WO2010143003A1

WO2010143003A1 - Equipment and process for the continuous production of fuel from sewage sludge

Info

Publication number: WO2010143003A1
Application number: PCT/HU2010/000046
Authority: WO
Inventors: István PÁLHÁZY; Győző BARABÁS; Márton RÉGNER
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-06-09
Filing date: 2010-04-22
Publication date: 2010-12-16
Anticipated expiration: 2011-12-09
Also published as: HUP0900345A2; HU0900345D0; HU228785B1

Abstract

The invention relates to a preferably closed-loop equipment for the continuous production of fuel from sewage sludge. The invention is characterized in that it possesses three recipient units (1, 2, 3) suitable for the temporary storage of sludge with varying dry matter content, one of which, namely sludge A, has a dry matter content of 18-21%, the other sludge B has a dry matter content of 45-55%, and the third type, sludge C has a dry matter content of less than 6%, there is a dewatering treatment line (I) suitable for achieving a dry matter content of 50-66% connected to a recipient unit (1) for sludge A, there is an aerating and transport unit (7) connected to it, while there is another two stage dewatering treatment line (II) connected to the recipient unit (3) for sludge C to which there is likewise an aerating and transport unit (7) connected.

Description

EQUIPMENT AND PROCESS FOR THE CONTINUOUS PRODUCTION OF FUEL FROM SEWAGE SLUDGE

The subject of the invention is a preferably closed-loop equipment for the continuous production of fuel from sewage sludge, which includes a dewatering unit operating on the principle of electro-osmosis, and a procedure for its use. The equipment and procedure are particularly suitable for processing sewage sludge of varying dry matter content into fuel generated at sewage treatment facilities, treated anaerobically or aerobically and collected.

It is a known fact that high volumes or sewage sludge are generated in the course of sewage treatment at communal sewage treatment facilities. The conventional disposal of sewage sludge containing organic matter poses an ever increasing problem due to environmental regulations becoming increasingly tighter. Several inventions have come to light for its processing and utilization. Among the many known solutions there are alternatives which intend to solve the problem of sludge utilization along with its disinfection by incineration. Hungarian Patent Application under Case No. P9200812, entitled "For the Production and Use of Environmentally Friendly Fuel Composition" describes such a solution. Using this procedure, fuel can be created from sewage sludge with the aid of high temperature steam and appropriate pressure, which can be mixed with conventional fuel and thus utilized. Hungarian Patent Application under Case Number P9004172, entitled "Procedure and Equipment for Dewatering Communal and Industrial Sludge and Waste" describes a procedure for producing a substance of 45% to 65% dry matter content suitable for incineration. Its essence lies in the fact that the pre- treatment of the sludge involves rapid freezing at temperatures between -5 and -1O⁰C, thawing and then drying. According to Hungarian Patent Application under Case Number P0401455, entitled "Process for the Disposal and Utilization for Energy Purposes of Solid Matter Generated as a By-product of Fermentation," solid material is obtained which can be incinerated under appropriate combustion conditions when fed to fluidization firing equipment. In this subject most of the alternatives appearing in foreign patent applications primarily deal with the dewatering of sludge generated. For example, of those specifically dealing with the production of fuel, the equipment and procedure in the German invention description under Publication Number DE 19606640 and the US invention description under publication number US 2008/0022587, are remarkable. One describes the processing of only special sludge called "Klarschlam" using a special incineration process, "Wirbelschmelzfeuerung," while the other description from the USA produces fuel from only a specific material, "Brown Grease," along with producing fertilizer suitable for transport and agricultural use from sewage sludge.

As advanced dewatering is a crucial phase in sludge processing, it is difficult and uneconomical to implement today without a dewatering unit that operates on the principle of electro-osmosis. As a result of the electromagnetic field generated in electro-osmosis and electrophoresis, the cell membranes in the sewage sludge are destroyed, a significant quantity of bound water is released and markedly high dry matter content can be achieved during treatment. Patent description No. PCT WO 2008/029961 describes such a prior art "Electro-Osmotic Dehydrator." It is difficult to avoid incorporating such units in advanced, new and large process lines.

None of the known equipment and/or procedures featured in the inventions contains an alternative comparable to the one subject to our invention, suitable for continuously processing all anaerobic and aerobically pre-treated sewage sludge of varying dry matter content generated at sewage treatment facilities.

A great deficiency in the known and recommended equipment and processes is that they are only suitable for processing sludge in a strongly confined area, those of specific dry matter content and quality, they are complex and their economy is frequently disputable.

