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ABSTRACT
Greenhouse gases (Gags) are one of the main reasons behind the Earth warming. In Iran, the majority of power plants utilize fossil fuels for generating electricity. And also, the production of Gags from the fossil fuels is very high. Gas production system (GPS) is found to be a good candidate for lowering the amount of Gags produced. Therefore, in this study, the optimal size and operation of different GPSs used in a combined cool, heat, and power system are investigated. Particle swarm optimization algorithm is used for optimization. The results show that the sewage sludge GPS with reciprocating engine (RE) has the lowest payback period. In addition, the RE has the highest pollution cost under the condition of selling electricity to the electrical network.
Nomenclature
| = | The dryer surface (m2) The GPS nominal capacity (m3) | |
| = | Total cost for CCHP ($) The prime movers operating cost ($) | |
| = | The auxiliary boiler operating cost ($) The GPS operating cost ($) | |
| = | The prime movers investment cost ($) The absorption chiller investment cost ($) | |
| = | The GPS investment cost ($) The prime movers replacement cost ($) | |
| = | The absorption chiller replacement cost ($) The total pollution cost ($) | |
| = | The GPS capital cost ($/m3) The GPS operating and maintenance cost ($/kWh) | |
| = | The percentage of CH4 collected The total LGP cost ($) | |
| = | the LGP capacity (m3/h) The instruction cost ($/ton) | |
| = | The purchased land cost ($/m2) The total purchased power cost from the electrical network ($) | |
| = | The operating and maintenance cost ($/ton) Average constant pressure specific heat capacity (kJ (kg K)−1) | |
| = | Calorific value (MJ (N m3)−1) Dryer investment cost ($) | |
| = | Gasifier investment cost ($) Operating and maintenance cost for gasifier ($) | |
| = | The demand cost of the electrical load The PM capital cost ($/kW) | |
| = | The PM nominal capacity (kW) The AC capital cost ($/kW) | |
| = | The AC nominal capacity (kW) The variable maintenance cost ($/kWh) | |
| = | The PM replacement cost ($) The percentage of CH4 oxidized | |
| = | Day Electricity sold, purchased, and production (kWh) | |
| = | Chemical energy (MJ) The PM produced electricity (kWh) | |
| = | The purchased electricity from the electrical network (kWh) The sold electricity to the electrical network (kWh) | |
| = | The maximum purchased power from the electrical network in the one month Recovery factor | |
| = | The GPS production energy (kWh) The total LGP gas for all lifetime (m3) | |
| = | The hourly required gas energy (kWh) Hourly production gas (m3h−1) | |
| = | The hourly production gas energy (kWh) Hour | |
| = | The production gas heating value (kWh/m3) Higher heating value of sewage sludge (MJ kg−1) | |
| = | Heat production (kWh) The heating value of the natural gas (kWh/m3) | |
| = | The boiler produced heat (kWh) Interest rate | |
| = | The income from selling electricity to the electrical network The constant that is for dryer with burner and without burner 289 and 93.2, respectively | |
| = | The decay rate of CH4 generation (year−1) The PM lifetime (year) | |
| = | The LGP potential (m3/ton) The wet wood input rate (kg/s) | |
| = | The wood input rate (kg/s) The operating lifetime (20 years) | |
| = | The month counter The purchasing power from electrical network pollution cost ($/kWh) | |
| = | The price of production gas ($/m3) The boiler pollution cost ($/kWh) | |
| = | The selling electricity to the electrical network pollution cost ($/kWh) The purchased electricity price from the electrical network ($/kWh) | |
| = | The prime movers pollution cost ($/kWh) Volumetric flow rate in STP (N m3 h−1) | |
| = | The natural gas price ($/m3) The system lifetime (year) | |
| = | The sold electricity price to the electrical network ($/kWh) The required land (m2/ton) | |
| = | The heat given to the woods (kW) The time since the municipal solid waste was landfilled | |
| = | The PM replacement factor Reference temperature (K) | |
| = | The LGP required land (m2) The total emission of CH4 (m3) | |
| SHP | = | Separate heat and power The yearly municipal solid waste weight (ton) |
| = | Gasifier outlet temperature (K) Molar ratio | |
| = | The electrical network The GPS efficiency | |
| = | The woods wet amount Hot gas efficiency | |
| = | The total municipal solid waste weight for all lifetime (ton) The PM efficiency | |
| = | The replacement number The boiler efficiency | |
| = | The dryer efficiency Sensible heat (MJ) | |
| = | Gasifier efficiency The average temperature between gas and wood (°C) |