Because fluid-bed aerification furnace is used the atmosphere inside raw material diversification, furnace is complex, layer of fireproof to liner material exists to erode and be destroyed, the service life of fireproof material liner is opposite liner aerification furnace long cycle is stable moving influence is tremendous. Aerification furnace liner is fireproof the choose and carbonadoes making is to matter to success or failure of coal aerification craft crucial technology of material. The article asks to reached failure mechanism to undertake introductory to the sort of fireproof material, function, the research current situation that corrodes commonly used and fireproof material to fluid-bed and alkali resistance undertook summing up, be aimed at characteristic of craft of fluid-bed coal aerification, put forward aerification furnace liner fireproof material chooses the proposal that reachs liner construction to wait, for liner of fluid-bed industry furnace the filtration of fireproof material is reached make provide guidance.
Pressurization fluid-bed coal aerification technology is in recent years as clean coal technology arisen and the new generation that development rises is advanced and large, gas change a technology. Normally the characteristic of coal aerification reaction of high temperature high pressure asks in aerification furnace interior must be added set fireproof material liner. Normally cent is aerification furnace structure 3: Most the layer is; of insulation material layer among the; of fireproof material layer that lining is medium of direct contact high temperature the outerest for stainless steel furnace casing. Besides the crucial technology such as reactor structure and accessory equipment, because temperature, pressure reachs the requirement of the condition such as other reaction operating mode, the choice of material of its reactor liner and the crucial technology that carbonado making also is to matter to craft success or failure. The service life of fireproof material liner is opposite liner aerification furnace long cycle is stable moving influence is tremendous.
Coal aerification craft is planted because of used coal various, character each different, operating mode of the reaction inside fluid-bed aerification furnace is mixed, accompany the atmosphere that high temperature oxidation, vulcanization, hydrogen sulfide, carbonization, chloridize waits to corrode normally, the craft that coal is planted or adds alkali metal activator to tall alkali metal at the same time introduces possibly still alkaline corrode wait for a problem, this a little bit erode the service life that affected fireproof data badly, and move to the safe stability of high temperature device cause undesirable effect. The happening that corrodes inside aerification furnace makes the choice of fireproof material and service life equipment get attention.
1, the sort of fireproof material and failure mechanism
The classified level with fireproof material different according to has different classification. Specific and OK according to chemistry different cent is alkalescent, neutral and basis of; of acidity and fireproof material to differ for goods configuration, cent whether does basis of; of fireproof material and adventitious fireproof material pass fire to finalize the design, cent is firing with did not burn fireproof material; also but according to be able to bear or endure material chemistry composition differs cent is: Silica is able to bear or endure material, aluminous silicate is able to bear or endure material, magnesium is able to bear or endure character material, carbon is compound be able to bear or endure material.
What fireproof material uses operating mode is complex reach abominable sex to decide, differ according to use environment need to put forward different function to ask to fireproof material, include its to fight temperature to damage function of function, heatproof strain crack to reach fight environmental medium aggressivity to be able to wait.
As a result of each its manage turns fireproof material function is put in bigger difference, should join environment of reactor characteristic, work and specific utility, choose appropriate fireproof data. To fluid-bed aerification furnace, the attaint of fireproof material basically divides liner to be eroded for chemistry, heat is eroded, machinery erodes 3 kinds big. Chemistry erodes what can cause function of fireproof material composition to reduce, increase then thermodynamic erode the influence that reachs machinery to erode pair of material wear-resisting performance.
The choice of material needs to combine craft characteristic adequately. The run that attention requires when normally material is chosen changes index to include compression to fight fold intensity, wear-resisting and thermal shock stability, heavy burn a line to change rate. The material that leaves an alternative when reaction operating mode, be like pouring makings did not amount to place to require firing temperature, criterion intensity can be reduced greatly, need to assure what to choose fireproof material to have better strength below working temperature above all, the intensity of the material when when perhaps beginning drying-out, carbonadoing to what achieve material to pledge firing temperature moves with assuring operating mode is higher. Additional, fireproof material reachs drying-out process in the construction that make, installation medium unreasonable also can bring about be able to bear or endure the attaint of material. Accordingly, must ensure manufacturer asks strictly in the construction process that make to undertake construction according to the design, make sure whole process is contented at the same time be able to bear or endure the material construction requirement that timber production manufacturer raises. Ensure the water that contains in material divides transgression of vapor of complete translate into, the exceeds material because of the vapor pressure in fireproof material tensile strength after avoiding furnace ignition to move causes liner then statified, break down, bring about furnace liner to collapse fall.
