CN85106835A - Produce the apparatus and method for of white cement clinker - Google Patents

Abstract

The method and apparatus that the present invention produces white cement clinker is to use the fuel of low heat value (LCV), as the coal gas that producer gas generator is produced, is directly used in the burning in the rotary kiln 5.Thereby LCV gas is the grog produced in rotary kiln in the clinker cooler 9 of fs directly to carry out heat exchange and is preheating to suitable temperature, no longer again, the degree of oxidation when grog then is cooled to always and directly contacts with air, then grog further directly carries out heat exchange with air in subordinate phase water cooler 13, through the air of preheating just as combustion air feeding rotary kiln 5.

Description

Produce the apparatus and method for of white cement clinker

This invention is the relevant apparatus and method for of producing white cement clinker in rotary kiln.

People can distinguish white cement and traditional portland cement from color, yet, in fact, their chemical property, physical properties all is the same with Chemical Composition.In general, the composition of the raw material of making white cement is: 75～85% Wingdale; 5-20% kaolin or clay and 4～15% sand.Yet some element in the raw material promptly is that the content of iron, manganese and chromium is low as much as possible specifically, to keep the pure white degree of white cement.

In general, the ferric oxide (Fe in the white cement clinker ₂O ₃) content should be lower than 0.40%, the content of manganese oxide (MnO) should be lower than 0.040%, chromium sesquioxide (Cr ₂O ₃) content should be lower than 30/1000000ths.In producing the white cement process, pollute and also can produce about 0.05～0.10% ferric oxide, so the starting material of white cement will possess following condition at least, Wingdale trioxygen-containingization two iron amounts must be lower than 0.25%, three oxidations, two oxygen levels of kaolin or clay can not surpass 0.5%, and the ferric oxide content in the sand must be lower than 0.2%.

But owing to above-mentioned element can not be avoided fully, and owing to the metal positive ion light absorpting ability that is in the high price state is the highest, state is the key that obtains high whiteness cement so keep metal at a low price.Grog can be placed reducing gas, if till when the temperature of grog is lower than them and directly is exposed to airborne words the temperature of oxidation can take place.

In the processing of white cement, such as from UK Patent Application 814, No. 836 (GB-A814,836) as can be known, be that raw material is added in the rotary kiln, sinter cement clinker inside into.Grog leaves rotary kiln and enters in the cylinder drier that is full of reducing gas in the time of about 1200 ℃, enter then in the water of water tank, takes out with conveyor after the cooling again.This method has its shortcoming, be exactly that grog is must be soon in addition dry, and also residual in the grog 12～18% moisture content arranged, so just relatively weakened cement intensity, if utilize mink cell focus in cylinder drier, to produce gas, can often find to leave the carbon spot above the grog material, adopt the thermal exhaust of rotary kiln to come dry cement clinker if change, dust can pollute grog again in the kiln, both just finished drying process soon, also make grog absorb a certain amount of moisture content inevitably, weaken cement intensity, further the cooling grog also has shortcoming in water tank: water vapor must be scurried into rotary kiln, and this may cause the unkehr effect of thermograde, and can increase gas volume in the whole kiln internal loading, thereby cause the contained heat of grog almost to exhaust.

Up to the present, adoptable combustion fuel is fuel oil or Sweet natural gas only, and can not use coal, because coal ash can pollute, and coal can not guarantee to reach sufficiently high temperature in the sintering zone of grog.The fuel that is used for sintered clinker, sufficiently high caloric value must be arranged, the scope that is adiabatic flame temperature (AFT) is 1850 ℃～2050 ℃, up to the present, have only the AFT of fuel oil and Sweet natural gas can satisfy this requirement near 2015 ℃, low heat value (LCV) coal gas that this technical requirements regulation can not adopt gasification of coal to obtain is because in 400 ℃ of typical temperature outs of coal gasifier, its AFT can only reach 1840 ℃.

The shortcoming of known production white cement the whole bag of tricks can be summarized as follows:

1. can only use high heating value, from but more expensive fuel.

2. grog is immersed the moisture content of meeting residual 12～18% in the water, thereby weaken cement intensity, and form bad thermograde and increase the interior gas load of kiln.

3. to get rid of the residual moisture content in the grog, if with oil firing cylinder drier (oil drum dryer) exsiccant method then can cause Prevent Carbon Contamination, if can cause dust pollution with the dry rule of heating kiln exhaust.

