hydraulics in vizag steel plant

Modification of Furnace Hydraulic System in M.M.S.M

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1. INTRODUCTION TO VISAKHAPATNAM STEEL PLANT

(VSP)

Visakhapatnam Steel Plant, the first coast based Steel Plant of India is located, 16km

south west of City of Destiny i.e., Visakhapatnam. Bestowed with modern technologies, VSP

has an installed capacity of 3million tones per annum of liquid steel and 2.656 million tones

of saleable steel. At VSP there is an emphasis on total automation, seamless integration and

efficient up gradation, which result in wide range of long and structural products to meet

stringent demands of discerning customers within India and abroad. VSP products meet

exalting International Quality Standards such as JIS, DIN, BIS, BS, etc.

Vsp successfully installed and are operating efficiently Rs. 460 crores worth of

pollution control and environment control equipments and converting the barren landscape by

planting more than 3 million plants. Vsp exports quality pig iron and steel products to

Srilanka, Myanmar, Nepal, middle EAST, USA, and south east Asia (pig iron). RINL-VSP

was awards “star trading house” status during 1997-2000. Having a total manpower of about

16,613 vsp has envisaged a labour productivity of 265 tons per man year of liquid steel which

is the best in the country and comparable with the international levels.

1.1 MAJOR UNITS:

DEPARTMENT ANNUAL CAPACITY

(1000T)

Coke ovens 2,261

Sinter plant 5,256

Blast furnace 3,400

Steel melt shop 3,000

LMMM 710

WRM 850

MMSM 850

Table 1.1


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1.2 MAIN PRODUCTS OF VSP:

STEEL PRODUCTS BY-PRODUCTS

Angles Nut coke – Lime fines

Billets Coke Dust – Ammonium

Channels Coal Tar - Sulphate

Beams Anthracene oil

Squares HP Naphthalene

Flats Benzene

Rounds Toluene

Re-bars Xylene

Wire rods Granulated slag

Table 1.2

1.3 MAJOR DEPARTMENTS:

1.3.a Raw material handling plant (RMHP):

Vsp annually required quality raw materials of viz.., iron ore, buxes (lime stone,

dolomite), coking and non-coking coals etc to the tune of 12 to 13 million tons for

producing 8 million tones of liquid steel. To handle such a large volume of incoming raw

materials received from different sources and to ensure timely supply of consistent quality

of feed materials to different vsp consumers, RMHP serves a vital function. This is

provided with elaborate unloading, blending, stacking and reclaiming facilities. In vsp

peripheral unloading has been adopted for the first time in the country.

1.3.b Coke ovens in coal chemical plant (co & ccp):

Blast furnace, of any steel plant required huge quantities of strong, hard and porous

solid fuel in the form of hard metallurgical coke for supplying necessary heat for carrying out

of the reduction and refining reactions.

Coke is manufactured by heating of crushed cooking coal (below 3mm) in

absence of air at temperature of 1000’c and above 16 to 18 hours. At vsp there are three coke

oven batteries, 7 meter tall and having 67 ovens each. Each oven is having a volume of 41.6

cu meter and can hold up to 31.6 tons of dry coal charge. The carbonization takes place at

1000-1050’C in absence of air for 16 -18 hours red hot coke is pushed out of the oven and


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sent to coke. Dry cooling plants where nitrogen gas is used as the cooling medium. The heat

recovery from nitrogen is done by generating steam and expanding into back pressure

turbines to produce 7.5 powers each.

1.3.c Sinter plant(sp):

Sinter is a hard and porous ferrous material obtained by agglomeration of iron ore

fines, coke breeze, limestone fines, metallurgical waste like flue dust, mill scale, LD slag etc.

Sinter is a better-feed material to blast furnace in comparison to iron ore lumps and its usage

in blast furnaces help in increasing productivity, decreasing the coke rate and improving the

quality of hot metal produced. Sintering in two sinter machines of 312 sq.m by heating the

prepared feed on a continuous metallic belt made of pallets at 1200-1300 °C. Hot sinter

discharged from .sintering machine is crushed to 5mm-50mm size and cooled before

dispatching to blast furnace.

1.3.d Blast furnace (BF):

Hot metal is produced in blast furnaces that are tall vertical furnaces and each run

with blast at high pressure and temperature. Raw material such as iron ore lumps/sinter,

fluxes (limestone, dolomite) and coke are charged from the top and hot blast at 1100-1300 °C

and 5.75 KSCG pressure is blown almost from the bottom VSP has two 3200 cu.m blast

furnaces (largest in India) equipped with PAUL WORTH bell-less top equipment with

conveyor charging the two furnace with their circular cast house and 4 tap holes each are

capable of producing 9720 tones of hot metal daily or 3.4 million tones of low sulphur hot

metal annually. Provision exists for granulation of 100% liquid slag and utilization of blast

furnace gas top pressure (115-2atm) to generate 12 mw of power in each furnace by

employing expansion turbines.

1.3.e Steel melting shop (SMS):

Steel is an alloys of iron with; carbon up to 1.8%. Hot metal produced in blast

furnaces contains impurities such as carbon (3.5-4.25%), silicon (0.3-0.4%). Sulphur (0.4%

max) and phosphorus (0.14% max) is not suitable as a common engineering material to

improve the quality that impurities are to eliminated or decreased by oxidation process.

VSP employees three top blown oxygen converts called LD-converters each having 133cum

volume capable of producing three million tones of liquid steel annually 99.5 % of pure

oxygen at 15-16 KSCG pressure is blow in the converter through an oxygen lance having


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convergent-divergent copper nozzles at the blowing end. Oxygen oxidizes the impurities

present in the hot metal that are fixed at slag with basic fluxes such as lime. During the

process heat is generated by exothermic reactions of oxidation of metalloids like Si, Mn, P &

C and temperature raises 1700°C enabling refining and slag formation. This process can

make different grades of steel of superior quality by controlling the oxygen blow or addition

of various Ferro Alloys or special additives, such as FeSi, FeMn, Si-Mn, Coke breeze, Al in

required quantities while liquid steel is being trapped from the converter into a steel ladle.

Converter gas produces as a bi-product is used as secondary fuel.

1.3.f Continuous casting department (CCD):

Continuous casting may be defined as teaming of liquid steel in a mould with a false

bottom through which partially solidified bar is continuously withdrawn at the same rate at

which liquid steel is teamed in the mould. Facilities at a continuous casting machine include a

lift and turntable for ladles, copper mould, oscillating system turn dish, primary and

secondary cooling arrangement to cool the steel bloom. Gas cutting machines is used for

cutting the blooms in required lengths of 6m long. At VSP we have six-4strand continuous

casting machines capable of producing 2.82 million tons per year blooms of size

250X250mm and 250X320mm. The entire quantity of molten steel produced (100%) is

continuously cast in radial bloom casters, which help in energy conservation as well as

production of superior quality products.

