WO1988008052A1

WO1988008052A1 - Asphaltic concrete production apparatus

Info

Publication number: WO1988008052A1
Application number: PCT/IT1987/000081
Authority: WO
Inventors: Antonio Cipriani; Marino Torsello
Original assignee: Marini S.P.A.
Priority date: 1987-04-16
Filing date: 1987-09-12
Publication date: 1988-10-20
Also published as: EP0362199A1; AU8032187A; DE3778035D1; EP0362199B1; EP0362199B2; ES2010257A6

Abstract

Asphaltic concrete apparatus for the production of ready-mix asphaltic concrete, using rotatable mixing drum means (1, 1') having a flow of combustion gas in countercurrent by a downstream placed burner means delivering the combustion gases inside the respective rotatable mixing drum means (1, 1'), in which the rotatable mixing drum means (1, 1') is divided in two chambers: the first one ''R-V'' for supplying, advancing and drying the inert virgin material (2) and eventually with the recyclable asphaltic product (R.A.P. 12); the second one for further advancing, impregnating and mixing the dried material from the first one with bituminous and filler substances (binders) ''W''; the respective flame of said burner means (116-119-117, 16-15-14) being axially delivered inside the first one ''R-V''.

Description

ASPHALTIC CONCRETE PRODUCTION APPARATUS

The subject of the present invention is an apparatus for drying and mixing inert material and/or recyclable asphaltic product (R.A.P.), with bituminous and non bituminous materials in an elongated rotatable drum means, in which inert material composition is introduced at a first end and recovered at the opposite second end, and having a burner nozzle or the combustion chamber or its closed extension, extending into the drum and directing the hot gases countercurrent to the advancing materials into the drum means.

The invention has a convenient although not exclusive application for the production of asphaltic concrete as a ready bituminous mix, in particular for road paving. The countercurrent solution is known in the present state of art: US 4,522,498 (USA application n. 139,708 filed on Apr.,14,1980 in the name of Mendehall). This solution proposes an apparatus for recycling asphaltic concrete, comprising an elongated rotatable drum in which composition is introduced at a first end and recovered at the opposite second end, and having a burner extending into the drum so that the burner nozzle is located within the drum in intermediate position between the first and second ends and directs the hot gases toward the first end, and wherein the portion of the drum between the burner and the first end is provided with lifters of a type which prevent the formation of a veil of composition particles from falling through the hot gases of combustion as the drum is rotated, and a second portion between the burner nozzle and the second drum end and which is provided with lifters which cause a veil of composition particles to pass through hot gases of combustion as the drum rotates. Another solution for recycling asphaltic product with inert virgin material is proposed by the same applicant with IT-5031B/84 (MARINI application of 10.9.84) regarding a "Drier with recycling of salvage asphaltic concrete material for bituminous mix apparatus". Said drier foresees the use of a rotatable drum which is preferably slightly tilted in respect to the horizontal plane, having finning-lifters for inside mixing, where inert virgin material (e.g. gravel not impregnated with bituminous substances) is charged upstream (at the first end of the drum) and where the mouth of a burner is arranged downstream immediately inside the drum, the flame of which is directed axially in countercurrent in respect to the said inert material advancing from upstream drum end, and where recyclable asphaltic product (R.A.P.) is charged, in a position immediately upstream in respect to said burner head or nozzle, so that a new dried mix of reutilisable inert product is discharged downstream.

Both in the first solution (US-4522498) and in the second one (IT- 5031 B/84), the product can be discharged dried (without further addition of bituminous asphalt substances and other filler impregnating binders) to be then utilized at the desired moment, after a successive impregnation with impregnating bituminous substances and fillers, by a second mixing drum apparatus, allowing to addition the the "binders" to the respective inert dried product so as to obtain the ready-mixed bituminous mix of asphaltic concrete ready to be utilized.

