CA2059047A1 - Low wax fireplace log and method of production - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A low wax high wood content fireplace log, in turn, comprising a quantity of loose densified waste wood products, in proportions of, between about 1:5 and 1:10, in volume as compared with the volume of wood products prior to densification, a quantity of hydrocarbon wax binder compounds, which contact the exterior of the loose densified wood products without penetrating them, and in which the quantity of densified wood products and the quantity of wax products are in a proportion of between about 60:40 and 80:20 by weight.

Description

2~9~47 F I E I.D OF THE I NV EN T I ON
The invention relates to a so-called fireplace log of the type macl~ of waste wood chips, and a hydrocarb~n wax binder, and in particular to a fireplace log having a low wax content in comparison to the wood content, and to a method of producing such a low wax high wood content log.

BACKGROUND OF THE I NVENT I O~l Fireplace logs manufactu-ed of waste wood products such as wood chips, saw dust and the like, are very well known and are in wide use. Customarily, these fireplace logs consisting of waste wood chips and saw dust are bound together by hydrocarbon wax, and so-called "pitch" which is in fact an organic resin waste product. The waxes used are typically heavy hydrocarbons, which are themselves waste residues from the processing of petroleum products. Such wax residues are substantially solid at normal temperatures, and will melt at elevated temperatures. Pitch is a waste product from the production of paper, and also acts as an additional binder. Tn the manufacture of such well known fireplace log products, the waste wood chips and saw dust are mixed with the wax and pitch at an elevated temperature, and are then extruded through a tubular die, and allowed to cool. Typically, the logs will have a diameter of somewhere between four and six inches. After cooling they are then wrapped in a suitable paper wrapper . ... ... .. ... . . . . . .. . . .... .... . . . .... ... .. . . . . . .

'~ :
, 2059~7 usually printed with directions for use. Typically the paper wrapper also contains a certain wax content. The directions for use usually include directions to tear the paper and light it with a match. The burning of the paper wrapper will then ignite the log. Once ignited the log will then burn for a considerable length of time providing a steady flame, and a certain limited degree of heat. In this way, persons wishing to use a fireplace may simply purchase these logs, and use them one at a time or more if required to provide at least the appearance of an open haarth fire.
Such fireplace logs are usually employed more for their appearance, and the feeling of general hospitality, than the actual generation of heat. However, they have the great advantage that ~he logs are readily available, can be stored safely indoors, and are available for use more or less instantaneously. In this way, problems encountered using conventional hardwood fuel in open fireplaces are substantially avoided. Hardwood fuels are, in many cases, difficult to start so that they require kindling wood, newspaper, and a certain amount of care before a fire is established. Once ~stablished the fire requires regular attention and the addition of further wood in order to maintain an attractive flaming appearance., The storage of such hardwood products indoors is generally speaking undesirable. Hardwood products frequently contain insects, or insect eggs, and once brought indoors, the 2~9047 insects are liable to escape and eventually infest the home.
For this reason, hardwood fuels are usually left outside and only brought ~n on "as needed" basis. This means that when starting a fire from typical hardwood, it will usually be at the outdoor temperature, which may be extremely cold and must, therefore, be subjected to high heat in order to ignite it. The storing of wood products out of doors also presents a problem. If they become wet, or covered with snow, they cannot be used. Accordingly, they must be stored under cover. This, therefore, creates further problems.
Nonetheless, in spite of all of these problems, a great many persons prefer a genuine hardwood fire, to a fire made of fireplace logs using waste wood products. One of the main reasons for this preference is the fact that typical fireplace logs of the type described above contain a relatively high proportion of wax and pitch. As much as 50 per cent of the weight of a typical fireplace log may be wax and pitch. Consequently, when burning, the typical fireplace log gives off a flame with a blueish tinge, and may also give off an odour which is not characteristic of the burning of hardwood by itself. For these reasons, therefore, in spite of their great convenience, there is some resistance amongst customers tb the actual use of fireplace logs made of waste wood products.
Another factor leading to the disfavour of fireplace ........ ....... ... . . ~ . .. .. ~.. " .. . .... ,. ~ .. .. .. ... .. . .. .....

