# Gestão de Energia: 2013/14 Class # 4 Energy Analysis: Block diagrams Prof. Tânia Sousa

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Gestão de Energia: 2013/14 Class # 4 Energy Analysis: Block diagrams Prof. Tânia Sousa taniasousa@ist.utl.pt

Energy Analysis Definition: the process of determining the energy intensity of a product or service, i.e., the energy required directly and indirectly to produce it –The energy used indirectly might be more important that the energy used directly Auto-industry assembly line Electricity Paint

Energy Analysis Questions we can answer with an Energy Analysis: –What is the energy needed to produce 1 kg of steel? –How much energy is saved by recycling waste glass produced inside a glass factory back to the furnace? –What is the embodied energy of food consumed in Sweden and the UK? (1 MJ = 0.024 kgoe)

Energy Analysis Difficulties associated with the Energy Analysis framework: –Choosing the system boundary –Merge several kinds of energy Ex: the production of fueloil from crude oil has a much higher efficiency than the production of electricity from coal –Energy Credit for by-products Ex: by-products from the iron & steel industry are used by the cement industry

Energy Analysis: Basic Operations Unitary Production Operation Conventions: –The use of block letters for Operations –The use of numbers for Inputs/Outputs Operation A m2m2 m3m3 mRmR EAEA Materials lnput Production Energy consumption Residues m1m1

Energy Analysis: Specific Consumption of Operation & Inputs Specific Consumption of Operation A: CE A Specific Consumption of Material 1: CE 1

Energy Analysis: Mass Factors Residue formation factor Mass proportion

Energy Analysis: Specific Consumption of Production What is the energy specific consumption of m 3 ?

Energy Analysis: Specific Consumption of Production What is the energy specific consumption of m 3 ? Write it as

Energy Analysis: Specific Consumption of Production What is the energy specific consumption of m 3 ? Write it as Direct Energy Use Indirect Energy Use

Energy Analysis: Specific Consumption of Production What is the energy specific consumption of m 3 ? What is the specific consumption of residues?

Energy Analysis: Specific Consumption of Production What is the energy specific consumption of m 3 ? The specific consumption of residues is null No energy consumption is attributed to m R (which is also an output of operation A)

Energy Analysis: Specific Consumption of Production What is the energy specific consumption of m 3 ? –Why does a higher residue formation factor, S A, implies a higher specific consumption of the useful output, CE 3 ?

Energy Analysis: Sequential Process What is the energy specific consumption CE 4 ? BAC 2341 EAEA EBEB ECEC

Energy Analysis: Sequential Process What is the energy specific consumption CE 4 ? Write it as a function of: BAC 2341 EAEA EBEB ECEC

Energy Analysis: Sequential Process What is the energy specific consumption CE 4 ? BAC 2341 EAEA EBEB ECEC

Energy Analysis: Sequential Process What is the energy specific consumption CE 4 using this exterior boundary? BAC 2341 EAEA EBEB ECEC

Energy Analysis: Sequential Process What is the energy specific consumption CE 4 using this exterior boundary? Homework: Prove that this expression is equal to BAC 2341 EAEA EBEB ECEC

Exercise Consider the production system of floor pavement that has only: a ceramic oven, choice of defective parts and storage. The specific consumption of the furnace is 200 kJ / kg, whereas the specific energy consumption of the choice operation is 5 kJ / kg and the specific energy consumption of storage operation is 20 kJ / kg. The floor raw material involved an energy consumption of 50 kJ / kg in the clay processing operations. The operation of cooking promotes the volatilization of certain components of raw pavement representing 5%. The operation of choice rejects 10% of the output of the furnace and breaks during storage are 1%. Determine the specific consumption of the floor pavement.

Exercise Scheme CE A = 200 kJ/kg; CE B = 5 kJ/kg; CE C = 20 kJ/kg CE 1 = 50 kJ/kg; S A = 1/0.95; S B = 1/0.9; S C = 1/0.99 ChoiceOvenStorage 2341 EAEA EBEB ECEC

Energy Analyis: Convergent Process What is the energy specific consumption CE 5 ? A B C 5 4 2 3 1

Energy Analyis: Convergent Process What is the energy specific consumption CE 5 ? A B C 5 4 2 3 1

Exercise A company manufacturing sunflower oil imports 60% of raw material and the remaining 40% is domestically produced. The sunflower imported is transported by sea 1000 km, while the national sunflower is transported by truck 200 km. The operation of oil refining has a specific consumption of 100 kJ/kg. The oil content of sunflower is 10%, meaning that the rejection mass on refining is 90% (in fact this material is used in the manufacture of cattle feed). The specific consumption of transport is 0.025 kJ/kg.km by truck and 0.010 kJ/kg.km by sea. Losses in sunflower transportation are 1% on truck and 0.1% on ship. Determine the specific consumption of refined oil.

