DOUBLE-FUELLED TUBELESS BOILER WITH TWO COMBUSTION CHAMBERS |
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| 申请号 | EP05776149.6 | 申请日 | 2005-06-30 | 公开(公告)号 | EP1815184B1 | 公开(公告)日 | 2009-03-11 |
| 申请人 | Ozcan, Ali Nizami; | 发明人 | Ozcan, Ali Nizami; | ||||
| 摘要 | The new boiler that is subject of the present invention to be used instead of existing solid, liquid, and gas fuelled boilers has been particularly designed to burn solid fuel and liquid fuel or natural gas at the same time, with a high efficiency and it has a different construction from the existing boilers with its improved fully automated grate system driven by engine with reducer that enables continuous coal feed and clinker flow, with its automated lime-fed dry desulphurization system adjustable according to sulphur content ratio in coal, with its special combustion chamber to burn liquid and gas fuels independent from the solid fuel burning chamber, and with its special tubeless design that enables heat transfer via conduction and induction in addition to the radiation based heat transfer, and it is a new type double-fuelled boiler with special tubeless design, which burns coal with fully automated feeding and great ease of operation and without smoke, and which can reduce sulphur dioxide emission thanks to its dry desulphurization system. | ||||||
| 权利要求 | |||||||
| 说明书全文 | The environmental problem caused by air pollution resulting from burning is at the same time an energy problem with regards to the burning of the fuels used. Since the conventional sources of energy on earth are limited, all technological and scientific studies related to the energy problem aim either to find new and clean energy resources or the utilization of the existing energy resources with optimum efficiency. Liquid and gaseous fuels are generally burnt with high efficiency thanks to their homogeneity. However, during the burning of solid fuels, particularly of coal with highly volatile material, the burning efficiency falls significantly because of smoke formation, and the loss of energy can reach to large amounts. Although liquid fuels, particularly natural gas, are becoming increasingly more widespread today, coal is widely used in both thermal electric power plants and for natural heating in coal-reserve rich countries today. In the present state of the art, coal is burnt with relatively higher burning efficiency in industrial boilers through special burners after it is pulverized and fragmented coal is burnt in big capacity boilers used in central heating, either in liquidized bed systems or mechanically loaded stokers. However, in the existing small and medium capacity, hand loaded hot water and steam boilers generally used in heating, coal is burnt with very low efficiency on the grate, and smoke and polluting emulsions resulting from incomplete combustion lead to air pollution. On the other hand, the existing solid fuel boilers produced with rather old technology are transformed into natural gas boilers through some mechanical modifications when the use of natural gas is preferred in an attempt to prevent air pollution; however, it isn't possible to burn natural gas efficiently in such boilers. The fully automated double-fuelled smokeless and tubeless boiler with special design, continuous coal feed, specially improved dry desulphurisation system, and two combustion chambers that is subject of the present invention, designed to be used instead of the existing solid oil boilers and taking into consideration the fact that the use of natural gas is spreading, is a new type special tubeless design double-fuelled boiler, which burns coal with fully automated feeding, smokeless and with a great efficiency, which can reduce sulphur dioxide emission thanks to its dry desulphurisation system, and which can also burn liquid fuel or natural gas with high efficiency in a second combustion chamber without any need for any modifications. Before detailing the technological differences between the novel boiler and the existing liquid and gas fuelled boilers, it would be appropriate to briefly outline the concept of combustion, full combustion, combustion characteristics of coal and the formation of smoke and pollutant emulsions. Combustion is a chemical process, in which carbon and other combustibles in solid, liquid, or gas fuels combine with oxygen over a specific ignition temperature to produce heat and light energy. The combustion reactions of carbon and other combustibles and the amounts of produced heat are as follows: The incomplete combustion reaction of carbon resulting in carbon monoxide when there is insufficient oxygen and the combustion reaction of carbon monoxide again with the provided oxygen is as follows: Since in practice oxygen is provided from the air, the fuel must be in contact with air to burn. In a combustion process, in addition to a sufficient supply of air, the following three conditions should be met:
In literature, this condition is known as the "Three T's of Combustion: Temperature, Turbulence and Time". In terms of burning technique, the complete combustion of fuel in a burning system primarily requires a sufficient supply of air and the mixing of fuel and air in turbulence above an ignition temperature that may change according to the type of the fuel, and this condition should be maintained for a definite period of time. A burning system providing these conditions during the combustion of liquid in solid, liquid, or gas states ensures complete combustion and also smoke-free combustion, since smoke is a product of incomplete combustion. Coal is a solid fossil fuel consisting of various combustible materials, humidity, and incombustible mineral substances. During the combustion of coal, combustible substances including fixed carbon and volatile substances burn and minerals are left as residues in the form of ash. Coals are generally classified according to fixed carbon, volatile substances, humidity, and ash ratios they contain. Based on this principle, there are three groups of coals termed respectively as "anthracite," that is coal with a very low ratio of volatile substance; "bituminous," that is cola with medium level volatile material; and "lignite," that is coal with a high level of volatile substances. When coal is heated, the volatile substances contained in coal go through distillation even at temperatures under the ignition temperature and are emitted in the form of combustible gases (hydrocarbon gases and tar vapour). The coal consisting of fixed carbon remaining after these volatile substances are completely distilled is called "coke". Thus, two fuels in