Rendezvous With Bhel

8/8/2019 Rendezvous With Bhel

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RENDEZVOUS WITH BHEL:

I was too thrilled & felt extremely joyous to pursue my vocational training at such a bigenterprise in the field of Indian industries. I was really looking forward to my vocational

training as an interface between my theoretical knowledge & its technical application.

In the very first look, B.H.E.L seemed to be far big than the general perception I hadabout an industry. B.H.EL is a self sufficient city in itself giving a reflection of thegrowing industrial manufacturing standards in India.

ARRIVAL:

As directed, our group had to report at Human Resources Development Centreof

the B.H.E.L to get ourselves enrolled with the B.H.E.L for the training & to get our

security passes. We were received by Mr. Balodhi, Incharge Human Resource

Development Department & then sent to the respected offices. The wholeenvironment was giving an impression of true professionalism.

All of us were sorted in different groups & assigned different blocks. With three other

people in the group I was assigned BLOCK 3 TURBINE MACHINES.

Our field of training was General Awareness in Steam Turbines Machining &

Their Assemblies under the able guidance of Mr. Subroto Haldar, Deputy

General Manager Block 3.

MANUFACTURING UNIT:

Our First day at the B.H.E.L got consumed for the paper work, formalities & issuing ofsecurity passes. All my excitements were jumping out of my limits to enter the

manufacturing unit which could happen only on the second day. As directed at H.R.D.D,

we reported to Mr. Subroto Haldar at Block 3.

We were received by him in very professional & obliging manner. He familiarized us

with all the works & operations as well as the different machine tools & processes being

carried out in the Block-3. He gave us the general layout of the block comprising ofdifferent Bays. He also provided us with the Route Sheet containing the information

about our four weeks training and the trainers we had to report to.


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FIRST WEEK

BAY 1


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As per the information in the route sheet we had to report to Mr. Gulati for the first week

of our training in the Bay 1.

Mr. Gulati gave us a brief description of bay 1 which comprised of different kinds ofBoring & Drilling machines. We were directed to visit each of the machines in the bay &

get the information about their working, operations, material flow, workers & working

conditions. We were instructed to communicate with workers & supervisors working ondifferent machines. In case of any queries which could not be answered by these people,

we were told to contact Mr. Gulati who was always ready with the answers.

BAY-1 LAYOUT

MACHINE SPECIFICATIONS


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In Bay-1, we got good exposure to many state of the art technology Drilling & Boring

machines. Some were much bigger than that we had expected. We got opportunity tomachine parts on our own under the supervision of the supervisors. We drilled holes on

various turbine parts such as Guide Blade Carriers, casings (inner, inner-outer, outer).

Apart from turbine parts we also drilled holes in some of the valves, breech nuts etc.Out of all the machines there was a machine which stood tall in terms of size as well as

technology. This machine was a Vertical Boring Machine manufactured by an Italian

company Carnaghi Pietro.


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THE LEADING ASSET OF BAY 1

Carnaghi-Pietro Vertical Boring Machine


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Major Specifications:

Machine Model AP 80 TM-6500

Table Diameter 6500 mm

Max. Turning Diameter 8000mm

Min. Boring Diameter 660 mm

Max Height for Turning & Milling 7000 mm

Table Load Capacity 200 Tons

Table Speed 0.2 to 50 R.P.M

Milling Spindle Speed 3.4 to 3000 R.P.M AT 40 KW

Spindle Taper BT 50

CNC System Sinumerik 840D

Special Features:

Automatic job measurement for measurement of machined dimensions using

electronic probes.

Automatic tool offset measuring system for measurement & storage of tool offset

values in the systems memory.

Auto focus video camera with color monitor to view tool / dial whilemachining / setting of casing.

Vertical milling head

Max height for milling 7000mm

Max cutter diameter 250mm Universal milling head

Max height for milling 6700mm

Max cutter diameter 250mmAutomatic swiveling +90deg to -90deg in vertical plane

Min increment for automatic swiveling 0.001deg

Swiveling accuracy +/- 10 secCost per hour RS.11000


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Reduction in machining time

Product Componentdrawing no.

Old time(hours)

New time(hours)

Percentagereduction

Gas turbine

V94.2

Centre casing

07360302000

300 220 26.6

Steam turbine

500 MW

H.P. outer

casing

01050109500

384 272 29.1

Steam turbine

500 MW

H.P. inner

casing

0105020900091010745051

784 600 23.5

Steam turbine500 MW

I.P. inner casing01060227000

91020445051

358 305 14.8


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WEEK TWO

BAY 2


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After acquiring adequate knowledge about various boring & drilling operations

beings performed in Bay-1 as well as the machines we had to report in second week to

Mr. S. Bajaj who was our instructor for Bay-2. He introduced us to the bay with the sameprofessionalism as by Mr. Gulati & gave us the same instructions.

