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In the past, oxygen delignification studies were mostly performed in batch reactors, whereby the caustic and dissolved oxygen concentrations are changing during the reaction. Also the lignin content and cellulose degradation of the pulp are only established at the end of an experiment when the sample is removed from the reactor.
The delignification reactor consists of an upflow pressurized vessel with a pulp distributor at the bottom and a pulp discharger at the top. The simulation was performed in 2D axissimetric and 3D geometry. The mesh created for the simulation of the geometries was the free triangular, being refined sequentially until obtaining different degrees .
that a closed cycle delignification system is feasible. EXPERIMENTAL All reactions were performed in a one liter Parr reactor. The contents were stirred using a turbine impeller at 140 RPM. Nitrogen was bubbled through the solution in the reactor for 15 minutes prior
anism by using a new kinetic reactor which allows XYGEN DELIGNIFICATION is widely used for lignin removal before bleaching. The well-known advantages of oxygen delignification are chemical cost sav-ings, yield retention and improved environmental performance. The disadvantages are the high capital cost and lower lignin-cellu-
The reactor was then immersed in an oil bath at 200 °C. It took 20 min for the reaction mixtures in the reactor to reach 200 °C. Subsequently, the reactor was kept in the oil bath for another 10 min, and the total heating time was 30 min. Afterwards, the reactor was removed and allowed to .
The second stage occurs in a larger reactor (residence time of 60 min), where the pressure is lower (3 bars) and the temperature is higher (90o-100o C).This provides the right elements to carry out the slower delignification stage.The longer residence time gives the proper volume to complete the slower stage of the delignification reac-
Jul 28, 2015 · Oxygen Delignification is one of the most significant and well proven pulp bleaching process for ECF (elemental chlorine free) and TCF (total chlorine free) bleached pulp production. It is the first stage of the bleaching process; in this case oxygen and alkali are used to eliminate a portion of the residual lignin in the pulp after cooking.
The delignification reactor consists of an upflow pressurized vessel with a pulp distributor at the bottom and a pulp discharger at the top. The simulation was performed in 2D axissimetric and 3D geometry. The mesh created for the simulation of the geometries was the free triangular, being refined sequentially until obtaining different degrees .
The delignification reactor consists of an upflow pressurized vessel with a pulp distributor at the bottom and a pulp discharger at the top. The simulation was performed in 2D axissimetric and 3D geometry. The mesh created for the simulation of the geometries was the free triangular, being refined sequentially until obtaining different degrees .
The delignification reactor consists of an upflow pressurized vessel with a pulp distributor at the bottom and a pulp discharger at the top. Oxygen delignification is the stage at which cellulosic pulp in an alkali solution, is pressurized with oxygen and steam, and then fed into the reactor. .
Oxygen delignification produces pulp with a higher yield than pulping to the same kappa number. Oxygen is generated by cryogenic air separation where it is separated from nitrogen and the other components in air. In a high consistency reactor, steam is added to pulp at the top of a downflow reactor. Course Details. Specs. Training Time: 17 minutes.
Pulp delignification in flow through reactor: The results obtained from pulp delignification in the flow through reactor were summarized in Table 1. The results showed that the global efficiency of ClO 2 in flow through reactor depended on the temperature and chlorine dioxide concentration used for delignification.
The kinetics of oxygen delignification and cellulose degrdn. of a high kappa softwood kraft pulp (kappa 65) are studied in a "flow-through" reactor where the pulp was held immobile within the reactor and a fresh oxygenated alk. soln. passes through the pulp mat at a set temp.
The delignification may vary in the range of 40-70% depending on the wood raw material and whether one or two reactors in series are used. Unbleached kraft (sulphate) pulp has a lignin content of 3-5%, which after oxygen delignification, can be decreased to about 1.5% or a kappa number of 8-10.
Oxygen delignification has historically been done using various concepts; in several ways, high consistency, medium consistency, one stage or two stages. The state of the art design today is the Kempulp DualOx ® system which offers better selectivity, lower bleach chemical consumption and possibilities to increase the cooking plant production.
The oxygen delignification reactor and experimental techniques have been described previously by Guven et al. (1996) and Agarwal (1999, 1997). The experiments were performed in a 2-liter, medium consistency oxygen reactor that was equipped with a mixer designed to approximate the low level of mixing in an oxygen up-flow tower (Figure A1).
