Briquetting press and method for operating a briquetting press

Abstract

The invention relates to a briquetting press in the form of a hot briquetting press for producing hot-briquetted iron, comprising a first press roller (1a) and a second press roller (1b) which are driven so as to rotate in opposite directions and the roller surfaces of which are each equipped with briquette troughs (4) for producing briquettes (B), wherein material (M) can be applied to the roller gap (5) formed between the two press rollers (1a, 1b) and can be pressed in the roller gap (5) to form briquettes (B) or a briquette strand. The first press roller (1a) is connected to a first electric motor drive (8a) and driven, and the second press roller (1b) is connected to a second electric motor drive (8b) and driven, and the two electric motor drives (8a, 8b) are synchronised in such a way that the briquette troughs (4) of the two press rollers (1a, 1b) lying opposite one another in the roller gap (5) are aligned congruently to each other during operation.

Description

[0001] Briquetting press and method for operating a briquetting press

[0002] Description:

[0003] The invention relates to a briquetting press in the embodiment as a hot briquetting press for the production of hot briquetted iron, with two press rollers, i.e. a first press roller (briquetting roller) and a second press roller (briquetting roller), which are driven in counter-rotation and whose roller surfaces are each equipped with briquette troughs for producing briquettes, wherein material is fed onto the roller gap formed between the two press rollers and can be pressed or is pressed in the roller gap to form briquettes or a briquette strand.

[0004] The two press rollers, i.e. the first press roller and the second press roller, are generally mounted in a press frame (i.e. press stand) so that they can rotate and are driven. Preferably, one of the press rollers is designed as a fixed roller and the other press roller as a loose roller, wherein the loose roller is movable relative to the fixed roller, namely displaceable against the fixed roller with a variable gap width and is therefore adjustable. For this purpose, the loose roller is displaceable / adjustable against the fixed roller via force generating means, e.g. hydraulically and / or pneumatically. It is preferably provided that at least one of the press rollers, in particular the loose roller (or alternatively both rollers), is mounted in the press stand so that it can be moved at an angle in order to allow an inclined position of at least one of the press rollers relative to the other press roller.

[0005] To produce briquettes with such a briquetting press, the roller surfaces are provided with briquette troughs. The rollers can be designed as solid rollers with briquette troughs directly embedded in the surfaces. Alternatively, the press roller itself can have a

[0006]

[0007] A roller core (with shaft) and, on the other hand, a ring band arranged on the roller core, with the briquette troughs arranged on the ring band. Alternatively, several segments can be arranged on a roller core as briquetting tools with the briquette troughs. As a rule, each of the briquette troughs forms half of the briquette shape of the briquettes to be produced, so that a briquette is formed in the roller gap by two briquette troughs facing each other. To ensure perfect briquette quality, it is necessary that the briquette troughs are brought into exact registration with one another during operation and are therefore precisely aligned with one another.

[0008] In practice, this has so far been achieved by driving the two briquetting rollers with a single, shared electric motor, namely via a double-shaft gearbox with two output shafts connected to the press roller shafts via compensating couplings. This design has proven extremely successful in practice, as the drive with a single electric motor and the mechanical coupling of the rollers with a double-shaft gearbox ensure precisely synchronous rotation of the two briquetting rollers. However, this requires an adjustment of the two roller surfaces to each other during commissioning, which is essentially carried out once using mechanical means and can be relatively complex.Tests are typically conducted during commissioning to verify the precise overlap of the troughs on the two rollers. Further adjustments are made iteratively if necessary to ensure perfect alignment. Once this is achieved, flawless operation and the production of high-quality briquettes can be achieved with the help of the single drive and the double-shaft gear. The briquetting presses known from the state of the art with

[0009] A common drive and double-shaft gear unit are suitable not only for the briquetting of cold material (e.g., steel mill residues) but also, in particular, for the briquetting of directly reduced iron and consequently for the production of hot briquetted iron (HBI). During the production of HBI, the material is fed into the roll gap at high temperatures of approximately 700°C. The press rolls are generally cooled to prevent excessive heating of the briquetting tools and the press roll bearings. Impairment of the double-shaft gear unit was not a concern in conventional systems, as the double-shaft gear units are connected to the press rolls via relatively long compensating couplings.

