Pulp Mill Plant Research Articles

Modeling and Simulation of Pulp Mill Permanent Magnet Synchronous Machines with Damper Windings Using Matlab/Simulink

Modeling and simulation of pulp mill plant permanent magnet synchronous machines (PMSM) with damper windings using Matlab/Simulink is presented. Pulp mill is a manufacturing facility that converts wood chips, timber, wood products into wood pulp that is used to produce paper, cardboard, thick fiber board, which can be used by a paper mill for further processing. Pulp and paper industry has been considered a large consumer of energy and constitute a native treat to the plant as a result of machines transient due to heavy load variation. Modeling and simulation of pulp mill plant (PMSM) with damper windings show the behavior of machines virtual image environments to test the performance, stability and safety for less cost. It helps the pulp mill plant designers, engineers and technicians to understand the process of creating and analyzing machines model and predict its performance in the real world. Damper winding is an additional property added in pulp mill plant PMSM to damping out any oscillation that may cause any sudden changes in the load on the rotor when in synchronism. It prevents hunting and provides starting torque and dose not requires machines spinning. The rotor field lags the stator by which the load angle changes as a result of load variation. Permanent magnet synchronous machine (PMSM) is an alternating current (ac) machine whose excitation is provided by the permanent magnet. It has permanent magnet (PM) on the rotor and windings on the stator. PMSM does not have field windings on the stator frame instead, it relies on the magnets to provide the magnetic field against which the rotor interacts to produce a torque. Pulp mill plant PMSM with damper windings was modeling and simulated using Matlab/Simulink as presented in this paper. The electrical and mechanical equations of various steps ware developed in state space form from which the SIMULINK models were built with pulp mill plant PMSM with damper windings using the block-approach method with in-built Matlab/SIMULINK to obtained results for dynamics performance, controllability, stability study and is widely used in the engineering, manufacturing, physical sciences, product development and recommended for pulp mill plant designers, engineers, technicians and plant operators.

Transfer learning for process fault diagnosis: Knowledge transfer from simulation to physical processes

Deep learning has shown great promise in process fault diagnosis. However, due to the lack of sufficient labelled fault data, its application has been limited. This limitation may be overcome by using the data generated from computer simulations. In this study, we consider using simulated data to train deep neural network models. As there inevitably is model-process mismatch, we further apply transfer learning approach to reduce the discrepancies between the simulation and physical domains. This approach will allow the diagnostic knowledge contained in the computer simulation being applied to the physical process. To this end, a deep transfer learning network is designed by integrating the convolutional neural network and advanced domain adaptation techniques. Two case studies are used to illustrate the effectiveness of the proposed method for fault diagnosis: a continuously stirred tank reactor and the pulp mill plant benchmark problem.

A Comparison of Utility Heat Exchanger Network Synthesis for Total Site Heat Integration Methods

This paper compares Utility Heat Exchanger Network (UEN) design between two Total Site Heat Integration (TSHI) methods, the Conventional Total Site Targeting method (CTST) and the recently developed Unified Total Site Targeting (UTST) method. A large Kraft Pulp Mill plant has been chosen as a case study. Total Site targets have been calculated using a ExcelTM targeting spreadsheet and networks have been designed with the help of SupertagetTM for both the CTST and UTST methods. To achieve heat recovery and utility targets, both series and parallel utility heat exchanger matches for non-isothermal utilities are allowed in the CTST method, while series matches are allowed in the UTST method if the heat exchangers in series are from the same process. Series matches based on CTST method may create a dependency on two or more separate processes, which operational and control issues may occur, higher piping costs may be imposed, and utility target temperatures may not be achieved in the consecutive processes if one or more processes were to be out of service. Relaxation of the network can resolve these issues for the CTST method; however, if the relaxation occurs on the side of the utility loop that constrains heat recovery, the net heat recovery targets may not be achieved within the Total Site. The UTST method with its modified targeting procedure may offer slightly lower heat recovery targets but with simpler UEN design compared to CTST method are more realistic and achievable. Finally, after UEN design, non-isothermal utility loops need to be balanced in terms of mass and energy for both methods.

