Review of Some Data on Corrosion of Stainless Steel and Higher Alloys in Pulp Mill Equipment

CORROSION ◽  
1961 ◽  
Vol 17 (6) ◽  
pp. 9-13
Author(s):  
Harold C. Templeton
Keyword(s):  
Carbon Steel ◽  
Black Liquor ◽  
Pulp Mill ◽  
High Strength ◽  
Case Histories ◽  
Good Resistance ◽  
Green Liquor ◽  
Corrosion Rates ◽  
Alkaline Pulping ◽  
Mill Equipment

Abstract Allowable corrosion rates for equipment with low corrosion tolerance are discussed. Corrosion case histories in the various pulping processes are presented. Sulfite pulping solutions are most frequently-handled in 316 material. Stainless 316 is used because of good resistance to local attack under scale or deposits. In alkaline pulping, soda process digesters are usually made of carbon steel with heater tubing of either carbon steel or Type 316 alloy. Kraft digesters are commonly carbon steel, though many units are partially to wholly lined with alloy materials. Type 316 most frequently. Stainless 316 is used for heater piping, strong black liquor piping and green liquor piping. Carbon steel is most frequently used for weak black liquor. Corrosion in groundwood pulping varies greatly depending on wood being ground, water supply and treating chemicals added. Stainless 304 and 316 alloys are used frequently, both to resist corrosion and reduce contamination. Chlorine and hypochlorite bleaching usually pose severe corrosion problems. Hastelloy C alloy is most commonly used for high strength solutions. In more dilute solutions the molybdenum-bearing. stainless steels are satisfactory. Chlorine dioxide is even more corrosive to metals than hypochlorite, and some operators have replaced Hastelloy C with titanium. 8.5.3

Fate of biosludge nitrogen in black liquor evaporation and combustion

TAPPI Journal ◽  
2012 ◽  
Vol 11 (9) ◽  
pp. 53-59 ◽  
Author(s):  
NIKLAS VÄHÄ-SAVO ◽  
NIKOLAI DEMARTINI, ◽  
MIKKO HUPA
Keyword(s):  
Black Liquor ◽  
Pulp Mill ◽  
Chemical Recovery ◽  
Process Data ◽  
Green Liquor ◽  
No Formation ◽  
Kraft Recovery Boilers ◽  
Recovery Boilers ◽  
Recovery Boiler ◽  
Clear Increase

At many mills, biosludge, which has a high nitrogen content, is added to black liquor and burned in kraft recovery boilers. The aim of this work was to determine the fate of biosludge nitrogen in the high solids black liquor concentrators and in the recovery boiler. Specifically, does biosludge addition result in higher nitric oxide (NO) and cyanate formation during black liquor combustion? To obtain this information, samples were collected from the chemical recovery cycle of a Finnish kraft pulp mill along with relevant process data. Laboratory combustion experiments clearly showed an increase in NO formation for the mill black liquor with biosludge, but no clear increase in nitrogen oxide emissions was detected in the recovery boiler after biosludge addition. Analysis of the green liquor samples from the dissolving tank showed a significant increase in nitrogen exiting the recovery boiler as cyanate. This finding was supported by laboratory tests studying cyanate formation. The increased cyanate results in increased ammonia formation in the recausticizing cycle, which can lead to higher NO emissions, as seen in the noncondensible gas incinerator at the mill.

Role of Wood Extractives in Black Liquor Corrosiveness

CORROSION ◽  
2006 ◽  
Vol 62 (10) ◽  
pp. 911-917 ◽  
Author(s):  
P. E. Hazlewood ◽  
P. M. Singh ◽  
J. S. Hsieh
Keyword(s):  
Carbon Steel ◽  
Wood Species ◽  
Paper Industry ◽  
Black Liquor ◽  
Wood Chip ◽  
Pulp Mill ◽  
Kraft Pulping ◽  
Extractive Content ◽  
Operational Parameters ◽  
Black Liquors

Abstract In the pulp and paper industry, variability in the process and wood source may result in highly corrosive waste liquors, called black liquors, from the Kraft pulping process. Prior research has demonstrated corrosion rates of carbon steel in pulp mill equipment ranging from <0.03 mm/y to >2.54 mm/y, depending on the wood species pulped. In this study wood species-dependent corrosion is confirmed and age-dependent corrosion is investigated as a function of organic extractive content. The composition of the organic portion of black liquor depends largely on the wood species used. Organic components come from extractives in the wood chips or are generated from the degradation of lignin and other wood constituents during the pulping process. Depending upon the wood species used, some black liquor constituents have been identified to increase the corrosiveness of black liquors whereas others may act as corrosion inhibitors. Our research demonstrates the importance of operational parameters for wood species and wood chip usage and delivery to downstream process corrosion. Further, results show the importance of water-extracted organics in wood, such as long chain fatty acids, using a novel methodology for the separation of extractives and lignin breakdown products in the testing of black liquor corrosiveness with carbon steel A516-Grade 70 (UNS K02700).