[0010] A briquetting press of the type described above is known, for example, from DE 967 207, in which the two briquetting rollers are driven synchronously by a common drive via an upstream double-shaft gear unit connected to the rollers by intermediate shafts. At least two couplings of the two intermediate shafts are designed as toothed couplings with different numbers of teeth.

[0011] Alternatively, briquetting presses with hydraulic drives are known from the prior art. For example, US Pat. No. 3,765,173 A describes a briquetting press in which the two briquetting rollers are each driven by individual, synchronized hydraulic drives.

[0012] A similar design of a briquetting press with individual hydraulic drives is described in UA 13572 U.

[0013] DE 1 075 486 discloses a roller briquette press equipped with two drive motors for the two rollers. The synchronization

[0014] The rollers are rotated by meshing gears.

[0015] Another embodiment of a roller press is described in DE 10 2013 109 405 A1.

[0016] Further embodiments of briquette presses with synchronously driven press rollers are known from JP 2006-097435 A and DE 10 2020 114 835 A1.

[0017] DE 19 76 527 U describes a roller press for compacting or producing briquettes, pressed granules, or other pressed products. A plug-in gearbox is mounted on each of the drive pins of the press rollers. Electric motors are mounted on the housings of the plug-in gearboxes, which drive the rollers via V-belt drives.

[0018] Roller presses designed not for briquetting, but for crushing or compacting material, are equipped with individual electric motor drives. This is readily possible with roller presses designed especially as high-pressure roller mills, because precise synchronization of the press rollers is not required for crushing material (e.g., cement clinker) or compacting (e.g., fertilizer).

[0019] A compacting press in which the compacting rollers are driven by individual drives is known, for example, from DE 102 10 307 C1.

[0020] CN 103962199 A discloses a roller press for crushing material with individually driven crushing rollers.

[0021]

[0022] WO 2023 / 086002 A1 also describes a device for producing hot-briquetted iron using a hot-briquetting press.

[0023] A device for briquetting hot material is also known from CN 210079458 U. This also describes measures for cooling various components of the system. The same applies to CN 202274072 U.

[0024] Finally, EP 2 874 805 B1 discloses a roller press for briquetting, compacting or grinding granular material, in which the press rollers are equipped with cooling devices.

[0025] Based on the prior art, the invention seeks to create a briquetting press characterized by an optimized drive concept. The briquetting press is intended, in particular, to enable the production of high-quality briquettes economically and with simple commissioning of the roller press.

[0026] To achieve this object, the invention teaches, in a briquetting press of the type described above, that the first press roller is connected to and driven by a first electric motor drive, and the second press roller is connected to and driven by a second electric motor drive, and that the two electric drives (of the two press rollers) are synchronized such that the briquette troughs of the two press rollers, located opposite each other in the roller gap, are (exactly) aligned with each other during operation. The briquette troughs of the two press rollers, located opposite each other in the roller gap, are precisely aligned with each other when the press is started up.

[0027]

[0028] The invention is based on the finding that in a briquetting press, the two pressing rollers can be driven by individual electric motor drives if suitable control and preferably also monitoring of the pressing rollers and / or drives ensures suitable synchronization such that the briquette troughs on the roller surfaces are and remain permanently aligned during operation, thus producing briquettes of impeccable quality. This makes it possible, in particular, to dispense with the need for a complex double-shaft gear, since each of the two rollers has its own electric motor drive. Since modern electric motor drives with frequency converters are now available at low cost and enable variable and precisely controllable operation of the pressing rollers, the briquetting press with individual drives can be manufactured and operated particularly economically.Especially the commissioning and, consequently, the initial adjustment of the two press rollers to each other or their surfaces can be achieved quickly and easily thanks to suitable electronic control. This will be discussed in more detail below.

