阅读说明：本技术 一种铅膏脱硫剂的循环再生工艺及其反应设备 (Cyclic regeneration process and reaction equipment for lead plaster desulfurizer ) 是由 李怀程 杨正群 于 2020-12-17 设计创作，主要内容包括：本发明涉及废旧铅酸蓄电池的回收领域,公开了一种铅膏脱硫剂的循环再生工艺,包括以下步骤：S1,将脱硫后的混合物进行过滤,得滤液；S2,向滤液中加入沉淀剂,使得沉淀剂与滤液进行反应,将硫酸根离子沉淀；S3,反应完成后静置、过滤,所得液体为脱硫剂的溶液。本发明能够降低脱硫成本。(The invention relates to the field of recovery of waste lead-acid storage batteries, and discloses a cyclic regeneration process of a lead plaster desulfurizer, which comprises the following steps: s1, filtering the desulfurized mixture to obtain filtrate; s2, adding a precipitating agent into the filtrate to enable the precipitating agent to react with the filtrate and precipitate sulfate ions; s3, standing and filtering after the reaction is finished, wherein the obtained liquid is the solution of the desulfurizer. The invention can reduce the desulfurization cost.)

1. A cyclic regeneration process of a lead plaster desulfurizer is characterized by comprising the following steps: the method comprises the following steps:

s1, filtering the desulfurized mixture to obtain filtrate;

s2, adding a precipitating agent into the filtrate to enable the precipitating agent to react with the filtrate and precipitate sulfate ions;

s3, standing and filtering after the reaction is finished, wherein the obtained liquid is the solution of the desulfurizer.

2. The recycling process of the lead plaster desulfurizer as claimed in claim 1, which is characterized in that: said precipitating agent comprises XCO₃In which XSO₄Is a precipitate, and the XSO₄Has a solubility product less than that of XCO₃The product of solubility of (c).

3. The recycling process of the lead plaster desulfurizer as claimed in claim 2, which is characterized in that: and X is Ba.

4. The recycling process of the lead plaster desulfurizer as claimed in claim 1, which is characterized in that: the precipitator is calcium oxide or calcium hydroxide.

5. The recycling process of the lead plaster desulfurizer as claimed in claim 1, which is characterized in that: the mixture was stirred in said S2.

6. A reaction apparatus for implementing a cyclic regeneration process of a lead plaster desulfurizer as defined in any one of claims 1 to 5, characterized in that: comprises the steps of (a) preparing a mixture of a plurality of raw materials,

the device comprises a reaction vessel (1), a liquid inlet pipe (2) communicated with the top of the reaction vessel (1) and a liquid outlet pipe (3) communicated with the bottom of the reaction vessel (1), wherein a first control valve (4) and a second control valve (5) are respectively arranged on the liquid inlet pipe (2) and the liquid outlet pipe (3);

the stirring rod (6) is vertically and rotatably arranged in the middle of the reaction vessel (1), a spiral lifting piece (7) is wound on the outer wall of the stirring rod (6), and a driving mechanism for driving the stirring rod (6) to rotate is arranged on the reaction vessel (1);

the extraction tube (8), the extraction tube (8) communicate in the top of reaction ware (1), be provided with third control valve (9) on extraction tube (8).

7. The reaction equipment in the cyclic regeneration process of the lead plaster desulfurizer according to claim 6, wherein the reaction equipment comprises: the lifting piece (7) and the minimum distance between the axes of the stirring rods (6) are gradually reduced along with the increase of the height, and a plurality of crushing holes (10) are formed in the lifting piece (7).

8. The reaction equipment in the cyclic regeneration process of the lead plaster desulfurizer according to claim 6, wherein the reaction equipment comprises: the reaction vessel is characterized by further comprising a circulating pipe (11), wherein two ends of the circulating pipe (11) are respectively communicated with the top and the bottom of the reaction vessel (1), and a circulating pump (12) is arranged on the circulating pipe (11).

