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相对于金属氧载体,CaSO4作为氧载体用于化学链燃烧,具有成本低、来源广泛和氧传递容量大等诸多优点,但是气相SO2以及各种固相硫沉积物对CaSO4用于化学链燃烧过程造成很大的障碍。基于热力学模拟,对CaSO4氧载体与以合成气为燃料的化学链燃烧进行了模拟研究,结果表明就CaSO4与合成气的反应而言,在燃料反应器中,100℃~400℃的低温反应条件下,主要发生的是合成气中CO和H2的甲烷化反应以及硫酸盐热化学还原反应,反应产物主要是H2S和CaCO3;在400℃~915℃,主要发生的是CO和H2与CaSO4的还原反应,还原产物是CaS和CO2;当反应温度高于915℃时,诸多副反应开始发生,反应物相除了CaS和CO2外,CaO等副产物开始出现;而在空气反应器中,在CaS的整个氧化过程中,CaS再生形成CaSO4的反应都是主要的,但是当空气过量系数ФAR<0.8时,CaSO4与CaS的固相反应以及CaS氧化形成CaO的两个副反应也同时起作用。在燃料反应器中,最优的反应条件是反应温度915℃、常压并严格控制CaSO4的加入量并确保CaSO4氧载体过量系数ФFR~1;而在空气反应器中,提供充足的空气量对于CaS的氧化非常重要,空气过量系数ФAR≥1不仅能确保CaS的充分氧化,而且还能避免CaS氧化过程中SO2的排放和CaO的产生。
Relative to the metal oxygen carrier, CaSO4 as an oxygen carrier for chemical chain combustion, with low cost, wide range of sources and oxygen delivery capacity and many other advantages, but the gas phase SO2 and various solid sulfur deposits CaSO4 for chemical chain combustion process Cause great obstacles. Based on the thermodynamic simulations, a simulation study was carried out on the chemical combustion of CaSO4 with the carrier gas of syngas. The results showed that in the reaction of CaSO4 with syngas, the reaction conditions of 100 ℃ ~ 400 ℃ , The main occurrence is the methanation of CO and H2 in the syngas and the thermochemical reduction reaction of sulfate, the reaction products are mainly H2S and CaCO3; at 400 ℃ ~ 915 ℃, the main reduction is the reduction of CO and H2 with CaSO4 Reaction, the reduction products are CaS and CO2; when the reaction temperature is higher than 915 ℃, many side reactions begin to occur, the reactants except CaS and CO2, CaO and other by-products began to appear; and in the air reactor, CaS During the whole oxidation process, the reaction of CaS regeneration to form CaSO4 is the main one. However, when the air excess coefficient ФAR <0.8, the two side reactions of CaSO4 with CaS and the CaO oxidation to CaO also play a role. In the fuel reactor, the optimum reaction conditions are reaction temperature 915 ℃, atmospheric pressure and strict control of the addition amount of CaSO4 and ensure the CaSO4 oxygen carrier excess coefficient ФFR ~ 1; while in the air reactor, providing enough air volume for The oxidation of CaS is very important. The air excess coefficient ФAR≥1 can not only ensure the sufficient oxidation of CaS, but also avoid the emission of SO2 and CaO during the oxidation of CaS.