Bay -2 comprised of C.N.C, D.N.C Lathes, & few Drilling, Milling & Planer machines.

BAY-2 LAYOUT

MACHINE SPECIFICATIONS

Out of all the above mentioned machines of Bay-2, there was a machine which was

unique in its features & could perform on its own almost all the operations being carried

out in the bay. This was INNSE BERARDI, the C.N.C Lathe Machine.


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TECHNOLOGY AT PAR WITH EXCELLENCE

INNSE BERARDI


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THIRD WEEK

BAY-3

ASSEMBLY SECTION


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INTEGRATION OF TURBINE PARTS

The first two weeks of our training were quite educative & informative giving us an apt

knowledge of almost all the known machines & machining techniques being used at bays

1 & 2 of Block- 3. So far, we had only seen various machines & turbine parts (workpiece) being machined on them. Till this stage, we could identify all the parts of the

turbines & now it was the time for us to know about the assembly of these parts to form

the turbine.

As per our route sheet, for our third week of training at Bay-3 i.e. Assembly Section we

had to report to Mr. Saxena, whose behavior towards us was no different from others.Now it seemed to us that pure professionalism is one of the main characteristics of all the

B.H.E.L employees irrespective of their post.

Mr. Saxena introduced us to assembly section in a bit different way. He personally tookus to different stands (where turbines of different wattages were assembled) & explained

us that which one is for which kind of turbine. We could see around ten stands in all

marked with the specifications for the turbines ranging from 250MW to 1000MW forassembly of Gas, Hydro & Steam Turbines. But due to non availability of orders only one

stand was being prepared to carry on the assembly work. Mr. Saxena told us that

assembly of a 500MW Low pressure steam turbine would start the next day on which wehad to report at Bay-3 & so he decided to take a theory class on Day 1.

MR. SAXENAS LECTURE:

Although being in manufacturing industry since many years, Mr. Saxena, possessing a

degree of Masters in Engineering, delivered very meticulous. His topic was turbines. Heenlightened us about three types of steam turbines which could be assembled in Bay-3

viz. Low pressure turbine, Intermediate pressure turbine & high pressure turbine. To start

with, he told that a turbine plant consists essentially of all the three kinds of abovementioned turbines, a generator & a governor.

BLOCK DIAGRAM


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The whole set up is laid up as shown in the block diagram. The three turbines, generator

& the governor are connected to each other with shafts further being connected bycouplings.

Steam first of all enters H.P Turbine which on one side is coupled to governor & on theother side to I.P Turbine. H.P Turbine has the smallest of the dimensions of the three

turbines. Steam after expanding through H.P Turbine is supplied to I.P Turbine

(intermediate dimensions) which is supplied with additional steam also. Steam nowexpands through I.P Turbine & is fed to L.P Turbine (max. dimensions) where it is

further expanded. Additional steam is also fed to L.P Turbine. The over all expanded

steam is taken out from a valve of L.P Turbine. This whole procedure generates torque in

the interconnected shafts of the three turbines & this torque is further transmitted to therotor of the generator & thus electricity is obtained. With all such details, two & a half

hour long lecture of Mr. Saxena ended.

ASSEMBLY of 500MW L.P STEAM TURBINE at ASSEMBLY

STAND NO. B.H.E.L/BL-3/BAY-3/3

On our second day at Bay-3, we were instructed to move directly to the assembly stand.In the first site we could see an L.P Inner Outer Lower Half Casing clamped on the stand.

A senior supervisor being called upon as Master Ji took us in his charge. He was

supervising the whole assembly progress. He kept explaining us the various activitiesbeing carried out during assembly. First of all, a large over head crane came with L.P

Inner Outer Upper Half Casing which with much labour made to sit accurately on lower

half & further was clamped on the stand & also fitted on lower half using bolts & nuts.The whole procedure took around one & half hour & it seemed to us that three hoursallowed time for training was not enough to understand the full assembly process. We

talked about this to our incharge Deputy General Manager Mr.S.Haldar and got our

training time extended from three hours to six hours till our training in assembly sectionwhich could be implemented from third day only because of various security checks.