gas and solid states, respectively the combustible gases emitted as coal is combusted and the fixed carbon, burn together at the same time. Since the ignition temperature of the emitted combustible gases is higher, the fundamental problem in burning coals with high levels of volatile substances such as the lignite coal is providing the required conditions in the combustion chamber to ensure complete combustion of fuels in two separate states (solid and gas) at the same time. As a result of the fact that the technical specifications of combustion systems do not provide the above mentioned complete combustion conditions, incomplete combustion takes place particularly when burning coals with high levels of volatile substances such as the lignite coal. Two separate types of smokes are formed in combustion systems based on the conditions during incomplete combustion. If the temperature in the combustion chamber is lower than the ignition temperature of the emitted combustible fuels, hydrocarbon gases exit the system in the form of smoke through the flue without burning even if there is a sufficient amount of air. This smoke consisting of unburned hydrocarbons and tar vapour is called brown smoke (grey smoke) due to its brown (or, depending on the type of the coal) grey colour. The formation of brown smoke leads both to fuel loss because of the hydrocarbon gases, about 75% of which methane gas, exiting from the flue before they can be combusted, and to the loss of energy they contain as they are heated up to the flue temperature. If a sufficient amount of air cannot be provided or the combustible gases cannot be mixed in turbulence even if there is a sufficient amount of air and although the temperature in the combustion chamber is above the ignition temperature, incomplete combustion will once again take place. Despite the fact that strong burning takes place at places where there is oxygen, at places where there is a lack of oxygen or where its contact with combustible gases is not provided through good mixing, cracking reactions take place due to the high temperature, which leads to the formation of carbon particles, which exit the system in the form of soot and black-coloured smoke. This black smoke consisting of particles also leads to a significant energy loss both because of the unburned fuel, which are carbon particles, and the energy these particles carry from the combustion system as they are heated. If the distribution of heat is not homogeneous within the combustion chamber, both grey (brown) and black smoke can form at different places in the combustion chambers. As it should be apparent from the facts outlined above, the fundamental reason of smoke formation during the combustion of coal is the inability to fully burn the emitted combustible gases, that is to say, incomplete combustion. If combustible fuels are completely combusted in the combustion chamber, the formation of smoke will be prevented and, naturally, energy conservation will be established. Whether in the form of particles or unburned hydrocarbons, smoke formation applies not only to coal but also to liquid and gas fuels. When the conditions of complete combustion are not met in combustion systems burning liquid and gas fuels, as well, the two types of smokes in question will inevitably be formed. However, since liquid and gas fuels are more homogeneous and thus easier to burn completely, and since liquid and gas burners are designed to enable higher combustion efficiency and equipped with automated control systems, in practice smoke-free combustion is easily achieved in liquid and gas boilers with appropriately designed combustion chambers. On the other hand, carbon monoxide (CO), one of the pollutant emissions, is formed similarly, because of lack of sufficient oxygen in the combustion chamber, and is produced as a product of incomplete combustion. However, the sulphur dioxide (SO2) emission produced by the burning of sulphur contained in the body of fuel is not a product of incomplete combustion but a product of burning produced by the burning of sulphur. Therefore, since it is not possible do directly reduce the emission of sulphur dioxide through efficient burning; the reduction of the sulphur dioxide emission is only possible via the dry desulphurisation system provided by the addition of lime or similar chemical substances in the combustion chamber, or via the wet desulphurisation system applied on flue gases. Nitroxides (NOx) produced by the burning of nitrogen contained in the body of the fuel or in the air at particular combustion chamber conditions, particularly at high temperatures, are also products of burning. The formation of NOx depends more on the conditions in the combustion chamber than on the fuel. We can express the pollutant emissions combining them in two groups as follows: Sulphur dioxide (SO2) emission emanating from fuel can be reduced by improving the fuel via certain physical or chemical processes to reduce sulphur contents or with the methods known as dry or wet desulphurisation, rather than the combustion system itself. The addition of systems based on these systems to the combustion systems or designing them with the combustions system are possible. The redox equations for sulphur or sulphur dioxide in the fuel body with the desulphurisation process are below: The smoke (particles and unburned hydrocarbons), carbon monoxide (CO), and nitroxides (NOx) emanating from the combustion system can be reduced with an appropriate burning system and combustion chamber design. The existing hot water and steam boilers used in heating and industrial steam production today can be classified into two groups in terms of their manufacture and construction specifications, namely welded steel boilers and sectional cast iron boilers. In terms of their capacity to fire solid, liquid, and gas fuels, the boilers in these two groups can be outlined as follows. The boilers in this group can be used in both house/apartment type domestic heating and for industrial purposes. Based on their constructional specifications, these boilers can be classified in two main groups.
Water-tube boilers are mainly used in high capacity central heating installations or for industrial purposes. These boilers can burn solid fuels when mechanical coal burners (stokers) are installed in the front instead of liquid or gas burners. Gas-fire tube boilers are used in smaller capacity central heating installations and small capacity industrial steam production. This type of boiler can be classified into three separate groups with regards to their constructional specifications and designs.
