Study On The Preparation And Gasification Characteristics Of Wheat Straw-coal Slurry

Wheat straw, as the agricultural waste, contains plenty of alkali metal compounds. Directlyburning of waste straw has caused serious air pollution. But if blend the shattered wheat straw intocoal water slurry(CWS), it can not only improve the reactivity of CWS, but also can reducepollutant emission like NOx、SOxand CO2. Wheat straw is characterized with high water content,rich fiber and not easily broken, which is detrimental to the high performance of CWS. In thispaper, wheat straw was carbonized at low-temperature and wheat straw-CWS(WSCWS) wasprepared with meager-lean coal, which is easy to prepare high quality CWS. The effect of wheatstraw on the slurrying and gasification characteristics of WSCWS was studied.Through the basic properties of wheat straw fore and after carbonization, wheat straw canoccur fast pyrolysis below400℃. The moisture, volatile and oxygenic groups of carbonizedwheat straw decrease, but the porosity increase. Meanwhile the passage rate of carbonized wheatstraw is increased by3.67times than the raw sample.The preparation experiments of slurry were carried out to compare the slurryingcharacteristics differences of WSCWS and CWS. The results show that after adding wheat strawthe slurry concentration and liquidity become worse, but stability is better. With the wheat strawaddition increased, the flow pattern of slurry changes from yield dilatancy fluid to Bingham plasticfluid. The slurry concentration and liquidity declines significantly, but stability is improved.With the same addition, carbonized WSCWS exhibits the higher liquidity and stability. The slurryconcentration is increased7.12%than fore carbonization. The carbonization temperature has a bigeffect on slurrying characteristics of WSCWS. When slurry concentration is60%, the addition ofwheat straw can increase from6.67%to40%by carbonization. But the carbonization time has nosignificant impact on slurrying characteristics.Finally, the combustion and gasification characteristics of CWS and WSCWS fore and aftercarbonization were studied. Due to the high volatility of wheat straw, the combustion activeenergy of WSCWS can be reduced by39.75%. So the combustion characteristic temperatures ofWSCWS are lower. After adding wheat straw, gasification reactivity and carbon conversion ratioare improved. Compared with CWS char, there are plentiful cavity construction and alkalinecompounds in the WSCWS char, which can weaken the bond strengthen of C-C at char surfaceand provide more active site to improve better catalytic activity. There are more inorganic alkalimetals compounds remained in carbonized wheat straw, so the carbonized WSCWS char showshigher gasification activity.