The purpose of the invention is to eliminate the deficiencies in the known equipment and processes in order to continuously process - preferably in a closed-loop process - all kinds of sewage sludge, with varying dry matter content and consistency (solid, dilute, etc.), generated at communal sewage treatment facilities into a fuel that can be used to fire the widest range of incinerators featuring various technical specifications.

The invention is based on a recognition that, if the sewage sludge being regularly generated at sewage treatment facilities, treated anaerobically and aerobically, collected, accumulated and separated according to dry matter content and consistency, is fed into equipment, one of whose recipient units is suitable for the continuous receipt and concurrent processing of the most commonly available Type A sludge with a dry matter content of 18-21%, another suitable for that of Type B sludge with a high 45-55% dry matter content, and a third one for Type C sludge with a dry matter content of less than 6%, and, furthermore, if the materials obtained from each stage of the equipment are added in a measured and controlled manner facilitating intervention, mixed and additionally processed, resulting in an end product with specifications suitable for the user, then our objective has been achieved.

In its preferred embodiment, the invention is implemented as described in Claim 1. Claims 2-4 describe preferred embodiments of the equipment that continuously produces fuel from sewage sludge. In its preferred embodiment, the procedure subject to the invention is utilized as described in Claim 5. Claims 6-8, on the other hand, contain the preferred embodiments and stages of the process.

The equipment that continuously produces fuel from sewage sludge described in the invention is demonstrated in greater detail through figures where: 1. Figure 1 shows a schematic drawing of the equipment that continuously produces fuel from sewage sludge, 2. Figure 2 shows an embodiment example of the equipment in Figure 1.

Figure 1 clearly shows that the equipment that continuously produces fuel from sewage sludge possesses three recipient units 1, 2, 3 for receiving sludge of varying dry matter content denoted as sludge A, B, C. The recipient units 1, 2, 3 also play the role of buffer because they often temporarily store the often intermittently arriving sludge shipments, thus assuring the continuous operation of the complex equipment. One kind of sludge, known to occur in the highest quantity, sludge A has a dry matter content of 18-21%, another kind, sludge B, has a dry matter content of 45-55% or above, while the third kind is dilute and fluid sludge C which has a dry matter content of 6% or less. According to our invention, there is nothing to prevent the equipment from being fitted with more than three recipient units, however, this is not usually necessary because sludge differing from the above categories in terms of percentile dry matter content would be processed by directing it to the recipient unit closest to it in terms of percentage. It is important, though, that the equipment should possess at least three kinds of sludge recipient units; for medium, high and low dry matter content because by processing them in accordance with the invention, mixing them in controlled quantities in a manner facilitating intervention will it be possible to provide the most ideal technical conditions for producing an end product V with the desired specifications and consistency.

It is clear in Figure 1 that there is a dewatering treatment line I connected to a recipient unit 1, suitable for achieving a 50-66% dry matter content, which is to receive sludge A and to which there is an aerating and transport unit 7 connected. Connected to the recipient unit 3 which receives sludge C, there is another two-stage dewatering treatment line II to which there is an aerating and transport unit 7 connected. Two-stage dewatering treatment line II has two stages because it is only possible to obtain feeding product G from thin sludge C with low dry matter content after two consecutive dewatering procedures, which can then be added to intermediary product E produced on dewatering line I at the inlet of the aerating and transport unit 7. Also see Figure 2. According to the invention, it is essential that the mixing of feeding product G and intermediary product E in the inlet of aerating and transport unit 7 be implemented in a measured and controlled way so as to facilitate intervention.

The outlet of the equipment's other recipient unit 2 receiving sludge B of high dry matter content and that if the aerating and transport unit 7 suitable for achieving a 66- 99% dry matter content are connected to a mixing unit 8 where the basic product F appearing at the outlet of the aerating and transport unit 7 and sludge B appearing at the outlet of the recipient unit 2 is mixed in prescribed proportions, in a manner facilitating intervention, resulting in product H appearing at the outlet of the mixing unit 8. The outlet of the mixing unit 8 is connected to the final product production and granulating unit 9 which produces end product V that fulfils the desired specifications. The end product V can be fine or rough grained granulate or briquet.

In Figure 1 a thick bracket indicates the dewatering treatment line I and the two stage dewatering treatment line II. Dewatering treatment line I has a volume controlled sludge pump 4 that operates on the principle of volume displacement, a sewage sludge flow meter instrument 5 connected to it, and a dewatering unit 6 that operates on the principle of electro-osmosis. In order to pump sludge A, a lubricant additive D is added as necessary in order to reduce wear in the sludge pump 4 and the units downstream of it.

