Abstract:
The method and equipment are intended for application in the chemical industry for destruction off solid substances, containing carbon and hydrocarbons. The invention guarantees absence of oxygen in the reactor and permits increased thermal efficiency. The closed forehearth is used to preheat every tyre that follows. The technologic comfort is due of use of spark proof material for the internal space of the forehearth; off the use water-cooled rollers ( 22 ) sealed in a casing ( 23 ), placed under the cylindrical reactor ( 1 ) and into a water pool ( 24 ), forming a back-pressure gate and of the use of three independent band conveyors, forming an discharge transport system.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention refers to method and equipment for whole tyre pyrolysis intended for application in the chemical industry for thermal destruction of solid substances, containing carbon and hydrocarbons aiming at their decomposition to liquid hydrocarbon fractions obtained after condensation in a concurrent process, solid carbon and hydrocarbon combustible gases. 
       BACKGROUND OF THE INVENTION 
       [0002]    A method of pyrolysis of whole tyres is known in the art accomplished by indirect heating thermal processing and significant gastightness. The gaseous products realized during the heating are conducted and rectified in a concurrent continuous process, and the different solid substances are taken out. Before its admission to the thermal processing zone every tyre passes through an oil bath, and during its further progress to the upper part of the thermal processing zone it is drained, dried and heated. The disadvantages of this method are that part of the oil in the bath is taken with each subsequent tyre, it is not fully drained and penetrates the zone of thermal treatment with oil residues, which leads to additional energy costs for pyrolysis of the oil too. In fact there is no preheating of the tyres because the heat is used to warm the oil film that covers the tyres. There is no guarantee that there would be no additional oxygen flow as a result of the tyres passing through the oil bath, which is absolutely undesirable, because it interferes the process. [1] 
         [0003]    Equipment for whole tyre pyrolysis is also known in the art, comprising a vertical cylindrical reactor with heating combustion system and feeding transport system positioned horizontally at the upper level of the reactor. There is an output conveying transport system under the reactor. There are pipelines in the upper part of the reactor, connected to its inner chamber to take out the gaseous products realized, the same being additionally processed into a condensation separation system connected to the equipment. The combustion system comprises combustion chamber, embraces the whole height of the reactor, and burners placed symmetrically around the reactor in the lower part of the combustion chamber. There is a circular channel in the upper part of the combustion chamber, taking out the exhaust gases. The feeding transport system is made of subsequently installed feeding roller conveyor and chambers. The chambers are three and are separated by overhead valves. The first chamber is a receiving one, open and is a continuation of the roller conveyor. The second chamber is a forehearth, separated from the other two by overhead valves and is provided of two gas pipes for supply of part of the exhaust gases from the combustion chamber and for inert gas supply. The third chamber is located above the reactor and covers its lid. The receiving chamber and the forehearth are provided of pneumatic cylinders for advancing the tyre that follows. The discharge conveyor system comprises pairs of watercooled shafts enclosed into a casing, connected with its upper part to the lower part of the reactor. The lower part of the casing is sunk into a water pool where a discharge conveyor is placed with its edges elevated over the water level. A shortcoming of this whole tyre pyrolysis equipment is that the feeding transport system has three chambers, the receiving chamber being separated by the other two chambers next only by overhead valves, which substantially reduces the heat efficiency of the equipment. The substantial problem with the overhead valves is the unreliable closing and gastightening of the chambers, as well as the impossibility to reduce the pressure therein. Another problem of the overhead valves is also the possibility to infiltrate oxygen in the reactor, which is completely undesirable. One of the most important conditions for conducting a pyrolysis process is the organic substances thermal destruction wherein the complex hydrocarbons shall be decomposed into simple in the absence of oxygen to prevent their burning. 
         [0004]    At the same time the lid of the reactor and the walls of the third chamber are not thermally insulated which leads to a significant drop of the thermal efficiency of the equipment. The conveying of the solid products with a large reversing conveyor into the bath of the hydraulic back-pressure gate of the conveying transport system is a source of technological problems during the operation of the equipment. [2] 
       SUMMARY OF THE INVENTION 
       [0005]    The objective of the invention is to create a method an equipment for pyrolysis of whole tyres by achieving a better thermal efficiency and high reliability, guaranteeing that no oxygen shall penetrate in the reactor of the equipment, and especially in the area of thermal processing under indirect heating. 
