DE102013019090A1 - Process for the preparation of organic, capillary-porous materials, preferably lignites, for the sluice-free continuous entry into a pressure carburetor by means of solids pumps or piston presses - Google Patents

Abstract

The invention relates to a process for the preparation of organic, capillary porous materials, preferably lignites, to an input product for the continuous sluice-free entry in a pressure-charged carburetor with an internal pressure up to 65 bar. The invention is based on the technical object of developing a process for gasification process-compatible preparation of organic capillary-porous materials, preferably of lignites, which makes it possible to feed these materials continuously and without traction to the pressure carburettor with a conventional piston or slurry pump. According to the invention, the technical object is achieved in that the organic capillary porous materials are converted into a granulate having a particle size of less than 20 mm, preferably less than 4 mm, the granules to a moisture content of less than 20%, preferably less than 13%, dried coated dried granules with a water-repellent layer and then transferred by adding water into a suitable both for a sludge pump and piston pump and for the pressure carburetor insert.

Description

The invention relates to a process for the preparation of organic, capillary porous materials, preferably lignites, to an input product for the continuous sluice-free entry in a pressure-charged carburetor with an internal pressure up to 65 bar. Such a generator has no conventional pressure locks via which its loading with the materials to be gasified. After the process, the materials are fed directly and continuously from a piston pump or a piston press via a pipeline in the gasification chamber. The gas pressure of the generator acts directly on the feed system. Outflow of gas via the feed system is prevented solely by the mass and consistency and remanent clamping of the material plug in the pipeline.

The sluice-free entry of fuel with a piston pump or piston press in a pressurized reactor is known and presented several times in the relevant literature.

For example, Horrighs [ Chem-Ing.-computing. 58 (1986) No. 6, p. 522-523 ] the use of a piston press lock for the promotion of coal dust with a piston pressure of up to 400 bar at a back pressure of up to 10 bar. The system has a dynamic lock tube, in which the strand takes over the sealing function according to its compression and length. Reference is made to the use of slip aids to reduce the coefficient of wall friction.

The slurry pump from the manufacturer Putzmeister type KOS is already successfully used for the entry of coal slurry in a pressure gasifier in a power plant in Sweden (power plant Värtan, Stockholm). A mixture of coal and lime is pumped into a pressurized circulating fluidized bed furnace during the entire heating period, which may take up to 6,500 hours. Flotation coal, which is a waste from coal mining, can be recycled with Putzmeister technology and burned as additional fuel in existing coal-fired power plants [ http://www.pmsolid.com/enu/7190.htm , As of 11.07.2013]. In addition, piston pumps are used for the entry of biomass and waste in pressure carburetors.

By means of double piston pumps, highly dewatered sewage sludge up to more than 50 TR (dry residue) can be pumped. The pumps are designed as two-cylinder piston pumps, in which two counter-rotating pistons suck in the material and press it into a delivery line. Eccentric screw pumps are suitable for TR values up to 45% [ Co-incineration of sewage sludge in caloric power plants, Umweltbundesamt GmbH, Vienna, November 2001, ISBN 3-85457-614-5 ].

The usual delivery pressure of thick matter pumps is in the range of about 60 to 150 bar. With such a pressure, it is not possible to densify fine-grained materials with a moisture content of ≤20% even with a long conveying path to a gas-tight material grafting. Such a delivery pressure or pressure is not sufficient to compact the material so that the gas diffusion through the material graft is slower than the conveying speed of the plug. In addition, such a delivery pressure is not sufficient to compress the material plug so that it exerts a sufficiently high remanent pressure (transverse strain) on the channel wall to prevent the gas breakthrough between Materialpfropfen and channel wall with stationary and moving plugs.

With the delivery pressure of a slurry pump sealing against an applied gas pressure by a grafting material is only possible if the porosity of the material graft with gas flow inhibiting substances, eg. As water is filled, and when the length of the pressed product plug is adapted to the back pressure.

• – ausreichende Plastizität des Materialpfropfens, um einer Richtungsänderung des Transportkanals zu folgen, ohne dass der Kanal blockiert wird
• – herabgesetzte Agglomerationsfähigkeit des Materials zur Verhinderung der Bildung eines festen Kompaktats als starren Pfropfen
• – hohe Gleitfähigkeit der Materialkörner im Körnerkollektiv und des Materialpfropfens als Ganzes.

When using a conventional thick matter pump for the continuous charging of a pressure-expanded reactor, the following requirements must be met with regard to the material used and the material plug in the transport channel:

• Sufficient plasticity of the material plug to follow a change in direction of the transport channel, without the channel is blocked
• - Reduced agglomeration ability of the material to prevent the formation of a solid Kompaktats as a rigid plug
• - High lubricity of the material grains in the grain collective and the material plug as a whole.

