IE51262B1 - Process for the production of a dust from coniferous substances - Google Patents

Abstract

The invention describes a process for recovery, treatment and upgrading of conifers, particularly their substance carriers comprising root stocks, roots, barks as well as branches and twigs overgrown with needle-like or scaly leaves and seed-capsules to provide energy sources, particularly fuels, as well as raw materials for hydrotherapy and the soil. The substance carriers are ground in mills to reduce them to fine particle size. The resulting dusts may be used as such as fuels or to produce industrial gases. Further, a pasty mixture of the dusts with water or heavy oil can be used to produce fuels or it may be processed with hydrogen in the presence of catalysts into gasoline, oils and/or gases. The ground material also may be used as slurry or mud used for therapeutic purposes or medicinal bath water by adding metered water. Finally the ground material may be mixed with peat to be used as energy source or as manure for the soil.

Description

The present invention relates to a process for the production of a dust from normally discarded material having little or no wood content obtained from coniferous plants.

The coniferous plants may be in the form of shrubs or bushes and the parts thereof which are used in the present invention are the roots, root stocks, bark, twigs which are overgrown with needles or scales and seed capsules or mixtures thereof.

The production of new materials which can, inter alia, be used as fuels is extremely important and continuous efforts are being made to utilise, hitherto untapped sources of energy This is because the main sources of energy used hitherto are fossil fuels such as coal, oil and gas and nuclear energy.

The available supplies of fossil fuels are already running low and such fuels are non-regenerative. It is also generally accepted that the enormous worldwide use of fossil fuels adversely affects the environment and such use has already started to affect everyday life styles. Nuclear energy has many advantages over fossil fuels but is inevitably dangerous because, even with the most careful planning and control of nuclear power plants the avoidance of radiation hazards cannot be totally guaranteed. A further problem is the disposal and final storage of the by-products of nuclear fuels, that is to say the radioactive waste.

The present invention seeks to provide a dust from materials taken from regenerative plants. Thus, conifers comprise parts which contain little or no wood, such as those parts identified hereinbefore. The present invention therefore seeks to utilise such parts as starting material. Such parts of the plant contain photosynthesis products and it will be appreciated that photosynthesis is the most significant biochemical process and is theoretically, the greatest known - 3 energy generating source. Portions of the plants which are essentially free of wood have a chemical composition comprising chiefly carbon, hydrogen, oxygen and nitrogen in the form of tannin, cellulose, hemicellulose, lignin, resin, waxes and essential oils.

According to the present invention, there is provided a process for the production of a dust from normally discarded, scantily-wooded, coniferous material selected from twigs, needles, scaly leaves, seed capsules, root stocks, thin roots and mixtures thereof, said process comprising comminuting said material to a coarse product having a particle si2e of about 10 mm, further comminuting the coarse product to produce a product having a median particle size of 0.5 to 1.0mm, the dust produced being utilisable as a fuel or then being treated to form briquettes, industrial gases or therapeutic agents or, in admixture with peat, fertilisers.

In one embodiment, the process comprises the additional steps of treating the product having a median particle size of 0.5 to 1.0 mm to remove adhering fibrils, the treated particles then being admixed with Water in an amount sufficient to raise the water content thereof to substantially 70% by weight, the aqueous mixture subsequently being subjected to a still further comminution step to produce a wet dust having a mean particle size of 0.001 to 0.5 mm. The dust then obtained can, if desired, be dried during the comminution treatment utilising waste heat from elsewhere and the final product can be used as a fuel in a dust-like form.

The intermediate material having a median grain size of from 0.5 to 1 mm can be screened or sifted to remove the adhering fibrils. By adding water, the moisture content of the product may be raised to 70% by weight and the wet material is then ground and pulverised in mills until it has a median grain size of from 0.001 to 0.5 mm. The resultant product is a kneadable paste which can be formed and compacted in extruders without the need of applying excess pressure thereto. - 4 The extruded product can then be dried and shrunk in a hot air stream to reduce the moisture content to 8 to 10% by weight the product then being in the form of hard moulded pieces. The dust having a median grain size of from 0.001 to 0.5 mm can be dried to a moisture content of less than this to facilitate further processing.

