GB2136437A

GB2136437A - Method and equipment for manufacturing paraffin wax-like substances

Info

Publication number: GB2136437A
Application number: GB08406014A
Authority: GB
Inventors: Takashi Kobayashi
Original assignee: RINNE K T I KK
Current assignee: RINNE K T I KK
Priority date: 1983-03-07
Filing date: 1984-03-07
Publication date: 1984-09-19
Also published as: GB8406014D0

Abstract

A method and equipment for manufacturing paraffin wax-like substances are disclosed, wherein polyethylene or other organic solid matter is burnt to initiate pyrolytic reaction and molten product of pyrolysis is further pyrolytically decomposed for formation of paraffin wax-like substances which are useful as various fuels, waxes for lost wax casting process, compounding agents, fillers, extenders, polishes and the like. Combustible gas resulting from the process is recycled and burned to provide thermal energy for continuity of treatment.

Description

SPECIFICATION Method and equipment for manufacturing paraffin wax-like substances Self-burning organic solid matter such as polyolefin resins with their unique properties have been extensively in use as various containers, electric wire covers or sheathes, pipes, packing materials etc. Such various polyolefin products, when they were no longer usable due to e.g. aged deterioration, used to be pelletized for reclaiming as polyolefin or to be disposed of by incineration.

Reclaiming of wastes of polyolefin products, however, requires a lot of energy and expensive equipment, hence the high reclaiming cost, rather higher than the original manufacturing cost, is likely to make such attempt less practical.

Meanwhile, simply incinerating wastes of various polyolefin products is not advisable for it simply means wasting precious resources, being against the advocated recycling of resources, and in addition to the economical loss caused by disposal of resources by incineration, incineration of various polyolefin products possibly causes risk of secondary pollution due to liberation of harmful gas, and thus to date there has been developed no economical and effective method or equipment for reclaiming organic solid matter such as the polyolefins polyethylene, polypropylene and polystyrene.

The present invention provides a method and equipment for manufacturing cheap yet useful paraffin wax-like substances from wastes of organic solid matter such as polyethylene.

The present invention also provides a method of manufacturing paraffin wax-like solid fuels, and paraffin wax-like powder fuels from organic solid matter such as polyethylene.

The present invention also provides a method of manufacturing organic fuels such as naphtha from organic solid matter such as polyethylene.

Furthermore, the present invention provides a method of feeding as fuel to a boiler a paraffin wax-like melt manufactured from organic solid matter such as polyethylene.

Accordingiy, the invention provides a method of manufacturing paraffin wax-like substances from organic solid matter, wherein self-burning organic solid matter is caused to burn inside a combustion basket and the liberated heat of combustion is used for heating and melting further organic solid matter as well as for initiating a pyrolytic reaction, molten products are introduced into a pyrolysisenhancing basket for enhancement of the pyrolytic reaction, combustible gas resulting from vaporization of part of the molten products produced during the pyrolytic reaction is recycled to said combustion basket and burned to provide thermal energy for continued combustion and the melt having passed through said pyrolysisenhancing basket is collected as paraffin wax-like substances in a melt receiving tank, and optionally the paraffin wax-like substances are subsequently further processed. The organic solid matter may be a polyolefin, e.g. polyethylene, polypropylene, polystyrene. The self-burning matter is preferably a high-crosslinked polyethylene resin, but it may be other combustible plastics material, or cellulosic matter such as wood, paper and the like.

The organic solid matter from which the paraffin wax-like substances are obtained by pyrolysis may be a polyolefin as above or it may be organic matter which does not sustain combustion, e.g. a polyolefin such as non-crosslinked polyethylene, low-crosslinked polyethylene and the like.

Referring now to the accompanying drawings, preferred embodiments of the method and equipment for manufacturing paraffin wax-like substances of the present invention are described below in detail.

FIGURE 1 is a view in vertical section showing an embodiment of equipment of the present invention for manufacturing paraffin wax-like substances.

FIGURE 2 is a general schematic view showing a fuel feeding system incorporating the above equipment.

The manufacturing equipment has a fire-proof housing forming its outer wall structure. The housing 1 has extending inward therefrom a plurality of supporting members 2 whereby a tank for receiving paraffin wax-like melt 3 is suspended inwardly of the housing 1. This paraffin wax-like melt receiving tank 3 is fire-proof, and there are provided outlets 4, 5, 6 for paraffin wax-like melt.

