WO2000056678A1

WO2000056678A1 - A line for clinker burning

Info

Publication number: WO2000056678A1
Application number: PCT/CZ2000/000016
Authority: WO
Inventors: Jaroslav POSPÍŠIL; Josef ŽAJDLÍK; Zdeněk MICHÁLEK; Petr KREJČÍ; Alois Pumprla; Alois SEHNÁLEK
Original assignee: Psp Engineering A.S.
Priority date: 1999-03-19
Filing date: 2000-03-14
Publication date: 2000-09-28
Also published as: SK14192001A3; CZ9900964A3; SK286042B6; RU2209790C2; UA67833C2; CZ292764B6

Abstract

The invention consists in a line for clinker burning, composed from a rotary kiln, to it connected air clinker cooler and from a pre-heater of powdered raw material arranged before the rotary kiln, where the pre-heater is composed from a system of vertically located and mutually serially interconnected cyclones with eventual addition of a shaft heat exchanger. The cooler (4) of clinker is provided with at least one output (45), which is with an interconnecting tube (450) ended to at least one from the connecting tubes (120, 130, 140) of middle part of vertical pre-heater (1).

Description

A line for clinker burning

Technical field of the invention

The invention deals with a line for clinker burning - namely for cement clinker - consisting from rotary kiln, to which a clinker air cooler with cooling air input to the cooling area and at least one heated up air output from the cooler is connected and where to this rotary kiln on the front end a pre-heater of powdered raw material, consisting from a system of mutually serially interconnected cyclones eventually in combination with a shaft heat exchanger is situated.

The prior art

At the up to now used lines for clinker burning, namely cement clinker, is one part of the heat - acquired at clinker cooling after output from the rotary kiln - is conducted with aid of pre heated air into the combustion process in the rotary kiln, eventually into the connected equipment for pre calcining, which is a part of such lines. The remaining heat is mostly not used in the given technological process of burning and it is led outside the cooler in the warm waste air.

The clinker after falling out from the rotary kiln can be characterized as a mixture of greater parts, small granules and a great share of dust, all having high temperature closely under the limit for sticking into individual blocks. For cooling of such material seems to be recently a grate cooler as the most convenient, where the principle here is the exploitation of heat exchange at cross passage of cooling air, which is after acceptance of a certain part of thermal energy led out from the grate cooler area. From point of view of thermodynamics is such exchange less effective as for instance countercurrent heat exchange. The stepwise improvement of cement clinker production leads to perpetual decrease of specific heat consumption for clinker burning, and the result of this is the decrease of necessary cooling air volume, which is acquired in the connected cooling equipment, for instance in the mentioned grate cooler, and where such air could be in the next step used as pre heated air in the proper burning process. The consequence is that the necessary volume of pre heated burning air is smaller at more efficient burning. This has a consequence in excessive increase of burning air temperature, and the inconvenient consequence of this is in regard to the higher working temperature the decreased equipment lifetime, namely in the area of output end of rotary kiln, including the kiln burner and in the area of clinker input to the cooler, eventually also in the area of pre calcination.

In addition to these unfavorable facts, which are in certain extent hindering the practical application of further decrease of heat consumption at burning, an other disadvantage is the decrease of waste gas volume on their output from the rotary kiln. That means that started from a limit the luck of heat for pre heating and for partial calcination of material in the pre heater begins to manifest, while in the area of cooling of the clinker coming out from the kiln there is a rather unnecessary excess of heat.

The mentioned facts have globally the consequence the useless deterioration of burning economy and the lifetime shortening of the connected technological equipment, which is manifested unfavorably in increase of investment and operation costs to a production unit.

The aim of the invention

The above mentioned disadvantages and the unfavorable operation and heat balances are in a considerable extent removed by the object of this invention, which is a line for clinker burning, namely cement clinker, consisting from a rotary kiln, to which a air cooler of clinker is connected, which has a cooling air input to the cooling area and at least one output of heated up air from the cooler, and where to the said rotary kiln front end a raw material pre heater is arranged, where this pre heater is composed from a system of mutually serially interconnected cyclones eventually in combination with a shaft heat exchanger.

