WO2013045548A1

WO2013045548A1 - Apparatus and method for preparing a ballast bed

Info

Publication number: WO2013045548A1
Application number: PCT/EP2012/069080
Authority: WO
Inventors: Chenxi Zhang; Gang Sun
Original assignee: Bayer Intellectual Property Gmbh
Priority date: 2011-09-29
Filing date: 2012-09-27
Publication date: 2013-04-04
Also published as: CN103031786B; CN103031786A

Abstract

The present invention relates to an apparatus for preparing thermosetting polymer ballast bed, said ballast bed comprising ballasts and thermosetting polymers formed among the ballasts by curing a thermosetting polymer reaction system. The apparatus comprises a heating unit and a fixing unit, and the heating unit comprises an electrical heating unit for providing heat to the ballast bed to facilitate the curing of the thermosetting polymer reaction system after being introducing it to the ballasts, and the fixing unit is used to keep the heating unit at a predetermined distance from the ballast bed surface. The apparatus of the present invention can promote the curing of thermosetting polymer reaction system, and preheat and/or dry the ballast bed.

Description

APPARATUS AND METHOD FOR PREPARING A BALLAST BED

Field of the Invention

[0001] The present invention relates to an apparatus, a use thereof and a method for preparing ballast bed, in particular a polyurethane foam ballast bed.

Background of the Invention

[0002] Ballast rail track beds are usually referred to as ballast beds, which are mainly composed of ballasts. They are used to distribute the heavy loading from railway vehicles, transferred from rails and sleepers, evenly across the surface of roadbed to reduce the deformation of roadbed thereby ensuring traffic safety.

[0003] Over time, the collision, dislocation, and crushing of ballasts under heavy loading on the ballast bed causes deformation and functional deterioration of the ballast bed. Usually, injecting polymer curing system into the ballast bed can form a stable thermosetting polymer ballast bed. For example, US2007172590A discloses a method using a polyurethane reaction system for stabilizing ballast bed, which is composed of ballasts and polyurethane foam. The polyurethane foam is produced from the reaction mixture of isocyanate and chemical compounds, which can react with isocyanate. KR2006076652 discloses a single-component moisture-cured ballast adhesive to prevent the splash of ballasts. The adhesive is the mixture of solvent and curing accelerator. CN1399035 discloses a curing method and use for railway roadbed ballasts. This method uses styrene-bu tadi en e latex, butylamine rubber, aniline rubber, liquid rubber and other similar polymers for curing of the ballasts on railway roadbed, so that the ballasts can be cured and bonded, thereby achieving the purpose of fixing the track bed. US3788883 discloses a method of using styrene and butadiene copolymer elastomer adhesive to fix ballasts.

[0004] A thermosetting polymer ballast bed is obtained through applying a thermosetting polymer reaction system into a ballast bed, wherein the thermosetting polymer reaction system is cured within the spaces among the ballasts to form thermosetting polymers. Generally, curing of thermosetting polymer reaction system takes long time to finish. In addition, before complete curing of a thermosetting polymer reaction system, opening to traffic can destroy the bonding between the thermosetting polymers and ballasts, leading to shortened life span of the thermosetting polymer ballast bed.

[0005] Furthermore, during the construction or maintenance of railway in cold regions, in most cases, the track bed needs to be preheated to a temperature suitable for the application of thermosetting polymer reaction systems, followed by injecting thermosetting polymer reaction systems; during the construction or maintenance of railway in humid regions, in most cases, the ballast bed needs to be dried at first to remove water, then followed by injecting thermosetting polymer reaction systems. Existing preheating and drying equipment for ballast beds are usually large-scale heating equipment riding on rails. Therefore, when ballast beds need to be preheated or dried, railway is occupied so that other vehicles cannot pass by.

[0006] Consequently, there is a need to provide an apparatus for promoting curing of thermosetting polymer reaction systems applied on ballast beds.

Summary of the Invention

[0007| One object of the present invention is to provide an apparatus for preparing a thermosetting polymer ballast bed, the ballast bed comprises ballasts and thermosetting polymers formed among the ballasts by curing a thermosetting polymer reaction system, wherein the apparatus comprises a heating unit and a fixing unit, and the heating unit comprises an electrical heating unit for providing heat to the ballast bed to promote curing of the thermosetting polymer reaction system after introducing it to the ballasts, and the fixing unit is used to keep the heating unit at a predetermined distance from the surface of the ballast bed.

