IT202000002806A1 - MOBILE WASTE TREATMENT PLANT - Google Patents

Description

DESCRIPTION of the industrial invention entitled:

"MOBILE WASTE TREATMENT PLANT"

TEXT OF THE DESCRIPTION

The present invention refers to a mobile waste treatment plant.

In particular, the invention relates to a system designed for the treatment of solid and pasty waste, with a capacity? total thermal of about 6.6 Mil Kcal / h.

Known systems require long times and high installation costs which may not be justified by the necessary requests.

Task of the present invention? to create a system characterized by a quick and easy installation.

Within the scope of this task, an important object of the invention? that of creating a system designed and sized with the highest degree of assembly and which can be installed without additional infrastructures.

Another purpose of the invention? to create a system that can be adapted to different types, conformations and characteristics of the terrain.

An important purpose of the invention? to build a plant that can be easily transferred from one site to another and quickly put into operation on the new site.

A further purpose of the invention? that of creating a plant with a wide range of operations; in fact the plant,? was designed to work without infrastructure, such as warehouses.

A further purpose of the invention? that of creating a system capable of operating in different climatic conditions, from -40? C to 40? C of external temperature.

Another purpose of the invention? that of creating a system with extremely reduced disassembly and reassembly times.

These purposes and others which will appear better later, are achieved by a mobile waste treatment plant characterized by the fact that it comprises a plurality of waste. of functional components arranged on rubberized means.

Further characteristics and advantages will become clearer from the description of preferred, but not exclusive, embodiments of the invention, illustrated by way of non-limiting indication in the accompanying drawings, in which:

figure 1? a plan view of an embodiment of a plant according to the invention;

figure 2? a perspective view of the essential components of the system;

figure 3? a side elevation view of a component of the plant, the rotary drum kiln;

figure 4? a plan view of the rotary drum kiln. With reference to the aforementioned figures, the plant according to the invention, generally indicated with the reference number 1 comprises a plurality of elements. of components each of which? arranged on a rubberized vehicle, generally indicated with the reference number 100.

The wheeled vehicles are normalized and in shape and allow a rapid movement on the road, without the need? of stock and limitation of speed ?.

In the example illustrated, the system components are nine, however the number of components can? be varied according to the needs.

In this case, the components of the system are the following, each of which is incorporated in a semi-trailer:

a rotary drum furnace, indicated with the reference number 9,

a first section of the post-combustion chamber, indicated with the reference number 12,

a second section of the post-combustion chamber, indicated with the reference number 121,

an air / fumes exchanger,

a boiler,

a dry flue gas treatment plant, indicated with the reference number 14,

a wet flue gas treatment plant, indicated with the reference number 15,

a control room, indicated with the reference number 19, and distributed control and pollutant monitoring systems, and a generator and general plant services.

According to the illustrated embodiment example, the overall surface of the system, including the maneuvering spaces,? of about 1500 square meters.

The planimetric arrangement of the plant and the design of the various assembly components, that is? the connections, pipes, cables, ducts and connections are configured in such a way as to minimize disassembly and reassembly operations during the transfer of the system.

A practical embodiment of the plant is described in detail below, purely by way of example.

The embodiment of the plant according to the invention? designed for the treatment of solid and pasty waste with a capacity? total thermal of about 6.6 Mil Kcal / h.

For incineration, a rotary kiln is provided, indicated with the reference number 9, operating in counter-current or in co-current, in order to optimize the inertization of ashes and slags.

The rotary oven 9? made in such a way as to allow discontinuous operation with particular reference to the refractory lining, which? such as to minimize thermal shock problems, thus allowing rapid switching on and off of the system without the risk of wear of the refractory itself; moreover, the refractory lining must actually allow the carrying out of the transport operations without being damaged by the mechanical stresses that are unavoidable in such situations.

The rotary oven 9 can? be managed with different operating temperature ranges in order to perform the thermal treatment of inert materials with organic pollutants (for example reclamation earth, filtration media, etc.), the combustion of special and toxic-harmful waste and the treatment of waste and combustion residues in general. In any case, the furnace must be able to be managed in such a way as to obtain sintering of the slag.

The waste-to-energy process of liquid waste? obtained by means of a burner with compressed air atomization system; the different pumpable effluents are fed to the burner through a multi-channel system.

The same constructive criteria indicated for the rotary kiln are applied for the realization of the post-combustion chamber, which will present? an additional problem in the case of operation at 1200? C represented by the molten slag that will have to? be collected and discharged at the base of the first vertical section.

Particular attention? been given to the complete automation of the system.

Two systems are envisaged for the treatment of the fumes: dry treatment consisting of a filtration system equipped with dosing of both organic and inorganic adsorbent products and with an automatic backwashing system;

wet flue gas treatment, carried out in two successive process phases, the first in an acidic environment and the second in a neutral (slightly acidic) environment; also in this case ? the dosage of chemical products is foreseen; the first stage? designed in particular for the treatment of strong acids (HCl and HF) the second for the abatement of SO2.

The waste water resulting from the washing of the fumes is collected in a special container to be given to third parties to be then treated and disposed of.

The plant? designed and dimensioned in such a way as to be supplied completely assembled and installed on standardized trailer trolleys avoiding "out of shape".

All auxiliary systems are installed on board the system, with the same criteria as a system mounted on a skid.

The connection systems between the various plant sections are pre-assembled and easy to assemble in order to minimize the installation and start-up times of the plant.

The systems adopted for the treatment and control of emissions ensures compliance with the most? restrictive provisions on the subject currently in force.

Peculiar characteristics of the rotary kiln

The embodiment exemplified here? oriented to the use of a rotary kiln, based on the consolidated experience on this type of kiln already? functioning in many countries.

