Indian Patents. 202039:A METHOD AND A DEVICE FOR THE TREATMENT OF PULP WITH UREA AND AMMONIA

Title of Invention	A METHOD AND A DEVICE FOR THE TREATMENT OF PULP WITH UREA AND AMMONIA
Abstract	A method and a device for the treatment of pulp with urea and ammonia This invention relates to a method for the treatment of pulp with urea and ammonia, comprising: the treatment of pulp with urea and ammonia with a molar ratio of urea to pulp of 0.01 to 0.99:1 and a weight ratio of ammonia to pulp of 0.1 to 0.99:1.

Full Text	Method and device for the treatment of pulp with urea and ammonia The present invention relates to a method for the treatment of pulp with urea and ammonia, as well as to a device, which is particularly suited for performing the method. The ammonia treatment of pulp is necessary for activating the pulp so as to be able to carry out subsequent reaction steps, such as an acetylation, more easily. At the same time, an additive can be introduced into the pulp, namely to facilitate subsequent reaction steps. By doing so it is important that the introduction of the additive takes place as homogeneously as possible so as to obtain a homogeneous reaction product in the subsequent reaction steps. Such methods are known in the prior art. Thus, document DE-A-4329937 describes a method for the treatment of pulp for the activation thereof for subsequent chemical reactions, by bringing the pulp into contact with liquid ammonia at a pressure being increased over the atmospheric pressure. Ammonia is thereby preferably applied in a quantitative ratio ammonia to pulp of 6 to 10 mass units of ammonia to 10 mass units of pulp. The reaction with ammonia takes place in a pressure vessel. After a sufficient duration of action ammonia is expelled by opening the pressure vessel and by additional heating. Document EP-A-057 105 describes a method for producing an alkaline-soluble pulp derivative. Pulp is thereby treated with liquid ammonia, whereby the liquid ammonia contains dissolved urea. The method comprises the grinding of a pulp treated with alkali and neutralized with acetic acid with urea in a large amount of ammonia for 3 to 6 hours, whereby molar ratios of urea to pulp of 0.5 to 3 are used. The amount of ammonia as used approximately corresponds to 5 to 10 times the amount of pulp relative to the weight. Document WO-A-9947567 discloses a dosing method for mixtures of ammonia and an additive. A mixture of liquid ammonia and at least one additive is thereby produced first, and said mixture is subsequently fed to a solid substance to be treated. The production of the mixture and the addition of the mixture to the solid substance to be treated is thereby carried out twice, however, at different times, so that the ammonia additive system is practically continuously made available for the transmission to the solid substance. This international patent application also discloses the treatment of pulp with urea and ammonia, whereby 500 g urea are mixed with 4,000 g ammonia, which is then added to 2,000 g pulp in a preliminarily aranulated form DE 19628277, US 4404369 and DE 19835688 also deal with related subject matter. The known methods for the treatment of pulp with ammonia and urea have the disadvantage that a large amount of ammonia is used, with the result that the expenditure in view of the installation for expelling the quantities of ammonia, for recooling and reliquefying the ammonia and for producing the ammonia/urea mixture is considerable. Furthermore, the methods according to the prior art require a relatively long contact time for obtaining a sufficient saturation of the pulp with the mixture of ammonia and urea. This prolongs the time for the production of the pulp/urea mixture in an undesired manner, which, again, results in increased costs. At the same time, the expenditure in view of the costs for the required apparatus is great. Moreover, according to the known methods, disintegrated pulp materials, i.e. torn or grounded pulp samples are used for achieving a sufficient penetration of the pulp with the ammonia/urea mixture. For many methods it is. however, desirable to be able to treat not only defibrated or grounded puip, but pulp plates or webs with the mixture of ammonia and urea directly. It is, therefore, the object of the invention to provide a method for the treatment of pulp with urea and ammonia, in which the quantity of used ammonia and/or urea can be minimized, so that complicated apparatus and costs can be saved. Moreover, the method is to be suitable also for the treatment of pulp plates and/or pulp webs. At the same time, an impregnation of the pulp as homogeneous as possible should be achieved. Another object underlying the invention resides in providing a device with which especially the method according to the invention can be carried out. Said object is provided by a method for the treatment of pulp with urea and ammonia, comprising the treatment of pulp with urea and ammonia with a molar ratio of urea to pulp of 0.01 to 0.99:1 and a weight ratio of ammonia to pulp of 0.1 to 0.99:1. Accordingly, the present invention provides a method for the treatment of fine- fibered mass primarily consisting of pulp formed during the disintegration of wood and other plant materials comprising the step of impregnating said pulp with urea and ammonia with a molar ratio of urea to pulp of 0.01 to 0.99:1 and a weight ratio of Ammonia to pulp of 0.1 to 0.99:1. Accordingly, the present invention also provides a device for the treatment of pulp such as herein described by impregnation with ammonia and urea, comprising at least one pressure vessel and at least one application system provided therein wherein the at least one application system comprises a pair of application rollers