AU2013374015B2

AU2013374015B2 - Powdered solid fuel boiler equipped with regenerative rotating commutating heater

Info

Publication number: AU2013374015B2
Application number: AU2013374015A
Authority: AU
Inventors: Lin Chen; Guangming Lu; Daping SHEN; Shengmei WANG; Daohong WU; Yulin Wu
Original assignee: Beijing Shenwu Environmental and Energy Technology Co Ltd
Current assignee: Beijing Shenwu Environmental and Energy Technology Co Ltd
Priority date: 2013-01-18
Filing date: 2013-05-16
Publication date: 2016-03-03
Anticipated expiration: 2033-05-16
Also published as: ZA201505205B; WO2014110882A1; AU2013374015A1; RU2622139C2; RU2015133246A

Abstract

A powdered solid fuel boiler equipped with a regenerative rotating commutating heater comprises a hearth, a regenerative rotating commutating heater, a fume passage, and an air passage. An inlet end of the fume passage is communicated with a top portion of the hearth, and an outlet end of the fume passage is communicated with the regenerative rotating commutating heater. The regenerative rotating commutating heater comprises heat carriers which are respectively accommodated in accommodating portions. The heat carriers are made of non-metallic solid materials, and are provided with denitration catalyst layers. The air passage is used for delivering air at least into the other one of the paired accommodating portions.

Description

PULVERIZED SOLID FUEL BOILER INSTALLED WITH ROTARY-TYPE REGENERATIVE HEATER FIELD The present invention relates to the field of heat exchange, and more particularly to a pulverized solid fuel boiler installed with a rotary-type regenerative heater. BACKGROUND A rotary air preheater is a commonly-used heat exchanging device at gas terminals of boilers in power plants, and the performance thereof directly influences the boiler heat efficiency. The conventional rotary air preheater normally uses metal as the heat exchanging medium, and only heat in the flue gas or smokes under 5001 may be recycled. By preheating combustion air, the flue gas heat may be carried back to a furnace hearth, and the combustion conditions may be improved accordingly so that the boiler efficiency thereof may be enhanced. When the flue gas may need to be denitrated, a SCR denitration method may be adopted for the denitration process in a conventional art. With the conventional SCR denitration method, a denitration device may need to be added at the end of the boiler. The denitration device may be provided before or behind the dust removing device. However, the conventional denitration method may have the following defects: 1. The denitration device may occupy relatively large space for available boilers, which are space deficient at the end portion; 2. If the denitration device may be arranged before the dust removing device, the flue gas may contains too much dust, which may be detrimental to catalysts, even, under * certain conditions, blockage etc; 3. If the denitration device may be arranged behind the dust removing device, the performance of the catalysts may be deteriorated since the flue gas temperature may be lowered, thus the denitrating efficiency may be reduced. SUMMARY Accordingly, the present invention in a first aspect provides a pulverized solid fuel boiler installed with a rotary-type regenerative heater comprising: a furnace hearth; a rotary-type regenerative heater comprising: a main heat exchanging body; a driving device for driving the main heat exchanging body to rotate about a central axis thereof; a separating member arranged in the main heat exchanging body along the central axis to separate the main heat exchanging body into at least a pair of receiving portions, each pair of the receiving portions being arranged diametrically in opposite, with respect to the central axis. a heat carrier received in the receiving portions respectively made of non-metal solid material, the heat carrier being provided with a denitrating catalyst layer; a flue gas passage, with an inlet thereof being communicated with a top part of the furnace hearth and an outlet thereof being communicated with the rotary-type regenerative heater so that a flue gas in the furnace hearth is introduced into one receiving portion of the paired receiving portions; and an air passage for introducing the air into the other receiving portion of the paired receiving portions so that the carrier received therein may exchange heat with the air. According to an embodiment of the present invention, when the heat carrier made of non-metal solid material is rotated, the flue gas with high temperature may heat up the heat carrier so that the temperature of the heat carrier arises quickly, and the denitrating catalyst layer in the heat carrier denitrates the flue gas with high temperature, thus NOx emission is reduced for the pulverized solid fuel boiler. In addition, the pulverized solid fuel boiler according to embodiments of the present invention may further have the following additional features: According to an embodiment of the present invention) the pulverized solid fuel may be coal dust, and the coal dust may be formed from at least one of anthracite or meagre coal. According to an embodiment of the present invention, a platen superheater, a wrapped wall superheater, and a superheater may be arranged in turn from the inlet of the flue gas passage toward the outlet of the flue gas passage. Thus, by arranging the superheaters, the recycling thermal efficiency of the steam power device may be effectively increased.