2, fluid-bed reactor and alkali resistance are corroded be able to bear or endure material research
2.1 fluid-bed reactor uses the current situation of fireproof material
Normally fluid-bed can divide by action with fireproof material liner it is 3 kinds: Insulation material of; of fireproof material of wear-resisting material; . The fireproof data that existing fluid-bed uses includes: Phosphate is able to bear or endure material; carborundum is able to bear or endure material; corundum is able to bear or endure material; nitrogen changes silicon to combine carborundum product to wait.
Phosphatic brick applies to 1200 ～ limits of 1600 ℃ temperature, do not bake bricks for what heat treatment of 500 ℃ low temperature gets, already applied in cement kiln old, boiler liner also uses inchoate circular fluid-bed this material. But inside the moving temperature limits in circular fluid-bed boiler (850 ～ 900 ℃ ) , phosphate is able to bear or endure material performance is not steady, wearability is poor, but because of price advantage, its are inchoate more application is had in fluid-bed.
Carborundum is able to bear or endure material has exceedingly good wear-resisting and thermal shock stability. But to coal aerification craft, suffer because of oxidisability atmosphere is being taken to bring about its to use slightly inside reactor be restricted. The report points out, the United States is forbidden carborundum is chosen to be able to bear or endure in circular fluid-bed boiler material, and the use that higher cost also restricted carborundum.
Siliceous aluminous simple fireproof stuff (Al? O3-SiO? Department) , is basic and chemical composition Al? O3, SiO? . This department is able to bear or endure the application in material is more reach corundum for Molaishi fireproof material. Because Mo Laishi is fireproof degree tall, fight it is creep, good to fight chemical aggressivity, loading bate temperature is tall, heatproof better, bulk stabilizes shake function performance is good and insulating property is strong, make good advanced and fireproof material. But chemical composition of Molaishi is not stable, include 2Al? O3·SiO? Reach 3Al? O3·2SiO? Two kinds of forms. Corundum is fireproof in material, al? O3 content prep above 90% and advocate is brilliant photograph α-Al? O3.
Corundum has thermodynamic strength sex of good, heatproof shake reachs tall, chemical stability fight abrasiveness capability of action of good, counteractive reducer is strong wait for function, because this serves as the important raw material of advanced and fireproof material.
Integrated the consideration of each respect element such as afore-mentioned material function and price, coal aerification furnace chooses corundum to regard liner as fireproof material normally, the variety that uses normally has He Zonggang of Bai Gangyu, tall aluminous corundum jade.
To coal aerification furnace, choose be able to bear or endure what material composition reachs design construction is different bring about be able to bear or endure of material liner fight coal ash to erode ability each different. Coal ash is right of fireproof material erode mechanism namely coal ash is mineral with fireproof data reaction, erodent process. Consider to make clear, coal ash is able to bear or endure to tall aluminium of material erode the strongest, carborundum is able to bear or endure material take second place, fireproof material fights corundum erode ability the strongest.
2.2 different and fireproof material are fought alkaline corrode characteristic research
Each atmosphere is corroded in aerification furnace in, alkaline erode to be able to bear or endure the destruction of material liner action especially strong. The alkali metal inside furnace evaporates, agglomeration comes firebrick lining, especially aperture place, amid rich collect, permeate, bring about bricky line to corrode, craze, be able to bear or endure material liner is sufferred destroy.
