| 1. |
|
|
| 2. |
- Berglin, Niklas, et al.
(författare)
-
Experiences from feeding and co-firing of lignin powder in a lime kiln
- 2010
-
Ingår i: International Chemical Recovery Conference. ; , s. 175-187
-
Konferensbidrag (refereegranskat)abstract
- A significant part of the fossil fuel oil consumption at a pulp mill today is related to combustion in the lime kiln. Therefore, replacing fuel oil with lignin in this application has been one of the most important issues in the FRAM2 (Future Resource-Adapted Mill) research program coordinated by Innventia (formerly STFl-Packforsk) and funded by Sodra and other partners. A full-scale trial to fire lignin powder in a lime kiln was carried out at the Sodra Cell Monsteras mill, as part of the research program. In total 37 tonnes of lignin was co-fired with fuel oil. For part of the trial the kiln was operated on 100 % lignin. The experiences from the trial imply that it is possible to achieve stable and continuous operation of a lime kiln when lignin is used as the main fuel. The temperature levels in the kiln are of the same order of magnitude as when firing fuel oil or wood powder. Sulfur capture by the lime is very efficient, but there is a threshold above which S02 emissions increase rapidly. In the trial this step change occurred when going from 90 % to 100 % lignin firing. Based on the trial results, it is possible to produce lime with consistent quality when firing lignin, and the temperature reached in the burner zone is sufficient for proper sintering of the lime nodules. White liquor can be produced from the lime with the same causticizing efficiency and at the same rate as during normal operation. The mill operators also commented that it was easier to control the performance of the kiln when co-firing lignin and oil compared to the normal operation with co-firing of bark and oil.
|
|
| 3. |
- Berglin, N., et al.
(författare)
-
Pilot-scale combustion studies with kraft lignin in a powder burner and a CFB boiler
- 2010
-
Ingår i: Tappi Journal. - 0734-1415. ; 9:6, s. 24-30
-
Tidskriftsartikel (refereegranskat)abstract
- Processes have been developed to produce a solid biofuel with high energy density and low ash content from kraft lignin precipitated from black liquor. Pilot-scale tests of the lignin biofuel were carried out with a 150 kW powder burner and a 12 MW circulating fluidized bed (CFB) boiler. Lignin powder could be fired in a powder burner with good combustion performance after some trimming of the air flows to reduce swirl. Lignin dried to 10% moisture content was easy to feed smoothly and had less bridging tendencies in the feeding system than did wood/bark powder. In the CFB boiler, lignin was easily handled and cofired together with bark. Although the filter cake was broken into smaller pieces and fines, the combustion was not disturbed. When cofiring lignin with bark, the sulfur emission increased compared with bark firing only, but most of the sulfur was captured by calcium in the bark ash. Conventional sulfur capture also occurred with addition of limestone to the bed. The sulfur content in the lignin had a significantly positive effect on reducing the alkali chloride content in the deposits, thus reducing the high temperature corrosion risk.
|
|
| 4. |
- da Silva, Paulo S P, et al.
(författare)
-
Release of carbon and nitrogen during pylolysis of reduced lignin black liquors : experimental results
- 2017
-
Ingår i: International chemical recovery conference, May 24-26, 2017, Halifax, Canada.
-
Konferensbidrag (refereegranskat)abstract
- Removing lignin from black liquor is of increasing industrial interest. It has the potential to create a new product stream for pulp mills as well as being a method for reducing the load of over-loaded recovery boilers. Currently, there is very little information on the combustion properties of reduced lignin black liquors. Of particular importance is the split of carbon and nitrogen. The carbon split is especially important because it plays an important role in how much carbon reaches the char bed. This in turn affects the lower furnace temperature, which plays an important role in reduction efficiency; sulfur and alkali release; and NO and cyanate formation. The nitrogen split is of interest because a part of the black liquor nitrogen precipitates with the lignin, potentially changing the behavior of black liquor N. The purpose of this work is to investigate the effect of lignin removal on carbon and nitrogen distribution between volatiles and char during pyrolysis. In this work, black liquors (one SW and one eucalyptus) with different levels of lignin removal were pyrolysed in a single particle furnace for 2 seconds at temperatures from 900°C to 1100°. Additional softwood and hardwood liquors were also pyrolyzed in order to study liquor to liquor variability. The carbon and nitrogen splits were obtained by analyzing the chars from the pyrolysis experiments using a CHNS elemental analyzer. Results show a similar carbon split for liquors with up to 25% lignin removal. The nitrogen split was also found to be fairly consistent with approximately 45% of the nitrogen staying with the char. This information has partly been used in another study in the CFD modeling of the combustion of black liquor with different levels of lignin removal.
|
|
| 5. |
- Gellerstedt, Göran L. F., et al.
