CN101139175A - Cement presintering production method and system - Google Patents

Abstract

The present invention relates to a new cement manufacturing technology. By enhancing the temperature of the kiln feed of a rotary kiln, the inefficient heat transfer process remaining in the cement rotary kiln is greatly reduced or eliminated and the thermal bottle-neck problem in the cement calcinations is solved so as to realize the fast firing of the fine particles and highly efficient cooling of the clinkers, and the anti-skinning materials, high temperature resistant materials and insulating materials are adopted and the aspect ratio, rotation speed and slope of the rotary kiln are changed so as to realize the present invention, thus generating the very obvious comprehensive effects of enhancing the output of the cements, lowering the burning heat consumption and the grinding pow consumption and enhancing the clinker quality.

Description

A kind of cement presintering production method and system thereof

Technical field:

The present invention relates to field of cement production, be specifically related to a kind of cement output that significantly improves, obviously reduce the novel concrete manufacture method of burning till hear rate.

Background technology:

During cement was made, traditional rotary kiln sprayed into fuel from kiln hood, and the kiln tail is sent into raw material, and the kiln material by kiln gas and countercurrent flow carries out burning till of heat exchange realization cement.Because the material in the kiln is in stacking states; grog forms needs a large amount of heats again; this just makes that the heat transfer efficiency of rotary kiln is very low; the temperature-rise period of kiln material is very slow; the output of cement rotary kiln is very low; the exhausted air quantity of unit output and kiln cylindrical shell are all very big, and the heat of being taken out of by waste gas and also very by the heat lost by radiation of kiln drum surface has caused the low yield and the high energy consumption of manufacture of cement more.

Modern cement nsp kiln utilizes preheater that material is carried out high speed suspension heat transfer, carries out secondary combustion in decomposing furnace, provides 90% carbonate decomposition required heat energy, thereby has significantly improved the efficient of manufacture of cement kiln.But cement using predecomposition technology just part has solved the low problem of heat transfer efficiency.Still exist very long branch to ungird and the thermopositive reaction band in the rotary kiln of cement nsp kiln, heat transfer efficiency is still not high, and the result is that the energy consumption of nsp kiln still exceeds one times nearly than the theoretical hear rate of burning clinker of cement.

The cement fluidized calcination is a kind of technology of utilizing fluidized-bed to finish to burn till.Fluidized-bed helps the heat transfer between suspended particles and the air-flow, but is helpless to solid state reaction and burns till reaction.The main solid state reaction that cement forms is the reaction of diffusion control: 2CaO+SiO ₂=C ₂S; Mainly burning till reaction is fusion crystallization reaction under the liquid phase catalyst: CaO+C ₂S=C ₃S.For improving solid state reaction and the efficient of burning till reaction, need contact closely between the kiln material, but the particle in the fluidized-bed is in suspended state all the time, the probability of collision between the particle is very low.So fluidized calcination needs very high gas velocity keep fluidized, also need also to finish for a long time solid-state and burn till reaction, the electric energy of consumption is very high.

Cement clinker forms the need hear rate of each section and asks for an interview table 1:

As known from Table 1: after lime carbonate decomposes, be warming up to 1400 ℃ of heat absorption 522kJ/kg-Cl from 900 ℃, average every intensification needs hot 104kJ/kg-Cl for 100 ℃ approximately, forms liquid phase heat absorption 109kJ/kg-Cl, adds up to heat absorption 631kJ/kg-Cl.On the other hand, clinker mineral forms heat release-408kJ/kg-Cl.Amount to, 900 ℃ of later hot revenue and expenditures offset and still need to kiln material heat supply 223kJ/kg-Cl.Help under the suspended state conducting heat, help material contact and reaction under the stacking states.In the cement nsp kiln, the kiln material is heated to CaCO ₃Decompose 90% (about 900 ℃) and just send into rotary kiln, the deficiency that suspends, accumulation are had a surplus.In the cement fluidized calcination kiln, the kiln material is in fluidized state all the time, and superfluous, accumulation shortage suspends.So, need a kind of novel, cement firing process technology efficiently of exploitation.

