Guided by: Mr. Gaurav Tiwari

(Manager, A-F Blast Furnace)

Sai SandeepNIT ROURKELA

Study of Poor Life of High Pressure Pumps and

Suggest Recommendations

Project Process Flow:

• Process Flow of Slag granulation system of C BF & D BF• Specifications of HP Pumps

1. Introduction

• Analysis of Pump Life

2. Data Collection and Analysis

• Shop floor brainstorming on key issues • Look for other potential reason for failures

3. Constructing Fault Tree

• Detail out the set of selected recommendations • Check the feasibility

4. Recommendations

Process Flow of Slag Granulation System of C BF & D BF:

C-BF

D-BFSlag

Hot MetalBLOW BOX SLURRY HOUSE

Slurry PumpAgitation Tank

Slurry PumpAgitation Tank

SLAG PROCESSING

PLANT

Slag

Hot Metal

HIGH PRESSURE

PUMP

PRESSURIZED WATER

PRESSURIZED WATER

Specifications of High Pressure Pumps:

Total Number of High Pressure Pumps used = 6 ( 3 Each for C-BF & D-BF)

Pump Details

1 Flow capacity (m3/hour) 900

2 Head of pump(mWC) 50

3 Motor Rating (KW) 220

4 Make Mather & Platt

5 Water Temperature (◦C) 50

• Expected life of HP Pump is 3 to 4 years.

• In actual practice, maximum life is only 2.3 years, average life being 1.8 years.

Analysis of Life of HP Pumps:

D1 D2 D3 C1 C2 C30

0.5

1

1.5

2

2.5

2

1.6

2.32.1

1.7

1.2

1.7 1.8

HIGH PRESSURE PUMP LIFE(in Years)

1st pump 2nd Pump

Pum

p Li

fe (i

n ye

ars)

Maximum

• Cost of a single pump = Rs 5,53,000/-

• Cost of different parts of the pump bought in a single year

= Rs 57,550/-

• Total expenditure for Pumps and spare parts (2012 to 2016)

= Rs 8525200/-=Rs 85,25,200/-

Analysis of Poor Life of HP Pumps:

2015 2014 2013 2012

6

3

1

5

Number of Pumps consumed on yearly basis

Num

ber o

f Pum

ps

Fault Tree Analysis of Pump:Failure of Pumps

No yield

Pump obstructed

Broken shaft

Insufficient yield

Damaged impeller

Worn casing

Unusual behavior

Pump leaks

Pump heats up

Pump vibrates

Fault Tree Analysis of Pump:No yield

Pump obstructed

Strainer blocked due to thrash and Slurry

Vibration due To bad fit

Wrong direction of rotation

Insufficient yield

Damaged impeller

Corrosion

Due to Slurry

Crevice Corrosion

Erosion

Due to Slurry

Cavitation

Low suction

pressureSlur

ry clogged strainer

Resistance too

high due to slurry

Air in

waterMa

noeuvring(Design

)

Fault Tree Analysis of Pump:

Fault Tree Analysis of Pump:Unusual Behavior

Pump Leaks

Damaged Gland

Wear due to slurry

Wrong Assembly

Thermal Shock

Vibration

Pump heats up

Pumping with closed Valve

On 28 /05/2015,HP Pump Room was filled with

slurry water due to leakage by gland

failure

Reasons for Pump failure:

Pump Failure

Pump leakage due to gland

failure

Bearing damage

Pump jam occurs due to blockage

in strainer

Rotating elements like impeller etc.

worn out

Worn Casing due to erosion

The primary cause for failure of pump is the slurry present in the

feed water of HP pump.

What is the source of slurry present in

HP Pump feed water ?

3. HP PUMP RESERVOIR SLAG PROCESSING

PLANT

Suction Tank

P P P P

HP

HP

HP

Make Up Water

CHANNEL

HP PUMP RESERVOIR

Settling Tank

HP

HP

HP

TO C-BF

Blow Box

Flow Diagram Of Slag Processing Plant:

TO D-BF

Blow Box

About 1200 tons per day of slag mixed with pressurized water at blow-box reaches SPP through Slurry pump.

1. Settling Tank

2. Suction Tank

1

2

3

Observations:

In each sample ,it is found that TSS in HP Reservoir input is more than critical value.

On an average 383 ppm of TSS enters High Pressure Pump which is undesirable.

Most of the time ,it is found that TSS in HP Pump Reservoir input is more than Suction tank input.