The essence of the invention is that at least one clinker cooler output is with aid of interconnecting tube ended to at least one of the interconnecting tubes of the vertical pre heater middle part, or eventually the interconnecting tube is with aid of a dividing member branched to at least two branches, each one from which is individually ended to one of interconnecting tubes of vertical pre heater middle part.

An other essence of the invention is - at the line for clinker burning, where the raw material pre heater is divided to two parts, to a high temperature part and to a low temperature part, which are mutually interconnected with a transferring tube - that the cooler is equipped with at least one couple of hot air output, a first hot air output with higher temperature and a second hot air output with lower temperature, whereas the first hot air output is with aid of interconnecting tube ended to at least one from the interconnecting tubes of middle part of vertical pre heater high temperature part and the second hot air output is with aid of additional interconnecting tube ended into the interconnecting tube of middle part of vertical pre heater low temperature part.

The essence of the invention is also, that the interconnecting tube and/or the additional interconnecting tube are ended into the interconnecting tube of vertical pre heater high temperature part and/or to the interconnecting tube of vertical pre heater low temperature part and this in a place, in which the hot gas temperature, flowing out from the previous level of vertical pre heater of powdered raw material, differs from the temperature of supplied hot air up to 20% as the most, whereas a regulation member is advantageously inserted to the interconnecting a/or additional interconnecting tubes.

The essence of the invention is also, that the rotary kiln input chamber removal tube into the lower cyclone forms a calcinating channel with fuel addition and with an additional tube of combustion air, which is connected with the grate cooler input area, where the additional tube and the interconnecting tube and/or the additional interconnecting tube are advantageously mutually connected with aid of interconnecting tube, which can be according to the invention equipped with a closing member.

The embodiment of a construction according to the invention enables the transfer of a part of thermal energy, which is acquired in the clinker cooler and which could be not reasonably used in the burning process, into the raw material pre heating area. By this the heat consumption for the burning is additionally decreased and on the one hand a less thermal and so also operational load of the more exposed areas of burning process and on the other hand the decrease of operational cost to unit production are achieved.

Overview of Figs on the drawing.

The examples of embodiment of a construction of equipment according to the invention are schematically demonstrated on the attached drawings, where on the Fig. no.l the line for clinker burning with traditional version of the pre heater and on the Fig. no. 2 a line with a thermally divided pre heater is demonstrated.

Examples of embodiment of invention.

The line for clinker burning in the construction version according to Fig no. 1 is composed from a vertical pre heater 1 of powdered raw material, from rotary kiln 3 and a grate cooler of burned clinker 4. The rotary kiln 3 is supported by rolling support 300 , on its front end the input chamber 30_located and on the kiln is ended with the clinker output 31.

The vertical pre heater 1 of powdered raw material is composed from a system of one over other located cyclones, from the lower cyclone IT , from the second, third and forth cyclones 12, 13, 14, and from the last upper cyclone 15. All these cyclones are mutually serially connected and they are with a known way interconnected from one hand with the interconnecting tubes of hot gas from 120 to 150, and from the other hand with their output tubes from 121 to 1_51 of powdered raw material such a way, that always the output tube of higher located cyclone - for instance the output tube 131 of third cyclone 13 - is led to the beginning of interconnecting tube of previous couple of cyclones - in the given example into the interconnecting tube 120 of lower cyclone 11 and the second cyclone 12.

The lower cyclone π is connected to the input chamber 30 of rotary kiln 3 at one hand with the output tube 11_1 of pre heated powdered raw material and at other hand by removal tube 110 , to which lower part the output tube 121 of pre heated powdered raw material of the consecutive - here of the second cyclone 12_ is ended. The output of warm gas from the upper cyclone 15_ is connected with aid of the removal tube 160 to the following, on the Fig no. 1 not demonstrated element of the technological system. Into the lower part of interconnecting tube 150 - to which the upper cyclone 15 is connected - the input 7_ of pre heated powdered raw material is ended. The construction details of individual elements of vertical pre heater 1_ are enough known and they have no influence to the essence of invention and for this reason they are not described in details.