Alternatively, the dust may be used as a source material for the production of industrial gases in which case it is gasified in the presence of a gasifying agent at a temperature of from 900°C to 1200°C.

The dust, having a median grain size of not more than 0.002 mm and 5% moisture content by weight can, if desired, be mixed with heavy oil. The resulting product is then reacted with hydrogen in the presence of catalysts and conver15 ted into fuel, gasoline, oils and/or gases.

Further alternatively, the dust is treated to form a fertiliser, the treatment comprising processing admixing the dust with partially dewatered peat having a moisture content of from 70 to 75%, by weight the partially dewatered peat being added in an amount sufficient to impart a moisture content of from 35 to 65% by weight to the mixture.

Still further alternatively, the dust is treated to form a fertiliser, the treatment comprising admixing the dust with raw peat having a moisture content of substantially 90% by weight, the raw peat being added to an amount sufficient to impart a moisture content of from 50 to 75% by weight to the mixture.

Finally, it is possible to add warm or hot water to the ground material to prepare a slurry which may be utilised as such or may be filtered to form an aromatic extract, both of which are utilisable as therapeutic agents.

The process of the invention is a promising way to utilise natural, continuously regenerative energy sources, that is to say cultivatable plants. - 5 The treatment of the starting material is uncomplicated and does not require any undue expenditure on apparatuses for carrying out the process. Accordingly, an economically viable process is attained. The basic materials are virtually inexhaustable in that conifer plantations, once set-up, can be renewed continuously, over a period of time, in a cyclic manner. It is admitted that there are large differences in calorific content between the energy generating sources provided by the process of the present invention and conventional energy sources, such as mineral oil, coal, gas or even uranium. However, the advantages of a non-exhaustible, generally economic process which is not ecologically harmful, the use of which is substantially free from problems and risks,compensates for these disadvantages.

Furthermore, a comparison of conventional coal-fired power stations with power stations utilising the coniferous dust produced by the process of the present invention proves favourable. Particularly advantageous is the utilisation of coniferous dust in turbo-power stations, e.g. gas-turbines with an open cycle utilising a hot gas mixture produced in a combustion chamber by the interaction of hot compressed air and coniferous dust. Such gas-turbines have a very high efficiency. The adaptation of the efficiency and rating of such gas-turbines to load changes is performed by simple regulation and control of the pressure. The waste heat obtained from a reflux condenser is fed directly to the specific distribution network and without affecting the efficiency and output of the electric and output of the electric energy generation. In such a way, the overall efficiency is considerably Increased. For distant heating power stations it is possible to extend the radius of the area of application to 2 to 3 km. In addition, it is possible to utilise the waste heat in other ways by connecting other suitable devices, such as waste heat vessels and the like, thereto. Accordingly, it is evident that coniferous dust - 6 has a worldwise potential as a novel energy source. Furthermore, the burning of coniferous dust is not ecologically harmful and is environmentally compatible because the amount of sulphur dioxide which escapes into the atmosphere is very small or may even be zero.

For economic reasons it is advisable to establish power or generating stations either at the center or at the borders of coniferous plantations. The generated power supply will therefore be relatively inexpensive to produce because of the low cost of the raw materials and the minimal cost of transporting such materials.

Gas-turbine stations can be constructed and operated to provide 2 to 150 MW of electric energy. The possibility of positioning such stations in the locations where the raw materials are available offers advantages over conventional coal-fired power stations of much higher power efficiency. Thus, small electrical energy generating stations can be installed in very small plantations and farms which are far from an overland supply network and from conventional power 2o stations. Moreover, an electrical supply can be made available for residential and industrial districts being built.

The treatment of the coniferous material to produce a fine-grained dust is carried out in mills, preferably in socalled pulverizers. The type of mill used depends upon the structure of the material to be treated. The following steps are, however, generally effected:1. The granular material is beaten and ground to form a bulk for further utilization in dust firing in order to increase the speed of combustion. 2. The material to be ground is dried whilst it passes through the mill, waste heat being used to effect the drying.

