CALORIFIC VALUE OF FUEL USING JUNKER’S GAS CALORIMETER

CALORIFIC VALUE OF FUELS y

y

y

It is defined as the heat liberated in kJ by complete combustion of 1 kg of fuel, solid or liquid. For gases it is the heat liberated in kJ per cubic metre at STP. For example: Fuel

kJ/kg

kCal/kg

Hydrogen

141900

33900

Butane

49200

11800

Diesel

45000

10700

Anthracite

27000

7800

Wood

15000

3600

Natural Gas

54000

13000

TYPES y

OF CALORIFIC VALUES

Higher Calorific Value:

It is the total heat liberated  when all the products of combustion are brought back to pre-combustion temperature and in particular, condensing any vapour produced. (kJ/kg)

Calorific Value: It is determined by  subtracting the latent heat of vaporization of the water produced from the Higher Calorific value. (kJ/kg) Thus, (HHV ) p = (LHV)p + m hfg (HHV )v = (LHV)v + m(ug  uf) y

Lower

COMPARISON OF HCV AND LCV y

Here

is a comparison of  HC V  and LC V  of some fuels.

FUEL

HCV

(MJ/kg)

HCV

(kj/mol)

LCV

(MJ/kg)

Hydrogen

141.80

286.00

121.00

Butane

49.50

20900

45.75

Gasoline

47.30

-

44.40

Propane

50.35

2220

46.35

Anthracite

2700

-

-

Kerosene

46.20

-

43.00

Paraffin

46.00

-

41.50

THE

JUNKERS GAS CALORIMETER

APPARATUS The apparatus mainly consists of a cylindrical shell with copper coil arranged in two pass configuration with water inlet and outlet to circulate through the copper coil, a pressure regulator, a wet type gas flow meter & a gas Bunsen burner, temperature sensors for measuring inlet, outlet water temperature, and for flue gas temperature and a measuring jar.

WORKING PRINCIPLE This Gas Calorimeter works on the Junker's principle of burning of a known volume of gas and imparting the heat with maximum efficiency to steadily flowing  water and finding out of the rise in temperature of a measured volume of water. The formula, Calorific  V alue of Gas X  V olume of Gas =  V olume of water X Rise in Temperature, is then used to determine the Calorific  V alue of the Gas (assuming that heat capacity of water is unity).

DETERMINATION OF CALORIFIC VALUE y

y

y

This Calorimeter covers a wide range between 120 BTU (1000 to 26000 K Cal/m3). The Calorimeter is fixed on a tripod stand having levelling screws to keep the Calorimeter in perfectly   vertical position.  A constant water head maintenance device provided in the feed water pipe along with the inlet water flow regulator is fixed to the outer housing of the calorimeter.

PROCEDURE(Contd.) y

y

y

y

The gas source is connected to the pressure regulator, gas flow meter and the burner respectively in series. The water and gas flows are started to flow at a constant rate and the burner is lighted outside the calorimeter. The gas flow is regulated at a steady state to any  designed flow (volume). The burner is inserted into the calorimeter and the outlet water is allowed to attain a steady temperature.

PROCEDURE(Contd.) y

y

The outlet is let into a 1000mL flask and started and the initial gas flow rate is noted. The time taken for the 1000mL flask to be filled and the final gas f low rate is also noted.

FORMULA TO BE USED C V g=(  V w x w x CPw x T ) /  V g x g  where w is the density of water  w is the volume of water collected in litres  V  CPw is the specific heat of water T is the change in temp. of water  V g is the volume of gas burnt in litres g is the density of the gas burnt

APPLICATIONS y y y y y y y

Petroleum Industries Coke Oven Batteries Thermal Power Houses Cement Industries Fuel Gas Producers & Consumers Steel Plants Fertilizer Units