The output 31_ of rotary kiln 3_ is ended into the input area 41_ of grate clinker cooler 4_, through which also the kiln burner 32_ is led through and where by this burner the technologically necessary operation temperature is achieved and by this also the corresponding technological process in the rotary kiln 3_. The grate cooler 4_ is composed from known grate 42_ , which is ended into the input chamber 44_ with pouring out hopper 440 , under which the conveyor 8_ is situated. Under the cooling grate 42_ there is in the body of grate cooler 4_ a system of collecting pits 420 situated. Into the area under the cooling grate 42_ is also the output of ventilators 43_ ended, from which one ventilator is demonstrated on the Fig no. l . The upper part of grate cooler 4 body is in this example embodiment provided with outputs - with first output 45_ and a second output 46_ of heated up cooling air, from which the first output 45_ is with aid of interconnecting tube 450 connected with the interconnecting tube 130 of vertical pre heater 1_ , further into this tube 450 a regulation element 451 is built in, for instance a butterfly valve. The second output 46 is with aid of interconnecting tube 460 connected to the following, for the object of invention not important technological equipment, for instance to a dust removal device.

On the Fig. no. 1 is further with dashed line a construction version demonstrated, at which is to the upper part of interconnecting tube 450 , with aid of a dividing member 452 - for instance a regulating valve - a additional branch 453 connected, where this branch is connected to the interconnecting tube 410 , which is ended to the fourth cyclone 14_ .

The upper part 41_ of grate cooler 4_ is with aid of additional tube 60_ of burning (combustion) air interconnected with the lower part of interconnecting tube 110 , where also the input 61_ of fuel for precalcination is ended. As it is shown with dashed lines on the Fig no. l, in one version the interconnecting tube 450 and the additional tube 60_ of combustion air could be mutually interconnected with aid of interconnecting tube 62_ , where this could be advantageously provided with a closing member 620 , for instance with a slide valve.

At the demonstration embodiment according to Fig no. 2 the vertical pre heater j, is divided into two parts, to high temperature part 10_ - composed from three vertically located and mutually serially interconnected cyclones of lower cyclone 11_ , of second cyclone 12_ and of third cyclone 13_ - and to a low temperature part 20_ - which is composed from lowest located shaft exchanger 21_ and from the following couple of cyclones, the lower cyclone 22_ and the upper cyclone 23_ . Both these parts are located in different height so, that input to the shaft exchanger 21_ of the low temperature part 20 is located lower as the output from the highest - third cyclone 13_ of the high temperature part 10_ and the parts are mutually interconnected by the transferring tube 5 of warm gas. The principles of construction of mutual interconnection of cyclones 1 _ to 13_ , eventually 22_ and 23_ and also the connection of lower cyclone 11_ to the input chamber 30_ of rotary kiln 3_ and the connection of input area 41_ of grate cooler 4 with the interconnecting 110 are principally the same with the construction according to Fig. no.l .

The demonstration embodiment according to Fig. no. 2 differs - beside the described division of vertical pre heater 1_ to two parts - from the previous one with it that the grate cooler 4_ is provided with a third output 47_ of hot air, which is provided with an output tube 470 and that the second output 46_ of hot air is in this case connected with aid of interconnecting tube 460 - on the Fig no. 2 drawn with dashed line - with the low temperature part 20_ of vertical pre heater 1_ , in the given case with the interconnecting tube 220 , which leads from the shaft exchanger 21_ to the lower cyclone 22_ . The output tube 211 of shaft exchanger 21_ is ended to the interconnecting tube 450 , which similarly as at construction according to Fig no.l connects the first output 45_ of grate cooler 4_ with the connecting tube 130 of high temperature part 10 of vertical pre heater 1_ . At this construction version the eventually used regulation element 451 inserted into the interconnecting tube 450 before the mouth of the output tube 211 .

The function of line for clinker burning is as follows. The propre burning is realized in the rotary kiln 3_ , to the input chamber 30_ of which the pre heated powdered raw material is led from the lower cyclone 1_1 with aid of output tube 111 . After material passing through the rotary kiln 3_ - in which the necessary technological process is realized - the formed clinker is led from the output 3J_ of rotary kiln 3_ into the input area 41_ of grate cooler 4_ and the clinker passes it with aid of movement of cooling grate 41_ to the output chamber 44_ , from where is with aid of the pouring out hopper 440 led with the conveyor 8_ in direction of arrow T_ for further processing.