1.3.g Rolling Mills:

The blooms produced in SS CCD do not find much applications as such and required

to be shaped into products such as billets, rounds, squares, angles (equal and unequal),

channels, IPE beams, HE beams, wire rods, re-bars by rolling them in 3 sophisticated high

capacity, high speed, fully automated rolling mills, namely light and medium merchant mill

(LMMM), wire rod Mill (WRM) and medium merchants and structural mill (MMSM).

1.3.g.1 Light and medium merchant Mills (LMMM):

LMMM comprises of two units. In the billet/break down mill 250X320 mm size

blooms are rolled into billets of 125X125mm size after heating them in 2 nos. of walking

beam furnaces of 200 tons per hour capacity each. This unit comprises of 7 stands (2

horizontal 850X1200mm) and 5 alternating vertical and horizontal stands

(730X1000mm&630X1000mm). Billets are supplied from this mill to bar mill of LMMM

&WRM. The billets for rolling in bar mill of LMMM are first heated in two-stand roller heart

furnace of 200 tons per hour capacities to temperature of 1150-1200°C. The bat mill


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comprises of 26 stands (8 stands double stand roughing train, 2nos. of 5 stands, double stand

intermediate train and 2 nos. 4 stand single stand finishing trains).

The mill is facilitated with temperature heat treatment technology evaporative cooling system

in walking beam furnaces, automated pilling and bundling facilities, high degree of

automation and computerization.

The mill is designed to produce 710,000 tons per annum of various finished products such as

rounds, rebar’s, squares, flats, angles, and channels besides billets for sale.

1.3.g.2 Wire Rod Mills (WRM):

Wire rod mill is a 4 stand, 25 stands fully automated and sophisticated mill. The bill

has a 4-zone combination type-reheating furnace (walking beam cum walking hearth) of 200

TPH capacities for heating the billets received from billet mill of LMMM to rolling

temperature of 1200oC.

The mill produces rounds in 5.5-12 mm range and re-bars of 8-12 mm range. The mill

is equipped with standard and retarded steel more lines for producing high quality wire rods

and low, medium and high carbon grade meeting the stringent national and international

standards viz. BIS, DIN, JIS, BS etc. and having high ductility, uniform grain size, excellent

surface finish.

1.3.g.3 Medium Merchant and Structural Mills (MMSM):

MMSM is a high capacity continuous mill consisting of 20 stands arranged in three

trains. The feed material to the mill is 250X250 mm size blooms, which is heated to rolling

temperature of 1200°C in two walking beam furnaces each of rounds, squares, flats, angles

(equal and unequal). T bars, Channels, IPE beams/HE beams(universal beams) having high

strength and close tolerances.


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2. MEDIUM MERCHANT & STRUCTURAL MILL

2.1 INTRODUCTION TO M.M.S.M :

Fig 2.1

In Medium Merchant and structural Mills (MMSM) the blooms of size 250X250mm

are heated to temperatures around 1200°C and rolled into different categories of bars

and structural like rounds, squares, flats, angles, channels, HE and IPE beams by

timely estimation of demand.

The mill train of MMSM consists of a total of 20 stands as follows

Roughing train consists of 8 stands as

4 two high horizontal stands.

2 vertical stands,

2 combination stands,

Intermediate train has 6 mill stands as per detail

given below: 2 high horizontal stands,


2 horizontal stands/2 universal stands.

Finishing train consists of 6 stands namely:


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4 horizontal stands/4 universal stands.

2.2 PROCESS DESCRIPTION IN M.M.S.M:

The input material to the mill is continuous cast blooms of size 250x250mm. Two

walking beam type furnaces are provided for reheating the blooms. For charging the furnace,

the blooms are loaded on the bloom charging grids in batches by magnet cranes. Blooms are

visually inspected on the charging grids and weighed one by one on a weigh scale

incorporated in the charging roller table, aligned in front of the furnace and charged into the

walking beam furnace by a bloom charging device. The heated blooms from the furnace are

discharged one by one onto the delivery roller table by bloom discharging device for feeding

them to the first stand of roughing train. During transportation to the first roughing stand, the

blooms are discalced on all 4 sides by a hydraulic declare. The mill train consists of

continuous roughing, intermediate and finishing group of stands. Depending on the section

being rolled the combined stands, provided on each of the continuous trains, are arranged in a

horizontal or vertical position. In case of the rolling of beams suitable number of horizontal

stands, provided in the continuous intermediate and finishing trains are replaced by universal

stands.

Generally, shears installed before the intermediate train and furnishing train cuts the

front ends of the bars. Front end cropping, dividing of finished bars into multiple sale lengths

for cooling bed, emergency cutting and test piece sample cutting is done by the shear

provided after the finishing group. In line size measurement is done for rounds, squares and

flats on equipment provided after finishing group of stands.

Following the shear after the finishing train is a series of water boxes and roller tables

complete with water spraying nozzles for controlled and rapid cooling of divided bars after

which they are directed with the help of a diverter switch to the double sided cooling bed.

The finishing of cooled bars is done on inline automatic finishing lines installed after each

cooling beside. This finishing line is provided with facilities for straightening, cutting,

inspecting, sorting according to surface quality and length, counting, piling, bundling, tying,

weighing and tagging with embossed metallic tags. EOT cranes having 20-ton capacity, 10m

crane rail height and fitted with rotating rolling, spreader beam magnet/slings is available for

removing piled and bundled products to the storage area.


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2.3 MMSM PRODUCTS

Rounds Angles Mc Ismb Flat Blt

40 75*75*8 100*50*5 150 150*10 65*65

45 90*90*6 125*65*5.3 175 150*12 75*75

46.5 90*90*8 150*75*5.7 90*90

48 100*100*8

50 100*100*10

53

56

60

63

65

70

71

80

Table 2.1

Fig no. 2.2


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3. WALKING BEAM REHEATING FURNACE

3.1 IMPORTANT COMPONENTS OF THE FURNACE:

The reheating furnace includes the following components:

Furnace structural framework

Walking beam driving mechanism

Walking beam and fixed beams

Combustion air fan

Burners

Waste gas exhaust system

Refractory and insulation

Fuel system, evaporation cooling system, lubrication and hydraulic system.

The specifications of the blooms being fed into the furnace are:

Blooms _ size

Thickness _ 250mm

Width _ 250mm

Length _ 6000mm

Weight _ 2900kg

3.2 EUIPMENT SPECIFICATIONS:

The walking beam furnace is used for heating blooms of place carbon steel, low

alloy steel, free cutting steel, medium and high carbon steels from ambient to about

100”C. The furnace is charged in two rows foe 6mt long blooms and also with a provision

of charging 12mt blooms. The particulars about the walking beam furnace are as given

below.