or a pair of spraying nozzles. Moreover, the present invention provides a device for the treatment of pulp with urea and ammonia, comprising a pressure vessel and at least one application system provided therein. Description of the figures Figures 1 and 2 show embodiments of the device according to the invention, whereby the reference numbers designate the following elements: (1) vessel (recipient vessel) (1a) lid (2) shut-off device (3) vessel (reaction pressure vessel (4) shut-off device (5) vessel (deposit) (5a) lid (6} dosing pump CO dosing pump (8) application roll (9) application roll (10) fan (11) fan (12) heat exchanger (13) pulp plate (13a) pulp roll (14) roller conveyor (15) coil (15a) depositing device (16) heater (17) inlet (18) outlet (19) ammonia/urea (settling basin) (20) heating circuit (21) circuit Figure 1 shows a lateral view (section) of a device according to the invention for treating plate-type pulp- Figure 2 shows a lateral view (section) of a device according to the invention for the treatment of roll-type pulp. Figures 3 and 4 show preferred application systems of the invention, whereby figure 3 shows a pair of rollers (8, 9) and figure 4 shows a pair of spraying nozzles (8a, 9a). Detailed description of the invention The expression "treatment" as used in the present application stands for a method resulting in an impregnation of the pulp with ammonia and urea. According to the prior art such treatments are also called intercalation methods. All those terms will herein be used synonymously. The term "pulp" as used in the present application comprises the fine-fibered mass primarily consisting of pulp which is formed during the disintegration of wood or other plant fibers. The term comprises the types of pulp designated individually in accordance with their intended purpose of use, such as dissolving pulp, high alpha pulp or paper pulp, as well as the types of pulp designated according to the used disintegration methods or the used raw materials, such as sulfate pulp, dissolving and soda pulp as well as softwood pulp, hardwood pulp and fine straw pulp. The pulp to be treated in accordance with the present invention is preferably provided in the form of pulp plates, webs or rolls. When treating pulp with urea and ammonia according to the method according to the invention the weight ratio of ammonia to pulp is preferably 0.3 to 0.95:1, more preferably 0.5 to 0.9:1. The molar ratio of urea to pulp is preferably 0.1 to 0.95:1, more preferably 0.5 to 0.9:1. The method according to the invention is preferably carried out in an ammonia atmosphere. Especially preferred is an ammonia pressure of 5 to 25 bar. For this purpose the method according to the invention will be carried out in a pressure vessel. Such vessels are known to the skilled person. The treatment of pulp with ammonia and urea preferably takes place by using an ammonia/urea solution. Said solution preferably has a concentration of less than 99% of the saturation concentration, more preferably of less than 95% of the saturation concentration, relative to the saturation concentration of urea in ammonia. The lower limit is preferably at 10% of the saturation concentration. The method is preferably carried out at a temperature of 0 to 100°C, more preferably at 5 to 60T. The method according to the invention is characterized by the fact that an economical procedure without a great deal of operative efforts is possible due to the reduced quantity of urea and ammonia. According to particularly preferred embodiments the present invention moreover allows the treatment of pulp plates and/or pulp webs, so that complicated disintegration steps prior to the treatment of the pulp with ammonia and urea can be avoided and the treatment apparatus is substantially smaller and therefore more inexpensive. If, according to the inventive method, the pulp in the form of pulp plates, webs or rolls is treated, the ammonia and the urea are preferably applied in the form of a solution onto the pulp plates, webs or rolls to be treated, namely by using the device according to the invention with at least one application system as shown in figures 1 or 2. When treating pulp plates, webs or rolls, the method according to the invention is preferably structured such that the pulp plate treated last or, respectively, the portion of a pulp roll or web treated last is still left in the ammonia atmosphere for 0.5 to 30 minutes, preferably for 1 to 10 minutes, after it has passed through the application system according to the invention. Thus, it is assured also for the ultimately treated pulp material that the ammonia/urea mixture is homogeneously and evenly provided in the interior of the material. After the treatment according to the invention excessive ammonia may be removed. For this purpose the treated pulp can, for instance, be heated, a purge-gas flow may be used or a low pressure can be applied. Said process steps may be applied individually or in combination. The apparatus required therefor are known to the person skilled in the art. The device according to the invention will be described in the following. The device according to the invention comprises at least one pressure vessel. Such vessels are known to the skilled person. The device according to the invention moreover comprises at least one application system. Preferred examples of application systems according to the invention are one pair of rollers (8, 9) and one pair of spraying nozzles (8a, 9a). The device according to the invention comprises at least one application system, preferably one to three application systems, more preferably one application system. The application systems may thereby be identical or different. In front of the application system according to the