how to cal C.v for melting Lead

I have a Lead melting pot here, if you want it, you pay for the shipping and packing.

The material holder is about 2 foot diameter and about 1.5 foot deep, with 2 Large electric heater elements.

weights more than 500kgs, could be 1T, dunno, takes a bit to move it around ;o(

Quantity of heat reqd = m.s.delta T. Where m= mass in kg, s= specific heat capacity of lead in kcal/kg-deg C and delta T=melting temp(t1)-ambient temp(t2) in deg C. This gives you the heat in kcal reqd to raise the temp to desired level t1, in ur case 375. Then you have to add up heat required in the form of latent heat to melt the lead into liquid (kcal/kg can be found from material specs). The sum gives total heat reqd to melt. You then add up the radiation losses from the pot/furnace (to be assessed by you based on the furnace design or u can get data from the OEM) for 1 hr. This is to be added up to get total heat reqd in kcal. Say LPG is used for this application. LPG has a CV of 10,800 kcal/kg. You then have the answer as 10800/heat reqd (kg of lpg per kg of lead melting).

Specific latent heat of fusion (/melting) of lead is 22.4KJ/Kg from:-

http://www.engineeringtoolbox.com/latent-heat-melting-solids-d_96.html

check somewhere else though

Specific heat capacity of lead is 130 J/(Kg°C) from

http://www.standnes.no/chemix/periodictable/specific-heat-capacity.htm

I don't know anything about chemistry, but, this piece of software (chemix) looks really good.

I have designed a lead pot to melt 4kg/min at 360'C with 6KW. It is possible to use LPG intead of Electric heater. My appication is also casting. Will this information helps you?

Dear Rajkumar

I am Nagesh from Bangalore my cont no 98864 90195

Pl inform me what is the quantity(KG) of lead. The general practice is lead will be malted to 425C for casting.

Since quantity of lead is not mentioned, let us assume it as 100 kgs.

Sp. heat of both solid & liquid lead = 0.032.

Melting point of lead = 327 deg. C

Latent heat of fusion = 5.5 kcal/kg.

Pouring temp. assumed = 450 deg. C

Delta T = 450 - 25 = 425 deg. C

Heat reqd. to melt 100 kgs. of lead & raise to 450 deg. C in 1 hr.

= 100 x 0.032 x 425 + 5.5 x 100 = 1910 Kcal/hr.

System efficiency depends on various factors, like type of insulation (insulation brick + fire brick or ceramic fibre), whether lid is provided or not, exhaust opening etc. It varies from 30% to 65%. Assuming 50% efficiency,

Heat reqd. = 1910/0.5 = 3820 kcal/hr.

GCV of LPG = 11800 kcal/kg.

combustion efficiency assumed = 0.9

NCV of LPG= 11800 x 0.9 = 10620 kcal/kg.

LPG consumption = 3820/10620 = 0.36 kg.

So, you have to choose an automatic LPG burner of capacity, 0.25 to 2.5 kgs./hr. (Generally, turn down ratio will be about 10) You can select any imported burner for this.

You have also to provide an automatic temp. controller to get a closer temp. control accuracy, better product and improve efficiency.

Dear Mr Mahadevan,

Thank you very much for your infromation.

Regards

M.Rajkumar

Dear Rajkumar,

Why you are Intrested in using Lpg. If you are in continous process you can
go for LDo which is Three times cheaper than Lpg.Lead Melting point 375 deg c .But to sustain in molten stage and to flow it has to go upto 425degreecelcius.
If you allow it to flow slowly into the casting You may not be able to get Good quality casting. To maintain in molten stage low temp of heat should be maintained between
415-425degrees celcius. How much of LDo is require we cannot say because it depends upon the conditions of Melting and temp of surroundings & Quantity.
Murthy
Bangalore

Heat reqd. = 1910/0.5 = 3820 kcal/hr.

GCV of LDO = 9450 kcal/ltr.

combustion efficiency assumed = 0.7

NCV of LDO= 9450 x 0.7 = 6615 kcal/ltr.

LDO consumption = 3820/6615 = 0.58 ltr.

Cost of LPG @ Rs. 58.00/ltr. = Rs. 20.88/hr.

Cost of LDO @ Rs. 35.00/ltr. = Rs. 20.30/hr.

Even though it seems LPG is costlier on paper, it is more viable because of other advantages, like cleaner fuel, eco-friendly, ISO certified, better automation & controllability, absence of pilferage etc.

In our company, we have been converting existing heating systems, such as Electricity, FO, LDO, Diesel & even fire wood to LPG, successfully.