REF: FGD:AGITATORS
TECHNICAL SPECIFICATION OF
AGITATORS REV. No. 01
A) For Horizontal (Side Entry) Agitators:
Sl. Scope
No
1. AGITATOR complete with
i. AGITATOR Blades
ii. AGITATOR Shafts
iii. Coupling arrangement (Flexible)
iv. Single Mechanical Seals
v. Shaft Sleeve
vi. Lanterns/ Stools ( Bearing Housing), Safety Guard
vii. Bearings
viii. Agitator Mounting Flanges with gaskets and fasteners
ix. Drive Motor(IE3) with gearbox / belt and pulley arrangement
x. Supporting arrangement of Side Entry Agitator on the tank Wall.
xi. Flushing system for start up consisting of Pipe with Flange . Gaskets and Fasteners to be
provided for mounting the flush pipe on the Tank Nozzle
xii. Foundation plate with foundation bolts
xiii. Painting and Rust Prevention during shipment and construction
xiv. Supervision of Erection & commissioning at site
xv. Special tools & tackles as applicable
xvi. Start-up and Commissioning Spares as applicable
xvii. First fill Lubricants
xviii. Installation, operation and maintenance manuals
xix. Any other items required for completeness of the equipment except the items covered in
the exclusions.
B) For Vertical (Top Entry) Agitators :
Sl. Scope
No
2. AGITATOR complete with
i. AGITATOR Blades
ii. AGITATOR Shafts
iii. Coupling arrangement (Flexible)
iv. Gland Packing, Seals, O Rings, Glands
v. Shaft Sleeve
vi. Lanterns/ Stools ( Bearing Housing), Safety Guard
vii. Bearings
viii. AGITATOR Mounting Flanges with gaskets and fasteners
ix. Drive Motor(IE3) with gearbox/ belt and pulley arrangement
x. Mating Flange for Supporting on Slurry Tank Roof
xi. Painting and Rust Prevention during shipment and construction
xii. Supervision of Erection & commissioning at site
xiii. Special tools & tackles as applicable
xiv. Start-up and Commissioning Spares as applicable
xv. First fill Lubricants
xvi. Installation, operation and maintenance manuals
Page 7 of 37
BIDDER SIGN WITH SEAL AND DATE:
REF: FGD:AGITATORS
TECHNICAL SPECIFICATION OF
AGITATORS REV. No. 01
Sl. Scope
No
xvii. Any other items required for completeness of the equipment except the items covered in
the exclusions.
5.1 TECHNICAL REQUIREMENTS
Agitators shall be supplied in tanks and vessels to prevent caking and settlement of particles
1. out of the slurry, e.g. in the absorber vessel, limestone mill recycle tanks,
limestone slurry tank, Auxiliary Absorbent tank, and sumps etc.
All agitators shall be designed for continuous operation unless otherwise specified.
2. The design of the agitators shall be of proven type. CFD analysis, if required, shall be
provided during Offer stage or drawing approval stage at no extra cost.
Standard type agitators with suitable characteristics shall be used wherever practical. The
agitators shall be complete with motor, gearbox, agitator shaft, coupling, safety guards,
3.
mechanical seal (for side entry agitators), impeller, support legs, agitator mounting flange
including bolts nuts and gasket etc.
All agitator parts and accessories in contact with the stirred fluid shall be constructed of
4. materials specifically designed for the conditions and nature of the stirred fluid and be
resistant to erosion and corrosion.
MOC of various agitator parts shall be as per /Agitator
selection Criteria . This does not release the bidder of the responsibility for selecting the
5. correct materials. All parts which are in contact with slurry or in contact with slurry fumes
shall be considered as wetted part. The material selected shall be suitable to the service
conditions.
Each agitator and its associated equipment shall be arranged in such a manner as to
permit easy access for operation, maintenance and agitator removal without
6.
interrupting plant operation. It shall be possible to remove the sealing devices of the
absorber vessel without having to drain completely the absorber.