According to an embodiment of the present invention, a coal economizer may be provided in the flue gas passage near the outlet of the flue gas passage. Thus, by arranging the coal economizer, the heat may be effectively absorbed to lower the discharging temperature of the gas and save energy accordingly. 5 According to an embodiment of the present invention, the flue gas speed is adjustable when entering from the flue gas passage into the rotary-type regenerative heater. Thus, the temperature of the air to be preheated may be effectively increased. According to an embodiment of the present invention, the heat carrier is made of SiC or porcelain having a small ball shaped, scaly shaped, or porous structure. Thus, the D rotary-type regenerative heater may be high-temperature resistant, corrosion resistant and abrasion resistant. According to an embodiment of the present invention, the flue gas has a temperature of 50-80C after heat exchange via the rotary-type regenerative heater. According to an embodiment of the present invention, the air is oxygen-enriched, and 5 the air is heated up to 300-650' C after heat exchange via the rotary-type regenerative heater. Thus, the rising temperature of the air is high. According to an embodiment of the present invention, the rotary-type regenerative heater may further comprise a condensing liquid removing device provided under the main heat exchanging body, to remove the condensated liquid generated during D heat-exchange. Still further, the heat carrier may comprise a heat carrier upper layer provided with the denitrating catalyst layer and a heat carrier lower layer fixed with the heat carrier upper layer. Because the upper layer has a higher temperature, the denitrating efficiency is enhanced accordingly. 5 According to an embodiment of the present invention, the heat carrier is added with NOx catalyst. According to an embodiment of the present invention, the pulverized solid fuel has a diameter of 50-500um. Additional aspects and advantages of embodiments of present invention will be given D in part in the following descriptions, become apparent in part from the following descriptions, or be learned from the practice of the embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects and advantages of embodiments of the present invention will become apparent and more readily appreciated from the following descriptions made 5 with reference to the drawings, in which: Fig. 1 is a schematic view of a pulverized solid fuel boiler according to an embodiment of the present invention; Fig. 2 is a top view of a rotary-type regenerative heater in a pulverized solid fuel boiler according to an embodiment of the present invention. D DETAILED DESCRIPTION Reference will be made in detail to embodiments of the present invention. The embodiments described herein with reference to drawings are explanatory, illustrative, and used to generally understand the present invention. The embodiments shall not be 5 constructed to limit the present invention. The same or similar elements and the elements having same or similar functions are denoted by like reference numerals throughout the descriptions. In the specification, unless specified or limited otherwise, relative terms such as "central", "longitudinal", "up", "below", "front", "rear", "left", "right", "vertical", "horizontal", D "top", "bottom", "inner", "outer", "axial", and "radial" should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the present invention be constructed or operated in a particular orientation. In addition, terms such as "first" and "second" are used herein for purposes of description and are not intended to 5 indicate or imply relative importance or significance or to imply the number of indicated technical features. Thus, the feature defined with "first" and "second" may comprise one or more of this feature. In the description of the present invention, "a plurality of" means two or more than two, unless specified otherwise. In the description of the present invention, it should be understood that, unless D specified or limited otherwise, the terms "mounted," "connected," and "coupled" and variations thereof are used broadly and encompass such as mechanical or electrical mountings, connections and couplings, also can be inner mountings, connections and couplings of two components, and further can be direct and indirect mountings, connections, and couplings, which can be understood by those skilled in the art according to the detail embodiment of the present invention. 5 In the following, a pulverized solid fuel boiler system 100 is described according to an embodiment of the present invention. As shown in Fig. 1, the pulverized solid fuel boiler 1 according to an embodiment of the present invention may comprise a rotary-type regenerative heater 2, a flue gas passage 3 and an air passage 4. In the following, coal dust may be exemplarily used as D the pulverized solid fuel in the boiler for illustration purpose. However, the present invention is not limited hereto. Any powdered solid fuel may be used instead in the boiler for implementing the present conception, such as burned organic material. Alternatively, the diameter of the fuel may be of 50-500um. Thus, the coal dust mentioned hereinafter is used for exemplary and illustrative purpose, which is not meant for any limitation of the 5 scope of the present invention. The rotary-type regenerative heater 2 may perform heat exchanging between the flue gas with high temperature and the air to be preheated, so that the air to be preheated may be increased to a certain level. The rotary-type regenerative heater 2 may comprise a main heat exchanging body 21, a separating member 22 and a heat carrier 23, as D shown in Figs. 1 and 2. A driving device may be used to drive the main heat exchanging body 21 to rotate about a central axis 24 of the main heat exchanging body 21. The separating member 22 may be arranged in the main heat exchanging body 21 along the central axis 24 to separate the main heat exchanging body 21 into at least a pair of receiving portions 25, each pair of the receiving portions 25 being arranged diametrically 5 in opposite with respect to the central axis 24. The heat carrier 23 is received or contained in the receiving portions 25. And the heat carrier 23 may be made of non-metal solid material. According to an embodiment of the present invention, the heat carrier 23 may be added with NOx catalyst so that the NOx may be decreased, and because the heat carrier is loaded with NOx catalyst, a separate arranged NOx removing device may D be omitted at the flue gas outlet, so that the efficiency of the whole system may be increased whereas the cost may be reduced accordingly.

