Manufacturing facility for quicklime, and manufacturing facility and manufacturing process for slaked lime

Abstract

A manufacturing facility for quicklime is provided, which can manufacture highly active quicklime by a simple manufacturing facility, and which can also separate and recover, in a high concentration, CO.sub.2 gas generated at the time of manufacturing quicklime. The manufacturing facility for quicklime is configured by including: a regenerative calciner 11 which has a supply port 11a for supplying granular limestone C into the regenerative calciner 11, heating means capable of maintaining the temperature of the atmosphere in the regenerative calciner 11 at a temperature not less than the calcination temperature of the limestone, an exhaust pipe 15 connected to an upper part of the regenerative calciner 11 so as to discharge combustion exhaust gas of the heating means and CO.sub.2 gas generated by the calcination of limestone, and a discharge port 14 for taking out quicklime produced by the calcination; and a heat medium 16 which has a particle diameter larger than the particle diameter of the limestone and which is filled in the regenerative calciner 11.

Claims

1. A facility for manufacturing slaked lime, the facility comprising: an apparatus for manufacturing quicklime, comprising (i) a regenerative calciner comprising a supply port configured to supply granular limestone into the regenerative calciner, a heater configured to maintain temperature of an atmosphere in the regenerative calciner at a temperature not less than a calcination temperature of the granular limestone, an exhaust pipe connected to an upper part of the regenerative calciner and configured to discharge combustion exhaust gas from the heater and CO.sub.2 gas generated by calcination of the granular limestone, a three-way selector valve connected to the exhaust pipe such that the three-way selector valve is positioned between the upper part of the regenerative calciner and a heat exchanger, and a discharge port configured to remove quicklime produced by the calcination therefrom, and (ii) a heat medium having a particle diameter larger than a particle diameter of the granular limestone, the heat medium being filled in the regenerative calciner, a slaking machine configured to produce slaked lime by supplying slaking water to quicklime manufactured in the apparatus; an aging machine configured to age the slaked lime discharged from the slaking machine; a drying machine configured to dry the slaked lime comprising water and aged in the aging machine; and the heat exchanger configured to supply, as a heat source of the drying machine, steam generated by heat exchange between water and the combustion exhaust gas or the CO.sub.2 gas discharged from the exhaust pipe of the apparatus, wherein a first discharge side port of the three-way selector valve is connected to a first transfer pipe, a second discharge side port of the three-way selector valve is connected to a second transfer pipe, and the first transfer pipe and the second transfer pipe are connected to the heat exchanger and configured to respectively feed the combustion exhaust gas and the CO.sub.2 gas to the heat exchanger.

2. The facility according to claim 1, wherein the heat medium is quicklime.

3. The facility according to claim 1, further comprising a buffer tank configured to temporarily store the quicklime removed from the discharge port, wherein the buffer tank is positioned between the apparatus and the slaking machine.

4. A manufacturing process, comprising: manufacturing slaked lime with the facility according to claim 1; and recovering the CO.sub.2 gas having passed through the heat exchanger.

5. The facility according to claim 1, wherein the heat exchanger comprises a heat source discharge pipe and a second three-way selector valve connected to the heat source discharge pipe.

6. The facility according to claim 5, wherein a first discharge side port of the second three-way selector valve is connected to a first discharge pipe, and a second discharge side port of the second three-way selector valve is connected to a second discharge pipe.

7. The facility according to claim 1, wherein the facility comprises a plurality of the apparatus.

8. The facility according to claim 1, wherein the granular limestone has a diameter of from 10 m to 1 mm.

9. A facility for manufacturing slaked lime, the facility comprising: an apparatus for manufacturing quicklime, comprising (i) a regenerative calciner comprising a supply port configured to supply granular limestone into the regenerative calciner, a heater configured to maintain temperature of an atmosphere in the regenerative calciner at a temperature not less than a calcination temperature of the granular limestone, an exhaust pipe connected to an upper part of the regenerative calciner and configured to discharge combustion exhaust gas from the heater and CO.sub.2 gas generated by calcination of the granular limestone, a three-way selector valve connected to the exhaust pipe, and a discharge port configured to remove quicklime produced by the calcination therefrom, and (ii) a heat medium having a particle diameter larger than a particle diameter of the granular limestone, the heat medium being filled in the regenerative calciner; a slaking machine configured to produce slaked lime by supplying slaking water to quicklime manufactured in the apparatus; an aging machine configured to age the slaked lime discharged from the slaking machine; a drying machine configured to dry the slaked lime comprising water and aged in the aging machine; and a heat exchanger configured to supply, as a heat source of the drying machine, steam generated by heat exchange between water and the combustion exhaust gas or the CO.sub.2 gas discharged from the exhaust pipe of the apparatus, wherein a first discharge side port of the three-way selector valve is connected to a first transfer pipe, a second discharge side port of the three-way selector valve is connected to a second transfer pipe, and the first transfer pipe and the second transfer pipe are connected to the heat exchanger and configured to respectively feed the combustion exhaust gas and the CO.sub.2 gas to the heat exchanger.