Atmospheric Dispersion Study of TRS Compounds Emitted from a Pulp Mill Plant in Coastal Regions of the Uruguay River, South America

ABSTRACTThe atmospheric dispersion of total reduced sulfur (TRS) emissions from the pulp mill plant of Fray Bentos, Uruguay is simulated. The local authorities of the Environmental Monitoring Program (EMP) of Gualeguaychu, Argentina, received social complaints of malodor presence in different places of the region. An atmospheric dispersion model coupled to a boundary layer forecast model is used to simulate 11 events in which the EMP officials attended the scene in order to verify the situation. The validation of modeled winds with the observations from a meteorological tower indicates reasonably accurate wind forecasts. The spatial layout of the modeled TRS plumes is compared with the geographical distribution of points in the area where the social complaints were recorded. Nine of the 11 studied events are successful modeling cases since a positive (negative) in situ verification matches with a plume position over (far from) the site. In one of the two unsuccessful modeling cases, although the plume is marginally distant from the site, the average wind direction error is the largest one of all the events. In the other case the modeled plume is in fact over the site, but the situation was negatively verified. The reason for the disagreement could be the wind direction changes during the event. This was the longest modeled case that lasted for 7 hours and the plume was meandering during that time; first from SSW to the S, then back the SSW, and finally to the S and SSE. The conclusion of the study is that, despite the inherent uncertainty of numerical simulations, the implemented modeling system shows versatility and proves to be a useful tool not only for diagnostic studies but also for preventing conflictive situations since it can produce reasonably accurate forecast of plume position and its potential impact.

Impact of a secondary treated bleached Kraft pulp mill effluent in both sexes of goldfish (Carassius auratus L.)

The aim of the present study was to assess the toxic effects of a secondary treated effluent from a modern pulp mill processing Eucalyptus globulus on both sexes of goldfish. The effects in the exposed fish were investigated by measuring biomarkers which have been used to assess the effects of BKME on aquatic biota, with particular emphasis in fish. However, few studies have been focused on effluents from pulp mill plants processing eucalyptus. The relative proportion of cytochrome P450 (CYP1A) and vitellogenin (VTG) induction were analyzed in the livers of males and females goldfish, exposed to different concentrations of a bleached Kraft pulp mill (BKPM) effluent. Somatic indices such as HSI (hepatosomatic index) and GSI (gonadosomatic index) were calculated and a significant reduction was found in males GSI. A significant increase of HSI was recorded for both sexes exposed to 50% BKPM effluent. Exposure to BKPM effluent induced CYP1A synthesis in both sexes and decreased VTG synthesis in females according to the different effluent concentrations suggesting that the secondary treated effluent contained compounds that affect fish negatively. The results suggest that BKPM effluent can cause sex-related biochemical changes in xenobiotic metabolism.

Improvements in Fault Tolerance Characteristics for Large Chemical Plants: 1. Waste Water Treatment Plant with Decentralized Control

A decentralized control scheme integrated with a recently developed fault detection, isolation, and estimation (FDIE) system applied on a benchmark of wastewater treatment plant (WWTP) is discussed here. This work belongs to a series whose objective is to demonstrate quantitatively the achievable improvements on the fault-tolerance characteristics supported by the integration with FDIE systems. In the previous work, a decentralized structure applied on a larger benchmark (such as the pulp mill plant) was presented. Specific aspects that are related to that case study were successfully handled by this methodology. Here, the WWTP presents new scenarios based on the occurrence of faults and their incidence on the associated dynamic with this process. In this work, faults such as extra dead time at actuators and bias and slow drifts in sensors (which, in some cases, can cause saturation), are analyzed. Under these conditions, a real need exists for turning the existent control scheme into a fault-tolerant (FT) scheme. This is done through reconfiguration of the controllers, using online identification and model-based control (MBC) tools. As the main contribution of this paper, a rigorous quantitative analysis is performed that takes account of a complete set of simulation cases, showing different scenarios. The accurate comparison study is given through several indexes associated with the WWTP benchmark, and others that are useful for analyzing the methodology are proposed here.

