Factors affecting particulate removal efficiency of kraft recovery boiler electrostatic precipitators: a technical review

TAPPI Journal ◽  
2018 ◽  
Vol 17 (05) ◽  
pp. 273-283 ◽  
Author(s):  
Ezzat Jaroudi ◽  
Ivan Sretenovic ◽  
Greg Evans ◽  
Honghi Tran
Keyword(s):  
Particle Size ◽  
Sodium Chloride ◽  
Collection Efficiency ◽  
Operating Conditions ◽  
Pulp Mills ◽  
Factors Affecting ◽  
Recovery Boilers ◽  
Electrostatic Precipitators ◽  
Recovery Boiler ◽  
Particulate Removal

Electrostatic precipitators (ESPs) are used in most pulp mills to remove particulate from recovery boilers, power boilers, and lime kilns. As environmental regulations have become increasingly stringent in recent years, maintaining high ESP performance is of vital importance in mill operation. This paper discusses results of a literature review of the ESP technology used in industrial combustion units, including recovery boilers, as well as results of a parametric study using the well-known Deutsch-Anderson equation to correlate recovery boiler operating conditions with ESP collection efficiency. The results show that for particles up to about 0.3 μm, the ESP collection efficiency decreases drastically with increased particle size and with decreased temperature. For particles larger than 0.5 μm, however, the trend reverses; the collection efficiency increases with increased particle size and decreased temperature. The results also suggest that the particle concentration (or loading) in the flue gas has no effect on collection efficiency and that sodium chloride particles are more readily captured than sodium sulfate particles. The latter prediction, however, appears to be in contradiction with mill experience that sodium chloride particles are more difficult to capture.

Factors affecting the electrical resistivity of kraft recovery boiler precipitator ash

TAPPI Journal ◽  
2014 ◽  
Vol 13 (7) ◽  
pp. 31-39 ◽  
Author(s):  
IVAN SRETENOVIC ◽  
MASOUMEH FARKHONDEHKAVAKI ◽  
MARK KORTSCHOT ◽  
HONGHI TRAN
Keyword(s):  
Electrical Resistivity ◽  
Chloride Content ◽  
High Resistivity ◽  
Pulp Mills ◽  
Electrical Field Strength ◽  
Factors Affecting ◽  
Sulfur Dioxide Concentration ◽  
Recovery Boilers ◽  
Electrostatic Precipitators ◽  
Recovery Boiler

The electrical resistivity of ash particles is an important parameter that determines the efficiency of electrostatic precipitators. This systematic study examines the resistivity of recovery boiler precipitator ash as a function of electrical field strength, time of exposure, particle composition, and gas composition and temperature. Synthetic ash and actual ash samples from several pulp mills are used. The results show that most ash samples tested had a resistivity between 109 and 1010 Ω·cm, but one of the samples had an unusually high resistivity, 1012 Ω·cm. The resistivity increases with temperature up to about 140°C, then decreases. At a given temperature, the resistivity decreases with increasing moisture and sulfur dioxide concentration in the gas. Resistivity also increases with an increase in chloride content in the ash, but is not affected by the carbonate, sulfate, and potassium contents. The results imply that recovery boilers burning liquors with high solids and high chloride contents produce ash with higher resistivity, making it more difficult for electrostatic precipitators to capture.

New learnings and strategies for meeting future recovery boiler particulate emission limits with existing electrostatic precipitators

TAPPI Journal ◽  
2021 ◽  
Vol 20 (6) ◽  
pp. 405-412
Author(s):  
IVAN SRETENOVIC
Keyword(s):  
Electrostatic Precipitator ◽  
Practical Experience ◽  
The United States ◽  
Operating Conditions ◽  
Particulate Emission ◽  
Process Simulations ◽  
Electrostatic Precipitators ◽  
Recovery Boiler ◽  
Emission Limits ◽  
Efficiency And Reliability

It is foreseeable that recovery boiler particulate emission limits in the United States and Canada will continue to get more stringent with time. Because of this, continued improvement of emission control equipment, as well as a better understanding of how operating parameters affect performance, are necessary. Although electrostatic precipitators (ESPs) are often viewed as a mature technology, many improvements in ESP technology continue to be developed. In recent years, academic efforts have improved the understanding of recovery boiler operating conditions on ESP performance. Additionally, advancements in materials, power supplies, and design continue to improve the efficiency and reliability of ESPs. This paper discusses how recovery boiler and electrostatic precipitator (ESP) operating factors affect ESP performance based on process simulations and practical experience, and how these learnings can be implemented to improve future operation of existing ESPs.