Finally, this type of oven? particularly suitable for the treatment of reclamation lands and the thermal inertization of waste from incineration, industrial waste and sludge so? such as hospital waste, municipal solid waste as it is or pre-selected and RDF.

The main advantages of the rotary kiln system are: thermoconversion of a large variety? of waste regardless of physical state;

thermoconversion passing through a fusion phase; capacity to receive bulky materials as feed; adaptability to a great variety? of power supply systems; high turbulence and exposure to air of solid waste; continuous removal of ash, which does not interfere with the oxidation of the waste;

control of the residence time of a non-volatile sample by adjusting the speed? of rotation;

direct feeding of the waste into the oven without any preparation (preheating, mixing, etc.).

The rotating oven? a cylindrical reactor, internally lined with refractory material, mounted slightly inclined with respect to the horizontal plane.

The rotary oven can? be lined internally with easily interchangeable special steel plates; this type of coating makes it possible to control the temperature of the material which is directly in contact with the furnace wall, thus controlling? the physical state of the same.

Furthermore, a high mechanical resistance is obtained on the internal walls, which is necessary above all for the treatment of heterogeneous material containing bodies (including metal) of various weight and nature.

? possible to prevent that the material to be thermally destroyed is liquefied, thus incorporating? unburnt carbonaceous substances (unburnt organic) which would interfere with the quality? of the waste produced by combustion.

At the onset of liquefaction phenomena of materials highlighted by temperature control? It is possible to intervene by abruptly lowering the temperature itself. There? ? made possible by the type of refractory used in the oven which is not affected by thermal shock.

By lowering the temperature, the physical state of the waste is affected in this case by re-solidifying, with the consequent production of vitrified waste.

Thermal insulation? made with special light refractories (ceramic) placed between the inner lining and the outer shell. Do you get so? mechanically very resistant systems and practically insensitive to thermal shock.

These constructive characteristics allow to manage the furnace even with discontinuous operation (which is absolutely impossible with rotary furnaces internally lined with conventional refractory material).

It should also be emphasized that this type of coating? particularly suitable for a unit? transportable or mobile, as it easily withstands the mechanical stresses caused by road transport.

Finally, two fundamental advantages of this type of coating should be mentioned, especially in relation to the construction of a unit? which are the dimensions and weight considerably reduced compared to conventional refractory linings.

The variation of the speed? rotation allows to control the residence time of the waste in the combustion chamber and the mixing with the combustion air.

The reactor can? work with two flow schemes: in co-current and in counter-current. For a waste that thermally degrades correctly, the flow scheme adopted is not? important, as both types of oven can destroy the waste.

Same thing can not? say for low combustibility waste? (sludge) or waste with high production of slag: for this? has the basic countercurrent operation been correctly chosen for the realization of the unit? waste-to-energy cabinet that offers the advantage of better temperature control at both ends? resulting in less danger of overheating of the refractory lining and makes it possible to influence the quality? slag by adjusting the burner in a targeted manner in the last segment of the drum.

The flow in countercurrent due to the higher speeds? associated also increases turbulence during combustion, which generally? a desirable factor.

The main advantage of countercurrent flow? for? the fact that ashes and slags pass through the area pi? hot and more oxygenated before being sent to the drain; this fact absolutely guarantees the absence of unburnt organic products and allows to manage the furnace in order to obtain sintered and inertized slag.

The system ? in any case, made in such a way that it can also be managed in co-current, after intervening on the provisions of the equipment.

The residence time of the material varies from a few seconds, for highly combustible gases, to a few hours for low combustible solid waste.

The solid waste is fed to the oven, where possible, through a variable pitch screw with speed? and adjustable flow, thus obtaining? the possibility? to adjust the flow rate automatically based on the combustion data.

Where necessary, the solid waste is screened for the separation of bulky materials and ground with a shredder before being fed into the auger hopper.

The oven ? equipped with a multi-channel lance burner for diesel operation to ensure initial heating, to maintain stability? of the flame and, if necessary, to provide additional heat. Said burner? made in such a way that it can also be fed with alternative fuels and high caloric power wastewater; the liquid waste with low caloric power will be fed by means of special lances installed on the head.

The collection of ashes and slag takes place through an unloading system with dry or wet seal on special steel belts for the conveyance of said materials in special containers.

The plant? was designed paying the utmost attention to the concept of operating safety also and not only as regards the functional side of the thermoconversion sector and its post-combustion stage, where temperature and residence times imposed by current legislation cos? as the high speeds? in entry to the system damage per se? the maximum guarantees.

Before moving on to the general description, some characteristics of the system are underlined below, concerning in particular the thermoconversion phases and automation.

The fully computerized combustion control is not based exclusively on temperature and free oxygen measurements, but also on instantaneous process data such as flow rate, pressure, etc.

Therefore, we do not limit ourselves to detecting a certain course of the reaction, but said course is constantly compared to the theoretical data set, thus obtaining? the possibility? to foresee any problems without incurring blocks and / or alarms.

How does the combustion take place in the rotary kiln? also controlled by special sensors placed on the internal walls to prevent encrustation problems.

The control system of the rotary kiln? complemented by a closed circuit television system.

? the utmost importance has been given to the complete automation of the entire system so yes? reached the integration between the parameters relating to the management, management and control of the process, having cos? continuously available all data.

The sizing of the combustion air supply and flue gas treatment systems must necessarily refer to average values. For this reason ? it is necessary to balance any differences in the composition of the various types of waste through proper management.

Working with potential? intermediate, the dimensional characteristics of the kiln do not change, as well as the percentages of materials that can be disposed of with the waste-to-energy plant.