[0029] Preferably, the electric motor drive is connected to the first press roller via a first gear unit, e.g., a first planetary gear unit (as a reduction gear unit), e.g., mounted directly thereon. The second electric motor drive is connected to the second press roller via a second gear unit, e.g., a second planetary gear unit (e.g., a reduction gear unit), e.g., mounted directly thereon. The two gear units enable a flawless transmission of high torques to the press rollers, with a separate gear unit being used for each electric motor drive and, consequently, each press roller.

[0030] Furthermore, it is advisable to drive the first electric motor via a

[0031] connect the first compensating coupling to the first press roller and connect the second electric motor drive to the second press roller via a second compensating coupling. These compensating couplings facilitate the connection of the electric motor drives to the gearboxes and serve, for example, to compensate for angles in the event of tilting and / or displacement of one or both rollers. They can, for example, each be designed as cardan joints or cardan joint couplings in order to enable, in particular, relative movements of the press rollers to one another, e.g., tilting of one press roller relative to the other press roller and, moreover, also relative movement due to a changing roller gap. These compensating couplings are preferably provided between the respective electric motor drive and the associated gearbox.

[0032] Optionally or additionally, the first electric motor drive can be connected to the first press roller via a first safety clutch, and the second electric motor drive can be connected to the second press roller via a second safety clutch. The safety clutches serve to quickly and reliably mechanically separate the electric motor from the gearbox if a torque preset on the clutch is exceeded. This prevents overloads and subsequent damage to the drive trains of the briquetting machine or the briquetting machine itself. Such overloads could occur, for example, if a large solid object in the fed material enters the roller gap, causing the machine to suddenly brake or lock.Preferably, the safety couplings are arranged between the electric motor drive and the respective transmission, particularly preferably between the drive and the aforementioned compensating coupling, if such a compensating coupling is provided.

[0033]

[0034] In a particularly preferred embodiment, each of the two drive trains for the two press rollers thus comprises the electric motor drive, the safety clutch, the compensating clutch, and finally the gear, e.g., a planetary gear, in the same way, starting from the drive and ending at the press roller in the described order.

[0035] Of particular importance is the precisely synchronous operation of the two briquetting rollers, achieved through suitable control of the two electric motor drives, each driven, for example, by a variable-speed frequency converter to ensure precise electronic synchronization. To this end, it is advisable for each drive to be equipped with a measuring device that measures and monitors the angular position of the motor shaft of the respective electric motor drive. The two electric motor drives are preferably controlled based on the signals generated by these two measuring devices. Angle encoders assigned to the respective motor shaft (output shaft of the motor) are particularly suitable as measuring devices for the angle function.The angle encoders allow the exact angular position of the respective motor shaft to be determined continuously during operation, thus achieving the desired synchronization of the two press rollers electronically and consequently bringing and maintaining the briquette troughs in alignment.

[0036] Alternatively or additionally, it may be expedient to provide measuring devices in the area of ​​the press rollers themselves and thus each roller measuring device with which the rotational angle position of the respective press roller can be determined or at least a zero position of the respective press roller can be determined. Such a roller measuring device for determining a so-called zero position can, for example, be implemented in such a way that each of the two

[0037]

[0038] Each press roller is equipped with a reference marking, which interacts with at least one sensor that is stationary, e.g., on a press frame. Sensors that can be used include proximity sensors that operate magnetically, optically, or capacitively, e.g., Hall sensors, light barriers, or the like. Determining the roller position itself or determining a zero position can be useful or necessary because, due to the intermediate gears, the position of the motor shaft is related to a variety of angular positions of the roller. It is therefore advantageous to supply the control system with information about a defined zero position of the press rollers. A measuring device for determining a zero position of the respective press roller is particularly advantageous for commissioning the system and for initial adjustment of the two press rollers relative to one another.What is interesting is that during commissioning, no mechanical adjustment of the briquette troughs to each other is required, but that the entire adjustment can be carried out electronically via the control of the drives, taking into account the respective measurement results.

[0039] The two electric motor drives are preferably each designed as asynchronous electric motors. Furthermore, it is preferably provided that the electric motor drives are driven by frequency converters with variable speeds.