During the crushing and pulverizing of the material dried to a moisture content between 20 to 25% by weight most of the spent kinetic energy is converted into heat, whereby - 7 the material being ground is strongly heated. It may, therefore, lose 10% or more by weight of its moisture content. That means that the fuel used in the combustion process has a moisture content of 10 to 15% by weight.

The ground or pulverized materials can be used as fuels but they also may serve as raw materials for processes of gasification, earburetion, hydrogenation and briquetting.

In the case of wet treatment of the material for preparing pastes or slurries, heating favourably affects the following thermic drying. The production of pastes is essential for the preparation of coke.

The process techniques utilised in preferred embodiments of the present invention may be separated into the steps of grinding, screening or sifting, forming, drying and filtering the material.

All of the apparatus and machinery used for carrying out the process of the present invention are well known. However, their utilisation in the process of the present invention is novel.

The following Examples illustrate the process of the present invention: Example 1 The coniferous material is ground in a conventional mill and reduced to an average grain size of 1 to 2 mm, the moisture content of the material then being increased to about 70% by weight by adding a metered amount of water. In this condition the material is placed into ball or colloid mills - or similar equipment - wherein it is comminuted down to form pastes having particle sizes of the order of 1 micron.

Such pulverization, resulting in an increase in surface area, is followed by compacting which results in a decrease in the surface area. During the pulverization step, the temperature of the material is raised considerably and, due to its resin content, becomes mouldable to a paste which can be extruded without the need of high pressure to form moulded 262 - 8 pieces of different sizes and shapes. The moulded pieces are dried in a stream of hot air to reduce the water content to 8 to 10% by weight. Thereby the mouldings shrink in a proportion of about 3 : 1 by weight. In the drying and shrinking process, the mouldings behave like true colloids, that is to say, their edges remain substantially unchanged whilst their surfaces collapse into a concave shape.

The dried mouldings are hard, crack-free and abrasionresistant. They are subjected to a carbonization at low temperature and to a cooking and degasification process at temperatures from 725° to 1200°C. From the degasification process, solid residues are obtained consisting of high-grade moulded cokes, the purity of which regarding the sulphur, phosphorous and ash contents is superior to other coke types.

The thermal value of the obtained cokes is about 30,000 BTO/kg (7,500 kcal/kg) and the yield is about 30% by weight. The gases produced in the degasification process are also pure with respect to their sulphur, phosphorous and ash contents.

The gases may be utilised as valuable raw materials either directly or may be fractionated to form raw materials in the power, metallurgical and chemical industries. In other words, the raw gas can be burned as an energy source in power stations connected in parallel with the coking plants or they can be fractionated to produce oils and gasolines.

Example 2 The coniferous material is initially pulverised, as is stated in Example 1. In order to obtain typically different dusts, it is proposed according to one embodiment of the invention to utilise the first, second and third grinding steps but in which the dusts are sifted between the second and third steps in order to remove the fibrils. In this way it is ensured that the dusts, which have been wetted with water to increase their moisture content to about 70% by weight can be processed into an homogenous paste or slurry so that the ensuing thermal drying is uniform. Fibrils present in the mass would cause small cavities which adversely affect the density and hardness - 9 of the moulded pieces. Finally the mouldings are treated as in Example 1.

Exanple 3 The dusts produced in either Example 1 or Example 2 are wetted with a metered amount of water to give them a moisture content of about 35% by weight. A viscous paste is then produced which then is compressed to form briquettes in a conventional press. The moisture content is thereby reduced to 20 to 25% by weight. In this condition, the briquettes are formed into desired shapes and sizes and are further treated as described in Example 1.

Exanple 4 The dusts produced in either Example 1 or Example 2, which have a moisture content of 10 to 15% by weight are formed, without the addition of further water into briquettes of the desired shape and size and are then further treated as described in Example 1.

Exanple 5 The dusts produced in Example 1 or Exanple 2 are used as pure dust-energy-sources for direct combustion in thermal power stations.