Type Top and bottom fixed walking

Beam furnace

Number _ Two

Nominal output charge temperature at _ 250T/hr

Inlet _ Ambient

Discharge temperature at outlet _ 1200’C

Temperature different b/w surface and core _ 30’C


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3.3 FURNACE CONSTRUCTION FEATURES:

The furnace is fabricated from steel plates adequately reinforced with structural steel

member for the robust construction steel plants and steel members of heavy section are

provided to support the hearth.

a) Charging and discharging doors:

The furnace is provided with charging and discharging doors of suitable

dimensions. The doors are fabricated from structural steel sections and lined with

refractory materials. The doors are balanced by counter weights and operated through

electric drives. The discharge doors are of water cooled type. The door openings and

door peripheries are fitted with heat resistant casting.

b) Side doors:

A sufficient number of side doors are arranged over the entire furnace

length at the work load level. Arrangement for manual operation, locking in open

position and wedged guides for ensuring proper tightness in closed position is

provided. These doors and the opening periphery are made of heat resistant casting

with refractory lining, cleanout doors at the furnace hearth level are also provided.

For sealing the gaps at the bottom hearth around walking beam post, water

troughs made out of corrosion resistant steel plates of adequate thickness are

provided.

c) Charging and discharging side front walls:

The charging and discharging side front walls are equipped with water

cooled lintels that support the roof noses.


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3.4 WALKING BEAMS(SKIDS):

Operation:

Blooms are moved forward step by step, avoided any friction or rubbing during

its conveyance through the furnace. The blooms are gently lifted from the stationary

beams, moved forward by walking beams and gently placed on stationary beams. Both

walking and stationary beams are properly supported on vertical posts. The walking

beams supporting posts are fastened to a movable frame which are equipped with rollers

and permit the horizontal movement for the transfer of the blooms. The walking beams

and stationary beams are fabricated out of seamless steam tubes.

Vertical and Horizontal movements:

Vertical and Horizontal movement of the beams are the beams are obtained

through separate hydraulic cylinders. The operation of the cylinders ensures gradual start

up and gradual stoppage during lifting and lowering and horizontal movement.

Charging and discharging equipment:

The blooms are conveyed and positioned in front of the furnace on roller

table by electrical control. After positioning the blooms on the roller table, the blooms are

transferred on the charging table by means of charging device in single row or in two

rows. The blooms are discharging from the furnace separately from each row by means of

discharging device. Two discharging device are suitable for single row or two row

operation.

Hydraulic power station:

A centrally located hydraulic power is provided for the furnace for

operation of the various hydraulic cylinders for walking beam mechanism. The power

unit consists of fluid tanks, pumps with drive and control, necessary solenoid valves, flow

control valves, check valves, pressure relief valves, filters etc. Ore stand by pump with

drive is also provided.

Grease lubrication system:

An automatically controlled centralized lubrication system is provided

with necessary safety arrangement for lubrication of moving parts.


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Skids and support tube cooling system:

Evaporation cooling system (ECS) is provided for cooling of the skids and

support tubes. Steam generated is diverted to plant steam network. The evaporation

cooling system comprises of separating drums, re-circulating pumps, de-mineralized

water, water storage tanks, feed pumps with necessary pipes, valves, fitting, gadgets and

necessary instrumentation. Besides cooling of skids tubes and support tubes by ECS,

following items are also cooled by water.

a. Charge and discharge lintels.

b. Discharge doors.

c. Hydraulic oil.

d. T.V cameras.

3.5 COMBUSTION SYSTEMS:

a) Burner:

Adequate number of burners of suitable design to fire mixed gas in

preheating, heating(top & bottom) and soaking zones are provided. The burners are

provided with peepholes and ignition ports for easy operation and firing. The burner

connected load is 20% higher than fuel consumption rate, which is calculated on the

basis of maximum furnace output.

b) Combustion air fan:

The furnace is provided with two numbers of combustion air fan, one in

operation and one as a standby. The fan is of centrifugal type, directly coupled to air

required for maximum connected load of the burners considering 10% excess of air.

The blowers are equipped with adjustable directional blades on the suction side.

c) Waste gas exhaust system:

i. Chimney : products of combustion are exhausted from the preheating

section of the furnace through underground flue channel leading to

chimney. The height of the chimney is decided considering draft and

statutory regulations. The chimney is of self-supporting type, construction

out of reinforced steel plate and lined with refractory material.

.


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ii. Dampers:

A damper for automatic pressure controlling the waste gas is

made of heat resistant material to withstand the temperature of the waste

gases.

iii. Air and gas recuperators:

Connection type multi-tubular air and gas recuperator is provided in

the waste gas fuel channel. The unit is designed for designed for

preheating the inlet air to the burner manifold to a temperature of around

450’C and a mixed gas leading to the burner manifold to a temperature of

around 380’C. The recuperator tube is made to suitable heat resistant steel

to withstand the high temperature of water gas. Hot air bleed off

arrangement in the duct leading to the burner is provided.

iv. Dilution air fan:

A centrifugal blower complete with accessories is provided for

supplying cold air in the waste gas flue upstream of the recuperator to

prevent the recuperator tubes from overheating.

v. Lagging:

The combustion air pipe and gas pipe and pipe between the

recuperators and the burners is lagged externally with insulating materials

or lines internally with refractory material depending on the diameter. The

lagging is protected by galvanized sheet steel wrapping.

3.6 REFECTERIES AND INSULATINOS :

The roof of the furnace is flat suspended type which is built up with shaped roof

hanged bricks made out of superheat duty fire bricks. The roof hanger bricks are

backed up with a layer of insulating matter. The roof brick hanger is made up of heat

resistant steels

The wall is lined with a high alumina fire bricks up with cold faced insulating bricks

and insulating blocks

The furnace hearth is lined with high alumina fire bricks backed up with cold faced

insulating bricks and insulating blocks


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The doors are lined with high temperature insulating castables. The waste gas flue

upstream of the recuperator is lined with high heat duty fire bricks baked up with cold

faced insulating bricks. Down stream of recuperator is line up with medium heat duty

fire bricks backed up with cold faced insulating bricks. One ventilation course of red

brick is provided between the refractory brick and concrete walls. Thickness of the

refractory layers in the waste gas flue is so chosen that the maximum temperature on

the flue concrete face does not exceed 150’C.

The movable and stationary beams are lined with high alumina castables backed up

by insulation materials.


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4. BASIC HYDRAULICS

4.1 FUNDAMENTALS OF HYDRAULICS:

The word “hydraulics” generally refers to power produced by moving liquids. Modern

hydraulics is defined as the uses of confined liquid to transmit power multiply force, or

produce motion.

Though hydraulic power in the form of water wheels and other simple devices has been in

use for centuries, the principles of hydraulics weren’t formulated into scientific law until the

17th century. It was then that French philosopher Blaise Pascal discovered that liquids cannot

be compressed. He discovered a law which states: Pressure applied on a confined fluid is

transmitted in all directions with equal force on equal areas.

4.2 BASIC HYDRAULIC SYSTEM:

fig 4.1


16

This type of circuit consists of a pump which develops the required pressure, a relief valve,

direction control valve, and cylinder.

The piston in the cylinder either extends or retracts as per the selection of the

directional valve.

a) TANK:

Tank is one of important device to store the large amount of oil Which is used in the

hydraulic system.

b) PUMP:

The function of pump is to convert mechanical energy to hydraulic energy by pushing the

hydraulic fluid into the system.