[0040] In one embodiment of the invention, it is provided that the two electric motor drives are connected to a (common) control and are controllable, wherein the speed of one or both electric motor drives for synchronizing the press rollers can be varied separately and independently of each other, preferably depending on input signals which determine the angular position of the motor shafts and / or the

[0041]

[0042] Represent the angular position of the press rollers, e.g. depending on the signals of the two rotary encoders and / or the signals of the proximity sensors.

[0043] According to the invention, the briquetting press is designed as a hot briquetting press and is therefore designed for the processing of directly reduced iron (DRI) and / or the production of hot briquetted iron (HBI).

[0044] The press rollers of the briquetting press, specifically the hot briquetting press, are each equipped with one or more cooling devices. This can be roller cooling in the sense of internal cooling, where, for example, the roller core is cooled via a core bore. Alternatively or additionally, the bandage of the press roller or the segments of the press roller can be cooled with the briquetting tools. In this case, known cooling devices for hot briquetting presses or other presses are used. While in conventional systems the cooling of the press rollers primarily serves to protect the bearings and, if necessary, the briquetting tools themselves, the invention provides that the briquetting press is cooled with suitable cooling devices, with the proviso that the transmissions of the drive train are heated to a maximum temperature below a predetermined limit temperature.The invention is based on the realization that the inventive concept with individual drives and, in particular, with interposed individual gears can be used advantageously even when processing warm or hot feed material and consequently at higher or even extremely high temperatures of, for example, more than 600°C. Surprisingly, a flawless integration of individual drives into a briquetting press, namely a hot briquetting press, is achieved without causing damage or impairment to the drive components and, in particular, the

[0045]

[0046] Gearboxes are to be feared, although the gears in the drive train according to the invention are preferably arranged directly near the press rollers themselves. The cooling devices are designed and / or configured in such a way that heat input into the gears is minimized. If necessary, the gears can optionally be connected to the press rollers with the interposition of additional measures, e.g., the interposition of heat shields.

[0047] Known findings and designs can be used for the cooling devices for the briquetting press. The press rollers themselves can be equipped with cooling devices, e.g., cooling devices that cool the roller core and / or the roller surfaces or briquette troughs. This can, for example, involve cooling the ring bands or the tool segments. The focus is always on cooling the rollers themselves. Alternatively or additionally, the bearing housings of the press rollers are preferably cooled and thus provided with cooling devices. This is because the press rollers are each rotatably mounted, for example, with their shaft journals in bearing housings, whereby the bearing housings are arranged, for example, in a fixed or movable manner in the press frame. Alternatively or additionally, the gears themselves can also be cooled, e.g., via the gear oil circulating in the gears, which can be equipped with an oil cooling system.One, several, or all of these cooling devices are preferably designed and / or operated in such a way that specified limit temperatures of, for example, 120°C in or on the gearboxes are not exceeded. A limit temperature can be, for example, the shaft temperature of the gearbox's output shaft, since this output shaft is equipped with seals designed for a maximum temperature. This output shaft of the gearbox is generally connected directly or indirectly to the press roller, e.g., the shaft journal of the press roller.

[0048]

[0049] The output shaft of the gearbox can, for example, be designed as a hollow shaft that is pushed or plugged onto the roll journal / shaft journal of the press roll. In any case, cooling takes place via the cooling devices described, with the proviso that the shaft temperature of the wear shaft of the gearbox does not exceed a limit temperature of, for example, 120 °C, preferably 100 °C. In addition, it is optionally ensured that the temperature inside the gearbox, e.g. the bearing temperatures of the bearings within the gearbox, does not exceed a limit temperature, e.g. a limit temperature of 120 °C. Alternatively or additionally, it is optionally ensured that the oil temperature of the gearbox oil in the gearbox does not exceed a maximum temperature, e.g. a maximum temperature of 110 °C, preferably a maximum temperature of 100 °C.

