RU1778161C - Method for producing fuel briquettes - Google Patents

Abstract

Application: in the fuel industry. The inventive dry powders of not more than 350 microns of wood waste and polyethylene waste are mixed, a mixture of wood waste powder with 40-60 wt.% Polyethylene is heated to melt the polyethylene for 2-5 minutes and then pressed under pressure of 5-15 MPa for 0 , 3 - 0.5 min / mm of the thickness of the briquette, which provides an increase in the calorific value and water resistance of the briquettes. 1 tab.

Description

The invention relates to the field of the fuel industry, in particular to a method for producing fuel briquettes, for example, from waste wood.

A known method of producing fuel briquettes, comprising the following stages: Preliminary preparation of particles of cellulosic material with a dry matter content of 8 to 12% in May., Treatment of wet cellulosic material (with a dry matter content of 55%) with calcium carbonate (in an amount of 2-10% to wet material), which allows introducing up to 5% of calcium on a dry residue, to combine particles of cellulosic material with each other, as well as treatment with sodium silicates, stabilized with alkalis, or with seed oil and related oil in bales (husk, pulp), followed by drying, grinding the cellulosic material up to 4 mm, as well as grinding the thermoplastic material at 20-90 ° C to 4 mm, preparing a mixture of crushed cellulosic material and 1-10% thermoplastic material, pressing briquettes at a temperature of 66 -122 ° C with an additive to form a hydrophobic capsule of a thermoplastic material with a particle size of less than 1.6 mm.

The disadvantages of this technical solution are.

1. Introduction to the composition of fuel briquettes of substances that give harmful products during combustion (copolymers, acrylonitrile, butadiene, styrene, pulp, inorganic

 bavok).

2. A small increase in the calorific value of briquettes compared to the calorific value of cellulosic material, since the addition of a high-calorie thermoplastic material is limited to 10%.

3. Reliable protection of briquettes from moisture. absorption | since not excluded

incorporation of cellulosic material into the surface hydrophobic film at a temperature of 66-122 ° C does not achieve complete melting of the thermoplastic material.

4. Incomplete combustion of thermoplastic material during pressing of briquettes from large particles (up to 4 mm) is not excluded

cl

with

vj h 00

due to the possibility of leakage from the combustion zone under these conditions.

Closest to the described technical solution is a method for producing fuel briquettes, including mixing dry crushed wood waste (bark - less than 25 mm) from May 5-40.% Of crushed (up to less than 6 mm) polyethylene (PE) (as waste film), heating the mixture to 93-204 ° C and the subsequent formation of briquettes at a pressure of 5-15 MPa.

The specified solution has the following disadvantages.

1. Increased emission of harmful products during the burning of briquettes, since the bark, which is part of the briquettes, contains more sulfur and nitrogen-containing substances than wood.

2. The impossibility of introducing more than 40% PE into the briquettes, since during the proposed grinding of PE during combustion, it flows out. This leads to incomplete combustion, an increase in the amount of harmful impurities, a decrease in the calorific value, t .k. the highest calorific fraction of fuel is removed from the combustion zone.

The aim of the invention is to increase the calorific value and water resistance of briquettes and to reduce the amount of harmful combustion products.

The goal is achieved in that in the proposed method for the production of fuel briquettes, including mixing crushed wood waste with a binder, heating the mixture and subsequent briquetting, PE binder powders with particle sizes of not more than 350 microns in an amount of 10 + 60% by weight are used as a binder mixed with a dry powder of wood waste with a particle size of not more than 350 microns, the mixture is heated with hot air at 140-160 ° C for 2-5 minutes and pressed at a pressure of 5.0-15.0 MPa for a duration of 0.3-0.5 minutes per 1 mm of briquette thickness. This makes it possible to increase the calorific value of fuel briquettes, not only due to the increased calorific value of the PE itself (11000 kcal / kg), but also to use more calorific value wood waste by removing moisture from it, which is achieved by drying wood waste. In addition, crushed to 350 μm PE melts upon cutting to 140-160 ° C, impregnates the whole mass of briquette during pressing, and after cooling forms a hydrophobic film that prevents moisture from penetrating wood waste particles. Thus, in the proposed technical solution, the calorific value of the fuel is simultaneously increased, both due to the use of dry wood waste, and due to the high-calorific PE, and

at the same time, the water resistance of fuel briquettes is also increased. At the same time, one of the most important technical problems is solved regarding methods of fire neutralization of waste thermoplastics, organization of complete combustion of PE, since conventional methods of burning PE waste, for example, in waste processing plants, require not only special organization of uniform thermal decomposition of PE, but also uniform supply of products decomposition of (low molecular weight hydrocarbons) into the oxidation zone. And in many countries, PE is used to ensure complete combustion of decomposition products.

special oxygen blasting, since only when pure oxygen is mixed with PE decomposition products is a high-temperature flame zone created, in which it is possible to completely oxidize (to harmless water and carbon dioxide) the intense flow of hydrocarbons obtained by decomposition of PE, Therefore, for efficient and environmentally friendly briquette combustion, containing waste PE, it is necessary to ensure self-regulation of hydrocarbon supply, decomposition into the combustion zone, for example, by organizing capillary recharge, such as It carried out on the known method of burning wax in

a paraffin candle, where liquid products are supplied in a gasification and subsequent combustion zone through wick capillaries.

In the proposed technical solution, the role of capillary wick device

fine wood particles having a higher gasification temperature than PE are produced. This ensures self-regulation of the supply of PE decomposition products to the combustion zone.