The hydraulic energy delivered to the system by the pump is in the form of fluid flow.

Thus pump can produce the flow necessary to the development of pressure but a pump can’t

produce pressure since it can’t create or fluid flow resistance on its own.

c) DIRECTION CONTROL VALVES:

Start, stop and direction of flow of a pressure fluid is controlled by means of a directional

control valve and thus the direction of movement or holding positions of a user is determined.

d) FLOW CONTROL VALVES:

The speed of an actuator depends on the rate at which the fluid enters the actuator.

Control of this fluid flow is very important in controlling the speed of the machine parts.

Different types and designs of flow control valves are available depending on maximum flow

rate. Speed of the actuator can be controlled by either controlling the flow rate into it or by

controlling the fluid flow from the actuator.

e) HYDRAULIC CYLINDERS:

Now a day’s almost all earth moving, equipment are provided different types of

hydraulic cylinders. Hydraulic cylinders are devices which produce mechanical output for

pumped for pumps oil into the cylinder chamber.


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4.3 ADVANTAGES OF HYDRAULICS:

Operates at variable speed by varying the pump delivery or using a flow control

valve.

Hydraulic actuators can be reversed instantly while in full motion without damage.

Over load production by means of pressure relief valve.

High power to weight ratio.

Movement from stand still is possible under full load


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5. HYDRAULIC SYSTEM IN REHEATING FURNACE

5.1 INTRODUCTION TO FURNACE HYDRAULICS:

“Walking beam furnace” as the name implies, it is having fixed and moving beams

otherwise known as skids which move from one end of the furnace to the other end with

adjustable stroke length. On these beams, blooms will be charged at the charging end and will

be discharged or extracted from other end as the bloom moves through a fixed distances for

every forward cycle of the system. As the bloom goes from charging end to the discharging

end the blooms becomes red hot to a temperature of 1200c by receiving heat from furnace on

burning CO gas and hot air

Furnace will have two types of beams or skids. One type is called ‘fixed beam’ and

the other type is called ‘moving beam’ or walking beam. Fixed and walking beams are placed

alternatively one besides the other. Walking beam cycle starts lifting the blooms from ‘zero’

position [same level as fixed beams] to upward position for 100mm and moves the bloom

forward for 400mm and goes down keeping the bloom on the fixed beam and still goes down

100mm below the fixed beam level and goes back for about 400mm and comes to original

basic position and moving upward to’ zero’ position. Like this 100 blooms will be charged in

to the furnace for each bloom cycle repeats and moves the bloom towards discharging end

simultaneously heating and soaking of the blooms takes place and finally when the bloom

comes to the discharging end the bloom attains the desired temperature required for rolling.

This bloom is taken out with the help of a bloom extracted and kept on a roller convey or

which feeds the bloom to the mill.

5.1.a FURNACE HYDRAULIC SYSTEM:

This system facilitates the movement of the walking beam such upward, downward

and translator movement. This system also provides a smooth cycle movement without any

rapid or jerk movements so as to avoid any mishandling of the blooms.


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5.1.b HYDRAULIC EQUIPMENT:

Hydraulic equipments consist of the following components:

Complete reservoir, useful capacity of 3000 lit, fitted with heaters, coolers, level and

temperature indicators and temperature controllers.

3 oil conditioning motor pump sets [including 1 as stand by] to continuously filter and

cool the oil contained in the tank.

2 pilot pressure motor-pump sets [including 1 as stand by] one pump is running

permanently. The stand by pump will automatically start in case of any pressure

failures or filter clogging of the running pump.

3 main motor pump sets [life and transfer pump sets] two pumps will be running

permanently one pump the cylinder only. The other feeds in turn the lift cylinders and

the transfer cylinders

1valve/manifold block stand.

The oil delivered by the main pumps and the pilot pressure pump flows through the

stand mounted valves and manifold

Before feeding the lift and transfer cylinder.

Loose manifold blocks and miscellaneous items.


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5.2 SPECIFICATIONS OF FURNACE HYDRAULICS :

a) RESERVOIR:

Fig 5.1

It is mainly used to store the oil that is used in the hydraulic. In this the tank has

storage capacity of 4000lit at a time. And the tank has several valves for the transfer of oil

from different directions.


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Fig 5.2


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S.NO

SPECIFICATIONS

NAME

TYPE

1 1.1 Oil tank with a

total capacity of

4000lit.

Garma

2 1.2.1 Tropicalized

minimum level

switch

(800mm long).

Garma (alarm)


stopping switch

(900mm long).

Garma


stopping switch

(1000mm long).

Garma

5 1.3.1 to 3 Optical indicator. Vcc (vc 3106)

6 1.4.1 to 5 Thermostat and

thermometer.

Ikl

7 1.6.1 to 3 Immersion heater Salva

8 1.7 Air filter. Arofiltre

9 1.8 Drain valve. Sate valve

10 1.10 Hydraulic returns

filter with electrical

indicator.

Hydac

11 1.11 Stop valve Bac

12 1.12 Non-return valve Mg

13 1.13 Non-return valve Mg

14 1.15 Oil cooler Picker

15 1.16 Thermostatic valve Danfoss

16 1.17 Oil cooler

Table 5.1


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b) OIL RECIRCULATION STATION:

Fig 5.3

There are two conditioning motor pump set with the capacity of 150L/min plus one

as stand by.

The oil delivered by the pump goes to the filters stated as 10 microns and through

the cooler.


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Fig 5.4

S.NO SPECIFICATIONS NAME TYPE

1 2.1.1 to 3 Pump Cpl 104

2 2.2.1 to 3 Motor Siemens

3 2.3.1 to 3 Coupling G 338/4p

Coupling

4 2.4.1 to 3 Pump suction

Valve

Dn 40 PN16(40)

5 2.5.1 to 3 Manliness pressure

check connection

686205 type ¼


25

6 2.6.1 to 3 Non return valve SPRC 210 R25M(25)

7 2.7 Ball type gate valve DN 25 PN16(25)

8 2.8 Plug 7050 D3-2k-7055

9 2.9 Pressure gauge 100 E type

10 2.10 Isolating valve RPA2.3.3.CL(6)

11 2.11 Ball type gate valve DN 50 PN16(50)

12 2.12.1 to 2 Non-return valve SPRC 410 F50M

13 2.13 Pressure relief

valve

DS DC 212 F50

14 2.14 Hydraulic return

line filter

VR2/D/1/24

15 2.18 Motor pump Base frame

16 2.20.1 to 3 Suction flexible

connection

DN 40 PN16(40)

17 2.21 Tank filling pump MPG2/1/0/M/0.75klo/415

Table 5.2

b) PILOT STATION:

Fig 5.5


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There are two pilot pressure pumps, including one as stand by with the unit capacity

of 18 L/min.

Each pump is equipped with one filter, mesh size 5 microns and one electrical

clogging indicator. There is a single pressure relief valve for relieving the oil of more than

80bar.