[0050] Overall, the invention enables particularly quick and easy commissioning and synchronization, which can be carried out, for example, by the plant operator themselves. The basic design of the press draws on familiar components and knowledge from the field of high-pressure roller mills. A particular advantage is cost savings, particularly for large machines. Despite the potentially higher costs for two smaller individual drives compared to a larger combined drive, and the potential costs for frequency converters (and an additional cardan shaft), the overall costs are reduced primarily by dispensing with the relatively complex double-shaft gearbox and the curved-tooth couplings between the double-shaft gearbox and the rollers that are standard in the state of the art.

[0051] The invention relates not only to the briquetting press described, but also

[0052] A method for operating such a briquetting press. The method is characterized in that the first press roller is driven by a first electric motor drive and the second press roller is driven by a second electric motor drive, wherein the two electric motor drives are (electronically) synchronized such that the briquette troughs of the two press rollers, which are opposite one another in the roller gap, are aligned and remain aligned with one another during operation. For this purpose, the rotational angle positions of the two press rollers can be monitored with rotary encoders, and the drives can be controlled in an electronically synchronized manner depending on the signals. The method according to the invention is particularly preferably used for processing directly reduced iron at a temperature of more than 600°C, e.g. at least 700°C, which is pressed into hot briquettes (HBI) in the roller gap of the hot briquetting press.

[0053] The hot briquetting press is always operated in such a way that the gears of the drive rod, which according to the invention are preferably directly connected to the press rollers, do not exceed the described limit temperatures.

[0054] The invention is explained in more detail below with reference to drawings, which represent only one exemplary embodiment. They show:

[0055] Fig. 1 shows a briquetting press according to the invention in a perspective view,

[0056] Fig. 2 schematically simplifies the briquetting process with a briquetting press,

[0057]

[0058] Fig. 3 shows a section of the press according to Fig. 1 in the area of ​​a measuring device on a briquetting roller,

[0059] Fig. 4 a cross-section through a press roller of a briquetting press with cooling device.

[0060] The figures show a briquetting press and consequently a high-pressure roller press for briquetting (granular) material M. The roller press has two press rollers 1a, 1b and consequently a first press roller 1a and a second press roller 1b, which are rotatably mounted in bearing housings 21a, 21b and driven to rotate in opposite directions. The bearing housings 21a, 21b are in turn mounted stationary or displaceably in a press frame 2, which is also referred to as a press frame. The roller surfaces of the two briquetting rollers 1a, 1b are each equipped with briquette troughs 4 for producing briquettes B. As a rule, one of the press rollers, e.g. the first press roller 1a, is designed as a fixed roller and is rotatably mounted stationary in the press frame 2. One of the press rollers, e.g. B. the second press roller 1b can be designed as a so-called loose roller, ie it is displaceable relative to the fixed roller and, if necessary, tiltable.The floating roll can therefore be adjusted against the fixed roll with a variable width of the roll gap 5. For this purpose, one of the rolls, e.g., roll 1b as a floating roll, can be adjusted against the fixed roll using force-generating means, e.g., hydraulic cylinders 6, and can be displaced within the press frame or press stand 2 (see Fig. 1).

[0061] During operation of the briquetting press, the material M is fed to the roller gap 5 via a feed screw 7 or other feeding means and pressed in the roller gap 5 into briquettes B or a briquette strand (see Fig. 2).

[0062]

[0063] Fig. 1 shows that, according to the invention, the two press rollers 1a, 1b are driven by individual electric motor drives. The first press roller 1a is connected to and driven by a first electric motor drive 8a. The second press roller 1b is connected to and driven by a separate, second drive 8b. To produce briquettes of impeccable quality, the two electric motor drives 8a, 8b are synchronized according to the invention such that the briquette troughs 4 of the two press rollers, which are opposite one another in the roller gap 5, are aligned with one another during operation. This will be discussed further below.

[0064] In the exemplary embodiment, the first electric motor drive 8a is connected to the first press roller 1a via a first gear 9a, e.g., a planetary gear. The second electric motor drive 8b is connected to the second press roller 1b via a second gear 9b, e.g., a reduction gear. In the example, the gears 9a, 9b are mounted on the shaft ends or shaft journals of the briquetting rollers 1a, 1b and are designed, for example, as planetary gears. Consequently, no further transmission elements for the high torques present there, e.g., curved-tooth couplings or the like, are required or provided between the gears 9a, 9b and the shaft journals of the rollers.