' `
' , 2~90~7 logs made of wood chips and wax is the fact that persons are increasingly conscious of environmental problems created by certain types of fuel, and in particular petroleum waxes.
The burning of petroleum products in general is regarded as undesirable by many people and consequently persons concerned with the environment are prejudiced against the use of fireplace logs of the type described.
The industry has recognized this problem, and in recent years has developed a proposed standard for fireplace logs, under which logs with a certain minimum wax content may carry a "green" label as being "environmentally friendly".
The industry has more or less arbitrarily concepted a prospective standard of 65 per cent wood and 35 per cent wax and pitch. A fireplace log made up with this content it is hoped, would burn with less odour, and also the flame would not carry the blueish tinge of the typical fireplace log, to the same extent. Thus, it would be, to the customer, more appealing as an environmentally friendly product and, at the same time, less objectionable in that it would not display the typical blueish flame and odour of the conventional fireplace log.
However, attempts to make a conventional fireplace log using wood chips, saw dust, wax and pitch" in the proportions of 65 per cent to 35 per cent, have been unsuccessful. The 35 per cent figure for wax and pitch content simply will not bind the wood chips together and ~- -20~9047 produce an acceptable log. The log will not solidify and hold together when it is extruded and consequently does not function as a log.
A careful study of the problem of the actual content of fireplace logs in the process of manufacture has revealed that the reason for this appears to be that the wood chips and saw dust, during mixing with the heated wax and pitch, actually absorb a considerable quantity of wax and perhaps pitch into the cells of the wood. The wood chips and sawdust are cellular products and are relatively spongy, and the wax being hot and liquid easily penetrates the cells and fills them. Consequently, until enough wax has been added to the waste wood product to fill the cells in the wood chips, and then excess wax is added, there will not be sufficient wax to act as a binder to hold the wood chips together.
Clearly, one solution would be simply to use alternative forms o~ adhesive binders to hold the wood chips together. However, this would not be acceptable, because most adhesives would be more harmful to the environment than hydrocarbon waxes, when burnt at the relatively low temperatures in the typical open hearth domestic fireplace.
Consequently, binders having a greater binding power or adhesion, cannot be used. It is, therefore, clearly desirable to provide a fireplace log having a higher wood content and a lower wax binder content, so as to overcome , .. ;. . . ..... .. ... , ... .... ,.. ,.. ". ..... ... . .... . .................. .. ~.. ~.

' :
' ~ - .

. : . : . ~
. ~ ' , . ' ' : '' .
; . , ~ . , :

2~90~7 the various problems noted above.
BR I EF SUMMARY OF THE I NV EN T I ON
With a view to providing a solution to the foregoing problems, the invention comprises a low wax high wood content fireplace log, in turn, comprising a first quantity of waste wood products, said first quantity of waste wood products being densified, in volume in proportions of, between about 1:5 and 1:10, in volume as compared with the volume of said wood products prior to densification and in which the densified wood products are characterized by an absence of open cell voids, a quantity of heavy hydrocarbon wax binder compounds, which contact the exterior of the densified wood products without substantially penetrating them, and in which the quantity of densified wood products and the quantity of wax products are in a proportion of between about 60:40 and 80:20 by weight.
The invention further comprises such a low wax high wood content fireplace log and wherein the densified wood products comprise at least 50 per cent of wood products having a maximum dimension of between 0.25 and 0.125 of an inch, and a second quantity of approximately 25 per cent of wood products having a dimension between 0.125 and 0.01 of an inch, and the remainder having a dimens~on less than .01 of an inch.
The invention further comprises such a low wax high wood content fireplace log, wherein said wax product are . .