To prevent mechanical blocking load start-up after standstill of pumps, piping and
7.
agitators for slurries shall be applied with C-hose connection.
Lifting lugs and eyes and other special tackle shall be provided as necessary to
8.
permit easy handling of the agitators and their components.
Static and dynamic (as far as applicable) balancing of all agitators shall be carried
9.
out after assembly.
All agitator parts and components shall be designed and calculated for fatigue life,
considering maximum bending loads, induced by fluctuating hydraulic forces and
10. torsional loads, based on the installed motor power. For side entry agitators the
alternating bending moment resulting from impeller and shaft weight has to be
considered additionally.
11. All exposed moving parts shall be covered by guards.
The shape of the impeller blades of side entry agitators shall be designed to avoid
wear on the impellers which will affect the agitator performance as specified for a
12. minimum period of 2 years of continuous operation under design conditions for the
range of coal & limestone specified in the specification. In order to avoid excessive
wear impeller tip speeds must not exceed 12 m/s
Page 8 of 37
BIDDER SIGN WITH SEAL AND DATE:
REF: FGD:AGITATORS
TECHNICAL SPECIFICATION OF
AGITATORS REV. No. 01
Belt drives (if applied) shall be properly designed to provide a minimum lifetime of 2
13.
years under design conditions
It shall be noted that all Agitators (except Absorber Agitator, Auxiliary Absorbent Tank
Agitator and Drain Sump Agitator) are meant for keeping the solid particles in suspended
14.
Uniform
No chemical reaction will take place.
For Absorber, Auxiliary Tank and Drain Sump Agitators : There shall not be any slurry
15. settlement at the Bottom of the Tank and all solids shall be suspended off the tank bottom
(i.e. Off Bottom suspension)
It is to be noted that in continuous process any deposit at tank bottom is the loss of material
16. which are not getting converted as per process. Hence, total loss of material by
Vendor should ensure nil settlement; utilization of solid material shall be a guaranteed
17. parameter and will be assessed in percentage (%) term to net wet of solid mass of inflow or
out flow. This is one of the guarantee parameter.
permanent location at site within vibration limit the vibration of combined unit will be the
18. responsibility of Agitator manufacturer. Agitator manufacturer is to ensure that Site
note
vibration at test stand can only be taken as for information.
Impeller shall be kept above the sedimentation level of the tank (just 100-200mm above the
19.
sedimentation level).
Agitator must have low-pitch propeller with low solidity ratio and low Power Number.
Power number shall 0.35 or lower. The Maximum Input Power at motor terminal shall be
Annexure-V-Schedule of Guarantees - and the same shall be calculated for maximum liquid
level in tank. A calculation of power specifying the hydraulic power of Agitator, Seal loss,
20.
Gear box and Motor internal loss must be submitted along with the offer. A characteristics
curve showing power versus liquid level should be submitted from the lowest liquid level,
required for Agitator to maximum liquid level in the tank. Motor should be selected based
on the highest power demand with a margin as per clause 5.3.1 at maximum liquid level,
taking into account frequency variation.
Bidder shall provide the design and arrangement of baffle plates in circular tanks.
21.
Baffle plates are in BHEL scope.
5.2 CONSTRUCTIONAL FEATURES
A) BLADE AND HUB OF PROPELLER
The type of impeller shall be selected on the basis of suspended solids where the work is
i) being performed. The selected profile shall be consistent with the specified operating
conditions ,i.e., the type of tank, solid concentration,etc.
ii) It must be possible to remove the blades from their joining point. Each blade shall be made
of one single piece.
The Blade design of the Agitator to be of most efficient design in order to offer least power
iii)
consumption. The Agitator power consumption is part of the guarantee parameters.
Although Agitator will have substantial low speed because of reduction Gear Box, hydraulic
iv) unbalance at impeller can cause severe vibration, hence it is mandatory that rotating
assembly shall be dynamically balanced to its rated speed.