Table 1 grog forms heat effect and calculates

	Heat effect kJ/kg-Cl	Heat effect %	Accumulative total heat effect kJ/kg-C1	Accumulative total %
					CO 2Cooling heat release H 2O cooling heat release kiln material rises to 450 ℃ of clay kin material by 0 ℃ and rises to 600 ℃ of crystalline clay mineral magnesiumcarbonate by 450 ℃ and decompose the kiln material and rise to 900 ℃ of lime carbonate by 600 ℃ and decompose the kiln material and rise to 1400 ℃ of clinker minerals by 900 ℃ and forms heat release and form the liquid phase grog and cool off	-504 -68 734 134 249 -28 57 542 1926 522 -408 109 -1530	-29 -4 42 8 14 -2 3 31 111 30 -24 6 -88	-504 -572 162 296 545 517 574 1116 3042 3564 3156 3265 1735	-29.0 -33.0 9.3 17.1 31.4 29.8 33.1 64.3 175.3 205.4 181.9 188.2 100.0

Summary of the invention:

The object of the present invention is to provide and a kind ofly improve cement output, reduce and to burn till hear rate and grinding pow consumption, and can improve the new cement presintering production method of clinker quality.

A kind of cement presintering production method provided by the invention enters pre-burning stove with material through pre-thermal sub-system, enters rotary kiln via subordinate whirlwind tube again, wherein: will be set at 950 ℃～1250 ℃ from the temperature of charge that subordinate whirlwind tube enters rotary kiln.

In the aforesaid method, position use carborundum content 〉=30% or zircon content 〉=30% or magnesia-alumina spinel refractory in that kiln odd amount in addition to the round number system is easy to take place skinning prevent skinning, obstruction.

Concrete, with the hanger brick of SiC content 〉=80% inner sleeve as subordinate whirlwind tube; The metal parts that uses superalloy, silicon carbide, silicon nitride, match dragon high-performance ceramics or have a refrigerating unit is made the discharging air valve and the charging spreading plate device of subordinate whirlwind tube; Transitional zone is built by laying bricks or stones by the magnesium aluminate spinel composite brick that has thermofin in the described rotary kiln.

The present invention also provides a kind of cement presintering production system, comprise kiln odd amount in addition to the round number system and single-revolution kiln that a pre-thermal sub-system, a pre-burning stove and subordinate whirlwind tube are formed, wherein, in the tapering of the funnel uptake of the easiest skinning, next stage whirlwind tube, position, blanking slope is used and is contained 80% or contain the material of 30%SiC; At the SiC or the zircon material that use content above 30% than positions such as the pre-burning stove that is easier to skinning, the straight tubes of next stage whirlwind tube; When sulphur alkali during, use dimension stone of magnesia alumina spinel at the position of easy skinning than Q＜1; The inner sleeve of described subordinate whirlwind tube is made with 80%SiC matter hanger brick; The discharging air valve of described subordinate whirlwind tube and charging spreading plate device are made with superalloy, silicon carbide, silicon nitride, match dragon high-performance ceramics or the metal parts that has a refrigerating unit; Transitional zone is built by laying bricks or stones by the magnesium aluminate spinel composite brick that has thermofin and is formed in the described rotary kiln.

In the said system, described rotary kiln length-to-diameter ratio is 8～12, and rotating speed is 3～6 rev/mins, and gradient is 3.5～5.0%.

Adopt above technical scheme, go into the kiln temperature of charge by improving rotary kiln, reduce or eliminate residual poor efficiency heat transfer process in the cement rotary kiln significantly, hot bottleneck problem during solution cement burns till, realize fast the burning and efficient cooling of particulate of grog, and by adopting resistive connection leather material, high temperature material and lagging material, the supplementary measures such as length-to-diameter ratio, rotating speed and gradient that change rotary kiln realize invention, thereby produce fairly obvious raising cement output, reduce the net effect burn till hear rate and grinding pow consumption, raising clinker quality.

Embodiment:

Technological line of the present invention, be that the kiln temperature of charge of going into of pre existing thermal sub-system is brought up to (950～1250 ℃) about 1100 ℃ from 900 ℃, be about to improve about 200 ℃ or higher into the kiln temperature of charge is clean, eliminate the heat transfer " bottleneck " of cement rotary kiln, realize that zero hear rate even the negative hear rate of cement clinker in the rotary kiln burn till fast, thereby reach the target of volume increase, energy-conservation and raising clinker quality.

