本文選題：脫硝　切入點(diǎn)：脫硫　出處：《濟(jì)南大學(xué)》2017年碩士論文

【摘要】：粉煤灰是火電廠燃煤鍋爐排放的一種工業(yè)廢渣,是一種人造的火山灰質(zhì)材料。利用粉煤灰作為輔助性膠凝組分生產(chǎn)水泥,是其資源化利用的有效途徑之一。但近年來(lái)火電廠在原有脫硫工藝的基礎(chǔ)上加裝脫硝設(shè)備,致使粉煤灰在建材行業(yè)的利用中出現(xiàn)異常氣味、拌合物含氣量高、膠砂體積膨脹、強(qiáng)度下降等異常現(xiàn)象,限制了粉煤灰在水泥混凝土中的資源化利用。本文針對(duì)以上問(wèn)題采用模擬脫硝脫硫灰的形式,研究了粉煤灰單摻脫硝副產(chǎn)物(NH_4HSO_4)、單摻脫硫副產(chǎn)物(CaSO_4?2H_2O和CaSO_3?0.5H_2O)和復(fù)摻脫硝脫硫副產(chǎn)物(NH_4HSO_4、CaSO_4?2H_2O和CaSO_3?0.5H_2O)對(duì)水泥體系標(biāo)準(zhǔn)稠度需水量、凝結(jié)時(shí)間、安定性以及強(qiáng)度等宏觀性能的影響規(guī)律。利用XRD、SEM-EDS、TG-DSC、水泥水化熱測(cè)定儀以及壓汞儀等測(cè)試手段進(jìn)行機(jī)理分析,得出了脫硝脫硫副產(chǎn)物對(duì)粉煤灰-水泥體系物相組成、微觀形貌、水化產(chǎn)物、水化程度以及孔結(jié)構(gòu)的影響情況。提出了脫硝脫硫粉煤灰的改性方法。研究結(jié)果對(duì)脫硝脫硫粉煤灰的綜合利用以及水泥工業(yè)的節(jié)能減排、可持續(xù)發(fā)展具有巨大的經(jīng)濟(jì)價(jià)值和社會(huì)意義。主要研究結(jié)果如下:(1)當(dāng)脫硝副產(chǎn)物NH_4HSO_4摻量大于1.5 wt.%時(shí),隨其摻量的增加,初凝時(shí)間和終凝時(shí)間明顯延長(zhǎng),而副產(chǎn)物摻量對(duì)水泥需水量及安定性影響較小;當(dāng)摻量大于1.5 wt.%時(shí),體系各齡期抗壓強(qiáng)度和抗折強(qiáng)度隨摻量增加逐漸降低;物相組成中出現(xiàn)重銨礬晶體;副產(chǎn)物導(dǎo)致水泥結(jié)構(gòu)28d時(shí)無(wú)害孔和少害孔數(shù)量減少,多害孔數(shù)量增加,總孔隙率增加;水泥體系初始水化期的放熱速率增加,加速期和衰減期的放熱速率降低,水泥水化3d時(shí)累計(jì)放熱總量明顯增加。(2)脫硫副產(chǎn)物CaSO_4?2H_2O占比越大,水泥初凝時(shí)間和終凝時(shí)間越長(zhǎng);當(dāng)副產(chǎn)物摻量小于2.0 wt.%時(shí),其摻量及CaSO_4?2H_2O和CaSO_3?0.5H_2O的摻加比例對(duì)水泥結(jié)構(gòu)3d、7d抗壓強(qiáng)度影響較小,28d各組的抗壓強(qiáng)度值較空白組高3~7 MPa,而當(dāng)摻量大于2.0 wt.%時(shí),各組各齡期的抗壓強(qiáng)度值降低3~6 MPa;由于CaSO_4?2H_2O的溶解度大于CaSO_3?0.5H_2O,其易與水泥反應(yīng)生成鈣礬石,提高體系的早期強(qiáng)度;副產(chǎn)物CaSO_4?2H_2O對(duì)粉煤灰的激活作用明顯,隨著齡期的延長(zhǎng),體系中的玻璃體相(莫來(lái)石和石英)和Ca(OH)_2的衍射峰值逐漸降低。(3)在脫硫副產(chǎn)物摻量2.0 wt.%條件下,隨著脫硝副產(chǎn)物摻量的增加,水泥結(jié)構(gòu)3d、7d和28d的抗壓強(qiáng)度較空白樣分別降低1~3 MPa、1~5 MPa和1~10 MPa,與單摻脫硫副產(chǎn)物各齡期高于空白樣1~7 MPa形成鮮明對(duì)比;復(fù)摻脫硝脫硫副產(chǎn)物造成水泥硬化結(jié)構(gòu)凝膠數(shù)量減少,有害孔數(shù)量增多,總孔隙率增加,說(shuō)明脫硝副產(chǎn)物對(duì)水泥結(jié)構(gòu)的危害程度遠(yuǎn)大于脫硫副產(chǎn)物;副產(chǎn)物中的CaSO_4?2H_2O占比越高,粉煤灰的水化程度越高,玻璃體相的衍射峰值越低,體系中非蒸發(fā)水含量越高,Ca(OH)_2含量越低。(4)采用預(yù)水化方法處理脫硝脫硫粉煤灰,水泥結(jié)構(gòu)3d、7d和28d的抗壓強(qiáng)度和抗折強(qiáng)度分別提高1%、4%和9%;通過(guò)孔溶液氮含量的測(cè)試結(jié)果可知,處理后的水泥結(jié)構(gòu)1d齡期氮含量降低68%,7d齡期氮含量降低36%,28d之后體系氮含量維持5%左右;由于處理后的粉煤灰可以有效改善粉煤灰-水泥體系的孔結(jié)構(gòu),使得總孔隙率降低2.18%;在耐久性方面,其抗氯離子滲透能力與抗硫酸鹽侵蝕能力得到大大提高。
[Abstract]:Fly ash is an industrial waste power plant coal-fired boiler emissions, is an artificial volcano gray material. As a supplementary cementitious material in cement production using fly ash, is one of the effective ways of resource utilization. But in recent years, based on the original desulfurization power plant installed denitration equipment, resulting in abnormal smell appeared in the use of fly ash in building materials industry, the mixture with high gas content, mortar volume expansion, abnormal strength decline, limiting the resource utilization of fly ash in cement concrete. According to the above problem with simulated denitrification desulfurization ash in the form of fly ash doped denitration side the product (NH_4HSO_4), single mixed desulfurization by-products (CaSO_4? 2H_2O and CaSO_3? 0.5H_2O) and mixed with the denitration desulfurization by-products (NH_4HSO_4, 2H_2O and CaSO_4? CaSO_3? 0.5H_2O) of cement standard consistency water demand, setting time, stability Influence of the macroscopic properties and strength. The use of XRD, SEM-EDS, TG-DSC, this paper analyzes the mechanism of cement hydration heat test methods and determination of mercury injection apparatus, the denitration desulfurization by-products of fly ash and cement phase composition, microstructure, hydration, hydration degree and the influence of hole the structure of the proposed modified method of desulfurization and denitrification of fly ash. The results of energy-saving emission reduction and comprehensive utilization of desulfurization and denitrification of fly ash and cement industry, has great economic value and social significance of sustainable development. The main results are as follows: (1) when the denitration byproducts of NH_4HSO_4 content is more than 1.5 wt.