RU2808265C1 - Waste disposal method - Google Patents

Abstract

FIELD: waste disposal.

SUBSTANCE: invention is related to a method for waste disposal and can be used for the disposal of household, agricultural and industrial waste. The method is carried out in a thermoreactor containing three functional zones. The first functional zone is a zone of pyrolysis gases located above the grate. The second functional zone is a fluidized bed zone located near the grate. The third functional zone is a combustion chamber located under the grate. The amount of heat generated by the reactor is determined in advance, and the waste pyrolysis gases are supplied to the zone with a flow rate of up to 12 kg/sec, ensuring combustion of the waste with the heat generated by the reactor. At the same time, a tangential supply of steam with a temperature of not lower than 400°C is provided in the fluidized bed zone and tangential supply of oxidizer to the fluidized bed zone and/or to the combustion chamber. In the fluidized bed zone between the inner surface of the thermoreactor and the grate, an electric field with a voltage of 1 kV to 10 kV is created. Moreover, the electric field is organized with varying intensity in the range (1.0÷2.0)×10⁴ V/cm.

EFFECT: increase of completeness of waste disposal, including wet waste, and increase of efficiency of the method.

7 cl, 2 dwg, 2 tbl

Description

The invention can be used for recycling household, agricultural and industrial waste.

From the RF patent No. 96217 for a utility model, a device for processing household and industrial waste of organic origin is known, containing a pyrolysis reactor consisting of two parts and a system for separating steam-gas pyrolysis products, while a source of electromagnetic influence is additionally introduced into it, installed with the possibility of influencing pyrolysis products in the second part of the reactor, the output of which is connected to the system for separating steam-gas pyrolysis products.

From the RF patent No. 2573137 for the invention, a method for processing and recycling waste is known, including loading waste into a sealed, heat-insulated combustion chamber in which thermal rods are placed, heating the rods with emitters of electromagnetic waves of ultra-high frequency, heating the disposed waste to its combustion temperature, removing combustion products through a channel their discharge into a sealed, heat-insulated afterburning chamber equipped with thermal rods and connected through a pipe to the atmosphere, characterized in that the heating of the rods in the combustion chamber and afterburning chamber is first carried out in the range from 800 to 1200°C, then during heating and combustion of waste in the combustion chamber , as well as when water evaporates from the waste, the pressure of gases and steam in the combustion chamber is increased, for which air is simultaneously or alternately supplied to the combustion chamber under pressure and the heating of the rods in the afterburning chamber is brought to a temperature of 1200-1400°C, the pressure of the combustion products in the chamber is increased combustion until the appearance of volatile components of the combustion products and the appearance of air draft in the afterburning chamber, the combustion products are forced under pressure through a channel from the combustion chamber into the afterburning chamber, where they are afterburned at a specified temperature and neutralized, and then disposed of by release into the atmosphere or into a special container, and the rate of combustion of waste and afterburning of combustion products is regulated by the intensity of the radiation of the emitters and the pressurization of the air supplied to the combustion chamber; during the passage of combustion products in the afterburning chamber, the pressure difference of the combustion products in the combustion chamber and the afterburning chamber is regulated by increasing or decreasing the air pressure supplied to combustion chamber.

The method according to RF patent No. 2573137 was chosen as the closest analogue.

The disadvantage of analogues is their low efficiency, especially when recycling wet waste.

The technical problem solved by the proposed invention is the creation of a highly efficient method for recycling waste, including wet waste.

The technical result achieved by the invention is increasing the completeness of waste disposal, including wet waste, and increasing the efficiency of the method.

The technical result is achieved due to the fact that in the waste disposal method carried out in a thermoreactor containing three functional zones, the first functional zone is a pyrolysis gas zone located above the grate, the second functional zone is a fluidized bed zone located near the grate, the third functional zone is a combustion chamber located under the grate, the amount of heat generated by the reactor is preliminarily determined, waste pyrolysis gases are supplied to the zone at a flow rate of up to 25 kg/sec, ensuring combustion of the waste with the heat generated by the reactor, and at the same time a tangential supply of boiling water is provided to the zone layer of steam with a temperature not lower than 400ºС and tangential supply of the oxidizer to the fluidized bed zone and/or to the combustion chamber; in the fluidized bed zone between the inner surface of the thermoreactor and the grate, an electric field with a voltage of 1 kV to 10 kV is organized, while the electric field is organized with varying voltage in the range (1.0 ÷ 2.0) × 10 ⁴ V/cm.