In the periphery of the tank 3 there are provided adjustable air inlet ports 7 for regulating the amount of oxygen inside the tank 3.

On top of the open upper end of the tank 3 is mounted a fire-proof combustion basket 8 with its upper as well as its lower end open, its lower open end 8a is set inside the upper open end of the tank 3. Inside the basket 8 there is disposed iaterally and partition-like a material pan 10 with a multiplicity of holes 9 for passing paraffin wax-like melt and the peripheral side wall of the basket 8 has numerous air inlet holes 11 above the material pan 10. The material pan is convex in shape with its periphery spaced apart from the inner peripheral wall of said combustion basket.

There is suspended from the lower open end of the basket 8 a fire-proof pyrolysis-enhancing basket 1 2 with its upper end open, which has a multiplicity of holes 1 3 in its bottom and meshlike holes 14 in its peripheral side wall, and the basket 1 2 as a whole is mounted in the tank 3.

The aforesaid paraffin wax-like melt receiving tank 3, combustion basket 8 and pyrolysis enhancing basket 1 2 constitute a furnace means.

The housing 1 is provided with a material feeding chute 1 5 with its inner end above the open upper end of the combustion basket 8. The housing 1 has provided in its peripheral wall an air inlet window 1 6 and in its top an exhaust port 17.

The method of reclaiming paraffin wax-like substances from solid polyethylene by the use of the above-described equipment is as follows.

Non-crosslinked or low-crosslinked polyethylene has the so-called self-extinguishing property in which, when it is ignited, the point ignited and its vicinity are only locally molten and the melt covers the adjacent unignited areas to prevent spread of flames. Hence, supply of thermal energy from outside is required for burning or pyrolytically decomposing such kinds of polyethylene.

In contrast thereto, high-crosslinked polyethylene has self-burning property, burning unaided once it has been ignited, the combustion temperature being approximately 9000 C or even higher.

Therefore, high-crosslinked polyethylene with its self-burning capability (polyethylene for combustion) may be used as means of developing a temperature required for conversion of polyethylene into paraffin wax-like products, and high-crosslinked polyethylene with its self-burning capability as well as non-crosslinked or lowcrosslinked polyethylene or mixtures thereof may be used as polyethylene for pyrolysis to paraffin wax-like products.

As charge material A may be used, for example, a mixture of waste of crosslinked polyethylene as polyethylene for pyrolysis with polyethylene for combustion, and the required amount of the material A is let into the combustion basket 8 through the material feeding chute 1 5. More particularly, both polyethylene for combustion and polyethylene for pyrolysis may be provided by the polyethylene sheath of an electric cable without removal of accessories. The charge material A may as well be polypropylene, polystyrene or any other organic solid matter.

When, the polyethylene for combustion of the charge material A in the combustion basket 8 is ignited the resulting thermal energy causes sustained combustion of the polyethylene for pyrolysis, at the same time giving rise to pyroiytic reaction.

A few minutes after the start of combustion, paraffin wax-like melt B resulting from melting of the material A drips down through the multiplicity of holes 9 in the material pan 10 and the gap between the material pan 10 and the peripheral side wall of the combustion basket 8. The melt is separated from the incombustible accessories and temporarily dwells in the pyrolysis-enhancing basket 12 located under the combustion basket 8.

The paraffin wax-like melt B having dripped into the pyrolysis-enhancing basket 1 2 passes after a while through the holes 13 in the bottom of the basket to further drip into the paraffin wax-like melt receiving tank 3.

The paraffin wax-like melt B or C temporarily dwelling in the tank 3 or in the pyrolysisenhancing basket 12 combines with oxygen of air therein. Since the interior of the tank 3 is constantly in the state of oxygen shortage due to the combustion or pyrolytic reaction therein, part of the melt is vaporized in the course of pyrolytic reaction with liberation of combustible gas G. The gas G liberated in the tank 3 rises therein to subsequently flow into the pyrolysis-enhancing basket 1 2 through the mesh-like holes 14, while the gas liberated in the pyrolysis-enhancing basket 12 rises therein and past the holes 9 in the material pan 10 into the combustion basket 8.

Inside the combustion basket 8 the combustible gas G rising from its bottom and the thermal energy liberated through self-combustion of the polyethylene in the air let in through the inlet holes 11 interact for synergistic enhancement of the primary combustion and pyrolytic reaction. Since the combustible gas G is burnt instantaneously as it combines with the oxygen in the air let in through the air inlet holes 11 of the basket, a flame is generated at each air inlet hole 1 as if the peripheral side wall of the combustion basket 8 were provided with burner means for effective heating of the interior of the combustion basket 8, and a large rising mass of flames F is formed in the basket 8.Thus, since flames are generated along the peripheral side wall of the combustion basket 8, there is no risk of gas leakage out through the air inlet holes 11.