10. A manufacturing process for producing slaked lime, comprising: manufacturing slaked lime with the facility according to claim 9; and recovering the CO.sub.2 gas having passed through the heat exchanger.

11. The facility according to claim 9, wherein the heat exchanger comprises a heat source discharge pipe and a second three-way selector valve connected to the heat source discharge pipe.

12. The facility according to claim 11, wherein a first discharge side port of the second three-way selector valve is connected to a first discharge pipe, and a second discharge side port of the second three-way selector valve is connected to a second discharge pipe.

13. The facility according to claim 9, wherein the heat medium is quicklime.

14. The facility according to claim 9, further comprising a buffer tank configured to temporarily store the quicklime removed from the discharge port, wherein the buffer tank is positioned between the apparatus and the slaking machine.

15. The facility according to claim 9, wherein the facility comprises a plurality of the apparatus.

16. The facility according to claim 9, wherein the granular limestone has a diameter of from 10 m to 1 mm.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a view showing a schematic configuration of an embodiment of a manufacturing facility for slaked lime according to the present invention.

(2) FIG. 2 is a longitudinal sectional view schematically showing an embodiment of a manufacturing facility for quicklime according to the present invention.

(3) FIG. 3 is a longitudinal sectional view schematically showing a modification of FIG. 2.

(4) FIG. 4 is a longitudinal sectional view schematically showing another embodiment of the manufacturing facility for quicklime according to the present invention.

(5) FIG. 5 is a view showing a schematic configuration of a conventional manufacturing facility for quicklime.

DESCRIPTION OF EMBODIMENTS

(6) FIG. 1 and FIG. 2 show an embodiment of a manufacturing facility for quicklime according to the present invention, and an embodiment of a manufacturing facility for slaked lime using the manufacturing facility for quicklime. Reference numeral 10 in FIG. 1 and FIG. 2 denotes a manufacturing facility for quicklime, and reference numeral 11 denotes a regenerative calciner which is a main portion of the manufacturing facility for quicklime.

(7) The regenerative calciner 11 is a horizontal furnace configured such that a supply port 11a for supplying, to the inside of the furnace, limestone C crushed into particles having a particle diameter of 10 m to 1 mm is provided at an upper part of the regenerative calciner 11, and such that a burner (heating means: not shown) capable of maintaining the temperature of the atmosphere in the regenerative calciner 11 at a temperature not less than the calcination temperature of the limestone (for example, about 900 C.) is provided at a lower part of the regenerative calciner 11.

(8) Further, a fuel pipe 12 and an air pipe 13, which respectively supply fuel and combustion air, are connected to each of one or more burners provided at a bottom part of the regenerative calciner 11.

(9) On the other hand, a discharge port 14 for taking out powdery quicklime produced by the calcination is provided at the side wall of the regenerative calciner 11 and at a predetermined height position from the bottom part of the regenerative calciner 11. An exhaust pipe 15 for discharging combustion exhaust gas of the burner or CO.sub.2 gas generated by the calcination of limestone is connected to a ceiling part of the regenerative calciner 11.

(10) Further, a heat medium 16 is filled in the regenerative calciner 11. As the heat medium 16, quicklime having a particle diameter larger than the particle diameter of the limestone C which is supplied into the regenerative calciner 11 is used.

(11) Further, a buffer tank 17 for temporarily storing the quicklime taken out from the discharge port 14 via an overflow pipe 14a, a slaking machine 18, an aging machine 19 for aging the slaked lime discharged from the slaking machine 18, and a drying machine 20 for drying the slaked lime aged in the aging machine 19 and containing water are successively arranged at the subsequent stage of the quicklime manufacturing facility 10 configured as described above.