Page 9 of 37
BIDDER SIGN WITH SEAL AND DATE:
REF: FGD:AGITATORS
TECHNICAL SPECIFICATION OF
AGITATORS REV. No. 01
Impeller should be dynamically balanced to Gr: G16: ISO-1940 after rubber lining of shaft
v)
(wherever applicable)
For circular tanks with Top Entry agitator, the tip diameter of the impeller shall be one-third
vi) of the Tank diameter.
For circular tanks with Top Entry agitator, Two level of impellers have to be offered for
achieving uniform suspension if both the following conditions are satisfied:
a) (Slurry Filling Height X specific gravity)/Tank Dia >1,
b) (Slurry Filling Height X Specific Gravity)/ Impeller Tip Dia > 4.
vii)
The tip diameter of both the impellers have to be same for maintaining uniform
suspension(if uniform suspension is applicable). Bidder shall refer to the Technical
Information of Agitator/Agitator Selection Criteria where two level of impellers are required
for tanks with Uniform Suspension.
However, bidder may propose two level of impellers for other tanks if their standard design
permits the same.
B) SEAL
1. Horizontal / Side Entry Agitators:
I. Agitators should be provided with Single Stage mechanical seal. the mechanical seal should
be as per ISO-21049 / API 682
The Mechanical Seals shall be so arranged that repacking or fitting of replacement seals can
II.
be carried out with the minimum of disruption to plant operation.
Design the mechanical seals chamber to have sufficient room to lubricate and get seal face
III.
cool with its own slurry.
IV. Provide requirements for periodical flushing to rinse the seal face for leaked slurry.
All mechanical seals, regardless of type or arrangement, shall be of the cartridge design.
V.
Hook sleeve cartridge should not be used.
VI. Requirement of flushing water, its quantity, and pressure to be indicated in data sheet.
Zero leakage is the intension of this specification. However, quantity of leakage, if it is
VII.
unavoidable, it should have a provision of collecting / or discharging back to the tank.
Mechanical seals shall be fitted and installed in the Agitator before shipment and shall be
VIII.
clean. Mechanical seals shall be plugged with screw for shipping.
Intention of the specification is not to specify Type of Seal, Seal design, Spring configuration,
IX. Seal configuration, Balanced or Unbalance type etc. Agitator manufacturer to decide the
same along with seal manufacturer the best seal that is suitable for the offered Agitator
Seal life has to be guaranteed, taking into consideration all its components for 20000 hrs. If
X. the seals fail before the completion of guaranteed period, the same should be replaced free
of cost by the bidder.
XI. The sub-vendor of the seal shall be approved by END CUSTOMER during contract execution.
Page 10 of 37
BIDDER SIGN WITH SEAL AND DATE:
REF: FGD:AGITATORS
TECHNICAL SPECIFICATION OF
AGITATORS REV. No. 01
2. Vertical Agitators for Other Slurry Tanks & Drain Pit Tanks
Agitator shall be supplied with stuffing box or Labyrinth seal or any proven equivalent or
superior sealing type.
Mechanical and hydraulic conditions in the seal chamber, required to maintain a stable film
I at seal face, including temperature, pressure and flow, shall be jointly established by
Agitator manufacturer and seal manufacturer, and shall be noted in data sheet submitted in
tender. If mechanical seal is offered by bidder, the mechanical seal should be as per ISO-
21049 / API 682.
C) SHAFT
Use of dissimilar material at flange joint shall be avoided to eliminate any crevice corrosion.
Spacing of the shaft joint should not be more than 3.0 m (preferably) for easy assembly if it
is more than 40kg. If welding is used for joining two tubes, welding joint must be 100%
radio graphed. If split shaft is proposed for larger tanks , shaft flange at the joining interface
y fasteners have to be
provided. All the connecting fasteners shall be Alloy 926 or better material. All the Fasteners
coming inside the tank (below the Mounting base or Mounting flange) shall be Alloy 926 or
better material.
