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Title:
METHOD OF DELIVERING MATERIAL AND WASTE TREATMENT
Document Type and Number:
WIPO Patent Application WO/2013/014495
Kind Code:
A1
Abstract:
The invention provides for a method of delivering material to a unit (10) operable to be fired and to a method of treating waste material which includes the delivery method. The delivery method includes encasing masses of material in casings to produce articles of encased material (20) and feeding the articles (20) into the unit (10) by conveying the articles (20) with a fluid that projects the articles into the unit (10).

Inventors:
SCHOONRAAD JOHAN LAURENCE (ZA)
Application Number:
IB2011/053340
Publication Date:
January 31, 2013
Filing Date:
July 27, 2011
Export Citation:
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Assignee:
ENVIROSERV WASTE MAN PROPRIETARY LTD (ZA)
SCHOONRAAD JOHAN LAURENCE (ZA)
International Classes:
F23G5/44; F23G5/20
Foreign References:
US5086716A1992-02-11
US5549058A1996-08-27
JP2008249194A2008-10-16
Other References:
None
Attorney, Agent or Firm:
VAN DER WALT, Louis, Stephanus et al. (PO Box 1014, 0001 Pretoria, ZA)
Download PDF:
Claims:
CLAIMS:

1 . A method of delivering material to a unit operable to be fired, which method includes:

encasing masses of material in casings to produce articles of encased material ; and

feeding the articles into the unit by conveying the articles with a fluid that projects the articles into the unit. 2. A method as claimed in claim 1 , in which the fluid is air.

3. A method as claimed in claim 1 or claim 2, in which the fluid is pressurised.

4. A method as claimed in claim 3, which includes compressing the fluid prior to conveying the articles with the fluid.

5. A method as claimed in any of claims 1 to 4, in which the unit is a rotary kiln.

6. A method as claimed in any of claims 1 to 5, in which the masses of material are encased by a non-chlorinated substance or composition which is selected from the group consisting of a polymeric plastics material, a wood fibre-based material, a cellulosic material and a plasticized cardboard composite.

7. A method as claimed in any of claims 1 to 6, in which the encasing of the material is by means of an automated packaging machine.

8. A method as claimed in any of claims 1 to 7, in which the articles are generally right circular cylindrical in shape and the casings are close-fitting wrappings of a flexible, polymeric plastics material.

9. A method as claimed in any of claims 1 to 8, in which the mass of each article is 50 g - 3 kg.

10. A method as claimed in any of claims 1 to 9, in which the material includes a carbonaceous substance or composition which is selected from the group consisting of

011, tar, tallow, grease, coal dust, lubricant, cheese, chocolate, corn syrup, honey, molasses, solvents, carcasses, and two or more thereof.

1 1 . A method as claimed in any of claims 1 to 10, in which the material is admixed with a substance or composition selected from the group consisting of an absorbent, an adsorbent and a filler, and two or more thereof.

12. A method as claimed in any of claims 1 to 1 1 , in which the material is a non- solid, non-gaseous material.

13. A method of treating waste material, which method includes:

delivering, by means of a method as claimed in any one of claims 1 to 1 2, the material to a unit operable to be fired; and

allowing the material to be chemically transformed in the unit when the unit is fired.

Description:
METHOD OF DELIVERING MATERIAL AND WASTE TREATMENT

THIS invention relates to a method of delivering material and waste treatment. In particular, the invention relates to a method of delivering material to a unit operable to be fired and to a method of treating waste material which includes the delivery method.

Various attempts have been made to operate furnaces and kilns on inexpensive fuels, for example high calorific waste, also known as Alternative Fuel Resources (AFR). For example, AFR, such as used tyres, have been supplied to rotary cement kilns via a chute located along the body of the kiln and/or at the kiln material feed end (or cold end). The point of addition of the AFR is fixed to where the chute is installed. Where the AFR is required to be added at a certain location in the kiln, the modification of the kiln body to accommodate a chute impairs the integrity of the kiln body and can result in high maintenance costs and down time. Where the chute is on the body of a rotary kiln, AFR can only be fed once per revolution of the kiln when the hatch on the kiln aligns with the chute. The quantity of AFR required per revolution must all be added at a single point in time. This creates a spike of energy and false air flows which create process upsets.

Another method to add a fuel is to feed the fuel by atomisation. This can sometimes work well for liquid materials. However, a significant solid content, especially abrasive solids, can cause high wear rates of the atomisation nozzle, which can negatively impact the economical and sustained use of such materials as a fuel. The use of a secondary furnace or kiln, which has for example been used for oil drilling muds whereby combustion of the drilling muds take place in the secondary kiln and hot gas from the secondary kiln is fed to a primary kiln, entails high capital and maintenance costs. Further, the destruction of diseased carcasses in a rotary cement kiln currently requires the separation of the liquid oil/fat from solid material for separate delivery into the kiln. The solid material is often dried. This process is expensive and time consuming. This invention seeks to mitigate or avoid these problems, at least to some extent. Further advantages of the invention will appear from what is set out below.