Current, be opposite in alkali metal of fireproof material corrode a respect, began a large number of works domestic and internationally. Blast furnace worker made fireproof material fight level of state of method of alkaline function experiment, its are fought high with low porosity alkalescent for the target, developed Xu Guotao of; of small stomatic product to wait to be opposite through inspecting alkali metal of different and fireproof material caustic, those who study fireproof material falls in different condition is alkaline erode a process, put forward to be able to bear or endure material improves countermeasure; Li Wei to wait to heat up what studied silicon aluminium fastens fireproof material below the reproducibility conditions to corrode behavior in carbon, the corrosion resistance that discovers tall aluminous brick can be best, and the accretion of alkali metal aggravate of fireproof material erode, additive adds a quantity to increase erode aggravate; Zhou Shizhuo to wait studied what material and carbolic material expect to all sorts of silicon aluminium are able to bear or endure character fight alkaline aggressivity can, discover alkali metal to be able to bear or endure character to silicon aluminium of material because formed high volume of nepheline of leucite, Potassium to expand,eroding is material, caused bricky line volume thereby expand, reach corundum is able to bear or endure character of material fight height of alkaline caustic the can strongest; to wait made an on-the-spot investigation to contain alkaline coal ash to reach aggressivity in the wetability of different firebrick surface, discover what corundum brick gets to erode the weakest;Stjernberg to wait studied Molaishi / corundum is able to bear or endure material and the reaction that contain alkaline material, discover alkali metal and firebrick reaction made nepheline and leucite appearance, of appearance of this somes of substance generate bring about the journey inside the brick certain volume expands, quickened fireproof material then mar. It is certain to contain fireproof stuff to cause damage, guide thereby ” of generation “ alkaline splitting decomposition. In addition, contain alkaline material to be able to form felt content to damage then fireproof material, especially easy form sulfur - alkaline compound, attaint is able to bear or endure the felt structure of material. Consider to make clear, the alkaline corrode under 900 ℃ contains alkaline material together for fireproof material immediate reaction is caused, and below high temperature because will contain potassium compound,eroding is reductive into made potassium steam, produce migratory oxidation reaction to cause then.
Those who contain alkaline operating mode to issue commonly used and fireproof data face to fight below alkaline caustic have detailed introduction:
(1) silicon aluminium fastens fireproof material
The basic and chemical composition that Al2O3-SiO2 is fireproof material is alumina and 2 oxidation silicon, the discretion of content of according to alumina.
Using Al2O3-SiO2 is fireproof material, the chemical reaction that contains alkaline compound to happen to it is as follows:
A? S? + 16SiO? + 3K? O→3KAS? (Orthoclase)
A? S? + 10SiO? + 3K? O→3KAS? (Leucite)
2A? S? + 8SiO? + 6K? O→6KAS? (Square Potassium nepheline)
11Al? O? + K? O+Na? O→(K·Na)A11(β corundum)
K? SO? ·2CaSO? + H? 0→2CaSO? ·K? SO? ·H? O(Potassium gesso)
2CaSO? + K? SO? →2CaSO? ·K? SO? (Anhydrous Potassium gesso)
Alkali metal is qualitative to Al2O3-SiO2 of fireproof material because formed nepheline of leucite, Potassium, β- ,eroding is corundum, its generate bring about be able to bear or endure material liner volume happens expand, brought about the happening of phenomenon of alkaline splitting decomposition finally. Reaction child depends on the content of the Al2O3 in alkaline chroma and fireproof material, SiO2. Alkali metal pledges to all sorts of silicon aluminium fireproof material expands destructive degree each are not identical.
Tall aluminous brick (Mo Laishi composition) fireproof material is the poorest, damaged expands most serious. Alkali metal is the same as Molaishi to react, in 700 ～ 110 ℃ generate nepheline, those who contain alkaline content photograph build meeting generation 20% ～ the bulk of 25% expands, bring about material to mar.