4. lose the possibility that reclaims the thermal content in the grog.

Purpose of the present invention is exactly in order to overcome the above-mentioned various shortcomings of producing in the white cement process.According to method of the present invention, white cement clinker rotates in the sintering oven one and generates, in reducing gas, carry out the cooling first time behind the kiln discharge, in this cooling stages, make its temperature be cooled to grog temperature of oxidation again not when directly contacting thereby employing is directly carried out heat exchange with LCV fuel gas, enter second cooling stages-directly contact then with cooling air with air.The LCV fuel gas that is preheated at first cooling stages input rotary kiln that then acts as a fuel; The freezing air that is preheated at second cooling stages then enters rotary kiln as combustion air.

Therefore the present invention might reclaim the thermal contents in the grogs in a large number, and, simultaneously can be to the heating of LCV fuel gas, it is reached can be for the degree of sintering oven direct sintering.

Low heat value (LCV) gas is that a kind of thermal content is 100～150BTU/scf[British thermal unit/standard cubic foot] fuel gas.

Cement clinker contacts with low calorie fuels gas in heat exchanger with rotating bed, fixed bed, fluidized-bed or cyclone bed or water cooler, and this promptly is first cooling stages.From adiabatic temperature approximately is 1950 ℃, and cement clinker is cooled at least 600 ℃ and estimates that in this way, the temperature of LCV fuel gas is heated to 850 ℃ at least.Like this, the cooled temperature of cement clinker just is lower than the temperature when oxidation takes place, and this makes in the cement clinker remaining heat to reclaim by contacting with air in direct contact type heat exchange or water cooler (preferably adopting heat exchanger or the water cooler that cools off the equal model of employing with LCV fuel gas).The air of preheating can be as the combustion-supporting gas in the kiln like this.

It is disclosed to resemble UK Patent Application No. 1171568 (GB-A-1171568), and spraying water in the kiln bottom is cooled to about 1100 ℃ for the first time.Both can reach needed strength of cement with this rapid cooling method; In cement clinker, still exist enough heats to heat LCV gas again, make it reach directly incendiary temperature.This same heat exchanger also can be used as the equipment that reduces the cement clinker water content.

Cement clinker preferably can cool below 600 ℃ in the LCV gas heat exchanger, prevents when cement clinker is exposed in the air oxidized.For this purpose, grasp cooling time at 5～10 minutes to well.

This invention comprises that also a cover is used to realize the equipment of this novel method, comprising: a preheater that relies on heating kiln gas to come preheating material; One is used for burning and raw materials for sintering makes it or the rotary type rotary kiln of cement clinker; And one cover be used to cool off the refrigerating unit of the grog that rotary kiln produces, it is characterized in that this cover refrigerating unit comprises a first heat exchanger that has cement clinker and a LCV gas feed and secondary heat exchanger-be used for the receiving cement clinker that transports out from first heat exchanger, it also has a gas inlet in addition, and these two exchanging air all have the pneumatic outlet that leads to rotary kiln.

By coal gasification, can produce LCV gas expediently.Utilize producer gas generator just can be easy to produce and contain ash LCV fuel gas very low, that meet processing requirement, if necessary, can install dust removal filter in the back of producer.The example that is applicable to the typical producer of this purposes has Foster Weiler (Foster Wheeler) producer gas generator.It is the producer of two layers of fixed-bed type, and from the top adding feed coal of producer, raw material flows downward gradually, relies on the mixed gas of make progress one air of mobile and water vapor to gasify.

The upper strata of producer relies on the distillment in the volatilization coal to produce the quite low coal gas (120 ℃) of temperature, and this coal gas has been got rid of wherein the heaviest composition by a coal tar cyclonic separator.The lower floor of producer produces 600 ℃ coal gas from the pneumatolysis district, give this dedusting in a swirler, mixes with top coal gas then, just provides a kind of 400 ℃ LCV gas.Utilize this producer, and gas preheating is arrived more than 850 ℃ at least, just might utilize the fuel of relatively cheap coal as rotary kiln.

The device of processing and fabricating white cement of the present invention is described with sketch below.