, 20~9~7 characterized by an absence of penetration into said wood products, and extend between said wood products, as a binder, but without penetration of said wood products.
The invention also further comprises a process for the manufacture of a low wax high wood content fireplace log and comprising the steps of forming a mixture of wood products comprising wood chips having an average dimension of between 0.25 and 0.125 of an inch, and wood chips of 0.125 to 0.01 of an inch, and wood dust of 0.01 of an inch or less, compressing said mixture whereby to densify wood products by a factor of between 5:1 and 10:1, breaking up said densified wood products into a loose mixture of densified wood products, adding a quantity of heavy hydrocarbon wax material at an elevated temperature in a liquid phase to said densified loose wood product mixture, and extruding said mixture of densified wood products and wax through an extrusion die, and allowing said wax to cool and harden, thereby forming elongated homogenous masses of densified wood products and wax.
The invention further comprises such a process wherein said wood products are compressed so as to substantially eliminate the cellular structure and voids in said wood products, whereby to prevent the penetrat~on of said wax into said wood products.
The invention further comprises such a process wherein said wood products are in a proportion of between 65 per ... . . . . ..... . . . . . . . .. . . ....... .. .. .. .. ... ... .... . ...... . . .

,' - : -' 20~9~7 cent and 80 per cent by weight, and wherein said wax products are within a proportion of between about 35 per cent and 20 per cent by weight.
The invention further comprises such a process wherein said wax products include heavy hydrocarbon wax material and pitch.
The various features of novelty which characterize the invention are pointed out with more particularity in the claims annexed to and forming a part of this disclosure.
For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the intention.
I N THE DRANINGS
Figure 1 is a perspective illustration of a typical fireplace log, shown with the paper wr`apping partially opened up;
Figure 2 is a greatly enlarged schematic sectional section of a typical prior art fireplace log, and labelled 'Prior Art".
Figure 3 is a greatly enlarged schematic sectional illustration of a low wax fireplace log in accordance with the invention;
Figure 4 is a schematic illustration illustrating the steps in the process of forming a low wax fireplace log, , 20~90~7 Figure 5 is a schematic illustration showing an apparatus suitable for compressing and densifying the wood products prior to manufacture into a low wax fireplace log in accordance with the invention, and, Figure 6 is a schematic illustration showing an apparatus suitable for mixing the separated densified wood products and wax, and extruding the same.
DESCRIPTION OF A SPECIFIC EMBODIMENT
Referring now to Figure 1, a fireplace log is there illustrated comprising a manufactured homogenous log-like block 10, and a paper wrapper 12. The block 10 consists of a mixture of waste wood chips and waste wood products such as saw dust, and heavy hydrocarbon waxes and usually some so-called "pitch" an organic resin waste product. The paper wrapper 12 is fabricated so as to incorporate a certain amount of wax, in most cases, so as to form a flammable fire starter, by ~.Pans of wh.ich the log 10 itself may be ignited.

In this manner, the use of such logs is highly convenient, and a fire of one or more such logs requires substantially no attention once the paper is ignited. The logs usually burn continuously, giving off a flame, so as to provide the hospitable appearance of an open hearth wood fire. However such logs burn with a bluei$h flame and have a characteristic odour.
As best shown in Figure 2, such logs 10 as known and used heretofore, have comprised a plurality of wood chips of _g_ . .

2~9~7 various si~es, and some saw dust, essentially being waste wood products from various types of woodworking machinery and from wood processing factories. Such waste wood products are bound together with a mixture of heavy hydrocarbon waxes (waste products from petroleum oil distillation) and organic resin, a waste products from paper mills. One variety of such organic resins is commercially available under the name "Pamak", (trade mark) from Hercules Incorporated of Wilmington, Del.
In Figure 2, the wood chips and other waste materials are indicated generally as 14, and the wax and "organic resin wastes" mixture is indicated by dots 16. The wax and "organic resin wastes" mixture in Figure 2 is shown as penetrating and permeating through the cells of the wood chips 14, and also filling the spaces between them so as to provide a binder to bind the loose wood chips and saw dust into an homogeneous log. It will thu4 be apparent that there is a considerable proportion of the entire log which consists of wax and "organic resin wastes". Not all of the wax and "organic resin wastes" is acting as a binder. The proportion of the wax and "organic resin wastes" which has penetrated and permeated into the fibres and cells of the wood itself is not acting as a binder, and is essentially unnecessary. However, wood chips and other wood waste products are of such a nature that the cells are open and spongey and are easily penetrated by the hot liquid wax .. ... ... . . ,. ~. ..... ~. . ............. .... .... .. . ......