The oxidizing agent is air.

Steam generated in the first zone of the reactor from heating waste with a humidity of at least 50% and a temperature of up to 900°C is supplied to the fluidized bed zone.

Steam from a steam boiler at a temperature of 450°C is supplied to the fluidized bed zone through a channel made in the wall of the thermoreactor.

Steam generated in the first zone of the reactor from heating waste with a humidity of at least 50% and a temperature of up to 900°C is supplied to the fluidized bed zone; at the same time, steam from a steam boiler with a temperature of 450°C is supplied to the fluidized bed zone through a channel made in the wall of the thermoreactor .

The electric field is organized due to external sources of electromagnetic radiation; for this purpose, the surface of the thermoreactor in the area where the electromagnetic field sources are located is made transparent to electromagnetic radiation.

The electric field is organized in the form of a static electric field by making the upper part of the grate in the form of a truncated cone expanding downwards with slots, by making the lower part of the grate cylindrical with slots along the cylindrical surface, and also by making the internal surface of the thermoreactor electrically conductive.

In fig. Figure 1 shows a cross-section of a thermoreactor for implementing the proposed method.

In fig. 2 is a cross-section of a thermoreactor illustrating the tangential supply of steam and air.

The inventive method was carried out on an installation (thermoreactor), a schematic view of which is shown in Fig. 1 and 2.

The thermoreactor contains a housing 1, a cover 2 with a hole 3 for loading waste, a grate 4 with slots 5 in the upper part 4.1 in the form of a truncated cone and in the lower cylindrical part 4.2; channel 6 for supplying steam from the steam boiler, channel 7 for supplying air; electrodes 8; pipe 9 for flue gas outlet; slag outlet pipe 10; pipes 11 for the outlet of pyrolysis gases.

The thermoreactor is divided into three functional zones: the first functional zone A is a zone of pyrolysis gases located above the grate 4; the second functional zone B is a fluidized bed zone located near the grate 4; the third functional zone B is a combustion chamber located under the grate 4.

Waste, regardless of its physical state (solid, liquid, gaseous) enters a waste reception unit (for example, Silo SS TU25.29.11-001-32459602-2015), in which waste to be disposed of is accumulated. The characteristics of raw materials sent for disposal are determined and their compliance with the requirements is established.

If the parameters of the raw materials do not meet the established requirements, the raw materials are sent to a waste processing unit (for example, the 7GReenLine-M waste sorting line at the Textile Mash plant in Kolomna; shredder processing, for example, the TX-800 twin-shaft shredder of Siberian Polymer Company JSC) In the waste processing unit, the composition of the raw material is adjusted in order to ensure its required properties. The processing of raw materials is carried out by, for example, separation/separation of fractions of raw materials (waste), by neutralizing waste by any known method (thermal, chemical methods can be used). Also processing of raw materials can be carried out by crushing/grinding, averaging, screening, etc.

Raw materials, in a condition that meets the requirements, enter the raw material collection bunker for its subsequent transportation to the thermoreactor.

Raw materials enter the reactor in accordance with established rules, namely: the amount of raw materials supplied must be proportional to the amount of thermal energy generated by the reactor. To do this, the amount of heat generated by the reactor per unit volume of the reactor is first determined. In general, waste flow should not exceed 12 kg/sec for an installation with a capacity of 5 t/h; for an installation with a capacity of 10 t/h, waste consumption should not exceed 25 kg/sec; for an installation with a capacity of 3 t/h, waste consumption should not exceed 7 kg/sec;

Compliance with the specified rule, which determines the amount of raw material supplied to the thermoreactor per unit of time, makes it possible to eliminate the imposition of additional requirements on the raw material related to the presence of the raw material’s own heat of combustion. Therefore, in the inventive method it is possible to use raw materials with any calorific value, which can vary over a wide range.