Post-combustion chamber

The combustion gases coming from the rotary drum furnace are conveyed to a post-combustion with a fully automated and modulating combustion regulation system made in two segments; the first, fed in such a way as to obtain a turbulent and cyclonic flow,? positioned vertically to facilitate the collection and discharge of molten slag; the second section, on the other hand, is installed horizontally.

The exhaust gases produced by primary combustion are sent to the post-combustion chamber, which is sized to obtain the total destruction of any organic component remaining unburned after the primary combustion process.

Said room? dimensioned for a residence time of the combustion gases of 2 seconds, an operating temperature of 950? C while the section of inlet of the exhaust gases in the post-combustion chamber guarantees a speed? of flow greater than 10 m / sec.

This post-combustion chamber? equipped with a modulating burner with automatic and computerized regulation, fed with conventional fuel: a free oxygen control system? in charge of regulating the intake of combustion air in such a way as to guarantee an output value that is certainly higher than 6% of free oxygen referred to the exhaust gases.

The post-combustion chamber? divided into two sections, the first with downward flow and the second horizontal.

Do you get so? several advantages:

also in this case the stresses on the refractory material are minimized;

the unloading of the melted slag in a special ladle is simplified; in this way an optimization of the distribution and mixing of the combustion gases is obtained by imposing a reversal of direction on the gas flow;

the support burner? in a central position while the excess air for the regulation of free oxygen is introduced tangentially.

The post-combustion chamber? designed for an operating temperature of 950-1200? C and? made of sturdy steel carpentry. The internal insulation material? consisting of a silico-aluminous refractory lining with high abrasion resistance with an aluminum content> 60%.

This refractory material has a thickness of about 130 mm.

The introduction of the fumes coming from the rotary kiln takes place through an inlet section sized to ensure a speed? fumes always higher than 10 m / s; moreover, the tangential entrance determines a vortex that creates a high turbulence of the fumes. The fluid regime that is determined? guarantee of an intimate mixing of the fumes with the secondary air, which allows the total oxidation of any unburnt substances present in the fumes.

The development of the second section in a direction orthogonal to the first section also determines a phenomenon of flow inversion of the smoke stream which, in addition to avoiding preferential paths of the fumes themselves, involves a further phenomenon of turbulence. In this way, adequate turbulence suitable for obtaining the complete decomposition of the organic substances present in the aeriform is guaranteed along the entire path of the fumes in the post-combustion chamber.

On the head of the cylindrical section, second section,? the connection for the emergency chimney is foreseen.

The emergency can? be determined:

the overpressure conditions in the first section and / or in the ducts downstream of the post-combustion chamber outlet (the overpressure may occur in the case of blocking of some of the sections such as heat recovery and / or depoveratore);

from a black out of electricity;

from overheating of the fumes entering the panel filter. In case of occurrence of the event, the block of the waste feeding, both solid and liquid, is immediately activated and the emergency opening is automatically activated for the natural outflow of the fumes.

The emergency, clearly of an exceptional nature, could? have a maximum duration of 15-20 minutes, that is the strict technical time necessary for the inertial combustion of the solid waste present in the rotating drum.

The sizing of the post-combustion chamber? was carried out taking into account the legal parameters. The flow rate of the fumes coming from primary combustion and entering the post-combustion? equal to 17,500 Nmc / h.

Such a flow of fumes? including the excess air necessary to ensure correct combustion as well as? the residual free oxygen content exceeding 6% by volume.

The flow rate of the fumes at a temperature of 950? C? equal to 74800 mc / h corresponding to 21.7 mc / s. The useful volume of the post-combustion chamber? equal to 65 cubic meters.

The fumes, therefore, will be kept at a temperature of 950 ° C for a time equal to 2,995 seconds.

The size of the room? was therefore taken in an extremely precautionary manner in order to ensure that the minimum conditions envisaged by the technical regulations in force are respected in any operating condition.

Smoke cooling system

The fumes coming from the post-combustion chamber have a temperature of about 1200 ° C and are cooled by means of a heat exchanger and subsequent recovery boiler.

The gases leaving the cooling section are conveyed to the fumes treatment system.

Integrated smoke treatment system

As regards the fumes treatment system, two series treatment systems are considered:

the first involves a system of dry dedusting and absorption by means of a panel filtration system with dosage of suitable additives for the separation and absorption of HCl, SO2, HF, etc .; said section? designed both for the fine dedusting of combustion gases and for the chemical treatment of neutralization, oxidation or reduction of the inorganic components present;

the second, what can? also be considered as an emergency system,? consisting of a wet treatment system at pi? phases in which it is expected that the gases are first sent to a quenching system for cooling and saturation equipped with a venturi throat, and then move on to a two-stage contact washing system in an acidic and neutral or slightly acidic environment made so as to to be able to carry out chemical conditioning of gases.

The washing system will allow? in the future to be eventually implemented with a system of abatement and elimination of mercury.

To reduce the concentration of NOx, the plant can? be equipped after the post-combustion chamber, of a treatment phase which consists in the introduction, in pi? specific points, of a solution of water and ammonia at a temperature of about 850/900 ° C.

Under these thermodynamic conditions, the NOx reduction reaction that may be present and eliminated from the system in the form of molecular nitrogen (N2) takes place.

Dry flue gas treatment section

The dry treatment? carried out on a panel filter with additives dosage.

The absorption process occurs inside highly reactive microporous particles with internal surfaces (capillaries) up to 1.5 m <2> / g.

These capillaries have a diameter in the order of angstroms. The substance in the gaseous phase reaches by diffusion the internal surface of the adsorbent material and from there, by further diffusion through the pores (larger), it diffuses up to the small micro-cavities, where? retained (capillary condensation).

To achieve good separation efficiency? in addition to maintaining a certain temperature range, it is necessary to create the following conditions:

good mixing of the gas with the additive;

good mechanical abrasion of the surfaces of the additive in order to continuously obtain new reaction surfaces;

high density of the additive;

large reaction surface.