In this specification "encased" means enclosed within a casing.

In this specification "waste" includes, without limitation, refuse, material left over from a process of manufacture or the use of consumer goods, damaged or discarded material, a by-product from an industrial process which would otherwise have been discarded or destroyed or animal carcasses which would otherwise have been discarded or destroyed.

In this specification "carbonaceous" means consisting of or containing carbon.

According to a first aspect of the invention there is provided a method of delivering material to a unit operable to be fired, which method includes:

encasing masses of material in casings to produce articles of encased material ; and

feeding the articles into the unit by means of conveying the articles with a fluid that projects the articles into the unit.

The unit may be a furnace or kiln.

The masses of material may be encased at a location that is proximate to or remote from the unit.

In one embodiment of the invention, the fluid is air

The fluid may be pressurised. The rate of delivery of the articles into the unit can be controlled by varying the relative proportions of the articles and the fluid. The appropriate placement of the articles in the unit can be conveniently achieved by using pressurised fluid of an appropriate pressure for the mass and shape of the articles. Instead, the appropriate placement of the articles in the unit can be achieved by varying the volume of fluid released, for example by means of an accumulator and/or the use of a valve. The method may include compressing the fluid prior to conveying the articles with the fluid.

It will be appreciated that for efficient combustion, the combustion of the articles in the unit should take place at a high enough temperature. Thus, preferably the articles are introduced into the unit at positions in the unit where combustion can take place at an optimal temperature for efficient combustion.

The unit may be a rotary kiln, for example a cement rotary kiln, a ferro- alloy rotary kiln or a calcining rotary kiln. The articles are preferably introduced into the kiln at a feed end and/or at a discharge end of the kiln, thereby to avoid impairment to the integrity of a body of the kiln caused by the modifying of the kiln body to include a feed pipe for the articles. Kilns are often provided with a plurality of burner feed pipes and, in use, one of them is typically selected for introducing burner fuel for igniting the burner (hereinafter referred to as burner fuel). The articles may conveniently be introduced into the kiln via one of the burner feed pipes of the kiln that is not being used for introducing burner fuel for igniting the burner. It will be appreciated that conventional kilns can be retro-fitted by means of relatively minor modifications and at relatively low cost and low down time, to enable the introduction of a fluid carrying the articles into the kiln.

The method may include encasing the material by a non-chlorinated substance or composition which is selected from the group consisting of a polymeric plastics material, a wood fibre-based material, a cellulosic material and a plasticized cardboard composite.

The masses of material may be encased manually or by means of a manually-operated packaging machine or an automated packaging machine. The masses of material may be encased in casings such as bottles, jars, tubes, cartons, receptacles, bags or skin coverings. The casings may be flexible. Preferably, the articles each have a cross-section which is generally circular in outline, thereby to facilitate conveying of the articles along a pipe by the fluid. For example the articles may be generally right circular cylindrical in shape and the casings may be close-fitting wrappings of a flexible, polymeric plastics material. The casings may be filled with material by means of continuous, semi-continuous or batch filling. The casings may be sealed by means of a cap, tie, crimp, plug, clamp or heat seal. The packaging machine may for example be a sausage packaging machine, a form, fill and seal machine or a liquid dispensing machine. The mass of each article is preferably 50 g - 3 kg.

The material may include a carbonaceous substance or composition. The carbonaceous substance or composition may be selected from the group consisting of oil, tar, tallow, grease, coal dust, lubricant, cheese, chocolate, corn syrup, honey, molasses, solvents, carcasses, and two or more thereof. The material may be admixed with a substance or composition selected from the group consisting of an absorbent, an adsorbent, a filler, and two or more thereof. It will be appreciated that the chemical content of the material may be modified to suit whatever process is to take place in the unit. Thus, if a particular substance or composition is needed for a process to take place in the unit, the substance or composition may be admixed with the material. It will further be appreciated that the encasing of the material means that even relatively abrasive material, for example material containing fine ash, a fine iron content or catalyst dust and silicates, can be used without causing undue wear to the unit and/or its delivery system.

In one embodiment of the invention, the material is a fluid, in particular a liquid or gel or sludge or the like, i.e. a non-solid, non-gaseous material. The material may thus be a high viscosity hydrocarbon liquid or a hydrocarbon sludge. According to a second aspect of the invention there is provided a method of treating waste material, which method includes:

delivering the material to a unit operable to be fired by means of a method which includes:

encasing masses of material in casings to produce articles of encased material; and feeding the articles into the unit by means of conveying the articles with a fluid that projects the articles into the unit; and

allowing the material to be chemically transformed in the unit when the unit is fired. The method of treating waste material may include any of the further features hereinbefore described in relation to the method of delivery in accordance with the first aspect of the invention. The invention will now be described by way of non-limiting, illustrative examples with reference to the accompanying schematic drawings, in which:

Figure 1 is a diagrammatic side elevation of a rotary cement kiln, a portion of the wall of which has been removed for illustrative purposes, the kiln employing a method of delivering material to a unit operable to be fired in accordance with the first aspect of the invention and a method of treating waste in accordance with the second aspect of the invention;

Figure 2 is a diagrammatic side elevation, on a different scale, of one of the articles of encased waste of Figure 1 ; and

Figure 3 is a diagrammatic side elevation, on a different scale, of another article of encased waste employable in a method of delivering material to a unit operable to be fired in accordance with the first aspect of the invention and a method of treating waste in accordance with the second aspect of the invention.