Qualification of High Strength Carbon Steel Wires for Use in Specific Annulus Environment of Flexible Pipes Containing CO2 and H2S

2006 ◽  
Author(s):  
Carol Taravel-Condat ◽  
Nicolas Desamais
Keyword(s):  
Carbon Steel ◽  
Corrosion Fatigue ◽  
High Strength ◽  
Full Scale ◽  
Small Scale ◽  
Annular Space ◽  
Flexible Pipe ◽  
Corrosion Rates ◽  
Steel Wires ◽  
Flexible Pipes

Flexible pipes have been used for many years in offshore applications for the transportation of crude oil, gas and water. Such structures are subjected to mechanical loads due to tension, high internal pressure and dynamic motions which are sustained by the use of high strength carbon steel wires. The steel wires are located in the annular space that may contain water and acid gas (CO2, H2S) which can be detrimental for steels. For that reason, risks of Sulfide Stress Corrosion Cracking (SSCC) and Hydrogen Induced Cracking (HIC) shall be considered. Moreover, for dynamic conditions, presence of corrosive environment in the annulus could significantly reduce the fatigue performance of flexible pipe compared to air environment. The annulus composition is calculated using a permeability model that has been validated with medium scale tests, full scale tests and field cases [1]. In parallel, corrosion and corrosion fatigue studies have shown that the annulus of a flexible pipe is a very confined space with over-saturation in iron and no renewal of oxygen. This results in a higher pH, much lower corrosion rates and less HIC and SSCC than one would expect based on normal environments. This paper presents, in a first part, the different results obtained during small scale corrosion and corrosion fatigue tests demonstrating the beneficial specificity of the annular space. In a second part, the paper presents the results of pH measurements and corrosion rates obtained during a full scale dynamic corrosion fatigue test in CO2/H2S environment validating the previous results. This test was conducted on a 6” pipe between 1999 and 2003. In a third part, the paper describes how the annulus specificities should be used today to determine the suitability of carbon steel wires for use in flexible flowlines and risers considering SSCC, HIC, corrosion and corrosion fatigue.

Biorefinery implementation for recovery debottlenecking at existing pulp mills- Part II: Techno-economic evaluation

TAPPI Journal ◽  
2012 ◽  
Vol 11 (8) ◽  
pp. 17-24 ◽  
Author(s):  
HAKIM GHEZZAZ ◽  
LUC PELLETIER ◽  
PAUL R. STUART
Keyword(s):  
Cost Estimation ◽  
Process Model ◽  
Black Liquor ◽  
Pulp Mill ◽  
Value Added ◽  
Economic Assessment ◽  
Extraction Process ◽  
Estimation Methods ◽  
Precipitation Process

The evaluation and process risk assessment of (a) lignin precipitation from black liquor, and (b) the near-neutral hemicellulose pre-extraction for recovery boiler debottlenecking in an existing pulp mill is presented in Part I of this paper, which was published in the July 2012 issue of TAPPI Journal. In Part II, the economic assessment of the two biorefinery process options is presented and interpreted. A mill process model was developed using WinGEMS software and used for calculating the mass and energy balances. Investment costs, operating costs, and profitability of the two biorefinery options have been calculated using standard cost estimation methods. The results show that the two biorefinery options are profitable for the case study mill and effective at process debottlenecking. The after-tax internal rate of return (IRR) of the lignin precipitation process option was estimated to be 95%, while that of the hemicellulose pre-extraction process option was 28%. Sensitivity analysis showed that the after tax-IRR of the lignin precipitation process remains higher than that of the hemicellulose pre-extraction process option, for all changes in the selected sensitivity parameters. If we consider the after-tax IRR, as well as capital cost, as selection criteria, the results show that for the case study mill, the lignin precipitation process is more promising than the near-neutral hemicellulose pre-extraction process. However, the comparison between the two biorefinery options should include long-term evaluation criteria. The potential of high value-added products that could be produced from lignin in the case of the lignin precipitation process, or from ethanol and acetic acid in the case of the hemicellulose pre-extraction process, should also be considered in the selection of the most promising process option.

Managing total reduced sulfur emissions at a Canadian kraft pulp mill

TAPPI Journal ◽  
2016 ◽  
Vol 15 (4) ◽  
pp. 265-272 ◽  
Author(s):  
ROHAN BANDEKAR ◽  
JIM FREDERICK ◽  
JAROSLAV STAVIK
Keyword(s):  
Direct Contact ◽  
Black Liquor ◽  
Pulp Mill ◽  
Packed Bed ◽  
Average Value ◽  
Emission Limit ◽  
Total Reduced Sulfur ◽  
Reduced Sulfur ◽  
Air Ingress ◽  
Solids Content

