For the sketch shown on page 20-67 in Figure P-20-23 , perform a heat balance on the dig...

For the sketch shown on page 20-67 in Figure P-20-23 , perform a heat balance on the digester designed in Problem 20-21. Is enough methane produced to heat the digester in January if the mean ambient temperature is 15 C? Assume optimistic heat transfer coefficients for the building materials and a heat exchanger efficiency of 90%. The temperature of the sludge is 12C.

Problem 20-21

Determine the dimensions of Sunset’s anaerobic digester designed in Problem 20-19. Assume a depth of 7.5 m and a bottom slope of 1:6. Provide a floating cover. The floating cover diameters are sold in 1.5 m increments.

Problem 20-19

In the preliminary analysis of alternatives for stabilizing the WAS sludge from Sunset’s activated sludge plant your boss has asked you to design an anaerobic digester. Determine the volume of the digester, the flow rate of methane, and the volume of an external tank pressurized to 350 kPa. Use the data from Problem 20-17 and the following data for this design:

Problem 20-17

In the preliminary analysis of alternatives for stabilizing the WAS sludge from Sunset’s activated sludge plant, your boss has asked you to design an aerobic digester. The sludge flow rate is 62.3 m³/d. The solids concentration is 2.8%, and the specific gravity of the sludge is 1.01. Use the following data for the design: