1-What do you
mean by Slop or Spent wash?
Slop or Spent wash also known as Vinasse is an acidic
effluent produced in Distillery unit. Slop is formed on fermentation of Sugar
cane molasses in distillery.
2-Why do you
treat Slop as a Hazardous effluent?
Because it is an acidic effluent having pH around 4 to 5
3-What are the
standard parameters of Slop or Spent wash?
- Colour : Brown
- Odour : Pungent
- pH : 4 to 5
- Solids: 9 to 12%
- BOD : 45000 to 60000
- COD : 110000 to 1350000
- Disposal methods:
- Biomethanation
- Composting
- Incineration Technology
Incineration technology method leads to Zero Liquid
Discharge, where spent wash is concentrated by heating it in specially designed
Boilers.
6-What are the
benefits of burning Slop in Boilers?
Benefits:
- Zero liquid discharge (ZLD) or Zero effluent discharge (ZED)
- Steam generated in Boilers can be used for Distillery process
- Power generation to fulfil auxiliary power of distillery, hence reduction in production cost.
- Ash generated is of potash reach which is good manure
7-What are the
challenging situations for designing the Spent wash Boilers?
- Slop & its ash characteristics
- Design of combustion system for Slop
- Design of combustion system for supporting fuel
- Design of pollution control equipments
Because it is a liquid fuel having very low GCV up to 1800
kcal/kg & high ash & moisture content.
9-What are the
various supporting fuels used in Incineration Boilers?
- Spent wash + Coal (Indian/Imported)
- Spent wash + Rice husk
- Spent wash + Bagasse
- Travelling grate Boiler: Rice husk & Bagasse
- AFBC Boiler: Indian & Imported coal
AFBC Boiler:
- Bottom supported
- Single drum
- Over bed feeding
- 3-pass flue gas construction
- Combustor is located in pass-1 & Super heater, Evaporator; Economiser & Super heaters are located in Pass-3
Combustor:As discussed above, Combustor
is located in Pass -1, fabricated with high temperature refractory material,
enclosed by steel casing and supporting structure. Combustor is divided into
various compartments & for all compartments ash drain system is provided.
Coal feeding system: consists of coal
bunker, VFD screw feeders to feed the coal. Coal is distributed inside the
combustor by pneumatic spreading system.
Spent wash feeding system: Concentrated
and pre-heated Spent wash from the storage tank is conveyed to boiler through
variable speed pump. Spent wash is sprayed over the fluidising bed at first
pass through spray guns.
13-Where do the
Secondary air & spent wash nozzles are provided in AFBC Boilers?
Secondary
air system is provided at 2 to 3 locations at various heights at furnace. And
spent wash nozzles provided just below the secondary air nozzles
14-What are the
various online cleaning mechanisms are provided for pressure parts?
Mechanical
rapping systems for super heaters
Soot
blowers for Evaporators
Sonic
soot blowers for Economisers
15-How do the
spent wash concentration (Brix) & its calorific values are related?
GCV
of the spent wash increases with increase in its concentrations
Sl No.
|
Brix (%)
|
GCV (Kcal/kg)
|
1
|
40
|
850
|
2
|
45
|
1200
|
3
|
50
|
1400
|
4
|
60
|
1800
|
16-How do you
increase the Brix of Spent wash?
Spent
wash Brix can be increased by heating
17-What
parameters of Brix are recommended for efficient burning?
- Brix: 55 to 60%
- Moisture: 40 to 50%
- Ash: 18 to 20%
- GCV: 1550 to 1750 kcal/kg
18-Write down
the ultimate analysis parameters of Spent wash
- Ultimate analysis report:
- Carbon: 18.5 to 23%
- Hydrogen: 1.5 to 2.5%
- Oxygen: 12 to 15%
- Nitrogen: 1.5 to 2%
- Sulphur: 0.5 to 0.7%
Ash contents
analysis by weight is as follow
- Silica (SiO2) : 2.3 to 2.8%
- Iron Oxide (Fe2O3) : 2 to 2.5%
- Calcium Oxide (Cao) : 12 to 16%
- Magnesium oxide (MgO) : 6 to 7%
- Sulphate, SO3: 15 to 17%
- Phosphate (P2O5) : 8 to 12%
- Potassium Oxide (K2O) : 45 to 50%
- Chlorides: 0.8 to 1.2%
It
is around 8 to 10 kg of steam is generated per square meter of heating surface
21-What is the quantity of steam generated per
square meter of heating surface in Spent wash Biomass (Bagasse, rice husk etc)
fired boilers?
It
is around 10 to 12 kg of steam is generated per square meter of heating surface.
Note:
For incineration:AFBC Boilers have more heating surface as compared to Biomass
fired Boilers
22-Why do the Spent wash Boilers have taller
furnaces?
Because;
- To maintain higher residence time in furnace up to 8 seconds
- To maintain optimum flue gas temperature at super heaters inlet to avoid coils fouling due to alkali ash property and to avoid corrosion of super heater coils due to chlorides (1%) in ash
In
spent wash Boilers APH are designed for air flow through tubes & flue gas
outside to avoid choking of tubes
24-What is the flue gas temperature that we get at
APH outlet for spent wash fired Boilers?
It
is around 180 to 200 Deg C
25-What is the size & density of refractory
materials used in Spent wash AFBC Boilers?
Size
of refractory materials is around 0.8 to 2.5mm. And density is around 1000 to
1100 kg/m3
26-What are the main compositions of Refractory
materials?
Questions & Answers on AFBC Boilers
- Silica 55 to 60%
- Alumina 35 to 40% & small traces of Feo, Mno, Cao, Mgo, P2O5 etc
27-What is the optimum temperature of spent wash at
the nozzle inlet?
It
is around 70 to 80 deg c
28-What is the maximum efficiency that we can get
for spent wash & Rice husk fired Boilers?
It
is around 72%
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Please let me know what is the use of fly ash obtained from spent wash incinirator in distillaries what is the composition of that ash how we check it
ReplyDeleteAs we know that spent wash ash is potassium rich hence it supply to further processing in which hazardous chemical remove and then uses for farming purposes
DeleteCan fire side chemical be effective for spent wash fuel
ReplyDelete