According to an embodiment of the present invention, the main heat exchanging body 21 may be formed into a hollowed cylindrical body, and the separating member 22 may be substantially of a plate shape. The separating member 22 may extend along the central axis of the main heat exchanging body 21 to separate the main heat exchanging 5 body 21 into a pair of receiving portions, and the heat carrier may be loaded in the two receiving portions which may be made of a non-metal solid material. And the heat carrier may be provided with a denitrating catalyst layer. The flue gas and the air to be preheated may be supplied into the two receiving portions. And the main heat exchanging body 21 may be driven to rotate by the driving device (not shown). The flue gas may exchange D heat with the heat carrier in the receiving portion to absorb the heat in the flue gas while the flue gas is denitrated so that NOx emission is reduced for the pulverized solid fuel boiler. The air to be preheated may exchange heat with the heat carrier in the other receiving portion so that the temperature of the air to be preheated is increased accordingly. 5 Of course, the present invention is not limited hereto. According to embodiments of the present invention, the separating member 22 may divide the main heat exchanging body 21 into two pairs, three pairs or more. In the prior heat exchanging system, the exit temperature of the flue gas after passing through the gas heat-exchanger may not be lowered to 130C or less, because D this may lead to sulphuric acid to be separated out, so that the gas heat-exchanger made of metal may be corroded. However, in the rotary-type regenerative heater 2 of the present invention, especially for the flue gas with high temperature containing sulfur, the heat carrier is made of a nonmetal solid material such as SiC or porcelain etc., the dew point of sulfur at 130C causing corrosion may not need to be considered, so that the exit 5 temperature of the flue gas with high temperature may be decreased to that less than the dew point of the sulfur, thus maximal heat exchanging may be performed. According to an embodiment of the present invention, the exit temperature of the flue gas with high temperature out of the gas heat-exchanger may be lower than 130C. Further, the exit temperature of the flue gas with high temperature out of the gas heat-exchanger may be D lower than 70C, which is almost impossible for conventional heat-exchanger. In addition, when the exit temperature is lower to less than the dew point, the water steam may be separated out into liquid water, so that latent heat may be released, and the heat absorbed 3 times when transiting from the liquid water having a temperature of 100'C to the gas water having a temperature of 100 C than that of the liquid water from 0 C to 100 'C. Because the heat carrier is made of non-metal solid material, the heat carrier in the 5 receiving portion may be cleansed for further use when the sulfur is deposited to a certain degree, so that component substitution cost may be decreased. In the flue gas heat exchange process of a coal combustion boiler, the whole boiler efficiency may be increased by 0.5% for each 10'C temperature decrease at the flue gas exit, and the released latent heat increases the efficiency of the boiler by approximately 1.5%. D According to the computation method commonly used in the art, by using the rotary-type regenerative heater, the cold air is heated to hot air to facilitate combustion, and the flue gas temperature may be decreased to 50-80'C, the residual heat of the fuel may be effectively utilized, and the boiler efficiency may be increased by 3% or more. In addition, the useable coal type for the pulverized solid fuel boiler may be enlarged, i.e., the coal 5 quality may be lowered to further reduce manufacturing cost. According to an embodiment of the present invention, the pulverized solid fuel boiler 1 may be defined with a furnace hearth 11. An inlet of the flue gas passage 3 may be communicated with a top part of the furnace hearth 11, and an outlet of the flue gas passage 3 may be communicated with the rotary-type regenerative heater 2 so that the D flue gas in the furnace hearth 11 is communicated into one receiving portion of the paired receiving portions to perform heat-exchange with the heat carrier contained in the corresponding receiving portions. The air passage 4 may introduce air into the other receiving portion of the paired receiving portions so that the heat carrier received therein may perform heat-exchange with the air accordingly. As shown in Fig. 1, the air after heat 5 exchanging is supplied into the furnace hearth 11 in a direction opposite to that of the flue gas. And the flue gas may flow out after performing heat-exchange in the rotary-type regenerative heater 2. In the following, for exemplary illustration purpose, the main heat exchanging body 21 is rotated in an anticlockwise direction, and the flue gas is supplied into the main heat D exchanging body 21 at the right side of the central axis, and the air to be preheated is supplied into the main heat exchanging body 21 from the left side of the central axis.