At first, the present invention should provide remaining carbonate decomposition and kiln material even the required heat of thermopositive reaction temperature in the rotary kiln.The carbonate decomposition rate that the cement nsp kiln is gone into the kiln material only is 90%, and 10% remaining carbonate still need decompose in rotary kiln.As shown in Table 1: these CaCO ₃Decomposing needs heat 10% * 1926=193KJ/kg-Cl.CaCO ₃After the decomposition, also need just can finish and burn till to kiln material heat supply 223KJ/kg-Cl.Amount to heat supplied and reach 193+223=416KJ/kg-Cl.The present invention will go into the kiln temperature of charge and be increased to 950～1250 ℃, obviously reduce or fully phased out the heat transfer process of above-mentioned inefficiency, only need spray into small amount of fuel at kiln hood and control knot grain and control formation kliner coating, obviously improve the cement firing condition.

Secondly, the present invention has quickened exothermal reaction process.Because the kiln material just drops in the kiln after being heated to the temperature that thermopositive reaction takes place, after contacting closely, the kiln material, further accelerated the speed of solid state reaction and heat up with very fast response and intensification.Like this, solid state reaction will be finished with very fast speed.

The 3rd, the present invention has accelerated sintering process, helps improving clinker quality, reduces and burn till hear rate and grinding pow consumption.Because free CaO and C ₂S does not have plenty of time to grow up, fusion crystallization reaction CaO+C ₂S=C ₃The speed of S is improved, and the firing time of cement will be shortened, and the output of grog increases.On the one hand, the area of dissipation of unit grog reduces, and helps reducing burning till hear rate.On the other hand, the activity of clinker mineral is improved, and clinker particle does not have time enough to grow up yet.Like this, the grindability of the effect of chilling, refrigerative efficient, grog can obtain change in various degree, thereby helps improving cement clinker quality, reduces grinding pow consumption.

Presintering cement production system of the present invention referring to accompanying drawing 1, comprises by a pre-thermal sub-system, a pre-burning stove, and connect kiln odd amount in addition to the round number system and the single-revolution kiln that the subordinate whirlwind tube of pre-burning stove and pre-thermal sub-system is formed.In this system, form pre-thermal sub-system by four to six grades of cyclones; Pre-thermal sub-system is preheating to 820-880 ℃ with raw material, deliver to and carry out presintering in the pre-burning stove, pre-sintering temperature is controlled at 950～1250 ℃, material after the presintering carries out gas solid separation through subordinate whirlwind tube, material enters rotary kiln after next stage whirlwind tube separates, forward the kiln hood discharging to after burning till through the transitional zone (950/1250～1300 ℃) of rotary kiln and clinkering zone (1300～1500 ℃).In the system, the waste gas of rotary kiln enters the bottom of pre-burning stove by funnel uptake, accounts for the coal of supplying with total heat 65-90% and sends into pre-burning stove with tertiary air, and the coal of residue 35-10% is sent into kiln hood with a wind.

The structure of whirlwind tube of the present invention is referring to accompanying drawing 2.The inner sleeve 3 of subordinate whirlwind tube adopts exotic materialss to make, and the air valve of its lower end material outlet 31, top spreading plate 33 are also made by exotic materials, and upper end outlet pipe 32 also adopts exotic materials to make.

In conjunction with above-mentioned design, the present invention will take following critical concrete measure to guarantee the realization of aforementioned imagination:

1, adopt the resistive connection leather material to prevent to stop up

Contain volatile elements such as K, Cl, S in raw material that cement kiln uses and the fuel.These volatile elements are evaporated thermal zone, are condensate on the kiln material of cold zone, be preheated device and dust precipitator receive layer by layer pounce on after, again with the kiln material enter thermal zone once more the volatilization, until reaching balance.After balance is set up, K ₂But 5 times of O enrichments; SO ₃But enrichment 3-5 doubly; Cl can enrichment 80-100 doubly.The existence form of volatile matter is more definite than Q by sulphur alkali:

$Q=\frac{{\mathrm{<figure-callout\; id="3"\; label="SO"\; filenames="A20071014756400101.png"\; state="\{\{state\}\}">SO</figure-callout>}}_3/80}{(K_{2}O/94)+(N{a}_{2}O/62)-(\mathrm{Cl}/71)}---1)$

