scholarly journals Understanding conductivity and soda loss

TAPPI Journal ◽  
2017 ◽  
Vol 16 (02) ◽  
pp. 65-75 ◽  
Author(s):  
Michael Brown ◽  
Peter W. Hart
Keyword(s):  
Flow Control ◽  
Black Liquor ◽  
Sodium Content ◽  
Conductivity Measurements ◽  
Dilution Factor ◽  
System A ◽  
Concentration Changes ◽  
Last Stage ◽  
Inline Measurement ◽  
Expected Outcomes

For more than 40 years, conductivity has been the inline measurement of choice for inferring black liquor/soda losses from brownstock washing. If properly applied, conductivity can provide a benefit in tracking changes in black liquor filtrate concentration. The implied concentration changes in turn can be used to provide feedback for dilution factor or shower flow control on the last stage of a brownstock washing system. A further extrapolation of this application is the correlation (or lack of correlation) of conductivity to soda loss. For each type of conductivity-based application, there are fundamental principles and assumptions that must be understood and managed to achieve the expected outcomes. The fundamentals of conductivity, the application of conductivity to measure black liquor losses during brownstock washing, and laboratory considerations when attempting to correlate inline process conductivity to absolute sodium content are reviewed and investigated. Finally, the operational objectives and measurement alternatives for employing conductivity measurements are discussed.

scholarly journals Estimation of energy efficiency of kraft pulp production with the exergy increment method

2020 ◽  
Vol 22 (2) ◽  
pp. 3-11
Author(s):  
Р. V. Lukanin
Keyword(s):  
Energy Efficiency ◽  
Kraft Pulp ◽  
Black Liquor ◽  
High Energy ◽  
Kraft Pulping ◽  
Flue Gases ◽  
Flow Chart ◽  
Lime Kiln ◽  
System A ◽  
Recovery Boilers

This article contains results of exergic analysis of kraft pulping flow chart. The results of exergic balances of main kraft pulping processes such as alkali recovery at recovery boilers, black liquor evaporation, chips cooking, lime decarbonation are considered in details in the article. The analysis of the process flow chart makes it possible to determine the bottlenecks in the use of heat energy and to substantiate principal lines for increasing energy efficiency of the processes under study. A main share of the exergy expended in the existing pulping process is due to alkali recovery in the recovery boiler and comprises 70% of the total exergy available in the system. A procedure of hydrothermal production of chemicals in the process of kraft pulping is studied. A schematic diagram and analysis of heat technique of the kraft pulping process which in fact consists of organic component removal from black liquor through its autoclave carbonation with flue gases releasing from lime kiln at the temperature 80-90 oC are given in the article. The removal of organic components under these conditions can reach 70 %. In the studied version the exergic efficiency ηe = 80 % is considerably higher than that of the flow chart existing for chemicals recovery which is equal to ηe = 48 %. This is the evidence of high energy efficiency of the method developed.

Transport Properties of Type II Sodium-Silicon Clathrates

2005 ◽  
Vol 886 ◽  
Author(s):  
Matt Beekman ◽  
Jan Grkyo ◽  
George S. Nolas
Keyword(s):  
Thermal Conductivity ◽  
Sodium Content ◽  
Type I ◽  
Type Ii ◽  
Conductivity Measurements ◽  
Scanning Calorimetry ◽  
Resistivity Measurements ◽  
Silicon Clathrates ◽  
Covalently Bonded ◽  
First Time

ABSTRACTWe have synthesized the type II silicon clathrates Na1Si136 and Na8Si136, and report on the electrical and thermal transport in these materials. The crystal structure consists of a covalently bonded silicon framework in which sodium guest atoms are encapsulated inside the silicon host framework. Differential scanning calorimetry measurements show the compounds decompose above 600°C to diamond-structure silicon. Temperature dependant electrical resistivity measurements show the specimens to have an insulating character, with magnitudes that decrease with increasing sodium content. For the first time, thermal conductivity measurements on type II sodium-silicon clathrates are presented. The thermal conductivity is very low for both specimens, and for Na8Si136 exhibits a clear dip in the range from 50 to 70 K. These data suggest that the “rattling” behavior observed in type I clathrates may also be present in type II clathrates.

The Analyses of Lignin Structure and Molecular Weight Distributions of Small Fractions from Hardwood Dissolved Alkali Lignin

2012 ◽  
Vol 560-561 ◽  
pp. 595-599 ◽  
Author(s):  
Li Bin Dong ◽  
Yu Liu
Keyword(s):  
Molecular Weight ◽  
Functional Groups ◽  
Black Liquor ◽  
Gel Permeation Chromatography ◽  
Hydroxyl Group ◽  
Small Molecular Weight ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Last Stage ◽  
Set Up

The Soda-AQ cooking of poplar was carried out in the study. Acid-precipitation was used in the process of the classification and separation of lignin from the black liquor, and different lignin samples were obtained. The molecular weight distributions of lignin samples were analysed by GPC(gel permeation chromatography). The results showed that the last stage of the dissolved lignin sample had low molecular weight. The structure of lignin was analysed by 31P-NMR,and the content of the aliphatic hydroxyl group, phenolic hydroxyl group and other functional groups was obtained. According to the molecular weight and the content of functional groups, the structural diagrams of lignin fragments which had small molecular weight was set up.

scholarly journals Simulation study of mixed pressure and flow control systems for optimal operation of centrifugal pumping plants

2018 ◽  
Vol 14 (1) ◽  
pp. 89-94 ◽  
Author(s):  
Levon Gevorkov ◽  
Anton Rassõlkin ◽  
Ants Kallaste ◽  
Toomas Vaimann
Keyword(s):  
Flow Control ◽  
Pressure Control ◽  
Optimal Operation ◽  
Power Reduction ◽  
Point Of View ◽  
Power Calculation ◽  
Control Optimization ◽  
System A ◽  
Proposed Model ◽  
Series Of Experiments

