Membership, write to enquirieseemua.org or call +44 (0)20 7621 0011. EEMUA Publication 215 - Industrial Cooling Tower Fans and Fin Fans EEMUA iii ABOUT THIS PUBLICATION Legal A
12、spects All rights, title and interest in this Publication shall belong to EEMUA. All rights are reserved. No part of this Publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means: electronic, mechanical, photocopying, recording or other, without the exp
13、ress prior written agreement of the EEMUA Executive Director. Infringement of copyright is illegal and also reduces the Associations income thereby jeopardising its ability to fund the production of future publications. It has been assumed in the preparation of this Publication that: the user will e
14、nsure selection of those parts of its contents appropriate to the intended application; and that such selection and application will be correctly carried out by appropriately qualified and competent persons for whose guidance this Publication has been prepared. EEMUA and the individual members of th
15、e Work Group that prepared this EEMUA Publication do not, and indeed cannot, make any representation or give any warranty or guarantee in connection with material contained herein. EEMUA and the individual members of the Work Group that prepared this EEMUA Publication expressly disclaim any liabilit
16、y or responsibility for damage or loss resulting from the use or reliance on this Publication. Any recommendations contained herein are based on the most authoritative information available at the time of writing and on current good engineering practice, but it is essential for the user to take acco
17、unt of pertinent subsequent developments and/or legislation. Any person who encounters an inaccuracy or ambiguity when making use of this Publication is asked to notify EEMUA without delay so that the matter may be investigated and appropriate action taken. Consultation and Feedback EEMUA encourages
18、 constructive comments on this Publication from both Members of the Association and others. Comments should be sent on the standard feedback form, a copy of which is provided towards the end of this Publication. An electronic version of the feedback form is available from EEMUA - e-mail your request
19、 for a copy to enquirieseemua.org, telephone your request to +44 (0)20 7621 0011, or download the form from the EEMUA website at www.eemua.org. Submit comments by e-mail (preferred) or post. Comments will be considered by the relevant EEMUA Technical Committee and may be incorporated in future editi
20、ons of this Publication. New editions will be publicised on the EEMUA website. Photographs courtesy of SABIC UK PetrochemicalsEEMUA Publication 215 - Industrial Cooling Tower Fans and Fin Fans EEMUA iv EEMUA Publication 215 - Industrial Cooling Tower Fans and Fin Fans EEMUA v Table of Contents 1. In
21、troduction .1 2. Scope .1 3. Guidance 3 3.1 Description of Mechanical Draught Cooling Towers 3 3.1.1 Motor and Drive Shaft 3 3.1.2 Central Gearbox 3 3.1.3 Fan Blade Materials 4 3.1.4 Guarding 4 3.1.5 Fan Condition Monitoring and Protection . 5 3.2 Description of Fin Fans 5 3.2.1 General Description
22、. 5 3.2.2 Fan Drive Belts 5 3.2.3 Fan Drive Shaft Mounting . 6 3.2.4 Fan Blades 6 3.2.5 Guarding 6 3.2.6 Fan Condition Monitoring and Protection . 6 3.3 Modes of Mechanical Failure . 6 3.3.1 Corrosion Related Failures 6 3.3.2 Water Ingress into GRP Blades 7 3.3.3 Fatigue Failure of Fan Blades . 7 3.