Study of Samples:

29/05/2015 6/6/2015 11/6/2015 23/06/20150

100

200

300

400

500

600

700

800

900

1000

521

72224

120114 63 131

241

931

177

290

133

Total Suspended Solids (in ppm)

SETTLING TANK INPUT

SGDP SUCTION TANK INPUT

HP PUMP RESERVOIR INPUT

TSS

(in p

pm)

Critical Line for safe

operation of pumps

120 PPM

Substantially High Value

Sample Analysis:Why very high amount of TSS is present in the HP Pump Reservoir input ?

DEPTH=2.35m DEPTH=2.2m

DEPTH=7.2m DEPTH=6.8m

Current system has two settling tanks connected in parallel with a combined volume of 570 metre cube. This gives a retention time of 19 minutes which is inadequate for slurry-water separation.

Frequent cleaning of suction tank is not possible.

Low Pressure pumps present in SPP suck water from the bottom of the suction tank . This is the main reason for presence of high amount of TSS in HP Pump reservoir input.

Dimensions of Settling tank and Suction Tank

Problems caused due to slurry need to be solved not only for the safe operation of HP pumps but also for effective slag granulation keeping the cost and safety issues in mind.

HP PUMP ROOMFloating Particles present in the HP Pump Reservoir

Further problems caused due to slurry:

Recommendations:

Diversion of flow from Parallel to Series in Settling Tank

Use of Coagulants and Flocculants in Settling Tank

Dewatering Silos

Automatic Self Cleaning Strainer

Suction Tank Suction Tank

1.Diversion of flow from Parallel to Series in Settling Tank

SLAG PROCESSING

PLANT

CHANNEL

Settling Tank

Mixture of Slurry and

water From

Slurry House

SLAG PROCESSING

PLANT

CHANNEL

Slurry water

Parallel Flow Series Flow

Settling Tank

2.Use of Coagulants and Flocculants in Settling Tank

Suction Tank

SLAG PROCESSING

PLANT

CHANNEL

P P P P

TO HP PUMP

RESERVOIR

Slurry water

Coagulants will be

dosed here

Settling TankFlocculants

will be dosed here

Visual without chemical addition

Visual with Chemical addition

Observations: The slurry sample with chemical aid showed a much rapid

and better settling as compared to the other one. Initially the slurry had a TSS content of 212 ppm which

was reduced to 52 ppm after the addition of chemical.

3.Dewatering Silos

Suction Tank

Make Up Water

HP PUMP RESERVOIR

P P P P

Dewatering Silos

Slurry goes to

Drier in SPP

Discharge to the Tank = 1500 m3 per hour

Assumptions:Detention Period = 1 hourMaterial is Stainless Steel

Dimensions of the Tank:

Diameter = 16 mHeight of the circular part = 5 mHeight of the conical part = 8 mSurface Area of the tank= 524 m2

CAD MODEL:

4.Automatic Self-Cleaning Strainer

Function:• Continuous removal of entrained abrasive solids

from liquids in pipeline systems

• Integral backwash process controlled by automatic control system monitoring the strainer operation

Straining Cycle: Backwashing Cycle:

Cost

Qua

lity

LOW

HIG

H

Needs Detailed AnalysisInnovative

Trial Purpose

LOW HIGH

1.Diversion of Flow from parallel to series in settling tank

2.Use of Chemicals in Settling Tank

3.Dewatering Silos

4.Automatic Self Cleaning Strainer

Feasibility Study on the basis of PQCDSM:

Productivity (P) Reduction in breakdownsQuality (Q) Extent of Slurry-water

separationCost (C) Initial investment Maintenance CostDelivery (D) Reduced inventory stockSafety (S) Zero accidentsMorale (M) Increase in improvement

ideas Increase in small group

meetings

Learnings of the Project:

Got brief idea about Blast Furnace Operation and Slag Granulation System

Doing Fault Tree Analysis

Learned how to utilize and take information from the people of shop floor

Application of MATLAB and CATIA to solve practical problems

Thank You

UnderGround Tunnel

SLAG PROCESSING

PLANT

Process Flow:Charge

Hot Air + Coal Injection

Hot Metal Torpedo

Slag

Blow Box

AgitationTank

SP

SP

Suction Tank

P P P P

HP

HP

HP

Make Up Water

CHANNELHP PUMP RESERVOIR

PRESSURIZED WATER

Settling Tank

D-BF

HP

HP

HP

TO C-BF

Blow Box

D-1 H. Pr.Pump 9-Feb-12 9-Jan-14Rotating eliment 4-Sep-15

D-1 NRV

D-1 NRV Ball

D-1 Del valve 1-Aug-14D-1 Del bend 13/09/14

D-2 H. Pr.Pump 7-Jul-12 20-Jan-14 26-Sep-15D-2 NRV 14/05/15

D-2 NRV Ball 16/12/13 26/03/15

D-2 SUC VALVE 16/01/14

D-2 Del bend 27/09/14 2 no.