Activated sludge plants in Finland

The performance of Finnish activated sludge plants (primary clarifier, equalization basin, buffer basin, aeration basin, secondary clarifier and sludge handling) was surveyed. Performance was generally found to be excellent. BOD7 removal averaged 94% at paper mills (21mg/l effluent concentration, 0.43 kg/t discharge) and 95% at chemical pulp mills (18 mg/l, 0.83 kg/t). CODCr removal averaged 82% at paper mills (158 mg/l effluent concentration, 3.52 kg/t discharge) and 60% at pulp mills (531 mg/l, 20.7 kg/t). Treated effluent from paper mills contained 0.57 mg/l (13.3 g/t) of total phosphorus and from pulp mills 1.31 mg/l (47.3 g/t). AOX removal was 45-65% and discharge 0.15-0.90 kg/t. Suspended solids removal averaged 91% at paper mills and 76% at pulp mills, the average overflow concentration in primary clarifier being about 150 mg/l at both types of mill. All activated sludge plants are designed according to either the low load or extended aeration principle; high load plants are no longer in use. The average sludge load was 0.15 kg BOD/(kg MLSS d), the sludge age at the extended aeration plants ranging from 20 to 50 d. Low load appearance to be the main reason for the good performance of the plants. Other factors included the introduction of equalization and buffer basins at many plants, and particularly the fact that aeration factors and nutrients were under control. All paper mill activated sludge plants use nitrogen and phosphorus additions, whereas pulp mill plants manage without phosphorus. Optimization of nutrient addition is vital because almost every mill in Finland has a limit for its phosphorus discharge. Total sludge production at the paper mill plants averaged 40.9 t/d, 15% of which (5.9 t/d, 6.0 kg/t) was biosludge. At the pulp mills the figures were 27.2 t/d (11.5 t/d biosludge, 9.5 kg/tp). Belt filter presses are used for dewatering at most plants and dry solids contents are usually 25-35%. New-generation screw presses have been introduced, mainly at new pulp mill activated sludge plants, yielding dry solids contents of 40%. Combined and dewatered sludge is normally burned in bark-fired boilers, although some mills still landfill their sludge.

Activated sludge plants in Finland

The performance of Finnish activated sludge plants (primary clarifier, equalization basin, buffer basin, aeration basin, secondary clarifier and sludge handling) was surveyed. Performance was generally found to be excellent. BODE removal averaged 94% at paper mills (21mg/l effluent concentration, 0.43 kg/t discharge) and 95% at chemical pulp mills (18 mg/l, 0.83 kg/t). CODCr removal averaged 82% at paper mills (158 mg/1 effluent concentration, 3.52 kg/t discharge) and 60% at pulp mills (531 mg/l, 20.7 kg/t). Treated effluent from paper mills contained 0.57 mg/1 (13.3 g/t) of total phosphorus and from pulp mills 1.31 mg/l (47.3 g/t). AOX removal was 45–65% and discharge 0.15–0.90 kg/t. Suspended solids removal averaged 91 % at paper mills and 76% at pulp mills, the average overflow concentration in primary clarifier being about 150 mg/1 at both types of mill. All activated sludge plants are designed according to either the low load or extended aeration principle; high load plants are no longer in use. The average sludge load was 0.15 kg BOD/(kg MLSS d), the sludge age at the extended aeration plants ranging from 20 to 50 d. Low load appearance to be the main reason for the good performance of the plants. Other factors included the introduction of equalization and buffer basins at many plants, and particularly the fact that aeration factors and nutrients were under control. All paper mill activated sludge plants use nitrogen and phosphorus additions, whereas pulp mill plants manage without phosphorus. Optimization of nutrient addition is vital because almost every mill in Finland has a limit for its phosphorus discharge. Total sludge production at the paper mill plants averaged 40.9 t/d, 15% of which (5.9 t/d, 6.0 kg/t) was biosludge. At the pulp mills the figures were 27.2 t/d (11.5 t/d biosludge, 9.5 kg/tp). Belt filter presses are used for dewatering at most plants and dry solids contents are usually 25–35%. New-generation screw presses have been introduced, mainly at new pulp mill activated sludge plants, yielding dry solids contents of 40%. Combined and dewatered sludge is normally burned in bark-fired boilers, although some mills still landfill their sludge.

A trial of high performance anaerobic treatment on wastewater from a kraft pulp mill

In Japan Kraft pulp mill plants comprise 75% of pulp production. Attempts are described to treat wastewater from these plants by thermophilic anaerobic digestion of the evaporator condensate using a fixed-bed reactor packed with porous pumice stone and ultrafiltration membrane modules for microbial retention.