Raw materials enter the reactor, as a rule, through the upper part of the thermoreactor, in which the process of destruction of raw materials occurs at temperatures above 1200 ° C and a pressure of 0.02-0.05 MPa.

The thermoreactor provides a combined effect on raw materials in the form of a combination of thermal and electromagnetic effects.

The initial cold start of the destruction processes in the reactor is ensured by the ignition unit, which can operate on any type of fuel (solid, liquid, gaseous). The process of self-sustaining destruction of incoming raw materials begins when the temperature of the incoming raw materials is above 400°C. Therefore, after reaching the specified temperature, the supply of fuel to the reactor from the ignition block is stopped.

The operating mode of the rector is maintained depending on the type of incoming raw materials by a gate valve, through which the amount of supplied raw materials is regulated in a set quantity.

An urgent task from the point of view of increasing the energy efficiency of the waste recycling process is to increase the yield of pyrolysis gases. It is known that the yield of pyrolysis gases is increased due to gasification of the solid carbonaceous residue, which, after separating the inorganic fraction from it, is fed into the gasification reactor together with steam and oxygen. The resulting synthesis gas, containing hydrogen, carbon dioxide, carbon monoxide and water vapor, is fed into the pyrolysis reactor ().

Waste gasification is the high-temperature transformation of organic components into a flammable gas consisting of CO and H ₂ in the presence of an oxidizing agent (gasifying agent). The waste gasification process using a steam-air mixture as a gasifying agent requires a temperature of at least 600°C.

Gasification can be considered as incomplete oxidation of carbon. The most common oxidizing agents are oxygen and water vapor. However, when carbon is oxidized with pure oxygen, the temperature in the reactor is too high, so air, a steam-oxygen or steam-air mixture is usually used as a gasifying agent (blown). The heat of combustion of the product, gas, is higher if it is produced by steam-oxygen gasification. During air or steam-air gasification, the resulting gas contains a significant amount of nitrogen and has a lower calorific value.

In the proposed method, steam supply can be organized in three ways:

- from heating waste with a humidity of at least 50%, while the temperature of the resulting steam is up to 900°C. In this case, the tangential supply of steam is ensured by the design of the grate - it is made in the form of a truncated cone, expanding downward. Accordingly, the direction of steam coming from the top of the thermoreactor will be tangential to the surface of the grate.

- through a special channel for supplying steam from a steam boiler with a temperature of up to 450°C. The tangential supply of air and steam is ensured by creating the corresponding channels as shown in Fig. 2;

- simultaneous supply of steam from the first zone and from the steam boiler.

Steam and air supplied tangentially to the boiling zone of the thermoreactor (which can also be supplied to the combustion chamber under the grate) organize a vortex flow with a steam wall layer, significantly activating the gas flow throughout the entire volume of the reactor.

To intensify the process of gas destruction in the volume of the thermoreactor, an electric field with a voltage of 1 to 10 kV is created.

The influence of the electric field on the destruction of gases formed during the combustion of waste is known.

In the proposed method, an electric field with different strengths is organized (range (1.0 ÷ 2.0)×10 ⁴ V/cm) in order to provide a stable electrical discharge throughout the entire volume of the fluidized bed zone, depending on the geometry of the grate.

It is possible to provide a uniform electric field with a obviously higher intensity in order to ensure a stable electric discharge throughout the entire volume of the fluidized bed zone. However, in this case there will be an increased consumption of electrical energy necessary to create an electric field, which will significantly reduce the efficiency of the waste disposal process.

The organization of an electric field with a intensity varying in the range (1.0 ÷ 2.0)×10 ⁴ V/cm makes it possible to ensure the necessary and sufficient consumption of electrical energy for a stable electrical discharge throughout the entire volume of the fluidized bed zone.

The required tension is organized by the location of the sources of electromagnetic radiation and the value of their output parameters. The electrodes in this case are both sources of electromagnetic radiation and/or the internal casing of the thermoreactor, and the surface of the grate, between which a potential difference must be provided in the range, for example, from 400 to 800 V. Such a potential difference is sufficient to ensure a stable electrical discharge of about grate zone (in the fluidized bed zone). In this case, the insulation resistance between the electrodes must be at least 20 MOhm.