In practice, calcium-based products are used as additives. Calcium hydrate, with its large specific surface of 2-15 m <2> / g, offers the best conditions.

The gases react with the calcium hydrate in the following sequence SO2- HCl - HF.

The hot and dust-laden exhaust gases, after being cooled to the necessary reaction temperature, arrive in the reactor where the gas is mixed with the added additive.

By means of intensive mixing lines, as well as swirling systems, the gas? brought into intimate contact with the additive.

SO2- HCl - HF are deposited on the additive particles.

According to the quantity? of gas dust bound to the additive a part? recycled upstream of the dry treatment plant with a pneumatic conveying system.

By recycling part of the additive, optimal use is achieved which reduces the consumption of fresh additive.

With a variable speed motor is the quantity calibrated? dispensed by the dosing spiral according to the needs.

The additive fed by the dosing screw is introduced into the reactor through a pneumatic transport system and an injector.

? the opportunity has been evaluated? to provide for the use of activated lignites or activated carbons in the filtration phase.

The very low volatile fraction present in these products and the relatively high ignition temperature allow their safe use in flue gas treatment plants, observing certain technological conditions and ensuring accurate control of the CO concentration.

Numerous tests have demonstrated the efficiency of these products for the separation of a series of components such as SO3, HCl, HF, NH3, basic amines and heavy metals present in gaseous form (with particular interest for mercury).

Said additives also improve the efficiency of filtration of fine powders and with them of metals "bound" to particles such as Cd and Pb.

Of particular interest? the capacity? retention of organic compounds such as dioxins and furans.

Which panel filter used? of the type with automatic air backwash and? designed to run continuously.

The aeriform to be treated enters the filter chamber through a special distribution system and then passes from the outside to the inside of the panels. The dust is deposited on the external surface from which it is removed and dropped towards the lower part of the filter by means of the backwash air flow.

Thanks to the injector effect, the air drags a certain amount? of purified aeriform: the backwash is therefore carried out at a temperature practically equal to that of the filter, avoiding dangerous condensation effects.

The powders are collected in the hoppers and are discharged by means of a rotocella.

Downstream of the filter? positioned a fan with sufficient head to overcome the system pressure drops.

Wet flue gas treatment section

The line for the wet treatment of exhaust gases, coming from the filtration and absorption line,? instead structured as follows.

The fumes, after a cooling phase through a quenchventuri, pass to a cross-flow contact washing system structured on two separate stages: the first managed as an acid wash, the second as a neutralization or slightly acid wash, with automatic systems. for pH control and regulation. The washing solutions of the two stages are managed separately.

This washer can be fed with different solutions according to the treatment required by the aeriform that will depend? in turn from the materials fed to the incineration system.

The washer? made in antacid execution and d? designed to work with a pressure drop d? about 150 mm of H2O.

The washer? completed by a lamellar-type droplet separator.

The water used for the fumes washing phases can be neutralized in a special reactor and partially recycled.

The fumes coming out of the contact washing are discharged through a chimney, globally indicated with the reference number 16, after heating by means of a tube bundle exchanger, fed with overheated fumes to avoid the formation of the characteristic white plume due to the saturation of the fumes, especially in periods winter.

The plant d? fumes treatment works in depression through fans placed downstream of the final washing.

Exhaust chimney

The chimney, from where the fumes are introduced into the atmosphere, is the only emission point of the waste-to-energy system.

Fireplace ? equipped with the following components:

inspection hatch;

external marine staircase up to a height of about 10 m with relative protection cage;

platform positioned to allow access to the emission sampling systems for the required analytical controls; continuous detection, analysis and recording system of the concentration of the following pollutants: dust, hydrochloric acid, nitrogen oxide, total organic carbon, sulfur oxide;

? also foreseen the continuous detection of: temperature, humidity, pressure, speed.

Such instrumentation? prepared to be connected to the provincial air pollution detection network, according to the times, the modalities? and the forms that the competent bodies will have.

? finally, the detection and recording of temperature and oxygen in the fumes is envisaged in order to have an immediate reference parameter for verifying compliance with the authorization requirements.

The fireplace 16? constituted in two trunks and? self-supporting.

The equipment includes a monitoring system, indicated with the reference number 17, which checks the emissions of hydrochloric acid, nitrogen oxides, carbon monoxide, carbon dioxide and sulfur oxides, referred to the concentration of oxygen, in the fumes emitted by the incineration group cos? articulated:

A) sampling system,

B) sample conditioning and transport system,

C) analysis system,

D) automatic calibration system,

E) acquisition and processing system.

Essential for a reliable analysis system? that the sample taken in the correct and representative quantity arrives compositionally intact to the analysis system.

All of this? having said, without prejudice to the concept of minimizing interventions for both periodic and extraordinary maintenance and to allow availability? to exercise for longer times? as long as possible, the analysis system provided has the following characteristics.

A. The sampling? carried out with a probe, with an easily inspectable and heated filter, whose sinking? calculated according to the dimensions of the duct and the specific speeds.

The sample taken? transported at a temperature above the dew point in order to avoid dangerous condensation and centesimal variations of the components.

B. Does the conditioning of the sample have the specific function of eliminating the condensable part of humidity? taking care that the quantities are not eliminated? of some gases that are soluble in water. This effect can? be validly achieved, with an excellent degree of precision, using a physical process with very rapid temperature lowering and minimizing the time and the contact surface of the sample gas with the condensate.

C. The analyzes are performed by a series of high resolution and precision analyzers. The analysis of HCI? carried out hot (therefore, before the sample conditioning operations, as described above). The system used for the analysis of these gases? based on the absorption of infrared radiation with a non-dispersive method.