'. ~ .

- ,.~.: .
:

, 2~90~7 during the conventional manufacturing process used to manufacture such logs. Consequently, such wax once it has penetrated the wood cells and filled them, is not available to act as a binder to hold the wood chips and waste products together. In this respect, such wax and "organic resin wastes" which has penetrated the cells of the wood products is essentially unnecessary to the formation of the log, and is in fact undesirable. Further quantities of wax and "organic resin wastes" must then be added to fill the spaces between the wood chips, and bind them into an homogenous log-like mass.
In accordance with the invention, there is provided a modified form of fireplace log in which the wood chips and wood waste products such as saw dust are first compressed and densified so as to substantially close up and eliminate the cells in the wood after which wax, and some "organic resin wastes", are added as a binder. It will thus be seen that as shown in figure 3, the wood chips indicated generally as 20 are shown to be essentially flattaned, and the saw dust and other finer waste products are essential~ly squeezed flat into flakes similar to the flattened wood chips 20. In this condition, the cells are substantially closed up, and are incapable of taking up any significant guantity of wax. -In this log, made in accordance with the invention, the wax and 'lorganic resin wastes" is indicated generally as 22 - : ~. .

- .

2 0 5 9 ~ ~I r~

and it will be seen that it extends simply between the wood chips and waste products, but does not penetrate or permeate into them to any significant extent.
Conseguently, the log of flgure 3 has a much higher quantity of wood and a lower quantity of wax and "organic resin wastes" than the fireplace log of figure 2. In fact, given suitable densification techniques, it is possible to compress the waste wood chips and saw dust to an extent of between 5:1 and 10:1 by volume. When mixed with hot wax and "organic resin wastes", such densified wood and waste products will thus produce a log which has a much higher wood content and a lower wax and "organic-resin wastes" content, and thus will be more desirable to the consumer, and will also substantially meet the industry standards for a "green"
fireplace log product.
In accordance with the invention it is thus possible to achieve a ~ireplace log as shown in figure 3 having a wood content of at least 65 per cent, with a wax and "organic resin wastes" content of 35 per cent, and in many cases, depending upon the type of waste material and the source of the wood products, it is possible to achieve a better wood to wax ratio than this.
It will of course be appreciated that the wood to wax ratio will vary from time to time depending upon the wood waste material which is supplied to the processing plant ' '' ' ' ' .
"

20~9~
turning it into fireplace logs. Wood waste products which contain a hi~h proportion of saw dust and a lower proportion of chips may require a somewhat higher content o~ wax, and conversely wood products which contain a higher quantity of wood chips, preferably hardwoocl chips, and a lower quantity of saw dust, may require a lower proportion of wax and "organic resin wastes".
The process in accordance with the invention will proceed essentially as illustrated in figure 4 with apparatus as shown schematically in figures and 5 and 6.
As illustrated in the schematic process diagram of figure 4, tha wood waste products are first of all processed by continuous compression in a densifier 30(Fig 5).
Typically a densifier 30 will have a cylinder 32, piston 34, extrusion die 36, and hopper 38. Piston 34 is driven by motor 40.
These densified wood products will usually be produced in an essentially solid form in the form of a continuous solid billet 42 of densified wood. This is because the densification process usually is carried out by forcing the wood products through extrusion die 36. The resulting end product is a continuous generally substantially cylindrical billet of densified wood, in which the wood products are compressed and densified by proportions of between about 5:1 and 10:1.
This billet of densified wood is then passed to the ... . ... . . . .. ... .... . . . . . . . . ....
. . .. .. ., ........... , .. . .. ...... ,. .. , .. .. ....... , .. ... ~ ... . .

