我國(guó)每年林業(yè)廢棄物和農(nóng)業(yè)生產(chǎn)剩余物質(zhì)產(chǎn)量高達(dá)7億t，如何有效利用這一巨大資源，已成為擺在科研工作者面前的重要課題。生物質(zhì)氣化技術(shù)改變了直接燃燒生物質(zhì)的利用方式，提高了廢棄生物質(zhì)的能源品位，對(duì)節(jié)約常規(guī)能源、降低環(huán)境污染、保護(hù)生態(tài)環(huán)境具有重要意義。
Every year in our country forestry waste and surplus of agricultural production material production up to 700 million t, how to effectively utilize the huge resources, has become an important topic in front of scientific research workers. Biomass gasification technology changed the way direct combustion biomass utilization, improve the grade of waste biomass energy, to save conventional energy, reduce environmental pollution, protect the ecological environment is of great significance.
下吸式固定床氣化爐由于具有結(jié)構(gòu)簡(jiǎn)單，易于操作，產(chǎn)出氣焦油含量低等優(yōu)點(diǎn)已經(jīng)得到了廣泛的應(yīng)用。生物質(zhì)氣化過程是一個(gè)復(fù)雜的熱化學(xué)反應(yīng)過程，生物質(zhì)氣化爐各部位結(jié)構(gòu)尺寸將極大地影響氣化爐的熱效率、產(chǎn)氣成分和產(chǎn)氣品質(zhì),故設(shè)計(jì)合理的生物質(zhì)氣化爐是有效利用生物質(zhì)能的關(guān)鍵。
Suction under the fixed bed gasifier with simple structure, easy to operate, the output gas low tar content advantages has been widely used. Biomass gasification process is a complex thermal chemical reaction process, each part of the biomass gasifier structure size will greatly affect the thermal efficiency of gasifier, gas composition and gas quality, so the reasonable design of biomass gasifier is the key to effective utilization of biomass energy.
作為氣化劑的空氣從氣化爐側(cè)壁空氣噴嘴吹入，其產(chǎn)出氣的流動(dòng)方向與物料下落的方向一致，故下吸式氣化爐也稱為順流式氣化爐。吹入的空氣與物料混合燃燒，這一區(qū)域稱為氧化區(qū)，溫度約為900～1200℃，產(chǎn)生的熱量用于支持熱解區(qū)裂解反應(yīng)和還原區(qū)還原反應(yīng)的進(jìn)行；氧化區(qū)的上部為熱解區(qū)，溫度約為300～700℃，在這一區(qū)域，生物質(zhì)中的揮發(fā)分（裂解氣、焦油以及水分）分離出來；熱解區(qū)的上部為干燥區(qū)，物料在此區(qū)域被預(yù)熱；在氧化區(qū)的下部為還原區(qū)，氧化區(qū)產(chǎn)生的CO2和碳、水蒸氣在這一區(qū)域進(jìn)行還原反應(yīng)，同時(shí)殘余的焦油在此區(qū)域發(fā)生裂解反應(yīng)，產(chǎn)生以CO和H2為主的產(chǎn)出氣，這一區(qū)域的溫度約為700～900℃。由于來自熱解區(qū)富含焦油的氣體須經(jīng)過高溫氧化區(qū)和以熾熱焦炭為主的還原區(qū)，氣體中的焦油在高溫下被裂解，從而使產(chǎn)出氣中的焦油大為減少。
As the gasification agent of air blowing in from the gasifier wall air nozzle, the whereabouts of the output direction of gas flow and material in the same direction, so the suction under gasifier is also referred to as forward gasifier. Blow into the air and material mixed burning, an area known as the oxidation zone, the temperature is about 900 ~ 1200 ℃, the heat generated by the support area pyrolytic cracking reaction and reduction of area reduction reaction; Oxidation zone of the pyrolysis zone, the temperature is about 300 ~ 700 ℃, in the area, the biomass of volatile (cracking gas, tar, and moisture) isolated; Pyrolysis of upside for arid region, the material in this area is hot; At the bottom of the oxidation zone to reduction zone, area of CO2 and carbon oxide, water vapor in the region to carry on the reduction reaction, and the tar cracking reaction in this area, the residual gas output is given priority to with CO and H2, the temperature of this area is about 700 ~ 900 ℃. Area rich in tar from pyrolysis gas after high temperature oxidation zone and reduction zone, mainly for the hot coke tar cracking under high temperature in the gas, which has greatly reduced gas output in the tar.
由于生物質(zhì)物料的堆比重、粒度相差較大，這將明顯影響物料在爐內(nèi)的駐留時(shí)間，這就要求氣化爐因物料不同而選用差別較大的氣化強(qiáng)度。對(duì)于堆比重較小或粒度較小的物料，其爐內(nèi)駐留時(shí)間短，氣化強(qiáng)度應(yīng)相應(yīng)減??；反之，應(yīng)增大氣化強(qiáng)度。一般氣化強(qiáng)度推薦值為500～2000kg/（h·m2）。
As a result of the biomass material bulk density, particle size is large, it will significantly influence the dwell time of the material in the furnace, which requires a greater difference between gasifier with different materials to choose gasification intensity. For small bulk density or smaller particle size material, the furnace resides within short time, gasification intensity should be reduced accordingly; On the other hand, should increase the intensity of gasification. General gasification intensity recommended value for the 500 ~ 2000 kg/h · m2).
劃詞
盡管下吸式氣化爐產(chǎn)出氣中焦油含量很少，但根據(jù)產(chǎn)出氣的不同應(yīng)用場(chǎng)合，還應(yīng)當(dāng)配置不同的除焦油設(shè)備以及除塵、除濕設(shè)備以進(jìn)一步提高產(chǎn)出氣的品質(zhì)。
Although the little suction gasifier tar content in the gas output, but according to the different applications of gas output, should also configure different except the tar and dust removal equipment, dehumidification equipment to further improve the quality of the output gas.
