Thermoeconomic Analysis Of Steam System & Energy Medium Cost Assessment For Iron And Steel Plant

Energy system analysis remains hot topic due to that human energy consumption demand is increasing. The energy system analysis in early days focuses on the quantity of energy consumption. After the emergence of the concept of exergy, energy system analysis starts to combine the quantity and quality of energy. Further, thermoeconomic theory directly relates energy and economy by combining the concept of exergy and cost.This thesis can be classified into two parts, the first part deals with thermoeconomic analysis and diagnosis of steam network system while the second part is energy medium cost assessment for iron and steel plant.For the first part, thermoeconomic model is applied to two steam network system, namely boiler steam system and gas turbine steam system. Both system are analyzed by thermoeconomic model, besides, the gas turbine steam system is further diagnosed. At first, the physical structure and flow structure are defined for both system; then, the software EES is used to calculate the exergy value for each flow. And the exergy value will be input into the software TAESS for thermoeconomic analysis. TAESS can output fuel-product table, irreversibility, exergy cost and unit exergy cost as well as some figures describing the cost formation. At last, the software can also conduct diagnosis work for gas turbine system. The diagnosis is conducted between two states, namely reference state and operation state. The thermoeconomic diagnosis can not only locate the malfunction but also quantify the effect of malfunction. And the extra fuel can be related with irreversibility, product and residue change.For the second part, the cost of energy medium in iron and steel plant is calculated. Iron and steel plant consumes a lot energy resource and many energy efficiency technologies are being investigated. But the energy efficiency through management is also important. The iron and steel industry in China is overcapacity and has lots of companies and quite fierce competition, thus the price of energy medium is artificially lowered in order to decrease production cost. But the price of energy medium violates the value of product and dissociate with market. In this investigation, thermoeconomic model is used to calculate the cost of energy medium in order to pave the way for further pricing of energy medium. The cost of the energy medium is: Coke oven gas 0.924 ?/m3, converter gas 0.413 ?/m3, high pressure steam 141 ?/t, middle pressure steam 108 ?/t, low pressure steam 68 ?/t and electricity 0.45 ?/kWh.