9. The reaction equipment in the cyclic regeneration process of the lead plaster desulfurizer according to claim 8, wherein the reaction equipment comprises: the driving mechanism comprises a driving motor (13) arranged above the reaction vessel (1) and a driving tooth (14) connected with the driving motor (13), the stirring rod (6) comprises a hollow blanking part (6a) and a stirring part (6b) positioned right below the blanking part (6a), the lifting piece (7) is positioned on the stirring part (6b), and the bottom end of the stirring part (6b) is rotationally connected with the bottom of the reaction vessel (1), the middle part of the blanking part (6a) is rotationally connected with the top of the reaction vessel (1), the bottom is communicated with a plurality of inclined blanking pipes (15), the top of the blanking pipe (15) is communicated with the bottom of the blanking part (6a), the stirring part (6b) is solid, and a driven tooth (16) meshed with the driving tooth (14) is arranged on the blanking part (6 a);

the bottom of the feeding pipe (17) is sleeved at the top of the blanking part (6a), and a bearing (18) and a plurality of shaft seals (19) positioned on the upper side and the lower side of the bearing (18) are arranged between the inner wall of the feeding pipe (17) and the outer wall of the top of the blanking part (6 a);

pass hopper (20), pass hopper (20) and be the ascending loudspeaker form of opening, just the top of passing hopper (20) connect in the inner wall of filling tube (17), the vertical material pipe (21) that pass that is provided with in bottom of passing hopper (20), the external diameter that passes material pipe (21) is less than the internal diameter of blanking portion (6a), just the bottom that passes material pipe (21) is less than the top of blanking portion (6 a).

10. The reaction equipment in the cyclic regeneration process of the lead plaster desulfurizer according to claim 9, wherein the reaction equipment comprises: an annular hollow dispersion pipe (22) is horizontally arranged in the reaction vessel (1), the dispersion pipe (22) is lower than the top of the blanking pipe (15), a connecting pipe (23) with an upper end and a lower end communicated with the circulation pipe (11) and the dispersion pipe (22) is arranged at the top end of the dispersion pipe (22), a plurality of dispersion holes (24) are formed in the bottom of the dispersion pipe (22), and the projection of the blanking pipe (15) in the vertical direction is located in the projection of the dispersion pipe (22) in the vertical direction.

Technical Field

The invention relates to the technical field of recovery of waste lead-acid storage batteries, in particular to a cyclic regeneration process of a lead plaster desulfurizer and reaction equipment thereof.

Background

A lead-acid battery (VRLA) is a battery whose electrodes are made mainly of lead and its oxides and whose electrolyte is a sulfuric acid solution. In the discharge state of the lead-acid battery, the main component of the positive electrode is lead dioxide, and the main component of the negative electrode is lead; in a charged state, the main components of the positive electrode and the negative electrode are lead sulfate.

The waste lead-acid battery is required to be recovered or treated after the service life of the waste lead-acid battery is up, and the lead plaster is required to be subjected to desulfurization treatment in the recovery process of the waste lead-acid battery; the common desulfurization method at present mainly comprises sodium desulfurization and ammonium desulfurization, namely firstly, pre-desulfurization is carried out on lead plaster by adopting a desulfurization transforming agent, and then the desulfurized lead plaster is smelted by a pyrogenic process to produce secondary lead; wherein the main desulfurization transforming agent comprises Na₂CO₃、NH₄HCO₃、(NH₄)₂CO₃And the like. The by-products are all Na₂ SO₄，(NH₄)₂SO₄Usually, the recovery is carried out by an evaporative crystallization system, but the evaporative crystallization process consumes a large amount of energy, so that the desulfurization cost is high.

Disclosure of Invention

The invention aims to provide a cyclic regeneration process of a lead plaster desulfurizer and reaction equipment thereof, and aims to solve the problem of high desulfurization cost.

The technical purpose of the invention is realized by the following technical scheme: a cyclic regeneration process of a lead plaster desulfurizer comprises the following steps:

s1, filtering the desulfurized mixture to obtain filtrate;

s2, adding a precipitating agent into the filtrate to enable the precipitating agent to react with the filtrate and precipitate sulfate ions;

s3, standing and filtering after the reaction is finished, wherein the obtained liquid is the solution of the desulfurizer.

The invention is further provided with: said precipitating agent comprises XCO₃In which XSO₄Is a precipitate, and the XSO₄Has a solubility product less than that of XCO₃The product of solubility of (c).