On our third day at the assembly stand, a dummy rotor was installed at the center of innerouter casing using various gauges to rule out any possibility of it getting offset from

center point of inner outer casing. Further, the overhead crane brought Guide Blade

Carriers-1(G.B.C-1) to be fixed on first bored ring of Inner Outer on both sides. Again

the G.B.Cs-1 were brought in two parts viz. upper halves & lower halves & the work tofix G.B.Cs started. G.B.Cs one by one were first clamped to Inner Outer at their

respective bored rings with reference to dummy rotor & were bolted using pneumatic

bolting gun.

On the fourth day in Bay-3, G.B.Cs 2& 3 were fixed in the same manner.


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On the fifth day, upper half of the whole assembly assembled till now was lifted by a

crane & L.P Inner was made to sit on the platforms of lower assembly & the upper half

was again bolted.

On our last day in the bay the whole assembly was enclosed in L.P Outer Casing Lower

& L.P Outer Casing Upper & by the time we left at our timings bolts were still beingbolted. We were told that the rotors are fixed only at the site of the installation of the

turbines.


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FOURTH WEEK

O.S.B.T


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Till now in the three weeks of our training , we had seen only machining of various

turbine parts & their assembly. But in the fourth week we were directed to go to Mr.

Sheesh Ram in the O.S.B.T . The term O.S.B.T was very new for us & only after talkingto Mr. Sheesh Ram, we got to know that it was a over speed vacuum balancing tunnel, a

set used to balance the rotors to prevent vibrations. So it was our first chance to see the

inspection work.

The H.E.E.P unit of B.H.E.L, Hardwar is having two balancing facilities known as over

speed balancing installation located in Block-1 (O.B.-1) & the other one located inBlock-3 (O.S.B.T ) called as over speed vacuum balancing tunnel. As we were in Block-

3, so we only got the chance to see O.S.B.T.

Although, like each component made at B.H.E.L. with precise accuracies due to use ofC.N.C machines, rotors are also made with state of the art technology but then also due to

some unavoidable errors, even difficult to be detected by C.N.C machines, the rotors

produced are not fully balanced. Unbalanced rotors lead to vibrations of rotors as well as

the whole turbine at the time of operation. As we know, the vibrations have major illeffects on the efficient functioning of any machine or set up they have to minimize &

O.S.B.T performs this function for the rotors.

O.S.B.T. basically is a vacuumized tunnel equipped with all the facilities to balance a

rotor. Vacuum is created as while balancing rotors are rotated at very high R.P.Ms & the

presence of air would develop great friction & thus would cause damage to the rotorblades.

To start with the balancing, the first major task is to bring the rotor to the O.S.B.T & thepurpose is served by the two Pedestal Bearings which are made to move out of O.S.B.T

through rails at the place where rotor lies. The rotor is fixed on the bearings using a crane

& then the whole set up is moved inside the O.S.B.T & the front wall of tunnel ishydraulically pressed against the wall of tunnel. Now, the entry could be made to the

tunnel by only one small rear door. Once, the rotor is brought inside O.S.B.T its

monitoring starts in a separate big hall outside the tunnel using various advancedmachines & multi screen system.


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BLOCK DIAGRAM

The position of the rotor is monitored by two screens, on which the virtual views of front

& rear faces of the rotor ends appear. Position of both the ends of the rotor is marked on

the screen at the X & Y Axes. After this, workers in the tunnel are directed to make the

adjustments as per the calculations made in the control room & the rear door of the tunnelto generate the vacuum. The vacuum in the tunnel is generated by using vacuum pump &

the vacuum pump keeps on doing that until a vacuum of 2 torr is achieved in the tunnel.

This process of creating vacuum in the tunnel may take from two to three hours. Now therotor is made to rotate with the help of a set up installed outside the O.S.B.T. comprising

of two large D.C. generators each having a capacity of 2x3.8 MW. These generators are

connected to the motor which rotates the carton shaft. The carton shaft is in turn coupledwith the rotor thus rotating the rotor at high speeds. The rotor is made to rotate at about

3000 R.P.M which is the balancing sped for the rotor. The vibrations are generated in the

rotor which can be analyzed along the four axes (+X, +Y, -X, -Y ) on the two screens inthe control room. To eliminate the vibrations in the rotor, weights are applied to the

opposite axis of the vibration. To put the correction weights on the rotor, the wholearrangement is brought to a halt. This process is continued till we get sufficiently low

value of vibrations at 3000 R.P.M. Although the rotor is balanced at 3000 R.P.M but it isrotated at much higher speeds up to 3750 R.P.M which is the maximum limit of the speed

of rotors in order to put them on an overspeed test so that the rotors do not fail while

operating in the industries. This is known as OVERSPEED BALANCING of a ROTOR.

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Rendezvous With Bhel