         [0006]    This task is achieved by a method of whole tyre pyrolysis accomplished with thermal processing by indirect heating and substantial gastightness. The gaseous hydrocarbons realized during the heating are conveyed and rectified into a continuous concurrent process that takes place into a condensation separation installation with discharge of the solid components. Before being fed into the thermal processing area every tyre is preheated, and according to the invention, a separate space is determined for its preheating apart from the area of thermal processing and the environment, the space being vacuum treated and filled with inert gas. 
         [0007]    Another feature is that when applying the whole tyre pyrolysis method the preheating of each tyre is made directly from the area of thermal treatment. 
         [0008]    It is suggested that when applying the method of whole tyre pyrolysis the tyres shall remain in the preheating space for a period of 15 to 60 seconds. 
         [0009]    The task is solved with an equipment for whole tyre pyrolysis comprising a vertically positioned cylindrical reactor heated by a combustion system. Horizontally, at the reactor&#39;s upper level is placed a feeding conveyor system. There is a discharge conveyor system under the reactor. In the upper part of the reactor there are pipelines connected to its internal part intended to discharge the gaseous products realized in the reactor. These gaseous products are conducted to a condensation separation installation connected to the equipment. The combustion system comprises a combustion chamber embraces the reactor along its height and burners symmetrically placed in the lower part of the combustion chamber. There is a pipeline in the upper part of the combustion chamber intended to discharge the exhaust gases. Successively installed supply roller conveyor and chambers form a feeding conveyor system. The chambers according to the invention are two. The first is horizontally oriented, open receiving chamber, connected to the supply roller conveyor, and the second is also horizontal, partially covering the reactor and the hermetically closing forehearth. There is a vertical valve between both chambers with lifting and hermetically sealing mechanisms. The walls of the forehearth in the first section placed over the cylindrical reactor are double and water-cooled. They have a horizontal duct for vacuum treatment and a inlet for inert gas supply. The inner surface of the forehearth is covered with spark proof material. The discharge conveyor system consists of the band conveyors one of them being a horizontal reversing conveyor ( 25 ), and the other two being left ( 26 ) and right ( 27 ) sloping discharge conveyors. 
         [0010]    According to a preferred embodiment, the hermetically closed forehearth_has two sections, the first one located just over the cylindrical reactor, covering its whole lid, tightly attached with its lower part to the reactor, and the second section is connected to the receiving chamber and is its continuation. At the inlet of the forehearth second section there is a vertical valve provided of vertical pneumatic cylinders for opening and horizontal pneumatic cylinders for hermetic sealing. 
         [0011]    It is advisable to provide the hermetically closing vertical valve of a pair of pneumatic cylinders for opening and two pairs of horizontal pneumatic cylinders for hermetic sealing. 
         [0012]    Furthermore, pushing pneumatic cylinders are provided for supplying the whole tyres from the receiving chamber to the forehearth and from the forehearth_to the reactor. 
         [0013]    Preferably, the receiving chamber shall have one first pushing pneumatic cylinder, installed outside the receiving chamber between guides, oriented perpendicularly to the course that the tyres follow to be fed in. 
         [0014]    Preferably the forehearth shall have also a pair of external second feeding pneumatic cylinders with a pushing rod placed between them and connected to them pushing the successive tyre, the pushing rod being hermetically sealed to the respective wall of the forehearth. 
         [0015]    It is also advisable that the lid of the reactor, located in the water cooled walls section of the forehearth shall be connected to a lifter installed between two third lifting pneumatic cylinders, vertically attached to the external upper part of the forehearth over the cylindrical reactor. 
         [0016]    It is also suitable that the pipelines for the gaseous products realized in the cylindrical reactors shall be horizontal, radially arranged channels. 
         [0017]    Besides, according to a preferred embodiment of the invention, the feeding roller conveyor shall be comprised of two parts, one being freely rotational and the other force driven. 
         [0018]    According to another preferred embodiment, the conveying transport system is composed of at least one pair of water-cooled rollers with three band conveyors placed beneath. The pair of rollers is tightly sealed in a casing under the reactor, the upper part of the casing being attached to the bottom of the reactor, which is opened, and the bottom part of the casing is placed in a water pool. Thus a water back-pressure gate is formed for the cylindrical reactor and it is environmentally isolated from beneath. 