Implications of converting a kraft pulp mill to a dissolving pulp operation with a hemicellulose extraction stage

TAPPI Journal ◽  
2013 ◽  
Vol 12 (2) ◽  
pp. 29-38 ◽  
Author(s):  
ENRIQUE MATEOS-ESPEJEL ◽  
THEODORE RADIOTIS ◽  
NACEUR JEMAA
Keyword(s):  
Kraft Pulp ◽  
Paper Industry ◽  
Production Capacity ◽  
Pulp Mill ◽  
Dissolving Pulp ◽  
Operating Conditions ◽  
Pulp Mills ◽  
Kraft Pulp Mill ◽  
Efficiency Measures ◽  
Recovery Boiler

Global demand for dissolving pulp has been increasing at a remarkable pace over the last few years. A shortage in cotton and the expansion of the textile, hygiene, and health product markets are behind this booming demand. The Canadian pulp and paper industry has entered these markets by converting several paper-grade pulp mills to dissolving pulp producers. In the kraft process, part of the hemicellulose remains with the pulp after cooking and the rest is burnt in the recovery boiler to produce energy. In dissolving pulp mills, most of the hemicellulose must be removed from the wood chips in a pre-hydrolysis stage before pulping. Hemicellulose hydrolysis and its subsequent extraction will affect energy and chemical balances. In addition, the new operation will require large capital expenditures. The objective of this work was to study the conversion of a kraft pulp mill to a dissolving pulp operation and the extraction of hemicelluloses from the process. The effects of hemicellulose extraction on mill energy balance, equipment requirements, and new operating conditions were analyzed. Computer simulations of the process and thermal pinch analysis were used. The existing bottlenecks (digesters, lime kiln, and recovery boiler) to increasing the dissolving pulp production capacity were identified before and after the conversion. In addition, energy efficiency measures were identified to decrease the energy consumption of the new process.

Recovery boiler sootblowers: History and technological advances

TAPPI Journal ◽  
2015 ◽  
Vol 14 (1) ◽  
pp. 51-60
Author(s):  
HONGHI TRAN ◽  
DANNY TANDRA
Keyword(s):  
Cfd Modeling ◽  
Computing Systems ◽  
The Past ◽  
Technological Advances ◽  
Recovery Boilers ◽  
Computational Fluid Dynamics Cfd ◽  
Recovery Boiler ◽  
Steam Parameters ◽  
Insight Into ◽  
Deposit Removal

Sootblowing technology used in recovery boilers originated from that used in coal-fired boilers. It started with manual cleaning with hand lancing and hand blowing, and evolved slowly into online sootblowing using retractable sootblowers. Since 1991, intensive research and development has focused on sootblowing jet fundamentals and deposit removal in recovery boilers. The results have provided much insight into sootblower jet hydrodynamics, how a sootblower jet interacts with tubes and deposits, and factors influencing its deposit removal efficiency, and have led to two important innovations: fully-expanded sootblower nozzles that are used in virtually all recovery boilers today, and the low pressure sootblowing technology that has been implemented in several new recovery boilers. The availability of powerful computing systems, superfast microprocessors and data acquisition systems, and versatile computational fluid dynamics (CFD) modeling capability in the past two decades has also contributed greatly to the advancement of sootblowing technology. High quality infrared inspection cameras have enabled mills to inspect the deposit buildup conditions in the boiler during operation, and helped identify problems with sootblower lance swinging and superheater platens and boiler bank tube vibrations. As the recovery boiler firing capacity and steam parameters have increased markedly in recent years, sootblowers have become larger and longer, and this can present a challenge in terms of both sootblower design and operation.