Referring to Figure 1 , a rotary cement kiln is designated generally by reference numeral 10. The kiln 10 employs a method of delivering material to a unit operable to be fired in accordance with the first aspect of the invention and a method of treating waste in accordance with the second aspect of the invention. The kiln 1 0 includes a body 1 1 having a feed end 12 and a discharge end 14. An end cover 15 is located at the feed end 1 2. The body 1 1 of the kiln 10 inclines slightly downwardly (not shown) towards the discharge end 14. Connected to the end cover 15, there is a feeder 16 for feeding limestone, and there is a feed pipe 18 for feeding compressed air that conveys articles of encased material 20 into the kiln 10. Located at the discharge end 14, there is a burner 22 which includes a plurality of pipes, including a central pipe 24 and a plurality of spaced, peripheral pipes 25 (one of which is shown). The pipe 24 is used in this example as a fuel pipe which feeds, into the kiln 1 0, burner fuel for igniting the burner 22. In this example one of the peripheral pipes 25 is used as a feed pipe for feeding compressed air which conveys articles of encased material 20 into the kiln 10. In Figure 1 the articles 20 are shown in block-form. The other peripheral pipes (not shown) are not in use in this example. It will be appreciated that, in an alternative embodiment of the invention, one of the other pipes (i.e. one that is not being used as a feed pipe for feeding compressed air with the encased articles 20) could instead be used as a fuel pipe for feeding the burner fuel to the kiln 1 0. Also located at the discharge end 14, there is an outlet 26 for roasted material (not shown).

Figure 2 shows one of the articles 20 of Figure 1 . The article 20 is employable in a method of delivering material to a unit operable to be fired in accordance with the first aspect of the invention and a method of treating waste in accordance with the second aspect of the invention. The article 20 comprises of a casing in the form of a bottle 28 which is filled with waste grease 32, the bottle 28 having a cross-section which is generally circular in outline. The bottle 28 is of a non- chlorinated, plastics material, in this example, PET. The plastics material is non- chlorinated to reduce environmental pollution. The bottle 28 is sealed with a plug 33 of plastics material. The bottle 28 has a capacity of 500 ml. The bottle 28 is impervious to any leaching out of the grease 32 and thus can be conveniently stored and transported. Air, which is compressed, is admixed with the articles 20, and the compressed air carries the articles 20 to the kiln 10 via the feed pipes 18 and 25, where pyrolysis and combustion take place, thereby to chemically transform the waste. An appropriate pressure of the pressurised air for the mass and shape of the articles 20 is determined by routine experiment, the pressure being selected so as to allow for the articles 20 to be deposited approximately at positions 40 in the kiln 10 where the temperature is such as to allow for efficient combustion of the articles 20 to take place.

Referring to Figure 3, another article of encased waste, designated generally by reference numeral 120, is shown. The article 1 20 is employable in a method of delivering material to a unit operable to be fired in accordance with the first aspect of the invention and a method of treating waste in accordance with the second aspect of the invention. The article 120 has a cross-section which is generally circular in outline. More particularly, the article 120 is generally right circular cylindrical in shape and comprises of a casing, in the form of a close-fitting wrapping 128, which is filled with waste grease 1 32. The wrapping 128 is of a flexible, non-chlorinated, polymeric plastics material, in this example polypropylene. The article 120 is sealed at each of its ends 129 by clamps 130. The wrapping 128 is impervious to any leaching out of the grease 132, and thus the article 1 20 can be conveniently stored and transported.

The invention, as illustrated and described above, allows for flexibility as to where the articles 20, 120 are positioned in the kiln 1 0, and an existing kiln can be retrofitted at a relatively low capital and installation cost with relatively low process disruption and without impairment to the integrity of the body 1 1 of the kiln 10, since the construction of hatches for the articles 20, 120 along the length of the body 1 1 is avoided.

Generally, the encasing of the material means that the material can conveniently be handled as a solid package. The package can be of consistent dimensions, irrespective of what is encased within, and can provide an easily handled product for processing, transport and storage. For example, if the encased material includes carcasses, the encasing avoids the need for separating the liquid oil/fat from the solid material prior to feeding the material into the fired unit. Further, the encasing of the material provides protection from abrasion if an abrasive material is used.