Fig 5.6


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S.NO

SPECIFICATIONS NAME TYPE

1 3.27.1 to 2 Pilot pump suction

flexible connection

DN 20 B type (20)

2 3.4.1 to 2 Pilot pump suction

valve

DN 20 PN16

3 3.1.1 to 2 Pilot pump CPL 13S

4 3.3.1 to 2 Pilot pump motor

coupling

GE 282 coupling

5 3.5.1 to 3 Pressure switches B2T 1132-SS-F3

6 3.6.1 to 3 Shut valve RPA 2.3.2.CL(6)

7 3.7.1 to 4 Non-return valve SPRC 210 R15M

(12)

8 3.8.1 to 2 Hydraulic filter

with electric

contact

DFBN 60

G5D1/L48

9 3.9 Pressure gauge 0-100bar, E type

10 3.10 Isolating valve SPM 101 1(1/4)

11 3.11 Pressure relief

valve

DVDA 202

12 3.12 Chock valve VRF 40 (1/2)

13 3.13 Accumulator with a

capacity of 10lit

IHVIO 250

14 3.14 Accumulator DI 16 MS

15 3.17 Non-return valve SPRC 210 R15M

(10)

16 1.18.1 to 2 Two position DC

valve with 48V DC

2204835 (7)

17 3.19.1 to 2 Pressure relief

valve

ZUDAIAT 2Z07B

18 3.20 Diaphragm 1.5

19 3.22 Pr. Relief valve DVD 212 E15B

Table 5.3


28

c) MAIN-PUMP STATION:

Fig 5.7

There are two motor pump sets plus one as standby operating either as semi open

circuit or in closed circuit.

One pump exclusively used for lifting.

The other pump is used for lifting and transfer.

The stand by pump may replace either pump via a set of manual valves.

Each set includes one pump of axial piston and variable displacement type, fed by a

boost pump coupling to the main pump.


29

Fig 5.8


1 4.1.1 to 3 Pump 2VPN0226/AKOO

2 4.2.1 to 3 Motor LA2 206

3 4.3.1 to 3 Coupling 90 KW/VP

4 4.4.1 to 3 Suction valve DN 50 PN16


valve

2217289 (24)

6 4.6.1 to 8 Delivery valve DN 40 PN250(40)

7 4.7.1 to 3 Pilot valve DN 15 PN250(15)

8 4.8.1 to 3 Drain line non-

return valve

SPRC 210

R25M(25)

9 4.9.1 to 6 Manliness pressure

check connection

686205 “1/4”

10 4.10.1 to 6 Non-return valve 2217487-B

11 4.11.1 to 6 NRV for pump

station

2.10.8718-(1 ½)


30

12 4.12.1 to 3 DC valve W43MC06CI PO7

ZBF

13 4.15.1 to 4 DC valve W43MC03M5

PO7 ZBF

14 4.16.1 to 10 Flow control valve ZRHA 3EE 2Z07

15 4.17.1 to 3 Boosting pump CPL 138S

16 4.18.1 to 3 Pump side valves

(drain valve)

DN 15 PN 250

17 4.19.1 to 3 Suction valve DN 50 PN16 (50)

18 4.20.1 to 6 Non return valve SPZ5E10 (10)

19 4.21.1 to 3 Security valve DSDA 212 R25B

20 4.22.1 to 3 Drain line hose SAE 100R2

21 4.23.1 to 3 Pump side valves SAE 100 R2 3/8

22 4.24.1 to 3 Pilot line hose SAE 100 R2 3/8

23 4.25.1 to 8 Delivery hose SAE 100 R10

Table 5.4

d) LIFT & TRANSFER MANIFOLD BLOCK:

Fig 5.9


31

The oil coming from the lift pumps arrives at P3 and P4. The oil entering P1 and P2

comes out of C% and C6 towards the lift cylinder, where as the oil entering P3 and P4

alternatively comes at C5 and C6 towards the lift cylinder or at C7 and C8 towards the

transfer cylinder.

The fluids directed by means of two directional valves pilot controlled by the

solenoid valve 5.2. The following components are also mounted on the same manifold block.

One solenoid operated valve to pilot control the non return valve mounted on the lift

cylinder.

One pressure relief valve set at 25 bar approximately

One pressure switch.

Fig 5.10


32


1 5.1 Manifold block 1.23.11441

2 5.2 S3/S4 valve W42MCO 3MS

PO7ZBF

3 5.3.1 to 2 DC valve 2179411 (25)

4 5.4 DC valve W42MC 22BI PO7

ZBF


valve

221.7020 (25)

6 5.6 Pr. relief valve 221.7020 (25)

7 5.7 Non-return valve 2217487B

8 5.8 Block to drain

valve

DN15 PN250(15)

9 5.9 Non-return valve 2217487B (25)

10 5.10 Pressure switch B2TM48SS-F3

11 5.11 Isolating valve RPA.2.3.2.CL(6)

12 5.12.1 to 4 Minim’s 686205 ¼

13 5.15.1 to 4 Isolating valves DN 32 PN250

14 5.16 Flow control

double valve

ZRHA IFF Z07(7)

15 5.17 Manifold block at

transfer cylinder

1.23.11492

Table 5.5

5.3 WORKING OF EXISTING HYDRAUIC SYSTEM

UPWARD HALF MOVEMENT OF WALKING BEAMS:

1. (Position 0 to Position 1):

In this two pumps are utilized (4.1.1 and 4.1.2).

Order to start (given by the PLC).

Energization of solenoid S3(valve 5.2): lift cylinder are then fed by

pump.


33

Energization of solenoid S1.1, S2.1, S1.2 &S2.2, pressure is then

applied.

Energization of solenoid S12.1, S12.2 & S12.3: pilot pressure is then

equal to 27 bar.

Energization of solenoid S8.1 & S10.1 and energization of solenoids

S5.1: pilot pressure of 27 bars is obtained at port C20 of the pump

positioned.

This positioned actuates the mechanical servo valve which controls the pump swash

plate, actuator cylinder.

The swash plate is then F position (forward) and then flow delivered through port C1

will achieve the upward movement through the lift cylinder.

FORWARD MOVEMENT OF WALKING BEAMS:


In this one pump is utilized (4.1.1)

Order to start (given by the PLC).

Energization of solenoids S1.1 & S2.1. If they are no longer energized

pressure is then applied to the pump.

Energization of solenoids S4 transfer cylinder is then fed by pump.

Energization of solenoids S12.1 and S12.3 pilot pressure is then equal to

20 bars.

Energization of solenoids S7.1 pilot pressure of 20 bars is then obtained

at port C20 of the pump positioned.

This positioned actuates the mechanical servo valve which controls the swash plate actuator

cylinder. The swash plate is then in F position (forward) achieves the forward movement

through the transfer cylinder.

DOWNWARD MOVEMENT OF WALKING BEAMS:


In this two pumps are utilized (4.1.1 &4.1.2).

Order to start (given by PLC).

Energization of solenoids S1.1, S2.1, S1.2 &S2.2. If they are no longer

energized pressure is then applied to the pumps.

