Use material and energy balances to calculate the mass flow rates (tonnes/day) of Streams B, C, D, E, F, G and H, and heat flows Q0, Q1, Q2, Q3, and Q4 (kJ/day). Take the molecular weight of air to be 29.0. (Caution: Before you start doing lengthy and unnecessary energy balance calculations on the boiler furnace, remember the given furnace efficiency.)
Use material and energy balances to calculate the mass flow rates (tonnes/day) of Streams B, C, D, E, F, G and H, and heat flows Q0, Q1, Q2, Q3, and Q4 (kJ/day). Take the molecular weight of air to be 29.0. (Caution: Before you start doing lengthy and unnecessary energy balance calculations on the boiler furnace, remember the given furnace efficiency.)
Introduction to Chemical Engineering Thermodynamics
8th Edition
ISBN:9781259696527
Author:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Publisher:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Chapter1: Introduction
Section: Chapter Questions
Problem 1.1P
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Use material and energy balances to calculate the mass flow rates (tonnes/day) of Streams B, C, D, E, F, G and H, and heat flows Q0, Q1, Q2, Q3, and Q4 (kJ/day). Take the molecular weight of air to be 29.0. (Caution: Before you start doing lengthy and unnecessary energy balance calculations on the boiler furnace, remember the given furnace efficiency.)
![**9.83 Environmental Application**
*The wastewater treatment plant at the Ossabaw Paper Company paper mill generates about 24 tonnes of sludge per day. The consistency of the sludge is 35%, meaning that the sludge contains 35 wt% solids and the balance liquids. The mill currently spends $40/tonne to dispose of the sludge in a landfill. The plant environmental engineer has determined that if the sludge consistency could be increased to 75%, the sludge could be incinerated (burned) to generate useful energy and to eliminate the environmental problems associated with landfill disposal.*
*The flowchart for a preliminary design of the proposed sludge-treatment process follows. For simplicity, we will assume that the liquid in the sludge is just water.*
![Flowchart Image]
### Process Description:
The sludge from the wastewater treatment plant (Stream A) passes through a dryer where a portion of the water in the sludge is vaporized. The heat required for the vaporization comes from condensing saturated steam at 4.00 bar (Stream B). The steam fed to the dryer is produced in the plant's oil-fired boiler form feedwater at 20°C (Stream C). The heat required to produce the steam is transferred from the boiler furnace, where fuel oil (Stream D) is burned with 25% excess air (Stream E). The concentrated sludge coming from the dryer (Stream F), which has a consistency of 75%, is fed to an incinerator. The heating value of the sludge is insufficient to keep the incinerator temperature high enough for complete combustion, so natural gas (Stream G) is used as a supplementary fuel. A stream of outside air at 25°C (Stream H) is heated to 110°C and fed to the incinerator along with the concentrated sludge and natural gas. The waste gas from the incinerator is discharged to the atmosphere.
### Detailed Component Breakdown:
- **Fuel oil**: The oil is a low-sulfur No. 6 fuel oil. Its ultimate (elemental) analysis on a weight basis is 87% C, 10% H, 0.84% S, and the balance oxygen, nitrogen, and nonvolatile ash. The higher heating value of the oil is 3.75 x 10^4 kJ/kg and the heat capacity is \(C_p = 1.8 \text{ kJ/(kg · °C)} \).
- **Boiler**: The boiler has](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Ff6ab806b-464c-4756-9d8f-72da0489465e%2F0aa45037-445c-4812-8df3-d9fc59ce987e%2F812wnpe_processed.png&w=3840&q=75)
Transcribed Image Text:**9.83 Environmental Application**
*The wastewater treatment plant at the Ossabaw Paper Company paper mill generates about 24 tonnes of sludge per day. The consistency of the sludge is 35%, meaning that the sludge contains 35 wt% solids and the balance liquids. The mill currently spends $40/tonne to dispose of the sludge in a landfill. The plant environmental engineer has determined that if the sludge consistency could be increased to 75%, the sludge could be incinerated (burned) to generate useful energy and to eliminate the environmental problems associated with landfill disposal.*
*The flowchart for a preliminary design of the proposed sludge-treatment process follows. For simplicity, we will assume that the liquid in the sludge is just water.*
![Flowchart Image]
### Process Description:
The sludge from the wastewater treatment plant (Stream A) passes through a dryer where a portion of the water in the sludge is vaporized. The heat required for the vaporization comes from condensing saturated steam at 4.00 bar (Stream B). The steam fed to the dryer is produced in the plant's oil-fired boiler form feedwater at 20°C (Stream C). The heat required to produce the steam is transferred from the boiler furnace, where fuel oil (Stream D) is burned with 25% excess air (Stream E). The concentrated sludge coming from the dryer (Stream F), which has a consistency of 75%, is fed to an incinerator. The heating value of the sludge is insufficient to keep the incinerator temperature high enough for complete combustion, so natural gas (Stream G) is used as a supplementary fuel. A stream of outside air at 25°C (Stream H) is heated to 110°C and fed to the incinerator along with the concentrated sludge and natural gas. The waste gas from the incinerator is discharged to the atmosphere.
### Detailed Component Breakdown:
- **Fuel oil**: The oil is a low-sulfur No. 6 fuel oil. Its ultimate (elemental) analysis on a weight basis is 87% C, 10% H, 0.84% S, and the balance oxygen, nitrogen, and nonvolatile ash. The higher heating value of the oil is 3.75 x 10^4 kJ/kg and the heat capacity is \(C_p = 1.8 \text{ kJ/(kg · °C)} \).
- **Boiler**: The boiler has
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