invention a draw-in portion, if possible funnel-shaped, may be provided. This ensures a better guidance of the pulp materials to be treated prior to the passage through the application system. The device according to the invention especially preferably comprises one pair or two pairs of rollers (9, 8) as application systems. The specific configurations of such rollers are known to the skilled person, e.g. from the field of paper coating. The rollers of the above described application systems may likewise be equipped for transporting the materials passed therethrough, e.g. by hydraulic drives. In addition, the device may comprise a separate device for transporting the materials to be passed through, for example, a roller conveyor (14), preferably with hydraulically driven rollers, and a conveyor belt. If the material to be passed therethrough is, for instance, a rolled up web (13a), the separate conveying device may be constructed as coil (15) provided behind the application system. The material web is clamped into the same and is guided through the application system by a simple rotational movement. The device according to the invention preferably also comprises a dosing pump system (6, 7) by means of which, for instance, an ammonia/urea solution can be transported to the application system. Such dosing pump systems are known to the skilled person. The present invention will further be described with reference to the attached drawings. Preferred devices (figures 1, 2) substantially consist of three cylindrical pressure vessels (1, 3, 5) connected with each other by shutt-off devices (2, 4). Shut-off device (2) is optional. The shut-off devices are preferably constructed as wedge-type flat slide valves. Vessel (1) serves as receiver for the pulp to be treated, vessel (3) contains the application system and vessel (5) is the place of deposit for the treated pulp. Vessel (3) preferably comprises a heating (16) so as to allow the performance of pressure or temperature adjustments. Said heating is preferably constructed as half pipe heating. A conveying device (14), preferably a roller conveyor whereof the rollers are driven, for instance, hydraulically, passes from vessel (1) through vessel (3) into vessel (5). The pressure vessels are preferably made of precious steel VZA 1.4571 or similar materials. The at least one application system is disposed in vessel (3). The application system is preferably constructed as roller pair (8, 9) or spraying nozzle pair (8a, 9a). Said system preferably comprises at least one pair of application rollers (8, 9). Moreover, dosing pumps (6, 7) are provided in vessel (3). The specific construction of such dosing pumps is known to the skilled person. Vessel (5) comprises a depositing device (14a) or a wind-up unit (coil) (14) for receiving pulp materials. Vessel (5) is moreover connected to a heating circuit (20). Said circuit (20) comprises a fan (11) and a heat exchanger (12). Vessels (1) and (5) are further connected to a circuit (21) which comprises a fan (10). Vessel (3) is further connected with an inlet (17) and an outlet (18) constructed for charging and discharging the ammonia/urea solution. The device according to the invention is particularly suited for the performance of the method according to the invention. By the presence of the at least one application system an exact dosing of the ammonia and the urea as well as a good penetration of the pulp to be treated with the ammonia/urea mixture is achieved. The device according to the invention allows in particular also the treatment of pulp plates and/or pulp webs with ammonia and urea. The course of the treatment of pulp with ammonia and urea when using pulp plates or rolls and by applying the device according to the invention preferably is as follows. PI ate-type pulp (figure 1) Vessel (3) is insulated by the slides (2) and (4) and is subjected to an ammonia atmosphere. An ammonia/urea solution (in balance with the ammonia atmosphere) is provided in the settling basin (19) of vessel (3). Dosing pumps (6) and (7) as well as the pertaining circuits are filled with ammonia/urea solution. Vessels (1) and (5) are pressure-free and filled with air. The upper bumped boiler ends of both containers are designed as swivelling lids, which can be sealed fast and in a gas-proof manner by means of straining screws. Vessel (5) is closed, vessel (1) is open. The pulp plates are placed into vessel (1), whereupon the vessel is closed. Vessels (1) and (5) are now supplied with ammonia vapor from circuit (21) until the balance pressure of vessel (3) is reached. Slides (2) and (4) are opened. A sheet draw-in system, driven preferably hydradically, transports the sheets to the application rollers (8) and (9). When passing through the application rollers, the ammonia/urea solution is applied onto the pulp on both sides. The quantity to be applied is adjusted by the roller diameter and the dosing quantity of the pumps (6) and (7) in response to the pass-through rate. The sheets are then deposited in vessel (5) on the depositing device (15a). If the entire staple has passed through, slides (2) and (4) are closed. For drying purposes vessel (5) is either heated and/or evacuated Vessel (1) is evacuated, and the ammonia is fed to the reliquidification via circuit (21). Afterwards a re-rinsing with air takes place and the vessel can again be opened and charged. After the drying vessel (5) is set at an ambient pressure, whereby a substantial portion of the ammonia already evaporates. The heating circuit (20) is opened after that, and the fan (11) sucks the remaining ammonia out of vessel (5) and conveys the same via the heat exchanger (12), where it is heated to approximately 30 to 70°C, back into vessel (5) where the ammonia, which