design phylosiphy power intake .final - copy

8/2/2019 Design Phylosiphy Power Intake .Final - Copy

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Name of work: - Kashang (243MW) HEPName of Component: - Heating arrangementTitle of drawing: - Second stage embedments and gate leaf (emergency

gate,shingle flushing & regulator gates)

Design Philosophy:-

1. Preamble:-

Exposed mechanically operated systems of the gates may be frozen-in winters and become

inoperable .The weight of ice on the structures that need to be moved may become excessive so

that the lift system overloaded .Ice Load can also cause structural damage .Therefore the need of

de icing of the gates arises

The major concern in winters is that icing may jam the gate leaf and hoisting may become in

operable, to forgo this problem heating of embedments and gate leaf is required. Heat has been

used for the years at hydraulic structures to control the icing .Typical methods includes steam

lances, heat embedded in concrete walls , mineral insulated heaters installed under steel side-seal

rub plates. Though these have proven effective ,they all have demonstrated limitations . Steam

lances pose the same problems as pike poles and other manual methods in that they are very labor

intensive and slow ,and they frequently require the placement personnel .The practice of

embedding heat tracing in the concrete provides only short term benefit , as the heaters burn out

after relatively short service and can not easily be replaced. ForKashang we have proposed the

system in which the heaters are easily replaceable for maintenance.

2. Materials:

S.No Component / Part Recommended Reference

1 Heat transfer fluid Ethylene glycol EM-1110-2-1612

2 Heater Coil ---------- catalog

3. Permissible temperature in contact with gate and ice sheet shall be 0.5C or above so that the

ice melts keeping the gate unjammed .

4. Design Data:

A. Gate

i)Type of heating arrangement. Heating coil in pipe filled withethylene glycol


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Ice Load:

As the ice load which is the additional load on structure of the gate it needs to be

incorporated for the structural analysis of the gate leaf so as to protect it from the

structural damage. IS-4622 clause-8.1 a gives various ice loading conditions for the

structural analysis of the gate.

5. Detail Design Consideration :

5.1 Heater Design

Sizing of heater is most important part in the design of heating coil.

Embedment Heater

1.The Heat loss from a heating panel mounted in embedments is the combination of the

convective heat transfer to the air and conductive heat transfer into the wall.The heater has

to provide enough power to maintain the temperature of the surface above freezing despite

these heat losses . The power requirements of the heaters are simply the sum of mentioned

losses.

Gate Heaters

1.In gates heat transfer for many situations where ice forms on the skin plate is classified in

two cases

a) Water on one side air on the other.

b) Similar fluid on both sides.In both of these cases only the situation where the gate is closed is considered .The reason

for this is that the heat losses associated with water flowing over heated surface are so large

that operational costs associated with keeping the surface ice-free prohibitive.Thus the

standard operating procedures for the heaters and gates should be taken into account that

heaters will be ineffective when the gates are open.Heat loss calculation similar to the

embedments are done to calculate the power requirement heat up the gate to a minimum

temperature of 0.5C .Once an estimate of heat loss at the gate is determined ,the spacing

and number of the heater elements has to determined by treating skin plate as a fin with a

point source of heat spaced at regular intervals across the plate.The spacing of the heat

sources needs to be close enough so that the dip in temperature between sources stays

above 0.5C.


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6. ConclusionIn heater design calculations for embedments of Kashang HEP total heat loss was

calculated as per Engineering manual .Two cases were analyzed with air as medium for heat

transfer and ethylene glycol as other medium for heat transfer. It was concluded that two

heaters each of 3.2mm dia and wattage of 2.5 KW on either side would be sufficient for de

icing in embedments .Similarly heat loss for the gate leaf is calculated with ethylene glycol

as heat transfer medium.For determining the total heat loss ,size of heater and number ofheaters required to keep a minimum temperature of 0.5C on the gate leaf number of

iterations are done .It was concluded that two heaters in six rows on the gate leaf of 1919

watts would help in de icing of the gate leaf and would prevent gate from jamming.

7. References:

y IS 4622 (2003): Recommendation for structural Design of Fixed Wheel Gate

y EM-1110-2-1612 :Chapter 20 Control of icing on Hydraulic structures.

Designed by

PESPL.

Checked by

Er. DheerajrThakur

Submitted by

Er. Davinder Choudhary

Recommended by

Er. Naveen . K. kaushal

Approved by

Er. P.K.Kohli

design phylosiphy power intake .final - copy

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