(12) Here, the slaking machine 18, the aging machine 19, and the drying machine 20 are known apparatuses used in a general manufacturing facility for slaked lime. That is, in the slaking machine 18, slaked lime is produced in such a manner that slaking water consisting of cold water containing an additive, such as ethylene glycol, a diethylene glycol, and glycerin, is supplied from a slaking water feed line (not shown) to the quicklime which is charged into the slaking machine 18 by a fixed amount at each charging operation via a hopper 18a from a discharge pipe 17a of the buffer tank 17, and that the slaking water and the quicklime are stirred to be mixed with each other.

(13) Further, in the aging machine 19, the slaked lime produced by slaking reaction in the slaking machine 18 and containing water is aged while being stirred. In the drying machine 20, the slaked lime aged in the aging machine 19 is dried while being stirred, and thereby the water contained in the slaked lime is removed. Then, the slaked lime discharged from the drying machine 20 is pulverized and classified, so that slaked lime having a predetermined particle size is obtained as a product.

(14) Further, the manufacturing facility for slaked lime is provided with an exhaust heat boiler (heat exchange means) 21 which generates steam by using, as a heating source, the exhaust gas or the CO.sub.2 gas discharged from the regenerative calciner 11 of the manufacturing facility 10 for quicklime, and which supplies the generated steam to the drying machine 20 as steam for drying. That is, a three-way selector valve 22 is connected to the exhaust pipe 15 of the regenerative calciner 11, and a transfer pipe 23 of combustion exhaust gas and a transfer pipe 24 of CO.sub.2 gas are respectively connected to the two discharge side ports of the three-way selector valve 22.

(15) Further, the transfer pipe 23 of combustion exhaust gas and the transfer pipe 24 of CO.sub.2 gas are respectively connected to the heat source supply side of the exhaust heat boiler 21. Further, a three-way selector valve 26 is also connected to a heat source discharge pipe 25 of the exhaust heat boiler 21. A discharge pipe 27 of combustion exhaust gas and a discharge pipe 28 of CO.sub.2 gas are respectively connected to the two discharge side ports of the three-way selector valve 26. Note that it is also possible to configure such that the exhaust pipe 15 of the regenerative calciner 11 is directly connected to the exhaust heat boiler 11 without using the three-way selector valve 22, the transfer pipe 23 of combustion exhaust gas, and the transfer pipe 24 of CO.sub.2 gas, and such that the discharge pipe 27 of combustion exhaust gas and the discharge pipe 28 of CO.sub.2 gas are switched only by the three-way selector valve 26.

(16) On the other hand, a steam supply pipe 30 is connected between the exhaust heat boiler 21 and the drying machine 20, the steam supply pipe 30 being configured to supply, to the drying machine 20, the steam as a heat source, which steam is generated in the exhaust heat boiler 21 by evaporating water supplied from a water supply pipe 29 by the heat of the combustion exhaust gas or the CO.sub.2 gas supplied from the transfer pipe 24 or the transfer pipe 25.

(17) Next, there will be described an embodiment of a manufacturing process for slaked lime according to the present invention using the slaked-lime manufacturing facility configured as described above.

(18) First, in the regenerative calciner 11 of the manufacturing facility for quicklime, fuel and combustion air are supplied to the burner provided at the bottom part of the regenerative calciner 11 from the fuel pipe 12 and the air pipe 13, and the heat medium 16 in the regenerative calciner 11 is heated to a temperature not less than the calcination temperature of limestone C (for example, 1200 C.), so as to store heat in the regenerative calciner 11. Further, the combustion exhaust gas discharged at this time is supplied, as a heat source, to the exhaust heat boiler 21 from the exhaust pipe 15 via the three-way selector valve 22 and the transfer pipe 23 of combustion exhaust gas. Note that the combustion exhaust gas, the temperature of which is lowered by the heat exchange in the exhaust heat boiler 21, is discharged from the heat source discharge pipe 25 via the three-way selector valve 26 and the discharge pipe 27 of combustion exhaust gas.

(19) Then, in a state where the atmosphere in the regenerative calciner 11 is held at a temperature not less than the calcination temperature of limestone C, the three-way selector valve 22 is switched so as to communicate with the CO.sub.2 transfer pipe 24, and granular limestone C is supplied to the inside of the regenerative calciner 11 from the supply port 11a, so as to be heated to a temperature not less than the calcination temperature (for example, 900 C.) by the heat medium 16 in the regenerative calciner 11. As a result, a chemical reaction as represented by the formula: CaCO.sub.3.fwdarw.CaO+CO.sub.2 is caused, so that quicklime is produced and CO.sub.2 gas is generated.

(20) The CO.sub.2 gas generated in the regenerative calciner 11 is supplied, as a heat source, to the exhaust heat boiler 21 from the exhaust pipe 15 via the three-way selector valve 22 and the transfer pipe 24 of CO.sub.2 gas. Then, the CO.sub.2 gas, the temperature of which is lowered by heat exchange with water in the exhaust heat boiler 21, is recovered as high-concentration CO.sub.2 gas via the discharge pipe 28 of CO.sub.2 gas from the three-way selector valve 26 switched to the discharge pipe 28 of CO.sub.2 gas.

(21) In this way, the combustion exhaust gas or the CO.sub.2 gas is supplied, as a heat source, to the exhaust heat boiler 21. Thereby, steam is generated from water continuously supplied from the supply pipe 29 in the exhaust heat boiler 21, and the generated steam is supplied to the drying machine 20 from the steam supply pipe 30.

(22) On the other hand, the quicklime produced in the regenerative calciner 11 is fluidized by the CO.sub.2 gas generated at the time of calcination. The fluidized quicklime is made to overflow from the overflow pipe 14a and is sent to the buffer tank 17 so as to be temporarily stored in the buffer tank 17.

(23) The quicklime stored in the buffer tank 17 is charged into the slaking machine 18 from the discharge pipe 17a via the hopper 18a by a fixed amount at each charging operation, and slaking water supplied from a slaking water feed line (not shown) is added and stirred into the quicklime. As a result, a chemical reaction as represented by the formula: CaO+H.sub.2O.fwdarw.Ca (OH).sub.2 is caused, so that slaked lime is produced.

(24) After the slaked lime produced by the slaking reaction in the slaking machine 18 is sent to the aging machine 19 and aged in the aging machine 19, the slaked lime is dried in the drying machine 20 by the steam supplied from the exhaust heat boiler 21 and is then discharged from the drying machine 20.

(25) As described above, according to the quicklime manufacturing facility 10 configured as described above, and the slaked-lime manufacturing facility provided with the quicklime manufacturing facility 10, and according to the slaked-lime manufacturing process using the manufacturing facilities, it is possible that the limestone C is supplied from the supply port 11a in a state where the heat medium 16 filled in the regenerative calciner 11 is heated by the burner to a temperature not less than the calcination temperature of limestone so as to maintain the temperature of the atmosphere in the regenerative calciner 11 at a temperature not less than the calcination temperature, and that CO.sub.2 gas generated by the calcination of the limestone C and having a concentration of about 100% is recovered via the transfer pipe 24 and the exhaust heat boiler 21 from the discharge pipe 28 of the exhaust heat boiler 21.

(26) At this time, the limestone C is heated and calcined in the regenerative calciner 11 by the heat medium 16 having a particle diameter larger than the particle diameter of the limestone C and hence having an extremely small specific surface area. Thereby, a large amount of heat can be stored in the regenerative calciner 11. Also, even when the heat medium 16 is heated to a temperature not less than the calcination temperature of the limestone C, that is, to a temperature not less than 1000 C. in the regenerative calciner 11, sticking and fusion between the particles of the heat medium 16, and sticking and fusion between the particle of the heat medium 16 and the furnace wall are suppressed, so that the occurrence of a coating trouble and the like can be suppressed.

(27) Further, since the heat medium 16 having a particle diameter larger than the particle diameter of the limestone C is used, it is possible that the produced powdery quicklime is fluidized by the CO.sub.2 gas generated at the time of calcination described above, and that the fluidized quicklime is made to overflow from the regenerative calciner 11 so as to be simply taken out from the regenerative calciner 11.

(28) Further, since quicklime is used as the heat medium 16, the heat medium 16 has a melting point as high as about 2500 C., and hence particles of the heat medium 16 are hardly fused to each other. Also, no adverse effect is caused even in the case where, while the calcination of the limestone C is repeated in the regenerative calciner 11 by using quicklime as the heat medium 16, fine powder is generated as a result of gradual abrasion of the quicklime.

(29) In addition, steam used as a heat source of the drying machine 20 is obtained by sending, to the exhaust heat boiler 11, high-temperature combustion exhaust gas and high-temperature and high-concentration CO.sub.2 gas which are discharged from the manufacturing facility for quicklime, and hence high thermal efficiency and excellent economic efficiency can be obtained.

(30) FIG. 3 shows a modification of the manufacturing facility for quicklime configured as described above. In this manufacturing facility, a burner for heating the inside of a regenerative calciner 31 is provided at one of the lower side surfaces of the regenerative calciner 31, and a fuel pipe 32 and an air pipe 33 for respectively supplying fuel and combustion air are connected to the burner.

(31) Further, a transfer pipe 34 for discharging combustion exhaust gas generated at the time of heating the heat medium 16 and storing heat in the regenerative calciner 31 is provided at the other of the lower side surfaces of the regenerative calciner 31. The transfer pipe 34 is directly connected to the heat source supply side of the exhaust heat boiler 21. On the other hand, a transfer pipe 35 for discharging CO.sub.2 gas generated in the regenerative calciner 31 is provided at a ceiling part of the regenerative calciner 31. The transfer pipe 35 is directly connected to the heat source supply side of the exhaust heat boiler 21. Note that, in FIG. 3, reference numeral 36 denotes a supply port of granular limestone C, and reference numeral 37 denotes a discharge port of quicklime generated in the regenerative calciner 31.

(32) Therefore, in the quicklime manufacturing facility configured as described above, the combustion exhaust gas generated at the time of storing heat is directly sent to the exhaust heat boiler 21 from the transfer pipe 34, and the CO.sub.2 gas generated at the time of calcination of the limestone C is directly sent, as a heat medium, to the exhaust heat boiler 21 from the transfer pipe 35. Further, quicklime generated in the regenerative calciner 31 is fluidized by the CO.sub.2 gas generated at the time of calcination of the limestone C. The fluidized quicklime is made to overflow from the discharge port 37 and is sent to the buffer tank 17 so as to be temporarily stored in the buffer tank 17.

(33) FIG. 4 shows another embodiment of the manufacturing facility for quicklime according to the present invention. This manufacturing facility is provided with a vertical type regenerative calciner 41 in which the same heat medium 16 is filled.

(34) A burner, to which a supply pipe 42 for supplying fuel is connected, is provided at a lower side surface of the regenerative calciner 41, and a supply pipe 43 of combustion air is provided at a bottom part of the regenerative calciner 41. Further, a supply port 44 for introducing granular limestone C is provided at one of the side surfaces of the regenerative calciner 41.

(35) Further, a discharge pipe 45 for discharging combustion exhaust gas or CO.sub.2 gas in the regenerative calciner 41 is provided at a ceiling part of the regenerative calciner 41, and a cyclone 46 is provided at the outlet side of the discharge pipe 45. Further, an exhaust gas pipe 47 for exhausting combustion exhaust gas or CO.sub.2 gas is provided at a ceiling part of the cyclone 46, and the three-way selector valve 22 described above is connected to the exhaust gas pipe 47.

(36) On the other hand, a discharge port 48 for extracting quicklime C, from which CO.sub.2 gas generated at the time of calcination has been separated, is provided at a bottom part of the cyclone 46. The quicklime C discharged from the discharge port 48 is charged into the buffer tank 17 described above.

(37) In the quicklime manufacturing facility configured as described above, the CO.sub.2 gas, which is generated when the limestone C supplied from the supply port 44 is calcined by the heat medium 16, is introduced into the cyclone 46 from the discharge pipe 45 together with the produced quicklime C. Then, the CO.sub.2 gas and the quicklime C are separated from each other in the cyclone 46. Further, the separated quicklime C is discharged from the discharge port 48 provided at the bottom part of the cyclone 46 and is charged into the buffer tank 17. On the other hand, the CO.sub.2 gas separated in the cyclone 46 is similarly supplied, as a heat medium, to the exhaust heat boiler 21 via the three-way selector valve 22 from the exhaust gas pipe 47 provided at the ceiling part of the cyclone 46.

(38) Therefore, also with the quicklime manufacturing facility using one of the regenerative calciners 31 and 41, and with the slaked-lime manufacturing facility and process each using the quicklime manufacturing facility, the same operation effects can be obtained.

INDUSTRIAL APPLICABILITY

(39) The present invention can be used for recovering, in a high concentration, CO.sub.2 gas generated at the time of producing quicklime and slaked lime, and can be used for recovering, in a high concentration, CO.sub.2 gas generated at the time of producing of quicklime.

REFERENCE SIGNS LIST

(40) 11, 31, 41 Regenerative calciner

(41) 11a, 36, 44 Supply port of limestone

(42) 14, 37, 48 Discharge port of quicklime

(43) 15, 45 Exhaust pipe

(44) 16 Heat medium

(45) 17 Buffer tank

(46) 18 Slaking machine

(47) 19 Aging machine

(48) 20 Drying machine

(49) 21 Exhaust heat boiler (Heat exchange means)

(50) C Limestone

(51) C Quicklime