Semi-cylindrical boilers (DANSK type) are basically designed to burn solid oil and widely used in Turkey. This type of boiler can be used with liquid fuels if boiler grates are made disabled. Cylindrical Three Pass Boilers (SCOTCH type) are mainly designed to burn liquid and gas fuels. Since laying grates in these boilers to modify them into solid-fuel boilers is not productive, they can burn solid fuels only when mechanically loaded coal burners (stoker) or front fireboxes are installed. Cylindrical counter pressure (Reverse Flow) radiation boilers are small capacity boilers designed solely to burn liquid and gas fuels to be used in apartment-type domestic heating. Since a mainly radiation based heat transfer is provided with reverse flow in the small combustion chamber, it is impossible to burn solid fuels in these type of boilers by laying grates. These are also small capacity boilers designed to burn liquid and gas fuels. Some sectional cast iron boilers can burn solid fuels such as coke and briquette. There two types of boilers that burn gas fuels, namely atmospheric burners and blow burners. In high-capacity type solid fuel boilers used in central heating and industry, the coal is burnt via mechanically loaded coal burners (stokers) or in liquidized bed firing systems. Since continuous firing is ensured in overfeed and underfeed stokers and the factor of furnace-stoker is eliminated, the coal can be fired with a higher rate of efficiency in these boilers in comparison to hand-stoked boilers. In liquidized firing systems, an optimum level of air-fuel mixture is provided in addition to continuous burning, which improves firing efficiency to an even higher level. However, the economic applicability of both mechanically loaded coal burners and liquidized bed firing systems to small and medium capacity boilers used in house/apartment type domestic heating is quite limited. The combustion system widely used in apartment type semi-cylindrical boilers is only a hand-stoked, straight grate firebox. In this type of solid fuel boiler, the fuel is burnt on the straight grate laid under the combustion space. The coal is loaded onto the grate with a shovel through the opened firing door in the front and the ashes falling on the ash box underneath the grate are removed with a rake, opening the ash door. Large pieces of clinker remaining on the grate are removed through the firing door by stoking or with a rake. On top of the ash door, there are primary air holes entering from under the grate, enabling burning, and on the upper side on top of the firing door through which the coal is loaded, there are secondary air holes. Flames, smoke, and hot gases coming out of the firebox pass through the second and third pass fire smoke tubes, heating the water in the boiler and reach the flue. The fire smoke tubes clogged up with ' flying ashes and soot are cleaned with a wire brush by opening the front smoke box doors. In the hand-stoked semi-cylindrical boiler, a certain amount of wood is first burnt during the initial firing on the grate and when glowing fire is obtained, the loading takes place by sprinkling coal with a shovel. In the semi-cylindrical boiler, the coal is burnt with two separate methods termed "spill combustion method" and "bedding combustion method". In this method, coal is loaded onto the fire on the grate spreading it with a shovel through the firing door of the boiler. When fresh coal is spilt on the glowing fuel bad as a thin layer, combustible flames emanating to the medium in a fast and uncontrolled way because of the high temperature cannot mix with a sufficient amount of air, which leads to cracking reactions and soot formation as black smoke. On the other hand, when the coal is spilt on the glowing fire as a thick layer, this time the fresh coal disrupts the burning order as it cools down the combustion bed considerably, and starts getting hotter from lowest layers and gasification takes place. Flames and hot gases coming out of the combustion bed at the lower side pass through the coal on the upper layers, rapidly heating and distilling the coal and leading to another uncontrolled emitting of volatile gases. Since combustible gases emitted as such go disperse from the combustion area upwards, they leave the system as unburned hydrocarbons in the form of grey (brown) smoke because of the low temperature, although a sufficient amount of air enters from the secondary air hole. Although the temperature is sufficient on the lowest layer of the coal that gets into contact with the combustion area, however, a big amount of the volatile gases emitted in an uncontrolled way turn into black smoke as a result of the cracking reaction due to a lack of primer air entering from under the grate as limited by flue draught. When the coal at the upper layers reaches the ignition temperature, most of the volatile matters will have left the system in the form of smoke going out of the flue. In this method, the coal is loaded by heaping it on the left and right sides of the grate rather than its whole surface. The aim is to heat up the fresh coal gradually more as compared to the spill combustion method and burn the emitted gases while the coked coal is burning on the other side. However, although gases are emitted over a longer period of time, because the emitted gases are oriented to the back of the combustion space along with the hot gases emitted from the coke fire and because they get into contact with the cold surfaces, again most of the gases leave the system in the from of grey smoke. Thus, although the grey smoke emitted in this method is less dense as compared to that emitted during the spill combustion method, it covers a longer period. When the coal stacked in the form of bedding is distilled and ignited, it emits black smoke because of incomplete combustion resulting from high combustion bed thickness. It should also be mentioned that since the secondary air entering from top is made more disabled, the productivity drops due to an excess of air. As evident from the above, since the conditions of complete combustion cannot be met in the combustion system be it burnt with coal spilling method or bedding on straight grate, it is impossible to prevent brown (grey) or black smoke formation in semi-cylindrical boilers. The smoke exhausted from the flue consists of unburned hydrocarbons and carbon particles, which means that a significant amount of fuel is lost from through the flue. In practice, central heating fire stoking operators fail to properly use either of these methods as required by the related techniques and load a large amount of coal into the boiler at once for ease of operation. Thus, fuel loss reaches maximum levels as grey smoke first, then black smoke (soot), and carbon monoxide forms on an excessively thick combustion bed. Soot and creosote abundantly produced as a result of bad and inefficient burning block the fire smoke tubes in a short time, which leads to operational losses due to a need to clean the pipes frequently, and the heating productivity of the boiler is reduced as the creosote layer on pipe surfaces makes the heat transfer difficult. In addition, in semi-cylindrical boilers, as the hot clinker is taken out with a rake through the opened firing door, unburned pieces of coal fall under the grate or outside and ash losses also increase. The excess air entering in the boiler during this process reduces boiler efficiency and the carbon monoxide emission of the not fully burn hot clinker taken out sometimes constitutes a threat for the health of the boiler operator. As should be obvious from the above, in the widely used hand-stoked, straight grate traditional semi-cylindrical boilers, which are the products of a considerably old technology, the conditions for complete combustion cannot be met, which leads to a very inefficient burning of coal, and the formation of an abundance of smoke cannot be prevented. Since flue and ash losses reach to a maximum level, the loss of energy due to unburned fuel increases at the same degree. In addition, the human factor plays an important role in daily operation and operational difficulties reduce productivity even further. The combustion system of the sectional cast iron boilers designed to burn solid fuels basically consists of a hand stoked firebox, too, and primary air enters to the system from under the grates and secondary air enters through the holes above the firing door in the front of the firebox. Sectional cast iron boilers are designed to burn degassed coals such as coke and briquette, the coal in these systems is burnt on a thick combustion bed in the small grate area. As it is the case with the semi cylindrical boilers, solid fuel sectional cast iron boilers are loaded by throwing coal through the firebox with a shovel and the grate is removed with a rake through the same door. However, these kinds of boilers do not allow coal burning with the bedding method due to small grate area. As is the case with the spill combustion method, the coal filled as a thick layer leads to the formation of grey smoke because of a failure to burn the abundantly emitted volatile materials and to the formation of black smoke after a rapid burning starts. When coals with very low contents of volatile materials such as coke, briquette, and anthracite are used instead of coals with very high level of volatile materials such as the lignite, a higher level of burning efficiency is achieved. However, when coals with high levels of volatile materials are used, the combustion productivity in these boilers can be even lover than that in the semi cylindrical boilers. In boilers designed to burn liquid and gas fuels, the function of firing system is accomplished by the fully automated liquid and gas fuel burners placed in the front of the boiler. The burner is activated at a temperature set by the thermostat triggered by the boiler outlet water temperature and automatically deactivated when a certain temperature is reached. Thanks to this automatic deactivation feature of the burner, other control systems providing control depending on the outer weather temperature can also be applied easily to these boilers. In liquid fuel boilers, fuel-oil known as the central heating fuel is widely used. The liquid fuel burner is able to spray the fuel-oil, which is a homogeneous fuel, into the combustion chamber of the boiler with the firing air with turbulence and when the boiler combustion chamber design fits the spraying angle of the burner and its firing capacity, the conditions of complete combustion are achieved and smoke formation is prevented. The burning efficiency can be increased by adjusting the air-fuel mixture in the burner, and the adjustment of the burner nozzle enables operation at a desired capacity within the capacity limits. However, when a proper air-fuel adjustment is not fulfilled or in situations where the combustion chamber of the boiler is not suitable, complete combustion is not achieved and smoke can form and leave through the flue in the form of soot and unburned hydrocarbons. Natural gas is widely used as fuel in gas fuelled boilers. There are two types of gas fuel burners namely pressure jet burners and atmospheric burners. Atmospheric burners can only be used in specially designed boilers for atmospheric burners. On the other hand, pressure jet burners can be applied on cylindrical three pass boilers, cylindrical counter pressure radiation boilers, and three pass sectional cast iron boilers. The conversion of semi cylindrical type boilers designed for solid liquid to be used with natural gas has been deemed appropriate by the authorized gas distribution authority within the framework of the Natural Gas Conversion Project, therefore, pressure jet natural gas burners were applied on this type of boilers with the condition that the grates are made disabled and requested modifications are made. However, since it did not prove to bring good results in practice, this was not continued. In cylindrical three pass steel boilers and iron cast three pass boilers, the air-gas mixture delivered to the combustion chamber by the burner completes burning in the cylindrical combustion chamber and hot gases produced by burning pass through the second and third transition pipes or channels to leave the boiler and reach the flue. The heat transfer in cylindrical three pass boilers is provided by radiation in the combustion chamber and by convection and conduction in the second and third transition pipes. In this type of boilers, it is possible to clean the pipes with a wire brush opening the front fume cupboard doors in case soot and creosote that can be produced as a result of incomplete combustion due to a malfunction of burner air setting because of incorrect operation or other reasons. In counter pressure radiation boilers, however, the air-fuel mixture delivered to the central axis of the cylindrical combustion chamber with the burner provides turbulence with reverse flow as it returns from the boundaries of the combustion chamber, of which backside is closed, and this leads to an increase in burning efficiency and a second transition within the combustion chamber takes place in a sense. Hot gases returning to the combustion chamber with reverse flow, the said hot gases being the products of burning, pass through the surrounding fire smoke tubes to leave the boiler with reverse flow. Heat transfer in this type of boilers is mainly provided by radiation in the combustion chamber