Claims
1. A drying column for drying brown coal, featured by the fact that its body (1) constitutes a cuboid in which metal roofs (5) and (6) are fastened inside in horizontal layers and in the walls of a column there are inlet openings (4) through which heated air enters the inside of a column (1) and outlet openings (4) through which the air exits the inside of the column (1), where the inlet openings (4) are situated on one side of a column (1), and the outlet openings (4) are situated on the opposite side of a column (1).
2. The column according to Claim 1, featured by the fact that both the inlet and outlet openings (4) are made in layers, where an inlet or outlet opening (4) is situated under each roof (5) and (6) in such a way that if the bottom layer of roofs (5) is equipped with inlet openings (4), then the layer above it is equipped with outlet openings (4), where neighboring layers of roofs are displaced to one another by half a module in a way, which allows brown coal (2) put into the top of the column, falling from the edge of a higher level roof (6) to fall on the roof of a lower layer (5), filling up the place between the roofs of the column.
3. The column according to Claim 1, featured by the fact that both inlet and outlet openings (4) are made in layers, and under each roof (5) and (6) there is an inlet or outlet opening (4) situated in such a way that if a bottom pair of roof layers (5) and (5') is equipped with inlet openings, then the pair of layers situated above it is equipped with outlet openings (4), where neighboring pairs of roof layers are displaced to one another by half a module in such a way that brown coal (2) put into the top of the column falling from the edge of a roof of a higher pair of layers (6) and (6') falls on the roof of a lower layer (5), filling up the place between the roofs of the column.
4. Brown coal dried in the column, according to Claim 1, featured by the fact that it has a given moisture level and caloric value, which is a substitute of hard coal and/or dry wood and/or biomass and/or wet brown coal.
5. Brown coal, according to Claim 4, featured by the fact that brown coal can be transported for long distances, stored, refined and combusted in installations other than professional power engineering plants, not excluding its application in professional power engineering plants.
6. Brown coal, according to Claim 4, featured by the fact that after proper crushing it can be made into briquettes or, through sorting and separating thick fractures, it can constitute natural briquettes. |
Drying column
The basis for this invention is a drying column for drying brown coal and additional applications for brown coal.
At the present time solid fuels most frequently used in households, industrial works and professional power engineering are: hard coal, wood in various forms, and straw. On the other hand brown coal is currently used only in professional power engineering and those heat and power stations are generally located close to the mines from which the brown coal is dug because power stations or heat and power stations must be specifically designed and technically suited to the combustion of brown coal. The reason for these limitations is the high moisture level of brown coal, which makes its independent combustion in the equipment not specially designed and made impossible. Brown coal cannot be used in boilers designed for hard coal or wood because of its low calorific value which is due to its high level of moisture. Boilers designed for brown coal of natural moisture level are not manufactured, and they are not commonly used either in diffuse and industrial power engineering or in households. Only boilers used in professional power engineering have big enough heating surfaces that enable the combustion process to take place according to an exactly-defined procedure within defined parameters. That procedure requires the separation of water from the coal dry mass by means of a pipe dryer and coal mill. Thus, only the professional power engineering sector, which possesses proper appliances and is situated near to a coal mine, is able to use a fuel like brown coal at its natural moisture level. It is common practice for the brown coal to be transported by a conveyor directly from a coal mine to a power plant Due to its high moisture level, often exceeding 60%, brown coal is not transported over long distances nor is it exported. The only way of creating new applications for brown coal, other than in professional power engineering situated near a mine, is to increase its combustible value through drying.
At present the most popular method of drying brown coal, used in works producing briquettes, is to drain the moisture from the coal using drum driers. Maximally crushed brown coal is put into a rotational drum with an axis situated askew or parallel to the level. Under the influence of the drum rotation, hot flue gas and air ventilator draught, the coal as it finds its way into the drum, where it is dried. The source of heat is a furnace situated next to the drum. Different variants of the process are described in patent descriptions dating back to the 1920s.
Another method, commonly used in electric power stations fired by brown coal is a drier, popularly called a pipe drier. A draught of flue gas and hot air affects the stream of crushed coal as it passes through the pipe. After crossing the pipe drier, the coal is transported to the mills, where it is further dried while being ground, again using hot flue gas and hot air.
Still another method is drying in a fluidized bed. The variants of this manner are described in the specifications DE 19931346 and PL344277, but in both solutions fluidized driers are fed by flue gas which separate part of water from the brown coal.
