AU739895B2 - Plant, filter press as well as control and regulating device to reduce the water content of solid materials and/or sludges - Google Patents

Description

AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: Name of Applicant: Maschinenfabrik J. Dieffenbacher GmbH Co.

Actual Inventor(s): Friedrich B. Bielfeldt Address for Service: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Invention Title: PLANT, FILTER PRESS AS WELL AS CONTROL AND REGULATING DEVICE TO REDUCE THE WATER CONTENT OF SOLID MATERIALS AND/OR SLUDGES Our Ref 522165 POF Code: 283870/283888 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): S. -1- The invention concerns a plant, a press as well as a control and regulating device to reduce the water content bound by capillary action in the fibre cells of carboniferous, finely pulverized solid materials and/or sludges, according to the generic part of patent claim 1.

One object of the invention is to enable the large-scale use of lignite by a new method using a thermo-mechanical dehydration, wherein the total efficiency of the current generation in the power station processes is improved and that the continuous throughput of large quantities of carbon-containing solid materials required for this purpose is achieved. To prevent a blow-out at the edges of the bulk material mat due to the steam pressure and to achieve a uniform thermal energy distribution over the pressing area without reducing the steam pressure at the edges a further technical solution for a plant and press is applied which does not contain or prevents the described disadvantages.

This objective is achieved by the method by combining the following process steps: a) an input material is used which at the commencement of the operating cycle is subjected to steam using a steam overheated up to a150°C in an essentially steam-tight enclosed pressure chamber which is pre-heated up to over 1000C, **wherein b) the compression pressure on the input material is greater than the pressure caused in the input material by the bulk density, corresponds approximately to the maximum of the applied steam pressure of 5 to 8 bar and subsequently after having reached a temperature of approx. a125°C in the input material the steam injection is terminated and depending on the grain size of the input 25 material a higher mechanical, specific compression pressure up to a maximum of bar will prevail to reduce the residual water content up to 20% of the weight.

Corresponding to the thermo-mechanical dehydration method according to Australian Patent Application No. 60639/96 it is possible to dehydrate lignite economically with a low usage of thermal and mechanical energy. To generate current from lignite with high moisture content the total efficiency of the power plant process can be clearly improved by connecting upstream the energy-advantageous method according to the invention to remove the water. In addition, when compared C:\WINWORD\GAYNODELETE\522165.DOC with known thermal drying methods, energy used for the vaporising of the water is saved.

A further objective of the present invention is to provide a plant to carry out the process steps according to Australian Patent Application No. 60639/96. This is achieved by use of a circulating dispersion belt that is passed through a pressure chamber integrated in a single-stage press and this pressure chamber is opened and closed by a lock system in accordance with the cycles of the process stages, wherein the main parts of the plant comprise a reversible, continuously operating dispersion machine, an intermittently operating filter press which can be heated and lO a dispersion belt box system with a rectangular dispersion pattern for the lignite granules, whose endless dispersion belt is guided by two endless lateral steel belts through a pressure chamber, which can be sealed gas-tight, in the press and wherein transversely to the direction of transport at the entry and outlet of the pressure chamber it can be closed and opened by a blade which can travel up and down and a gate valve.

Since for great power plant outputs, e.g. for a one gigawatt power plant output, several press lines, each with a lignite throughput in the supply region of approx. 200 t/h have to be used and the drying process is carried out in cycles of approx. 10 min each, this quantity has to be supplied by the dispersion machines to the pressure chamber intermittently six times per hour, i.e. approx. 33 t per supply process. This means that in the case of a bulk weight of approx. 600 kg/m 3 approx.

m 3 granulated lignite has to be transported into the pressure chamber with a transport speed of approx. 0.5 m/s within approx. 70 s evenly with the rectangular dispersion pattern. Therefore the problem is to manage the flow of approx. 0.8 to 25 1 m 3 /s with an even piling height in an intermittent operation. This problem cannot be managed problem-free with a continuous dispersion and a reversible dispersion machine over a stationary dispersion and supply belt. The length of the dispersion and supply belt necessary for this and the space required for same is also disadvantageous as far as the cost of the plant is concerned.

Another object of the invention is to produce a plant with which during a "stop and go" operation of the intermittently operating filter press a satisfactory rectangular dispersion pattern can be produced with a dispersion height of 400 to C:\WINWORDGAYNODELETEA522165.DOC 500 mm from the beginning to the end of the supply operation while the raw lignite granules are deposited flat and thus a quasi-continuous operation, which is intermittent in the direction of transport, will be feasible with small spatial requirements and reduced assembly costs.

As advantage of the invention it can be stated that in accordance with the objective the metering for each dispersion and supply step is carried out evenly exactly within the rectangular dispersion pattern corresponding to the removing velocity of the dispersion and supply belt.