[0065] It can also be seen that a first compensating clutch 10a and / or a first safety clutch 11a are optionally provided between the first electric motor drive 8a and the first transmission 9a. A second compensating clutch 10b and / or a second safety clutch 11b are optionally provided between the second electric motor drive 8b and the second transmission 9b. Each of the two drive trains consists, in the preferred embodiment, of the electric motor drive 8a, 8b, the safety clutch 11a, 11b, the

[0066]

[0067] Compensating couplings 10a, 10b and the gears 9a, 9b (see Fig. 1). The compensating couplings 10a, 10b ensure that one or both rollers can be tilted and / or moved relative to each other.

[0068] Of particular importance is the synchronous operation of the two briquetting rollers 1a, 1b, namely by suitable control of the two electric motors 8a, 8b, which can be, for example, asynchronous motors operated exactly synchronously by means of frequency converters via a common control system.

[0069] To ensure synchronous operation of the two drives 8a, 8b and to control them as desired, it is advisable to equip the drives 8a, 8b themselves with measuring devices, e.g., with rotary encoders assigned to the respective motor shaft. The rotary encoders can be used to determine the exact angular position of the respective motor shaft at any time, thus ensuring precise synchronous operation. Details are not shown in the figures.

[0070] In addition, the illustrated embodiment provides that the two rollers 1a, 1b are also equipped with measuring devices, in particular to be able to determine a zero position of the respective roller. For this purpose, the two press rollers 1a, 1b are each equipped with a reference marking 12, which can be attached, for example, in the area of ​​the shaft or a roller core of the respective roller 1a, 1b. This reference marking 12 corresponds to the angular position of the briquette troughs on the briquetting roller. A corresponding sensor, e.g., a proximity sensor 13, is arranged on the press frame 2 and interacts with the reference marking 12. This can be a magnetic or optical sensor. Details are not shown. In any case,

[0071] This device allows a zero position for each press roller to be defined and transferred to the control system. This ensures, during commissioning and subsequent adjustment, that the briquette troughs 4 of the two press rollers 1a, 1b are precisely aligned to produce briquettes B of impeccable quality. Adjustment can be performed electronically. After adjustment, synchronous operation can be ensured solely through the precise control and monitoring of the two drives 8a, 8b, taking into account the integrated rotary encoders.

[0072] Preferably, the press rollers 1a, 1b are provided with cooling devices that are configured and operated in such a way that the drive train, and in particular the gears 9a, 9b of the drive train, which are mounted directly on the ends of the briquetting rollers 1a, 1b, for example, without intermediary elements, are heated to a maximum temperature below a predetermined limit temperature. When designing the briquetting press, e.g., its press rollers with cooling devices, generally known knowledge can be used, since cooling devices for briquetting presses, e.g., their briquetting rollers, are known and common. Thus, the briquetting press in the illustrated embodiment can be designed with cooling devices for the press rollers 1a, 1b and / or cooling devices for the bearing housings 21a, 21b and / or cooling devices for the gear oil circulating in the gears 9a, 9b.According to the invention, however, cooling is carried out with the proviso that the specially designed drive train of the individual drives, and in particular the gears 9a, 9b, are not excessively heated and thereby subjected to stress or damage. The cooling is therefore not designed solely or only to protect the rollers 1a, 1b and their bearings, but also, in particular, to protect the drive train, which is the primary objective of the invention.

[0073]

[0074] One possible cooling device for a press roll is shown in Fig. 4. In this case, reference can be made, for example, to the findings of EP 2 874 805 B1. The press roll 1 a, 1 b can, for example, have a roll core 15 and a bandage 14, wherein the bandage 14 can, for example, be shrunk onto the roll core 15. The bandage 14 is equipped with the briquette troughs 4. The roll is equipped with a liquid cooling system, e.g. water cooling. For this purpose, a plurality of axially parallel cooling channels 16 distributed over the circumference are integrated into the bandage 14 below the bandage surface. The axially parallel cooling channels 16 are connected to an axial central channel 18 in the roll core 15 via radially running inlet and outlet channels 17. This central channel 18 is connected to a liquid inlet and a liquid outlet via a suitable rotary union.The cooling medium can be distributed via two distribution rings 19, each connected to the front of the drum, with, for example, deflection channels 20. Details are known from EP 2 874 805 B1. In principle, however, other types of cooling known from the prior art are also possible.