D. The calibration system foresees to intervene only for the time necessary to change the cylinders containing the gases of known concentration and also this operation takes place upon precise signaling of the system itself.

E. The processing and calculation system allows to process all the information received from the analyzers and the calibration system in order to produce semi-hourly, hourly and daily tables with formatting of the data in definable classes.

Said system can? be used in order to obtain a monitoring and data acquisition system based on a PC with graphic video and printer for viewing on histograms or in unit? engineering and the recording in historical archives of the analog data (presumably a number of about 80) coming from the process.

The software programs should allow supervision on video pages referring to the main parts of the system, online visualization of main data, reporting and printing of alarm data.

Computerized control, command and management systems

The control and regulation system? divided into substations composed of an electromechanical control panel 19 in which the auxiliary? replaced by software-controlled switching cards and programmers designed for process control.

Without prejudice to both the conception and the structuring of the various lines making up the treatment plant, the proposed system allows both the automation and the most? complete the various processes and their optimal and safe management.

The waste-to-energy plant includes the following main control and safety lines:

main burner and post-combustion burner regulation systems;

temperature regulation system in the context of primary combustion;

temperature control and regulation system in the post-combustion chamber;

free oxygen measurement system and regulation of the same at the exit of the post-combustion chamber cos? as control and regulation of the operation of the relative regulation dampers;

system for measuring and recording oxygen, temperature, pressure, humidity, dust, hydrochloric acid, Sox, Nox, COT on the flue exhaust pipe downstream of the flue gas purification system as per specification;

temperature and pressure control system on the inlet duct to the bag filter and control of the fume / air exchanger fan with emergency chimney control.

The temperature and free oxygen control systems in the fumes leaving the post-combustion chamber are directly connected to devices 1 and 2.

Device 1: temperature control: modulates the flow of support fuel (diesel oil) to the modulating burner of the primary combustion chamber, as well as? of the engine connected to the dampers placed on the combustion air supply ducts. The system ? Furthermore, it is connected and controls the motor of the waste feeding screw in order to block the feeding in case of non-respect of the set conditions.

Device 2: free oxygen control: modulates and regulates the dampers placed on the excess air supply lines in the post-combustion chamber, in order to guarantee the minimum content of 6% by volume in the fumes leaving it. How about the temperature control system, this system? connected and controls the motor of the solid waste feeding screw in order to block the feeding in case of non respect of the set conditions.

? a post-combustion chamber is also provided, the operating parameters of which are as follows:

free 02 content in the fumes (measured at the chamber exit)> 6% by volume;

speed gas mean (in the inlet section)> 10 m / s; smoke residence time> 2 seconds;

smoke temperature> 950? C.

The plant? able to maintain a combustion efficiency in the foreseen operating conditions, understood as the CO2 / (CO2 CO) ratio higher than 0,999 and? equipped with instrumentation for continuous automatic control of the main project parameters.

With regard to emissions into the atmosphere, does the plant guarantee compliance with the emission standards in force in the countries in which it will come? installed.

The waste that decays from the waste-to-energy system consists of:

solid decaying from the rotating drum consisting of slag and inert bottom ash, quantifiable in about 670 Kg / h;

dusty solid decaying from the post-combustion chamber consisting of inert bottom ash, quantifiable in about 3 kg / h;

powdery solid decaying from the bag filter consisting of salts and metal oxides, quantifiable in about 110 Kg / h;

aqueous solution no more? recyclable which is periodically given outside, quantifiable in about 2 cubic meters / day.

Technical measures to comply with the requirements on emissions and immissions

1. The primary incineration stage? followed by a post-combustion system. A fully automated regulation system linked to free oxygen control? in charge of controlling the secondary combustion air supply in order to guarantee a minimum value of free oxygen at the outlet of 6%. The particular shape of the post-combustion chamber guarantees a particularly long flow path of the gases to be treated with a minimum residence time of 2 sec. An automatic regulation burner maintains the operating temperature of 1200? C. This temperature? continuously monitored and recorded. In this way, the complete combustion of organic compounds present in the fumes is guaranteed.

2. The particular loading system referred to? equipped with the rotary kiln with the combination of loading hopper and mixing and dosing screw, it allows to obtain a continuous feeding and at the same time to mix different types of waste according to the consistency and combustion characteristics in order to take into account the connected problems with regulation of the fumes treatment system. It is therefore not possible to feed more? combustible material to the furnace than is allowed by the control instrumentation. The feeding auger with continuous and proportional regulation, used in this case, allows instead to dose the material to be treated in the rotary kiln with remarkable precision.

3. The following fundamental parameters are controlled and guaranteed by the plant's control and regulation system, regardless of the general automation and specific operating functions:

Loading auger:

Guide value controlled: = T fumes in post-combustion.

Inserted auger: = T greater than 950? C

Auger off: = T less than 900? C

Post-combustion chamber support burner:

Guided value controlled: = T fumes at post-combustion outlet.

= 02 post-comb.

Burner insertion: = T <of 950-1200? C

Burner at minimum: = T> of 950-1250? C

Rotary oven support burner:

Guide value controlled: = T fumes in post-combustion.

Burner insertion: = lower T 800? C

Burner at minimum: = T greater than 900? C

4. The computerized control unit provides, in addition to the instant indication and display, also to the recording of all the operating phases of the system with the possibility? of printing.

The following data is recorded periodically:

Post-combustor entry T: 950? 1050? C

Post-burner output T: 950? C? 1200? C

Vacuum in the reaction chamber: -5 mm c. H2O

Free O2 in post-combustion outlet:> 6%

The components of the supply are as follows.