' ~.

. . .

2 ~ 7 second stage of the process in which it is broken down in a separator 44 into loose particles of densified wood. This may be done by passing it through a mill, such as a conventional hammer mill(not shown). However, such a hammer mill may result in the breaking up of wood chlps into finer wood particles such as saw dust and other fine wood fragments. This is generally speaking undesirable from the view point of the invention. Fine dust like wood products will tend to take up a greater quantity of wax than will wood chips having dimensions in the region of between and about 0.25 and 0.125 of an inch.
In addition, such fine wood products will tend to break apart during combustion, and may rise up the chimney as wood particles rather than burning, and passing up as products of combustion. This is undesirable since it results in excessive emissions of particulate matter into the atmosphere. Accordingly, whatever techniques are used to separate and break up the solidified billets of densified wood should be preferably such as to minimize the creation -of additional wood dust products.
One technique which is particularly suitable is passing such densified wood billets through a system of rollers, which simply shred and break up the wood billets, but do not grind them up in the same way as a milling davice.
Accordingly, the separator 44 step as illustrated in figure 4 is preferably although not exclusively a roller 2~9~7 crushing device (not shown) of a type well known in the art.
From the separator 44, the broken up loose densified wood particles are then passed to a mixer and extruder 46.
In the mixer the densified wood products from hopper 48 are mixed by an auger 50 with a mixture of hot heavy hydrocarbon waxes, preferably mixed with a proportion of "organic resin wastes", supplied by suitable heated supply means indicated as 52, having any suitable heating means 54.
From the mixing device 46, the mixed wood products together with wax, and "organic resin wastes", if included, : are forced through an extrusion die 56 of a type well knownin the art, thereby producing a continuously extruded log-shaped formation, typically having a dimension of between about 4 and 6 inches in across, and having in same cases a cylindrical shape, and in others an irregular rectangular shape. The waxes in the extruded product rapidly cool and harden, binding the product in an homogeneous product.
The log formations are then cut up into suitable lengths, and wrapped in paper, and packaged ready for sale.
In this way it is possible to produce fireplace logs having a much higher wood content and lower wax content than previously known fireplace logs. The resulting low wax high wood content logs will burn cleaner with a lesser degree of blue flame ancl a lesser degree of undesirable odour than prior art logs and a higher wax content. In addition they . . .. .. . .. . .. .... .. . . . . . . . .. .. . . .. ... . . .. .. .. .. . . .. . . . .. . . . . .. .. . . . . . ... ... ....

'~
:

2~9~4~
will be more environmentally friendly, and will thus have a greater degree of consumer acceptance, than was the case with conventional prior art fireplace logs having a higher wax content since the heavy hydrocarbon wax, as a raw material, is somewhat more costly than waste wood products, the improved low-wax densified wood fireplace logs will have a slightly lower raw material cost, than prior art high wax content logs, which is an addecl benefit.
Typical product data for the heavy hydrocarbon waxes is 1-0 as follows:
Density Boiling ~at 15 c 0.81-0.85 kg/L Range(at 1 atm): 3160C
(wide range) Vapour Pressure N/A
Percent Volatile (at 25 c ) (at 20 c) o%

Vapour Densisty N/A Evaporation ~ate: NjA
(at 20 c~
Solubility in Water Negligible Drop Melting Point: 46-86c Viscosity: 2,8,4,7,4.2,20.3,7.8 Appearance & Odour:

Color less - to yellow solid with ... ... . . . . . . . . ...

, .
.