remained in the pulp, is expelled with the hot ammonia vapor. If the pulp has been dried up to a desired residual ammonia content the heating circuit (20) is shut off and locked off. Vessel (5) is thereupon completely evacuated. If necessary, the pulp can be left for a minute up to approximately 1 hour under a vacuum for degassing. Afterwards a brief re-rising with air takes place, and the treated pulp can be removed. Roll-type pulp ffiaure 2) The system and the procedure for roll-type pulp are similar to the ones described above, whereas no slide (2) is provided (see figure 2). The entire system is emptied and pressure-free, slide (4) is open. The pulp roll (13a) in hung into vessel (1), is threaded and passed through vessel (3) into vessel (5), where it is applied to coil (15) for winding it up. The system is closed and supplied with gaseous ammonia. The settling basin (19) of vessel (3) is afterwards filled with ammonia/urea solution via inlet (17). Pumps (6) and (7) start running and the pulp band is regularly drawn through the application rollers (8, 9). The dosing takes place as was described in connection with plate-type pulp. If the pulp is coiled up behind vessel (5), slide (4) is closed and the settling basin (19) of vessel (3) is emptied through the discharge (18) and the pump circuits. Afterwards vessels (1) and (3) are evacuated, rinsed with air and are ready for a new charge. The drying and degassing of vessel (5) takes place in correspondence with the treatment of pulp plates. According to the inventive method also the use of an application system comprising spraying nozzles (8a, 9a) is possible, which spray the urea to be applied onto the pulp, e.g. in the form of a solution. The nozzles may be provided both, above or underneath the pulp to be treated. The pulp materials to be treated are passed through between the application systems designed, for example, as roller pair (8, 9) or as spraying nozzle pair (8a, 9a). The ammonia and the urea are then applied onto the pulp by the application system. If the application system comprises, for instance, a pair of rollers, the application of the ammonia and urea onto the pulp can take place by transmitting said substances by the rollers onto the pulp during the passage through the roller pair. Independently of the type of application the method according to the invention configured in this manner effects a penetration of the pulp with the ammonia and the urea. If the application system comprises, for example, a pair of rollers, the rollers take care during the passage between the same that ammonia and urea are homogeneously applied onto the pulp to be treated in a thin film. The ammonia/urea solution then penetrates into the pulp plates, so that a good and homogeneous penetration is achieved. This results in an excellent intercalation and entails a largely homogeneous and, above all, complete transformation to carbamate in a subsequent transformation reaction. Due to the regular transformation it is thereby achieved that a well soluble and well processable product is obtained. The dosing of the quantity of ammonia and urea to be applied can take place during the performance of the inventive method by means of the inventive device, by controlling the dosing pumps (6, 7), the pass-through rate of the pulp plates (13) or webs, respectively, and/or the speed of the application rollers (8, 9). The devices and control techniques required therefor are known to the person skilled in the art. The treated pulp plates, webs or rolls may be freed from excessive ammonia after their treatment with ammonia and urea, namely by the above described methods. Afterwards they may directly be processed or stored or transported. WE CLAIM: 1. A method for the treatment of fine-fibered mass primarily consisting of pulp formed during the disintegration of wood and other plant materials comprising the step of impregnating said pulp with urea and ammonia with a molar ratio of urea to pulp of 0.01 to 0.99:] and a weight ratio of ammonia lo pulp of 0.1 to 0.99:1. 2. The method as claimed in claim 1, wherein the operating pressure of ammonia is 5 to 25 bar. 3. The method as claimed in claim 1 or 2, wherein the ammonia/urea solution has a concentration of 4. The method as claimed in at least one of the preceding claims, wherein the treatment of pulp with urea and ammonia takes place by applying urea and ammonia onto the pulp with at least one application system comprising a pair of rollers. 5. The method as claimed in at least one of the preceding claims, wherein pulp plates, webs or rolls are treated. 6. A device for the treatment of pulp such as herein described by impregnation with ammonia and urea, comprising at least one pressure vessel (3) and at least one application system provided therein wherein the at least one application system comprises a pair of application rollers (8, 9) or a pair of spraying nozzles (8a, 9a). 7. The device as claimed in claim 6, wherein a vessel (1) for providing the pulp to be treated and a vessel (5) for depositing the treated pulp are provided. 8. The device as claimed in claim 7, wherein the three vessels (1,3,5) are connected to each other via two shut-off means (2,4). 9. The device as claimed in claim 8, wherein the shut-off means (2,4) are wedge type flat slide valves sealing on two sides. 10. The device as claimed in at least one of the claims 6 to 9, wherein dosing pumps (6,7) for feeding ammonia/urea solutions to the at least one application system are provided. 11. A method for the treatment of fine-fibered mass substantially as herein described with reference to the accompanying drawings. 12. A device for the treatment of pulp substantially as herein described with reference to the accompanying drawings.