[0008] In one embodiment of the present invention, the predetermined distance is 5 cm to 25 cm.

[0009] In another embodiment of the present invention, the apparatus further comprises a cover, in which the heating unit is disposed, for reflecting and outputting the heat produced by the heating unit. Preferably, the cover is open or has a grid structure along the heat reflecting and outputting direction.

[0010] In yet another embodiment of the present invention, the cover has a form of cuboids with a length of 50-300 cm, a width of 20-60 cm, and a height of 1-30 cm. Preferably, a heat preservation layer is disposed on at least one of the front facet, top facet and side facet. More preferably, the heat preservation layer is disposed on the internal surface, the external surface or intermediate sections of the cover.

[0011] In still another embodiment of the present invention, the apparatus further comprises one or more air-blowing device, which is disposed on top of the cover to enhance the output of the heat produced by the heating unit.

[0012] In still another embodiment of the present invention, the thermosetting polymers are one or more selected from the group consisting of polyurethane, epoxy resin, acrylic resin and any combination thereof.

[0013] Another object of the present invention is to provide a method for preparing a thermosetting polymer ballast bed, comprising the steps of: (a) providing a ballast bed;

(b) applying a thermosetting polymer reaction system to the ballast bed, wherein the thermosetting polymers are formed among the ballasts by curing of a thermosetting polymers reaction system; and

(c) heating the ballast bed by the above mentioned apparatus to cure the thermosetting polymer reaction system to form thermosetting polymers, thus obtaining the thermosetting polymer ballast bed.

[0014] In one embodiment of the present invention, the process further comprises a step of preheating or drying the ballasts of the ballast bed before step (b) by the apparatus mentioned above.

[00151 In another embodiment of the present invention, the thermosetting polymers are one or more selected from the group coasisting of polyurethane, epoxy resin, acrylic resin and any combination thereof.

[0016| Yet another object of the present invention is to provide a use of the apparatus mentioned above in drying and/or preheating ballast beds.

[0017J Still another object of the present invention is to provide a use of the apparatus mentioned above in preparing thermosetting polymer ballast beds.

Description of Figures

[0018] Figure 1 shows a schematic diagram describing the apparatus 100 according to one embodiment of the invention;

[0019] Figure 2 shows schematic diagram of the apparatus described in Figure 1 along longitudinal axis;

[0020] Figure 3 shows a schematic diagram describing the apparatus 300 according to one embodiment of the invention;

[0021 ] Figure 4 shows a schematic diagram describing the method of preparing polyurethane cured ballast bed according to one embodiment of the invention; and

[0022] Figure 5 shows a diagram describing the method of preparing polyurethane cured ballast bed according to one embodiment of the invention.

Detailed Description of the Invention

[0023] The apparatus for preparing thermosetting polymer ballast beds disclosed in the present invention can be used not only to preheat or dry ballast beds, but also to facilitate curing of the thermosetting polymer reaction system to form the thermosetting polymers among ballasts after being introduced to the ballast bed, thus preparing the thermosetting polymer ballast bed.

[0024] As used herein, the term "ballast bed" refers to the ballast bed which has not been applied with thermosetting polymer reaction system.

[0025] As used herein, the term "thermosetting polymer reaction system" refers to a system comprising one or more component which may be applied to ballasts after mixing. The physical and/or chemical reactions of the component may form the thermosetting polymers encapsulating or binding ballasts, and the reactions may be promoted by heat. Examples of thermosetting polymer reaction system of the present invention include, but not limited to the polyurethane system disclosed in US 2007172590A, one component moist-curable ballast sealant system comprising solvent and cure accelerator disclosed in KR2006076652, liquid rubber thermosetting polymer reaction system such as styrene-butadiene latex, butylamine rubber, and aniline rubber disclosed in C 1399035, and elastomer adhesive reaction system comprising the copolymer of styrene and butadiene disclosed in US3788883, the disclosure of all of above is incorporated herein by reference in its entirely.

[0026] As used herein, the term "thermosetting polymer" refers to the product obtained by completely curing thermosetting polymer reaction system. The example of the thermosetting polymers include, but not limited to, polyurethane foam, polyurethane elastomer, epoxy resin, acrylic resin, styrene-butadiene rubber, chloroprene rubber, aniline rubber, nitrile rubber and the like. Preferably, the thermosetting polymers which are useful in the present invention are polyurethane, epoxy resin, acrylic resin or combination thereof.