Since an extremely large amount of thermal energy for combustion is imparted to the material A fed into the combustion basket 8, the combustion efficiency for the material A is extremely high and continued combustion is maintained without supply from outside of additional thermal energy.

The paraffin wax-like melt B in the interior of the pyrolysis-enhancing basket 1 2 combines with the oxygen contained in the small amount of air inside the tank 3 for enhancement of the progress of the pyrolytic reaction.

Since oxygen thus becomes short and negative pressure prevails in the tank 3 and the pyrolysis enhancing basket 12, dripping of the paraffin waxlike melt in the combustion basket 8 is enhanced, while the paraffin wax-like melt in the tank 3 is boiling at a relatively low temperature and liberates a lot of combustible gas G in a vaporization inducing atmosphere, and thus pyrolytic reaction of the paraffin wax-like melt B is further enhanced.

An amount of air is let in through adjustable air inlet ports 7 so that a state of oxygen shortage in the tank 3 is maintained, the melt C in the tank 3 is constantly kept at a high temperature and also an atmosphere for easy vaporization of the melt is maintained.

The boiling point of the paraffin wax-like melt, which is approximately 4600 C in the normal atmosphere, is approximately 200--2300 C under the negative pressure in the tank 3, hence the melt C in the tank 3 is constantly in the state of lowtemperature boiling.

The paraffin wax-like substances thus obtained have a low flash point so that they are easily ignitable by match flame and excellent in combustibility and combustion sustaining performance, and were found in tests to have calorific values higher than 1 1,240 cal/g. They are, therefore, useful, as they are, as liquid fuels and also as solid fuels made by allowing the liquid fuels to cool to set, also being useful in many other ways e.g as waxes for lost wax casting process, compounding agents, fillers extenders and polishes.

Described below is the result of an experiment in which waste polyethylene electric cable sheath was used as polyethylene for pyrolysis and also as polyethylene for combustion and paraffin wax-like products C were made therefrom by the use of the equipment of the present invention. The waste polyethylene sheath used as material A was complete with incombustible accessories.

When approximately 10 kg of the material A was charged in the combustion basket 8 and ignited, the material A started burning and in approximately 9 minutes after the start of combustion the greater part of the material was pyrolytically decomposed and the liquefied paraffin wax-like melt was seen dripping, and after enhancement of the pyrolytic reaction in the pyrolysis-enhancing basket 12, the paraffin waxlike melt C having dropped into the tank 3 to collect on its bottom was sampled through the outlet 4, 5 or 6 of the tank 3 and was cooled to set. Solid samples of paraffin wax-like substances were obtained. The volumetric shrinkage rate of this substance as it solidified was approximately 2%, its specific gravity was 0.8 and its yield was approximately 85%.

EXAMPLE 1 The thoroughly pyrolytically decomposed paraffin wax-like product C in molten form is taken out through the outlet 4, 5 or 6 of the tank 3, mixed with a combustible substance and then cooled (or allowed to cool) to set to provide a paraffin wax-like solid fuel.

The combustible substance to be mixed with the molten product C may be sawdust, various carbon preparations, imperfectly burnt ashes of organic matter or dried sludge discharged from paper making process or the like, but the present invention has nothing to do with the particular material used for the purpose or the quantity mixed thereof. Through mixing of such combustible substance improvement of the combustibility, ignitability and combustion sustaining performance as well as increase of the calorific value of the solid fuel could be easily accomplished.

EXAMPLE 2 The paraffin wax-like melt C taken out of the tank 3 was cooled (or allowed to cool) to set and then pulverized to provide a paraffin wax-like powder fuel. The present invention has nothing to do with the particular method of pulverizing the solid, this being well feasible by the use of a conventional crusher or the like.

EXAMPLE 3 The paraffin wax-like product C in molten form is separated from suspended carbon particles by electrostatic induction or the like after it is taken out through the outlet 4, 5 or 6 of the tank 3 or while it is in the tank 3. The paraffin wax-like melt thus refined provided an organic fuel high in calorific value (approximately 12,000 cal/g), and is to be classified as heavy oil or crude gasoline (naphtha) according to the degree of elimination of suspended carbon particles. Among the possible uses are as fuels for ceramic industry, metal refining, steel making as well as for internal combustion engines for those classified as heavy oil and as fuels for various engines for those classified as gasoline.

