白云石催化松木燃料棒水蒸气气化试验

Experiment on Steam Gasification of Pine Fuel Rods with Dolomite Catalyst

以松木燃料棒为试验对象,水蒸气为气化剂,在反应器底部装载定量的白云石作为催化床,通过考察气相组分变化,以及焦油的傅里叶变换红外光谱变化,综合分析白云石催化随温度变化的规律。试验表明:煅烧后的白云石促进提高气化气中氢气含量,相比无催化剂添加,H_2体积分数在800℃时涨幅较大,由32.32%升高至40.11%;当温度大于850℃,由于白云石催化裂解焦油速率随温度加快,以及碳酸盐自身分解加剧,造成CO_2体积分数增大;白云石能够促使碳氢化合物向小分子H_2、CO_2和CO转化,且随温度升高而加剧。白云石促进脂肪烃的碳链断裂、芳香烃开环反应、脱羟反应、脱羧反应、三键断裂反应,以及羟基和醚链的氧化等,但羧基脱除速率随温度升高逐步大于羟基及醚氧化为羧基的速率,使羧基含量先增加后下降。

Using homemade pine fuel rods as the experimental object, the influence of temperature on dolomite catalytic steam gasification was studied. The results showed that the calcined dolomite can cause long carbon chain cracked, which was conducive to the production of radical hydrogen ion, and helpful to generate hydrogen. Compared with no added catalyst, the volume fraction of H2 was increased from 31.91% to 38.82% at 750℃, increased from 32.32% to 40.11% at 800℃ and increased from 46.01% to 48.16% at 850℃. When temperature was less than 850℃, the volume fraction of CO was reduced due to that the oxidation reaction of carbon monoxide was more dominant than other gasification reaction, and calcined dolomite was easy to absorb CO2. When the gasification temperature was more than 850℃, because the rate of dolomite catalytic cracking of tar was increased, and the decomposition of carbonates was strengthened with increase of temperature, the rate of increase of CO2 volume fraction was higher than the increase of H2 and CO volume fractions, which caused the reduction of H2 and CO volume fractions （compared with no catalyst added）, but the volume fraction of CO was increased. Dolomite catalyst can promote the gradual fracture of the carbon chain of hydrocarbons and make them to be small molecule, such as H2, CO2, CO, etc., and this process was severer with temperature increasing. Dolomite was beneficial to the carbon chain scission reaction, ring opening reaction, decarboxylation reaction, decarboxylation and triple bond cleavage reactions of aromatic hydrocarbons and aliphatic. When temperature was over 850℃, hydrocarbon chain scission and ring opening reaction with the dolomite catalyzed were increased, making its end chain hydroxylation and gradually formed with terminal methyl dehydration condensation ether, and that rate was higher than the rate of oxidation and removal of hydroxyl and ether chains with temperature increasing. Because under the condition of steam atmosphere, the removal rate of carboxyl group was increased with the increase of temperature, and it was faster than the rate of oxidation of hydroxyl and ether chains to produce carboxyl groups, which caused the integral area of the characteristic peak of carboxyl group increased first and then decreased.