Position n. 1: loading system for rotary kiln complete with:

vibrating screen with inclined plane;

conveyor belt;

weighing belt on the infeed;

shredder;

loading hopper in sturdy steel carpentry directly coupled with the screw and supported by a steel trellis (useful capacity: 5 m <3>);

Large diameter auger in special steel and refractory steel for the part in contact with the fumes, with a single housing for the shaft on the drive side, for continuous loading of the furnace.

Indicative dimensions:

screw diameter about 500 mm;

auger length about 2,000 mm;

maximum capacity 7 t / h;

installed power 5.5 Kw.

The cochlea? complete with parallel shaft gearmotor, alternating current motor powered by frequency converter.

The guide cylinder of the auger, inside the furnace,? lined with ceramic refractory.

The auger shaft has only one slot on the loading side.

Position n. 2: D200 rotary kiln

Counter-current fed (basic version), consisting of: cylindrical shell in welded sheet metal complete with steel raceway;

groups of rollers for rolling and axial guiding of the cylinder; traction system, parallel shaft gearmotor with three-phase direct current electric motor powered by frequency converter.

Special block insulation of the intermediate jacket.

The interior lining of the oven? made of special steel plates arranged like scales, anchored to the outer shell, easily interchangeable.

Slag unloading system on the kiln exits designed to avoid the introduction of dust into the environment during the unloading phases; said system? directly coupled to the head wall of the oven.

A head also includes the support structure for the burner and relative lance.

Trailer for the D200 oven, fully assembled with the necessary accessories.

Position n. 3: with reference numbers 10 and 11? a combined diesel - liquid waste combustion system with compressed air atomisation is indicated.

The system includes a modulating regulation burner with a high modulation ratio.

The burner? equipped with:

UV flame control,

servo-assisted regulation valves for combustion air and excess air controlled by temperature regulation system, pilot gas burner with ignition electrodes and ionisation flame control,

UL-type compressed air atomisation lances for liquid waste injection.

The system also includes a fan for combustion air for solid waste and a fan for combustion air for the burner.

Position n. 4: post-combustion system.

In vertical and horizontal execution, designed for an operating temperature of 950? C - 1,200? C. Design temperature 1,400 ° C.

Made of sturdy steel carpentry and internally lined with refractory thickness 230 mm almost? insensitive to thermal shock and with very high resilience.

The post-combustion system? mounted on two sections.

The two sections are transported on two trailers in a horizontal position. The chamber is positioned vertically, with the use of a crane, on the installation site. The second chamber, on the other hand, remains in a horizontal position.

The combustion air is introduced through a circular chamber concentric to the reaction chamber, whereby it preheats while cooling the supporting structure of the reaction chamber at the same time.

Which combustion system? a cyclonic burner of the "combustor" type is provided, which guarantees excellent mixing of the components competing in the combustion reaction.

Dwell time> = 2 seconds. External temperature of the carpentry 150? C with internal temperature d? 1,200? C.

The gas inlet section to be treated? sized to obtain a speed? flow rate of 10 m / sec.

The equipment includes a D300 post-combustion chamber with combustor, a normalized trailer for D300, assembled with all the support structures and anchors, and coupling systems for the crane.

- Pivoted and rotating frame for vertical positioning with the use of autogr?

-Removable support structures

-safety seat.

The equipment includes a D310 post-combustion chamber, an emergency chimney with closing system, mounted on the post-combustion chamber, with rapid opening with pneumatic actuator control, an automatic closing system for emergency chimney, opens in no current, a normalized trailer, fully assembled with all the support and anchoring structures.

Position n. 5: boiler

The fumes coming from the post-combustion chamber have a temperature of about 1,200? C and are cooled through the air / air exchanger and an air / air energy recovery boiler.

Position n. 6: fumes treatment section

The section includes a reagent dosing system, dedusting and dry flue gas treatment, for the separation of HCl, HF and SOX.

The treatment of dry fumes? carried out in the C600 reactor with the dosage of a mixture of calcium hydrate with activated carbon as adsorbents.

The product of the mixture? separated from the gas flow together with the dust present in the F600 filter.

The reactor, the filter, the pneumatic transport system, the fan and the silo for the adsorbent material are mounted on a single trailer.

The system includes:

a) reactor for absorption made of St 37, including the necessary accessories, such as deflectors and flow orientators, turbulators and inspection doors,

b) filter (with a Goretex filter medium or similar),

c) storage and additive dosing system, consisting of: lime silo capacity? 10 m <3>, including ladders, railings; level control system; breather pipe; shutter; fluidization system; rotocella; lime transport fan; injection point; connecting pipe;

auger installed in the dust collection hopper; rotocella for dust extraction;

silo for reagents of about 10 m <3>;

normalized trailer for the dry smoke treatment system, assembled with all the support and anchoring structures;

d) control and power panel.

Wet fume treatment plant

The wet fume treatment plant? consisting of a cross-flow washer in horizontal execution with a C700 quench at the inlet, a first acid wash phase with PH C710 adjustment, a second neutralization or slightly acid wash phase with PH C720 adjustment and an F700 droplet separator .

All internal parts can be disassembled through the manholes.

The plant includes:

quench, with all the necessary connections for gas, water, emergency water, tangential washing of walls;

two-stage filling column with two separate washing water circulation systems;

droplet separator;

radial pumps for quenching with the washer complete with shaft seal (Si / SiC) coupling, coupling protection, base and electric motor;

radial pumps for the washer.

Connection pipes and pipes for washing solutions: GFK / PP

Position n. 7: fans.

Position n. 8: final expulsion chimney

The chimney, from where the fumes are released into the atmosphere, is the only point of emission of the waste-to-energy system.