As shown in Fig. 2, the abovementioned manufacturing equipment for paraffin wax-like substances is used as equipment for fuel manufacture, the tank 3 of the fuel manufacturing equipment 19 and a combustion chamber 21 of a boiler are arranged to communicate and a fuel metering pumping means 20 is provided in a fuel feeding path between the tank 3 and the combustion chamber 21 so that the paraffin waxlike melt C pyrolytically decomposed in the tank 3 is fed as fuel to the combustion chamber 21 of the boiler 1 8 for the boiler to be supplied with the required thermal energy for combustion. The above-mentioned boiler 1 8 may be a cylindrical boiler, water-tube boiler or any other special type of boiler. The paraffin wax-like melt C may be fed at a constant rate continuously by the metering pump means 20.

Thus, according to the method of manufacturing paraffin wax-like substances of the present invention, substances highly useful in many ways e.g. as heat source or power source fuels as well as waxes for lost wax casting process, compounding agents, fillers, extenders or polishes can be manufactured from wastes of various polyethylene products, polystyrene products or other organic solid matter. The invention thus provides for successful recycling of resources such as polyethylene.

Moreover, since, according to the present invention, the properties of polyethylene or the like having a self-burning feature are utilized so that the heat of combustion is used to heat up and melt organic solid matter and to initiate pyrolytic reaction, and further additional thermal energy is generated by combustion in the combustion basket through combustion with oxygen of combustible gas liberated during enhancement of pyrolytic reaction after melting and this thermal energy is used for heating the material in the combustion basket, no supply from outside of thermal energy is required for combustion and pyrolytic processing of the charge material.

Moreover the productivity of paraffin wax-like substances is good and its economical merit is quite remarkable as well as its energy-saving feature, especially when the possibility of recycling organic solid matter is taken into account.

Especially, the solid paraffin wax-like substances obtained by mixing the paraffin waxlike melt after enhancement of pyrolytic decomposition with combustible substances and subsequent cooling for setting are markedly improved in combustibility, ignitability and combustion sustaining performance as solid fuels with an additional feature of having their calorific values easily and substantially increased thereby.

When the paraffin wax-like melt after enhancement of pyrolytic decomposition is cooled to set and subsequently pulverized for use as a powder fuel, it is highly improved in ignitability and combustibility due to the oxygen of air present among the fuel particles, being thus useful as heat source for various combustion apparatuses and having further advantages with regard to conveyability, transportability and feedability.

Further, paraffin wax-like substances refined by eliminating suspended carbon particles by electrostatic induction or the like provide useful organic fuels, which can be classified as heavy oil or crude gasoline according to the degree of elimination of carbon particles suspended in paraffin wax-like melt.

When a low cost paraffin wax-like substance is fed to the combustion chamber of a boiler as it is manufactured in the molten form, the conventional fuel for boiler operation such as coal (including powdered coal), heavy oil and gas can be totally dispensed with and the paraffin wax-like molten fuel alone is capable of supplying the thermal energy required for boiler operation.

Further, since the manufacturing equipment as a whole is simple in construction and easy to build, and it is so planned that the heat from combustion of polyethylene or the like itself is utilized, there is no risk of thermal damage to any of its constituent components and there are less causes for trouble, the manufacturing equipment being thus highly durable.

Since the flames formed at individual air inlet holes of the combustion basket extend toward the interior of the basket and are focussed on the material, any risk of leakage of the combustible gas through the air inlet holes in the peripheral side wall of the combustion basket is precluded thereby further enhancing the combustion efficiency of the material and, moreover, since the temperature in the combustion basket itself is not caused to be too high, there is no risk of thermal damage or thermal deformation thereof, this being beneficial for the durability of the equipment.

In the illustrated embodiment a unit of the pyrolysis-enhancing basket 1 2 is provided right under the combustion basket 8, but optionally a plurality of pyrolysis-enhancing baskets may be arranged further thereunder for further enhancement of the pyrolytic reaction.

Although the combustion and pyrolytic decomposition of organic solid matter in the above-described equipment is described as being carried out in the atmosphere, it is also possible to perform it in a closed container. It is further possible to conduct combustion and pyrolytic decomposition in a separate combustion furnace and pyrolytic furnace. The heat of combustion may be introduced into the pyrolytic furnace for burning and pyrolytic decomposition of organic material.

