scholarly journals Addressing production bottlenecks and brownstock washer optimization via a membrane concentration system

TAPPI Journal ◽  
2021 ◽  
Vol 20 (7) ◽  
pp. 467-478
Author(s):  
DIEGO F. RIVERA ◽  
MAX KLEIMAN-LYNCH ◽  
BRENT D. KELLER ◽  
STEPHEN F. FRAYNE
Keyword(s):  
Black Liquor ◽  
Operating Cost ◽  
Membrane System ◽  
Wash Water ◽  
Pulp Mills ◽  
Membrane Systems ◽  
Annual Operating Cost ◽  
Production Increase ◽  
The Impact ◽  
Pulp Production

Advancements in membrane systems indicate that they will soon be robust enough to concentrate weak black liquor. To date, the economic impact of membrane systems on brownstock washing in kraft mills has not been studied and is necessary to understand the viability of these emerging systems and their best utilization. This study investigated the savings that a membrane system can generate related to brownstock washing. We found that evaporation costs are the primary barrier for mills seeking to increase wash water usage. Without these additional evaporation costs, we showed that our hypothetical 1000 tons/day bleached and brown pulp mills can achieve annual savings of over $1.0 MM when operating at higher dilution factors and fixed pulp production rate. We then investigated the impact of increasing pulp production on mills limited by their equipment. In washer-limited mill examples, we calculated that membrane systems can reduce the annual operating cost for a 7% production increase by 91%. Similarly, in evaporator-limited mill examples, membrane systems can reduce the annual operating cost for a 7% production increase by 86%. These results indicated that membrane systems make a production increase significantly more feasible for these equipment-limited mills.

scholarly journals Life cycle design and efficiency strategy for sustainable membrane technology

2021 ◽  
Vol 880 (1) ◽  
pp. 012053
Author(s):  
K K Razman ◽  
A W Mohammad ◽  
M M Hanafiah
Keyword(s):  
Life Cycle ◽  
Impact Assessment ◽  
Assessment Tool ◽  
Membrane System ◽  
Membrane Systems ◽  
Unit System ◽  
Life Cycle Design ◽  
Sustainable System ◽  
Membrane Treatment ◽  
The Impact

Abstract Life Cycle Assessment (LCA) is an assessment tool to evaluate the potential environmental impact of a system or product throughout its life cycle. Results from LCA provides an insight on developing a more sustainable system while identifying its environmental hotspots. With recent advancements in membrane treatment systems especially for wastewater treatment (WWT), there is a rising interest in its sustainability aspect. Thus, it is crucial to review on previous published studies to highlight the challenges and achievements in implementing LCA for the membrane system. Hence, this paper presents a review of 33 recent papers published from year 2017-2020 conducting LCA on membrane systems for WWT. Bounded by the key frameworks of ISO standards, the analysis of papers showed variance in defining its functional unit, system boundaries, impact assessment categories and method to evaluate LCA, which makes it a challenge to do comparison. Some of the challenges discussed and highlighted in this paper include the inconsistencies in specifying the impact assessment and methodology used for some journals and the lack of LCA study in certain regional areas. A more uniform implementation of LCA should be considered to ensure the reliability and reproducibility of results to allow adoptions on novel or existing membrane systems.

Preliminary Economics of Black Liquor Gasifier/Gas Turbine Cogeneration at Pulp and Paper Mills

2000 ◽  
Vol 122 (2) ◽  
pp. 255-261 ◽  
Author(s):  
Eric D. Larson ◽  
Stefano Consonni ◽  
Thomas G. Kreutz
Keyword(s):  
Steam Turbine ◽  
Gas Turbines ◽  
Kraft Pulp ◽  
Performance Modeling ◽  
Black Liquor ◽  
Pulp Mills ◽  
Pulp And Paper Mills ◽  
Paper Mills ◽  
Combined Cycles ◽  
Pulp Production

Black liquor, the lignin-rich byproduct of kraft pulp production, is burned in boiler/steam turbine cogeneration systems at pulp mills today to provide heat and power for onsite use. Black liquor gasification technologies under development would enable this fuel to be used in gas turbines. This paper reports preliminary economics of 100-MWe scale integrated black-liquor gasifier/combined cycles using alternative commercially proposed gasifier designs. The economics are based on detailed full-load performance modeling and on capital, operating and maintenance costs developed in collaboration with engineers at Bechtel Corporation and Stone & Webster Engineering. Comparisons with conventional boiler/steam turbine systems are included. [S0742-4795(00)00402-6]