Energization of solenoids S12.2 and S12.3 pilot pressure is then equal to

13 bars.


34

Energization of solenoids S8.1 & S10.1 and energization of solenoids S5.1.

Pilot pressure of 13 bar is obtained then at port C20 of the positioned.

Start of a time delay of 1.75 seconds.

The positioned actuates the mechanical servo valve which controls the swash plate actuator

cylinder. The swash plate s then in F position (forward) and the flow delivered through port

C1 will achieve upward movement and the downward movement through the lift cylinder.

BACKWARD MOVEMENT OF WALKING BEAMS:


In this one pump is utilized (4.1.1).

Order to start (given in PLC).

Energization of solenoids S1.1, S2.1, if they are no longer energized, pressure

is then applied to the pumps.

Energization of solenoids S12.1 & S12.3: pilot pressure is then equal to 20

bars.

Energization of solenoids S7.1 & S9.1 &S6.19: pilot pressure of 20 bars is

then obtained at port C2 of pump positioned.

This positioner actuates the mechanical servo-value which controls swash plate actuator

cylinder. The swash plate is then in “R” position (reverse) and the flow delivered through

port C2 will achieve the backward movement through the cylinder transfer cylinder.

DOWNWARD HALF MOVEMENT OF WALKING BEAMS:

5. (Position 1 TO Position 0):

This movement is performed then the IDLE mode is interrupted with the walking

beams in up position (Position 1).

This movement is the same as the one described in above point i.e. downward

movement of walking beams (Position 2 to Position 3).

FULL UPWARD MOVEMENT OF WALKING BEAMS:


This movement is performed when cycles of walking beams come one after the other

without any interruption.


35

5.4 MERITS AND DEMERITS OF EXISTING FURNACE HYDRAULIC

SYSTEM:

5.4.a MERITS:

Proven system from long years.

Smooth control of the cycle is possible.

This system is immunes to all safety controls.

Frequent adjustments not required.

System is robust and durable.

5.4.b DEMERITS:

More interruption and higher down time.

System is proven but due to obsolescence of spares is problem.

Advancements of the pump control superseding is problem.

Debugging in the commissioning stage is quite time taking.

Requires continuous monitoring of the system.

Chance of catastrophic any mal operation.

Spares cost is high compared to new system.

Difficult to understand by all people and at requires theoretical and practical

knowledge about the system.

Servo related problem occurring due to the cleanliness of the oil.


36

6. MODIFICATION OF FURNACE HYDRAULIC SYSTEM

6.1 NEED OF MODIFICATION:

In the event of occurrence of a repeat problem the solution is available in case of a

one-off problem it becomes laborious as there are numerous check points.

Due to technological obsolescence and the high rate of up gradation the availability of

spares and its associated techno economics influence the running of the system.

In such cases sustaining an old system economically is not feasible and up gradation to an

updated system is not a matter of choice hut a matter of compulsion.

6.2 BASIC THINGS IN MODIFIED HYDRAULIC SYSTEM:

a) Servo valve:

An electro hydraulic servo valve is a device that takes an electrical current and

turns it into hydraulic flow which can then create linear, rotational, uni-directional or

reciprocating mechanical motion. Servo valves were invented during the late 1940’sfor

military use. In the 1960’s MTS Systems Corporation began using servo valves in

displacement and force controlled test equipment. There are several types of servo valves,

including the flapper nozzle style 4-way valve.

Servo valve

Fig 6.1


37

Servo valve parts:

Fig 6.2

fig 6.3


38

b) Proportional valve:

An electrical input from some source is wired to an amplifier card which in turn,

controls a coil on the proportional valve. Since the electrical input from most sources

is generally much lower in power than the amount of current required to operate the

coil, the input current must be amplified. This function is fulfilled by an amplifier

card. The amplifier may be mounted on the valve, sometimes termed OBE (on board

electronics) or be remote from the valve. The source of the input may come from

several devices, including a potentiometer controlled by the machine operator, from

preset potentiometers, a joystick, or from a PLC.

Fig 6.4

The amplifier card drives the valve coil with a current signal. As the current flows through

the coil, electromotive force is developed, causing the armature of the solenoid assembly to

move. The armature, in turn, inputs force to the valve spool, in a flow control, pressure

reducing, or directional control valve, or the poppet in a pressure relief valve. The spool or

poppet is offset by a

spring. Therefore, the force input by the solenoid assembly is opposed by the force

6.3 COMPARISION BETWEEN PROPORTIONAL & SERVO VALVES:

Proportional Valve Servo valve

- Open loop control - Close loop control

- less costly than servo valves - very expensive

- require more power (50W) - low power input (.1 - .3W)

- moderate filtration (30 m) -high filtration (1-5 m)

- spools are overlapped - spools critically lapped

- flow-current characteristics -flow-current characteristics

very nonlinear linear

- hysteresis large 0.5% - very low hysteresis 0.1%

- can be used as flow, pressure and - used primarily in closed loop to


39

Directional control valves (pressure creates flow and pressure control

Compensation)

- can be used in closed loop control if - when used in closed loop, high

Expectations not high - performance is expected

In general proportional valves find most of their applications in open loops situations

where pressure and flow are required to change continuously, where multiple fixed flow and

pressure valves can be replaced by a single valve and where acceleration and deceleration

under control are required.

6.4 WORKING OF MODIFIED HYDRAULIC SYSTEM:

UPWARD HALF MOVEMENT OF WALKING BEAM:


Two pumps are utilized (4.1.1 & 4.1.2)

Order to start (given by PLC)

Energization of solenoid S3: lift cylinder are then fed by pump 4.1.1.

Energization of solenoids S1.1, S1.1, S2.1.

Description is given with reference to the walking beam movement as given in the

walking beam cycle.

PLC output Q156, R5 and R7 activates the amplifier cards to apply command

voltage P.X.1 to the proportional valve of main pump. This results in the pump

swash plate movement in forward direction to an angle proportional to the

command voltage. Walking beam starts upward movement through lift

cylinder.

Flow is released to the pipe at the rear end of the cylinder. The non return

valve 6.2.1 and 6.2.2 open without external action. The oil trapped at front end

of the cylinders flows back towards the pump. However, since the amount in

the rear end is greater than at front end, the different is sucked by the pumps

from the boost lines. Each cylinder reaches the limit switch at slow control

position.

Now PLC output W156 will go in OFF condition and Q158 will go in ON

condition. This results to activate amplified cards such that command voltage

P.X.3 applied to the proportional valve of main pumps. The swash plate


40

moves towards zero degree to an angle proportional to command voltage

P.X.3.

Each cylinder reaches the limit switch at stop control position.

PLC output R5, R7 goes to OFF condition which results in the application of

zero command voltage to the proportional valve of main pumps. This positions

the swash plate at zero angle position. At same time PLC output Q159 activate

the amplified cards to apply command voltage P.X.4 with not change the

swash plate position till the PLC outputs R5, R7, R9, R6, R8 and R10 are in

OFF condition.