Fireplace ? also equipped with:

inspection hatch;

external marine staircase up to a height of about 10 m with relative protection cage;

platform set up to allow access to emission sampling systems for the required analytical checks; continuous detection, analysis and recording system of the concentration of the following pollutants: dust, hydrochloric acid, nitrogen oxide, total organic carbon, sulfur oxide;

? also foreseen the continuous detection of temperature, humidity, pressure, speed;

? finally, the detection and recording of temperature and oxygen in the fumes is envisaged in order to have an immediate reference parameter for verifying compliance with the authorization requirements.

Fireplace ? constituted in two trunks and? self-supporting.

Position n. 9: connection pipes, complete with flanges, inspection doors, logs for measurements, lining in refractory materials for temperatures above 500 ° C, pipe from fan to quench, pipe from fan for treated gas, ebonite, pipe to chimney for gas post heated to 150? C, compensators on the pipes.

Position n. 10: control and regulation panel

The control panel 19 includes, among other things:

adjustment systems for the burner, the rotary kiln and the post-combustion burner;

temperature regulation system in the field of primary combustion - solids;

temperature regulation system in the context of primary combustion - liquids;

temperature control and regulation system in the post-combustion chamber;

temperature control and regulation system in the thermal recovery and filtration phases;

free oxygen measurement system and regulation of the same at the exit from the post-combustion chamber;

system for recording temperature and oxygen measurements.

In the painting ? also contained all the power for the various machines installed, cos? like all the safety measures prescribed by the DIN 4754 standard.

Position n. 11: generator and compressor

Generator with diesel engine for the supply of 100% of the energy necessary for the operation of the mobile system.

Position n. 12: power supply systems

Feeding system for diesel, liquid waste, compressed air and water so? as collection and disposal of waste water.

Position n. 13: transport and assembly

The trailers are supplied with the dimensions indicated.

Parts such as piping, compensators, chimney, so on? such as containers for ashes and reaction products, tanks for diesel and liquid waste, etc., are transported on normal trucks. For this purpose, the cost of a dedicated trailer does not appear to be justified.

For the storage of small pipes, spare parts and various equipment? a 40 FT container is foreseen.

Functional logic, solid waste incineration and post-combustion section

The start-up procedure includes:

1: starting the combustion air supply and excess fans of the rotary kiln and of the combustion station;

2: start-up of general system suction fans; the capacity of the fans? in this phase to the minimum, as the valves that control the flow are closed, or why? the regulators that command them keep them to a minimum, or why? the starting logic foresees that this is the case;

3: rotary oven rotation start;

4: post-combustion chamber burner starting;

5: rotary oven support burner starting.

Before placing the solid waste in the oven, the following conditions must be met:

post-combustion chamber temperature at steady state conditions (950 ° C);

rotary kiln outlet fumes temperature> 800 ° C or, in any case, a temperature sufficient to allow the immediate ignition of solid waste combustion.

Solid waste feeding at the beginning? manually adjusted, as the regulation logic would immediately bring the maximum speed? of the cochlea.

Only after manually reaching the speed? desired loading,? waste flow rate regulation converted to automatic.

Exercise

Rotary oven outlet fumes temperature

It is regulated within a range between a max. and min. within which? maintained by the simultaneous action of two regulators.

One regulator acts on the support burner aimed at maintaining the temperature at the minimum value of the band, while the other regulator acts on the waste loading screw, decreasing its speed. proportionally to the temperature increase until it is completely canceled when the maximum value of the operating band is reached. A further increase in temperature causes, at a predetermined value, the shutdown also of the support burner which in the meantime had reached the minimum potential. .

The lowering of the temperature of the fumes to a minimum established value, despite that the support burner is working at maximum potential, causes the waste feeding screw to stop, since? this means that the operating conditions of the plant are completely different from the theoretical ones for which the operating parameters have been previously set (caloric value of the waste, waste flow rate, residual O2, excess air) and? therefore it is necessary to intervene by the operator to verify the causes.

Combustion air from the rotary kiln is regulated by controlling and regulating the residual oxygen in the fumes at the outlet of the rotary kiln (stilling chamber).

This adjustment acts on the flow rate of the air introduced into the rotary through the head. The desired set point value? established as a function of the excess air foreseen by the theoretical energy-mass balance.

Assumed from the experience that the excess combustion air is optimal for rotary kilns? 2 to 2.4 times the stoichiometric one, the resulting residual oxygen? roughly variable between 9.5 and 11.5%.

Despite the regulation of the air, the predictable extreme heterogeneity? solid waste will cause? also strong fluctuations of residual O2. This consideration must serve to foresee sufficiently high excesses of air to minimize the possibility? excessive lowering of residual oxygen. For this reason, minimum and maximum residual O2% alarm thresholds are envisaged, the achievement of which does not cause automatic interventions in the operating logic, but are used by the service personnel to assess any need? to vary the set point of the residual oxygen regulator.

The combustion air flow is regulated, as seen by the residual oxygen regulator in the fumes after the rotary. This flow rate is also read directly by a flow meter with a calibrated flange as its value d? indirectly the instantaneous operating duty of the plant. Also in this case there are minimum and maximum alarm thresholds, the intervention of which? indicates that the plant is operating outside the expected operating range.

Maximum combustion air flow pu? be caused by:

waste rate too high;

caloric value of waste greater than expected;

set point% O2 residual set on the regulator too high minimum combustion air flow pu? be caused by reasons contrary to the above.

Rotary oven depression

The rotary kiln and subsequent stilling chamber must be kept under constant negative pressure. This condition is ensured by a differential pressure control with respect to the atmospheric one, which varies the flow rate of the general system fans according to the pressure existing in the stilling chamber.