[0027] As used herein, the term "thermosetting polymer ballast bed" refers to the ballast bed obtained by applying the thermosetting reaction system to ballast bed and subsequent curing.

[0028] As used herein, the term "cure" or "curing" refers to the process that the component of thermosetting polymer reaction system, after being applied to ballasts, react to form thermosetting polymers. It's well known in the art that the curing process can be promoted by providing appropriate amount of heat.

[0029] The present invention will hereinafter be described in conjunction with the appended drawings.

[0030] Figure 1 shows a schematic diagram describing the apparatus 100 according to one embodiment of the invention. As shown in Figure 1, the apparatus comprises cover 110, fixing unit 1 0 and a heating unit (not shown).

[0031] Cover 110 shown in Figure 1 is an optional unit, which is used to reflect and output heat produced by the heating unit. The heating unit can be fixed on rail, sleeper or ballast bed directly through fixing unit 120, or disposed in the cover 110 which is disposed on ballast bed, or on a rail lying on ballast bed, or between two adjacent rails.

[0032] In one preferred embodiment of the present invention, the cover 110 is open or has a grid structure in the heat reflecting and outputting direction, which will help the heat transfer to the ballast bed. Preferably, the cover 110 has a grid structure in the heat reflecting and outputting direction, so as to prevent the damage of heating unit in the cover 110 by ballasts.

[0033] The cover 110 can be of any shape, not limited to the cuboid shape as shown in Figure 1 , for example it can be oval shaped, cone-shaped or irregular shaped.

[0034| The cover 110 may be rigid or flexible, for example, it may be flexible laminated material which can be spread on area to be heated for heating.

[0035| The cover 110 may be made of any materials, including but not limited to metal and non-metal materials, and preferably made of aluminum, aluminum alloy, stainless steel and the like. A handle may be installed on the cover 110 for the convenience of moving.

[0036] Preferably, the cover 110 has a cuboid shape as shown in Figure 1 with a top facet 1 16, head facet 112 and 112', side facet 1 14 and 114', and bottom facet 118, wherein the bottom facet 118 is open or has a grid structure. In the present invention, the cuboid shape includes cubic shape.

[0037] Preferably, the cuboid cover 1 10 has a length of 50-300 cm, a width of 20-60 cm and a height of 1-30 cm. Cover 1 10 can be conveniently disposed in a crib with the bottom facet 1 18 maintained at a certain distance from the ballast bed surface, thus avoid the damage of the heating unit by ballasts. In addition, the two side faces 114 and 114' of the cuboid cover 110 are close to sleepers when disposed in the crib, thus avoid heat loss. More preferably, the cuboid cover has a length of 100 -130 cm, so that the apparatus may be easily disposed in crib from bottom of sleepers.

[0038] The fixing unit 120 is used to fix the heating unit to keep the heating unit at a predetermined distance from the ballast bed surface. The predetermined distance may be from 5 cm to 25 cm, that is to say that the heating unit may be disposed in the crib or out of the crib. Preferably, the predetermined distance is from 5 cm to 15 cm, so the apparatus can be disposed in the crib, thus not hindering railway vehicle's running on rails. When the apparatus has a cover 1 10, the fixing unit 120 can be disposed on the cover 1 10 so as to fix the apparatus 100 in the crib.

[0039] The fixing unit 120 may be in the form of a bracket or a clamp and the like. For example, the fixing unit 120 may be several brackets disposed on the bottom of the cover 1 10. The brackets may be disposed on the cover U O or be separated for supporting the cover 1 10.

[0040] Preferably, the fixing unit 120 is a clamp mounted on the cover 1 10, thus the cover 1 10 may be fixed in the crib by clamping on rails or sleepers. For example, as shown in Figure 1 , the fixing unit comprises element 122 and 124. The element 122 is a fixed one which may be fixed on the top facet of the cover 110, and the other end is hooked to the rail's underside. The element 124 is a movable one which can fix the apparatus 100 on one side of the rail's underside by clamping. The example of the element 124 includes, but not limited to, horizontal type clamp, push-pull type clamp, vertical type clamp, bolt and the like. One or more groups of the element 124 may be disposed for clamping two sides of the rail's underside. [0041] The apparatus of the present invention further comprises a heating unit, which is fixed by the fixing unit 120 at a predetermined distance from the ballast bed surface. The heating unit is used to preheat or dry ballast bed or promote the curing of the thermosetting polymer reaction system. As mentioned, the predetermined distance may be 5-25 cm, preferably 5-15 cm. As shown in Figure 2, the heating unit comprises an electrical heating unit 142 which is used to provide heat to ballast bed to promote the curing of the thermosetting polymer reaction system.