(författare)
-
Removal of non-process elements from hardwood chips prior to kraft cooking
- 2005
-
Ingår i: The 13th International Symposium on Wood, Fibre and Pulping Chemistry, Auckland, New Zealand, May 2005. - 1443-5454. ; 2, s. 147-154
-
Konferensbidrag (refereegranskat)abstract
- The major part of the intake of non-process elements (NPE's) to the pulp mill is via the wood chips. Some of the problems associated with NPE's are e.g. precipitation of sparingly soluble calcium salts in the fibre line and in the recovery department. In order to investigate the possibilities of reducing the intake of NPE's via hardwood chips to the pulp mill, laboratory studies on the acidic leaching of birch and eucalyptus chips were carried out. The results showed that potassium, magnesium and manganese were removed from both wood species at similar rates. The removal of calcium was however significantly slower from eucalyptus than from birch. Removal of NPE's from birch wood chips prior to cooking resulted in a higher rate of delignification, a higher unbleached brightness and a higher viscosity. In the case of eucalyptus, acidic leaching had no effect on the rate of delignification. The positive effect of acidic leaching of birch chips was found to be due to a lower content of calcium in the cooking stage.
|
|
| 6. |
|
|
| 7. |
- Jönsson, Ann-Sofi, et al.
(författare)
-
Treatment of paper coating colour effluents by membrane filtration
- 1996
-
Ingår i: Desalination. - : Elsevier BV. - 1873-4464 .- 0011-9164. ; 105:3, s. 263-276
-
Tidskriftsartikel (refereegranskat)abstract
- Dilute coating colour effluents are created during the coating of paper and board. After treating the colour effluents with ultrafiltration, the retentate can be reused as coating colour and the permeate can replace fresh water. At the same time, the load on the external treatment plant is reduced. In this investigation, pilot-plant experiments were performed at a paper mill. A high and steady flux, 120 l/m(2) h, was achieved at a colour concentration of 10-15%. The flux at 40% was lower but steady, 50 l/m(2) h. The membrane performance when treating five coating colours with varying composition was studied in laboratory experiments. The composition of the colour had a significant influence on the membrane performance. A colour containing starch exhibited the lowest flux and the lowest COD retention of the colours included in the study, while a colour in which the clay had been replaced by CaCO3 exhibited the highest final concentration of 60%.
|
|
| 8. |
- Mikeš, P., et al.
(författare)
-
The Mass Production of Lignin Fibres by Means of Needleless Electrospinning
- 2021
-
Ingår i: Journal of Polymers and the Environment. - : Springer. - 1566-2543 .- 1572-8919. ; 29:7, s. 2164-2173
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract: Lignin, a cheap renewable natural polymer, can be used as a precursor for the production of carbon fibres, its conversion into which is significantly faster than that of polyacrylonitrile. Lignin can be fractionated in various solvents via dissolution to decrease its polydispersity. Fractions with a higher molecular weight distribution can then be used in solvent-based spinning technologies such as electrospinning. We selected several solvent systems according to the Hansen solubility theory and subsequently tested them for solubility and electro-spinability. The selected solvent systems were then successfully tested for use in the needleless electrospinning process due to their potential for mass production. The solutions used in the electrospinning process needed high concentrations of lignin, which led to a high degree of viscosity. Therefore, we measured the relaxation times and viskosity for selected solutions, a factor that plays a pivotal role in terms of the production of smooth fibres. Finally, these solutions were tested for electrospinning using alternating current. This technology brings a new possibility in mass production of lignin fibres due to its high productivity and ease of use. Such materials can be used in a number of applications such as batteries, supercapacitors or for the production of composite materials. They provide a cheap and renewable natural polymer source which can easily be transformed into a carbon nanofibrous layer. Graphic Abstract: [Figure not available: see fulltext.].
|
|
| 9. |
- Schlee, Philipp, et al.
(författare)
-
Hardwood : versus softwood Kraft lignin-precursor-product relationships in the manufacture of porous carbon nanofibers for supercapacitors
- 2020
-
Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 8:44, s. 23543-23554
-
Tidskriftsartikel (refereegranskat)abstract
- The process of stabilization is essential in the production of carbon fibers from lignins. During stabilization, the initially thermoplastic lignin polymer is converted to a thermoset polymer allowing for high-temperature treatment without a change in shape. In this work, hardwood (HKL) and softwood (SKL) Kraft lignins were stabilized in air at temperatures between 190 and 340 °C before carbonization at 800 °C in a nitrogen atmosphere. Due to the differences in side-chain linkages, functional groups and molar mass, the lignins exhibit different structural changes upon stabilization and hence develop different porosities upon carbonization. Both lignins undergo major crosslinking reactions in the side chains at low temperatures and degradation reactions at high temperatures during stabilization. Crosslinking gives rise to narrow pore size distributions with mainly (sub-) nanometer pores, whereas degradation reactions lead to a more open pore structure with additional mesoporosity (>2 nm). When both types of reactions take place simultaneously, highly accessible (sub-) nanoporosity can be effectively created, which boosts the performance of supercapacitors operating in 6 M KOH(aq). This effect terminates when the crosslinking reactions cease and mainly degradation reactions take place, which occurs in HKL at 340 °C. SKL shows both a lower degree of crosslinking and degradation and hence develops less specific surface area. The optimum performance in an aqueous alkaline supercapacitor is achieved with HKL stabilized at 310 °C. It shows a specific gravimetric capacitance of 164 F g-1 at 0.1 A g-1 and 119 F g-1 at 250 A g-1 with a capacitance retention of more than 90% after 10 000 cycles.
|
|
| 10. |
- Strömberg, Jan, 1962, et al.
(författare)
-
Energy-Efficient closed-cycled Bleaching
- 1997
-
Ingår i: Presented at the 1997 TAPPI Minimum Effluent Mills Symposium October 23- 24, 1997 San Francisco, USA.. - 1103-2952.
-
Konferensbidrag (refereegranskat)
|
|