[0075] Alternatively or in addition to cooling the roll core 15 and / or the bandage 14 or corresponding tool segments, cooling of the bearing housings 21a, 21b can be provided. Details are not shown in the figures. For example, cooling channels through which a liquid coolant, e.g., water, flows can be integrated into the bearing housings.

[0076] The briquetting press described is designed as a hot briquetting press, ie it is used to process hot material M, in particular directly reduced iron (DRI), which is fed to the roller gap 5 at a high feed temperature of, for example, 700 °C or more. Cooling is particularly important in such a hot briquetting press, so that

[0077] According to the invention, the cooling devices are operated in such a way that the described limit temperatures in the area of ​​the gear unit are not exceeded. In principle, however, such cooling is also advantageous for other types of briquetting presses or briquetting presses for processing other materials.

Claims

Patent claims:

1. Briquetting press in the embodiment as a hot briquetting press for the production of hot briquetted iron, with a first press roller (1a) and a second press roller (1b), which are driven in opposite rotation and whose roller surfaces are each equipped with briquette troughs (4) for producing briquettes (B), wherein material (M) can be fed onto the roller gap (5) formed between the two press rollers (1a, 1b) and pressed in the roller gap (5) to form briquettes (B) or a briquette strand, characterized in that the first press roller (1a) is connected to and driven by a first electric motor drive (8a) and the second press roller (1b) is connected to and driven by a second electric motor drive (8b) and that the two electric motor drives (8a, 8b) are synchronized in such a way that the briquette troughs (4) of the two press rollers (1a,1 b) are aligned with each other during operation., 2. Briquetting press according to claim 1, characterized in that the first electric motor drive (8a) is connected to the first press roller (1a) via a first gear (9a), e.g. a first planetary gear, and the second electric motor drive (8b) is connected to the second press roller (1b) via a second gear (9b), e.g. a second planetary gear.

3. Briquetting press according to claim 1 or 2, characterized in that the the first electromotive drive (8a) is connected to the first press roller (1a) via a first compensating coupling (10a) and the second electromotive drive (8b) is connected to the second press roller (1b) via a second compensating coupling (10b), wherein the compensating couplings (10a, 10b) are designed, for example, as cardan joints and / or are preferably arranged between the respective drive (8a, 8b) and the associated gears (9a, 9b).

4. Briquetting press according to one of claims 1 to 3, characterized in that the first electric motor drive (8a) is connected to the first press roller (1a) via a first safety coupling (11a) and the second electric motor drive (8b) is connected to the second press roller (1b) via a second safety coupling (11b), wherein the safety couplings (11a, 11b) are preferably arranged between the respective drive (8a, 8b) and the associated gear (9a, 9b), e.g. between the respective drive (8a, 8b) and the compensating coupling (10a, 10b).

5. Briquetting press according to one of claims 1 to 4, characterized in that the first drive (8a) and the second drive (8b) are each equipped with a measuring device with which the rotational angle position of the shaft of the respective drive can be measured and that the two drives can preferably be controlled as a function of signals generated by the measuring devices.

6. Briquetting press according to claim 5, characterized in that the measuring devices associated with the electric motor drives (8a, 8b) are designed as rotary angle sensors, which are associated, for example, with the respective motor shaft.

7. Briquetting press according to one of claims 1 to 6, characterized in that the first press roller (1a) and the second press roller (1b) are each assigned a roller measuring device (12, 13) with which the rotational angle position of the respective press roller and / or a zero position of the press roller can be measured and that the two electromotive drives (8a, 8b) are preferably controllable as a function of signals generated by the roller measuring devices.