23、3.4 Fatigue Failure of Fasteners 8 3.3.5 Drive Shaft Failures . 8 3.3.6 Cooling Tower Gearbox Failures . 9 3.3.7 Fin Fan Drive Belt Failures 9 3.4 Loss of Process Performance 10 3.4.1 Loss of Cooling Tower Process Performance . 10 3.4.2 Loss of Fin Fan Process Performance 10 3.5 Assembly Good Practi
24、ce and Repair Guidelines . 10 3.5.1 Aluminium Alloy Cooling Tower Fan Blades 10 3.5.2 Cooling Tower Drive Shafts . 11 3.5.3 Cooling Tower Fasteners . 11 3.5.4 Cooling Tower Drive Assembly Alignment 12 3.5.5 Cooling Tower Gear Box Overhaul 12 3.5.6 Fin Fan Drive Belt Maintenance 12 3.5.7 Cooling Towe
25、r Gearbox Lubrication 12 3.5.8 Fan Balancing . 12 3.5.9 Cooling Tower Gearbox Shaft Restraints . 13 3.5.10 Guarding 13 3.5.11 Flume and Fan Support Structure . 13 3.6 Inspection and Routine Maintenance . 13 3.6.1 Daily checks . 13 3.6.2 Weekly Checks 13 3.6.3 Monthly Checks . 14 3.6.4 Major Mechanic
26、al Inspection - Fin Fans . 14 3.6.5 Major Mechanical Inspection - Cooling Tower Fans 14 EEMUA Publication 215 - Industrial Cooling Tower Fans and Fin Fans EEMUA vi 4. Definitions . 15 4.1 Defined Terms . 15 4.2 Units of Measurement . 15 5. References . 17 Appendix 1 Typical Cooling Tower Fan Assembl
27、y Arrangement 19 Appendix 2 Typical Fin Fan On-Line Inspection Pro Forma . 20 Appendix 3 Typical Cooling Tower Fan Inspection Pro Forma. 22 Appendix 4 Coating of Aluminium Cooling Tower Fan Blades and Carbon Steel Shafts . 24 Appendix 5 Good Practice Design Notes . 25 List of Figures Figure 1 Typica
28、l industrial mechanical draught cooling tower fan . 3 Figure 2 Typical fin fan unit 5 Figure 3 Typical cooling tower fan assembly arrangement . 19 EEMUA Publication 215 - Industrial Cooling Tower Fans and Fin Fans EEMUA 1 1. Introduction This Guide addresses the best design, maintenance and operatio
29、n of mechanical draught cooling tower fans and fin fans used in air cooled heat exchangers. If fans are neglected until they fail, there is often extensive damage to the housing and danger of pieces of blade being thrown out. As well as causing damage to plant, this type of failure presents an unacc
30、eptable risk to the safety of personnel. It is clearly desirable to define and adopt appropriate maintenance procedures. The purpose of this Publication is to set out appropriate maintenance practices. It provides a framework for the maintenance routines and gives details of what is required. 2. Sco
31、pe The scope of this Guide covers mechanical draught cooling tower fans and fin fans as used in industrial air cooled heat exchangers. It excludes small fractional-kilowatt drives provided as part of proprietary equipment, e.g. analysers, laboratory equipment, heating and ventilating systems. The Gu
32、ide does not cover the structural or pressure equipment aspects of the equipment, other than those that directly impinge on the safe operation of the fan. The Guide frequently recommends best practice. This term is used in the sense adopted by the GB Health corrosion of the thin walled steel drive s
33、hafts, leading to their eventual failure, usually near to the couplings; corrosion fatigue of the fine threads on aluminium blades where they screw into the hubs, leading eventually to a blade being thrown out of the hub. The resultant out-of-balance forces may cause further blade failures; rotting
34、of timber blades caused by water ingress through defects in the protective coating; corrosion of the support structure or the fan cowl. In the case of the support structure, the fan blades can touch the cowl and suffer a rapid fatigue failure at the hub; corrosion or attachment failure of the sealin
35、g strip between fin fan banks. The sealing strip then falls and catches the fan blades that then fail due to fatigue; general corrosion of aluminium thin walled cooling tower fan blades, leading to a fatigue failure where the blade internal support tube ends; fin fan failure due to process leakage i
36、n the fan bank leading to ice formation which then falls and hits the fan blades. The blades then fail due to the impact loading. 3.3.2 Water Ingress into GRP Blades GRP blades are generally hollow and if any water accumulates in the blade, the assembly will be thrown out-of-balance and the conseque