         [0019]    It is also advisable the burners in the combustion chamber of the combustion system to be placed tangentially. 
         [0020]    The method of whole tyre pyrolysis achieves a guaranteed absence of oxygen in the reactor thanks to the fact that before the tyres are fed in the reactor, they are vacuum treated in the separate space, and then, still with the corresponding tyre in, it is filled with inert gas. 
         [0021]    With the equipment of whole tyre pyrolysis is achieved an integral technologic structure where the number of the chambers of the feeding system is reduced to two with an increased thermal efficiency thanks to the thermal insulation of the reactor&#39;s lid. The residual heat in the hermetically closed forehearth is used to preheat the tyre that follows. The reliable and tight sealing of the forehearth guarantees that no oxygen will penetrate in the reactor. An additional advantage of the equipment is the use of spark proof material for the external insulation of the forehearth. At the same time, the use of three independent band conveyors in the solid discharge transport system provides technologic comfort and increases the reliability of the equipment. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0022]      FIG. 1  is a transverse section of the equipment for pyrolysis of whole tyres; 
           [0023]      FIG. 2  is a top view of the feeding conveyor system; 
           [0024]      FIG. 3  is a front view along A of  FIG. 2  of the feeding conveyors system; 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0025]    The method of whole tyre pyrolysis is accomplished with thermal treatment by indirect heating at substantial gastightness. The gaseous hydrocarbons realized are carried to a condensation separation installation connected to the equipment where they are rectified in a continuous concurrent process. The separated solids are taken out, and every tyre is preheated before being dropped into the thermal processing area. Prior to the preheating of the subsequent tyre, the space where it occupies is vacuum treated and is filled with inert gas. This space is separated from the area of thermal treatment. The preheating of each subsequent tyre is made directly from the area of thermal processing for 15 to 60 seconds depending on how intensive the industrial process is. 
         [0026]    The equipment of whole tyre pyrolysis according to the invention comprises a vertically positioned cylindrical reactor  1  provided of a combustion system for heating, consisting of a combustion chamber  2  that embraces the reactor  1  along its height, and burner  3  surrounding symmetrically the reactor  1  in the lower part of the combustion chamber  2 . They are of a known type and could be of individual adjustment. Besides the burners  3  are tangentially situated around the cylindrical reactor  1 . Horizontal, radially arranged channels  4  are located in the upper part of the cylindrical reactor  1 , the pipelines  4  being connected to the inner space of the reactor to convey the gaseous products to the concurrent condensation separation installation (not shown on the figures attached). Horizontally, at the upper level of the cylindrical reactor  1  is located the feeding conveyor system, comprising a supply roller conveyor  5  that has a freely rotating and force driven sections, and two chambers. The first one is horizontally oriented open receiving chamber  6  that is a continuation of the supply roller conveyor  5 . The second is a forehearth  7  and is also horizontal as a continuation of the receiving chamber  6 . Forehearth  7  is closing hermetically by means of a vertical valve  8  dividing both chambers  6  and  7 . The forehearth  7  has a first section  9 , located just above the cylindrical reactor  1 . The first section  9  embraces the lid  10  of the cylindrical reactor  1  with its upper part, and its lower part is tightly attached to the cylindrical reactor  1 . The forehearth  7  has also a second section  11  that is connected to the receiving chamber  6  and is its continuation. At the inlet of the forehearth  7  a hermetically closing vertical valve  8  is mounted. For the reliable operation of the vertical valve  8  it is provided of a pair of vertical pneumatic cylinders  12  for opening, and two pairs of horizontal pneumatic cylinders  13  for gastight sealing. The walls of the forehearth  7  in the first section  9  mounted over the cylindrical reactor  1  are double and water-cooled, and they have horizontal ducts  14  and inlets  15  for vacuum treatment and for the provision of inert gas after the subsequent tyre is let in the forehearth  7 , respectively. The first pushing pneumatic cylinder  16  is installed outside the receiving chamber  6  between guides  17 . The pushing pneumatic cylinder  16  and the guides  17  are perpendicular to the course the tyres follow during their transportation by supply roller conveyor  5 . The forehearth  7  has two external pairs of second feeding pneumatic cylinders  18  with a pushing rod  19  placed between them and connected to them, the pushing rod  19  being hermetically sealed to the respective wall of the forehearth  7 . The inner walls of the forehearth  7  are covered with spark proof material. The lid  10  of the cylindrical reactor  1 , located in the first sector  9  with watercooled walls of the forehearth  7  is connected to a lifter  20  installed between two third lifting pneumatic cylinders  21 , connected vertically from outside the forehearth  7  over the cylindrical reactor  1 . The equipment has also a conveying transport system consisting of at least one pair of water-cooled rollers  22  with three band conveyors placed beneath. The pair of the water-cooled rollers  22  is tightly sealed in a casing  23  attached to and under the cylindrical reactor  1  which is open, and the lower part of the casing  23  is placed into a water pool  24 . Thus a water back-pressure gate of the reaction space of the cylindrical reactor  1  is formed. One of the band conveyors is a horizontal reversing conveyor  25 , and the other two are left  26  and right  27  sloping discharge conveyors, respectively. They are provided, respectively, for conveying the whole tyres at the beginning of the process until the regular operation in the reaction unit starts, and to discharge the solids—carbon and steel wire during the regular operation. 