Claims

1. A method of manufacturing paraffin wax-iike substances from organic solid matter, wherein self-burning organic solid matter is caused to burn inside a combustion basket and the liberated heat of combustion is used for heating and melting further organic solid matter as well as for initiating a pyrolytic reaction, molten products are introduced into a pyrolysis-enhancing basket for enhancement of the pyrolytic reaction, combustible gas resulting from vaporization of part of the molten products produced during the pyrolytic reaction is recycled to said combustion basket and burned to provide thermal energy for continued combustion and the melt having passed through said pyrolysis-enhancing basket is collected as paraffin wax-like substances in a melt receiving tank, and optionally the paraffin wax-like substances are subsequently further processed.

2. A method of manufacturing paraffin wax-like substances as recited in claim 1, wherein polyethylene is used as said organic solid matter.

3. A method of manufacturing paraffin wax-like substances as recited in claim 1, wherein polypropylene is used as said organic solid matter.

4. A method of manufacturing paraffin wax-like substances as recited in claim 1, wherein polystyrene is used as said organic solid matter.

5. A method of manufacturing paraffin wax-like substances as recited in any one of claims 1 to 4, wherein in the subsequent processing one or more combustible substances are mixed in with said melt after enhancement of pyrolysis and said mixture is subsequently cooled to set.

6. A method of manufacturing paraffin wax-like substances as recited in claim 5, wherein carbon preparations are used as said combustible substances.

7. A method of manufacturing paraffin wax-like substances as recited in claim 5, wherein imperfectly burnt ashes of organic matter are used as said combustible substances.

8. A method of manufacturing paraffin wax-like substances as recited in claim 5, wherein dried sludges from paper manufacturing process are used as said combustible substances.

9. A method of manufacturing paraffin wax-like substances as recited in any one of claims 1 to 4, wherein after cooling to set said melt after enhancement of pyrolysis said paraffin wax-like substances are pulverised to powder form.

10. A method of manufacturing paraffin waxlike substances as recited in any one of claims 1 to 4, wherein said melt is refined to provide organic fuels by elimination of suspended carbon particles.

11. A method of manufacturing paraffin waxlike substances as recited in claim 10, wherein elimination of said carbon particles suspended in said melt is done by electrostatic induction.

12. A method of manufacturing paraffin waxlike substances as recited in any one of claims 1 to 4, wherein said melt, after enhancement of pyrolysis, is pumped to the combustion chamber of a boiler at a constant rate.

1 3. Equipment for manufacture of paraffin waxlike substances, wherein a combustion basket with its top and bottom open and with a perforated material pan laterally extending within its inner peripheral wall is mounted on the open top of a melt receiving tank with adjustable air inlet ports in its peripheral wall, air inlet holes are provided in the peripheral wall of said combustion basket and one or more pyrolysis-enhancing baskets each with its top open and its peripheral side wall perforated is/are arranged inside said tank.

14. Equipment for manufacture of paraffin waxlike substances as recited in claim 13, wherein said material pan is convex in shape with its periphery spaced apart from the inner peripheral wall of said combustion basket.

1 5. Equipment for manufacture of paraffin waxlike substances as recited in claim 13, wherein at least one similar basket is connected to the bottom of said pyrolysis-enhancing basket.

1 6. Equipment for manufacture of paraffin waxlike substances as recited in any one of claims 1 3 to 15, wherein said paraffin wax-like melt receiving tank is connected to the combustion chamber of a boiler and a fuel feeding path is provided therebetween with fuel metering pump means.

1 7. A method of manufacturing paraffin waxlike substances substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

1 8. Equipment for manufacture of paraffin waxlike substances substantially as hereinbefore described with reference to Figures 1 and 2 of the drawings.

Superseded claim 1.

1. A method of manufacturing paraffin wax-like substances from organic solid matter, wherein self-burning organic solid matter is caused to burn inside a combustion basket and the liberated heat of combustion is used for heating and melting organic solid matter as well as for initiating a pyrolytic reaction, molten products are introduced into a pyrolysis-enhancing basket for enhancement of the pyrolytic reaction, combustible gas resulting from vaporization of part of the molten products produced during the pyrolytic reaction is recycled to said combustion basket and burned to provide thermal energy for continued combustion and the melt having passed through said pyrolysis-enhancing basket is collected as paraffin wax-like substances in a melt receiving tank, and optionally the paraffin wax-like substances are subsequently further processed.