37、nt vibration may cause fatigue failures of fasteners. 3.3.3 Fatigue Failure of Fan Blades Fan blades are subject to fatigue loads. For vertical blades there is a gravitational fatigue load, while for all fan blades there are wakes from support structures and non-uniform plenum chambers which cause b
38、ending and torsional fatigue loads on the blades. Blade failures typically occur near the blade root, which is the area of highest load. The failures are associated with blade design (stress concentrations/weld locations) as well as the imposed loads. Contributory factors can also be corrosion or fa
39、stener looseness. One design of cooling tower is to have a concrete tower with horizontal axis fans mounted on the outside blowing air into the packing at the bottom of the tower. A problem with this arrangement is that the fan blades are subject to wind shear, which causes fatigue loading and blade
40、 failure. Solutions found to this problem include fitting higher strength fan blades and to put an external cowl on the fan housing. EEMUA Publication 215 - Industrial Cooling Tower Fans and Fin Fans EEMUA 8 3.3.4 Fatigue Failure of Fasteners Fatigue failure of fasteners, even in the absence of corr
41、osion, has been observed on the U-bolts securing GRP blades to the hub and is attributed to insufficient tightening of the bolts, making them more prone to fatigue under the conditions of vibration which inevitably exist. 3.3.5 Drive Shaft Failures Drive shaft failure modes are of four types. 3.3.5.
42、1 Cooling Tower Drive Shaft Misalignment Drive shaft misalignment puts excessive loads on the gearbox wormshaft bearings or on the intermediate shaft bearings. Seized gearbox bearings can cause drive shaft failure. The controlling factor in shaft alignment is the effect of misalignment on the gearbo
43、x bearings, rather than the capability of the flexible couplings to tolerate the misalignment. Depending on their type and size, flexible couplings will tolerate angular misalignments of 1/4 to 1. On a 2.5 m (8 ft) shaft this corresponds to an offset of 13 mm ( inch) to 45 mm (1 inch) between the mo
44、tor and gearbox shafts. However the achieved alignment should be much tighter than this (see Section 3.5.4). Similarly, the axial alignment of the coupling flanges should be set within the manufacturers specified tolerances, to avoid tension or compression within the coupling elements putting excess
45、ive thrust forces on the bearings. The shaft assembly will normally run at a somewhat higher temperature than the ambient temperature prevailing when it was fitted and so it may be necessary to take into account the effects of thermal expansion. 3.3.5.2 Intermediate Bearing Failure Intermediate bear
46、ings are subject to very difficult lubrication conditions due to the wet conditions they have to operate in continuously. Intermediate bearing failure can cause the drive shaft to separate and contact the fan assembly with consequent fan damage. Best practice is to avoid the use of intermediate bear
47、ings. 3.3.5.3 Delamination of the Drive Shaft Delamination of the drive shaft due to ultraviolet degradation of a non-metallic drive shaft binder material can occur. This is mainly a problem in areas with high levels of sunlight (e.g. Middle East, Gulf Coast). Careful specification of the binder and
48、 coating can help to alleviate the problem. 3.3.5.4 Drive Shaft Erosion Drive shaft erosion arises due to water droplet impingement. EEMUA Publication 215 - Industrial Cooling Tower Fans and Fin Fans EEMUA 9 3.3.6 Cooling Tower Gearbox Failures Gearbox failures rarely result in catastrophic failure
49、of the drive assembly, but there has been at least one case of an incorrectly fitted wormshaft bearing causing a drive shaft coupling failure, and consequent fan blade fracture. Factors causing gearbox failures include: water in the gearbox oil; water in external oil pots (causing water in the gearbox oil); use of the wrong grade of oil; loss of lubricant from leaking oil seals; failure to top-up oil level regularly; fracture or blockage of lubricant pipes etc. due to corrosion; inverting of external oil pot; failure o
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