As described above, the plant, in particular the primary combustion section (rotary kiln), works in transient conditions that the regulation systems tend to maintain within a predetermined range. This transience? it also reflects on the depression conditions of the oven, therefore? the elements that make up the regulation chain (instruments, valves, set point, integral time, etc.) must be established in an appropriate way to ensure that the oscillations that occur during operation are always in the negative range.

Here, too, high and low depression alarm thresholds signal the departure from normal operating conditions. The low depression threshold in particular causes the feeding screw to stop, while the high depression threshold simply causes a recall signal for the operator in order to verify the causes.

Post-combustion smoke temperature

The temperature of the fumes coming from the rotary kiln has a variable trend influenced by the heterogeneity? some waste. The regulation must take this fact into account and therefore have the characteristic elements (proportional band, integral time and derivative) suitable for allowing an extremely fast response action.

The post-combustion temperature has three alarm thresholds: one for minimum and two for maximum.

The minimum threshold causes the waste feeding screw to stop. The first maximum threshold provides for a simple alarm d? signaling to the service operator while the second threshold causes the waste loading to stop, the modulation to the minimum of the burner supporting the rotary kiln and the maximum opening of the residual oxygen regulation valve at the post-combustion outlet.

If the temperature does not drop below this threshold within a certain time, the burners supporting the rotary kiln and the post-combustion chamber also stop.

Residual oxygen in the fumes at the post-combustion outlet The fumes from primary combustion have a percentage of residual oxygen between 9.5 and 11.5% as a result of the large excess of air necessary to ensure good combustion in the rotary kiln. The combustion air of the support burner will come? regulated with an excess depending on the type of fuel used, variable between 1.1 and 1.3.

Therefore, the post-combustion products, in a sufficiently stable regime, will have a resulting oxygen rate certainly above the 6% required by law. The regulation of residual oxygen? in any case necessary to avoid possible drops below the minimum threshold that can occur during operating transients.

The intake of this excess air is carried out through an inlet or more? additional entrances to the post-combustion chamber. The residual oxygen percentage has two minimum alarm thresholds.

The first threshold stops the waste feeding screw. This action will not necessarily stop. immediately the descent curve of the residual oxygen, as the waste already? present in the rotary kiln still burn for about half an hour.

If the decrease reaches the second threshold, the combustion air regulation valve in the rotary kiln automatically moves to a predetermined opening value.

Stop operations

The first operation? the stop of the waste feeding screw

This operation causes, not immediately but progressively as the combustion of the waste remaining in the furnace ends, the modulation of the combustion air flow in the rotary machine to a minimum. Section d? corresponding post-combustion leads to conditions, if not of minimum, of reduced load. The support burner of the rotary kiln could, on the other hand, tend to increase its load in relation to the fact that, progressively ceasing the caloric intake from the waste, the combustion air in the rotary remains, albeit at a minimum. At this point it is necessary to lower the flow rate of this air to a "minimum stop cycle" pi? low operating minimum.

The second operation? the stop of the burner supporting the rotary kiln when it is considered that the combustion of the waste is certainly exhausted.

The third operation? the stop of the burner supporting the post-combustion chamber.

Finally, the components of the system are allowed to cool, taking care that the speed? cooling temperature is not too high, otherwise the flow rate of the fans that introduce air into the system is reduced. In this regard, the experience of exercise on the plant could also suggest the possibility? to stop one or all of the fans as long as the section remains in depression and that localized overheating does not occur which could damage system components.

Yup ? in practice it has been observed that the invention achieves the intended aim and objects by having provided a waste treatment plant characterized by total mobility.

The plant? designed and sized with the maximum degree of assembly and in such a way as to be installed directly on wheeled semi-trailers, suitable for free road transport. The engineering of the plant according to the invention further provides that it can be installed without accessory infrastructures.

The criterion of "mobility" does it include transportability? of the plant on various types of roads and various other advantages such as, adaptability? of the plant to different types, conformations and characteristics of the ground, the maximization of engineering, to have materials connected to the transfer of the plant from one site to another and to the commissioning on the new site, the wide operating range.

Indeed the plant? was designed to work without infrastructures such as warehouses and can? operate in different climatic conditions, from -40 ° C to 40 ° C outside temperature.

An added benefit? consisting of the minimization of disassembly and reassembly times, which are in turn a function of factors such as weights, dimensions and complexity? installation; in the sizing of the various equipment and components and in the definition of their assembly, all the design and functional solutions were adopted aimed at minimizing the economic costs and time necessary for the installation, uninstallation and transfer phases.

Special care? It has also been placed in the selection of refractory and insulating materials, which are suitable for withstanding the problems associated with thermal shocks resulting from the discontinuous operation of the plant.

Furthermore, in order to facilitate the transfer operations of the unit, the refractory material? of considerably reduced thickness and covered with steel plates, arranged in scales, designed to limit the weight of the equipment and prevent damage to the refractory.

The plant according to the invention? susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept; furthermore, all the details can be replaced by technically equivalent elements.

Of course the materials used, as well as? the dimensions may be any according to the requirements and the state of the art.

Claims (5)

CLAIMS 1. Mobile waste treatment plant characterized by the fact of including a plurality of of functional components arranged on rubberized means. 2. Plant according to claim 1, characterized in that each of said means? normalized and in shape, allowing a movement on the road, without the need? spare. 3. Plant according to claim 1, characterized in that each of said rubberized means? consisting of a semi-trailer. 4. Plant, according to claim 1, characterized in that said functional components comprise one or more? between the following means: a rotary drum kiln, a first chamber section d? post-combustion, a second section of post-combustion chamber, an air / fume exchanger, a boiler, a dry fume treatment plant, a wet fume treatment plant, a control room and distributed control and pollutant monitoring systems, a generator and general plant services. 5. Plant, according to one or more? of the preceding claims, characterized by the fact of functioning autonomously without benefiting from external services.