Economics Analysis of Sewage Source Heat Pump System

2009 ◽  
Author(s):  
Bing Wei ◽  
Bin Zhang ◽  
Lu Jiang ◽  
Wen Luo
Keyword(s):  
Heat Pump ◽  
Fossil Fuel ◽  
Operating Cost ◽  
Air Conditioner ◽  
Pump System ◽  
Heat Pump System ◽  
Advantages And Disadvantages ◽  
Annual Operating Cost ◽  
The Impact ◽  
Sewage Source

To sewage treatment plants, the sewage is plenteous and costless. If the sewage is utilized for air conditioning purpose, it will achieve more value. The temperature of sewage is basically constant in summer or winter. The treated sewage can be used for absorbing the condensing heat in summer and releasing heat to the building space in winter through the sewage heat exchanger. Especially the heating coefficient of the sewage source heat bump is higher in winter, which is an advantage to heating. In this paper the cooling and heating theory of the sewage source heat bump is briefly introduced, the advantages and disadvantages of sewage source heat bump system is explained. With an example in Beijing, China, compared with the boiler/ductless split air conditioner system, the initial investment and annual operating cost are calculated and the economics of the sewage source heat pump system is analyzed. At last the impact of fossil fuel rate and electric rate on the annual operating costs is analyzed. The calculating results showed that under the present rates of fossil fuel and electricity in China, the initial investment of the sewage source heat pump system is higher, the annual operating cost is lower than that of the boiler/ductless split air conditioner system. All these above will be good references for the actual applications of sewage source heat pump systems.

scholarly journals Preliminary Economics of Black Liquor Gasifier/Gas Turbine Cogeneration at Pulp and Paper Mills

1998 ◽  
Author(s):  
Eric D. Larson ◽  
Stefano Consonni ◽  
Thomas G. Kreutz
Keyword(s):  
Steam Turbine ◽  
Gas Turbines ◽  
Kraft Pulp ◽  
Performance Modeling ◽  
Black Liquor ◽  
Pulp Mills ◽  
Pulp And Paper Mills ◽  
Paper Mills ◽  
Combined Cycles ◽  
Pulp Production

Black liquor, the lignin-rich byproduct of kraft pulp production, is burned in boiler/steam turbine cogeneration systems at pulp mills today to provide heat and power for onsite use. Black liquor gasification technologies under development would enable this fuel to be used in gas turbines. This paper reports preliminary economics of 100-MWe scale integrated black-liquor gasifier/combined cycles using alternative commercially-proposed gasifier designs. The economics are based on detailed full-load performance modeling and on capital and operating and maintenance costs developed in collaboration with engineers at Bechtel Corporation and Stone and Webster Engineering. Comparisons with conventional boiler/steam turbine systems are included.

Impact and feasibility of a membrane pre-concentration step in kraft recovery

TAPPI Journal ◽  
2021 ◽  
Vol 20 (5) ◽  
pp. 331-340
Author(s):  
MAX KLEIMAN-LYNCH ◽  
DIEGO F. RIVERA ◽  
STEPHEN H. FRAYNE ◽  
BRENT D. KELLER
Keyword(s):  
Energy Savings ◽  
Black Liquor ◽  
Pulp Mill ◽  
Membrane System ◽  
Operating Parameters ◽  
Clean Water ◽  
Membrane Systems ◽  
Mechanical Pressure ◽  
In Series ◽  
Concentration Step

Emerging robust membrane systems can perform the first section of black liquor (BL) concentration by separating clean water from the black liquor stream using only mechanical pressure. By doing so, they can reduce the steam and energy required for BL concentration. Because of the high osmotic pressure of strong BL, a membrane system would not replace evaporators but would operate in series, performing the first section of BL concentration. In this work, we use a multi-effect evaporator (MEE) model to quantify the steam and energy savings associated with installing membrane systems of different sizes. When maintaining a constant BL solids throughput, we find that a pulp mill could reduce steam usage in its evaporators by up to 65%. Alternatively, a membrane system could also serve to increase BL throughput of the recovery train. We find that a membrane system capable of concentrating BL to 25% could double the BL solids throughput of a mill’s evaporators at the same steam usage. We also demonstrate that installing a membrane system before an MEE would minimally affect key operating parameters such as steam pressures and BL solids concentrations in each effect. This indicates that installing a membrane pre-concentration system would be nonintrusive to a mill’s operations.