Exercise Scheme CE A =1000  0.01 kJ/kg; CE B =200  0.025 kJ/kg; CE C =100 kJ/kg; S A = 1/0.999; S B = 1/0.99; S C = 1/0.1; CE 1 = CE 3 = 0; A: Transport ship B: Transport truck C: Refining 5 4 2 3 1

Energy Analyis: Divergent Process In a divergent process all products that are an output of the same operation have the same specific energy consumption –There are other options to give energy credit to by- products, e.g., economic. B C A 3 5 2 4 1

Energy Analyis: Divergent Process What are the energy specific consumptions CE 5 & CE 3 ? B C A 3 5 2 4 1

Energy Analyis: Divergent Process What are the energy specific consumptions CE 5 & CE 3 ? B C A 3 5 2 4 1

Exercise Compute CE 11 and CE 12 D E C G A 11 10 9 7 5 2 F 1 4 B 3 6 128

Exercise Compute CE 11 and CE 12 D E C G A 11 10 9 7 5 2 F 1 4 B 3 6 128

Energy Analysis: Treatment Operation What is the energy specific consumption CE 2 ? Energy consumption in a treatment operation is assigned to the operation that generates the residues (A)

Energy Analysis: Treatment Operation What is the energy specific consumption CE 2 ?

Energy Analysis: Treatment Operation What is the energy specific consumption CE 2 ? What is the energy specific consumption CE 3 ?

Energy Analysis: Treatment Operation What is the energy specific consumption CE2? What is the energy specific consumption CE3? –The energy specific consumption of the output from the treatment operation is null

Energy Analysis: Recycling What is the specific consumption of production CE 2 ? Operation A m 1 m 2 m R E A Materials input Production Energy consumption Residues Treatment operation B m 3 Recycled residues E B Energy consumption in treatment Recycling operation C m4m4

Energy Analysis: Recycling What is the specific consumption of production CE 2 ? Other recycling schemes: Operation A m 1 m 2 m R E A Materials input Production Energy consumption Residues Treatment operation B m 3 Recycled residues E B Energy consumption in treatment Recycling operation C m4m4

Exercise Compute CE 6 B 3 C (treat) D A 4 R 6 1 2 5

Exercise Compute CE 6 B 3 C (treat) D A 4 R 6 1 2 5

Energy Analyis: Energy & material inputs What is the meaning of E 1 ? –E 1 is the total energy used to produce m 1 For consistency purposes what should be the meaning of E A ?

Energy Analyis: Energy & material inputs What is the meaning of E 1 ? –E 1 is the total energy used to produce m 1 For consistency purposes what should be the meaning of E A ? –E A should be the total energy used to produce that energy consumption, i.e., E A should be the primary energy associated with the final energy input –To merge several kinds of final energy first convert each one to primary energy and then make the sum

Energy Analyis: Energy efficiency measures What is the impact of an energy efficiency measure that decreases CE A on CE output ? BAC 2341 EAEA EBEB ECEC 4 B A 2 3 5 1 EAEA EBEB ECEC C D EDED 6

Energy Analyis: Energy efficiency measures What is the impact of an energy efficiency measure that decreases CE A on CE output ? BAC 2341 EAEA EBEB ECEC 4 B A 2 3 5 1 EAEA EBEB ECEC C D EDED 6

Exercise A factory produces 2 end products: P1 and P2. These products follow the production process shown in the diagram below, with P1 = 50000 ton/year and P2 = 30000 ton/year. The operation G treats the effluents from E and F. These two (E and F) are the only productive operations that generate waste, and S E = 1.2, S F = 1.3. In operation G, only 20% of the input effluent, exits the process as waste. The values of composition are as follows: f 4 = 0.4, f 6 = 0.5. The table presents the specific consumption of each operation. Consider that for electricity: 0.215 kgep/kWh and for fueloil 0.984 kgep/kg. What is the specific consumption of each product? 8 (produção 1) A C D E B 2 1 F G 14 13 12 11 10 (produção 2) 3 4 5 6 7 9

Exercise

A factory produces 2 end products: P1 and P2. These products follow the production process shown in the diagram below, with P1 = 50000 ton/year and P2 = 30000 ton/year. The operation G treats the effluents from E and F. These two (E and F) are the only productive operations that generate waste, and S E = 1.2, S F = 1.3. In operation G, only 20% of the input effluent, exits the process as waste. The values of composition are as follows: f 4 = 0.4, f 6 = 0.5. The table presents the specific consumption of each operation. Consider that for electricity: 0.215 kgep/kWh and for fueloil 0.984 kgep/kg. In which product will a measure of energy savings implemented in the operation A reduce more the specific consumption? 8 (produção 1) A C D E B 2 1 F G 14 13 12 11 10 (produção 2) 3 4 5 6 7 9

Exercise

A factory produces 2 end products: P1 and P2. These products follow the production process shown in the diagram below, with P1 = 50000 ton/year and P2 = 30000 ton/year. The operation G treats the effluents from E and F. These two (E and F) are the only productive operations that generate waste, and S E = 1.2, S F = 1.3. In operation G, only 20% of the input effluent, exits the process as waste. The values of composition are as follows: f 4 = 0.4, f 6 = 0.5. The table presents the specific consumption of each operation. Consider that for electricity: 0.215 kgep/kWh and for fueloil 0.984 kgep/kg. Calculate f 13 8 (produção 1) A C D E B 2 1 F G 14 13 12 11 10 (produção 2) 3 4 5 6 7 9

Exercise 8 (produção 1) A C D E B 2 1 F G 14 13 12 11 50000 30000 10000 39000 9000 3800 15200 27600 41400 42400

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