[00421 Preferably, the heating unit comprises power, a heating element, a heating circuit with a switch which may further comprises temperature controlling devices and the like. As shown in Figure 2, the electrical heating element 142 of the heating unit is disposed in the cover, while the power and switch may be disposed on the cover with the electrical heating element or provided separately.

[0043| Preferably, the electric heating element 142 includes, but not limited to, an electrical heating wire, an electric heating strip, an electric heating pipe, an electric heating plate and the like. Said electric heating wire includes nickel-chromium wires, iron-chromium-aluminum alloy wires, electric heating flat strips, copper-nickel alloy wires and the like. Said electric heating strip includes nickel-chromium alloy flat strips, silicone rubber heating strips, glass fiber heating strips, ceramic heating strips and the like. Said electric heating pipe includes infrared radiation heating tubes, single head electric heating tubes, position-limited single end electric heating tubes, temperature-measurable single end electric heating tubes, water-proof electric heating tubes, double head electric heating tubes, U-shaped electric heating tubes, W-shaped electric heating tubes, opal quartz electric heating tubes, reflector-equipped quartz electric heating tubes, quartz electric heating tubes, infrared straight electric heating tubes, ceramic electric heating tubes and the like. Said electric heating plate includes quartz plate heaters, far-infrared quartz heating plates, ceramic electric heating plates, far-infrared ceramic heating plates and the like.

[0044] In one embodiment of the present invention, a flexible curtain may be disposed on two head facet 1 12 and 1 12'. Together with the bottom facet of the cover of the present invention and the surface of the ballast bed, an essentially closed space is formed, thus reducing the heat loss. Preferably, the flexible curtain may be made from silicon rubber, polymer foam and combination thereof.

[0045] in one embodiment of the present invention, insulation layers may be disposed on the internal surface, the external surface or intermediate sections of one or more facets of the head, top and side facet of the cover 110. The insulation layer can be made of insulation materials, preferably light weight porous iasulation materials and reflective insulation materials. The insulation material which could be used in the present invention includes, but not limited to, polyurethane rigid foams, mineral fibers (such as asbestos), expanded perlites and porous concrete, foam glasses, insulation blankets, aluminum foils and the like. [0046] In another embodiment of the present invention, the apparatus further comprises one or more blowing devices. As shown in Figure 3, a blowing device 160 is disposed on the top facet of the cover to enhance the transfer of heat, produced by the heating unit, to the ballast bed. The blowing device can be two as shown in figure 3, or one or three or more.

[0047] The present invention further provides a method for preparing thermosetting polymer ballast beds. The process takes advantage of the apparatus illustrated above to dry or preheat ballast beds, or to promote the curing of the thermosetting polymer reaction system and the formation of the thermosetting polymers among ballasts, thus producing the thermosetting polymer ballast beds.

[0048] According to one embodiment of the present invention, the method comprises the steps:

(a) providing a ballast bed;

(b) applying a thermosetting polymer reaction system to the ballast bed; and

(c) heating the ballast bed by the apparatus illustrated above to cure the thermosetting polymer reaction system to form the thermosetting polymer, thus obtaining the thermosetting polymer ballast bed.

[0049] Figure 4 shows a schematic diagram describing the method for preparing thermosetting polymer ballast beds according to one embodiment of the present invention. As show in Figure 4, the ballast bed acquired may be a newly-built ballast bed or an existing one. The ballast bed may comprise ballast layer 410 which comprises ballasts 415 and thermosetting polymers 420. Sleepers 440, rail 460 and fasteners 430 are disposed on the ballast beds. A crib 450 is the space between two sleepers.

[0050] The thermosetting polymer reaction system may be applied into the acquired ballast bed by the process well-known in the art, for example injection, spraying and the like.

[0051] The apparatus of the present invention 470 may be fixed by the fixing unit 480 to keep the apparatus at a predetermined distance from the ballast bed surface. The predetermined distance may be 5-25 cm, preferably 5-15 cm; this way the apparatus can be disposed in the crib 450, thus the railway vehicle's operation will not be affected.

[0052] In one preferred embodiment of the present invention, the method of the present invention further comprises the step:

Preheating or drying the ballast bed using one or more of the above said apparatus prior to step (b). That is to say that the thermosetting polymer reaction system is applied into the ballast bed after the ballast bed is preheated or dried to remove moisture, thus facilitate the curing of the thermosetting polymer reaction system.

