project K:Research2

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(Digester)
(Calculations)
 
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* Food waste has a higher solid content than municipal wastewater, meaning that it is a more efficient use of digerester volume aka the digester can be smaller.
 
* Food waste has a higher solid content than municipal wastewater, meaning that it is a more efficient use of digerester volume aka the digester can be smaller.
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for 100 tons of “input”, 30 tons of “output” will then be composted
 
Thus, 30% of input volume can be used for compost--> design constraint for a compost bin or hints at how many plants to have.
 
  
* Biogas composition is about 67% methane (CH4), 33% CO2
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* 100 tons of “input” will create 30 tons of “output” for composting
thus the heat capacity is 670 BTU/Ft3 burned.
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* Biogas composition is about 67% methane (CH4), 33% CO2 - so heat capacity is 670 BTU/Ft3 burned.
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* CH4 production rate (ft3/lb)= CH4% X Gas Production ( ft3/day) TS% X Feed (gal/day) X 8.34 lbs per gal
 
* CH4 production rate (ft3/lb)= CH4% X Gas Production ( ft3/day) TS% X Feed (gal/day) X 8.34 lbs per gal
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1 ft3 CH4 at 67% methane = 670 BTUs and 13,400 BTUs = 1 kWh. this value is better than coal ( 10, 500btu/kwh)
 
1 ft3 CH4 at 67% methane = 670 BTUs and 13,400 BTUs = 1 kWh. this value is better than coal ( 10, 500btu/kwh)
  
av. of 2,300 ft3 per day/ 1,000 ft3 digester volume
 
range (in ft3/day) = (1,100–3,200)  with these figures, 4.79 kw/h of energy are created daily in a 1000ft3 digester! thats enough to run 48 100-watt lightbulbs continuously*
 
  
*these figures are the optimal output based on the chemical energy of the gas, not the conversion into electric energy by burning.
+
 
 +
*av. of 2,300 ft3 per day/ 1,000 ft3 digester volume
 +
range (in ft3/day) = (1,100–3,200)  with these figures, 4.79 kw/h of energy are created daily in a 1000ft3 digester! thats enough to run 48 100-watt lightbulbs continuously. These figures are the optimal output based on the chemical energy of the gas, not the conversion into electric energy by burning.
  
 
1000ft3= 28.3 cubic meters
 
1000ft3= 28.3 cubic meters

Latest revision as of 18:01, 30 November 2011

PROCESS

Calculations

  • Food waste has a higher solid content than municipal wastewater, meaning that it is a more efficient use of digerester volume aka the digester can be smaller.


  • Peak methane production in a 15-day cycle, themophyllic digester was 10.8L/hr but averaged 4.8L/hr.


  • 100 tons of “input” will create 30 tons of “output” for composting


  • Biogas composition is about 67% methane (CH4), 33% CO2 - so heat capacity is 670 BTU/Ft3 burned.


  • CH4 production rate (ft3/lb)= CH4% X Gas Production ( ft3/day) TS% X Feed (gal/day) X 8.34 lbs per gal

peak values near 8.5 ft3 CH4/ lb food waste. 5ft3/lb average.

1 ft3 CH4 at 67% methane = 670 BTUs and 13,400 BTUs = 1 kWh. this value is better than coal ( 10, 500btu/kwh)


  • av. of 2,300 ft3 per day/ 1,000 ft3 digester volume

range (in ft3/day) = (1,100–3,200) with these figures, 4.79 kw/h of energy are created daily in a 1000ft3 digester! thats enough to run 48 100-watt lightbulbs continuously. These figures are the optimal output based on the chemical energy of the gas, not the conversion into electric energy by burning.

1000ft3= 28.3 cubic meters

Digester

1. There are certain minimum dimensions

2. It needs constant teperature

3. Position: above or below ground.


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