Raw material is imported preheater 2 by inlet 1, the hot gas that comes out with rotary kiln 5 is with raw material preheating there, the raw material of preheating is delivered to 5 li of rotary kilns by pipeline 3, at raw material from the process at the bottom of rotary kiln top is transported to kiln, grog is burnt till from the temperature of 1400～1500 ℃ of orders approximately in skilled district at kiln, end at rotary kiln, water spray with input water pipe 6, grog is cooled to about 1100 ℃, be loaded into primary cooler 9 through passage 7 then, there, grog be cooled to about 600 ℃ by direct the contact with passage 11 input LCV gases, through passage 12 grog is transported to recooler 13 from water cooler 9, the air of being introduced by pipeline 14 by direct contact cools off, and makes the temperature of grog be cooled to 100～150 ℃, after, cement clinker just from pipeline 15 outputs, leaves water cooler 13.

LCV gas obtains from the producer gas generator 19 with 16,17,18 3 inlets.These three inlets are accepted coal respectively, air and water vapor.Coal is from 16 addings that enter the mouth.

LCV gas arrives strainer 21 by a pipeline, and coal ash and other particle are removed through filter, discharges through exporting 22.LCV gas then arrives water cooler 9 by strainer 21 through pipeline 11.

LCV gas leaves strainer greatly in the time of 400 ℃, and is about 1950 ℃ from AFT and estimates that through supercooler 9 direct contact heat grogs, the LCV gas temperature can reach about 850 ℃.Afterwards, introduce the exhaust end of rotary kiln 5 through pipeline 8.Air in the subordinate phase water cooler 13 be through with the grog heat exchange, be heated to after 300～500 ℃ by pipeline 14 and introduce, leave heat exchanger 13 is input to rotary kiln 5 as combustion air exhaust end by pipeline 10.

Gas in the rotary kiln arrives preheater 2 by passage 4 again, utilizes the mode preheating material of direct heat exchange, after strainer and the chimney that does not mark among figure of pipeline 23 inputs.

Following embodiment further specifies advantage of the present invention:

0.766kg LCV gas/kg cement clinker is delivered in the rotary kiln through first water cooler, LCV gas approximately is 850 ℃ in the temperature out of first water cooler, be that the AFT temperature can reach 1950 ℃, by contrast, if without the fs water cooler, temperature has only the AFT of 400 ℃ LCV gas can only reach 1840 ℃.Cement clinker then flows into second water cooler, and in second water cooler-air-cooler, adopts the freezing air of 1.39kg air/kg cement clinker.Air themperature reaches 300～500 ℃ when leaving the freezing air district.The thermal cycling amount of first cooling stages is equivalent to about 125 kilocalories/kg, and the thermal cycling amount of second cooling stages is equivalent to 125 kilocalories/kg too, and like this, the thermal cycling total amount that enters system is 250 kilocalories of/kilogram cement clinkers.

Claims (7)

1, a kind of method of in rotary kiln, producing white cement clinker, the grog that wherein comes out from kiln directly carries out heat exchange with the fuel gas of low heat value (LCV) in reducing gas, carry out the fs cooling, be cooled to grog when contacting with air, the temperature of oxidation can not take place again, just enter second cooling stages later on and directly contact, introduce rotary kiln through the LCV of preheating fuel gas and act as a fuel, introduce rotary kiln as combustion air at the freezing air that subordinate phase is preheated with cooling air.

2, the described method of claim 1, wherein cement clinker earlier in the bottom of kiln, made its temperature greatly to reducing to 1100 ℃ by the method for spraying water before being cooled off by LCV fuel gas.

3, claim 1 or 2 described methods, wherein grog is cooled within 100～150 ℃ of scopes at second cooling stages, and in the scope of preheating of air to 300～500 ℃.

4, the described method of claim 1 wherein with coal gasifier production low heat value (LCV) fuel gas, and at first cooling stages, is heated at least 850 ℃.

5,, in single-revolution kiln device, produce the method for white cement clinker substantially according to the described mode of accompanying drawing.

6, a cover is used to realize the equipment of the production method of one of above-mentioned arbitrary claim, comprising: a preheater with heating kiln gas preheating material; One is used for burning and raw materials for sintering becomes the rotary type firing of cement clinker; The refrigerating unit of cement clinker in the one cover cooling kiln, characteristics of this cover refrigerating unit are: the fs interchanger that comprises a LCV gas inlet that grog is arranged and produced by coal-gas producer; A subordinate phase interchanger that is used for receiving the grog that comes out from the fs interchanger has a gas inlet on it, these two interchanger all have pneumatic outlet to lead to rotary kiln.

7, turn round the rotary kiln device basically as shown in drawings.

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