This study addresses the challenges a dissolving-grade pulp mill in Canada faced in 2014 in meeting its total reduced sulfur (TRS) gas emission limit. These emissions from the recovery boiler exit are controlled by passing the boiler exit gas through a TRS scrubber system. The mill employs a cyclonic direct contact evaporator to concentrate black liquor to firing solids content. The off-gases from the direct contact evaporator flow to the effluent gas control system that consists of a venturi scrubber, a packed bed scrubber, and a heat recovery unit. Emissions of TRS greater than the regulated limit of 15 ppm were observed for a 4-month period in 2014. The level of emissions measured during this period was significantly higher than about 12 ppm, the expected average value based on historic experience. The problem persisted from mid-June 2014 until the annual mill shutdown in October 2014. The main TRS components detected and the performance of the Teller scrubber in capturing them are examined. Other potential causes for these emissions are identified, including mechanical problems such as broken packing in the TRS packed bed scrubber, broken baffle plates in the scrubber, and cyclone evaporator leaks causing air ingress. Repairs were carried out during the mill shutdown, which eliminated the TRS emissions problem.

Commissioning brownstock washing controls for an evaporator limited mill

TAPPI Journal ◽  
2016 ◽  
Vol 15 (7) ◽  
pp. 459-464
Author(s):  
RICARDO SANTOS ◽  
PETER HART
Keyword(s):  
Control System ◽  
Negative Impact ◽  
Black Liquor ◽  
Pulp Mill ◽  
Control Program ◽  
Separation Point ◽  
Water Control ◽  
Oxygen Delignification ◽  
Percentage Points

An automated shower water control system has been implemented to reduce the volume and variability of weak black liquor being sent from the pulp mill to the evaporators. The washing controls attempt to balance the need for consistent and low soda carryover to the bleach plant with consistently high weak black liquor solids being sent to the evaporators. The washer controls were implemented on two bleachable grade hardwood lines (one with oxygen delignification, one without oxygen delignification) and one pine line. Implementation of the control program resulted in an increase in black liquor solids of 0.6 percentage points for the hardwood lines. Significant foam reduction was realized on the pine line since the pine black liquor solids were able to be consistently maintained just below the soap separation point. Low black liquor solids excursions to the evaporators were eliminated. Bleach plant carryover was stabilized and no negative impact on chemical consumption was noticed when controlling weak black liquor solids to recovery.

COPPER ALLOY No. 954

Alloy Digest ◽  
1975 ◽  
Vol 24 (2) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Copper Alloy ◽  
Iron Alloy ◽  
High Strength ◽  
Heat Treating ◽  
Good Resistance ◽  
Excellent Corrosion Resistance ◽  
Aluminum Iron ◽  
Copper Aluminum

Abstract Copper Alloy No. 954 is a copper-aluminum-iron alloy characterized by high strength and hardness, good resistance to fatigue and wear, and excellent corrosion resistance. It is suited for service up to 750 F. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Cu-292. Producer or source: Copper alloy foundries.

UNS A03560

Alloy Digest ◽  
1986 ◽  
Vol 35 (12) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
High Strength ◽  
Heat Treating ◽  
Casting Alloy ◽  
Aluminum Casting ◽  
Good Resistance ◽  
Aluminum Casting Alloy ◽  
Temperature Performance ◽  
Heat Treated

Abstract UNS No. A03560 is a heat-treatable aluminum casting alloy. Normally it is used only when heat-treated (aged) strengths are required. It is recommended for high-strength, pressure-tight castings, intricate shapes and where good resistance to corrosion is needed. Its many applications include crank cases, gear cases, oil pans, airframe fittings and instrument housings. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance and corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Al-274. Producer or source: Various aluminum companies.

UNS N09706

Alloy Digest ◽  
1989 ◽  
Vol 38 (2) ◽  
Keyword(s):  
High Strength ◽  
Heat Treating ◽  
Chromium Alloy ◽  
Good Resistance ◽  
Nickel Iron ◽  
Temperature Performance ◽  
Resistance To Oxidation ◽  
Oxidation And Corrosion ◽  
Iron Chromium Alloy ◽  
Iron Chromium

Abstract UNS N09706 is a precipitation-hardenable, nickel-iron-chromium alloy with high strength at temperatures to 1200 F and with good resistance to oxidation and corrosion over a broad range of temperatures and environments. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep and fatigue. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-368. Producer or source: Nickel and nickel alloy producers.

AMPCO 483

Alloy Digest ◽  
1978 ◽  
Vol 27 (4) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Tensile Properties ◽  
Base Alloy ◽  
High Hardness ◽  
High Strength ◽  
Heat Treating ◽  
Good Resistance ◽  
Copper Base ◽  
Copper Base Alloy

Abstract AMPCO 483 is a copper-base alloy that can be used in the cast or wrought form. It provides high strength, high hardness, excellent resistance to corrosion and good resistance to fatigue and wear. It is well suited for service at temperatures up to 750 F and for applications such as pickling equipment, nuts and marine hardware. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as casting, forming, heat treating, machining, and joining. Filing Code: Cu-352. Producer or source: Ampco Metal Inc..

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