The main disadvantage of this solution concerns the fact that requires two drum apparatuses: - the first one for drying the inert material and eventually mix the virgin inert material with recyclable asphaltic product (R.A.P.); - the second one for impregnating and mixing the respective dried product obtained by the first one, with liquid and or semiliquid bituminous and filler substances (binders).

Of course a single asphaltic concrete production drum means can be realized, but this apparatus will be complex and too long. The problem being to realize a single universal apparatus, simple and very short, allowing to dry in a single drum apparatus, inert virgin material and eventually recyclable asphaltic product (R.A.P.) and impregnate and mix it with binding materials such as bituminous substances and fillers (binders) to realize a ready to use asphaltic concrete.

Further the above-mentioned patent disclosures do not solve the inconvenience which derives from the fact that the proportion between the virgin material and the material to be recycled (R.A.P.) is not constant, as the apparatus must generally be able to realize a product in which the recyclable asphaltic product (R.A.P.) can be absent or can be added in quantities which may also be identical to those of the inert virgin material. It follows that the first portion heating the inert virgin material is interested by a rate of virgin material which is as high as is the ratio between the virgin material/R.A.P.. The consequence being a noticeable variation of the respective filling level. Said "filling level" is one of the fundamental parameters which influence the thermal exchange between the combustion gases and the advancing materials, and thereby the overall efficiency of the machine. As the filling level depends on the slope of the drum and on its speed of rotation, it is impossible in a single unit to act on one of these parameters so as to optimize the performances of the first section without simultaneously influencing the successive section where the virgin material is mixed with the R.A.P. The problem to be solved becomes more complex if after mixing and drying inert virgin material with R.A.P. it is intended to impregnate and mix the dried material with the bituminous/filler binder substances which, on the other hand, needs to treat a nearly constant flow of material even if the ratio of inert virgin material/R.A.P. varies, the other conditions naturally remaining unvaried.

The scope of this invention is to eliminate said inconveniences and solve the respective problems which they raise.

According to the characteristics given in the attached claims, this invention solves the problems by using an apparatus of the type for the production of ready-mix asphalt composition concrete, using rotatable mixing drum means having a flow of combustion gas in countercurrent by a downstream placed burner means delivering the combustion gases inside the respective rotatable mixing drum means, in which the rotatable mixing drum means is divided in two chambers: - the first one for supplying, advancing and drying the inert virgin material and eventually with the recyclable asphaltic product (R.A.P.); - the second one for further advancing, impregnating and mixing the dried material from the first one with bituminous and filler substances (binders); - the respective flame of said burner means being axially delivered inside the first one. With this solution a very simple and short asphaltic concrete production apparatus can be realized. Advantageously the two chambers are divided by a diaphragm with adjustable door openings allowing the material to pass from the first one to the second one by the falling-rolling, advancing movement of the material. With this solution, the firing of the material in the impregnating and mixing chamber (second one) is prevented because the respective diaphragm and the suction action of the countercurrent combustion gases developed and delivered in the first chamber, further allow to suck developed inflammable gas from the second one.

In order to allow mixing in the first chamber (drying chamber) of the inert virgin material with recyclable asphaltic product (R.A.P.), the rotatable drum apparatus is divided in two portions "R'V'S", by an intermediate anular R.A.P. charging hopper, the second portion being divided in two sections "V"+"W", the second section being said impregnating and mixing chamber, wherein: - the first portion "R" is provided with finning means for inside lifting advancing and mixing inert virgin material supplied at the first end of the rotatable drum apparatus, and - the first section "V" of the second portion "S" is provided with finning means for inside lifting, advancing and mixing inert virgin material supplied from the first portion "R" with recyclable asphaltic product (R.A.P.) supplied by said intermediate anular charging hopper. With this solution a compact, not expensive and very efficient asphaltic concrete production apparatus is realized.