FORWARD MOVEMENT OF WALKING BEAMS:


One pump is utilized (4.1.1)


Energization of solenoids S1.1 & S2.2 Z

Energization of solenoid S4. Transfer cylinder is then fed by the pump.

The PLC output Q157 & R5 activates the amplifier cards to apply command

voltage P.X.2 (equivalent to 20 bar in existing system) with ramp R.X.@ to

the proportional value of main pump. This results positioning of swash plate

“F” position to the angle proportional to the command voltage P.X.2. Walking

beam starts forward movement through transfer cylinder.

The cylinder being of the double rod type, there is as much oil entering the

cylinder (inlet end) as oil coming out from the outlet end. Therefore pump

does not require any make up oil except for compensating leaks. The cylinder

reaches the limit switch at slow down control position.

PLC output Q157 goes in OFF condition and at same time PLC output Q 159

goes ON condition. This activates the amplifier cards to apply command

voltage P.X.4 with ramp R.X.4 to the proportional valve of main pump. Swash

plate moves towards angle zero degree to an angle proportional to the

command 4.

The cylinder reaches the limit switch at Stop control position.

PLC output R5 goes to OFF condition with results in the application of zero

command voltage to the proportional valve of main pump. The swash plate

goes to zero degree angle position. However PLC output Q 159 will remain

ON but this will not change the swash plate position till the PLC output R5,

R7, R9, R8 and R10 are on OFF condition.


41

Each cylinder reaches the limited switch at stop position. Reaches the limit

switches located at the cylinder stop position authorizes initiation to the next

movement. De-energisation of solenoid S4 and energization of solenoid S3.

Lift cylinders are then fed by pump 4.1.1. This is normal “stand by “position

which is also utilized between two cycles.

DOWNWARD MOVEMENT OF WALKING BEAMS:


Two pumps are utilized (Items 4.1.1 & 4.1.2)


Eneregization of solenoids S1.1, S2.1, S1.2 & S2.2

Pressure is then applied to the pumps.

PLC output R5 and Q158 activates the amplifier cards to apply command voltage

P.X.3 with rampR.X.3 to the proportional valve of the main pump. Counting time

delay of 1.75 second approx. Starts. This results in the swash plate movement to

achieve upward movement of walking beam through lift cylinder.

Flow is released to the pipe line the rear end of the cylinder. The non-return valve

6.2.1 and 6.2.2 open without external signal. The oil trapped at front end is greater

than at front end, the difference is sucked by the pumps from the boost lines. At half

time of the delay, Energisation of solenoid S1: pilot control check valves of lift

cylinders are maintained in the open position. End of the time delay.

PLC output R5 & A158 goes to OFF condition and at the same time PLC output R6 &

R8 & Q156 becomes one. This activates the amplifier card such that a command

voltage P.X.1 with ramp R.X.1. Applies to the proportional valve of main pump. The

swash plate which was in F position goes through an angle zero. Degree to reach a

reverse angle proportional to the command voltage P.X.1. Pump gives flow in reverse

direction to achieve downward movement of walking beam through lift cylinder.

Each cylinder reaches the limit switch at slow down control position.

Now PLC output Q156 will go in On condition. This result to activate amplifier cards

such that command voltage P.X.3 applied to the proportional valve of main pumps.

The swash plate moves towards angle zero degree to an angle proportional to

command voltage P.X.3.

PLC output R6, R8 goes to OFF condition which results in application of zero

command voltage to proportional valve main pumps. This positions the swash plate at

zero angle position. At same time PLC output Q159 activate the amplifier cards to

apply command voltage P.X.4 with ramp R.X.4 to proportional valve of main pump.


42

But this will not change the swash plate position till the PLC outputs R5, R7, R9, R6,

R8 and R10 are in OFF condition. Each cylinder reaches the limit switch at stop

position. Reaching the limit switches located at the cylinders stop position authorizes

initiation of the next movement.

BACKWARD MOVEMENT OF WALKING BEAM:


One pump is utilized (Item 4.1.1)

Order to start (given in PLC)

Energization of solenoids S1.1, S2.1 and de-energization S1.2 & S2.2 then pressure is applied

to the pump. Energization of solenoid S4: Transfer cylinder is then fed by pump 4.1.1.

The PLC output Q157 & R6 activate the amplifier cards to apply command voltage

P.X.2 to the proportional valve of main pump. This results positioning of swash plate

to an angle proportional to the command voltage P.X.2. Walking beam starts

backward movement through transfer cylinders.

The cylinder being of the double rod type, there is as much oil entering the cylinder as

oil coming out from outlet end. Therefore pump does not require any make-up oil

except for compensating leaks. The cylinder reaches the limit switch at slow down

control position.

PLC output Q157 goes in OFF condition and at same time PLC output Q159 goes in

ON condition. This activates the amplifier cards to apply command voltage P.X.4

with ramp R.X.4 to the proportional valve of main pump. Swash plate moves towards

angle zero degree to an angle proportional to the command voltage P.X.4.

The cylinder reaches the limit switch at stop control position.

PLC output R6 goes in OFF condition which results in the application of zero degree

angle position. However PLC output Q159 will remain ON but this will not change

the swash plate position till the PLC outputs R5, R6, R9, R8, and R10 are in OFF

condition. De-energization of solenoid S3 lift cylinders are than fed by pump 4.1.1.

This is the normal “stand-by” position which is also utilized between two cycles.

UPWARD HALF MOVEMENT OF WALKING BEAM:


Same movement as the one described in upward half movement of walking beams.


43

DOWNWARD HALF MOVEMENT OF WALKING BEAM:


This movement is performed when idle mode is interrupted with the walking beam

in up position.

The following hydraulic solenoid valves will be removed from the existing system.

FULL UPWARD MOVEMENT OF WALKING BEAM:


This movement is performed when cycle of walking beam come one after the other

without any interruption.

Same movement as the one described in upward half movement of walking beams.

There is no change in scheme of selecting two pumps for running from the three

pumps available. Hence there will not be any change in the operation of walking

beam cycle with the selection of other combination

of pumps.

6.5 MERITS AND DEMERITS OF MODIFIED HYDRAULIC

SYSTEM:

MERITS:

Minimum down time (no pump related problems).

Minimum availability of the system.

Improvement in TEF (Techno economic factors).

Cost of installation of the project is less (old system main pump cost is equal

to the total project of the new system).

Less system problems due to few manual controls.

Less human involvement due to more user friendly PLC.

Low temperature raise in the system.

Less leakages of oil at pump area.

Less sound and smooth in operation


44

DEMERITS:

More chances of double booster pump failures in the main pump.

More vibration in pilot station causes pipe failures.

Main pump drain hose failures due to improper pressure rated hoses.

Aversion of the people due improper knowledge of the system.

Chances of miscommunication between electrical and mechanical for fine

tuning of the system due to PLC.


45

7. CONCLUSION

7.1 CONCLUSION ABOUT EXISTING FURNACE HYDRAULIC

SYSTEM:

The present hydraulic system in terms of performance and reliability is more than

satisfactory. In the event of occurrence of a repeat problem the solution is available in case of

a one-off problem it becomes laborious as there are numerous check points compared to the

modern hydraulic system.