% when, with the increase of its dosage, initial setting and final setting time was prolonged, and the by-product dosage of cement water requirement and stability influence is small; when the content is greater than 1.5 wt.%, the compressive strength of the system in each age and the flexural strength increased with content The amount decreased; heavy crystal phase composition of alum; by-products resulted in a decrease of harmless hole and less harmful pore number of cement structure 28d, and multi hole number increased, total porosity increased; cement initial hydration exothermic rate period increases, accelerated phase and decay phase of the heat release rate decreased, water cement 3D when the total cumulative heat increased significantly. (2) the desulfurization by-product of CaSO_4? 2H_2O the greater the proportion of cement, initial setting and final setting time is long; when the by-product content is less than 2 wt.%, and the content of CaSO_4? 2H_2O and CaSO_3? 0.5H_2O cases of cement mixing ratio of 3D. Effect of 7D is low compressive strength, compressive strength of 28d were higher than those in control group 3~7 value MPa, and when the content is greater than 2 wt.%, the compressive strength of each age decreased 3~6 MPa; because the solubility of 2H_2O CaSO_4? 0.5H_2O, greater than CaSO_3? It is easy to generate ettringite mud water reaction, improve The early strength of the system; the by-product of CaSO_4? 2H_2O activation of fly ash was increased with age, vitreous body in the system phase (mullite and quartz) and Ca (OH) _2 diffraction peak gradually decreased. (3) in the by-product content under the condition of 2 wt.%, with the increase of removal no by-product content, cement structure 3D, compressive strength of 7D and 28d were lower than the control samples of 1~3 MPa, 1~5 MPa and 1~10 MPa, and only mixed desulfurization by-products in each age is higher than that of the blank sample 1~7 MPa contrast; mixing denitration desulfurization by-products caused by the quantity structure of hardened cement gel decreased the number of harmful pores increased, total porosity increased, indicating the denitration byproducts on the degree of harm is far greater than the concrete structure of the desulfurization by-products; by-products in CaSO_4? 2H_2O the higher the proportion, the higher the degree of hydration of fly ash, the lower the diffraction peak phase of vitreous body, in the system of non evaporable water content High Ca (OH) _2 content is low. (4) the pre hydration treatment method of desulfurization and denitrification of fly ash cement structure, 3D, 7d and 28d compressive strength and flexural strength were increased by 1%, 4% and 9%; the test results showed that the nitrogen content of the pore solution, the cement structure of 1D age N content after treatment decreased 68%, the nitrogen content of 7D age decreased 36%, the 28d system after nitrogen content maintained about 5%; the pore structure of fly ash can effectively improve the fly ash and cement, the total porosity decreased by 2.18%; in terms of durability, the chloride ion penetration resistance and sulfate resistance has been improved greatly.

【學(xué)位授予單位】：濟(jì)南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TQ172.1

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