due to reverse flow. These types of boilers are termed as "Boiler with reverse flow furnace" in literature. When natural gas is used as fuel and since radiation is lower in natural gas as compared to liquid fuel, the heat transfer in fire smoke tubes gains importance and turbulators are placed in the pipes to increase the heat transfer rate on a unit surface. However, since it is not possible to open the front door, to which the burner is connected, during operation as the natural gas pipe installation and the burner is fixed, an opportunity to clean the creosote resulting from soot that can be produced as a product of incomplete combustion due to insufficient air resulting from a deterioration in the burner air settings, which may lead to a drop in the heating efficiency in the pipes under operational conditions. In semi cylindrical boilers converted to natural gas burners from solid fuel burners, the burning efficiency in the semi-cylindrical combustion chamber is lower as compared to cylindrical boiler, natural gas flue gas temperature drops considerably as the heating surfaces of second and third smoke pipes calculated according to solid fuel are large, which leads to an increase in the general heating efficiency of the boiler but at the same time, excessive concentration and corrosion problem in the boiler and the flue emerges resulting from the excess water vapour in natural gas produced by burning. The conversion of boilers designed for solid fuel or being operated with solid fuel to be able to operate with liquid and gas fuel is a current issue today brought up particularly to prevent air pollution resulting from burning. The conversion or the required mechanical modifications required for the convertibility of existing solid fuel boilers in operation to be able to use liquid fuel or natural gas fuel can be outlined as follows: Big capacity water piped boilers or fire-smoke tube cylindrical boilers, on which mechanical coal burners (stoker) or front furnaces are assembled, are transformed into liquid or natural gas boilers by a complete dysfunction stoker or the front furnace and assembling liquid fuel or natural gas burner on them following the required modifications for burner connection. The conversion of solid fuel semi cylindrical type boilers, widely used particularly in Turkey, to liquid and natural gas boilers is possible by removing the grates inside the boiler. After the removal of the grates lain under the semi cylindrical combustion space, the ash box underneath the boiler is filled with ash and soil and fireclays are lain on top of it at the level of the grate. The firing door of the boiler is removed and burner connection flange is assembled instead and liquid fuel installation is lain if it is going to be converted to be a liquid fuel boiler and natural gas installation is lain if it is going to be converted to be a natural gas boiler, after which liquid or gas fuel burner is assembled, and thus semi cylindrical boiler is converted to be a liquid or gas fuel one. Further, if there is not any explosion door, an explosion door is duly opened in line with its technique. The convertibility or the required mechanical modifications required for the convertibility of existing liquid fuel or natural gas fuel boilers in operation to be able to use solid fuel can be outlined as follows. In order to convert a semi cylindrical boiler operating with liquid or natural gas back to a solid fuel one, firstly liquid fuel burner installation or natural gas installation as well as the burner installation must be removed from the front of the boiler completely. Then the fireclays and the soil in the ash box and grates are laid instead, firing door is reassembled to the front to convert it a solid fuel one. Since the desired efficiency cannot be achieved via hand stoking for semi cylindrical boilers with a capacity of 2500000 kJ/h (600000 kcal/h) (heating surface (100 m2), conversion to the system using coal is done by using mechanically loaded coal burners (stokers) in boilers with a greater capacity. It is not possible to convert a cylindrical three pass boiler operating on liquid fuel or natural gas to a solid fuel burner by laying grates in it. However, big capacity cylindrical three pass boilers used in industry and steam production can be transformed into solid fuel ones by the installation of mechanically loaded coal burners or front furnaces instead of burners. This type of cylindrical boilers is also not possible to be converted into solid fuel boilers by laying grates inside. The system can be converted to be a coal fuel one by replacing this boiler with a semi cylindrical one. It is not possible to convert sectional cast boilers with atmospheric burners designed to burn only liquid fuel and natural gas to solid fuel ones. However, the conversion to solid fuel boiler of the types of such boilers designed to burn both liquid fuel and solid fuels like coke and briquette is possible by removing the burner and installation and laying special grates inside the boiler, as is the case with semi cylindrical boilers. On the other hand, if the heating surface of the boiler is selected according to the liquid fuel calorie, new sections are required to be added when such boilers are converted into solid fuel ones. The present invention, the "Fully automated double-fuelled smokeless and tubeless boiler with special design and continuous coal feed, specially improved dry desulphurisation system, and two combustion chambers," is a new type of boiler designed by the further improvement of the boiler described in patent As can be seen in As seen in The air delivered to the combustion unit with the forced air blow fan can also be adjusted automatically via a thermostat, which triggers the forced air blow fan, controlled by the boiler water temperature. On the front upper side of the boiler that is subject of the new invention, on the front side of the water walled fresh coal bowl created with special design, a secondary air canal made from thin sheet iron, in which the secondary air flows, is constituted. The lower side of the bowl has a special design and an inclination that enables the flow of the coal due to its own weight and the second part of the secondary air canal (25), which heats the air coming from the secondary air canal from top, around the coal loading nozzle or, in domestic type low capacity boilers, around the coal loading door is above the bowl. In the lime bowl on the upper side of the coal distillation canal, where the coal in the bowl is distilled via preheating before going to the combustion chamber, there is a lime flow opening (27) with a lime adjustment damper (26), through which ground lime flows downwards and which provides the opportunity to adjust the flow rate of ground lime according to the sulphur contents of the coal. Thanks to the special movement grate system (32) with step design that is capable of moving forward and backward on the roller gears (31) mounted on the side walls of the combustion chamber via the connection rods (30) connected to the eccentric shaft (29) actuated by the drive of the motor (28) with external reducer located under the solid fuel combustion space of the new boiler as shown in the figure, the automatic and continuous dropping of the ashes in the combustion chamber to the ash bowl and of the big clinker pieces to the clinker bed through the clinker canal is made possible with the motor with reducer, which is automatically activated as required. The bowl is fed with coal through the coal feeding auger, which is activated automatically as a result of this movement, and the coal in the bowl automatically progresses towards the distillation canal below. At the upper rear part of the clinker canal at the end of the combustion chamber, there are clinker cutter blades (33) that cut the hard clinker pieces to ensure that clinker falls down without turning into blocks as shown in the figure. On the upper side of the clinker canal, between the clinker canal and the flame passing canal there is the water jacketed middle compartment (34) shaped with its special radius design as shown in the figure and the middle compartment is divided into two to form the upper compartment with radius (35) that constitutes the rear wall of the canal (20) as it is oriented upwards and the lower compartment with radius (36) which constitutes the rear side of the clinker bed as it is oriented downwards as shown in the figure. On the side of the new boiler that is subject of the present invention, there are three doors which are the ash bowl door (37) used to take out the ashes falling from the grates and accumulating in the ash bowl, the clinker bed door (38) used to take out the big clinker pieces falling from the clinker canal to the clinker bed, and to further back, the door of the creosote bowl (39), in which creosote and flying ashes descending through the second and the third passing canals accumulate. On the side of the boiler as seen in the figure, two covers on each of the left and right sides, one of which functioning as the firing door (40) opening to the solid fuel combustion space and used in initial firing, the other functioning as the explosion door (41) during the combustion of liquid - gas fuel and opening to the infernal and used in removing the accumulated flying ash and creosote. In the new boiler, fresh coal loaded automatically to the bowl of the solid fuel combustion unit with the feeding auger automatically progresses from the coal distillation canal towards the combustion space of the furnace with its own weight and from time to time, with the support of the connection rods connected to the eccentric shaft actuated by the drive of the motor with external reducer as well as the movable grate hands. Coal distilled through gradual preheating can be burnt completely with its revealed combustible gases and the coked fixed carbon part smoke freely in the complete combustion conditions in the combustion chamber. Ashes remaining after the combustion fall to the ash bowl under the grates, and the clinkers remaining on the grates fall to the clinker bed behind the solid fuel combustion unit with the stepped movement of the moving grates moving automatically forward and backwards. The ash and clinker in the in the ash bowl and clinker bed slide towards the ash-clinker auger and taken out with the automatically operating ash-clinker auger. Thus, while coal is fed via the fully automated mechanism that ensures a stabilized flow, ashes and clinker remaining after combustion leave the combustion space automatically thanks to this mechanism, which provide a stabile and uninterrupted burning. In the meantime, in parallel to the mentioned automatic and uninterrupted combustion process, the dry desulphurisation system reduces the sulphur dioxide emission that can form with the desulphurisation of the sulphur contained in the body of the coal to a minimum thanks to the ground lime flow rate that can be adjusted according to the sulphur contents of the coal based on the type of the coal. At the lower side of the water jacketed vertical compartment (42) in between the second lower vertical passing canal (21) and the third upwards vertical passing canal (22) on the back side of the new boiler, there is an ash-creosote box (43) serving as cyclone, in which flying ashes and creosote accumulate. In order to increase the efficiency of heat transfer via conduction in the third vertical passing section, provided are special turbulators (44) made from stainless steel designed in the form of wings in between the water jacketed vertical compartment and the vertical and water jacketed rear wall of the boiler. Gases produced by the combustion leave the boiler passing out through the boiler flue canal (45) when they complete the third vertical passing. In the boiler that is subject of the present invention, installation return water enters the boiler through the return water flange (46) on the upper side of the solid fuel and liquid fuel/natural gas combustion chambers on the front side of the boiler, and therefore, mixes with the hot water elevating from the return water combustion chamber, which also prevents condensation on the surfaces of the boiler. The boiler water exits through the exit water flange (47) on the upper side of the third vertical passing section at the back side of the boiler. As shown in Fresh coal loaded into the bowl of the solid fuel combustion space with the coal loading auger or, in domestic type low capacity boilers, fresh coal filled in the bowl by opening the coal loading door firstly gets into contact with the hot coal in the entrance of the distillation canal and starts heating slowly. The coal in the distillation canal heats up as it takes a certain amount of the heat formed in the combustion space via radiation and conduction. As the coal in the combustion space bums up, the coal in the distillation canal moves towards the combustion space and the coal in the bowl slowly slide downwards due to its own weight and enters the distillation canal. With the lime feeding auger of the special desulphurisation system parallel to the coal feeding auger, the lime bowl is automatically fed with ground lime. The ground lime adjusted according to the sulphur content ratio of the coal approaches the combustion chamber parallel to the flow of the coal downwards. The coal in the distillation canal goes through a gradual distillation as it approaches down towards the combustion chamber, and the volatile matters contained in the coal is emitted in a stabilized way. Combustible gases, which are emitted in a controlled way and which have a higher ignition temperature (600-700° C) as compared to the normal ignition temperature of coal, enter the hottest area of the system on the combustion bed in the combustion space with flue draught and they are burnt after mixing in high turbulence due to the high temperature with the sufficient amount of air heated considerably and coming through the secondary air canals. Since this temperature required for full combustion is retained for some time due to the special design of the combustion space, the formation of smoke in the form of grey and back smoke is prevented at its source by burning all of the gases in these full combustion conditions created in the combustion space. Since the coal in the distillation canal emits most of the volatile materials in its structure at the end of the distillation process, as it slides towards the combustion chamber and enters there, it is already transformed to be semi-coked or coked. While the fixed carbon solid part of the coal entering the combustion chamber of the combustion unit after it has given out all or most of its gases bums with the primary air entering through the specially stepped movable grates, the carbon monoxide created as a result of incomplete combustion in the upper layers of the combustion bed, where air does not fully penetrate, is fired and burnt at high temperatures with the help of considerably heated up secondary air coming from the upper side and along with the combustible gases extracted from the coal in the distillation canal. Thus, the fixed coke part of the previously loaded coal and the gas part of the coal, which is loaded later and is still in the distillation canal, at the same moment under complete combustion conditions, and since a complete combustion of the coal with its solid and gas parts is ensured, smoke formation is prevented. The sulphur contained by the coal chemically reacts with the ground lime transferred into the combustion chamber with the special dry desulphurisation system and turns to calcium sulphate and the formation of sulphur dioxide is prevented again in the combustion chamber. In the combustion chamber, while the part of the ashes and clinker remaining from the combustion that can fall through the grate openings accumulate in the ash bowl, the parts remaining on the grates slide towards the clinker canal at the back of the combustion chamber. At the end of the combustion chamber, this completely burnt ash and clinker are bolted by the front-backwards movement of the special stepped movable grate automatically driven by the motor with reducer and the clinkers remaining on the grates are broken by breaking blades and driven to the clinker canal on the last stair of the grate. Clinkers completely cooling on the clinker canal on the last stair of the movable grate slide with the next grate movement and fall into the grate bowl. Thus, while the ash and clinker remaining from the burning leave the combustion chamber due to their own weight and with the help of the movements of the grates and a fully automated mechanism, the coked coal in the form of glowing fire progresses towards the back of the combustion chamber whereas the coal distilled in the distillation canal enters the combustion chamber as the coal in the bowl slides towards the distillation canal with the fully automated mechanism. To the coal bowl emptied at the end of this process, fresh coal is fed via the coal feeding auger, or in the domestic type small boilers, by opening the bowl door, and the newly fed coal goes through the same process. Thus, complete and smoke free combustion process is repeated uninterruptedly and periodically without any interruption when the coal is being fed and while the ash and creosote is being fallen or being taken out. As is seen, in the solid combustion unit of the new boiler that is subject of the new invention, while the coal fed into the bowl is loaded into the specially designed combustion chamber with a fully automated mechanism, it is distilled in a controlled way via preheating method and burnt with its solid and gas parts under complete combustion conditions with a high efficiency and the losses are reduced to a minimum with a stabile combustion process that is not interrupted even when fresh coal is loaded or ash and creosote is being removed and the maximum combustion productivity that can be reached with solid fuels is achieved. In addition, thanks to the ground lime-fed parallel to the flow of the coal from the bowl to the combustion chamber with the special dry desulphurisation system that can be adjusted according to the sulphur ratio in the coal contents, sulphur dioxide emission is prevented by the dry desulphurisation reaction in the combustion chamber. Before burning coal in the solid fuel combustion unit of the boiler that is subject of the new invention, it should be ensured that the air flap of the blow fan of the liquid or gas burner connected to the entrance of the cylindrical liquid-gas fuel combustion chamber is in the completely closed position. During the initial firing of the solid fuel furnace, after the combustion chamber, distillation canal, and the bowl has been completely filled with coal via the coal feeding auger or, for small type domestic boilers, by opening the specially produced bowl doors, the firing door on the side is opened and some wood is placed on the coal in the combustion space. The wood is fired through the firing door with a suitable igniter or, if the liquid-gas burner is in use, by operating it for a short time to ignite the wood in the combustion chamber from top, after which the firing door is closed. When the coal in the combustion chamber starts burning from top as such and turns into coke as it becomes glowing fire, the coal in the bowl and the distillation channel enters the above explained fully automatic loaded smoke free and uninterrupted combustion process. In the new boiler, the coal type setting flap in the front is adjusted to ensure the burning of all different types of coals with high efficiency. For coals with a high level of volatile materials like lignite, the flap is set to the fully opened position; it is set to the half open position for coals with medium level of volatile materials, to a quarter open position for coals with low level of volatile materials, and the flap is closed when coals with a very low volatile matter ratio such as coke and the like are being burnt. In addition, in the new boiler that is subject of the new invention, thanks to the enhanced special dry desulphurisation system and by the prevention of the formation of sulphur dioxide