In a preferred embodiment the rotatable drum means is divided in two rotatable drum parts although it realizes the continuity of the chamber for the progress and mixing of the materials, the first part comprising a first portion "R" which substantially interests the drying of the virgin material and the second part comprising a second portion "S" divided in two sections "V"+"W", being; - the first section "V" substantially interesting the introduction of the R.A.P., heating and mixing it with the inert virgin material and - the second section "W" for impregnating and mixing the dried materials from the first section "V", with binding substances e.g. bituminous and filler materials, - each drum being equipped with rotating means allowing different speeds. The advantages of this solution, consist in the possibility of being able to operate the apparatus in the optimal manner depending on the- proportions of the materials used and on the resulting ready to use asphaltic concrete mix desired.

In a further preferred embodiment the burner is elongated axially inside and across the second section "W", the respective combustion happening or being extended in the first section "V". This solution having the advantage of simplicity.

In an alternative solution the burner is placed downstream outside the rotatable drum means and the combustion gas chamber is extended inside and across the second section "W" with opening in the first section "V". This solution having the advantage of long life and easy maintenance of burner means.

The invention is hereafter explained in more detail with the help of the drawings showing the preferential realization solutions, the execution details of which are not to be held as limiting but only as examples. - Figure 1 shows a schematic axial section view of the rotatable drum apparatus in a first embodiment with burner extended inside the drum having a diaphragm in the combustion opening, dividing the drum in two chambers, the combustion chamber being realized in the first chamber where inert virgin material is advanced and dried, the second chamber providing the bituminous and filler binding liquid materials. - Figure 2 shows a schematic axial section view of the rotatable drum apparatus as represented in Figure 1 with R.A.P. intermediate charging hopper. - Figure 1A shows a schematic axial section view of the rotatable drum apparatus with R.A.P. intermediate charging hopper in a further embodiment by positioning the burner downstream of the rotatable drum and extending the respective combustion chamber inside it. - Figure 1 B shows a schematic axial section view of the rotatable drum apparatus in in a further embodiment by utilizing a single rotatable drum and positioning the burner downstream of the rotatable drum and extending the respective combustion chamber inside it. - Figures 2A and 3A, give the respective schematic transverse sections view of the rotatable drum of Figure 1A and 1 B, as per plans X-X and Y-Y of the first and second chamber respectively. - Figure 4 shows a schematic axial section view of the rotatable drum apparatus with R.A.P. intermediate charging hopper as represented in Figure 1A, the respective drum means being divided in two independent rotatable drums, the division being realized downstream of the R.A.P. intermediate charging hopper. - Figure 1 C shows a schematic axial section view of the rotatable drum apparatus in n a further embodiment by utilizing two independent rotatable drums and extending the burner axially inside the second drum. - Figures 2C,3C,4A give the respective schematic transverse sections view of the rotatable drum means of Figure 1C, as per plans X-X in the first drum, Z-Z and Y-Y in the second drum.

With reference to the figures, it can be seen that the apparatuses comprise a single rotatable drum (1) alternatively a pair of rotatable drums (1 ,1 ') rotated by crown pinion means (109/110,17,17') supported on roller means (106/104-107/105,18,18') with an inlet mouth for inert virgin material hopper supply, placed upstream at the first end of the rotatable drum means (113,2) which pours the inert virgin material into a feeding area having helicoidal feeding blades (114,3) and then passes to a drying area having lifting finnings in the form of cups for a continuous fall of material (115,4) which constitute the first portion "R", and more extended or more tightly closed finning-cups (1 15a, 6,7), being provided downstream in a further portion "S", in order to allow the advancing material to be lifted and advanced, of the type which prevent the formation of a veil of inert particles from falling through the hot gases of combustion as the drum is rotated, to obtain an undisturbed combustion, leaving a free central axial space which has a more ample diameter in respect to the first portion "R", realizing a first section "V" where R.A.P. can be added (19). The first portion "R" and the first section "S" realizing a first chamber in the rotatable drum means where the inert material will be dried and eventually mixed with R.A.P.