The following features of the plant and the filter press can be listed as advantageous and, at the same time, cost-reducing: the dispersion machine forms with the hopper a constructional unit and is provided in a stationary manner before the filter press, o• *oooo* C:\WINWORD\GAY\NODELETE\522165.DOC loosening and feed rollers are provided for the raw lignite granules in the dispersion machine before the exit opening, the dispersion machine has a discharge slot which can be adapted to suit the throughput of the raw lignite granules and regulated accordingly, furthermore, below the discharge slot of the dispersion machine a vibrating trough is provided which can be adapted to suit the removing velocity of the dispersion and supply belt and for the formation of the rectangular dispersion pattern on the dispersion and supply belt stationary bulkhead walls are provided below the dispersion machine and flexible bulkhead walls up to the filter press as well as displaceable bulkhead walls within the filter press.

A further advantage is that the transfer belt can be provided directly above the hopper and thus the overall length is considerably shorter requiring less room for installation.

Further advantages of the invention become apparent from the following description of the drawing and the auxiliary and subclaims. They show in: Fig.l the plant according to the invention, in a schematically illustrated elevation, when supplying the filter press according to the invention with raw lignite granules during the dispersion and supply *"cycle, o• a Fig.2 the filter press with the dispersion machine according to Fig.l, on a larger scale, Fig.3 the top view of the filter press with the dispersion machine, Fig.4 the filter press, sectioned, from the front, and details of the pressure-chamber system for the inlet and outlet of the filter press according to Fig.2.

The drawing according to Fig.l shows the subject matter of the invention comprising the part of the plant for a thermomechanical dehydrating system for raw lignite granules 6, consisting of: A) a dispersing section for an intermittent bed-like dispersion of the input material on the dispersion and supply belt 4, B) a single-stage filter press 5 with integrated pressure chamber and lock system, and C) the discharge transport of the squeezed lignite slab 31 from the pressure chamber 40 with the pre-breaking device 74 for a subsequent grinding drying.

The dispersing section A of Fig.l shows further the continuous transfer of the raw lignite granules 6 from the transfer belt 2 into the stationary hopper i. The stationary dispersion machine 3, which forms a constructional unit with the hopper i, disperses the raw lignite granules 6 onto the dispersion and supply belt 4, which is circulating through the filter press The dispersion and supply belt system consists of the bottom endless dispersion and supply belt 4 and the bulkhead walls 63 '9 provided vertically left and right from it within the filter press 5 and the bulkhead walls 70 and 76 on the outside. At the same time the dispersion and supply belt 4 is constructed as a o o* steam-permeable woven metal belt and is driven synchronously through the pressure chamber 40 of the filter press 5. The raw lignite granules 6 are dispersed by the dispersing machine 3 up '0~0 to the piling height H with an accurate geometrical rectangular 0000 o cross-section and following this introduced unchanged into the pressure chamber 40 and taken out after being compressed, as o this is illustrated in Figs.l to .ee.o: Figs.l, 2 and 3 illustrate the transport and dispersion system for the raw lignite granules 6 according to the invention. The hopper 1 is continuously supplied by the transfer belt 2 with pre-broken raw lignite, i.e. with raw lignite granules 6. For this purpose the hopper 1 has a storage capacity of approx. two filling units for the operating cycle of the filter press The dispersion machine 3 is provided in the bottom part of the hopper i, forming a constructional unit with it. To achieve a regulated metering of the quantity of the raw lignite granules 6, a build-up of the transport flow within the hopper 1 has to be prevented. For this purpose corresponding vibrating devices 72 are provided on the external shaft walls 69 to achieve a continuous flow of the raw lignite granules 6, in particularly on the inclined shaft walls 69. Within the hopper 1 flow guide boards 67 are provided above the loosening and feed rollers 64, so that the individually controllable functional members are not hindered by the build-up of the bulk material in their function. The flow within the hopper 1 to the loosening and feed rollers 64 is built up geometrically by guide sheets 68.

The dispersion process is introduced intermittently and corresponding to the transport speed (v 0.5 m/s) of the dispersion and supply belt 4 it lasts approx. 21 s. To achieve an as homogeneous depositing on the dispersion and supply belt 4 as possible with a uniform piling height H of approx. 430 mm, the following regulating and/or control processes are provided: The raw lignite granule bed is dispersed between the erect bulkhead walls 70 from the dispersion machine onto the dispersion and supply belt 4 over a width of approx. 2.5 m, i.e. discharged with this width from the hopper 1 by means of a vibrating chute 66. The flow is regulated by means of the dumping height sensor 73 provided directly before the wiper roller 71. At the same time the supply and dispersion process is controlled according to a priority sequence to be determined o 30 experimentally in accordance with the following function chain: the circumferential speed of the loosening and feed rollers 64 in the hopper 1 the discharge slot 65 by means of a valve below the hopper 1, and the removing velocity of the vibrating chute 66 depending from the transport velocity of the dispersion and supply belt 4.