Due to technological obsolescence and the high rate of up gradation the availability of

spares and its associated techno economics influence the running of the system. In such cases

sustaining an old system economically is not feasible and up gradation to an updated system

is not a matter of choice hut a matter of compulsion.

Due to more human involvement with manual adjustments failures of a higher order are

possible and closer monitoring of the system is required.


46

7.2 CONCLUSION ABOUT MODIFIED FURNACE HYDRAULIC

SYSTEM:

The success or failure of a new system depends on various factors such as availability,

reliability, maintainability etc. in addition to the above, techno economics plays a very vital

role in the success of an implement system.

The main benefits derived from the implementation of new system are:

Reduction of delays by 90% compared to previous system.

Ready availability of spares.

Cost competitive with respect to cost of new system versus sustainability of the old

system.

Improved system performance due to lower system oil temperature.

Keys human interference due to incorporation of PLC.

Indigenization as a substitute to imported spares.

System is less cumbersome with lesser number of valves & associated controls.


47

7.3 RECOMMENDATIONS FOR MODIFIED HYDRAULIC

SYSTEM:

After modification, we found some more alterations in the modified system to be done

in future for the improvement of the system. The alterations are listed below,

In corporation of superior oil refining systems like centrifuge, ELC’s etc.

Provision of flexible hoses in the discharge line of pilot pumps in order to minimize

the impact of vibration or provision of vibration isolator pads for pump & motor base.

Provision of flexible hoses in the suction line of pilot pumps to avoid air entry In to

the pump (by this we can eliminate rubber compensator).

Replacement of higher rating hoses in place of existing hoses.

Simplification of design by replacing the double booster pump with a single booster

pump. so as to eliminates repetitive coupling failures.

Fine tuning of the PLC to smoothen the forward/backward movement of the cycle.

Finally for the successful running of any hydraulic system the various parameters

like temperature of the system, quality of oil with respect to NAS etc should be maintained in

certain limits.


48

8. BIBLOGRAPHY

Project report of study of hydraulic system (2008-2009).

Fluid Mechanic’s and Hydraulic Machinery by R.K.JAIN.

Oil Gear Tower literature.

Rexroth literature.

T&DC Hydraulic Manual of VSP.

Other details from MMSM planning.


49

9. ANNEXURE

HYDRAULIC SYMBLOS

Lines

-continuous line - flow line

-dashed line - pilot, drain

-Envelope - long and short dashes around two or more

component symbols.

Circular

-large circle - pump, motor

-small circle - Measuring devices

-semi-circle - rotary actuator

Square

-one square - pressure control function

-two or three adjacent squares - directional control

Diamond

-diamond - Fluid conditioner (filter, separator,

lubricator, heat exchanger)

Miscellaneous Symbols

-Spring

-Flow Restriction

Triangle

-solid - Direction of Hydraulic Fluid Flow

-open - Direction of Pneumatic flow

Pumps and

Compressors

Fixed Displacement hydraulic pump

-unidirectional

-bidirectional


50

Variable displacement hydraulic pump

-unidirectional

-bidirectional

Compressor

Motors

Fixed displacement hydraulic motor

-unidirectional

-bidirectional

Variable displacement hydraulic motor

-unidirectional

-bidirectional

Pneumatic motor

-unidirectional

-bidirectional

Rotary Actuator

- hydraulic

- pneumatic

Cylinders

Single acting cylinder

-returned by external force

-returned by spring or extended by spring force

Double acting cylinders

-single piston rod (fluid required to extend and

retract)

-double ended piston rod

Cylinders with cushions

- single fixed cushion


51

- double fixed cushion

- single adjustable cushion

- double adjustable cushion

Directional Control Valves

Directional control valve (2 ports / 2 positions)

-Normally closed directional control valve with 2

ports and 2 finite positions.

-Normally open directional control valve with 2 ports

and 2 finite positions.


-Normally closed directional control valve with 3

ports and 2 finite positions.

-Normally open directional control valve with 3 ports

and 2 finite positions.


-directional control valve with 4 ports and 2 finite

positions



positions

*-(center position can have various flow paths)

Directional control valve (5 ports / 2 positions) Normally a pneumatic valve


positions

Directional control valve (5 ports / 3 positions) Normally a pneumatic valve


positions

Proportional directional control valve

Electro-hydraulic servo valve

-The spool positions on these valves is variable allowing for variable flow

conditions.

-single-stage direct operation unit which accepts an

analog signal and provides a similar analog fluid

power output

-two-stage with mechanical feedback indirect pilot

operation unit which accepts an analog signal and

provides a similar analog fluid power output

Control Methods


52

Manual Control

-general symbol (without showing the control type)

-pushbutton

-lever

-foot pedal

Mechanical Control

-plunger or tracer

-spring

-roller

-roller(one direction only)

Electrical Control

-Solenoid (the one winding)

Pilot Operation

-pneumatic

-hydraulic

Pilot operated two-stage valve

-Pneumatic: Sol first stage

-Pneumatic: Air pilot second stage

-Hydraulic: Sol first stage

-Hydraulic: Hyd pilot second stage

Check valves, Shuttle valves, Rapid Exhaust valves

-check valve -free flow one direction, blocked flow

in other direction

-pilot operated check valve, pilot to close

-pilot operated check valve, pilot to open

Shuttle valve

-to isolate one part of a system from an alternate part

of circuit.


53

Rapid exhaust valve/Pneumatic

-installed close to an actuator for rapid movement of

the actuator.

Pressure Control Valves

Pressure Relief Valve(safety valve) normally closed

- line pressure is limited to the setting of the valve,

secondary part is directed to tank.

Proportional Pressure Relief

- line pressure is limited to and proportional to an

electronic signal

Sequence Valve

- when the line pressure reaches the setting of the

valve, valve opens permitting flow to the secondary

port. The pilot must be externally drained to tank.

Pressure Reducing valve - pressure downstream of valve is limited to the

setting of the valve

Flow Control Valves

Throttle valve

-adjustable output flow

Flow Control valve

-with fixed output (variations in inlet pressure do not

affect rate of flow)

-with fixed output and relief port to reservoir with

relief for excess flow (variations in inlet pressure do

not affect rate of flow)

-with variable output

-fixed orifice

-metered flow toward right free flow to left

-pressure compensated flow control fixed output

flow regardless of load

-pressure and temperature compensated

-with variable output and relief port to reservoir

Flow dividing valve


54

-flow is divided equally to two outputs.

Shut-Off Valve

-Simplified symbol

Filters, Water Traps, Lubricators and Miscellaneous Apparatus

Filter or Strainer

-manual drain

Water Trap

-with manual drain

-with automatic drained

Filter with water trap

-with manual drain

-automatic drain

Air Dryer

refrigerant, or chemical removal of water from

compressed air line

Lubricator

-oil vapor is inducted into air line

hydraulics in vizag steel plant

Documents