It is better that corundum pledges fireproof material fights alkali metal function, bulk change is the least. Alkaline erodent mechanism is: Crystal boundary material and contain alkaline material to produced reaction to produce new material, and this material produced certain volume to expand, bring about corundum to be able to bear or endure the disintegrate of material test block, namely the process that the K2O below constant temperature, pressure and Al2O3 fashion solid solution Potassium, chemical reaction is as follows:
1/11K? O(S)+Al? O? (S)→1/11(K? O·Al? O? ) (S)
Additional, alkali metal is right the corrodes function to accept form of time of specific response temperature, atmosphere, reaction and alkali metal existence influence of fireproof material. Different aerification craft is choosing aerification furnace liner when fireproof material, should combine oneself craft characteristic and condition of craft of use place, specific inside aerification furnace response (atmosphere, temperature) , K configuration those who wait is different and choose different fireproof material. But fall in high temperature and chroma of tall alkali metal, nonexistent the silicon aluminium that defies alkali metal is eroded absolutely is qualitative fireproof material. Accordingly, accumulate serious blast furnace circularly to alkali metal, bottom should not use tall aluminous liner, additional, air hole is spent is one of crucial factors that affect fireproof material to fight alkali metal function.
(2) contains chromic fireproof material
Magnesian chromic qualitative, chromic corundum is fireproof material is fireproof degree tall, high temperature strength is great, heatproof shake sex is admirable. Because its fight alkaline function goodly to reach admirable high temperature resistant characteristic, magnesian chromic simple fireproof stuff uses as for a long time alkaline reclaim furnace lining is able to bear or endure material. Contain the Cr in chromic fireproof material? O? , especially the Cr in matrix? O? Be helpful for increasing material density and strength of the union that heat up voice, reduce porosity, improvement fights broken bits aggressivity. But Cr? O? As easy below oxidation atmosphere as chromic mine with alkali metal oxide (K? O, Na? O) reaction generates the 6 price chromate of low melting point, its react form is as follows:
2(Cr? O? ) + O? + R? O→4(R? CrO? ) (R-K, Na)
The happening of this reaction, destroyed Cr not only on one hand? O? With the structure of chromic mine, and does formation low frit content return the; inside meeting infiltration brick on the other hand chromate R? CrO? It is compound of a kind of weak oxidisability, chemical stability is taller, 6 price chromium is poisonous can cause cancer, consider to make clear in great quantities: Ulcer of a few skins and respiratory tract disease all are concerned with Cr6+ , and the pollution that can cause to the environment is had durative. As the buildup of environmental protection consciousness, already mentioned ” of processing “ chromic social effects of pollution the order of the day.
(3) aluminium acerbity calcium fastens fireproof material
CaO-Al? O? Two important compound include in binary system, namely 6 aluminous acid are 2 aluminous acerbity calcium, calcic. Because of good water ability of hardening capacity, decarbonization reachs high temperature performance characteristics, apply in the industry such as building materials, metallurgy, national defence extensive.
Are 6 aluminous acid calcic (CaAl? ? O? ? Or CaO·6Al? O? , is logogram CA? , mineral name: ) of black aluminous calcic rock, because of relatively the manage of beautiful turns performance in recent years times get attention. Are its in CaO-Al? O? In binary system, fight to hydrate sex best, melting point (highest about 1830 ℃ decompose melt) .
CA? Crystal anisotropy grows, can form 6 an appearance of shape crystal form, this brilliant have small hole structure, and agglomeration is restrained in internal energy of constant temperature limits, the apparent pore rate that carries data is basic and fixed, lower coefficient of thermal conductivity. Be worth what carry is, CA? With Al? O? Have wonderful comfortable match a gender, both because make the same score soaking coefficient of expansion to be close to very, can make deserving to compare and won't be caused arbitrarily expand break match. In the meantime, as a result of CA? Melting point is high, good in the stability below high temperature reducing atmosphere, it is better to be had in alkalescent environment fight erode ability. Prospect of progress of 6 aluminous acerbity calcic material is good.
Below high temperature condition, corundum, CA? Metropolis with K? O reaction. Corundum and oxidation Potassium reaction generate β- corundum, companion expands as larger volume, this is one of main reasons that cause fireproof liner to destroy. But CA? crystal structure and β-Al? O? Crystal structure is similar, embed Ca2+ in layer shape alumina, alkali metal ion can be absorbed between the layer, and volume won't happen apparent change; additional, CA? bulk density (3.38g/cm? ) the bulk density with KA11 (3.37g/cm? ) close, become so CA? By alkaline when eroding, the fireproof data phase with other is compared, its bulk stability is taller.