At construction according to Fig. no. 1 the powdered raw material is led with input 7_ to the lower part of connecting tube 150 of vertical pre heater 1_ and with aid of hot gas - which flows in direction of arrow R_ - at its simultaneous heating up transported to the upper cyclone 15_ . After it is falling stepwise with usual way in direction of arrows S_ passing its individual lower cyclones 14_ to 12_ to the lower cyclone 11_ and from here to the input chamber 30_ of rotary kiln 3_ . At passing through connection tubes 140 to 120 and removal tube 110 the powdered raw material is heated up to higher temperature by the hot gases, which are passing in opposite direction of arrows R_ upwards from the rotary kiln 3. According to the invention is additionally into the middle part of connecting tube 130 added a part of hot air - from the first output 45_ of grate cooler 4_ with aid of interconnecting tube 450 , where this hot air has arisen as a product of clinker - formed in the rotary kiln 3_ - cooling.

The location of the interconnection tube 450 mouth can be advantageously chosen so, that the temperature of hot air would differ in this place not excessively from the temperature of hot gases, flowing into the interconnecting tube 130 from the output chamber 30_ of rotary kiln 3_ after passing through the both previous cyclones - the lower cyclone 11 and the second cyclone 12 . The connection location is chosen advantageously so that the temperatures of both mediums would not differ more then 20%. With exploitation at least a part of hot air arising in the grate cooler 4_ the thermal conditions are considerably improved in this place and so also the thermal balance of vertical pre heater 1_ .

The quantity of additional warm air from the interconnecting tune 450 can be advantageously regulated for instance depending on the momentary working mode of whole equipment by a regulation element 451 , for instance a clack valve. The remaining, not so warm air is removed through the second output 46_ and by to it connected additional interconnecting tube 460 to following process stages.

At realization of precalcination of powdered raw material before its entering to rotary kiln 3_ in the removal tube 110 to this place by mean of the additional tube 60 the hot combustion air is led from the hottest place of grate cooler 4_ , e.g. from its input area 41_ , and in the same time through the input 61_ fuel is added to this place.

In case of construction version, demonstrated with dashed lines in the Fig no.l, a part of hot air is in the same time led from the first output 45_ of grate cooler 4_ by mean of additional branch 453 of interconnecting tube 450 to an other place of vertical pre heater 1_ , whereas its quantity can be set in both branches with the dividing member 452 . At further construction version according tυ Fig no.1 is further possible to separate with aid of interconnecting tube 62_ a part of hot air from the additional tube 60 and to use it for improving the thermal balance of the whole system, and this namely in case when the hot air led out from the first output 45_ would have not the necessary temperature. The quantity of separated hot air can be once more set with the closing member 620 .

The function at construction version according to Fig no.2 is similar. The hot gases, coming out from the output chamber 30 of rotary kiln 3_ are passing consecutively in direction of arrows R hrough the high temperature part 10 , the transferring tube 5_ and the low temperature part 20_ . The powdered raw material is in this case entered to the low temperature part 20_ by mean of the input 7_ in direction of the arrow V_ and after the first heating up with aid of hot gases flowing through the interconnecting tube 230 in direction of arrow R_ is led to the upper cyclone 23_ . Then it passes in direction of the arrows S_ through the system of output tubes 231 and 121 to the upper part of shaft exchanger 21_ and then to its output tube 211 . Through this tube is then led to the interconnecting tube 450 , by which with aid of the hot air stream is led to the lower part of interconnecting tube 130 of high temperature part 10_ , then it passes through this so, as it is described above. Also here the part of hot air - entered from the first output 45_ of grate cooler 4_ - contributes favorably to the thermal balance of whole equipment and additionally this hot air stream is used for transport of pre heated powdered raw material from the low temperature part 20_ . With the regulation element 451 , which is this case located before the mouth of output tube 211 , the streaming mode of hot air and pre heated powdered raw material in the according part of interconnecting tube 450 can be accommodated.