The invention is further provided with: and X is Ba.

The invention is further provided with: the precipitator is calcium oxide or calcium hydroxide.

The invention is further provided with: the mixture was stirred in said S2.

The invention also provides reaction equipment for realizing the recycling regeneration process of the lead plaster desulfurizer, which comprises the following steps,

the reaction vessel, a liquid inlet pipe communicated with the top of the reaction vessel and a liquid outlet pipe communicated with the bottom of the reaction vessel, wherein a first control valve and a second control valve are respectively arranged on the liquid inlet pipe and the liquid outlet pipe;

the stirring rod is vertically and rotatably arranged in the middle of the reaction vessel, a spiral lifting piece is wound on the outer wall of the stirring rod, and a driving mechanism for driving the stirring rod to rotate is arranged on the reaction vessel;

the air suction pipe is communicated with the top of the reaction vessel, and a third control valve is arranged on the air suction pipe.

The invention is further provided with: the lifting piece and the minimum distance between the axes of the stirring rods are gradually reduced along with the increase of the height, and a plurality of crushing holes are formed in the lifting piece.

The invention is further provided with: the reaction vessel is characterized by further comprising a circulating pipe, wherein two ends of the circulating pipe are respectively communicated with the top and the bottom of the reaction vessel, and a circulating pump is arranged on the circulating pipe.

The invention is further provided with: the driving mechanism comprises a driving motor arranged above the reaction vessel and a driving tooth connected with the driving motor, the stirring rod comprises a hollow blanking part and a stirring part positioned right below the blanking part, the lifting part is positioned on the stirring part, the bottom end of the stirring part is rotatably connected to the bottom of the reaction vessel, the middle part of the blanking part is rotatably connected with the top of the reaction vessel, the bottom of the blanking part is communicated with a plurality of inclined blanking pipes, the tops of the blanking pipes are communicated with the bottom of the blanking part, the stirring part is solid, and the blanking part is provided with a driven tooth meshed with the driving tooth;

the bottom of the feeding pipe is sleeved at the top of the blanking part, and a bearing and a plurality of shaft seals positioned on the upper side and the lower side of the bearing are arranged between the inner wall of the feeding pipe and the outer wall of the top of the blanking part;

the conveying hopper is in a horn shape with an upward opening, the top of the conveying hopper is connected to the inner wall of the feeding pipe, a conveying pipe is vertically arranged at the bottom of the conveying hopper, the outer diameter of the conveying pipe is smaller than the inner diameter of the blanking portion, and the bottom of the conveying pipe is lower than the top of the blanking portion.

The invention is further provided with: the reaction vessel is horizontally provided with an annular hollow dispersion pipe, the dispersion pipe is lower than the top of the blanking pipe, the top end of the dispersion pipe is provided with a connecting pipe, the upper end and the lower end of the connecting pipe are respectively communicated with the circulation pipe and the dispersion pipe, the bottom of the dispersion pipe is provided with a plurality of dispersion holes, and the projection of the blanking pipe in the vertical direction is positioned in the projection of the dispersion pipe in the vertical direction.

The invention has the beneficial effects that: firstly, in the mixture after desulfurization, the granular substance lead carbonate which can be recycled is included, secondly, the components in the filtrate are mainly sodium sulfate or ammonium sulfate, then a precipitator is added into the filtrate to precipitate sulfate radical ions, then the precipitate containing sulfate radical is filtered after standing and filtering, and at the moment, the obtained solution can be used as the desulfurizer again. Because evaporation crystallization is not needed, the investment cost can be well saved, and the desulfurization cost is reduced.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic structural diagram of an embodiment of a reaction apparatus in a recycling process of a lead plaster desulfurizer of the present invention;

FIG. 2 is an enlarged view of portion A of FIG. 1;

FIG. 3 is a first cross-sectional view of an embodiment of a reaction apparatus in a recycling process of a lead paste desulfurizer of the present invention;

FIG. 4 is a second sectional view of an embodiment of a reaction apparatus in the recycling process of a lead paste desulfurizer of the present invention;

FIG. 5 is a third sectional view of an embodiment of a reaction apparatus in the recycling process of a lead paste desulfurizer of the present invention;

FIG. 6 is an enlarged view of portion B of FIG. 5;

FIG. 7 is a schematic structural diagram of an embodiment of a stirring rod and a lifting member in a reaction apparatus in the recycling process of a lead plaster desulfurizer of the present invention;

FIG. 8 is a sectional view of an embodiment of a stirring rod and a lift member in a reaction apparatus in a cyclic regeneration process of a lead paste desulfurizer of the present invention.