In patent specifications information about pressing water from coal by means of special presses can also be found. For example, such a process was presented in the Polish patent application PL319381. In the solution, reduction of water content in water grainy brown coal is removed as the brown coal is exposed to mechanically applied, initial surface pressure, which lies below the maximum, present in the manner surface pressure and then heat energy is distributed to it, by means of steam which undergoes condensation and heats the brown coal. Then, without further supply of steam, the surface pressure is increased to at least 2.0 MPa which squeezes out the ^vater from the heated brown coal.
The basis for this invention is a drying column for drying brown coal, which constitutes a cuboid in which metal roofs are fastened inside in horizontal layers, and in the walls of a column there are inlets for heated air and outlets through which the air exits the column. The inlets and outlets are located on opposite sides of the column. There is a variant possible where each layer of both inlet and outlet openings is doubled by a layer of additional openings situated below. It is also important that both inlet and
outlet openings are made in layers, where an inlet or outlet opening is situated under each roof in such a way that if the bottom layer of roofs is equipped with inlet openings, then the layer above it is equipped with outlet openings. Neighboring layers of roofs are displaced to one another by half a module in the way, which allows brown coal put into the top of the column, falling from the edge of a higher layer roof to fall on the roof of a lower layer, filling up the place between the roofs of the column. The basis for this invention is also obtained through the drying of the column product, that is, brown coal of a given moisture level. After the drying is complete the brown coal can be transported on relatively long distances, stored, and then combusted in installations other than professional power engineering plants.
The subject of this invention, shown in the drawing where fig. 1 is an axonometric intersection of a column, while fig. 2 shows one diagram of air circulation in the column, fig. 3 shows a column configuration with doubled layers of roofs.
In this particular configuration, the drying column is a metal cuboid 1 open at the top and finished with an extendible floor at the bottom. Inside the column metal roofs 5 and 6 are attached in horizontal layers. In the column walls there are inlet openings 3, through which heated air gets into the column, and outlet openings 4, through which wet air gets out of the column 1 , where the inlet openings 4 are situated at one side of the column 1 and the outlet openings are situated at the opposite side of the column 1. Both the inlet openings 4 and outlet openings are made in layers. Under each roof there is an inlet or outlet opening situated in the manner that if the bottom layer of roofs 5 is equipped with inlet openings then the layer above is equipped with outlet openings. Neighboring layers of roofs 5 and 6 are displaced against each other of half a module in the way that brown coal 2 filled from the top of the column, falling from the edge of the roof 6 of a higher layer, falls onto roof 5 of a lower layer, filling the space between the roofs of a column. Since the roofs are attached to the opposite walls of column 1, they create canals that from one side are finished by an inlet or outlet opening 4, and from the other side are enclosed by a wall 3 of the column 1. As the heated air finds it way to the inside of the column through the openings 4, moves through the canals covered with the roofs 5 and 6 from the top, encounters an obstacle in the form of the wall 3 of the column
1. Local increase in the air pressure forces it through the canal covered with the roofs 5 from the top lengthwise and it penetrates the brown coal 2 layer as it finds its way to the canals created under the roofs 6 of a higher layer, where it moves to the outlet openings 4. The air going through the brown coal 2 layer becomes saturated with moisture gained from it, drying it. The dried coal 2 is received in the bottom area of column 1.
In different option of realization each layer of inlet and outlet openings is doubled by a layer of additional openings ( 4' ) situated below. In this case the openings ( 4' ) are smaller, and the roofs situated in their extension ( 5' ) and ( 6' ) are formed in the shape of a half-open at the bottom pipe, of a triangle or polygon intersection. Doubling the system of openings and roofs improves the efficiency of drying by decreasing the size of cold areas as the air penetrates a layer of brown coal.
The product of this drying process in a drying column is brown coal of a given moisture level which can be transported over relatively long distances, stored and then combusted in installations other than professional power engineering plants.
Laboratory tests prove that drying brown coal allows it to approximate the caloric value of hard coal. A controlled combustion process can only be carried out in a way that brown coal will receive caloric value less than hard coal but higher than dry wood enabling it to carry on the combustion process in hard coal boilers, wood or biomass boilers. On the other hand attempts to combust brown coal of a natural moisture level proved that such coal does not burn unless mixed with a fuel of higher caloric value, caused pasting chimney draft with tarry substances as well as problems of maintaining proper boiler temperatures.
Thanks to drying, that is getting rid of excessTrioisture, transport and storing such fuel will be profitable. The higher caloric value of the dried brown coal will allow it to be used as a substitute for hard coal or dry wood.
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