The possibility of inserting the material to be recycled R.A.P. (12) can be realized at the end of the first portion "R" (1 l5a,19) by an intermediate annular stationary introducing hopper (126) extending anularly in an external ring form (127,5), by means of helicoidal introducing channels realized by external finnings fixed to the rotating drum, closed externally by a fixed openable cylindrical carter (29) in order to convey the respective R.A.P. inside the rotatable drum across a plurality of circumferential openings (130) realized in the rotatable drum (1 ).

Advantageously, after the R.A.P. introducing hopper (126-127- 129,12,5), a second coaxial independent rotatable drum (1 ') with independent rotating means (17') can be realized (Fig.4-Fig.1C).

After said first section "V" a second section "W" to impregnate and mix the dried product coming from the previous section "V" with binding bituminous and filler substances by means of a suitable lower delivery nozzle means (123-124, 13) is arranged behind the burner's flame delivery mouth of the respective burner means (117-1 16-1 19,14, 14-15-16) so as to avoid danger of combustion.

The bound asphaltic concrete will be discharged downstream at the second end of the rotatable drum means, through a ring head (125,11) with the discharge outlet of the ready-mix composition, positioned downwards (8), whereas the combustion gases will be discharged upstream at the first end of the rotatable drum means by a flue ( 111-112, 9-10 ) . It will be noted that in the first portion "R" , after the inert virgin material feeding bladess (114,3), the respective advancing finning means (1 15,4) is realized in form of semi-opened cups (4 Figures 2A-2C) suitable for the realization of a continuous fall of material through the combustion gases whereas the finning means of the first section "V" (115a- 6) is more tightly closed in order to determine, as explained, a free axial space for the combustion (Figures 3A-3C). Downstream of the advanced burner head (14) and in any case, behind the respective flame, the respective finning means will conveniently be radial (7) so as to obtain the final mixing of the various materials without collision with the respective burner duct means (116-119,14,16).

In order to prevent fire in the impregnating and mixing chamber (second chamber "W"), the two chambers "R+V" and "W", are divided by a diaphragm (118) with adjustable door openings (120) allowing the material to pass with adjustable rate from the first one to the second one by the falling-rolling advancing movement by cooperating upstream helicoidal feeders (121 ).

Advantageously both the said first portion "R" and the said first section "V" of the said first chamber, present finning means (115-115a,4-6) which are substantially bent with a progressive tendency to parallelism with the inside cylindrical surface of the chamber (4,6), those of the said downstream first section "V" being more closed than those of the first portion "R".

Claims

1 . Asphaltic concrete apparatus for the production of ready-mix asphaltic concrete, using rotatable mixing drum means having a flow of combustion gas in countercurrent by a downstream placed burner means delivering the combustion gases inside the respective rotatable mixing drum means, characterized by the fact that the rotatable mixing drum means is divided in two chambers: - the first one "R-V" for supplying, advancing and drying the inert virgin material (2) and eventually with the recyclable asphaltic product (R.A.P. 1 2) ; - the second one for further advancing, impregnating and mixing the dried material from the first one with bituminous and filler substances (binders) "W"; - the respective flame of said burner means (1 16-1 19-117, 16-15-14) being axially delivered inside the first one "R-V".

2. Asphaltic concrete apparatus as per claim 1., characterized by the fact that the two chambers "R+V" and "W", are divided by a diaphragm (118) with openings (120) cooperating with upstream helicoidal feeders (121) allowing the material to pass from the first one chamber to the second one chamber by its falling-rolling, advancing movement.

3. Asphaltic concrete apparatus as per claim 1 ., characterized by the fact that the two chambers "R+V" and "W", are divided by a diaphragm (118) with adjustable openings (120) cooperating with upstream helicoidal feeders (121 ) allowing : - the material to pass from the first chamber to the second chamber by its falling-rolling, advancing movement; - to vary the respective rate of material passing from the first chamber to the second chamber.