As shown in Fig. 1, the pulverized solid fuel boiler 1 is defined with the furnace hearth 11 to receive coal powder or coal dust, an end of the flue gas passage 3 is communicated with the furnace hearth 11, and the other end of the flue gas passage 3 is communicated with the rotary-type regenerative heater 2 to supply the flue gas generated 5 in the furnace hearth 11 into a first receiving portion 211 of the rotary-type regenerative heater 2, i.e. the right side of the rotary-type regenerative heater 2 as shown in Fig. 1. A second receiving portion 212 of the rotary-type regenerative heater 2, i.e. the left side of the rotary-type regenerative heater 2 as shown in Fig. 1, is supplied with the air to be preheated. When the main heat exchanging body 21 is not rotated, the flue gas exchange D heat with the heat carrier received in the first receiving portion 211 to increase the temperature of the heat carrier. After the heat carrier absorbs heat, the main heat exchanging body 21 is anticlockwisely rotated, the first receiving portion 211 is rotated to the left side of the central axis, and the second receiving portion 212 is rotated to the right side of the central axis. The heat carrier in the first receiving portion 211 rotated to the left 5 side performs heat-exchange with the air to be preheated, so that the air temperature is increased, while the flue gas performs heat-exchange with the heat carrier, the second receiving portion 212 rotates to the right side. The main heat exchanging body 21 is further rotated in the anticlockwise direction, and the first receiving portion 211 is rotated back to the right side of the central axis, and D the second receiving portion 212 is rotated back to left side of the central axis, the heat carrier in the second receiving portion 212 rotated back to the left side performs heat-exchange with the air to be preheated, and the flue gas performs heat-exchange with the heat carrier in the first receiving portion 211 rotated back to the right side, and the process is repeated to complete the heating of the air to be preheated. 5 According to an embodiment of the present invention, after the air to be preheated is heated up to a certain temperature, it may be supplied into the furnace hearth 11 from the bottom part of the pulverized solid fuel boiler 1, so that oxidizing combustion with high temperature may be performed with the coal powder in the furnace hearth 11. According to an embodiment of the present invention, the coal powder is made of at D least one of anthracite or meagre coal. The flue gas after performing heat exchange with the air to be preheated may be discharged via a discharging passage 101. According to the pulverized solid fuel boiler 1 of the present invention, the temperature of the flue gas with high temperature may be decreased to a large extent via the rotary-type regenerative heater 2, and the temperature of the heat carrier may be 5 increased more than that of the conventional art, and the denitrating efficiency may be improved accordingly. Thus, the flue gas may be denitrated to reduce NOx emission for the pulverized solid fuel boiler. Alternatively, a platen superheater 6, a wrapped wall superheater 7, and a superheater may be arranged in turn from the inlet of the flue gas passage 3 toward the D outlet of the flue gas passage 3. As shown in Fig. 1, the platen superheater 6, the wrapped wall superheater 7 and an additional superheater 8 may be provided neighboring the inlet of the flue gas passage 3, and separated from each other in the left-to-right direction, and the superheater may be provided near the outlet of the flue gas passage 3. Thus, by the superheaters, the whole steam powering device may have an 5 increased recycling thermal efficiency. Further, a coal economizer 9 may be provided in the flue gas passage 3 near the outlet of the flue gas passage 3. As shown in Fig.1, the coal