In this manner an over- or under-supply (wave peak or wave valley), which is indicated by measuring the piling height by means of, for example, height measuring wheels 73 and 75 and the height X of the dehydrated lignite slab 31, can be compensated for with the aid of involving the regulating speeds of the above function members. While additionally in the case of an over- or under-supply or when exceeding a tolerance window (maximum/minimum size) the transport velocity of the dispersion and supply belt 4 can be reduced or increased in the course of an adaptive control. By allocating this parameter a uniform piling and dispersion can be achieved within this regulating chain within the stop and go operation.

Simultaneously with the piling of the raw lignite granule bed onto the dispersion and supply belt 4 and the removal of the lignite slab 31 from the filter press 5 the supply of the next raw lignite granule bed is carried out. Before the starting up of the dispersion and supply belt 4 the pressure chamber 40 is opened at the entry 26 and outlet 27 and the bulkhead walls 63 of the pressure chamber 40 are pressure relieved, i.e.

released. The transport of the dispersed bulk raw lignite bed to the exit 27 is carried out by numerical controlling the dispersion and supply belt 4. After the dispersion and supply belt 4 has reached the exit lock II, the pressure chamber 40 is closed again, this means that the bulkhead walls 63 are placed back (approx. 5 mm pressure stroke) and the inlet 26 and outlet 27 are closed again.

The filter press 5 with integrated pressure chamber and lock system in the region B of the pressure chamber press is executed according to the drawing as a stationary single-stage piston press. The dispersion and supply belt 4 travels with the ii raw lignite granulate 6 endlessly from the dispersion section A into the pressure chamber press region B, where it slides over the top, fixed heated pressure plate 13 of the pressure chamber Central horizontal bores in the pressure plate 13 take care of the heating, while vertical steam injection bores are provided equally spaced over the pressure or filter area The top pressure plate 17 is constructed in the same manner.

The pressure chamber system (in the region B) is illustrated in Figs.4 and 5. So that the raw lignite granules 6, brought in the filter press 5 by means of the dispersion and supply belt 4, could be washed around evenly with steam, the material flow is enclosed on all sides and encapsulated in a steam-tight manner.

The pressure chamber system is made up from the following functional elements: Sthe bottom, stationary pressure plate 13, mounted in the press frame the bulkhead walls 63, erected vertically on both longitudinal sides on the left and right, which in turn are pressed laterally by means of the hydraulic short-stroke cylinders 20 against the top pressure plate 17, which is driven by the hydraulic pressure cylinders 34, the long-stroke cylinders 34, which act vertically from the top, and the short-stroke cylinders 20, which press the pressure chamber 40 horizontally from both directions. The cylinders 34 and 20 are allocated to the press frame 30, as 'well as to the longitudinal sides and end faces of the 5 pressure chamber The dispersion and supply belt 4, with the bulkhead walls 63, 70 and 76 constructed as dispersion boxes, are pulled through the pressure chamber 40 synchronously by means of a drum drive O 30 while the vertical bulkhead walls 63 can be displaced horizontally inside the filter press 5, the bulkhead walls 76 are provided in a flexible manner outside of the filter press in the region of the dispersion section A and the bulkhead S walls 70 in a stationary manner below the dispersion machine 3.

As a transport aid for the further transport of the raw lignite granules 6 the bulkhead walls 63, 70 and 76 are equipped with vibrating devices 72. The bulkhead walls 63 inside of the filter press 5 are regulated by means of hydraulic short-stroke cylinders 20 by way of lateral pressure, i.e. relieved during the transporting movement of the dispersion and supply belt 4 and with varying lateral compression forces against the top pressure plate 17 during the steam injection and the pressing process. The top pressure plate 17 is sealed gas-tight against steam pressure by an elastic rubber seal. The bulkhead walls 63 are in turn sealed gas-tight with rubber-elastic seals against the sealed bottom edge of the pressure plate 13, when by means of the hydraulic pressure cylinders 23 the bulkhead walls 63 are pressed vertically downwards during the standstill of the dispersion and supply belt 4. Figs.l, 2, 3 and 5 show the inlet and outlet locks I and II and the inlet and outlet 26 and 27 on the pressure chamber system.

In Fig.l the lock kinematics is illustrated in the open state of the filter press 5 to let in the lignite granule bed.

Simultaneously with the entry of the lignite granule bed into the pressure chamber 40 the gate valve 28 of the outlet 27 is closed in a vertical movement by means of the hydraulic adjusting member 36 for the subsequent steam injection process.

At the same time the gate valve 22 in the inlet 26 is moved up so far, i.e. released, that the lignite granule bed with the piling height H (see Fig.5) can be moved trouble-free into the pressure chamber Figs.4 and 5 show the pressure chamber in the closed position.