Q＞1 o'clock, the SO3 in the volatile matter is superfluous state, forms hard skinning; During Q=1, volatile matter is neutral state, forms harder skinning; Q＜1 o'clock, the K2O in the volatile matter is superfluous state, forms loose skinning.Most situations are: Q 〉=1.That is to say: the K that evaporates at first reacts with Cl, forms KCl, and remaining K forms K again ₂SO ₄If also remain SO ₃, will form CaSO ₄

Only 776 ℃ of the fusing points of KCl; KCl and CaSO ₄Minimum eutectic temperature more have only 687 ℃.These low melting points will make the kiln material have certain viscosity, make the kiln material stick to refractory surface, form loose status nascendi skinning.CaO in the status nascendi skinning can absorb the SO in the kiln gas ₃, form more CaSO ₄Subsequently, K ₂SO ₄2CaSO ₄, 2C ₂SCaSO ₄, 2C ₂SCaCO ₄Form in a large number etc. feature skinning mineral.Skinning becomes more solid and more solid, and is long more big more, has to stop kiln ability processing accident so that develop into.

The present invention prevents skinning with the refractory materials that employing contains SiC or ZS (zircon) or MA (magnesium-aluminium spinel).SiC is to be main compound with covalent linkage, its structure be that material of main part is significantly different with the ionic linkage.It is generally acknowledged: SiC is heated to 800 ℃ of beginning oxidations in air; In the time of 1000-1300 ℃, form SiO ₂Glass film, oxidation-resistance is better; After 1300 ℃, rate of oxidation is accelerated; After 1600 ℃, SiC is just very fast, and oxidation is burnt.

The SiC content of refractory materials surpasses after 30%, will form fine and close SiO at material surface after the SiC slow oxidation ₂Film, shutoff refractory materials open pore makes O ₂Be difficult to diffuse into from material internal, prevented that SiC from continuing oxidation, also make the kiln material be difficult to adhere to.Simultaneously, SiC also has high thermal conductivity, and thermal expansivity and skinning are also inequality.After adhering to skinning, the temperature of SiC material reduces, volumetric shrinkage is very big, and skinning will be peeled off spontaneously.The refractory materials that contains 30% above zircon also has the effect of similar SiC.

Q＜1 o'clock, K ₂O can corrode SiO ₂Tight zone weakens the resistive connection skin effect of SiC.At this moment, can use dimension stone of magnesia alumina spinel.Magnesium-aluminium spinel is weakly alkaline mineral, and the alkalescence and the erosion of acidulous material are had good resistivity.Below 1300 ℃, magnesium-aluminium spinel discord CaO reaction.More than 1300 ℃, the refractory materials that magnesium-aluminium spinel content is high is not also hung kliner coating.So, can prevent skinning with the refractory materials of high magnesium-aluminium spinel content.

The present invention has improved raw material and has gone into the kiln temperature, and kiln odd amount in addition to the round number system is more prone to take place skinning.So the position that needs kiln odd amount in addition to the round number system to be easy to take place skinning uses special refractory materials to replace used alkaline-resisting clay brick, to prevent the generation of skinning, obstruction, these positions are:

In the position of easy skinning, as the tapering of rising flue, next stage whirlwind tube, position, blanking slope is used and is contained 80% or contain the material of 30%SiC; Use content to surpass 30% SiC or zircon material at other positions.When sulphur alkali during than Q＜1 (this numerical value is relevant with crude fuel), use dimension stone of magnesia alumina spinel at the position of easy skinning.

2, adopt SiC matter high grade refractory

Improve the kiln material temperature, will increase the temperature of subordinate of kiln odd amount in addition to the round number system whirlwind tube inevitably.After the increase in temperature of whirlwind tube, its original high temperature steel inner sleeve is burnt easily, and the dust-collecting efficiency of this whirlwind tube and the hear rate and the power consumption of kiln system are affected.So need using SiC content is that 80% high-strength SiC matter hanger brick replaces heat-resisting steel to make the inner sleeve of whirlwind tube.SiO ₂In conjunction with 1400 ℃ of hot modulus of rupture 〉=30MPa of high-strength SiC refractory materials, can satisfy the requirement of making hanger brick.