The circulating floating bed reactor: effect of particle size distribution of the carrier on ammonia conversion

2000 ◽  
Vol 41 (4-5) ◽  
pp. 393-400 ◽  
Author(s):  
J.M. Garrido-Fernandez ◽  
R. Méndez ◽  
J.M. Lema ◽  
V. Lazarova
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
G Protein ◽  
Biomass Concentration ◽  
Biomass Accumulation ◽  
Ammonia Removal ◽  
Operating Conditions ◽  
Nitrification Rate ◽  
Ammonia Conversion ◽  
Biomass Activity

Three Circulating Floating Bed Reactors (CFBR) R1, R2 and R3 with 20% v/v of a plastic carrier with different size distribution were operated to study the effect of the particles size of the carrier on biomass accumulation and nitrification performance. Operating conditions were similar in the three systems: ammonia concentrations around 50 mg-N–NH4+/ L, ammonia loading rates up to 1.2 kg N–NH4+/m3·d and temperatures between 14 and 27°C. Accumulation of nitrite was observed until day 65th. This w as result both of the inhibition of nitrite oxidation by free ammonia until day 20th and the insignificant accumulation of a biomass with low nitrite oxidising capacity between days 20 and 65th. Ammonia conversion rate and removal efficiency were higher in the reactor with lower particle size, R3 (nitrification rate of 1.1 kg N–NH4+/m3·d and ammonia removal of 97% at 16°C), than in R2 or R1 (nitrification rate of 1.0 kg N–NH4+/m3·d and ammonia removal of 90% at 16°C). The better efficiency in R3 was obtained as a result of the higher specific surface of the biofilm developed. Biomass activity was similar in the three reactors (2.2 and 1.12 g N/g protein · d at 30 and 15°C, respectively). Both the biomass evolution with time and biomass retention in the systems was practically not influenced by the size of particle. Biomass concentration of 1.2 g protein/L was retained in the carrier and up to 20% of the newly produced biomass was retained in the CFBRs.

scholarly journals A Numerical Study of the Effect of Particle Size on Particle Deposition on Turbine Vanes and Blades

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110178
Author(s):  
Zhengang Liu ◽  
Weinan Diao ◽  
Zhenxia Liu ◽  
Fei Zhang
Keyword(s):  
Particle Size ◽  
Particle Deposition ◽  
Numerical Study ◽  
Stokes Number ◽  
Capture Efficiency ◽  
Particle Capture ◽  
Factors Affecting ◽  
Pressure Surface ◽  
Deposition Area ◽  
Turbine Vanes

Particle deposition could decrease the aerodynamic performance and cooling efficiency of turbine vanes and blades. The particle motion in the flow and its temperature are two important factors affecting its deposition. The size of the particle influences both its motion and temperature. In this study, the motion of particles with the sizes from 1 to 20 μm in the first stage of a turbine are firstly numerically simulated with the steady method, then the particle deposition on the vanes and blades are numerically simulated with the unsteady method based on the critical viscosity model. It is discovered that the particle deposition on vanes mainly formed near the leading and trailing edge on the pressure surface, and the deposition area expands slowly to the whole pressure surface with the particle size increasing. For the particle deposition on blades, the deposition area moves from the entire pressure surface toward the tip with the particle size increasing due to the effect of rotation. For vanes, the particle capture efficiency increases with the particle size increasing since Stokes number and temperature of the particle both increase with its size. For blades, the particle capture efficiency increases firstly and then decreases with the particle size increasing.

Impact of climatic conditions on the parameters of failure flow of military vehicles

2021 ◽  
pp. 095440702110202
Author(s):  
Nikolaj Dobrzinskij ◽  
Algimantas Fedaravicius ◽  
Kestutis Pilkauskas ◽  
Egidijus Slizys
Keyword(s):  
Climatic Factors ◽  
Armed Forces ◽  
Climatic Conditions ◽  
Operating Conditions ◽  
Technical Equipment ◽  
Factors Affecting ◽  
Military Vehicles ◽  
Equipment Reliability ◽  
Number Of Factors ◽  
The Impact