The required electric field strength can be ensured even in the absence of special sources of electromagnetic radiation, but only through the creation of static electricity from the vortex flows of the generated flue gases and combustion products colliding with the surface of the grate.

To ensure the necessary electric field due to static electricity near the grate, firstly, they provide the necessary speed of steam and air supply (determined by calculation), as well as the geometry of the grate, made with slots both in the upper cone-shaped part and in the lower cylindrical part parts.

Making a grate consisting of two parts (cone-shaped and cylindrical), as well as making these parts with slots, is designed to significantly increase the residence time of flue gases and combustion products in the fluidized bed zone (in the vicinity of the grate zone), since during the collision of flue gases and products combustion on the grate produces static electricity, eliminating the need to use external sources of electromagnetic radiation.

Moving in an electric field, electrons acquire energy exceeding the threshold ionization energy of neutral gas particles (molecules) and ionize them, which leads to the formation of so-called “secondary” electrons and the development of an electron avalanche. As a result, a nonequilibrium low-temperature plasma with a temperature of more than 3000°C is formed.

The plasma zone is a source of chemically active particles, as is the case in the type of discharge with metal electrodes described above. Positive ions with energy reaching hundreds of electron volts bombard the waste products in the fluidized bed, causing a number of important effects. The first of these is the emission of electrons necessary to maintain the discharge. The vapor generated during electric discharge has a significant effect on the composition and properties of the plasma.

Water vapor supplied to the fluidized bed zone (in both cases of formation of an electric field) promotes the electrolysis of flue gases due to the formation of static electricity discharges between the grate and the inner surface of the thermoreactor, which are, respectively, the cathode and anode. Those supplied to the fluidized bed zone help to increase the potential difference between the surface of the grate and the internal surface of the thermoreactor (which is electrically conductive) to 10 kV, further increasing the process of intensifying the destruction of flue gases generated during waste combustion.

At the same time, intensification of destruction is ensured in a fairly simple way, which is not energy-intensive and energy-intensive, contributing to the effectiveness of the proposed method.

The presence of a constant electric field in the atmosphere of flue gases and steam supplied to the fluidized bed zone leads to the formation of oxygen and hydrogen. When hydrogen burns, thermal energy is released, hydrogen burns and provides additional calories in the fuel mixture in the fluidized bed zone, and oxygen increases the volume of air in the fluidized bed zone, promoting better and complete combustion of waste. At the same time, the fluidized bed zone “receives” oxygen from the air supplied either directly to the fluidized bed zone or to the combustion chamber (under the grate zone).

Air can be supplied through VDN-10 units.

The effectiveness of the proposed method was tested on the Installation of the company JSC "Fond Compass" SNPO.90.00.00.000 with characteristics in accordance with Table 1.

Table 1

No. Indicator name Indicator value 1 Productivity, t/h 5 2 Degree of destruction (processing), %, not less 99 3 Thermal power, kW/hour, not less 10,000 4 dimensions
of 9 twenty-foot containers, mm
(width Length height) 4800 x12000 x10200 5 Structural weight, kg, no more 42,000 6 Network settings rated voltage, V 220/380 frequency Hz 50-60 7 Efficiency, %, not lower 65 8 Operating pressure in the reactor, MPa (kgf/ ^cm2 ) – nominal 0.002(0.02) – maximum 0.005(0.05) 9 Time to reach operating mode, minutes, no more 60 10 Time of continuous operation before major repairs, hour, not less 40,000 eleven Maximum power consumption, kW 130 12 Installed power, kW 90 13 Service personnel, persons/shift 2 14 Maximum flue gas temperature), °C 1300 15 Hazard level of recycled waste 2-5 classes
GOST 12.1.007 16 Types of waste Industrial and household waste 17 Maximum permissible moisture content of raw materials, % 100 18 Requirements for preliminary waste sorting 1. Removal of metals and construction waste
2. Creation of a homogeneous mass using a shredder 19 Generated electrical energy, kW per hour From 500 to 1000 20 Transfer of thermal energy (coolant water:
Т=115 0С, Р= 5Bar), MW per hour Up to 8

During the experiment, the following parameters were set:

- waste consumption for an installation with a capacity of 5 t/h was 12 kg/sec; for an installation with a capacity of 10 t/h, the waste consumption was 25 kg/sec; for an installation with a capacity of 3 t/h, the waste consumption was 7 kg/sec.