D-3 H. Pr.Pump 23-Feb-11 25-May-13 25-Feb-15D-3 NRV

D-3 NRV Ball 25.03.15D-3 Del bend 29.09.14 2 no

D1 Line

D2 Line

D3 Line

C-1 H.Pr. Pump 31.08.12 26.09.14C-1 NRV 04.11.13C-1 NRV Ball 31.12.12 23.10.13 08.05.15

C-2 H.Pr. Pump 16.02.12 26.10.13C-2 NRV 25.02.14C-2 NRV Ball

C-2 DELV VALVE 21.03.14

C-3 H.Pr. Pump 10.09.11 10.11.12Rotating eliment 10.06.14

C-3 NRV 20.02.13C-3 NRV Ball 13.11.12

C1 Line

C2 Line

C3 Line

39%

21%

16%

15%6%3%

Breakdown of D Furnace since NOV 2014(in terms of hours)

CAST HOUSE STOVES CHARGING SGDPSTOCK HOUSE OTHERS

SGDP

33%

26% 15%

12%11%

3%

Breakdown of D Furnace since NOV 2014(in terms of frequency)

CAST HOUSE CHARGING STOVESSTOCK HOUSE SGDP OTHERS

SGDP

Feasibility Study on the basis of PQCDSM:

Recommendations 1.Diversion of Flow 2.Use of Chemicals in Settling Tank 3.Dewatering Silos 4.Automatic Self

Cleaning Strainer

Productivity (P) Reduction in breakdowns 5 9 10 8

Quality (Q) Extent of Slurry-water separation 5 9 8 7

Cost (C) Initial investment Maintenance Cost

10 4 6 7

Delivery (D) Reduced inventory stock 6 9 9 7

Safety (S) Zero accidents 10 7 9 10

Morale (M) Increase in improvement ideas Increase in small group meetings

5 9 9 9

Total 41 47 51 48

Design and Calculations for Dewatering Silos:

Given:Material of the tank is Stain less steelDischarge to the tank (Q) =1500m3 per hourVolume of the tank (V) = Q × t…………………………………………...eqn (1)where, t is the detention period.Generally, Detention Period is 1-3 hours.Assumption:t= 1 hourD be the diameter of the tankh be the height of the conical part of the tankH be the height of the circular part of the tankTVH be the total vertical height of the dewatering silos Cross sectional area of the circular tank (A) = (Π/4) × (D2)…..eqn(2)

Total Volume of the tank = Volume of the conical part + Volume of the circular part V= Taking common in RHS,V= From eqn (1) & eqn(2) ,We getQ By rearranging the above eqn,h=TVH= H+h

By assuming different values of D and H we can design the tank. To optimize the size, height and surface area of the tank, MATLAB program has been executed which is shown below.

The above program gives following results:D=16m,H=5m,h=8m,TVH= 13m,Surface Area = 524 m2

From design tables with reference to Underwriters Laboratory, Inc., UL 142, "steel aboveground Tanks for Flammable and Combustible Liquids." (1984)We get the thickness of the tank = 2 cm CHECK-1:Hoop’s stress on the walls of the tank:Ϭ= (ρ ×g × h× D) / (2×t)Where, Ϭ= hoop’s stress ρ= density of the water, 1000 kg per m3

g= acceleration due to gravity, 9.81 m/s2

h= TVH, 13m Ϭ hoop’s stress found to be 51 MPa which implies that it is a safe design.

CHECK-2:Settling Velocity of the slurry particles:Density of suspended particles (ρp) =2650 kg/m3;Density of water (ρ) =984 kg/m3;Dia of particles (Dp) = 0.5mm;Viscosity (µ) =0.4658 milli Pa-sec;

Settling Velocity of particles in Laminar Flow

18

)()(

2pp

s

DgV

Reynold’s Number (Re)=514.728As 1<Re<104, the flow is transitional.

Coefficient of Drag (Cd)= +0.34=0.5189

24

Re 21

)(

3

eR

Settling Velocity of Spherical Particles =0.1461m/s

Cd

Dg pps 3

)(4)(

After several iterations, we found the value of converges as 0.1175m/s.Minimum up flow velocity (Vu) =Q/A=0.00207m/sAs Vs>Vu, sedimentation of particles will occur easily.Hence, our design is safe.

CAD MODEL & DRAWINGS: