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Title:
APPARATUS AND METHOD FOR MAKING COAL WATER SLURRY
Document Type and Number:
WIPO Patent Application WO/2016/085691
Kind Code:
A1
Abstract:
An apparatus for making CWS is provided. The apparatus includes a pretreatment device, a microwave generation device and a slurry preparation device. The pretreatment device is for receiving raw coal and a microwave absorbent, crushing the raw coal and mixing the microwave absorbent with the crushed coal. The microwave absorbent includes at least one of fine slags and soot. The microwave generation device is for heating a mixture of the microwave absorbent and the crashed coal from the pretreatment device. The slurry preparation device is for making coal water slurry using the heated mixture of the microwave absorbent and the crushed coal. A method for making CWS is also provided.

Inventors:
YU LIANG (CN)
XUE JUNLI (CN)
LV JING (CN)
BI XIJING (CN)
OPPENHEIM JUDITH PAULINE (US)
Application Number:
PCT/US2015/060870
Publication Date:
June 02, 2016
Filing Date:
November 16, 2015
Export Citation:
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Assignee:
GEN ELECTRIC (US)
International Classes:
C10J3/00; C10L1/32; F23K1/02
Foreign References:
CN103421558A2013-12-04
Other References:
ELEANOR BINNER ET AL: "A Review of Microwave Coal Processing", JOURNAL OF MICROWAVE POWER AND ELECTROMAGNETIC ENERGY, 1 January 2014 (2014-01-01), pages 35 - 60, XP055239739, Retrieved from the Internet [retrieved on 20160108]
SU SHIUNG LAM ET AL: "A Review on Waste to Energy Processes Using Microwave Pyrolysis", ENERGIES, vol. 5, no. 12, 23 October 2012 (2012-10-23), pages 4209 - 4232, XP055239747, DOI: 10.3390/en5104209
Attorney, Agent or Firm:
DIMAURO, Peter, T. et al. (Global Patent Operation3135 Easton Turnpik, Fairfield CT, US)
Download PDF:
Claims:
CLAIMS:

1. An apparatus , compris ing :

a pretreatment device for receiving raw coal and a microwave absorbent, crashing the raw coal and mixing the microwave absorbent with the crushed coal, the microwave absorbent comprising at least one of fine slags and soot;

a microwave generation device for heating a mixture of the microwave absorbent and the crushed coal from the pretreatment device; and

a slurry preparation device for making coal water slurry using the heated mixture of the microwave absorbent and the crushed coal.

2. The apparatus of claim 1, wherein the pretreatment device comprises a crasher.

3. The apparatus of claim 1, wherein the pretreatment device comprises: a crusher for receiving the raw coal and crashing the raw coal; and

a mixer for receiving the microwave absorbent and mixing the microwave absorbent with the crashed coal.

4. The apparatus of claim 1, further comprising a gasifier in fluid communication with the slurry preparation device for gasifying the coal water slurry to provide the fine slags to the pretreatment device.

5. The apparatus of claim 4, wherein the gasifier is configured to gasify the coal water slurry at a temperature of higher than 1100°C.

6. The apparatus of claim 1, wherein a weight of the microwave absorbent is about 1 percent to about 10 percent of a weight of the raw coal.

7. The apparatus of claim 1 , further comprising a drying device for drying the microwave absorbent and providing the dried microwave absorbent to the pretreatment device.

8. The apparatus of claim 1, wherein the raw coal comprises low rank coal.

9. The apparatus of claim 1 , wherein the fine slags comprise about 20 weight percent to about 40 weight percent of carbon.

10. The apparatus of claim 1 , wherein the microwave generation device is configured to heat the mixture of the microwave absorbent and the crushed coal at a temperature of less than 400°C.

11. A method, comprising:

mixing a microwave absorbent with coal, the microwave absorbent comprising at least one of fine slags and soot;

heating a mixture of the coal and the microwave absorbent by microwave; making coal wrater slurry using the heated mixture of the coal and the microwave absorbent.

12. The method of claim 11, further comprising crashing and mixing the coal and the microwave absorbent via a crasher.

13. The method of claim 11, further comprising crashing, via a crusher, the coal and mixing, via a mixer, the microwave absorbent with the crashed coal.

14. The method of claim 11 , further comprising gasifying the coal water slurry to generate the fine slags for the mixing process.

15. The method of claim 14, wherein gasifying the coal water slurry at a temperature of higher than 1100°C.

16. The method of claim 11, wherein a weight of the microwave absorbent is about 1 percent to about 10 percent of a weight of the raw coal.

17. The method of claim 11 , further comprising drying the microwave absorbent before mixing the microwave absorbent with the coal.

18. The method of claim 11, wherein the raw coal comprises low rank coal.

19. The method of claim 11 , wherein the fine slags comprise about 20 weight percent to about 40 weight percent of carbon.

20. The method of claim 11 , wherein the mixture of the microwave absorbent and the crushed coal is heated at a temperature of less than 400°C.

Description:
APPARATUS AND METHOD FOR MAKING COAL WATER SLURRY BACKGROUND

[0001] Embodiments of the disclosure relate generally to an apparatus and a method for making coal water slurry (CWS), and more particularly to an apparatus and a method for making CWS using upgraded coal by microwave.

[0002] In coal gasification fields, two types of methods are usually employed to supply coal to a gasifier for gasification. One is pneumatically transporting pulverized coal with pressurized nitrogen and spraying the coal into a gasifier. Another is preparing slurry of coal and water, which hereinafter is referred to as "coal water slurry" or "CWS," and supplying the CWS to a gasifier. The "CWS" method has been widely used because it is more reliable and more readily adaptable to a higher gasification pressure than the method employing coal in a dry state.

[0003] As used herein CWS concentration refers to the concentration of coal in the slurry. Generally, higher CWS concentration leads to higher gasification efficiency and lower consumption of coal and oxygen. Thus, during preparation, it is desirable to have higher CWS concentration of the CWS so as to economically gasify the CWS. In some conventional embodiments, the CWS concentration may not be as high as desirable in the CWS, especially when low rank coal is used.

[0004] It is desirable to provide a solution to address at least one of the above- mentioned problems.

BRIEF DESCRIPTION

[0005] An apparatus for making CW r S is provided. The apparatus includes a pretreatment device, a microwave generation device and a slurry preparation device. The pretreatment device is for receiving raw coal and microwave absorbent, crushing the raw coal and mixing the microwave absorbent with the crushed coal. The microwave absorbent includes at least one of fine slags and soot. The microwave generation device is for heating a mixture of the microwave absorbent and the crushed coal from the pretreatment device. The slurry preparation device is for making coal water slurry using the heated mixture of the microwave absorbent and the crushed coal.

[0006] A method for making CWS is provided. The method includes mixing microwave absorbent with coal. The microwave absorbent includes at least one of fine slags and soot. The method further includes heating a mixture of the coal and the microwave absorbent by microwave. And the method includes making coal water slurry using the heated mixture of the coal and the microwave absorbent.

DRAWINGS

[0007] These and other features and aspects of embodiments of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[0008] FIG. 1 is a schematic view of an apparatus for making CWS according to one embodiment;

[0009] FIG. 2 is a schematic view of the apparatus for making CWS according to another embodiment;

[0010] FIG. 3 is a schematic view of the apparatus for making CWS according to another embodiment;

[0011] FIG. 4 is a schematic view of the apparatus for making CWS according to another embodiment;

[0012] FIG. 5 is a schematic view of the apparatus for making CWS according to another embodiment;

[0013] FIG. 6 is a flow chart of a method for making CWS according to an embodiment; and [0014] FIG. 7 is an experimental diagram illustrating comparison of a moisture content of coal without fine slags after microwave treatment and a moisture content of coal with fine slags after microwave treatment.

DETAILED DESCRIPTION

[0015] Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which this invention belongs. The terms "a" and "an" do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. Moreover, the terms "coupled" and "connected" are not intended to distinguish between a direct or indirect coupling/connection between two components. Rather, such components may be directly or indirectly coupled/connected unless otherwise indicated. Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as "about," is not to be limited to the precise value specified. Additionally, when using an expression of "about a first value - a second value," the about is intended to modify both values. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value or values.

[0016] FIG. I illustrates a schematic view of an apparatus 10 for making CWS according to one embodiment. As used herein, the term "CWS" may indicate a mixture of certain amounts of coal, water and additives for producing energy used in generating electricity, heating, support processing, and manufacturing for example. In recent years, use of CWS has become an alternative to use of conventional fuel oil and coal.

[0017] Typically, the CWS may comprise from about 55wt% to about 70wt% of coal particles, from about 30wt% to about 45wt% of water, and less than about lwt% of additive. It should be noted that embodiments of the invention are not limited to any particular type of coal or additives for the CWS. Non-limiting examples of additives include alkylnaphtheiene sulfonate and polyoxyalkylene alkyl ether. In some embodiments, the additive can be omitted if desired.

[0018] The apparatus 10 can prepare high concentration CWS 18 from low rank coal 11. The low rank coal (LRC) is one kind of coal whose coal rank is lower than bituminous coal which mainly includes sub-bituminous coal and lignite for example. Since the cost of low rank coal is lower, it may be cost-effective to produce the CWS having higher CWS concentration using the low rank coal. In the illustrated embodiment, the apparatus 10 includes a crusher 12, a microwave oven 14, and a slurry preparation device 16.

[0019] The crusher 12 serves as a pretreatment device for receiving raw coal 1 1 and a microwave absorbent 22, crushing the raw coal 11 and mixing the microwave absorbent 22 with the crushed coal. The crusher 12 crushes the raw low rank coal 11 into appropriate particle sizes according to manufacture needs. In this embodiment, the crusher 12 also mixes uniformly the microwave absorbent 22 and the raw coal 1 1 during crashing. The microwave absorbent 22 is added into the coal 1 1 to improve energy efficiency of microwave treatment in the microwave oven 14. A weight of the microwave absorbent 22 added into the raw coal 1 1 is about 1 percent to about 10 percent of a weight of the raw coal 11.

[0020] The microwave absorbent 22 includes at least one of fine slags and soot, i.e. the microwave absorbent 22 includes the fine slags, the soot or a combination of the fine slags and the soot. The fine slags are byproducts of coal gasification at a high temperature of higher than 1 100°C. The fine slags, in one embodiment, include about 20 weight percent to about 40 weight percent of carbon. In one embodiment, the fine slags also include inorganic salts, such as silicon dioxide. In one embodiment, the fine slags may be obtained from a coal gasification plant (not shown). The soot is a byproduct of gasification of oil or natural gas at a high temperature of higher than 1 100°C. The soot is impure carbon particles resulting from the incomplete combustion of hydrocarbons. Carbon atom in the fine slags and the soot are changed due to the high temperature in the gasification such that the fine slags and the soot have high absorption capacity for microwave. And the fine slags and the soot are obtained easily and are very cheap.

[0021] In the illustrated embodiment, the microwave oven 14 is configured to heat a mixture 24 of the microwave absorbent 22 and the crushed coal from the crusher 12. In another embodiment, any other microwave generation device may be employed to generate microwave to irradiate the mixture 24 to remove most of water and part of carbon dioxide (CO 2 ). The microwave generation device 14 is configured to heat the mixture 24 of the microwave absorbent 22 and the crushed coal at a temperature of less than 400°C, The mixture 24 is heated via the microwave generation device 14 at a relative low temperature. The energy efficiency of microwave treatment in the microwave oven 14 is improved due to the microwave absorbent 22. Nitrogen is introduced into the microwave oven 14 during microwave treatment. After being treated by the microwave oven 14, it is expected that the low rank coal 1 1 may be improved in a manner such as having a reduced oxygen and carbon (O/C) ratio, a decreased inherent moisture, smoothed particle shapes, and/or modified surface properties of the particles, for example. Such improvements are expected to increase CWS concentration of the produced CWS 18.

[0022] The slurry preparation device 16 is for making the CWS 18 using the heated mixture 26 of the microwave absorbent 22 and the crushed coal from the microwave oven 14. The heated mixture 26 with low moisture is introduced into the slurry preparation device 16 to make the high concentration CWS 18. In one embodiment, the slurry preparation device 16 may grind the heated mixture 26 with water in a rod mill to prepare the CWS 18.

[0023] FIG. 2 illustrates a schematic view of an apparatus 20 for making CWS according to another embodiment. The apparatus 20 in FIG. 2 is similar to the apparatus 10 in FIG. 1. Comparing with the apparatus 10 in FIG. 1, the apparatus 20 in FIG. 2 further includes a drying device 28 for drying the microwave absorbent 22 and providing the dried microwave absorbent 31 to the crusher 12. The drying device 28 is configured to remove water from the microwave absorbent 22 to provide the dried microwave absorbent 31 with low moisture. [0024] FIG. 3 illustrates a schematic view of an apparatus 30 for making CWS according to another embodiment. The apparatus 30 in FIG. 3 is similar to the apparatus 10 in FIG. 1. Comparing with the apparatus 10 in FIG. 1, the apparatus 30 in FIG. 3 further includes a gasifier 21 in fluid communication with the slurry preparation device 16 for gasifying the CWS 18 to provide fine slags 32 to the pretreatment device 12. The gasifier 21 is configured to gasify the CWS 18 at a temperature of higher than 1 100°C. The gasifier 21 gasifies the CWS and generates syngas 34 and the fine slags 32. The fine slags 32 are byproducts of the gasification, which are added into the coal 11 as microwave absorbent. In the illustrated embodiment, the microwave absorbent 22, for example fine slags, provided by any other gasification plant are added into the crusher 1 1 in the beginning of preparing CWS process, and then the fine slags 32 are generated in the gasifier 21. The fine slags 32 are recycled. A total weight of the microwave absorbent 22 and the fine slags 32 mixed with the raw coal 11 is about 1 percent to about 10 percent of a weight of the raw coal 1 1.

[0025] FIG. 4 illustrates a schematic view of an apparatus 40 for making CWS according to another embodiment. The apparatus 40 in FIG. 4 is similar to the apparatus 10 in FIG. 1. Comparing with the apparatus 10 in FIG. 1, the apparatus 40 in FIG. 4 includes a crusher 12 and a mixer 36. The crusher 12 and the mixer 36 serve as a pretreatment device 38 for receiving the raw coal 1 1 and the microwave absorbent 22, crushing the raw coal 11 and mixing the microwave absorbent 22 and the crushed coal during crushing. The crusher 12 in the illustrated embodiment operates in a similar manner with the crusher 12 in FIG. 1. The crusher 12 is for receiving the raw coal 1 1 and crushing the raw coal 1 1. The mixer 36 is for receiving the microwave absorbent 22 and mixing the microwave absorbent 22 with the crashed coal 42. The microwave absorbent 22 and the crashed coal 42 are mixed intensively in the mixer 36, such as a vessel. In one embodiment, the mixer 36 is put into the microwave oven 14 after mixing.

[0026] FIG. 5 illustrates a schematic view of an apparatus 50 for making CWS according to another embodiment. The apparatus 50 in FIG. 5 is similar to the apparatus 40 in FIG. 4. Comparing with the apparatus 40 in FIG. 4, the apparatus 50 in FIG. 5 further includes a gasifier 21 which operates in a similar manner with the gasifier 21 in FIG. 3. The gasifier 21 is configured to generate the fine slags 32 using the CWS 18 and provide the fine slags 32 into the mixer 36. The fine slags 32 are mixed with the crushed coal 42 in the mixer. In one embodiment, the microwave absorbent 22 provided by any other coal gasification plant may also be introduced into the mixer 36.

[0027] FIG. 6 illustrates a flow chart of a method 60 for making CWS according to an embodiment. The method 60 includes mixing a microwave absorbent with coal. The microwave absorbent includes at least one of fine slags and soot. The fine slags and the soot have high absorption capacity for microwave. The fine slags include about 20 weight percent to about 40 weight percent of carbon. A weight of the microwave absorbent is about 1 percent to about 10 percent of a w r eight of the raw r coal. In the illustrated embodiment, in block 61 , a raw coal is crashed into appropriate particle sizes according to manufacture needs, and in block 63, fine slags are mixed with the crashed coal. In one embodiment, the raw coal and the fine slags are crushed and mixed simultaneously via a crusher. In another embodiment, the raw coal is crushed via the crasher and the fine slags are mixed with the crashed coal via a mixer. In one embodiment, the fine slags are dried before mixing the fine slags with the coal. In one embodiment, the raw coal includes low rank coal.

[0028] In block 65, the mixture of the coal and the microwave absorbent are heated by microwave. The mixture of the microwave absorbent and the crashed coal is heated at a temperature of less than 400°C. Most of water and part of CO 2 is removed in microwave treatment. The energy efficiency of microwave treatment is improved due to the microwave absorbent. In block 67, CWS is made using the heated mixture of the coal and the microwave absorbent from the block 65. In one embodiment, the microwave absorbent are provided by any other gasification plant. In the illustrated embodiment, the method 60 further includes block 69. In block 69, the CWS is gasified to generate the syngas and the fine slags. The fine slags are provided to the mixing process in block 63. The fine slags can be recycled. The CWS is gasified at a temperature of higher than 1 100°C. [0029] FIG. 7 is an experimental diagram illustrating comparison of a moisture content of coal without fine slags after microwave treatment and a moisture content of coal with fine slags after microwave treatment. In this experimentation, a first sample is a mixture of 15g coal and 1 .5g fine slags. The weight ratio of coal weight to fine slag weight is 10: 1. And a second sample is 16.5g coal without the fine slags. The coals in the first sample and the second sample both are Xijing coal having a particle size of less than 1 mm and have a moisture content of 24.77%. The fine slags are sampled from a coal gasification plant. In order to avoid the effect of moisture in the fine slags on the experimentation, the fine slags are dried at 100°C. The moisture content in the fine slags is 1.38% after drying.

[0030] In this experimentation, the first sample and the second sample are respectively loaded into vessels positioned in a microwave oven. Nitrogen (N 2 ) is introduced into the vessels. Power of the microwave oven is set to 190W and irradiation time is adjusted to 3, 6, 9, 12 minutes respectively to measure the moisture contents of the first sample and the second sample.

[0031] As illustrated in FIG. 7, line 72 illustrates the moisture content of the coal without the fine slags in the second sample after microwave treatment. Line 74 illustrates the moisture content of the coal in the mixture after microwave treatment. The moisture content of the mixture (i.e. the first sample) decreases after the dry fine slags are added into the coal since the moisture content of the dry fine slags is much less than the moisture content of the coal. The moisture content of the coal on the line 74 is calculated based on the measured moisture content of the mixture and a decreased moisture content by adding the dry fine slags.

[0032] As can be seen from comparison of the lines 72 and 74, the moisture content of the coal in the mixture is lower than the moisture content of the coal without the fine slags after microwave treatment in the same irradiation time. The moisture in the coal in the mixture is reduced by about 2% comparing with the moisture in the coal without the fine slags after 6-min's microwave treatment. It spends less irradiation time to microwave irradiate the coal with the fine slags than the coal without the fine slags to get same moisture contents of the coals in the first sample and the second sample. Addition of the fine slags reduces the irradiation time largely to achieve the same moisture content with the moisture content of the coal without the fine slags, especially when the moisture content is low, for example lower than 7% in the diagram. Accordingly, the energy consumption of the microwave treatment is obviously reduced by adding the fine slags, and thus, the energy efficiency of is improved.

[0033] In this experimentation, the microwave power is only 190 W. The energy efficiency improvement could be more obvious at higher microwave power. The soot has similar structures of carbon atoms with the fine slags such that the soot also has high capability of microwave absorption.

[0034] While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.