Exanple 6 The dusts produced in Example 1 or Example 2 are completely gasified using conventional gasification means such as air, steam, carbon dioxide, technical grade oxygen or hydrogen at a temperature of between 900° and 1200°C to produce industrial gases.

Example 7 The dusts produced in Example 1 or Example 2 can be used in conventional hydrogenation processes in which they replace lignite and/or pit-coal.

In the hydrogenation process of Bergius/Pier, for instance, the lignite is mixed with heavy oil and is converted into fuels, oils and gases by reaction with hydrogen in the presence of catalysts. - 10 Such hydrogenation process is carried out in two phases:1. ) a sump or liquid phase, 2. ) a gas phase.

This process was carried out using a coniferous material dust prepared by the process of the present invention in place of the lignite or pit coal. A slurry of such dust with motor oil was made as follows:The dust, having a particle size of about 1 micron and a density of 440 g/1 was mixed with 5% HgO by weight and with motor oil, having a density of 800 g/1. litres dust = 2,200 g. x 5,kcal = 11,000 kcal (44,000 BTD) litre oil = 800 g. x 10 kcal = 8000 kcal (32,000 BTD) Thus, a 6 litre mass, weighing 3kg had a calorific value of 19,000 kcal (76,000 BTU). The mass was introduced into a centrifugal mill and treated to form a homogenous system. Thereby, the temperature of the mixture increased considerably within about 5 minutes accompanied by a simultaneous, noticeable, shrinking. The mixture cooled upon removal from the centrifugal mill. The finely grained dust particles were completely oiled up so that a uniform mixture was obtained with no detectable interfaces between the com25 ponents. The consistency of the slurry was sticky, that is to say, viscous.

The following values were measured. The initial 6 litre (3 kg) mass shrunk to 2.66 litres so that a 0.887 litre mass is equivalent to 1 kg and yield 6.333 kcal.

Thus values for the slurry prove the capability of the dusts produced by the process of the present invention being used in high-pressure gasoline recovery processes.

The dusts produced in Example 1 or Exanple 2 are suitable for use as hydrotherapy treatment agents. The - 11 treatment of the dusts for such use is different. it is possible to treat the dusts either by adding a selected dosage of warm water thereto to form a slurry which may be used as such or may be filtered to prepare an aromatic, brownish therapeutic bath-water free from suspended particles.

The processes described hereinbefore can be carried out utilising older coniferous plants. The timber industry offers an excellent source of coniferous materials. However, the conventional prior art utilization of such materials is wasteful because 60 to 70% by weight of each cut tree have hitherto been considered useless, even though such portions form the major portion of the tree. This is where the process of the invention can be used, because the waste from known wood-cutting operations can be treated and processed as described hereinbefore.

The costs of carrying out the process of the present invention are minimal compared with the costs of conventional techniques. The operation of the machines necessary for carrying out the present process is relatively simple and there is little danger of environmental contamination. The programmed set-up and cultivation of coniferous plantations make it possible to replace, or at least considerably relieve, the pressure on present centralized power generating plants which are either located near to their energy sources or need to be maintained and supplied with their energy sources utilising long distance, and hence expensive, transportation. The construction and operation of power stations which utilise the coniferous dust produced by the process of the present invention can be managed and controlled in decentralized systems, either regionally or in local areas. The present, large power stations may be replaced by smaller secondary systems. This means that the regional and local requirements of domestic and industrial users can be satisfied in a better and more reliable manner than hitherto.

The coniferous materials can also be treated and up51262 - 12 graded to form humus which may be used either by itself or mixed with manure and which can be used to improve and cultivate the soil.

The decomposition products resulting from vegetable and animal substances are the organic, solid components of the soil, that is to say, humus. This is the dark portion of the soil which is water-insoluble and imparts stability to the crumbs conglomerated by the action of organisms in the soil. Due to the crumb structure, the soil is traversed with cavities which provide it with improved ventilation and permit thorough wetting thereof. Important factors in this connection are the arrangement of the particles, the texture and the distribution of different sized particles in the soil. These factors determine the volume of the hollow space which - dependent upon the condition of the soil - is filled with water or air.