Abstract A Simulink/DriveSize based model for the mutual pressure and flow control of a centrifugal pumping plant with a variable speed drive is proposed. The model provides the possibility of power calculation during both throttling and speed control and to estimate the optimal working point according to these calculations. The model is developed to provide the possibility of power reduction during pressure and flow maintenance with the help of mixed pressure control strategy. To evaluate the system, a series of experiments have been conducted. After the validation of the proposed model through testing, which proved that the designed system is more beneficial from the power consumption point of view than the traditional pressure control methods, it can be stated that the system is useful for pressure and flow control optimization of the centrifugal pumping plants

scholarly journals A transformation from temporal to ensemble coding in a model of piriform cortex

2017 ◽  
Author(s):  
Merav Stern ◽  
Kevin A. Bolding ◽  
L.F. Abbott ◽  
Kevin M. Franks
Keyword(s):  
Olfactory Bulb ◽  
Olfactory System ◽  
Feedback Inhibition ◽  
Piriform Cortex ◽  
Odor Coding ◽  
System A ◽  
Coding Strategies ◽  
Concentration Changes ◽  
Recurrent Collateral ◽  
The Impact

ABSTRACTDifferent coding strategies are used to represent odor information at various stages of the mammalian olfactory system. A temporal latency code represents odor identity in olfactory bulb (OB), but this temporal information is discarded in piriform cortex (PCx) where odor identity is instead encoded through ensemble membership. We developed a spiking PCx network model to understand how this transformation is implemented. In the model, the impact of OB inputs activated earliest after inhalation is amplified within PCx by diffuse recurrent collateral excitation, which then recruits strong, sustained feedback inhibition that suppresses the impact of later-responding glomeruli. Simultaneous OB-PCx recordings indicate that indeed, over a single sniff, the earliest-active OB inputs are most effective at driving PCx activity. We model increasing odor concentrations by decreasing glomerulus onset latencies while preserving their activation sequences. This produces a multiplexed cortical odor code in which activated ensembles are robust to concentration changes while concentration information is encoded through population synchrony. Our model demonstrates how PCx circuitry can implement multiplexed ensemble-identity/temporal-concentration odor coding.

NOx Control in Black Liquor Fuel Gas Combined Cycles

1996 ◽  
Author(s):  
Rebecca N. Sliger ◽  
Marcel D. Berz ◽  
John C. Kramlich ◽  
Philip C. Malte
Keyword(s):  
Gas Turbine ◽  
Black Liquor ◽  
Chemical Kinetic ◽  
Nox Emissions ◽  
Gas Combustion ◽  
Fuel Gas ◽  
Availability Analysis ◽  
System A ◽  
Combined Cycles ◽  
Nox Control

The gasification of black liquor, followed by its use in gas turbine engines, is an emerging alternative to the direct firing of the liquor in Tomlinson recovery boilers. Many gasification systems, however, convert the fuel nitrogen present in the liquor into ammonia (NH3) in the fuel gas, which leads to unacceptable NOx emissions in gas turbine combustors. This work uses detailed chemical kinetic modeling to examine the influence of two combustor modifications for the control of NOx emissions from black liquor fuel gas combustion. Availability analysis is also used to evaluate the influence of these NOx control choices on the thermodynamic architecture of the overall system. A rich-quench-lean configuration makes use of air staging. An alternative is to use a hot, rich external precombustor to remove NH3 before the main combustor. Here, the external, rich stage operates at around 30% theoretical air. Adiabatic temperatures are too low to obtain good NH3 reduction, so recuperative heating is necessary.

On-Chip Microdialysis System With In-Line Sensing Capabilities

2005 ◽  
Author(s):  
Yi-Cheng Hsieh ◽  
Jeffrey D. Zahn
Keyword(s):  
Glucose Sensor ◽  
Dead Volume ◽  
Step Response ◽  
System Response ◽  
Polycarbonate Membrane ◽  
Fluid Resistance ◽  
System A ◽  
Concentration Changes ◽  
On Chip ◽  
The Time Domain

Microdialysis probes have been used for diabetes treatment as continuous monitoring system coupled to a glucose sensor. An on-chip microdialysis system with in-line sensing electrodes is demonstrated. The response time of the microdialysis system was characterized and the permeability of the polycarbonate membrane (100nm pore size) to glucose was determined to be 2.53 μm/s (std:0.372 μm/s). As a first step towards greater biosensor integration with this miniaturized microdialysis system, a stacked system with in-line sensing electrodes was developed. Impedance electrodes within the microchannels were used to determine fluid resistance from a dialyzed phosphate buffered saline (PBS) solution, which characterizes solution conductivity as a function of PBS concentration. The permeability of the membrane to the salt ions was obtained as 0.74 μm/s (15 nm pores). Subsequently, experiments measuring PBS dialysis in the time-domain at 60% recovery were conducted. The PBS concentration of the reservoir was changed in either a step response or sinusoidally with an 800 second period. The subsequently measured impedance indicates that the system is able to continuously track concentration changes in the reservoir with a 180 second system response delay. Most of this delay is due to the dead volume within the tubing between the syringe pumps and the microsystem In addition the predicted response was modeled using linear systems theory and matches the experimental measurements. This system is expected to have the proper sensitivity to track physiologically relevant concentration changes of biomolecules such as glucose (which has a physiological maximum change rate of ~4mg/dL-min with a periodicity of 1 hour or greater) with minimal lag time and amplitude reduction.

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