The two stage treatment line II possesses a pumping unit 10 suitable for pumping thin liquid sludge, a sewage flow meter 11, a pre-dewatering unit 12 and a dewatering unit

13 that operates on the principle of electro-osmosis. In order to operate the dewatering unit 13, flocculant P should be added as necessary. A settling tank fitted with fins 14 suitable for treating escapage is connected to dewatering treatment line I and the two stage dewatering treatment line II. Any escapage is directed from dewatering treatment line I and the two stage dewatering treatment line II to the settling tank fitted with fins

14 by drainage unit 1 k and drainage unit 2 q, respectively. For purposes of washing, water is fed back from the settling tank fitted with fins 14 to dewatering treatment line I via washing water line m. Wherever washing water is required in complex equipment, it is possible to obtain water from the settling tank fitted with fins 14 and brought there, however, this is not indicated separately in Figure 1. Any surplus water caught in the settling tank fitted with fins 14 is directed to the appropriate recipient via surplus water drain n. It is also a known fact that, with large closed loop equipment, the air used for aeration and drying must be filtered using a biofiltration apparatus before being released outside. The process subject to the invention has been partially dwelt upon when discussing Figure 1, which can be summarized as follows. Sewage sludge of types A, B and C is loaded into the corresponding recipient units 1, 2, 3 according to dry matter content. Sludge A is pumped onward into dewatering treatment line I. Here lubricant additive D is added and it is transferred by sludge pump 4 via flow meter instrument 5 to the dewatering unit 6 that operates on the principle of electro-osmosis, where it is dewatered. The volume of sludge passing through is controlled by the flow meter instrument 5, data is obtained for performing the other operations, and any technological intervention is made possible for producing the appropriate intermediary product E. The sludge is dewatered in dewatering unit 6, creating intermediary product E with a dry matter content of 50-66%.

Concurrently, the thin liquid sludge C is transferred from recipient unit 3 to the two stage dewatering treatment line II where the liquid sludge C is passed through a sewage flow meter 11 with the aid of pumping unit 10, the measurement results are continuously evaluated then, while adding flocculant P, the material is transferred to a pre-dewatering unit 12 in charge of the first dewatering stage, where it is pre-dewatered in view of the measurement results. The sludge obtained in the course of pre-dewatering is transferred to the dewatering unit 13 operating on the principle of electro-osmosis, representing the second dewatering stage, where it is dewatered even further and feeding product G is produced. Feeding product G is added to intermediary product E at the inlet of aerating and transport unit 7 in the quantity required then the resulting sludge mixture E & G is aerated, and the basic product F with a dry matter content of 66-99% thus obtained is transferred by conveyor to the mixing unit 8. During the treatment of sludge A and C, sludge B with a high dry matter content is intermittently or continuously received by the second recipient unit 2 and temporarily stored as necessary. Sludge B is mixed to basic product F in a predetermined proportion, or according to the operating or supervising personnel's intervention, in mixing unit 8 resulting in product H. Product H is transferred to the final product production and granulating unit 9 where end product V of the desired consistency and with the prescribed specifications is created, ready for transportation.

Figure 2 shows an embodiment example of the equipment subject to the invention shown in Figure 1, where the individual pieces of equipment are described in greater detail. It allows one to discern the individual pieces of the equipment and the preferred stages of the process more clearly and as part of the process. The two figures are easily compared based on the identical markings used.

The advantages of the equipment and process subject to the invention can be summarized as follows: The complex equipment subject to the invention is capable of continuously and simultaneously processing sewage sludge of varying dry matter content generated at communal sewage treatment facilities and which occasionally accumulates for processing or subsequent utilization. The recipient units of the equipment are suitable for the accommodation and buffer storage of sewage sludge of widely ranging dry matter content. By the constant control and management of the processing workflow it is possible to produce an end product with technical parameters that conforms best to an incineration plant's or furnace's specification and/or a customer's or user's requirements.

By employing the process subject to the invention, it is possible to create intermediary products of wide ranging properties, and to mix them whereby it is possible to create an end product with optimum technical parameters. An additional major advantage of the equipment and procedure subject to the invention is that it is environmentally friendly thanks to its closed loop design, it does not pollute the atmosphere, and it even recycles most of the waste water escapage.