economizer 9 may be provided under the superheater 8 with a distance therebetween in a vertical direction. Thus, by the coal economizer 9, the heat of the flue gas may be effectively absorbed, and D the flue gas temperature may be lowered to save fuel accordingly. According to an embodiment of the present invention, the flue gas speed is adjustable when entering from the flue gas passage 3 into the rotary-type regenerative heater 2. Thus, the temperature of the air to be preheated may be effectively increased. Alternatively, the heat carrier may be made of SiC or porcelain having a small ball 5 shaped, scaly shaped, or porous structure. Thus, the rotary-type regenerative heater 2 may be high-temperature resistant, corrosion resistant and abrasion resistant. According to an embodiment of the present invention, the rotary-type regenerative heater may further comprise a condensing liquid removing device 10 provided under the main heat exchanging body 21 to remove the condensated liquid generated during heat D exchanging, such as condensated water containing acid etc. According to an embodiment of the present invention, the flue gas has a temperature of 50-80'C after heat exchanging via the rotary-type regenerative heater 2. At this time, the steam in the flue gas may be separated out to react with the sulphur trioxide forming condensated water having acid, and 30% sulfur in the gas may be removed by the condensing liquid removing device, so that the sulfur may be pre-denitrated accordingly, 5 thus decreasing the subsequent denitration cost of the flue gas tremendously. In addition, a part of the latent heat in the flue gas may be recycled to increase the thermal efficiency of the boiler accordingly. According to an embodiment of the present invention, the air is oxygen-enriched, and the air may be heated up to 300-650 C after heat exchanging via the rotary-type D regenerative heater 2. Thus, there is a relatively high temperature increase for the air to be preheated. Further, to facilitate manufacture, heat carrier may be provided with a heat carrier upper layer and a heat carrier lower layer (not shown). The heat carrier upper layer may be provided with the denitrating catalyst layer. And the heat carrier lower layer may be 5 fixed with the heat carrier upper layer via, for example, welding, bolting or threading etc. And the dimension of the heat carrier upper layer may be determined by the specific requirement of the in-site boiler model. Reference throughout this specification to "an embodiment," "some embodiments," "one embodiment", "another example," "an example," "a specific example," or "some D examples," means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. Thus, the appearances of the phrases such as "in some embodiments," "in one embodiment", "in an embodiment", "in another example," "in an example," "in a specific example," or "in some examples," in various places throughout 5 this specification are not necessarily referring to the same embodiment or example of the present invention. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples. Although explanatory embodiments have been shown and described, it would be D appreciated by those skilled in the art that the above embodiments cannot be construed to limit the present invention, and changes, alternatives, and modifications can be made in the embodiments without departing from spirit, principles and scope of the present invention. The term 'comprise' and variants of the term such as 'comprises' or 'comprising' are used herein to denote the inclusion of a stated integer or stated integers but not to exclude any other integer or any other integers, unless in the context or usage an exclusive interpretation of the term is required. Any reference to publications cited in this specification is not an admission that the disclosures constitute common general knowledge in Australia.