D) BEARING & BEARING HOUSING IN GEAR BOX
Bearing shall be of rolling type radial and thrust bearing (FAG/SKF make only) as required.
Thrust bearing shall be sized for continuous operation under all specified condition.
Thrust bearing shall provide full load capability if the Agit
is reversed. Up-thrust and Down-thrust load must be taken into account in sizing bearing.
Life of every anti-
should have L10 of 25000 hr (minimum).
None of the Shaft bearings shall be allowed to be inside the tank or drain.
Bearing housing should be grease/oil lubricated. If bearing is oil lubricated, constant level
sight-feed oiler of 100cc size or bigger capacity is to be provided. Bearing housing should
have oil drain, constant oil level indicator. A provision of one(1) number -
228,Part-1)port is required for remote control of temperature of bearing housing oil bath
RTD.
If bearing housing requires cooling water, volume and pressure of cooling water is to be
indicated in Technical Data Sheet.
Lubricating oil will be the responsibility of Gear Box manufacturer. Hence, manufacturer has
to make arrangement of first fill of oil at installation and at commissioning stage. Quantity of
oil and its grade is to be indicated in Drawing and Operation Manual.
E) MATERIALS
requirements of the industry specification as listed for the material in the table as
well as in the specification in the respective section.
Final acceptance of the quality plan will be approved by ultimate user (hereafter
called END CUSTOMER). Hence, it is expected that manufacturer to submit quality
Page 11 of 37
BIDDER SIGN WITH SEAL AND DATE:
REF: FGD:AGITATORS
TECHNICAL SPECIFICATION OF
AGITATORS REV. No. 01
plan (QAP) along with the offer. The same shall be followed at post order stage also.
QAP should be as per the best practice followed internationally to avoid any conflict
of interest.
F) Driver ( Motor)
Driver shall be sized to meet all specified operating conditions including bearing
1
housing , seal, external gear box and coupling loss( if any).
Motor shall be able to accelerate to speed at reduced voltage and frequency as
2
Clause: 4.1.
3 It should meet Motor specification enclosed.
G) GEAR BOX
Gear box should be vertical flange mounted solid shaft type (Vertical Agitators),
reducing speed type, specially designed for the requirement of Slurry mixing and to
be manufactured by the Agitator supplier. Complete up-thrust and down-thrust,
developed by Agitator shall be taken by thrust bearing housing of Gear Box. Gear
Reducers shall confirm to AGMA standard as follows:
A. 1.25 Service Factor based on Motor Horsepower
B. 1.5 Service Factor based on calculated brake Horsepower
H) COUPLING & COUPLING GUARD
Coupling and coupling guard should be supplied between driver and driven
I.
equipment.
II. Coupling should be designed taking into consideration adequate service factor.
Design rating of the coupling (excluding service factor) should be indicated in data
III.
sheet.
Coupling must be having locking screw so that it does not slide over shaft in due course
IV.
operation.
Vertical Agitators - Coupling between Motor and Gear Box shall be Spacer-type flexible
coupling, made of Cast Iron. Spacer length shall be of sufficient length so than Motor and
V.
Gear Box shall be able to run independently at no-load condition by detaching the
respective coupling.
It is desirable that for servicing of seal, coupling half should not be removed. Coupling
VI.
should be dynamically balanced to Gr: G6.3, ISO-1940.
Removable coupling guard shall conform to the requirements of all applicable national,
VII.
industrial or statutory regulations.
I) PLATE AND FASTENING BOLTS
Base plate shall be interpreted as the component of Agitator assembly through
which the whole load will be transmitted to the Sole Plate/Nozzle over which the
I. equipment will be mounted. The Base plate shall be fabricated with mild steel of
structural quality (UTS=42N/sq mm minimum) with anti-corrosive paint of sufficient
dry-film thickness.
II. Base plate must have provision of leveling on its intended mounting place. Sole plate
Page 12 of 37
BIDDER SIGN WITH SEAL AND DATE:
