LÖRINCZ LÁSZLÓ (HU)
BOHÁR GÉZA (HU)
LUKÁCS GYÖRGY (HU)
IVÁDY IMRÉNÉ (HU)
HORDÓS-NAGY ZSUZSA (HU)
HOLLÓ ERVIN (HU)
| WO2011142438A1 | 2011-11-17 | |||
| WO1991019893A1 | 1991-12-26 |
| EP2039994A2 | 2009-03-25 | |||
| DE3740257A1 | 1988-07-07 | |||
| EP2287529A1 | 2011-02-23 | |||
| DE3226877A1 | 1984-01-19 | |||
| HU0203046A | 2000-09-22 |
| Claims: 1. A biochip fuelled boiler system which comprises a fuel store, a fuel feeder connected to the fuel store, a combustion unit connected downstream of the fuel feeder, a heat exchanger connected downstream of the combustion unit, exhaust pipes connected downstream of the heat exchanger and pipelines connecting the various units, characterized in that it comprises two separate fuel stores (1 , 3), both of which are provided with a dedicated corresponding fuel feeder (2, 4), of which the first fuel feeder (2) is designed for herbaceous and/or fine chip fuels, the second fuel feeder (4) is designed for ligneous fuels. 2. The boiler system according to claim 1 , characterized in that each fuel store (1 , 3) has an agitator mechanism (1a, 3a). 3. The boiler system according to claim 1 or 2, characterized in that the first fuel feeder (2) is an auger feeder and the second fuel feeder (4) is a hydraulically driven feeder. 4. A biochip fuelled boiler system which comprises a fuel store, a fuel feeder connected to the fuel store, a combustion unit connected downstream of the fuel feeder, a heat exchanger connected downstream of the combustion unit, exhaust pipes connected downstream of the heat exchanger and pipelines connecting the various units, characterized in that it is provided with two heat exchangers (6, 7), supplies of which are different, for supporting two separate functions. 5. The boiler system according to claim 4, characterized in that the first heat exchanger (6) is for hot water supply, while the second heat exchanger (7) is for hot air supply. 6. The boiler system according to claim 4 or 5, characterized in that said exhaust pipe (8, 9) is connected to a flue gas outlet of the heat exchanger (6, 7), the other end of the exhaust pipe (8, 9) is connected through an opening/closing damper (8a, 9a) to an outlet (11 ). 7. The boiler system according to any of claims 4-6, characterized in that at least one of the heat exchangers (6, 7) has a vertical design and is equipped with a mechanical self-cleaning device. 8. A biochip fuelled boiler system which comprises a fuel store, a fuel feeder connected to the fuel store, a combustion unit connected downstream of the fuel feeder, a heat exchanger connected downstream of the combustion unit, exhaust pipes connected downstream of the heat exchanger and pipelines connecting the various units, characterized in that, its fuel store (1 , 3) has a heightened baseplate (16) which is hightened advantageously by legs (15), and is bounded by sidewalls (17, 18, 19), furthermore, is also equipped with a dryer (10). 9. The boiler system according to claim 8, characterized in that the inlet of the heat pipes (14) of the dryer (10) is connected to the exhaust pipes (8, 9) of the combustion unit (5) and/or the heat exchangers (6, 7) for feeding the dryer (10) by flue gases. 10. The boiler system according to claim 8 or 9, characterized in that the dryer (10) is also equipped with a fan blowing air under the fuel store (1 , 3) and/or sucking air from the direction thereof. 11. The boiler system according to any of claims 8-10, characterized in that a spark arrestor is installed in front of the heat pipes (14) inlet of the dryer (10) to capture flammable particles from the flue gases. 12. The boiler system according to any of claims 8-1 1 , characterized in that cleaning doors are placed on the heat pipes (14) of the dryer (10). 13. A biochip fuelled boiler system which comprises a fuel store, a fuel feeder connected to the fuel store, a combustion unit connected downstream of the fuel feeder, a heat exchanger connected downstream of the combustion unit, exhaust pipes connected downstream of the heat exchanger and pipelines connecting the various units, characterized in that it comprises two separate fuel stores (1 , 3), both of which are provided with a dedicated fuel feeder (2, 4), of which the first fuel feeder (2) is designed for herbaceous and/or fine chip fuels, the second fuel feeder (4) is designed for ligneous fuels, furthermore, it is provided with two heat exchangers (6, 7), for supporting two separate functions, furthermore, at least its first fuel store (1) has a heightened baseplate (16) which is hightened advantageously by legs (15), and is bounded by sidewalls (17, 18, 19), furthermore, is also equipped with a dryer (10) with heat pipes (14) located underneath the baseplate (16) of the fuel store (1 ), and the inlet of the heat pipes (14) is preferably connected to the exhaust pipes (8, 9) of the boiler system. 14. A biochip fuelled boiler system which comprises a fuel store, a fuel feeder connected to the fuel store, a combustion unit connected downstream of the fuel feeder, a heat exchanger connected downstream of the combustion unit, exhaust pipes connected downstream of the heat exchanger and pipelines connecting the various units, characterized in that the combustion unit (5) of the boiler system is designed to enable a controlled recirculation of flue gases into its combustion chamber so that the temperature of the firebed is controlled, furthermore, its grate is movable. 15. The boiler system according to claim 14, characterized in that it has a stepped grate. |
The invention relates to a boiler system which is fuelled by biochips and comprises a fuel store, a fuel feeder connected to the fuel store, a combustion unit connected downstream of the fuel feeder, a heat exchanger connected
downstream of the combustion unit, an exhaust pipe connected downstream of the heat exchanger, and pipelines connecting the various units.
Facing the current continuous growth in fossil fuel prices and the ongoing depletion of fossil fuel reserves, it is necessary to return to the use of locally available renewable energy sources, although in a modernised form. In this context, dendromass, agricultural energy plants and their by-products play a key role and can make a significant contribution to a high and rapid growth in local renewable energy production. This is strongly supported by the fact that the price of 1 MJ of energy is 2 or 3 times higher when it is generated from natural gas than in the case of biochips used as an energy source. However, the currently known heat utilisation systems and technologies do not allow the use of biofuels in a bivalent system, the pre-combustion drying of biofuels without additional energy input, or the combustion thereof at lower temperatures, although the land and resources necessary for the production of bioenergy carriers are available.
There are different kinds of biochip fuelled boiler systems designed for specific types of biochips. These include boiler systems designed for herbaceous fuels, the fuel store and feeder of which are designed for the use of herbaceous fuels. There are also boiler systems designed for ligneous fuels, the fuel store and feeder of which are designed for the use of ligneous fuels. Those who wish to use both types of fuels must install and operate two separate boiler systems. The disadvantage of this solution is that either the entire boiler system needs to be duplicated or, where there is only one boiler system, it can only use one type of fuel. In contrast to this, the Hungarian Patent Application No. P0203046 covers a technology that enables the combustion of wood, waste wood or other types of biofuels together with traditional fuels, such as coal, in a boiler designed to be fuelled by hard coal, lignite, peat or other particulate fossil fuels, as primary fuels. This solution includes a process where biofuel is added to the fuel stream after grinding the primary fuel and before the combustion of the ground primary fuel, and the biofuel is burned together with the primary fuel. The described technology provides a solution for the - rather complicated - co-combustion of coal and wooden biofuels, but it does not provide a solution for the use of the combustion unit with both herbaceous and ligneous fuels.
There is a need for biochip fuelled boilers that can be used with both herbaceous and/or fine chip fuels and ligneous fuels. Consequently, the purpose of our invention is to provide a biochip fuelled boiler system that can be fuelled, either simultaneously or separately, by several different kinds of biochips, in particular herbaceous and/or fine chip fuels and ligneous fuels. Our invention is based on the recognition that the underlying problem can be solved by using two fuel stores that serve the same combustion unit and connecting fuel specific feeders to the fuel stores.
For the most part, the currently available boiler systems use one heat exchanger - operating with hot water or warm/hot air, or sometimes steam etc. - for a given function, e.g. hot water supply for greenhouse heating or hot air supply for drying grain. However, there is a need for biochip fuelled boiler systems that can support more than one function alternately, which is the further purpose of our invention. Furthermore, our invention is based on the recognition that the underlying problem can be solved by using a single combustion unit with two heat exchangers operating alternately and, by ensuring in a proper way that the heat exchanger to be operated is switched on while the heat exchanger to be deactivated is switched off, considering the high temperatures at the outlet pipes of the heat exchangers.
The fuels used with biochip fuelled boiler systems often have high moisture content, which is a disadvantage from the perspective of combustion. Therefore, the purpose of our invention is to provide a solution for reducing the moisture content of the fuel entering the combustion unit. Our invention is also based on the recognition that the underlying problem can be solved by an appropriately located and operated dryer at the fuel store.
Accordingly, our invention is, as described also in the attached claims, a biochip fuelled boiler system which has a fuel store, a fuel feeder connected to the fuel store, a combustion unit connected downstream of the fuel feeder, a heat exchanger connected downstream of the combustion unit, an exhaust pipe connected downstream of the heat exchanger, and pipelines connecting the various units, and the boiler system has two separate fuel stores, both of which have a dedicated corresponding fuel feeder, wherein the first fuel feeder is designed for herbaceous and/or fine chip fuels, while the second fuel feeder is designed for ligneous fuels.
The fuel stores are preferably equipped with an agitator mechanism that helps moving the fuel toward the fuel feeder.
In a preferred embodiment, the first fuel feeder is an auger feeder and the second fuel feeder is a hydraulically driven feeder.
Furthermore, our invention is a biochip fuelled boiler system with a fuel store, a fuel feeder connected to the fuel store, a combustion unit connected downstream of the fuel feeder, a heat exchanger connected downstream of the combustion unit, an exhaust pipe connected downstream of the heat exchanger, and pipelines connecting the various units, and the boiler system is equipped with two different heat exchangers designed to support two separate functions. For example, one heat exchanger can be used for producing hot water, e.g. for agricultural greenhouse heating, while the second heat exchanger can be used for producing hot air, e.g. for drying grain.
In the light of the foregoing, the first heat exchanger of the boiler system can work with hot water, and the second heat exchanger can work with hot air, in a preferred embodiment.
Furthermore, in a preferred embodiment, exhaust pipes are connected to the flue gas outlets of both heat exchangers, the other ends of which are connected through opening/closing dampers to an outlet. The heat exchanger to be operated can be selected by setting the dampers. If the damper is closed, the flue gas flow is blocked, and therefore the pertaining heat exchanger cannot work, while the other heat exchanger can.
Preferably, at least one of the heat exchangers is equipped with a mechanical self-cleaning device for cleaning the contaminated heat exchanger. Si and CI can cause deposit formation and/or corrosion in the heat exchangers. For the removal of deposits, it is worth incorporating, primarily in vertical heat exchangers, a mechanical self-cleaning system with the help of which
contaminants can be captured and conveyed into a collection vessel.
Furthermore, our invention is a biochip fuelled boiler system with a fuel store, a fuel feeder connected to the fuel store, a combustion unit connected downstream of the fuel feeder, a heat exchanger connected downstream of the combustion unit, an exhaust pipe connected downstream of the heat exchanger, and pipelines connecting the various units, and the boiler system has a heightened fuel store which has, advantageously, a legged baseplate and is bounded by sidewalls, and is also equipped with a dryer with a heat pipe system located underneath the baseplate of the fuel store.
In a preferred embodiment, the inlet of the heat pipe system of the dryer is connected to the exhaust pipes of the combustion unit and/or the heat exchangers so that the flue gases can be fed into the dryer. This enables the utilisation of the heat content of the flue gases, which would otherwise pass through the chimney, for reducing the high - typically over 25-45% - water content of biofuels to less than 20% without the need for any additional external heat input. This solution also has the advantage of reducing the level of thermal pollution caused by the combustion unit, as well as the amount of solid particles emitted to the air.
Furthermore, in another preferred embodiment, the dryer is also equipped with a fan blowing air under the fuel store and/or sucking air from the direction thereof.
Preferably, a spark arrestor is installed in front of the heat pipe inlets of the dryer to capture flammable particles from the flue gases.
In another preferred embodiment, there are cleaning doors on the heat pipes of the dryer to enable the removal of deposits caused by the flue gases.
An optimal biochip fuelled boiler system according to our invention has a fuel store, a fuel feeder connected to the fuel store, a combustion unit connected downstream of the fuel feeder, a heat exchanger connected downstream of the combustion unit, an exhaust pipe connected downstream of the heat exchanger, and pipelines connecting the various units, and, furthermore, it has two separate fuel stores, both of which have a dedicated corresponding fuel feeder, the first fuel feeder being designed for herbaceous and/or fine chip fuels and the second fuel feeder for ligneous fuels, and two heat exchangers supporting two different functions, i.e. one for hot water and the other for hot air production, as well as a first fuel store which has a heightened, preferably a legged baseplate and is bounded by sidewalls, and is also equipped with a dryer with a heat pipe system located underneath the baseplate of the fuel store, and the inlet of the heat pipe system is preferably connected to the exhaust pipes of the boiler system to enable drying without external heat input, using the heat that would otherwise be emitted into the external environment.
When burning herbaceous plant materials, problems other than those related to the high moisture content also arise, notably from the production of agglomeration prone ash. In order to avoid ash cake formation, it is necessary to ensure through flue gas recirculation into the combustion chamber that the temperature of the firebed can be controlled, and the fuel must be passed towards the ash extraction auger by moving the grate as fast as required by the burning rate. Using a stepped grate can ensure that the ash produced by burning the fuel does not cover the unburned fuel. To this end, our invention is a biochip fuelled boiler system which has a fuel store, a fuel feeder connected to the fuel store, a combustion unit connected downstream of the fuel feeder, a heat exchanger connected downstream of the combustion unit, an exhaust pipe connected downstream of the heat exchanger, and pipelines connecting the various units, wherein the combustion unit of the boiler system has a design that enables controlled flue gas recirculation into the combustion chamber so that the
temperature of the firebed can be controlled, and its grate has a mobile and, preferably stepped design.
Compared to the available solutions, the boiler system according to our invention has the advantage of being designed to support the use of several types of biomass rather than a single type, i.e. it can use herbaceous and ligneous fuels alike, in a wide range of dimensions, whether separately or simultaneously.
Moreover, it can alternately perform two different functions, such as hot water and hot air production. It also enables the utilisation of unused flue gas energy generated in the boiler system for drying the fuel. As a result, the invention enables the use of biochips in an environmentally friendly way.
Our invention is presented in more detail with preferred embodiments by means of drawings.
Figure 1 : Top view of the layout of a preferred embodiment of the boiler system according to the invention. Figure 2: Perspective view of the fuel store of a preferred embodiment of the boiler system according to the invention.
The boiler system shown in Figure 1 comprises an area for the storage and preparation of fuel and a boiler room, and it has a 25 m 3 first fuel store 1 for herbaceous and/or fine chip fuels with a related fuel feeder 2 and a 25 m 3 second fuel store 3 for ligneous fuels with a related fuel feeder 4. The first and second fuel stores 1 and 3 (Figure 2) are legged steel plate containers 15 with a baseplate 16 and sideplates 7, 8, 19, within which two hydraulically operated push floor agitators 1 a and 3a, respectively, are directly connected to an auger feeder 2 and a hydraulic feeder 4 on the side without a sideplate. The second fuel feeder 3 does not need to be heightened by legs.
The fuel feeders 2 and 4 are connected to the feeder inlet of the combustion unit 5 with pipelines 2. The combustion unit 5 is controlled automatically by an electric controller. Two heat exchangers 6 and 7 are connected to the outlet of the combustion unit 5 through pipelines 12. The heat exchanger 6 works with hot water, and the other heat exchanger 7 works with hot air. The outlets of the heat exchangers 6 and 7, respectively, are connected to an outlet 11 by exhaust pipes 8 and 9, respectively, through dampers 8a and 9a, respectively, which have opening/closing functions to select the heat exchanger to be connected to the outlet 11. The outlet 11 is a multicycione flue-dust separator through which the flue gas is passed either into a chimney 13 or a dryer 10 depending on the setting of the changeover device located downstream of the outlet 1 1. The fuel feeder 2 connected to the fuel store 1 designed for herbaceous fuels is an auger feeder worm-driven by an engine located at its end. The fuel feeder 4 connected to the fuel store 3 designed for ligneous fuels is a hydraulically operated pusher. In the fuel stores 1 and 3, material handling can be ensured by push floor agitators 1a and 3a, respectively, a mechanism known in itself. The push floor can be driven by a hydraulic device located underneath. At the first fuel store 1 shown in Figure 2, which is designed for herbaceous materials, the dryer 10 heated by flue gas (or by drying air) ensures that the moisture content of the fuel stored in the fuel store 1 is reduced by heat by the time it enters the combustion unit 5. The essential feature of the dryer 10 is that the flue gases exiting from the combustion unit 5 are fed back to the heat pipes 14 located underneath the fuel store 1. A spark arrestor is installed in front of the inlets of the heat pipes 14 of the dryer 10 to capture flammable particles from the flue gases.
In a preferred embodiment, there are cleaning doors on the heat pipes 14 of the dryer 10 to ensure the removal of deposits caused by flue gases. The dryer 10 is equipped with a fan blowing air under the fuel store 1 and sucking air from the direction thereof, which is not shown in the figure. The exhaust pipes 8 and 9 are connected to the outlets of the heat exchangers 6 and 7, respectively, the other ends of which are connected through opening/closing dampers 8a and 9a, respectively, to the outlet 11. The heat exchanger to be operated can be selected by setting the dampers 8a and 9a.
The heat exchanger 6 working with hot water is a three pass welded steel plate boiler with a transit combustion chamber and standing flue pipes combined from convective heating surfaces, known in its own right. The flue gas is
channelled from the combustion unit 5 into the vertical combustion chamber of the boiler. The flue gas passes from the combustion chamber to the flue pipes constituting the second pass. The flue gas is passed from the second pass to the third pass with the help of a turning chamber. The flue gas exits the boiler through a fume chamber on the upper front wall. The combustion unit 5 has a double shell combustion air preheater, which makes it suitable for burning fuel with higher moisture content, when necessary. The entering flue gas first enters into a large flame tube, and exits after passing through the convective passes of flue pipes. The vertical design prevents the dust contained in the flue gas from depositing on the heat exchanger surfaces. The ash accumulating on the bottom of the boiler is discharged automatically. For the removal of deposits, the vertical heat exchanger 6 is equipped with a mechanical self-cleaning device, which is not shown in the figure, and the other heat exchanger 7 may also be equipped with such a device. The mechanical self-cleaning device automatically performs periodical cleaning, and conveys the removed contaminants to a collection vessel in a closed system. The equipment can also be cleaned through the service doors on top. The heat exchanger 7 is known in itself, and it is used for hot air production.
Fuel feeding is an automated, PLC (programmable logic controller) controlled process. The supply of primary, secondary and tertiary combustion air to the boiler is ensured by built-in fans. The boiler system is suitable for automatically burning ligneous plant fuels, including all kinds of wood chips originating from the sawing industry, the wood processing industry, the trade sector and households, vine and fruit tree pruning, trees in public areas, logging residue, bushes and trees grown in succession areas, firewood chips, wood chips from energy tree plantations, such as acacia, willow, poplar, oleaster, Siberian elm, etc., within the size range of P100 according to standard EN 14961. It is expedient to use fuel the density and calorific value of which is 160-300 kg/m 3 and 11-14 MJ/kg, respectively.
As written above, this boiler system is also suitable for automatically burning shredded herbaceous plant by-products and energy plants, including cereals straw, rape and mustard straw, corn stalks, sunflower stems, sunflower heads, perennial rye, energy cane, energy grass, etc., as well as fine wood chips (within the size range of P16A according to standard EN14961 ). The recommended fuel density and calorific value ranges are 100-300 kg/m 3 and 1 1-14 MJ/kg,
respectively. Considering that the density of the used fuel may vary within a wide range, the auger feeder 2 is controlled with frequency converter for better controllability.
If the moisture content of the fuel in fuel store 1 is higher (higher than 20%, up to 45%), it can be dried with the help of the dryer 10, by feeding back the exiting flue gas (the temperature of which is approximately 180 C°).
At the embodiment of the combustion unit 5 of the boiler system should be taken into account that the purpose is to enable the burning of different fuels with highly varied composition and moisture content in an environmentally friendly manner. Since burning herbaceous plant materials produces agglomeration-prone ash, it is necessary to ensure through flue gas recirculation into the combustion chamber that the temperature of the firebed can be controlled. The fuel must be moved towards the ash discharge conveyor auger as required by the burning rate. A stepped grate is used to ensure that the ash produced by burning the fuel does not cover the unburned fuel. The solution for discharging ash must ensure that the produced ash remains in the combustion chamber for the shortest time possible. The post-combustion chamber should be designed in such way that ensures that the combustion air passed over the combustion chamber is pre-heated
appropriately and the hydrocarbons and the carbon monoxide contained in the flue gas are burnt. The walls must be suitable for operation at permanently high temperatures, which might as well reach 1200 C°. The flue gas exiting from the post-combustion chamber may exit in two different directions, i.e. the direction of heat exchanger 6 or that of heat exchanger 7. At any given time, either heat exchanger 6 or heat exchanger 7 is working. The switchover between the heat exchangers 6 and 7 is made difficult by the high temperature of the flowing medium. For the purpose of bi-directional passage, the post-combustion chamber has a dual connection. The heat exchangers 6 and 7 may be disconnected on both the exit and entry sides on the flue gas side. The above described boiler system can flexibly adapt to the prevailing heat demand at a capacity between 400 - 1000 kW.
The present invention may be realised in many other embodiments, within the scope of protection, different from those described in the examples above, therefore, the invention is not considered to be limited to the examples.