Specifications for sulphur | Steam Requirement and E-melt system in sulphur melting
Abstract of Sulphur Melting :
1. Sulphur molecular formula “ S “ and it has an atomic number and atomic weight are 16 & 32.06 gm/mol respectively. It melt at 114oC temperature. It vaporizes at 444oC temperature when heated with air. Sulphur is available in the form of Granular, Rock Sulphur & Roll Sulphur. It is bright yellow, free from dart. Its density is 2.07 gm/cm -3 at 20 °C.
2. Specifications requirement
|1.||Elemental sulphur (%by mass )||99.50|
|2.||Moisture content,max (%by mass )||0.15|
|3.||Ash, max (%by mass )||0.20|
3. SO2 gas is produced by burning of sulphur with atmospheric air
4. Sulphitation is the process of purification of cane juice by employing milk of lime and sulphur dioxide gas.
5. Sulphur melt is feed to sulphur bunners along with air to produce sulphur dioxide gas. So sulphur maintained in liquid state in sulphur melter by using steam coils immersed in sulphur. It steam temperature used for steam coil is 145 to 150oC (pressure around 4.5 to 6 kg/cm2)
6. Sulphur Melter is a rectangular M.S. fabrication. It has three compartments for separation of settling and floating impurities. The compartments are designed with underflow and overflow arrangements, so that the impurities settle-down and float-up, through proper retention time.
7. Holding capacity of this melter is approximately 24hrs. Each compartment has its own steam coil with inlet and outlet arrangement.
1 liter of sulphur melt = 1.77 Kg of sulphur.
9. The molten sulphur is pumped from the melter to the furnace through a steam jacketed delivery line, which consists of one molten sulphur header with four isolation valves which are also steam jacketed, two for re-circulation of melt and one each for the two pumps outlets. The header is connected to the steam jacketed delivery line, which goes up to the top of the furnace for the melt to be injected into the furnace through a molten sulphur gun.
10. It is very important to maintain the temperature of steam jacketed line within 140-150oC for free flow of the melt.
11. For sulphur melting process generally using 7ata steam from boiler.
Steam Requirement of Sulphur melting Process:
Heat required for sulphur melting = Weight of the sulphur to be melted in kg x ( Specific heat of the sulphur x Temperature rise of sulphur + Latent heat of the melting
Q = M x [ (ΔT x Cp) + λ]
Q= Heat required for sulphur melting in Kcal /kg
M = Weight of the sulphur to be melted in kg
ΔT = Temperature of the granular sulphur and molten sulphur in oC
Cp = Specific heat of the sulphur in Kcal/kg/oC
λ = Latent heat of the melting in Kcal/ Kg
Take 5000TCD plant
Sulphur requirement 0.07 % on cane (Maximum)
M = Sulphur quantity requirement = 3500kgs
ΔT = 140 to 25 oC
Cp = 0.174Kcal/kg
λ= 9.4 Kcal/kg
Q = 102935Kcal
Latent heat of the steam = 489 Kcal/kg
Steam Required for melting = 210kg/hr ( Actual this is requirement for the day but melter holding capacity always having for 24hours so it is to be consider per hour)
Steam % Cane for sulphur melting = 0.10%
But in practical point of view extra taken due to radiation losses, venting losses etc. it is consider as 0.15 to 0.2% on cane (Depend on steam line length from boiler to sulphur melter)
While using E- melt system power requirement
1 KWH = 864Kcal
Power required for melting of Sulphur = 102935 / 864 = 120Kw ( Actual this power requirement is per day but steam required for continuously to maintained liquid state so the power vary from 60 to 120KWH )
Electrical Vapouriser System – (E-melt)
High pressure steam at 8 Kg/cm2 must be bled from the turbine or the Boiler PRDS system and brought over long distance to the Sulphur Burners through pipelines for melting of Sulphur. While transporting steam for this purpose, a lot of energy is lost due to condensation by radiation and convection. Electrical vapourisers (E-Melt) is one of the solution to overcome this problem in sugar mills.
Electrical vapourisers are also particularly suited for use during the start-up of the factory when the steam supply is erratic and because of which, during this period there is a problem in steady operation of Sulphur Burner system.
Features of E-Melt System :
1. While using this system the melting process is completely isolated from the main boiler of the factory. So while boiler unexpected stoppage time it will not effect the sulphur melting process.
2. The E-Melt system can be added on to the existing Sulphur melting system with only minimal modifications.
3. Common system for the complete Sulphur station
4. Can switch to factory steam in case of system breakdown, without disrupting the generation of So2
5. Effects considerable amount of energy saving,
6. Easy to install & can be located close to the point of use
Some Important things in E- Boiler or E-melt
a) Water Feed (Pump) Control and Low Water : Cutoff automatically maintains correct water level and shuts Off the vapourizer when the water level in the vapourizer drops below safe limits.
b) Gauge glass arrangement is to be done for E- boiler to know water level in boiler
c) Pressure Gauge provided for visual indication of steam pressure in the vapouriser.
d) Pilot Light visually indicates when vapouriser control circuit energized and the vapouriser is operating.
e) Condensate Return system for recovery of condensate from melt system to vapourizer allows as feed results in negligible water loss and make up requirement.
f) PID Control with electronic solid state relay tor maintaining vapour temperature and pressure accurately.
g) DM water (1st body condensate water) arrangement to be done for makeup water.
h) Steam coils oulet line valves is to be gate type valves.
i) Out line (return condensate line) header to be having minimum 3″ to 4″ dia at the collecting point.
j) Drain line with valve (1/2”) to be provided for oulet condensate line before the valve (To remove air lock)
k) Inlet and oulet steam lines, pump header and delivery lines insulation made to be perfect.
l) One drain line is to be provide for return condensate line just before the E – boiler inlet line valve.
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