Relevance of the article is based on participation of armed forces in various operations and exercises, where reliability of machinery is one of the most important factors. Transportation of soldiers as well as completion of variety of tasks is ensured by properly functioning technical equipment. Reliability of military vehicles – armoured SISU E13TP Finnish built and HMMWV M1025 USA built were selected as the object of the article. Impact of climatic conditions on reliability of the vehicles exploited in southwestern part of the Atlantic continental forest area is researched by a case study of the vehicles exploitation under conditions of the climate of Lithuania. Reliability of military vehicles depends on a number of factors such as properties of the vehicles and external conditions of their operation. Their systems and mechanisms are influenced by a number of factors that cause different failures. Climatic conditions represent one of the factors of operating load which is directly dependent on the climate zone. Therefore, assessment of the reliability is started with the analysis of climatic factors affecting operating conditions of the vehicles. Relationship between the impact of climatic factors and failure flow of the vehicles is presented and discussed.

Investigation of the different particle size dust releases from rigid filter candles during pulse-jet cleaning

2021 ◽  
pp. 095440622110179
Author(s):  
Xin Luan ◽  
Zhongli Ji ◽  
Longfei Liu ◽  
Ruifeng Wang
Keyword(s):  
Particle Size ◽  
Critical Role ◽  
Operating Conditions ◽  
Solid Particles ◽  
Dust Particles ◽  
Cleaning Efficiency ◽  
Term Operation ◽  
Cleaning Performance ◽  
Experimental Apparatus ◽  
Pulse Jet

Rigid filters made of ceramic or metal are widely used to remove solid particles from hot gases at temperature above 260 °C in the petrochemical and coal industries. Pulse-jet cleaning of fine dust from rigid filter candles plays a critical role in the long-term operation of these filters. In this study, an experimental apparatus was fabricated to investigate the behavior of a 2050 mm filter candle, which included monitoring the variation of pressure dynamic characteristics over time and observing the release of dust layers that allowed an analysis of the cleaning performance of ISO 12103-1 test dusts with different particle size distributions. These results showed the release behavior of these dusts could be divided into five stages: radial expansion, axial crack, flaky release, irregular disruption and secondary deposition. The cleaning performance of smaller sized dust particles was less efficient as compared with larger sized dust particles under the same operating conditions primarily because large, flaky-shaped dust aggregates formed during the first three stages were easily broken into smaller, dispersed fragments during irregular disruption that forced more particles back to the filter surface during secondary deposition. Also, a “low-pressure and long-pulse width” cleaning method improved the cleaning efficiency of the A1 ultrafine test dust from 81.4% to 95.9%.

scholarly journals Physicochemical factors affecting the wettability of copper mine blasting dust

2021 ◽  
Author(s):  
Longzhe Jin ◽  
Jianguo Liu ◽  
Jingzhong Guo ◽  
Jiaying Wang ◽  
Tianyang Wang
Keyword(s):  
Particle Size ◽  
Physicochemical Properties ◽  
Pore Structure ◽  
Total Pore Volume ◽  
Open Pit ◽  
X Rays ◽  
Factors Affecting ◽  
Copper Mine ◽  
Mineral Components ◽  
Hydrophobic Component

AbstractTo investigate the factors affecting the wettability of copper mine blasting dust, the primary blasting dust was collected from an open-pit copper mine and separated into hydrophilic blasting dust (HLBD) and hydrophobic blasting dust (HBBD) using water flotation method. The physicochemical properties of HLBD and HBBD were measured and compared with each other. The properties included particle size distributions (PSDs), micromorphologies, pore structures, mineral components and surface organic carbon functional groups. The results show that particle size and pore structure of the blasting dust are the main factors affecting its wettability. Specifically, particle size of HBBD is smaller than that of HLBD, and their respiratory dust (less than 10 µm) accounts for 61.74 vol% and 53.00 vol%, respectively. The pore structure of HBBD is more developed, and the total pore volume of HBBD is 1.66 times larger than that of HLBD. The identical mineral compositions were detected in HLBD and HBBD by X-rays diffraction (XRD); however, the surface organic hydrophobic component of HBBD is slightly larger than that of HLBD, this may be the reason for the poor wettability of HBBD. This study is significant to understand the effects of physicochemical properties of copper mine blasting dust on its wettability.

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