In the figure, 1, reaction vessel; 2. a liquid inlet pipe; 3. a liquid outlet pipe; 4. a first control valve; 5. a second control valve; 6. a stirring rod; 6a, a blanking part; 6b, a stirring part; 7. a lifting member; 8. an air exhaust pipe; 9. a third control valve; 10. breaking the holes; 11. a circulation pipe; 12. a circulation pump; 13. a drive motor; 14. a driving tooth; 15. a blanking pipe; 16. a driven tooth; 17. a feed tube; 18. a bearing; 19. shaft sealing; 20. a material conveying hopper; 21. a material conveying pipe; 22. a dispersion pipe; 23. a connecting pipe; 24. a dispersion hole.

Detailed Description

The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.

A cyclic regeneration process of a lead plaster desulfurizer comprises the following steps:

s1, filtering the desulfurized mixture to obtain filtrate;

s2, adding a precipitating agent into the filtrate to enable the precipitating agent to react with the filtrate and precipitate sulfate ions;

s3, standing and filtering after the reaction is finished, wherein the obtained liquid is the solution of the desulfurizer.

The precipitator is calcium oxide or calcium hydroxide.

The mixture was stirred in said S2.

The present invention also provides a reaction apparatus for carrying out the recycling regeneration process of the lead plaster desulfurizer as described in any one of the above, the apparatus being used for the reaction in S2, and having a structure as shown in fig. 1 to 8, comprising,

the reaction vessel comprises a reaction vessel 1, a liquid inlet pipe 2 communicated with the top of the reaction vessel 1 and a liquid outlet pipe 3 communicated with the bottom of the reaction vessel 1, wherein a first control valve 4 and a second control valve 5 are respectively arranged on the liquid inlet pipe 2 and the liquid outlet pipe 3;

the stirring rod 6 is vertically and rotatably arranged in the middle of the reaction vessel 1, a spiral lifting piece 7 is wound on the outer wall of the stirring rod 6, and a driving mechanism for driving the stirring rod 6 to rotate is arranged on the reaction vessel 1;

the extraction tube 8 is communicated with the top of the reaction vessel 1, and a third control valve 9 is arranged on the extraction tube 8.

The minimum distance between the lifting piece 7 and the axis of the stirring rod 6 is gradually reduced along with the increase of the height, and a plurality of crushing holes 10 are formed in the lifting piece 7.

The reaction vessel further comprises a circulating pipe 11, two ends of the circulating pipe 11 are respectively communicated with the top and the bottom of the reaction vessel 1, and a circulating pump 12 is arranged on the circulating pipe 11. The driving mechanism comprises a driving motor 13 arranged above the reaction vessel 1 and a driving tooth 14 connected with the driving motor 13, the stirring rod 6 comprises a hollow blanking part 6a and a stirring part 6b positioned right below the blanking part 6a, the lifting piece 7 is positioned on the stirring part 6b, the bottom end of the stirring part 6b is rotatably connected to the bottom of the reaction vessel 1, the middle part of the blanking part 6a is rotatably connected with the top of the reaction vessel 1, the bottom of the blanking part is communicated with a plurality of inclined blanking pipes 15, the top of each blanking pipe 15 is communicated with the bottom of the blanking part 6a, the stirring part 6b is solid, and the blanking part 6a is provided with a driven tooth 16 meshed with the driving tooth 14;

the bottom of the feeding pipe 17 is sleeved at the top of the blanking part 6a, and a bearing 18 and a plurality of shaft seals 19 positioned on the upper side and the lower side of the bearing 18 are arranged between the inner wall of the feeding pipe 17 and the outer wall of the top of the blanking part 6 a;

pass hopper 20, pass hopper 20 and be the ascending loudspeaker form of opening, just the top of passing hopper 20 connect in the inner wall of filling tube 17, the vertical material pipe 21 that passes that is provided with in bottom of passing hopper 20, the external diameter of passing material pipe 21 is less than the internal diameter of blanking portion 6a, just the bottom of passing material pipe 21 is less than the top of blanking portion 6 a.