[0053] According to one embodiment of the present invention, two of the apparatus of the present invention can be hung in the crib side by side through the fixing unit. As shown in Figure 5, ballast track comprises ballast layer 510, sleeper 540 and rail 560. Two apparatus 570 are fixed on two rails 560 by their fixing unit 580, thus the efficiency of promoting the curing of the thermosetting polymer reaction system may be further improved. One group of two apparatus of the present invention can be disposed to heat the ballast bed in one crib formed between adjacent sleepers. A couple of such groups can be used to prepare the polyurethane ballast bed, and the number of such groups used may be decided according to the length of the ballast bed to be heated, for example 10 groups of the apparatus can be used to heat a ballast bed with a length of 6 meters, 30 groups for 18 meters, and 60 groups for 36 meters.

[0054| Another object of the present invention is to provide a thermosetting polymer ballast bed which is obtained by the above mentioned method.

[0055J For example, the polyurethane foam of the polyurethane ballast bed obtained by the method of the present invention has a density of 0.02-0.5 g/cm³ measured according to DIN EN ISO 845; a hardness of 5-60 Asker C, preferably 10-40 Asker C measured according to DIN 53505; and a breaking elongation of 120-400% measured according to EN ISO 527.

[0056] Still another object of the present invention is the use of the apparatus of the present invention in preheating and/or drying ballast bed to promote the curing of the thermosetting polymer reaction system.

Examples

[0057] The following examples are included to demonstrate preferred embodiments of the invention. It should be appreciated by those skilled in the art that the disclosed examples can be considered to constitute preferred modes for its practice. However, those skilled in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention.

[0058] The materials and devices used in the examples are listed as following:

Desmodur ΡΛ09: isocyanate prepolymer, NCO content 24.5%, viscosity at 25 ^°C 475 mPa*s, purchased from Bayer Material Science;

Desmodur 0309: isocyanate prepolymer, NCO content 9.9%, viscosity at 25 ^"C 2750 mPa^»s, purchased from Bayer Material Science;

BAYTEC 52BC003: sprayable polyether polyol, hydroxyl number 205, viscosity at 25 °C

1100 mPa^»s, purchased from Bayer Material Science;

Bayflex 12BX012: polyether polyol, hydroxyl number 102, viscosity at 25 °C 1050 mPa^«s, purchased from Bayer Material Science;

HK 1250: conventional high pressure injection machine, purchased from Hennecke;

H-XP3: conventional high pressure spraying machine, purchased from GRACO. Comparison example 1

[0059] The polyurethane reaction system comprising DESMODUR PA 09 and BAYFLEX 12BX012 was injected into the gaps among ballasts by the HK 1250 conventional high pressure injection machine. It took 6 hours for the polyurethane reaction system to cure at ambient temperature to obtain polyurethane thermosetting materials.

Example 1

[0060] The polyurethane reaction system comprising DESMODUR 0309 and BAYTEC 52BC003 was sprayed to the ballasts after mixing, and cured to form polyurethane foam polymer materials. The polyurethane thermosetting polymer materials were a ballast-adhesive polymer formed among ballasts. 30 groups of the apparatus of the present invention were disposed in the crib under the rails to promote the curing of the polyurethane reaction system to form the polyurethane thermosetting polymer materials. The apparatus bottom was set at a distance of 10 cm from the surface of the ballast bed. Two hours were needed to completely cure a ballast bed with a length of 18 meters.

[0061] The apparatus used in the present example is shown in Figure 1 and 2, which comprises a cuboid-shaped cover 110, a fixing unit 120 disposed on the cover 110, and a heating unit disposed on the inner side of the cover 1 10. The fixing unit 120 comprises a push-pull type clatnp and a fixing element 122. The heating unit comprises a power which is provided externally and an electric heating wire 142 which is disposed on the inner side of the cover 110.

Example 2

[0062] The polyurethane reaction system comprising DESMODU R PA 09 and BAYFLEX 12BX012 was injected into the gaps among ballasts by the HK 1250 conventional high pressure injection machine, and cured to form polyurethane thermosetting polymer materials. The polyurethane thermosetting polymer materials were polyurethane foams formed among ballasts. 40 groups of the apparatus of the present invention were disposed in the crib under the rails to promote the curing of the polyurethane reaction system to form the polyurethane thermosetting polymer materials. The bottom of the apparatus was set at a distance of 10 cm from the surface of the ballast bed. It took 2 hours for a ballast bed with a length of 24 meters to cure completely.