3, adopt superalloy or high-performance ceramics material

After temperature improved, heat-resisting steel devices such as the air valve of whirlwind tube and spreading plate also were easy to be burnt.So, need to adopt superalloy, even make high-performance ceramics make these parts.Concrete using method will be determined according to working temperature.Below 1150 ℃, can use superalloy, 1200 ℃ more than the temperature, must use high-performance ceramics materials such as silicon carbide, silicon nitride, match dragon or use to have the metallic substance of refrigerating unit.

4, adopt composite refractory brick

Be provided with in original rotary kiln that branch ungirds, transitional zone and clinkering zone, wherein transitional zone mainly adopts periclasite-dimension stone of magnesia alumina spinel as wadding, because transitional zone does not have kliner coating, the thermal conductivity of Mg-Al spinel brick is very high again, and the heat lost by radiation of rotary kiln transition belt section kiln body is very big.After the present invention improved the kiln material temperature, the branch of having cancelled rotary kiln ungirded, and material directly enters transitional zone, and the ratio of transitional zone is longer, as adopted original wadding, and the heat lost by radiation of transitional zone is then more obvious.So the present invention adopts the magnesium aluminate spinel composite brick have thermofin to build the transitional zone of rotary kiln by laying bricks or stones, the part of the 60-75% of this composite brick be densification and purity higher magnesium-aluminium spinel (MgO+Al ₂O ₃〉=95%) the magnalium based material (MgO+Al that, the partially porous purity of 25-40% is lower ₂O ₃≤ 95%), to reduce heat radiation and further to cut down the consumption of energy.

5, adopt the rotary kiln of novel texture

The length-to-diameter ratio of the kiln of existing rotary kiln is big, rotating speed and gradient are lower.So, in order to obtain better volume increase, energy-saving effect, after caking power is strengthened, must be decreased to 8～12 with the length-to-diameter ratio of rotary kiln from existing 12～16; The rotating speed of rotary kiln from existing 2～3 rev/mins, is increased to 3～6 rev/mins; The gradient of rotary kiln from 2.5～4.0%, is increased to 3.5～5.0%, so that burned grog is in time transferred out clinkering zone.If use existing rotary kiln, amount of increase in production is 20～40% scene.After adopting the rotary kiln of novel texture, amount of increase in production then can reach 40～80%, even higher, can also realize that particulate burns soon, improves the intensity of grog, increases the grindability of grog, obtains better effect.

Below in conjunction with an example in detail the present invention and technique effect thereof are described in detail:

Certain cement mill kiln designed productive capacity 5000t/d, wherein the rotary kiln specification is φ 4.8 * 72m, kiln speed is 1～4r/min, decomposing furnace is the TDF pattern, specification is φ 7.7m, level Four dual system preheater diameter is respectively φ 4.5m, φ 6.6m, φ 6.6 and φ 6.8m, and the chemical ingredients of raw material, coal ash and grog sees Table 2, and the technical analysis of coal dust sees Table 3.

The chemical ingredients of table 2 raw material, coal ash and grog

Project	Unit	Grog	Raw material	Coal ash
					Loss	％	0.78	36.5	2.00
SiO 2	％	21.98	13.98	49.80
					Al 2O 3	％	4.98	3.02	28.84
Fe 2O 3	％	3.61	2.18	5.11
					CaO	％	65.15	43.48	6.49
MgO	％	1.18	0.58	2.74
					K 2O	％	1.04	0.67	3.59
SO 3	％	0.36	/	3.34
					N aO	％	0.05	0.08	1.24
fCaO	％	0.87	/	0.44

The technical analysis of table 3 coal dust

Analysis project	Mad.％	Aad.％	Vad.％	Qnet.arMJ/Kg
					Coal dust in the heap	2.65	22.80	27.60	23.30

Raw material by per hour 36.75 tons be admitted to preheater, go into rotary kiln through preheater preheating, decomposing furnace after decomposing.The hot raw material temperature of going into rotary kiln is 910 ℃, and the carbonate decomposition rate is 90%.The output of cement kiln grog is per hour 22.27 tons.The rotary kiln coal consumption is per hour 20.2 tons for per hour 11.80 tons, decomposing furnace coal consumption, and it is 3336kJ/kg that cement clinker burns till hear rate.Thermal load is 274 * 10 in the kiln ⁶Thermal load is 469 * 10 in the kJ/h, stove ⁶KJ/h.Cement clinker strength is 58.4MPa (28d).