An annular hollow dispersion pipe 22 is horizontally arranged in the reaction vessel 1, the dispersion pipe 22 is lower than the top of the blanking pipe 15, a connecting pipe 23 is arranged at the top end of the dispersion pipe 22, the upper end and the lower end of the connecting pipe 23 are respectively communicated with the circulation pipe 11 and the dispersion pipe 22, a plurality of dispersion holes 24 are formed in the bottom of the dispersion pipe 22, and the projection of the blanking pipe 15 in the vertical direction is located in the projection of the dispersion pipe 22 in the vertical direction.

According to the reaction equipment in the process of recycling the lead plaster desulfurizer, firstly, a granular substance lead carbonate capable of being recycled is contained in a mixture after desulfurization, secondly, the components in a filtrate are mainly sodium sulfate or ammonium sulfate, then a precipitator is added into the filtrate to precipitate sulfate ions, then, after standing and filtering, the precipitate containing sulfate ions is filtered out, and at the moment, the obtained solution can be used as the desulfurizer again. Because evaporation crystallization is not needed, the investment cost can be well saved, and the desulfurization cost is reduced.

Wherein, after the calcium oxide powder is added into the filtrate, firstly, the calcium oxide powder reacts with water to generate calcium hydroxide, then, the ammonium sulfate reacts with the calcium hydroxide to generate calcium sulfate which is slightly soluble in water, and simultaneously, ammonia gas is generated (if the amount of the ammonia gas is less, the ammonia gas is directly dissolved into the liquid to become ammonia water which can be mixed with lead plaster after becoming the ammonia water, the liquid formed by mixing the lead plaster and the carbon dioxide carry out a plurality of times of circulating reactions, and in the reaction process, the carbon dioxide, the ammonia water and the lead plaster react to generate lead carbonate, thereby achieving the effect of desulfurization, as detailed in the other two patents of the lead plaster desulfurization process and the desulfurization equipment thereof and the desulfurization mixer, the ammonia gas, the ammonia water or ammonium ions can be recycled, the regeneration effect is achieved, and moreover, the commercial value of the calcium sulfate is higher, so that the value can be generated, meanwhile, evaporation and crystallization are not needed to recover ammonium sulfate, so that the cost and energy consumption are greatly reduced, and the concept of environmental protection is better met; however, if the amount of ammonia is large, the ammonia can be extracted through the extraction pipe 8 after opening the third control valve 9, and then dissolved with water to form ammonia water outside or directly dissolved in water with lead paste).

In the process of stirring reaction, materials can be contacted more fully, the reaction rate is improved, and meanwhile, because the lifting piece 7 is spiral, when the lifting piece 7 is used for stirring liquid to react, the lifting piece 7 can lift the liquid at the bottom to a high position to react; the method has the advantages that firstly, part of unreacted powdery substances can be lifted to a high position for reaction, and secondly, liquid can be stirred, so that calcium sulfate adhered to the surface of calcium oxide powder falls off, and the internal calcium oxide can contact with water for subsequent reaction; wherein, because the lifting member 7 and the stirring rod 6 are gradually reduced along with the increase of the height, a circular convection current is formed between the middle part of the reaction vessel 1 and the inner wall, namely, the middle part continuously has upward flowing force, but the liquid in the middle has a tendency of flowing towards the periphery because the periphery of the top of the liquid is subjected to smaller flowing force, so the whole body shows that the liquid per se is also overturned, and the reaction can be better and more thoroughly carried out. Wherein at broken hole 10 on lifting member 7, liquid is when passing broken hole 10, because its velocity of flow is great at first, secondly still produce mutual effect with the surface of lifting member 7 or the inner wall in broken terror hole easily, so also can make the better crushing of particulate matter, guaranteed that the reaction can high-efficiently go on, and more thorough going on.