Claims

1. A pulverized solid fuel boiler installed with a rotary-type regenerative heater, comprising: a furnace hearth; 5 a rotary-type regenerative heater, comprising: a main heat exchanging body; a driving device for driving the main heat exchanging body to rotate about a central axis thereof; a separating member arranged in the main heat exchanging body along the D central axis, to separate the main heat exchanging body into at least a pair of receiving portions, each pair of the receiving portions being arranged diametrically in opposite with respect to the central axis; a heat carrier received in the receiving portions respectively made of a non-metal solid material, the heat carrier being provided with a denitrating catalyst layer; 5 a flue gas passage, with an inlet thereof being communicated with a top part of the furnace hearth and an outlet thereof being communicated with the rotary-type regenerative heater, so that a flue gas in the furnace hearth is introduced into at least one receiving portion of the paired receiving portions and exchanges heat with the heat carrier; D an air passage for introducing the air into the other receiving portion of the paired receiving portions, so that the heat carrier received therein exchanges heat with the air.

2. The pulverized solid fuel boiler according to claim 1, wherein the pulverized solid fuel is coal powder, and the coal powder is made of at least one of anthracite or meagre coal. 5

3. The pulverized solid fuel boiler according to claim 1, further comprising a platen superheater, a wrapped wall superheater, and a superheater arranged in turn from the inlet of the flue gas passage toward the outlet of the flue gas passage.

4. The pulverized solid fuel boiler according to claim 3, wherein a coal economizer is provided in the flue gas passage near the outlet thereof. D

5. The pulverized solid fuel boiler according to claim 1, wherein the flue gas speed is adjustable when entering from the flue gas passage into the rotary-type regenerative heater.

6. The pulverized solid fuel boiler according to claim 1, wherein the heat carrier is made of SiC or porcelain having a small ball shaped, scaly shaped, or porous structure.

7. The pulverized solid fuel boiler according to claim 1, wherein the flue gas has a temperature of 50-80'C after heat exchange via the rotary-type regenerative heater.

8. The pulverized solid fuel boiler according to claim 1, wherein the air is 5 oxygen-enriched, and the air is heated up to 300-650'C after heat exchange via the rotary-type regenerative heater.

9. The pulverized solid fuel boiler according to claim 1, wherein the rotary-type regenerative heater further comprises: a condensing liquid removing device provided under the main heat exchanging body, D to remove the condensated liquid generated during heat exchange.

10. The pulverized solid fuel boiler according to claim 1, wherein the heat carrier comprises: a heat carrier upper layer provided with the denitrating catalyst layer; and a heat carrier lower layer fixed with the heat carrier upper layer. 5

11. The pulverized solid fuel boiler according to claim 1, wherein the heat carrier is added with NOx catalyst.

12. The pulverized solid fuel boiler according to claim 1, wherein the pulverized solid fuel has a diameter of 50-500um.