In the event that the feed system is used to feed a new generation gasifier, the moisture content of the material must be adjusted to <20%, preferably ≤ 13%, to the requirement of effective gasification.

The entry of hard coal with a slurry pump in a pressurized reactor their property is used to have a very low water content and not absorb water. A coal slurry is therefore already pumpable with a water content from 20% and suitable for conventional pressure gasification. The addition of water to hard coal is necessary because the aqueous phase is of decisive importance for the sealing effect of the material plug in the transport channel in relation to the gas pressure.

The entry of soft lignite with a water content of 48 to 62% is not possible because the comminuted raw lignite is not pumped with a slurry pump and the water content as it does not meet the requirement for gasification. The entry of dry lignite with the addition of water is also not possible because the dry lignite absorbs too much water. With a water addition to achieve pumpability, the water content increases in an unacceptable for the gasification area.

• – eine hohe Rohdichte bzw. geringe Porosität durch Anwendung eines hohen Verdichtungsdruckes geschaffen
• – der Feuchtegehalt des Materials gesteigert
• – die Länge des Materialpfropfen erhöht und
• – dem Material Additive zur Verbesserung der Plastizität und der Gleitfähigkeit zugesetzt werden.

In principle, a gas pressure can be sealed by a plug of material, if in the material plug

• - Created a high density or low porosity by applying a high compression pressure
• - Increased the moisture content of the material
• - Increases the length of the material plug and
• - added to the material additives to improve the plasticity and lubricity.

The invention is based on the technical object of developing a process for gasification process-compatible preparation of organic capillary-porous materials, preferably of lignites, which makes it possible to feed these materials continuously and without traction to the pressure carburettor with a conventional piston or slurry pump.

According to the invention, the technical object is achieved in that the organic capillary porous materials are converted into a granulate having a particle size of less than 20 mm, preferably less than 4 mm, the granules to a moisture content of less than 20%, preferably less than 13%, dried coated dried granules with a water-repellent layer and then transferred by adding water into a suitable both for a sludge pump and piston pump and for the pressure carburetor insert.

As organic capillary porous materials lignites (hard lignite, lignite, peat), lignocellulose (bark shavings, wood shavings) and / or sewage sludge are used. In the case of lignites, the transfer into granules takes place by buildup agglomeration or by press agglomeration. The press agglomeration is preferable, since the application of high pressing forces a significantly lower porosity of the agglomerates is achieved over the Aufbauagglomeration. The press agglomeration can be done on an extrusion press. The briquettes are then comminuted to a desired grain size. The agglomeration step can be omitted if briquette, a waste product of the briquetting of lignite with the briquette extruder, is used as granules. Briquette grus has a low porosity and is to be converted by further processing in a hydrophobic material of high plasticity.

The coating of the dried granules with a water-repellent layer is expediently carried out in a mixer. As water-repellent material synthetic oils and / or mineral oils and / or animal fats and / or vegetable fats in proportions of 2-7% by weight based on the granules) are used. Subsequently, the mixture little water (3-7% by weight based on the mixture) is added, whereby this turns into a material system with high compressive plasticity and lubricity, which meets very well on the one hand, the requirements for conveyance by sludge pumps or piston presses and on the other hand has optimum water content of less than 20% for the pressure gasification.

The process step of the agglomeration leads to a granulate having a porosity which is lower than that of the lignites used and which is required for transport by means of thick matter pumps or piston presses into the pressure reactor. Particular attention is paid to the mixing process for coating the dried granules with the water-repellent material. A homogeneous distribution of the water-repellent material on the grain surfaces is the basic prerequisite for the protection of the internal grain porosity from water ingress. Good prospects for the homogeneous distribution of an oil on the grain surface provides a mixer with low mixing speed, in which the oil is sprayed onto the mix, so that the particles are covered by a uniform oil film and not decay by an excessive energy input. Another measure to improve the attachment of the oil to the grain surface is the addition of water vapor during the mixing process. The water vapor serves as a propellant for the distribution of oil on the grain surface, because the oil tries to avoid contact with the water molten coolants and therefore more closely to the Grains binds. The addition of oil prevents the compaction of particles in the transport channel of the conveyor system to a solid, immovable graft. The oil coats the particle surface and inhibits the development of binding forces between the particles. Another important for the inventive method effect of oil coating is the creation of a water-repellent particle surface, which prevents or reduces the penetration of water into the particle structure. By the treatment process according to the invention, the absorption capacity of the dry coal substance for water is significantly reduced. The water supplied to the coated granules is not absorbed by the carbon substance, but remains in the interparticle space between the individual carbon particles. This is the prerequisite for the water to be able to perform its sealing function. In addition, this water can prevent agglomeration of the particles on the one hand even with increased delivery pressure and on the other hand act as a lubricant between the carbon particles and between Materialpfropfen and channel wall and to maintain the transportability of the material plug.