Electric field parameters (Table 2):

No. Name Dimension Magnitude Potential difference kV 10 Insulation resistance between electrodes MOhm 20 Frequency range MHz 2500 + 250 Pulse repetition rate Hz 400 Impact pulse duration 10 ^-3 s 2-3 Pulse power W 1000 Exposure (grid surface area 2.8 ^m2 ) W/ ^m2 357

Measurements were made at a productivity of 10, 5 and 3 t/h for the disposal of municipal solid waste. The results are shown in Table 3

Name of the indicator being determined Mass concentration of pollutant at normal conditions, mg/m ³ Humidity,
% Massive release of pollutant, 10 t/h 5 t/h 3 t/h Nitrogen oxide 44 ± 10 90 0.00209 0.00118 0.00101 Nitrogen dioxide Less than 10 0.01286 0.00976 0.00798 Carbon oxide 93 ± 12 0.02232 0.02211 0.01783 Sulfur dioxide 45 ± 25 0.01080 0.08769 0.00879 Dust (suspended solids) 104 ± 12 0.02486 0.01765 0.01459 Soot (carbon) 7.6 ± 1.3 0.00209 0.00154 0.00078 Benz(a)pyrene 0.000210 ± 0.0000530 0.00000050 0.00000042 0.00000039 Hydrogen fluoride 0.75 ± 0.19 0.00018 0.00015 0.00014 Hydrogen chloride 0.31 ± 0.08 0.00007 0.00005 0.00004 Formaldehyde 0.07 ± 0.02 0.00002 0.00002 0.00001 Hydrocarbons C12-C19 1.12 ± 0.28 0.00027 0.00023 0.00019

Thus, the proposed method provides high efficiency in waste disposal, including wet waste.

Claims (7)

1. A waste disposal method carried out in a thermoreactor containing three functional zones, the first functional zone is a zone of pyrolysis gases located above the grate, the second functional zone is a fluidized bed zone located near the grate, the third functional zone is a combustion chamber , located under the grate, the amount of heat generated by the reactor is preliminarily determined, the waste pyrolysis gases are supplied to the zone with a flow rate of up to 12 kg/sec, ensuring combustion of the waste with the heat generated by the reactor, and at the same time a tangential supply of steam with a temperature not lower than 400°C and tangential supply of the oxidizer into the fluidized bed zone and/or into the combustion chamber, in the fluidized bed zone between the inner surface of the thermoreactor and the grate, an electric field with a voltage of 1 kV to 10 kV is organized, while the electric field is organized with a varying intensity in the range (1.0 ± 2.0)×10 ⁴ V/cm. 2. The method according to claim 1, characterized in that the oxidizing agent is air. 3. The method according to claim 1, characterized in that steam generated in the first zone of the reactor from heating waste with a humidity of at least 50% and a temperature of up to 900°C is supplied to the fluidized bed zone. 4. The method according to claim 1, characterized in that steam from a steam boiler at a temperature of 450°C is supplied to the fluidized bed zone through a channel made in the wall of the thermoreactor. 5. The method according to claim 1, characterized in that steam generated in the first zone of the reactor from heating waste with a humidity of at least 50% and a temperature of up to 900°C is supplied to the fluidized bed zone; at the same time, steam from a steam boiler is supplied to the fluidized bed zone with a temperature of 450°C through a channel made in the wall of the thermoreactor. 6. The method according to claim 1, characterized in that the electric field is organized due to external sources of electromagnetic radiation; for this purpose, the surface of the thermoreactor in the area where the electromagnetic field sources are located is made transparent to electromagnetic radiation. 7. The method according to claim 1, characterized in that the electric field is organized in the form of a static electric field by making the upper part of the grate in the form of a truncated cone expanding downwards with slots, by making the lower part of the grate cylindrical with slots along the cylindrical surface, and also due to making the internal surface of the thermoreactor electrically conductive.