Claims

1. A preferably closed-loop equipment for the continuous production of fuel from sewage sludge, which contains a dewatering unit operating on the principle of electro-osmosis, characterized in that it possesses at least three recipient units (1,

2, 3) suitable for the temporary storage of sludge with varying dry matter content, one of which, namely sludge A, has a dry matter content of 18-21%, the other sludge B has a dry matter content of 45-55%, and the third type, sludge C has a dry matter content of less than 6%, there is a dewatering treatment line (I) suitable for achieving a dry matter content of 50-66% connected to a recipient unit (1) for sludge A, there is an aerating and transport unit (7) connected to it, while there is another two stage dewatering treatment line (II) connected to the recipient unit (3) for sludge C to which there is likewise an aerating and transport unit (7) connected, furthermore, there is a mixing unit (8) connected to the other recipient unit (2) for sludge B and to the aerating and transport unit (7) suitable for achieving a dry matter content of 66-90%, while there is a final end product production and granulating unit (9) connected to the mixing unit (8).

2. The equipment described in Claim 1 characterized in that the dewatering treatment line (I) achieving a dry matter content of 50-66% has a volume controlled sludge pump (4) that operates on the principle of volume displacement, a sewage sludge flow meter instrument (5) connected to it, and a dewatering unit (6) that operates on the principle of electro-osmosis.

3. The equipment described in either Claim 1 or 2 characterized in that the two stage dewatering treatment line (II) connected to the recipient unit (3) for sludge C possesses a sludge pumping unit (10) suitable for pumping liquid sludge, a sewage flow meter (11), a pre-dewatering unit (12) and a dewatering unit (13) that operates on the principle of electro-osmosis.

4. The equipment described in any of Claims 1-3 characterized in that a settling tank fitted with fins (14) suitable for treating escapage is connected to dewatering treatment line (I) and the two stage dewatering treatment line (II).

5. Process for creating fuel from sewage sludge using the equipment described in Claim 1 characterized in that firstly the anaerobically and/or aerobically pretreated sludge available is transferred, according to its dry matter content, to at least three recipient units (1, 2, 3), so the first recipient unit (1) receives sludge A generated in the greatest volume and possessing a dry matter content of 18-21%, the second recipient unit (2) receives sludge B with a dry matter content of 40-55%, and the third recipient unit (3) receives liquid sludge C with a dry matter content of less than 6%, then sludge A is transferred to the dewatering treatment line (I) where sludge A is dewatered, resulting in an intermediary product E with a dry matter content of 50- 66%, liquid sludge C is concurrently transferred to the two stage dewatering treatment line (II) where sludge C is dewatered in two stages, resulting in feeding product G which is added to intermediary product E at the inlet of the aerating and transport unit (7) in the required quantity, then sludge mixture E+G is aerated, the basic product F with a dry matter content of 66-99% thus generated is transferred by conveyor to the mixing unit (8), while during the treatment of sludge A and C, the second recipient unit (2) is used to continuously receive, and temporarily store as necessary, sludge B with a high dry matter content, which is then mixed in a predetermined proportion and allowing intervention with basic product F in the mixing unit (8), creating product H which is then directed to the final product production and granulating unit (9) where end product V is created in the desired consistency, ready for transportation.

6. The process described in Claim 5 characterized in that dewatering sludge A is performed on dewatering treatment line (I) by first adding a lubricant additive D to sludge A, then sludge A is passed through a volume flow meter instrument (5) using a sludge pump (4), the measurement results are continuously evaluated, the sludge is transferred to a dewatering unit (6) that operates on the principle of electro-osmosis where it is dewatered using the measurement results to create intermediary product E with a dry matter content of 50-66%.

7. The process described in Claims 5-6 characterized in that the dewatering of liquid sludge C is performed in the two stage dewatering treatment line (II) by passing the liquid sludge C through a sewage flow meter (11) with the aid of pumping unit (10), the measurement results are continuously evaluated then, while adding flocculant P, the material is transferred to a pre-de watering unit (12) in charge of the first dewatering stage, where it is pre-dewatered in view of the measurement results then the sludge thus obtained is transferred to the dewatering unit (13) operating on the principle of electro-osmosis and representing the second dewatering stage where it is dewatered even further creating feeding product G.

8. The equipment described in any of Claims 5-7 characterized in that any escapage (sewage) generated on dewatering treatment line (I) and the two stage dewatering treatment line (II) is directed to a settling tank fitted with fins (14) where any sediment remaining is removed and the sewage thus cleaned is recycled in a closed loop so it is used for closed-loop washing.