The experiments established:

1. It is impractical to introduce PE of less than 10 and more than 60%, since with a less than 10% PE content, briquettes have increased crumbling and water absorption, and their

the calorific value differs little from dry wood, and when the PE content is more than 60%, PE flows out of the briquette during combustion and does not provide a uniform supply of PE decomposition products to the zone

5 burning.

2. It is inappropriate to use PE and wood flour with particle sizes less than 150 microns and more than 350 microns, since finer grinding practically does not affect

on the characteristics of fuel briquettes, and

the use of PE and wood flour with particle sizes greater than 350 microns facilitates the flow of PE from the briquette during combustion and does not provide environmentally friendly burning.

The proposed method for producing fuel briquettes is implemented as follows.

Woodworking waste in the form of shavings or sawn from coniferous or deciduous wood with a moisture content of not more than 18%, crushed to narrow fractions with particle sizes of 150, 250 or 550 microns in a device for producing micropowders with a gapless interaction of working elements, in a dry year stream - carrier (after which the powders had a moisture content of not more than 8%) was mixed with the powder from PE waste in the form of narrow fractions with a particle size of 100; 150, 250, 350 and 500 microns in the ratios 9: 1, 8: 2, 7: 3, 6: 4, 5: 5, 4: 6 and 3: 7 in a mixer with a Z-shaped mixer. Shredding of production and consumption wastes of PE in the form of films, pieces, parts of toys, household appliances, dishes, disposable syringes, textile spools, pressing and crushing of secondary PE of all grades of VD, ND and SD or primary PE in the form of granules was also carried out in a device for producing micropowders with gapless interaction of working elements at a temperature of from 20 to 92 ° C. PE samples had a molecular weight of from 18,000 to 3,000,000 cu, which after grinding decreased by 1.5-2 times.

The resulting mixtures were heated in an air thermostat at a temperature of 150 + 10 ° С for the required time and loaded into a cylindrical mold with a length of 140 and a diameter of 26 mm with a connector along the generatrix, the mold was closed and placed between the plates of a hydraulic press, kept under pressure 5 -15 MPa for 20-30 s with cooling, relieve pressure, open and take out the finished briquette.

The water absorption of the briquettes was determined by immersion in distilled water for 24 hours according to the weight gain.

The strength of fuel briquettes with a PE content of 40-60%:

At a compaction pressure of 15 MPa

tensile 16-15 MPa

with a bend of 19-32 MPa

At a compression pressure of 5 MPa

at a stretch of 7-13 MPa

with a bend of 9-15 MPa

The briquette was also tested for density and crumbling, and also subjected to burning on the grate in the baby stove (Rybolov, 1988, No. 1). Crusability was determined according to GOST 23513-79,

In the manufacture of briquettes, the time by heating with hot air the mixture before 5 pressing should not be longer than the time required to melt the PE particles, i.e. at a temperature of 140-160 ° C it. is within 2-5 minutes, and the pressing pressure can vary between 0 MPa and 15 MPa, since pressing at a pressure below 5 MPa forms a briquette with a lower density and increased crumbling, and pressing at a pressure above 15 MPa does not significantly improve the pressure 5 the number of fuel briquettes in relation to their environmentally friendly burning,

The table shows the properties of fuel briquettes obtained by pressing mixtures of PE powders with particle sizes 0 150-350 microns and wood powders with particle sizes less than 350 microns.

As can be seen from the data in the table, the compositions containing 40.50 and 60 wt.% PE are most effective from the point of view of calorific value and water absorption. For these compositions, the density of briquettes approaches the additive density calculated for the density of air-dry wood porous material, which confirms the effectiveness of the selected conditions. pressing briquettes. Briquettes of this composition are efficiently burned under normal combustion conditions without molten PE flowing out and, after burning 5, the minimum amount of ash is generated, which is formed only due to the ash content of the used wood waste.

In special experiments, it was shown that for heating 2.5 l of water to a boil on a 0 baby stove, 2.2 times less fuel briquettes are required by mass than the well-known fuel for touristic purposes - dry alcohol in the form of standard tablets. In the products of combustion of dry alcohol 5, concentrations of ammonia (MH) and nitrogen oxides (NOX) were found to be 2-3 times higher than the background concentrations, and in the products of the combustion of a suitable gas, concentrations of 0 (SOa) and (MOx) were found, in 1 5-3 times higher than the background, while in the combustion products of the proposed fuel, the concentrations of neither nitrogen oxides, nor sulfur, nor carbon monoxide - (CO) do not differ from the background.

Assessment of pollution was carried out according to the instructions of the Literature source. Methods of analysis of environmental objects. - Novosibirsk: Science. Siberian Branch, 1988-144s.

Thus, the use of the proposed method for producing fuel briquettes provides, in comparison with existing methods, the following advantages:

Implements full processing of harvested wood.

Promotes recycling and fire disposal of PE waste.

It creates a new type of consumer goods, namely environmentally friendly solid fuel with a long shelf life without moisture, including in an environment of high humidity, which can be used in particular as tourist emergency fuel, autonomous expedition fuel, fuel for separate areas.

Claims (1)

SUMMARY OF THE INVENTION A method for producing fuel briquettes comprising mixing dry ground wood waste with ground wood polyethylene waste, heating the mixture before melting polyethylene and subsequent . pressing briquettes under a pressure of 515 MPa, characterized in that, with In order to increase the calorific value and water resistance of briquettes, wood and polyethylene wastes are used in the form of powders of not more than 350 microns, a mixture of wood waste powders with 40-60 wt.% polyethylene is heated to melt the polyethylene for 2-5 minutes and pressed for 0 , 3-0.5 min / mm of briquette thickness. Properties of fuel briquettes from waste wood and PE at pressure pressing 10 MPa