For an isochoric sealing of the lignite granules 6 the top *O g pressure plate 17 is also moved into position. The gate valve 28 and the gate valve 22 can be adjusted variably to the height S0 X corresponding to the height of the compressed lignite slab 31 0504 or the piling height H. The gate valve 28 is lowered to the raw lignite granules 6 hydraulically, flat, horizontally and vertically by means of the pressing devices 35 and hydraulic O adjusting member 36 and it is moved in a sealing manner against the dispersion and supply belt 4, so that a gap-free seal is formed over the entire width of the dispersion box belt system.

Claims (11)

1. A plant for reducing the water content, bound by capillary action in the fibre cells of pulverized solid carboniferous materials and/or sludges, especially raw lignite, through the effects of thermal energy and pressure on the input material to be dehydrated, wherein the thermal energy consisting of superheated steam and the mechanical energy as surface pressure are supplied and exerted on the input material in a pressure chamber to carry out the process wherein the plant consists of a hopper which can be charged continuously with raw lignite granules, a stationary dispersion machine which can be charged intermittently from the hopper, a filter press which can be heated and is passed through intermittently by an endless dispersion and supply belt according to an operating cycle, which filter press has a gas- and pressure-tight closeable pressure chamber, as well as a pre- breaking device for the dehydrated lignite slab, wherein the dispersion machine has several loosening and feed rollers and a controllable discharge slot for the throughput of the raw lignite granules and from the slot disperses the lignite granules on the dispersion and supply belt with a rectangular dispersion pattern by means of a vibrating chute which can be regulated by the removing velocity of the dispersion and supply belt.

2. A plant according to claim 1, wherein the discharge slot of the dispersion machine, the throughput of which slot can be regulated, as well as the removing velocity of the vibrating chute can be harmonised with the velocity of the dispersion and supply belt in the filter press.

3. A plant according to claims 1 and 2, wherein above the loosening and feed rollers conveying flow-guide boards and guide sheets as well as on the external 25 shaft walls of the dispersion machine vibrating devices are provided.

4. A plant according to claims 1 to 3, wherein the dispersion and supply belt is bound by stationary bulkhead walls on both longitudinal sides in the region of the dispersion machine and by flexibly arranged bulkhead walls from the dispersion machine to the transfer in the filter press.

5. A plant according to claims 1 to 4, wherein the standing bulkhead walls in the dispersion machine and the flexible bulkhead walls between the dispersion machine e.° C:\WINWORD\GAY\NODELETE\522165.DOC and the filter press as well as the adjustable bulkhead walls within the filter press are fitted as conveying aids with vibrating devices.

6. A plant according to claims 1 to 5, wherein after the vibrating chute a wiper roller is provided over the raw lignite granules.

7. A plant according to claims 1 to 6, wherein before the wiper roller or between the dispersion machine and the filter press and after the filter press sensors are provided to measure the height of the raw lignite granules or the height of the dehydrated lignite slabs.

8. A plant according to claims 1 to 7, wherein sensors height measuring wheels lo are provided.

9. A filter press for reducing the water content, bound by capillary action in the fibre cells of pulverized solid carboniferous materials and/or sludges, especially raw lignite, through the effects of thermal energy and pressure on the input material to be dehydrated, wherein the thermal energy consisting of superheated steam and the mechanical energy as surface pressure are supplied to the input material in pressure chambers to carry out the process, (in particular for use in a plant according to claim 1), wherein the rectangular pressure chamber, which can be sealed gas-tight, is constructed from a stationary bottom pressure plate and five hydraulically movable chamber walls, two bulkhead walls rest perpendicularly on the external longitudinal oedges of the pressure plate and are capable of being pressed with variable hydraulic forces against the smooth longitudinal edges of the top pressure plate and the gate valve and the gate valve which can be moved in and out by means of a hydraulic pressure kinematics to close the outlet and by means of hydraulic adjusting members the inlet as well as the top pressure plate between the vertical chamber walls controls hydraulically the compression pressure for the processing stage of steam injection and mechanical pressing by means of the pressure cylinder.

A control and regulating device for a plant according to claim 1 and the filter press according to claim 9, including an operating cycle function control by means of the loosening and feed rollers and the discharge slot of the dispersion machine, the removing velocity of the vibrating chute and the conveying velocity of the dispersion and supply belt can be controlled by that an over- or under-supply is indicated in the control by the sensors and afterwards the work cycle control is regulated.

11. A plant according to claim 1 substantially as hereinbefore described with reference to any of the figures. DATED: 12th March, 1998 PHILLIPS ORMOND FTZPATRJCK Attorneys for: tA ZxA a MASCHINENFABRIK J. DIEFFENBACHER GmbH Co. *oo C:\WINWORD\GAY\NODELETE\522165.DOC