The kinetics of oxygen delignification and cellulose degradation of a high kappa softwood Kraft pulp (kappa 65) are studied in a "flow-through" reactor where the pulp was held immobile within the reactor and a fresh oxygenated alkaline solution passes through the pulp mat at a set temperature. The feed solution maintains the alkali and dissolved oxygen concentration inside the pulp mat at .
Oxygen Delignification 2.1 Introduction 2.1.1. Comparison of Oxygen to Other Bleaching Agents 2.1.2. Advantages and Disadvantages of Oxygen Delignification . Reactor Inlet Distribution 13.3.4.2. Tower Dischargers 13.3.4.3. Reactor Blow Tank or Blow Tube 13.3.5. Reactor / Tower / Stock Tank Design 13.3.5.1. Pressurized Towers
The oxygen delignification reactor and experimental techniques have been described previously by Guven et al. (1996) and Agarwal (1999, 1997). The experiments were performed in a 2-liter, medium consistency oxygen reactor that was equipped with a mixer designed to approximate the low level of mixing in an oxygen up-flow tower (Figure A1).
(§63.441) does not specifically name reactor vents. Based on the data submitted to EPA following proposal (Air docket A-92-40, item IV-D1-29), the emissions from the oxygen delignification system reactor are vented through the system's blow tank; consequently, we did not name reactor vents in the oxygen delignification system definition.
Process parameters controlling the size of the reactor are the pulp throughput and consistency, temperature, caustic charge, oxygen addition rate and oxygen pressure. Design calculations suggest that the delignification rate depend strongly on the temperature while the selectivity is primarily controlled by the caustic addition.
Oxygen delignification (O-delignification) is an important tool for improving yield, reducing lignin content of pulp and lowering the bleach chemical consumption in the pulp and paper industries. This process is designed after cooking to maximize the delignification rate in comparison to the final phase of Kraft cooking without sacing pulp .
The oxygen delignification system is of the GL&V patented DUALOX type in two-reactors. The process was designed using reaction kinetic equations, which were translated into a mill context. The equations state that the oxygen delignification process proceeds via two different phases, a very rapid initial phase and a slow final phase.
Fast reactions, a short retention time (as a small reactor) is sufficient. Possibility of recycling filtrates to chemical recovery. Efficient delignification of all types of chemical pulps. Ozone was introduced as a bleaching chemical on industrial scale in the beginning of the 1990s.
Pulp delignification in flow through reactor: The results obtained from pulp delignification in the flow through reactor were summarized in Table 1. The results showed that the global efficiency of ClO 2 in flow through reactor depended on the temperature and chlorine dioxide concentration used for delignification.
Elemental Chlorine Free Delignification of Chemical Pulp in Flow Through Reactor: Yahya Hamzeh, Soheila Izadyar and Gerard Mortha: Abstract: Based on the known mechanisms of lignin degradation by ClO 2, it has been shown that in conventional ECF delignification stage a significant part of applied chlorine dioxide is consumed in secondary reactions without significant effect on beaching.
oxygen delignification reactor where delignification reactions occur during a flow-through lasting about one hour. Efficient gas-liquid mass transfer is important for oxygen delignification .
single reactor. Hardwood pulp needs two reactors if a kappa number reduction of over 35% is required. Table 1 shows typical conditions in oxygen delignification. Table 1. Conditions in oxygen delignification. First stage Second stage temperature (°C) 80 - 85 90 - 105 pressure (bar) 7 - 10 3 - 5 retention time (min) 20 - 40 60 - 80 Valves
In the past, oxygen delignification studies were mostly performed in batch reactors, whereby the caustic and dissolved oxygen concentrations are changing during the reaction. Also the lignin content and cellulose degradation of the pulp are only established at the end of an experiment when the sample is removed from the reactor.
Oxygen delignification A laboratory inclined Parr reactor was used in this study at constant oxygen pressure (1,034 kPa) and consistency (12 %). The mixer speed was kept constant at 20 rpm. The Parr reactor was warmed up to 70 °C. The reactor was then charged with pulp sample (60.00 g o.d.), 0.5 % MgSO4 (5 % w/w solution,