Full Text

Method and device for the treatment of pulp with urea and ammonia
The present invention relates to a method for the treatment of pulp with urea and ammonia, as well as to a device, which is particularly suited for performing the method.
The ammonia treatment of pulp is necessary for activating the pulp so as to be able to carry out subsequent reaction steps, such as an acetylation, more easily. At the same time, an additive can be introduced into the pulp, namely to facilitate subsequent reaction steps.
By doing so it is important that the introduction of the additive takes place as homogeneously as possible so as to obtain a homogeneous reaction product in the subsequent reaction steps. Such methods are known in the prior art.
Thus, document DE-A-4329937 describes a method for the treatment of pulp for the activation thereof for subsequent chemical reactions, by bringing the pulp into contact with liquid ammonia at a pressure being increased over the atmospheric pressure. Ammonia is thereby preferably applied in a quantitative ratio ammonia to pulp of 6 to 10 mass units of ammonia to 10 mass units of pulp. The reaction with ammonia takes place in a pressure vessel. After a sufficient duration of action ammonia is expelled by opening the pressure vessel and by additional heating.
Document EP-A-057 105 describes a method for producing an alkaline-soluble pulp derivative. Pulp is thereby treated with liquid ammonia, whereby the liquid ammonia contains dissolved urea. The method comprises the grinding of a pulp treated with alkali and neutralized with acetic acid with urea in a large amount of ammonia for 3 to 6 hours, whereby molar ratios of urea to pulp of 0.5 to 3 are used. The amount of ammonia as used approximately corresponds to 5 to 10 times the amount of pulp relative to the weight.
Document WO-A-9947567 discloses a dosing method for mixtures of ammonia and an additive. A mixture of liquid ammonia and at least one additive is thereby produced first, and said mixture is subsequently fed to a solid substance to be

treated. The production of the mixture and the addition of the mixture to the solid substance to be treated is thereby carried out twice, however, at different times, so that the ammonia additive system is practically continuously made available for the transmission to the solid substance. This international patent application also discloses the treatment of pulp with urea and ammonia, whereby 500 g urea are mixed with 4,000 g ammonia, which is then added to 2,000 g pulp in a preliminarily aranulated form DE 19628277, US 4404369 and DE 19835688 also deal with related
subject matter.
The known methods for the treatment of pulp with ammonia and urea have the disadvantage that a large amount of ammonia is used, with the result that the expenditure in view of the installation for expelling the quantities of ammonia, for recooling and reliquefying the ammonia and for producing the ammonia/urea mixture is considerable.
Furthermore, the methods according to the prior art require a relatively long contact time for obtaining a sufficient saturation of the pulp with the mixture of ammonia and urea. This prolongs the time for the production of the pulp/urea mixture in an undesired manner, which, again, results in increased costs. At the same time, the expenditure in view of the costs for the required apparatus is great. Moreover, according to the known methods, disintegrated pulp materials, i.e. torn or grounded pulp samples are used for achieving a sufficient penetration of the pulp with the ammonia/urea mixture. For many methods it is. however, desirable to be able to treat not only defibrated or grounded puip, but pulp plates or webs with the mixture of ammonia and urea directly.
It is, therefore, the object of the invention to provide a method for the treatment of pulp with urea and ammonia, in which the quantity of used ammonia and/or urea can be minimized, so that complicated apparatus and costs can be saved. Moreover, the method is to be suitable also for the treatment of pulp plates and/or pulp webs. At the same time, an impregnation of the pulp as homogeneous as possible should be achieved. Another object underlying the invention resides in providing a device with which especially the method according to the invention can be carried out.

Said object is provided by a method for the treatment of pulp with urea and ammonia,
comprising
the treatment of pulp with urea and ammonia with a molar ratio of urea to pulp of 0.01 to 0.99:1 and a weight ratio of ammonia to pulp of 0.1 to 0.99:1.
Accordingly, the present invention provides a method for the treatment of fine-
fibered mass primarily consisting of pulp formed during the disintegration of wood
and other plant materials comprising the step of impregnating said pulp with urea and
ammonia with a molar ratio of urea to pulp of 0.01 to 0.99:1 and a weight ratio of
Ammonia to pulp of 0.1 to 0.99:1.
Accordingly, the present invention also provides a device for the treatment of pulp such as herein described by impregnation with ammonia and urea, comprising at least one pressure vessel and at least one application system provided therein wherein the at least one application system comprises a pair of application rollers or a pair of spraying nozzles.

