太阳能熔融盐热化学循环制氢和合成气反应体系研究

STUDY ON THE THERMOCHEMICAL CYCLIC SYSTEM FOR HYDROGEN AND SYNTHESIS GAS PRODUCTION IN MOLTEN SALT USING SOLAR PROCESS HEAT

提出了一种新型的太阳能加热熔融盐化学循环反应体系，整个过程分两步：第一步，利用熔融碱金属碳酸盐吸收、储备、传输太阳能，在熔融盐介质中CH4与金属氧化物MxOy，反应生成相应的金属和合成气；第二步，金属分解水产生氢气和相应MxOy，从而MxOy，又循环到第一步再利用。根据最小吉布斯自由能原理，采用化学热力学计算软件HSCChemistry5．1，对CH4与几种MxOy，气-固相反应的△G^o进行了计算和分析，进一步分析了在熔融碱金属碳酸盐（摩尔比为1：1的Na2CO3和K2CO3）体系中温度对反应产物平衡组分的影响。结果表明，理论上只有ZnO和SnO2适合该反应体系，其反应气体产物中合成气的量随反应温度的增加而增加，比较适宜的反应温度在1200K左右。计算结果表明100MW的太阳能能量系统至少可以提供每秒生产5．32kg液态金属Zn所需能量，实现每秒将3．6×10^4kJ的太阳能转化为化学能。

A novel thermochemical cyclic system for hydrogen and synthesis gas production using solar process heat was proposed. The whole cyclic process was divided into two steps in the technology. In the first step, solar energy was absorbed, stored and transmitted by molten alkali carbonate, methane reacted with metallic oxide（MxOy ） to form synthesis gas and metal in the molten salt medium; In the other step, M, Oy and H2 were produced from water decomposed by metal. Thus Mx Oy from this step was recycled to the first step. On the basis of Gibbs free energy minimization, the △ G^o analyzed of the CH4 ＋ Mx Oy gas-solid reactions was calculated and analyzed using the HSC Chemistry 5.1 thermodynamics software. Furthermore, the effects of temperature on the equilibrium compositions of synthesis gas production process in molten salt （molar ratio is 1 ： 1 of Na2CO3 and K2CO3 ） were analyzed. The results show that theoretically, only ZnO and SnO2 are feasible for this reaction system, synthesis gas concentration increases with the temperature, the appropriate reaction temperature is around 1200K. Base on the calculated results, a 100MW solar energy system can satisfy the energy requirements for producing 5.32kg liquid zinc per second, at the same time the solar energy of 3.6× 10^4kj is transformed to chemical energy.