By implementing the present invention, promptly decomposition furnace structure is transformed according to aforementioned content, obtain following The operation result:

Raw material by per hour 44.28 tons be admitted to preheater, go into rotary kiln through preheater preheating, decomposing furnace after decomposing.The hot raw material temperature of going into rotary kiln is 1180 ℃, and the carbonate decomposition rate is 100%.The output of cement kiln grog is per hour 26.93 tons.The rotary kiln coal consumption is per hour 12.01 tons.The decomposing furnace coal consumption is per hour 22.26 tons, and it is 2905kJ/kg that cement clinker burns till hear rate.Thermal load is 279 * 10 in the kiln ⁶Thermal load is 492 * 10 in the kJ/h, stove ⁶KJ/h.Cement clinker strength is 62.7MPa (28d).

Implementing before and after the present invention the contrast of relevant technologies index is listed in the table below in 4.

The contrast of table 4 technical indicator

Project	Before the enforcement	After the enforcement	Increasing value
				Raw material feed quantity (t/h)	36.75	44.28	20.5％
Go into kiln raw material temperature (℃)	910	1180	270℃
				Carbonate decomposition rate (%)	90	100	-
Cement clinker output (t/h)	22.27	26.93	20.9％
				Cement clinker burns till hear rate (kJ/kg)	3336	2905	-9.1％
Cement clinker 28d intensity (MPa)	58.4	62.7	4.3MPa

More as can be seen, by implementing the present invention, raising cement output that can be fairly obvious (improving more than 20%) reduces and burns till hear rate (reducing by 9%), and can improve the intensity of cement clinker by above example.The present invention can reduce or eliminate residual poor efficiency heat transfer process in the cement rotary kiln significantly, the hot bottleneck problem during solution cement burns till.

Claims (7)

1. cement presintering production method enters pre-burning stove with material through pre-thermal sub-system, enters rotary kiln via subordinate whirlwind tube again, it is characterized in that: will be set at 950 ℃～1250 ℃ from the temperature of charge that subordinate whirlwind tube enters rotary kiln.

2. according to the described cement presintering production method of claim 1, it is characterized in that: position use carborundum content 〉=30% or zircon content 〉=30% or magnesia-alumina spinel refractory in that kiln odd amount in addition to the round number system is easy to take place skinning prevent skinning, obstruction.

3. according to claim 1 or 2 described cement presintering production methods, it is characterized in that: with the hanger brick of SiC content 〉=80% inner sleeve as subordinate whirlwind tube.

4. according to claim 1 or 2 described cement presintering production methods, it is characterized in that: the metal parts that uses superalloy, silicon carbide, silicon nitride, match dragon high-performance ceramics or have a refrigerating unit is made the discharging air valve and the charging spreading plate device of subordinate whirlwind tube.

5. according to claim 1 or 2 described cement presintering production methods, it is characterized in that: transitional zone is built by laying bricks or stones by the magnesium aluminate spinel composite brick that has thermofin in the described rotary kiln.

6. cement presintering production system, comprise kiln odd amount in addition to the round number system and single-revolution kiln that a pre-thermal sub-system, a pre-burning stove and subordinate whirlwind tube are formed, it is characterized in that, in the tapering of the funnel uptake of the easiest skinning, next stage whirlwind tube, position, blanking slope is used and is contained 80% or contain the material of 30%SiC; At the SiC or the zircon material that use content above 30% than positions such as the pre-burning stove that is easier to skinning, the straight tubes of next stage whirlwind tube; When sulphur alkali during, use dimension stone of magnesia alumina spinel at the position of easy skinning than Q＜1; The inner sleeve of described subordinate whirlwind tube is made with 80%SiC matter hanger brick; The discharging air valve of described subordinate whirlwind tube and charging spreading plate device are made with superalloy, silicon carbide, silicon nitride, match dragon high-performance ceramics or the metal parts that has a refrigerating unit; Transitional zone is built by laying bricks or stones by the magnesium aluminate spinel composite brick that has thermofin and is formed in the described rotary kiln.

7. according to the described cement presintering production system of claim 6, it is characterized in that described rotary kiln length-to-diameter ratio is 8～12, rotating speed is 3～6 rev/mins, and gradient is 3.5～5.0%.

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