8. Briquetting press according to one of claims 1 to 7, characterized in that the press rollers are each equipped with a reference marking (12) representing the relative angular position of the briquette troughs, which reference markings each interact with at least one sensor (13) arranged in a fixed position, e.g. on a press frame (2), wherein the sensors are designed, e.g. as proximity sensors, e.g. as magnetic or optical sensors.

9. Briquetting press according to one of claims 1 to 8, characterized in that the two electric motor drives (8a, 8b) are connected to a common control and are controllable, wherein the speed of one or both electric motor drives for synchronizing the press rollers can be varied separately and independently of the other drive, preferably as a function of input signals representing the angular position of the motor shafts and / or the angular position and / or a zero position of the press rollers, e.g. as a function of the signals of the two rotary encoders and / or the signals of the proximity sensors.

10. Briquetting press according to one of claims 1 to 9, characterized in that the electromotive drives (8a, 8b) are each designed as electric asynchronous motors and / or that the electromotive Drives can be driven using frequency converters with variable speed.

11. Briquetting press according to one of claims 1 to 10, with one or more cooling devices, characterized in that the cooling devices are designed to cool the briquetting press in such a way that the transmissions of the drive train are heated to a maximum temperature below a predetermined limit temperature.

12. Briquetting press according to claim 11, wherein the briquetting press has one or more cooling devices for cooling the press rollers and / or one or more cooling devices for cooling bearing housings in which the press rollers are rotatably mounted, characterized in that the cooling devices of the press rollers and / or the cooling devices of the bearing housings are designed to cool the press rollers and / or the bearing journals of the press rollers rotatably mounted in the bearing housings in such a way that the gears (9a, 9b) of the drive train are heated to a maximum temperature below a limit temperature.

13. Briquetting press according to claim 11 or 12, wherein the gears (9a, 9b) are equipped with cooling devices for cooling the gear oil guided or circulating in the gears.

14. Briquetting press according to one of claims 11 to 13, characterized in that the cooling devices of the press rollers and / or the bearing housings and / or the oil circulation are cooled in such a way that the shaft temperature of an output shaft of the gearbox does not exceed a first limit temperature of, for example, 100 °C and / or that the gearbox temperature, e.g. the bearing temperatures within one or both gearboxes, does not exceed a second limit temperature of, for example, 120 °C. and / or that the oil temperature of the transmission oil does not exceed a third limit temperature of, for example, 110 °C.

15. Briquetting press according to one of claims 1 to 14, characterized in that the gears (9a, 9b) are connected to the press rollers with the interposition of heat shields.

16. A method for operating a briquetting press according to one of claims 1 to 15, characterized in that the first press roller (1a) is driven by a first electric motor drive (8a) and the second press roller (1b) is driven by a second electric motor drive (8b) and that the two electric motor drives (8a, 8b) are synchronized in such a way that the briquette troughs (4) of the two press rollers, which are opposite one another in the roller gap (5), are aligned in register with one another during operation.

17. Method according to claim 16, characterized in that the rotational angle position of the two press rollers (1a, 1b) and / or the rotational angle function of the motor shafts of the electric motor drives (8a, 8b) is monitored and that the electric motor drives are controlled in an electronically synchronized manner as a function of the signals.

18. Method according to claim 17, characterized in that the electric motor drives (8a, 8b) are controlled as a function of rotational angle positions of the two motor shafts of the electric motor drives, which are monitored by angle sensors assigned to the motor shafts.

19. Method according to one of claims 16 to 18, characterized in that the briquetting press, e.g. its press rollers and / or the bearing housings and / or the gear oil, are cooled with the proviso that the gears (9a, 9b) of the drive train are heated to a maximum temperature below a predetermined limit temperature.

20. Method according to claim 19, characterized in that the press rollers and / or the bearing housings and / or the gear oil are cooled with the proviso that the shaft temperature of the output shafts of the gearboxes does not exceed a first limit temperature of, for example, 100 °C and / or that the bearing temperature of the gearbox bearings within the gearbox does not exceed a second limit temperature of, for example, 120 °C and / or that the oil temperature of the gearbox oil in the gearboxes does not exceed a third limit temperature of, for example, 110 °C.

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