4. Asphaltic concrete apparatus as per claim 1., characterized by the fact that the rotatable drum apparatus (1) is divided in two portions "RVS", by an intermediate anular R.A.P. charging hopper (126-127-128-129-130, 5,19), the second portion "S" being divided in two sections "V"+"W", the second section being said impregnating and mixing chamber of dried material from said first chamber, wherein: - the first portion "R" is provided with finning means (114-115,3-4) for inside lifting advancing and mixing inert virgin material supplied at the first end (113,2) of the rotatable drum apparatus (1), and - the first section "V" of the second portion "S" is provided with finning means (1 15a, 6) for inside lifting, advancing and mixing inert virgin material supplied from the first portion "R" with recyclable asphaltic product (R.A.P.12) supplied by said intermediate anular charging hopper (1 26-1 27-1 28-129-130, 5,1 9) .

5. Asphaltic concrete apparatus as per claim 1., characterized by the fact that the rotatable drum means is divided in two rotatable drum parts (1 ,1') although it realizes the continuity of the chamber for the progress and mixing of the materials, the first part (1 ) comprising a first portion "R" which substantially interests the drying of the virgin material and the second part (1 ') comprising a second portion "S" divided in two sections "V"+"W", being: - the first section "V" substantially interesting the introduction of the R.A.P. (12), heating and mixing it with the inert virgin material (113,2) and - the second section "W" for impregnating and mixing the dried materials from the first section "V", with binding substances e.g. bituminous and filler materials (123-124,13), - each drum (1 ,1 ') being equipped with rotating means (17,17') allowing different speeds.

6. Asphaltic concrete apparatus as per claim 1., characterized by the fact that the burner means comprises a burner (116-117,14) elongated axially inside and across the second section "W", the respective combustion happening or being extended in the first section "V".

7. Asphaltic concrete apparatus as per claim 1., characterized by the fact that the burner means comprises a burner (14) placed downstream, outside the rotatable drum means (1 ,1') and the combustion gas chamber (T5.16) is extended inside and across the second section "W" with opening in the first section "V".

8. Asphaltic concrete apparatus as per claim 1., characterized by the fact that in the first portion "R" of said first chamber, upstream inert virgin material feeding bladess in helicoidal form is provided (1 14,3) and respective lifting and advancing finning means, realized in form of semi-opened cups (1 15,4) suitable for' the realization of a continuous fall of material through the combustion gases is further provided.

9. Asphaltic concrete apparatus as per claim 1., characterized by the fact that downstream of the advanced burner head (14) and in any case, behind the respective flame, the respective finning means will conveniently be radial (7) .

10. Asphaltic concrete apparatus as per claim 1., characterized by the fact that in the internal cylindrical wall of said first chamber: - a portion of finning lifting means (115,4) for a continuous fall of the inert virgin material through the combustion gases is provided and - a further portion of finning lifting means downstream the first ones placed (115a,6), to avoid a continuous fall of material in front of the combustion area, preventing a formation of veil of particles from falling through the hot gases of combustion as the drum is rotated, is further provided.

11. Asphaltic concrete apparatus as per claim 1., characterized by the fact that the internal cylindrical wall of said first chamber comprises finning lifting means (1 15-1 15a,4-6) which are substantially bent with a progressive tendency to parallelism with the inside cylindrical surface of the rotating chamber.

12. Asphaltic concrete apparatus as per claim 1., characterized by the fact that the internal cylindrical wall of said first chamber comprises finning lifting means (1 15-1 15a,4-6) which are substantially bent with a progressive tendency to parallelism with the inside cylindrical surface of the rotating chamber, being said finning lifting means (115-115a,4-6) divided in two portions wherein the downstream portion (115a,6) is more close to the inner cylindrical surface than the upstream portion (115,4).