Moreover, the present invention provides a device for the treatment of pulp with urea and ammonia, comprising a pressure vessel and at least one application system provided therein.
Description of the figures
Figures 1 and 2 show embodiments of the device according to the invention, whereby the reference numbers designate the following elements:

(1) vessel (recipient vessel) (1a) lid
(2) shut-off device
(3) vessel (reaction pressure vessel
(4) shut-off device
(5) vessel (deposit) (5a) lid
(6} dosing pump
CO dosing pump
(8) application roll
(9) application roll
(10) fan
(11) fan
(12) heat exchanger
(13) pulp plate (13a) pulp roll
(14) roller conveyor
(15) coil (15a) depositing device
(16) heater
(17) inlet
(18) outlet
(19) ammonia/urea (settling basin)

(20) heating circuit
(21) circuit
Figure 1 shows a lateral view (section) of a device according to the invention for treating plate-type pulp- Figure 2 shows a lateral view (section) of a device according to the invention for the treatment of roll-type pulp. Figures 3 and 4 show preferred application systems of the invention, whereby figure 3 shows a pair of rollers (8, 9) and figure 4 shows a pair of spraying nozzles (8a, 9a).
Detailed description of the invention
The expression "treatment" as used in the present application stands for a method resulting in an impregnation of the pulp with ammonia and urea. According to the prior art such treatments are also called intercalation methods. All those terms will herein be used synonymously. The term "pulp" as used in the present application comprises the fine-fibered mass primarily consisting of pulp which is formed during the disintegration of wood or other plant fibers. The term comprises the types of pulp designated individually in accordance with their intended purpose of use, such as dissolving pulp, high alpha pulp or paper pulp, as well as the types of pulp designated according to the used disintegration methods or the used raw materials, such as sulfate pulp, dissolving and soda pulp as well as softwood pulp, hardwood pulp and fine straw pulp.
The pulp to be treated in accordance with the present invention is preferably provided in the form of pulp plates, webs or rolls.
When treating pulp with urea and ammonia according to the method according to the invention the weight ratio of ammonia to pulp is preferably 0.3 to 0.95:1, more preferably 0.5 to 0.9:1. The molar ratio of urea to pulp is preferably 0.1 to 0.95:1, more preferably 0.5 to 0.9:1.
The method according to the invention is preferably carried out in an ammonia atmosphere. Especially preferred is an ammonia pressure of 5 to 25 bar. For this

purpose the method according to the invention will be carried out in a pressure vessel. Such vessels are known to the skilled person.
The treatment of pulp with ammonia and urea preferably takes place by using an ammonia/urea solution. Said solution preferably has a concentration of less than 99% of the saturation concentration, more preferably of less than 95% of the saturation concentration, relative to the saturation concentration of urea in ammonia. The lower limit is preferably at 10% of the saturation concentration.
The method is preferably carried out at a temperature of 0 to 100°C, more preferably at 5 to 60T.
The method according to the invention is characterized by the fact that an economical procedure without a great deal of operative efforts is possible due to the reduced quantity of urea and ammonia. According to particularly preferred embodiments the present invention moreover allows the treatment of pulp plates and/or pulp webs, so that complicated disintegration steps prior to the treatment of the pulp with ammonia and urea can be avoided and the treatment apparatus is substantially smaller and therefore more inexpensive.
If, according to the inventive method, the pulp in the form of pulp plates, webs or rolls is treated, the ammonia and the urea are preferably applied in the form of a solution onto the pulp plates, webs or rolls to be treated, namely by using the device according to the invention with at least one application system as shown in figures 1 or 2.
When treating pulp plates, webs or rolls, the method according to the invention is preferably structured such that the pulp plate treated last or, respectively, the portion of a pulp roll or web treated last is still left in the ammonia atmosphere for 0.5 to 30 minutes, preferably for 1 to 10 minutes, after it has passed through the application system according to the invention. Thus, it is assured also for the ultimately treated pulp material that the ammonia/urea mixture is homogeneously and evenly provided in the interior of the material.

After the treatment according to the invention excessive ammonia may be removed. For this purpose the treated pulp can, for instance, be heated, a purge-gas flow may be used or a low pressure can be applied. Said process steps may be applied individually or in combination. The apparatus required therefor are known to the person skilled in the art.
The device according to the invention will be described in the following.
The device according to the invention comprises at least one pressure vessel. Such vessels are known to the skilled person.
The device according to the invention moreover comprises at least one application system. Preferred examples of application systems according to the invention are one pair of rollers (8, 9) and one pair of spraying nozzles (8a, 9a).
The device according to the invention comprises at least one application system, preferably one to three application systems, more preferably one application system. The application systems may thereby be identical or different.
In front of the application system according to the invention a draw-in portion, if possible funnel-shaped, may be provided. This ensures a better guidance of the pulp materials to be treated prior to the passage through the application system.
The device according to the invention especially preferably comprises one pair or two pairs of rollers (9, 8) as application systems. The specific configurations of such rollers are known to the skilled person, e.g. from the field of paper coating.
The rollers of the above described application systems may likewise be equipped for transporting the materials passed therethrough, e.g. by hydraulic drives.
In addition, the device may comprise a separate device for transporting the materials to be passed through, for example, a roller conveyor (14), preferably with hydraulically driven rollers, and a conveyor belt. If the material to be passed therethrough is, for instance, a rolled up web (13a), the separate conveying device