[0063] The apparatus used in the present example is shown in Figure 3, which comprises a cuboid-shaped cover 1 10, a fixing unit 120 disposed on the cover 1 10, and a heating unit disposed on the inner side of the cover 1 10. The fixing unit 120 comprises a push-pull type clamp and a fixing element 122. The heating unit comprises an electric supply which is provided externally and an electric heating wire 142 which is disposed on the inner side of the cover 110.

Example 3

[0064] The present example refers to the method of preparing polyurethane polymer ballast beds under low temperature (about 10-15^°C). First, 60 groups of the apparatus of example 2 were disposed in the crib to heat the track to a room temperature (about 25^°C).The bottom of the apparatus was set at a distance of 10 cm from the surface of the ballast bed. It took 1 hour for a ballast bed with a length of 36 meters to be heated to room temperature. The 60 groups of apparatus were removed quickly after preheating.

[0065] The polyurethane reaction system comprising DESMODU R PA 09 and BAYFLEX 12BX012 was injected into the gaps among ballasts by the HK 1250 conventional high pressure injection machine, and cured to form polyurethane thermosetting polymer materials. The polyurethane thermosetting polymer materials were polyurethane foams formed among ballasts. 60 groups of the apparatus of the present invention were disposed in the crib under the rails to promote the curing of the polyurethane reaction system to form the polyurethane thermosetting polymer materials. The bottom of the apparatus was set at a distance of 10 cm from the surface of the ballast bed. It took 2 hours for a ballast bed with a length of 36 meters to cure completely.

[0066] The present example refers to the method of preparing polyurethane ballast beds by applying polyurethane reaction system under the temperature lower than room temperature. Since the polyurethane reaction system needed at least 8 hours to cure completely under low temperature, about 10-15^°C, the ballast bed needed to be preheated to allow application of the polyurethane polymer reaction system. After preheating, it took only about 3 hours for the polyurethane reaction system to cure completely.

[0067] It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. An apparatus for preparing a thermosetting polymer ballast bed, the ballast bed comprising ballasts and thermosetting polymers formed among the ballasts by curing a thermosetting polymer reaction system, wherein the apparatus comprises a heating unit and a fixing unit, and the heating unit comprises an electrical heating unit for providing heat to the ballast bed to promote curing of the thermosetting polymer reaction system after being introducing it to the ballasts, and the fixing unit is used to keep the heating unit at a predetermined distance from the ballast bed surface.

2. The apparatus according to claim 1 , wherein the predetermined distance is 5 cm to 25 cm.

3. The apparatus according to claim 1 or 2, wherein the apparatus further comprises a cover, in which the heating unit is disposed, for reflecting and outputting the heat produced by the heating unit.

4. The apparatus according to claim 3, wherein the cover is open or has a grid structure along the heat reflecting and outputting direction.

5. The apparatus according to claim 4, wherein the cover has a form of cuboids with a length of 50-300 cm, a width of 20-60 cm, and a height of 1-30 cm.

6. The apparatus according to claim 5, wherein a heat preservation layer is disposed on at least one of the head facet, top facet and side facet.

7. The apparatus according to claim 6, wherein the heat preservation layer is disposed on the internal surface, external surface or intermediate sections of the cover.

8. The apparatus according to claim 4, wherein the apparatus further comprises one or more air-blowing device, which is disposed on top of the cover to enhance the output of the heat produced by the heating unit.

9. The apparatus according to any one of claims 1-8, wherein the thermosetting polymers are one or more selected from the group consisting of polyurethane, epoxy resin, acrylic resin and any combination thereof. 0. A method for preparing a thermosetting polymer ballast bed, comprising the steps of: (a) providing a ballast bed;

(b) applying a thermosetting polymer reaction system to the ballast bed; and

(c) heating the ballast bed by the apparatus according to any one of the claims 1-9 to cure the thermosetting polymer reaction system to form a thermosetting polymer, and obtaining the thermosetting polymer ballast bed.

11. The method according to claim 10, further comprising a step of preheating or drying ballasts of the ballast bed before step (b) by the apparatus according to any one of the claims 1 -9.

12. The method according to claim 10 or 11 , wherein the thermosetting polymers are one or more selected from the group consisting of polyurethane, epoxy resin, acrylic resin and any combination thereof.

13. Λ use of the apparatus according to any one of claims 1-9 in drying and/or preheating a ballast bed.