, , : ' ;' - -' 2~59~

hydrocarbon odour.
(Kinematic) 20,7 c5t (0)100 c (typical respectively) Their chemical formations are complex, and variable, but but will typically include various hydrocarbons in the range of C 20 and up.
Typical product data for t:he oranic resin wastes is as follows:
They are typically obtained by the distillation of crude tall oil.
Viscosity, os 120 8~ ......... ,........................... 425-470 210 F ....................................... 20-30 Ash, % ..................................... 0.3-0.8 Water % ................................... 0.02-0.03 Density,lbs/gal................... 8.4-8.8 API gravity, 60 ................. 9.5-10.6 Specific ~ravity, 26............. 1.01-1.06 Pour Point, ...................... 105-115 BTU/lb ........................ 17,000-18,000 Bulfur, % ........................ 0.15-0.25 Flashpoint, ...................... 470-520 Saponification number ............ 80-120 Aold number - -.-, . ...... .... .. . ... . .. ....... ..... ,...... ,".. ..

.

' ~

2~90~ J

CWTP and TP ....................... 30-50 NTF ............................... 15-25 Iodine number ..................... 90-120 The foregoing is a description of a preferred embodiment of the invention which is given here by way of example only. The invention is not to be taken as limited to any of the specific features as described, but comprehends all such variations therefore as come within the scope of the appended claims.

... .. . . . . . . . . . . . ... . ....... . . . . . . ... . ....

` ~, .
,' '. '~ - ' " : ~ ' ''

Claims (8)

1. A low wax high wood content fireplace log, in turn, comprising;
a first quantity of loosely separated waste wood products, said first quantity of waste wood products being densified, in proportions of between about 1:5 and 1:10, in volume as compared with the volume of said wood products prior to densification;
a second quantity of heavy hydrocarbon wax binder compounds, said wax binder compounds contacting the exterior of said separated densified wood products without substantially penetrating the same;
said first quantity of densified wood products and said second quantity of wax products being in a proportion of between about 60:40 and 80:20 by weight.

2. A low wax high wood content fireplace log as claimed in Claim 1 and wherein said densified wood products comprise at least 50 per cent of wood products having a maximum dimension of between 0.25 and 0.125 of an inch, and a second quantity of approximately 25 per cent of wood products having a dimension between 0.125 and 0.01 of an inch, and the remainder having a dimension less than .01 of an inch.

3. A low wax high wood content fireplace log, as claimed in Claim 1 and wherein said densified wood products are characterized by an absence of open cellular voids, and wherein said wax products are characterized by an absence of penetration into said densified wood products, and extend between said wood products, as a binder, but without adsorbtion by said wood products.

4. A process for the manufacture of a low wax high wood content fireplace log and comprising the steps of;
forming a mixture of wood products comprising wood chips having an average dimension of between 0.25 and 0.125 of an inch, and wood chips of 0.125 to 0.01 of an inch, and wood dust of 0.01 of an inch or less;
compressing said mixture whereby to densify said wood products by a factor of between 5:1 and 10:1;
breaking up said densified wood products into a loose mixture of densified wood products;
adding a quantity of heavy hydrocarbon wax material at an elevated temperature in a liquid phase to said loose densified loose wood product mixture and mixing the same, and, extruding said mixture of loose densified wood products and wax through an extrusion die, and allowing the same to cool and harden, thereby forming elongated homogenous masses of densified wood products and wax.

5. The process as claimed in claim 4 and wherein said wood products are characterized by a spongey cellular structure, easily penetrated by said liquid wax.

6. A process as claimed in Claim 4 wherein said wood products are compressed so as to substantially eliminate said cellular structure in said wood products, whereby to prevent the penetration of said wax into said wood products.

7. A process as claimed in Claim 4 wherein said wood products are in a proportion of between 65 per cent and 80 per cent by weight, and wherein said wax products are within a percentage of between about 35 per cent and 20 per cent by weight.

8. A process as claimed in Claim 4 wherein said wax products include heavy hydrocarbon wax material and "organic resin wastes".