may be constructed as coil (15) provided behind the application system. The material web is clamped into the same and is guided through the application system by a simple rotational movement.
The device according to the invention preferably also comprises a dosing pump system (6, 7) by means of which, for instance, an ammonia/urea solution can be transported to the application system. Such dosing pump systems are known to the skilled person.
The present invention will further be described with reference to the attached drawings.
Preferred devices (figures 1, 2) substantially consist of three cylindrical pressure vessels (1, 3, 5) connected with each other by shutt-off devices (2, 4). Shut-off device
(2) is optional. The shut-off devices are preferably constructed as wedge-type flat slide valves. Vessel (1) serves as receiver for the pulp to be treated, vessel (3) contains the application system and vessel (5) is the place of deposit for the treated pulp. Vessel (3) preferably comprises a heating (16) so as to allow the performance of pressure or temperature adjustments. Said heating is preferably constructed as half pipe heating. A conveying device (14), preferably a roller conveyor whereof the rollers are driven, for instance, hydraulically, passes from vessel (1) through vessel
(3) into vessel (5). The pressure vessels are preferably made of precious steel VZA 1.4571 or similar materials.
The at least one application system is disposed in vessel (3). The application system is preferably constructed as roller pair (8, 9) or spraying nozzle pair (8a, 9a). Said system preferably comprises at least one pair of application rollers (8, 9). Moreover, dosing pumps (6, 7) are provided in vessel (3). The specific construction of such dosing pumps is known to the skilled person.
Vessel (5) comprises a depositing device (14a) or a wind-up unit (coil) (14) for receiving pulp materials.

Vessel (5) is moreover connected to a heating circuit (20). Said circuit (20) comprises a fan (11) and a heat exchanger (12).
Vessels (1) and (5) are further connected to a circuit (21) which comprises a fan (10). Vessel (3) is further connected with an inlet (17) and an outlet (18) constructed for charging and discharging the ammonia/urea solution.
The device according to the invention is particularly suited for the performance of the method according to the invention. By the presence of the at least one application system an exact dosing of the ammonia and the urea as well as a good penetration of the pulp to be treated with the ammonia/urea mixture is achieved. The device according to the invention allows in particular also the treatment of pulp plates and/or pulp webs with ammonia and urea.
The course of the treatment of pulp with ammonia and urea when using pulp plates or rolls and by applying the device according to the invention preferably is as follows.
PI ate-type pulp (figure 1)
Vessel (3) is insulated by the slides (2) and (4) and is subjected to an ammonia atmosphere. An ammonia/urea solution (in balance with the ammonia atmosphere) is provided in the settling basin (19) of vessel (3). Dosing pumps (6) and (7) as well as the pertaining circuits are filled with ammonia/urea solution. Vessels (1) and (5) are pressure-free and filled with air.
The upper bumped boiler ends of both containers are designed as swivelling lids, which can be sealed fast and in a gas-proof manner by means of straining screws. Vessel (5) is closed, vessel (1) is open. The pulp plates are placed into vessel (1), whereupon the vessel is closed. Vessels (1) and (5) are now supplied with ammonia vapor from circuit (21) until the balance pressure of vessel (3) is reached. Slides (2) and (4) are opened.
A sheet draw-in system, driven preferably hydradically, transports the sheets to the application rollers (8) and (9). When passing through the application rollers, the ammonia/urea solution is applied onto the pulp on both sides. The quantity to be

applied is adjusted by the roller diameter and the dosing quantity of the pumps (6) and (7) in response to the pass-through rate. The sheets are then deposited in vessel (5) on the depositing device (15a). If the entire staple has passed through, slides (2) and (4) are closed. For drying purposes vessel (5) is either heated and/or evacuated Vessel (1) is evacuated, and the ammonia is fed to the reliquidification via circuit (21). Afterwards a re-rinsing with air takes place and the vessel can again be opened and charged.
After the drying vessel (5) is set at an ambient pressure, whereby a substantial portion of the ammonia already evaporates. The heating circuit (20) is opened after that, and the fan (11) sucks the remaining ammonia out of vessel (5) and conveys the same via the heat exchanger (12), where it is heated to approximately 30 to 70°C, back into vessel (5) where the ammonia, which remained in the pulp, is expelled with the hot ammonia vapor. If the pulp has been dried up to a desired residual ammonia content the heating circuit (20) is shut off and locked off. Vessel (5) is thereupon completely evacuated. If necessary, the pulp can be left for a minute up to approximately 1 hour under a vacuum for degassing. Afterwards a brief re-rising with air takes place, and the treated pulp can be removed.
Roll-type pulp ffiaure 2)
The system and the procedure for roll-type pulp are similar to the ones described above, whereas no slide (2) is provided (see figure 2).
The entire system is emptied and pressure-free, slide (4) is open. The pulp roll (13a) in hung into vessel (1), is threaded and passed through vessel (3) into vessel (5), where it is applied to coil (15) for winding it up. The system is closed and supplied with gaseous ammonia. The settling basin (19) of vessel (3) is afterwards filled with ammonia/urea solution via inlet (17). Pumps (6) and (7) start running and the pulp band is regularly drawn through the application rollers (8, 9). The dosing takes place as was described in connection with plate-type pulp. If the pulp is coiled up behind vessel (5), slide (4) is closed and the settling basin (19) of vessel (3) is emptied through the discharge (18) and the pump circuits. Afterwards vessels (1) and (3) are