Furthermore, in the reaction process, the circulating pump 12 and the circulating pipe 11 enable the liquid to flow out from the bottom of the reaction vessel 1 and then flow back to the reaction vessel 1 through the top, so that even if the bottom is remained, the liquid can be returned to the reaction vessel 1 again, and meanwhile, in the process of returning to the reaction vessel 1, the liquid can be impacted, so that the materials are more uniform and dispersed.

When the stirring rod 6 rotates, firstly, the driving gear 14 is driven by the driving motor 13 to rotate, then the driven gear 16 is driven by the driving gear 14 to rotate, the stirring rod 6 is driven by the driven gear 16 to rotate, wherein the bottom of the stirring rod 6 is also rotationally connected with the bottom of the reaction vessel 1, so that the position stability and the rotational stability of the stirring rod 6 are improved.

When the stirring rod 6 rotates, the feeding pipe 17 does not rotate, but because the bottom end of the feeding pipe 17 is in sealed connection with the top of the blanking part 6a through the bearing 18 and the shaft seal 19, the materials can be prevented from spilling to the outside firstly, the ammonia gas can be prevented from overflowing, and meanwhile, the rotation of the blanking part 6a is not limited by the feeding pipe 17. The blanking part 6a drives the stirring part 6b to rotate, and the stirring part 6b drives the lifting piece 7 to rotate. Meanwhile, the materials firstly enter the cavity of the blanking part 6a through the feeding pipe 17 with an immovable position and then fall to the bottom of the blanking part 6a under the action of the gravity of the materials, and the materials can fall out of the blanking pipe 15 into the reaction vessel 1 under the action of the gravity because the blanking pipe 15 is inclined. Because blanking portion 6a and blanking pipe 15 are all rotating, so can be fine with powdered calcium oxide (or other precipitant) spill in reaction vessel 1 for the reaction can very high-efficient go on, simultaneously because the powder is the scattering state, so prevent that the precipitant from taking place the caking etc..

Moreover, when the precipitator enters the blanking portion 6a from the feeding pipe 17, the precipitator passes through the material conveying hopper 20 and the material conveying pipe 21, firstly, the top of the material conveying hopper 20 is connected to the inner wall of the feeding pipe 17, so that the sufficient material can be ensured to fall into the material conveying pipe 21, and meanwhile, the precipitator can be prevented from falling to the shaft seal 19 because the material conveying pipe 21 is positioned in the feeding pipe 17, so that the material waste is prevented, and the normal use of the shaft seal 19 and the like is ensured; and because a small gap is formed between the outer wall of the material conveying pipe 21 and the inner wall of the blanking part 6a, firstly, the two materials cannot be abraded, and secondly, the materials can be well prevented from falling onto the shaft seal 19.

When the liquid pumped up by the circulating tube 11 flows out from the circulating tube 11, the liquid firstly enters the connecting tube 23, then enters the dispersion tube 22 from the connecting tube 23, and then flows out to the reaction vessel 1 through the plurality of dispersion holes 24; the dispersion holes 24 can further disperse all the liquid, so that various reactions can be carried out more uniformly, and the reaction efficiency is improved as a whole; secondly, because the dispersion pipe 22 is higher than the top of the blanking pipe 15, and the outlet of the blanking pipe 15 is located in the inner diameter of the dispersion pipe 22, after the powder falls out of the blanking pipe 15, the powder will continue to move outwards under the action of inertia, and at this time, the powder will interact with the liquid flowing out of the dispersion hole 24, so that the dispersion effect of the powder is better.

In yet another embodiment, the precipitating agent comprises XCO₃In which XSO₄Is a precipitate, and the XSO₄Has a solubility product less than that of XCO₃The product of solubility of (c). X is Ba, thus XCO₃Is actually BaCO₃And (3) powder. Of course, other substances which can precipitate sulfate ions can also be selected. Wherein the value of barium sulfate is higher than that of barium carbonate, thus the desulfurizing agent is recycled and simultaneously the desulfurizing agent is generatedThe extra output value and the economic benefit are better.

In yet another embodiment, the precipitant is calcium hydroxide powder.

It should be noted that, in the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments may be referred to each other.

The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.