بهينه‌سازي سودمندي‌ ـ اقتصادي سيستم تركيبي توليد نيرو به‌كمك گاز‌ساز بستر سيال

EXERGOECONOMIC OPTIMIZATION OF COMBINED HEAT AND POWER SYSTEM INCORPORATING FLUIDIZED BED GASIFIER

امروزه كاربرد ضايعات زيست‌توده‌يي انرژي كافي براي توليد انرژي الكتريكي، كاربرد‌هاي مربوط به موتور و ... را فراهم مي‌كند. در فرايند گازي‌كردن، زيست‌توده را در حضور هوا و رطوبت به گاز تميز و قابل احتراق تبديل مي‌كنند. يكي از روش‌هاي گازي‌كردن زيست‌توده استفاده از گازساز بستر سيال است. سيستم تركيبي توليد نيرو با استفاده از گازساز بستر سيال و توربين گاز از روش‌هاي موجود براي توليد انرژي الكتريكي است كه در مقايسه با ديگر سيستم‌ها از بازدهي بيشتر و هزينه‌ي تمام‌شده‌ي كم‌تر برخوردار است. در اين نوشتار، مدل ترموديناميكي بستر سيال به‌منظور سوزاندن ضايعات زيست‌توده‌يي و توليد گاز از آن بررسي، و سيستم تركيبي توليد نيرو محتوي بستر سيال پرفشار به‌لحاظ سودمندي‌ـ اقتصادي تحليل شده است. همچنين به‌منظور به‌منظور بهينه‌سازي هزينه‌ي سيستم مذكور، بهينه‌سازي سودمندي‌ ـ ‌اقتصادي تجزيه و تحليل شده است.

Biomassʹs utilization provides sufficient energy, which can be used for electricity generation, engine applications and etc. In the gasification process, biomass will be converted into clean and combustible gas in the presence of steam and air. In this paper, a model is presented for the gasification of refused derived fuel (RDF) particles in a bubbling fluidized bed gasifier (BFBG). The model combines the chemical and thermodynamic equilibrium of the global reaction, predicting the final composition of the product gas. Once the composition of the produced gas is obtained, a range of parameters can be derived, such as the exergetic efficiency of the gasifier and the heating value of the product gas, as well as the cold gas efficiency of BFBG. A parametric study of the effect of the gasifying relative fuel/air ratio, gasifying temperature and the moisture content of the RDF on the characteristics of the process and the producer gas composition, is conducted. The model shows good agreement with the experimental results. The model helps to predict the behavior of different biomass types and is a useful tool for optimizing the design and operation of bubbling fluidized bed gasification. Furthermore, thermodynamic analyses (both energy and exergy) have been conducted for a combined system power plant, in which the investigated system consists of a pressurized fluidized bed gasification unit gasifier. In addition, an exergoeconomic evaluation is performed to determine all mass flow rates, exergy flow rates, exergy destruction flow rates, component exergetic efficiencies, exergetic cost flow rates, mass cost flow rates, component product and fuel specific exergetic and mass costs, exergy destruction cost flow rates, component investment cost flow rates, and system total cost. Finally, the exergoeconomic optimization of the mentioned system is performed with the SPECO method.