Unlike to the previous version it is at the demonstration embodiment according to Fig no.2 here is exploited also the thermal energy of less hot cooling air from the end part of grate cooler 4_ , where this air is fror^*:. the second output 46_ of the grate cooler 4 led with aid of additional interconnecting tube 460 into the middle part of low lempeialuie pail 20 υf vertical pic healer 1_ , namely lυ llic lυvvci pail υf interconnecting tube 220 . Also in this case is preserved the advantageous construction arrangement, at which the temperature of air entering through the interconnecting tube 460 does not differ to much from the hot gas temperature in the according place of connecting tube 220 . The most cool air is from the grate cooler 4_ led out with the output tube 470 of the third output 47_ .

It is evident, that the object of invention is not limited to the demonstrated example embodiments. The essence of invention is preserved also at application of other versions of pre heaters, for instance at pre heaters with more branches or with other number of heat exchanging stages. Also the number and the connecting places of inputs of additional hot air from the clinker cooling equipment can be different, and similarly the hot air can be led to different places of the powdered raw material pre heater eventually taking into account the temperature of entered air, and this also in connection with the type and construction of applied clinker cooler, which can be of an other version, especially at different type of the produced material, for instance at production of hydraulic lime.

It is evident that in the example embodiments demonstrated types of interconnections, branching and regulation of additional hot air stream can be combined independently on each other in regard to the working, namely thermal regime of the whole system.

The industrial applicability

The construction versions according the invention can be advantageously used at lines for clinker burning, namely at lines with higher capacity and with equipment for precalculation of the raw material before its entering into the rotary kiln.

(Patent claims)

Claims

1. A line for clinker burning - namely for cement clinker - consisting from rotary kiln, to which a clinker air cooler with cooling air input to the cooling area and at least one heated up air output from the cooler is connected and where to this rotary kiln on the front end a pre-heater of powdered raw material, consisting from a system of mutually serially interconnected cyclones eventually in combination with a shaft heat exchanger is situated, characterized in that the at least one output (45) of the clinker cooler (4) is with aid of interconnecting tube (450) ended into at least one from the connecting tubes (120, 130, 140) of the middle part of vertical pre heater (1).

2. A line for clinker burning according to claim 1, characterized in that the interconnecting tube (450) is with aid of dividing member (452) divided into at least two branches (453), from which each is independently ended to one from the connecting tubes (130, 140) of the middle part of vertical pre heater (1).

3. A line for clinker burning according to claim 1 or claim 2, at which the pre heater of powdered raw material divided into two parts - to a high temperature part and to a low temperature part , which are mutually interconnected with a transferring tube, characterized in that the cooler (4) is provided win^ n' one pair of hot air outputs, first output (45) of hot air with higher temperature anu a -.econd output (46) of hot air with lower temperature , where the first output (45) of hot air is with aid of interconnecting tube (450) ended to at least one from the connecting tubes (120, 130, 140) of middle part of high temperature part (10) of vertical pre heater (1) and the second output (46) is with aid of additional interconnecting tube (460) ended to the connecting tube (220) of middle part of low temperature part (20) of vertical pre heater (1).

4. A line for clinker burning according to one of claims 1 to 3, characterized in that the interconnecting tube (450) and/or the additional interconnecting tube (460) are ended to connecting tube (130) of high temperature part (10) of vertical pre heater (1) and/or connecting tube (220) of low temperature part (20) of vertical pre heater (1) in a location, where the temperature of hot gases coming out from the previous stage of vertical pre heater (1) of powdered raw material differs from the temperature of entered hot air maximally up to 20%.

5. A line for clinker burning according to one of claims 1 to 4, characterized in that to the interconnecting tube (450) and/or additional interconnecting tube (460) a regulation element (451) is inserted.

6. A line for clinker burning according to one of claims 1 to 5, characterized in that the removing tube (1 10) of input chamber (30) of rotary kiln (3) into the lower cyclone (1 1) is forming a calcinating channel with input (61) of fuel and with a n additional tube (60) of combustion air, which is connected with the input area (41) of grate cooler (4).

7. A line for clinker burning according to claim 6, characterized in that the additional tube (60) and the interconnecting tube (450) and/or the additional interconnecting tube (460) are mutually connected with aid of a connecting tube (62).

8. A line for clinker burning according to claim 7, characterized in that the connecting tube (62) is provided with a closing member (620).