       APPLICATION OF THE INVENTION 
       [0027]    The equipment for whole tyre pyrolysis operates as described bellow. 
         [0028]    The cylindrical reactor  1  is heated by the combustion system, respectively, by the tangentially positioned burners  3  of the combustion chamber  2 . Simultaneously, the supply roller conveyor  5  feeds the subsequent whole tyre to the receiving chamber  6 . During this time interval, the receiving chamber  6  is separated from the forehearth  7  by a vertical valve  8 . In this instant the two pairs of horizontal pneumatic cylinders  13  close hermetically the vertical valve  8 . The lid  10  of the cylindrical reactor  1  is also closed. The vertical valve  8  is lifted by pair of vertical pneumatic cylinders  12  while the action of the two pairs of horizontal pneumatic cylinders  13  is stopped. The subsequent tyre is supplied in the second section  11  of the forehearth  7  by the first pushing pneumatic cylinder  16 . It is externally mounted on the receiving chamber  6  between the guides  17 . After the passing of the subsequent tyre through the place of the vertical valve  8  it is hermetically closed by the horizontal pneumatic cylinders  13  while the pair of vertical pneumatic cylinders  12  releases the vertical valve  8 . After this the forehearth  7  is vacuum treated through the horizontal duct  14  and inert gas is supply in it through the horizontal inlet  15 . The subsequent tyre remains between 15 and 60 seconds (depending on how intensive the process is) in the forehearth  7 , a time for which it absorbs residual heat from the previous cycle. Then the lid  10  of the cylindrical reactor  1  is lifted with the externally mounted lifter  20 , attached to the lid  10  and forwarded with the aid of the two third lifting pneumatic cylinders  21 . The tyre receives a new portion of heat and is simultaneously driven to the opening of the cylindrical reactor  1  with the pair of second feeding pneumatic cylinders  18  and the pushing rod  19  connected to them. The process is carried out with uninterrupted feeding of whole tyres at a determined rate and with a constant release of gaseous hydrocarbons, being conducted through the horizontal radially arranged channels  4  to the condensation separation installation, connected to the equipment and operating as a sole unit with it. This unit traditionally comprises a centrifugal cyclone for dust arrest and separation of the heavy liquid fractions, two scrubbers backfilled and sprinkling for successive separation of the heavy cut and the float fraction, and tubular water cooler for the float fractions, all of them not shown on the figures attached. After the gaseous products are released through the bottom opening of the cylindrical reactor  1 , the solids—carbon and steel wire—are conveyed by a pair of water-cooled rollers  22  through the casing  23  in the water pool  24  falling over the horizontal reversing conveyor  25  and by the right sloping discharge conveyor  27  are discharged into equipments for further processing. The other sloping discharge conveyor  26  is provided at the beginning of the pyrolysis when the tyres pass whole through the cylindrical reactor  1  until the area of thermal processing enters into a regular temperature cycle for carrying out a continuous pyrolysis. 
       REFERENCES 
       [0000]    
       
         1. German Patent Application 2404800 
         2. European Patent Application 03472003