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Kraft recovery boiler operation with splash plate and/or beer can nozzles — a case study, TAPPI Journal Octobr 2021

ABSTRACT: In this work, we study a boiler experiencing upper furnace plugging and availability issues. To improve the situation and increase boiler availability, the liquor spray system was tuned/modified by testing different combinations of splash plate and beer can nozzles. While beer cans are typically used in smaller furnaces, in this work, we considered a furnace with a large floor area for the study. The tested cases included: 1) all splash plate nozzles (original operation), 2) all beer can nozzles, and 3) splash plate nozzles on front and back wall and beer cans nozzles on side walls. We found that operating according to Case 3 resulted in improved overall boiler operation as compared to the original condition of using splash plates only. Additionally, we carried out computational fluid dynamics (CFD) modeling of the three liquor spray cases to better understand the furnace behavior in detail for the tested cases. Model predictions show details of furnace combus-tion characteristics such as temperature, turbulence, gas flow pattern, carryover, and char bed behavior. Simulation using only the beer can nozzles resulted in a clear reduction of carryover. However, at the same time, the predicted lower furnace temperatures close to the char bed were in some locations very low, indicating unstable bed burning. Compared to the first two cases, the model predictions using a mixed setup of splash plate and beer can nozzles showed lower carryover, but without the excessive lowering of gas temperatures close to the char bed.

Corrosion damage and in-service inspection of retractable sootblower lances in recovery boilers, TAPPI Journal October 2021

ABSTRACT: Several reports of accidents involving serious mechanical failures of sootblower lances in chemical recovery boilers are known in the pulp and paper industry. These accidents mainly consisted of detachment and ejection of the lance tip, or even of the entire lance, to the inside of the furnace, towards the opposite wall. At least one of these cases known to the author resulted in a smelt-water explosion in the boiler.In other events, appreciable damage or near-miss conditions have already been experienced. The risk of catastrophic consequences of the eventual detachment of the lance tip or the complete lance of a recovery boiler soot-blower has caught the attention of manufacturers, who have adjusted their quality procedures, but this risk also needs to be carefully considered by the technical staff at pulp mills and in industry committees.This paper briefly describes the failure mechanisms that prevailed in past accidents, while recommending inspection and quality control policies to be applied in order to prevent further occurrences of these dangerous and costly component failures. Digital radiography, in conjunction with other well known inspection techniques, appears to be an effective means to ensure the integrity of sootblower lances in chemical recovery boilers used in the pulp and paper industry.

The Effect of Contact Time Between CPAM and Colloidal Silica on the Flocculation Behaviour in the Approach Flow, 2021 TAPPICon Live (21TAPL)

The Effect of Contact Time Between CPAM and Colloidal Silica on the Flocculation Behaviour in the Approach Flow, 2021 TAPPICon Live (21TAPL)

Furnishing autohydrolyzed poplar weakly alkaline P-RC APMP to make lightweight coated base paper, TAPPI Journal February 2022

ABSTRACT: This work investigated the effects of autohydrolysis pretreatment severity on poplar (Populus tomentosa Carr.) woodchips used to make a type of high-yield pulp (HYP) known as preconditioning followed by refiner chemical treatment, alkaline peroxide mechanical pulp (P-RC APMP). It also investigated the ratios for partially replacing sodium hydroxide (NaOH) with magnesium oxide (MgO) in the high-consistency (HC) retention stage of the P-RC APMP process on the obtained HYP’s properties. The results show that the pretreatment severity of autohydrolysis at combined hydrolysis factor (CHF) = 10.77 and the 50 wt% ratio for partially substituting NaOH with MgO were the optimum conditions for making light-weight coated (LWC) base paper. Compared to the conventional P-RC APMP, the optimized P-RC APMP had similar bulk and higher tensile, burst, and tear indices, as well as opacity, but a slightly lower ISO brightness. When the optimized P-RC APMP and commercial softwood bleached sulfate pulp (SBKP) were blended to make LWC base paper, the most favorable pulp furnish was comprised of 50% optimized P-RC APMP and 50% commercial SBKP. The obtained LWC base paper handsheet had better bulk, and its other properties could also meet the require-ments of LWC base paper.

Tim Nicholls is the New Executive VP and President of DS Smith

Stora Enso and ECOR Global Partner to Create Formaldehyde-Free Board

Precision steam path dimensional measurement, the key to developing competitive steam path rerates, and advanced technology component upgrades, 2012 TAPPI PEERS Conference

Precision steam path dimensional measurement, the key to developing competitive steam path rerates, and advanced technology component upgrades, 2012 TAPPI PEERS Conference

Liquid plasma polymerization process for improved deinkability of pigmented inkjet digital printed paper, 2012 TAPPI PEERS Conference

Liquid plasma polymerization process for improved deinkability of pigmented inkjet digital printed paper, 2012 TAPPI PEERS Conference

A Novel Recovery and Recycle Process for Catalytic Molybdate in Acidic Peroxide Delignification, 2011 International Pulp Bleaching Conference

A Novel Recovery and Recycle Process for Catalytic Molybdate in Acidic Peroxide Delignification, 2011 International Pulp Bleaching Conference

STEADY-STATE ELEMENTAL CHLORINE-FREE (ECF) BLEACH SEQUENCE MODELING FOR OPTIMIZATION: A REVIEW OF TECHNIQUES AND NEW APPLICATIONS, 2011 International Pulp Bleaching Conference

STeady-State ELemental Chlorine-free (ECF) Bleach Sequence Modeling for Optimization: A Review of Techniques and New Applications, 2011 International Pulp Bleaching Conference