(4) magnalium pointed spar fastens fireproof material
Magnalium pointed spar (MgO·Al? O? Or MgAl? O? , is logogram is MA) MgO-Al? O? Only stability is put in compound in binary system. Magnalium pointed spar is the octahedral structure of isotropy, be united in wedlock with electrovalent bond between Al-O, Mg-O, its are electrostatic key intensity is same, the structure is stable. Structure of this kinds of crystal made sure MA is able to bear or endure the thermal shock stability with superior material and wear-resisting function, and fall in oxidation reducing atmosphere, to the SO of free? / SO? Reach K? O/Na? O is had relatively of beautiful fight aggressivity, accordingly, MA applies in fireproof data industry extensive. Additional, melting point of magnalium pointed spar is high (2135 ℃ ) , coefficient of thermal conductivity is low, hot coefficient of expansion small, intensity tall, hardness is big, fight concussion, fight alkaline erode ability strong, and very stable also to the action of the oxide of iron.
(5) composite material
In view of CA? It is better to reach MA to all be had fight alkaline corrode function, and CA? The close of hot coefficient of expansion that reachs MA, consistence is good, OK and aleatoric scale cooperates, nonexistent expand break compound a problem. Accordingly, can consider two kinds of material compound use, already developed a CA at present? - MA is compound light qualitative aggregate, have good thermal shock stability via considering to make clear its, be able to bear or endure function of aggressivity, wear-resisting reachs the good aggressivity that fight broken bits.
(6) aluminous charcoal fastens fireproof material
Aluminous charcoal fastens fireproof material to apply on blast furnace more, if be being put in the molten iron pretreatment of alkaline corrode,reductive furnace is having furnace, melt to apply or apply foreground potentially. Among them SiAlON(carborundum kind) the crucial and fireproof material that combines corundum material to become large blast furnace to go up character. Below reducing atmosphere, contain a lot ofwhat the blast furnace slag of alkali metal combines corundum brick to SiAlON to erode speed lesser, its erode mechanism to generate potassium nepheline for SiAlON and alkaline steam reaction, the reaction such as natrium of the in generating; corundum grain and grey broken bits oxidation ferrous that shared silicate glass photograph, oxidation and oxidation Potassium makes iron aluminium pointed spar and a few acicular β- alumina.
But SiC is used below oxidisability operating mode, does SiC oxidation become SiO? , can generate alkaline silicate, produce photograph of high temperature felt, with synchronism of exterior layer reaction, easy form the layer that hang broken bits. This on one hand may process of slow down alkaline corrode, but the existence of photograph of felt of this high temperature is met at the same time conglutinate is fireproof material and grey broken bits, the likelihood generates nepheline etc low temperature further in all frit content, cause matrix fragile change mar.
3, liner of fluid-bed aerification furnace is able to bear or endure the proposal of material
(Temperature of medium of the job inside furnace of aerification of 1) union fluid-bed is tall, caustic reach internal matter by force to flow to erode to aerification furnace liner serious characteristic, need to have in aerification lining be able to bear or endure erode, fight corrode, heatproof shake function and certain hot bulk stability. In the meantime, coal aerification furnace is fireproof henceforth of material liner choose will more lay particular stress on at sex of its economy environmental protection, and convenient, service life repairs requirement construction longlier, easily etc.
(Furnace of aerification of 2) industry dimensions is chosen suit be able to bear or endure material liner, need to integrate respective craft characteristic and adoption raw material character, strengthen the attention that to its manage turns performance, like compression intensity, fight fold function of intensity, wear-resisting, corrosion resistance and thermal shock stability to wait, whether does this somes of function amount to mark, the lasting periodic stability that can affect aerification furnace likewise moves. The proposal builds relevant check mark to allow, undertake detecting in the round to the function of fireproof material, ask relevant professional technology personnel and the expert that have practice experience relevant detect undertake assessment, ensure relevant manage changes index to satisfy technology design to ask; is additional, whether do the aptitude that chooses manufacturing construction manufacturer and ability satisfy craft to ask the function of liner of fireproof to aerification furnace also material and service life impact are bigger.