evacuated, rinsed with air and are ready for a new charge. The drying and degassing of vessel (5) takes place in correspondence with the treatment of pulp plates.
According to the inventive method also the use of an application system comprising spraying nozzles (8a, 9a) is possible, which spray the urea to be applied onto the pulp, e.g. in the form of a solution. The nozzles may be provided both, above or underneath the pulp to be treated. The pulp materials to be treated are passed through between the application systems designed, for example, as roller pair (8, 9) or as spraying nozzle pair (8a, 9a). The ammonia and the urea are then applied onto the pulp by the application system. If the application system comprises, for instance, a pair of rollers, the application of the ammonia and urea onto the pulp can take place by transmitting said substances by the rollers onto the pulp during the passage through the roller pair.
Independently of the type of application the method according to the invention configured in this manner effects a penetration of the pulp with the ammonia and the urea. If the application system comprises, for example, a pair of rollers, the rollers take care during the passage between the same that ammonia and urea are homogeneously applied onto the pulp to be treated in a thin film. The ammonia/urea solution then penetrates into the pulp plates, so that a good and homogeneous penetration is achieved. This results in an excellent intercalation and entails a largely homogeneous and, above all, complete transformation to carbamate in a subsequent transformation reaction. Due to the regular transformation it is thereby achieved that a well soluble and well processable product is obtained.
The dosing of the quantity of ammonia and urea to be applied can take place during the performance of the inventive method by means of the inventive device, by controlling the dosing pumps (6, 7), the pass-through rate of the pulp plates (13) or webs, respectively, and/or the speed of the application rollers (8, 9). The devices and control techniques required therefor are known to the person skilled in the art.
The treated pulp plates, webs or rolls may be freed from excessive ammonia after their treatment with ammonia and urea, namely by the above described methods. Afterwards they may directly be processed or stored or transported.

WE CLAIM:
1. A method for the treatment of fine-fibered mass primarily consisting of pulp formed during the disintegration of wood and other plant materials comprising the step of impregnating said pulp with urea and ammonia with a molar ratio of urea to pulp of 0.01 to 0.99:] and a weight ratio of ammonia lo pulp of 0.1 to 0.99:1.
2. The method as claimed in claim 1, wherein the operating pressure of ammonia is 5 to 25 bar.
3. The method as claimed in claim 1 or 2, wherein the ammonia/urea solution has a concentration of 4. The method as claimed in at least one of the preceding claims, wherein the treatment of pulp with urea and ammonia takes place by applying urea and ammonia onto the pulp with at least one application system comprising a pair of rollers.
5. The method as claimed in at least one of the preceding claims, wherein pulp plates, webs or rolls are treated.
6. A device for the treatment of pulp such as herein described by impregnation with ammonia and urea, comprising at least one pressure vessel (3) and at least one application system provided therein wherein the at least one application system comprises a pair of application rollers (8, 9) or a pair of spraying nozzles (8a, 9a).

7. The device as claimed in claim 6, wherein a vessel (1) for providing the pulp to be treated and a vessel (5) for depositing the treated pulp are provided.
8. The device as claimed in claim 7, wherein the three vessels (1,3,5) are connected to each other via two shut-off means (2,4).
9. The device as claimed in claim 8, wherein the shut-off means (2,4) are wedge type flat slide valves sealing on two sides.
10. The device as claimed in at least one of the claims 6 to 9, wherein dosing pumps (6,7) for feeding ammonia/urea solutions to the at least one application system are provided.
11. A method for the treatment of fine-fibered mass substantially as herein described with reference to the accompanying drawings.
12. A device for the treatment of pulp substantially as herein described with reference to the accompanying drawings.

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Patent Number

202039

Indian Patent Application Number

IN/PCT/2002/1872/CHE

PG Journal Number

30/2009

Publication Date

24-Jul-2009

Grant Date

Date of Filing

14-Nov-2002

Name of Patentee

ZIMMER AG

Applicant Address

BORSIGALLEE 1 60388 FRANKFURT AM MAIN.

Inventors:

#	Inventor's Name	Inventor's Address
1	WOLF REINHARD	LEIPZIGER STRASSE 2 63517 RODENBACH.

PCT International Classification Number

C08B15/06

PCT International Application Number

PCT/EP01/05271

PCT International Filing date

2001-05-09

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	100 23 753.3	2000-05-15	Germany