emission, which can be adjusted by the amount of sulphur in the coal used, economically most advantageous solution is approached. During daily operation an uninterrupted combustion is provided when ash and clinker is removed and when the coal bowl is being filled thanks to the fully automated continuous coal feeding and clinker removal system, which eliminates the need for re-ignition as long as the solid fuel combustion unit is not fully extinguished and wood is used only in the initial firing at the beginning of the season. In domestic type small capacity boilers, it can be considered that automated coal feeding and clinker removal with auger would not be economical and coal loading, clinker removal, and grate moving system can be preferred to be manual. Since this type of small boilers are designed considering that they would be loaded twice a day in the morning and evening under normal operation conditions, at nights the air flap is throttled or the mechanical chain thermostat controlling the air flap is set to a very low temperature to continue with a very low combustion speed. In the morning, the air flap is opened or set at the desired temperature with the mechanical thermostat and it is accelerated by activating the outer hands or the grates with motors with reducers to drop the ashes and clinkers and new coal is loaded in the emptied bowl. The ash in the ash bowl is removed by opening the ash door and the clinker is removed by opening the clinker bed door in the back. With the automatic opening and closing of the main air flap connected to the mechanical thermostat adjusted according to the outer air temperature, both comfort and economy is ensured along with an operation at the desired temperature. As seen in By activating the liquid or gas fuel burner connected to the burner connection cover, the boiler can start operation with liquid or gas fuel immediately. However, naturally it is not possible to operate the boiler with both liquid and gas fuel at the same time. The boiler runs on liquid gas if a liquid burner and installation are connected to the boiler and it runs on natural gas if a gas burner and installation are connected to it. The air-fuel mixture delivered to the entrance of the cylindrical combustion chamber by the liquid fuel or natural gas burner enters the cylindrical combustion chamber designed in line with the spraying angle and capacity of the burner. The air-fuel mixture that has started burning hits the rear wall of the special cylindrical combustion chamber and returns with a circular movement enabling sufficient time for complete combustion and thanks to the turbulence created by the collision of two flows in reverse directions, the fuel is completely combusted. Flames and hot gases that return after they graze the circumferential water walled surfaces of the special cylindrical combustion chamber pass through the flame passing nozzle directed downwards from the lower middle part of the special cylindrical combustion chamber as shown in the figure and are oriented towards the flame passing canal from the upper side of the solid fuel combustion chamber. Hot gases produced by combustion, which are oriented upwards through the flame passing canal, pass through the first vertical passing part, then the second vertical downward passing part, and then the third upward passing canal and leave the boiler through the flue canal. Thus, when the double-passing in the special cylindrical combustion, which has the characteristic of a reverse flow furnace in the new boiler, is considered a total of 5 cases passing take place including the first, the second, and the third vertical passing. In line with the high combustion efficiency of the new boiler, the heating efficiency in the new boiler can reach to a very high level thanks to the two-pass and mainly radiation based heat transfer in the combustion chamber as well as the convection and conduction based heat transfer in the three tubeless vertical pass sections in the last part, where a special stainless steel turbulator is placed. This five-pass construction with special cylindrical combustion chamber, which is different from the existing counter pressure (reverse flow) radiation boilers, does not require the cleaning of the surfaces in vertical passes from ashes and creosote, which increases the productivity of the new boiler even further as compared to the existing boilers. It is known that in particularly the existing counter pressure radiation boilers, to which natural gas installation is connected, it is impossible to open the front cover, to which the burner is connected, to clean the pipes under operation conditions, which leads to a drop in the heat transfer rate resulting from the possible accumulation of soot and creosote on the pipes due to incomplete combustion that can take place due to a deterioration of the burner settings or another reason, all of which lead to the operation of the boiler with low efficiency for a long time. If burning solid fuel in the boiler that is subject of the new invention running on liquid fuel or natural gas is desired, the solid fuel combustion part of the boiler, which is completely independent from the liquid-gas combustion chamber of the boiler, is filled with coal via the coal feeding auger, or if small type boilers are in question, coal is loaded completely by opening the bowl cover, after which the liquid fuel or natural gas burner is activated for a short time, or if the burner is not connected, through the firing door, the coal in the combustion chamber is ignited from the top to immediately operate the boiler with solid fuel. When combustion with solid fuel starts, liquid fuel/natural gas burner is deactivated and burner air intake is set to the closed position. In conclusion, the "fully automated double-fuelled smokeless and tubeless boiler with special design and continuous coal feed specially improved dry desulphurisation system, and two combustion chambers" brings about main solution to air pollution resulting from combustion whereas it facilitates operation considerably and provides comfort parallel to the energy saving it provides due to the high level of efficiency with its specially designed combustion chamber that can burn liquid-gas fuels with a high efficiency, with its enhanced solid fuel intake section containing a fully automated coal feed and clinker removal system that is capable of burning even the coals with high a high level of volatile materials without smoke and with the special desulphurisation system that can be adjusted according to the sulphur contents of the coal and thanks to its new special tubeless construction that is flexible to be able to burn different fuels. |
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