The cavities, interstices and pores of the soil have different shapes and sizes. Large cavities contain little water but are good conveyers of air whilst these characteristics are reversed in small cavities.

The coniferous material produced by the process of the present invention, treated and upgraded in this manner has substantially the same chemical and physical properties as natural humus.

The coniferous material produced by the process of the present invention can also be mixed with peat to form an energy source. Presently, peat is treated by mechanical dewatering and thermal drying and is then processed into a peat mould or mull.

The ground mass of coniferous material, which may have a water content of 25% by weight can be mixed with peat, either partially dewatered to a water content of 70 to 75% by weight or raw peat having a water content up to 90% by weight. The amount of partially dewatered peat added should - 13 be sufficient to produce a mixture having a moisture content of 35 to 65% by weight and the amount of raw peat added should impart a water content of 50% to 75% by weight to the mixture. Such mixing procedure also permits an industrial application of peat as an energy source which has hitherto been impossible due to the high water content of raw peat.

The combination of peat deposits and coniferous material is interesting in many respects. Depleted areas of peat deposits can suitably be recultivated and set-up as conifer plantations and the peat fibers resulting from defibering process of the peat - which are inferior as combustible substances but which are excellent as humus forming peat mull - can be used for fertilising the conifer plantations.

Claims (11)

1. A process for the production of a dust from normally discarded, scantily-wooded, coniferous material selected from twigs, needles, scaly leaves, seed capsules, root stocks, 5 thin roots and mixtures thereof, said process comprising comminuting said material to a coarse product having a particle size of about 10 mm, further comminuting the coarse product to produce a product having a median particle size of 0.5 to 1.0 mm, the dust thus produced being utilisable as a fuel or then 10 being treated to form briquettes, industrial gases or therapeutic agents or, in admixture with peat, fertilisers.

2. A process as claimed in claim 1, comprising the additional steps of treating the product having a median particle size of 0.5 to 1.0 mm to remove adhering fibrils, the treated 15 particles then being admixed with water in an amount sufficient to raise the water content thereof to substantially 70% by weight, the aqueous mixture subsequently being subjected to a still further comminution step to produce a wet dust having a median particle size of 0.001 to 0.5 mm. 20

3. A process as claimed in claim 2, wherein the wet dust produced by the final comminution step is subjected to compaction and is subsequently dried in a hot air stream to reduce the moisture content thereof to 8 to 10% by weight.

4. A process as claimed in claim 1 wherein the dust is 25 treated to form briquettes, such treatment comprising admixing the coarse-grained product with water sufficient to increase the moisture content to substantially 35% by weight, the resulting composition being compacted to form briquettes, and the moisture content thereof being reduced to 20 to 25% by weight. 30 5. A process as claimed in claim 1 or 2 wherein the dust is treated to form industrial gases, the treatment comprising subjecting the dust to gasification at a temperature of from 900 to 1200°C in the presence of a gasification agent, the resultant gases being recovered. 35 6. A process as claimed in claim 1, wherein the dust is - 15 treated to form a fertiliser, the treatment comprising processing admixing the dust with partially dewatered peat having a moisture content of from 70 to 75% by weight, the partially dewatered peat being added in an amount sufficient

5. To impart a moisture content of from 35 to 65% by weight, to the mixture.

6. 7. A process as claimed in claim 1 wherein the dust is treated to form a fertiliser, the treatment comprising admixing the dust with raw peat having a moisture content of sub10 stantially 90% by weight, the raw peat being added to an amount sufficient to impart a moisture content of from 50 to 75% by weight to the mixture.

7. 8. A process as claimed in claim 2, wherein the dust is treated to form a therapeutic agent, the treatment conprising 15 admixing the wet dust with sufficient water at an elevated temperature to form a slurry.

8. 9. A process as claimed in claim 8, wherein said slurry is subjected to filtration, the filtrate obtained therefrom being retained. 20

9. 10. A process as claimed in claim 1 substantially as hereinbefore described and as exemplified in the foregoing Examples.

10.

11. A dust when produced by a process as claimed in claim 1.