An improvement with regard to non-absorption of water into the grain structure and its fate in interparticular space is the use of hard lignite as a gasification fuel. The hard lignite is a transitional coal between lignite and hard coal. It is characterized in that it has a significantly lower water content in the raw state compared with soft lignite. If hard lignite is dried down to an acceptable water content for gasification, a grain structure with a significantly lower internal porosity compared to lignite coal under the same drying conditions. As a result, the potential water absorption decreases with the addition of the aqueous phase. Low porosity of the dried grain facilitates sheathing of this grain with an oil film. Press agglomeration further reduces the already low porosity of hard lignite.

The method according to the invention will be clarified on the basis of the three following exemplary embodiments:

example 1

Raw lignite with a water content of approx. 53% and a grain size of 0-4 mm is used for the production of build-up granules. The granules are produced in an Eirich intensive mixer with the addition of water. The addition of the water to the raw lignite coal in the working mixer takes place gradually. The water addition stops after the granule germs have formed. The mixer remains in operation, so that the grain size can be increased. When the desired grain size has been reached, the granulation process is ended. The next step is the drying of the raw granules. The desired target moisture content of the built-up granulate is approx. 10%. To improve the sealing effect of the Brennstoffpfropfens the granules should be used with the highest possible packing density. When adjusting the grain size composition of the granules, the fine grain content is of particular importance. It is recommended to set the optimal grain size grading after the Fuller curve. The fine grain fills in the gaps between coarser grains and thereby increases the density of the granulate. After the granules have been produced, the oil is conditioned with machine oil in a proportion of 5% by mass, based on the granules used, with simultaneous steam injection. By steam injection, the water content of the goods increases by about 1%. Subsequently, the oil-conditioned coal water is sprayed depending on the desired water content of the mixture of 15.2%. The result is a granular lignite product of high compressive plasticity and lubricity that meets the requirements for transportability by means of solids pumps or piston presses.

Example 2

Granules are made by crushing lignite briquettes. The briquetting takes place at a pressure of 140 MPa with a coal grain size of 0-4 mm and a Brikettierfeuchtegehalt of 20%. The briquettes are then comminuted to a grain size of 0-4 mm. In the following step, the granules are dried to a water content of about 10%. The adjustment of the optimum grain size composition of the pressed granules takes place after the fuller curve. After the granules have been produced, the oil is conditioned with machine oil in a proportion of 5% by mass, based on the granules used, with simultaneous steam injection. By steam injection, the water content of the goods increases by about 1%. Subsequently, the oil-conditioned coal water is sprayed depending on the desired water content of the mixture of 17%. The result is a granular lignite product of high compressive plasticity and lubricity that meets the requirements for transportability by means of solids pumps or piston presses.

Example 3

Raw hard lignite is comminuted to a grain size of 0-4 mm and then dried to a water content of about 10%. The optimum grain size composition of the comminuted hard lignite is adjusted according to the Fuller curve. After pelletizing by press granulation, oil conditioning is carried out with machine oil in a proportion of 5% by mass, based on the granules used, with simultaneous steam injection. By steam injection, the water content of the goods increases by about 1%. Subsequently, the oil-conditioned coal water is sprayed depending on the desired water content of the mixture of 19%. The result is a granular lignite product of high compressive plasticity and lubricity that meets the requirements for transportability by means of solids pumps or piston presses.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• Chem-Ing.-computing. 58 (1986) No. 6, p. 522-523 [0003]
• http://www.pmsolid.com/enu/7190.htm [0004]
• Co-incineration of sewage sludge in caloric power plants, Umweltbundesamt GmbH, Vienna, November 2001, ISBN 3-85457-614-5 [0005]

Claims (7)

Process for the preparation of organic, capillary-porous materials for the sluice-free continuous entry into a pressure carburetor by means of solids pumps or piston presses, characterized in that the organic capillary-porous materials are converted into granules having a particle size of less than 20 mm, the granules to a moisture content of less than 20% dried, the dried granules coated with a water-repellent layer and then transferred by adding water into a suitable both for a sludge pump and piston pump and in a suitable for the pressure carburetor insert. A method according to claim 1, characterized in that the organic capillary-porous materials are converted into a granulate having a particle size of less than 4 mm and the granules are dried to a moisture content of less than 13%. A method according to claim 1, characterized in that the organic capillary-porous materials are transferred by build-up granulation or by pressing granulation in a granule. A method according to claim 1, characterized in that are used as organically capillary porous materials lignite and / or lignocellulose and / or sewage sludge. A method according to claim 1, characterized in that used as granules in the briquetting of lignite briquettes Brikettgrus is used. A method according to claim 1, characterized by, characterized in that the water-repellent material is introduced in the presence of water vapor. A method according to claim 1, characterized in that as water-repellent material synthetic oils and / or mineral oils and / or animal fats and / or vegetable fats are used.