(3) aerification furnace should strict according to contented be able to bear or endure material performance characteristics asks litre drop in temperature the curve undertakes drying-out is reached drop in temperature processing, and avoid as far as possible in move urgent jockey, decrease open stay a time, avoid to be able to bear or endure material generation stress is fatigue, bring about liner craze. Additional, need to arrange scheduled maintenance, discover craze is repaired in time.
Long-term to blast furnace stability runs the long life of blast furnace crucible the action with a crucial move, in a lot of element of damaged of blast furnace crucible, of alkali metal eroding is a main influencing factor, this is in domestic and international many blast furnace damaged had gotten sufficient test and verify in investigation. In crucible, alkali metal basically passes the fireproof material such as pair of charcoal bricks to undertake osmotic causing erodent, serious when form inside blast furnace fragile change a layer. Fight the fireproof stuff with alkaline good performance to choose, must choose a kind of method to undertake evaluating to fireproof material, undertake contrasting analytic through cogent and valid data.
Fight to fireproof material at present alkalescent determining method, in steel group is fireproof material academy drafted level of GB/T 14983—2008 state, namely " fireproof material fights basic test method " . It is from the cube that a 20mm cuts to control bulk inside firebrick, undertake burnish to each faces and measure size with vernier calipers, put charcoal, potassium carbonate and sample into crucible next, through crucible the lid has link, 30h of 1100 ℃ heat preservation warms up after nitrogen is being connected inside past furnace, the macroscopical form appearance of firebrick and microcosmic form appearance observe after the experiment ends, determine the ratio of compressive strength change of firebrick. But this method puts in the following defect: (The experiment method in 1) GB is to pass what the reaction of alkaline steam and fireproof material evaluates fireproof data to fight alkali metal function, but pass thermodynamic analysis knowable, in blast furnace crucible, alkaline steam can not produce reaction with fireproof material directly, diffuse however after fireproof data is inside be reacted form new look by the ability after liquefaction and fireproof material, real case is severe inside the method of GB and blast furnace not agree with; (After 2) experiment ends, in GB lead from change of macroscopical form appearance, microcosmic form appearance, compressive strength merely undertake token, token resort is too little, cannot evaluate fireproof material quite integratedly to fight alkalescent actor of low quality, should raise quality change ratio, bulk change rate, the step such as EDS analysis will evaluate fireproof material to fight of low quality of alkaline function actor in the round.
Before the viewpoint thinks the alkali metal inside blast furnace is right of fireproof material eroding is to pass alkali metal gas and fireproof data reaction to undertake, we are accordingly right the reaction of K steam and charcoal brick undertook thermodynamic analysis. Steam of the K inside furnace reacts inside furnace K2O, K2CO3
Steam reacts inside furnace K2O, K2CO3. ΔG2 ＝ - 213800+152.16T+RTln(1/((Pk/Pθ)2×(Pco/Pθ)3) , when T ＝ when 750 ℃ , cent pressing is the critical K steam that type reacts on 52.7KPa and 16.2KPa, this is impossible to happen in actual blast furnace, because this K steam won't be direct,with fireproof material reaction destroys fireproof data. The basis overcomes Lao Peilong - the liquefacient condition that overcomes steam of Potassium of computation of Lao Xiusi equation to fall in high-pressured condition, knowable Potassium steam falls in condition of crucible high pressure, can issueing liquefaction under the condition of 932 ℃ . From this we undertake thermodynamic analysis to the reaction of liquid state Potassium and fireproof material again, when temperature is 750 ℃ , the response that makes nepheline of leucite, Potassium wait to liquid state Potassium and fireproof material, their ΔG ＜ 0, show this reaction can happen. Because this can conclude, alkali metal is become by reductive form inside furnace alkali metal steam, alkaline steam won't produce reaction with fireproof material directly, pass line of aperture infiltration brick however, in blast furnace crucible cooling action falls, alkaline steam begins liquefaction not to decide rich part, after forming new look with the material such as CO next, begin to expand.
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