Experiment On Microwave Pyrolysis And Drying Of Seaweed Biomass

Biomass is the fourth largest energy in the world, followed by coal, oil and gas.Compared with fossil energy, biomass releases a litter waste discharge, showing theincomparable superiority.Biomass resources include wood and wood wastes, energy crops,aquatic plants, agricultural crops and their waste by-products, municipal wastes. Seaweedbiomass live in the sea, not occupy area land. Its resources development has great potential. Inparticular, China is surrounded by wide coastal areas and territorial seas. If those richseaweeds sources are explored efficiently and put into clean and proper use, they maycontribute a lot to the future of our country in the competition of the worldwide energy usage,both theoretically and industrially. The research on this seaweed biomass is still relativelysmall around world, which is a novel topic. In this paper, the thermochemical conversionprocesses （microwave pyrolysis） and drying of seaweed were studied using a systematicexperimental and theoretical method.Through the experiment of seaweed by microwave pyrolysis, study algal pyrolysischaracteristics.The result showed, the cracking process of the algae can be divided into threestages, dehydration and drying stage, fast pyrolysis stage and slow pyrolysis stage. Comparedthe terrestrial biomass, the conditions of microwave pyrolysis of seaweed were easier tosatisfy.This paper investigated the different conditions （different power, atmosphere, weightof materials and different moisture）, the results showed, the greater microwave power,themore rapidly of seaweed heating and the higher the final pyrolysis temperature can beachieved; The overall trend is that the conversion rate of the algae increases, the solid residuereduces and the amount of gas and liquid products increase as the microwave power increases.Both N2and CO₂atmosphere, CO₂is beneficial to algae preparation of bio-oil and coke; itcan play a catalytic role. The moderate weight and moisture content were conducive to algaemicrowave pyrolysis.By adding different catalysts, the influence of the different additives on the seaweedmicrowave cracking was studied. Mainly by activated carbon, H₃PO₄, NaOH, MgCl₂, MgO asthe object of research, the microwave cracking microalgae experiment, compare these5kindsof catalyst for the influence of seaweed microwave cracking. The results indicated that theactivated carbon, acid, alkali, metal oxides and salt for the catalyst in microalgae can beprepared by microwave cracking for biological oil and coke. Due to its different molecularstructure and properties, the influence of the product is also different. The rate of liquidproduction is very low. For the five inorganic additives, whether they be acid/alkaline or neutral, soluble in water or insoluble in water, all can significantly increase the rate of solidproduct production, significantly reduce the rate of gas production. Additives on the yield ofliquid influence are not significant. And when add H₃PO₄/MgCl₂, the rate of liquidproduction increase, when NaOH the yield decreased.In the fourth chapter, the seaweed constant temperature drying experiment wasconducted. The characteristics of seaweed dry process were examined, under conditions ofdifferent quality/different moisture content or different temperature. The seaweed dryingprocess was also analyzed in theory. The results show that, algae drying process were dividedinto three stages, namely, short of warming period, constant speed dry section and falling ratedrying section. In the warming section, drying curve down on a parabola and drying rateincrease gradually from scratch; In the constant speed drying stages, the slope of each point ofdrying curve is equal and the corresponding drying rate are equal too; In falling rate dryingsection, dry curre declined obviously, and drying rate decreases. Until the curve close to level,drying rate tend to zero. Drying time increased with moisture content. The greater themoisture content, the greater the drying rate, but drying time is longer. For the same moisturecontent of seaweed, it can get the best drying temperature or the drying temperature rangethrough the drying experiment. The seaweed drying process mainly includes preheating stage,constant speed stage, slow down stage and balance stage.With seaweed was gradually heat,temperature and drying rate increased.When began to enter into the evaporation stage, the freewater in seaweed all was off. Then the evaporation process begins to come to internal, thedrying rate was reduced, and the absorb heat temperature was rising. At this time, the seaweedmaterials can be divided into three parts: dry area, evaporation area and wet area. Finally,when the moisture inside the seaweed and water in the medium of the surrounding air come towater phase equilibrium, drying rate is zero and dry process is over.At last, the paper discussed the full text and the future research work was forecasted.