Brownstock washing: A review of the literature

TAPPI Journal ◽  
2014 ◽  
Vol 13 (1) ◽  
pp. 9-19 ◽  
Author(s):  
RICARDO B. SANTOS ◽  
PETER W. HART
Keyword(s):  
High Efficiency ◽  
Black Liquor ◽  
Material Balance ◽  
Kraft Pulping ◽  
Wash Water ◽  
Pulp Fibers ◽  
Kraft Process ◽  
Cooking Process ◽  
Materials Used ◽  
Entrapped Air

Brownstock washing is a complex, dynamic process in which dirty wash water or weak black liquor (dissolved organic and inorganic material obtained from the pulp cooking process) is separated from pulp fibers. The use of material balance techniques is of great importance to identify potential problems and determine how well the system is operating. The kraft pulping industry was the first known to combine pulp washing with the recovery of materials used and produced in the wood cooking process. The motivation behind materials recovery is economic, and more recently, environmentally driven. The chemicals used in the kraft process are expensive as compared to those used in the sulfite process. For the kraft process to be economically viable, it is imperative that a very high percentage of the cooking chemicals be recovered. To reach such high efficiency, a variety of washing systems and monitoring parameters have been developed. Antifoam additives and processing aids have also played an important role in increasing washing effectiveness. Antifoam materials help attain washing effectiveness by preventing entrapped air from forming in the system, which allows for an easier, unimpeded flow of filtrate through the screens and washers.

scholarly journals THE FUTURE OF PASSENGER AIR TRANSPORT – VERY LARGE AIRCRAFT AND OUT KEY HUMAN FACTORS AFFECTING THE OPERATION AND SAFETY OF PASSENGER AIR TRANSPORT

2017 ◽  
Vol 12 ◽  
pp. 104
Author(s):  
Petra Skolilova
Keyword(s):  
Human Factors ◽  
Human Error ◽  
Operating Cost ◽  
Aircraft Design ◽  
Air Transport ◽  
Final Decision ◽  
Factors Affecting ◽  
Fuel Burn ◽  
The Future ◽  
The Impact

The article outlines some human factors affecting the operation and safety of passenger air transport given the massive increase in the use of the VLA. Decrease of the impact of the CO2 world emissions is one of the key goals for the new aircraft design. The main wave is going to reduce the burned fuel. Therefore, the eco-efficiency engines combined with reasonable economic operation of the aircraft are very important from an aviation perspective. The prediction for the year 2030 says that about 90% of people, which will use long-haul flights to fly between big cities. So, the A380 was designed exactly for this time period, with a focus on the right capacity, right operating cost and right fuel burn per seat. There is no aircraft today with better fuel burn combined with eco-efficiency per seat, than the A380. The very large aircrafts (VLAs) are the future of the commercial passenger aviation. Operating cost versus safety or CO2 emissions versus increasing automation inside the new generation aircraft. Almost 80% of the world aircraft accidents are caused by human error based on wrong action, reaction or final decision of pilots, the catastrophic failures of aircraft systems, or air traffic control errors are not so frequent. So, we are at the beginning of a new age in passenger aviation and the role of the human factor is more important than ever.

The Impact of the Nicaragua Case on Matters of Evidence and Fact-Finding

2012 ◽  
Vol 25 (1) ◽  
pp. 149-156
Author(s):  
PAUL S. REICHLER
Keyword(s):  
United States ◽  
Armed Conflict ◽  
The United States ◽  
Pulp Mills ◽  
Government Officials ◽  
The Government ◽  
Fact Finding ◽  
Day To Day Operations ◽  
High Level ◽  
The Impact

AbstractThe Nicaragua case demonstrates the Court's competence in receiving and interpreting evidence, and in making reasoned findings of fact, even in the most complicated evidentiary context, as is often presented in cases involving use of force and armed conflict. The Court applied well-established standards for evaluating the conflicting evidence presented to it. In particular, the Court determined that greater weight should be given to statements against interest made by high-level government officials than to a state's self-serving declarations. The Court also determined that statements by disinterested witnesses with first-hand knowledge should receive greater weight than mere statements of opinion or press reports. In applying these guidelines, the Court found, correctly, that (i) the United States had used military and paramilitary force against Nicaragua both directly and indirectly, by organizing, financing, arming, and training the Contra guerrillas to attack Nicaragua; (ii) the evidence did not support a finding that the United States exercised direct control over the Contras’ day-to-day operations; and (iii) there was no evidence that Nicaragua supplied arms to guerrillas fighting against the government of El Salvador during the relevant period, or carried out an armed attack against that state. While Judge Schwebel's dissent criticized the last of these findings, in fact, the evidence fully supported the Court's conclusion. In subsequent decisions during the past 25 years, the Court has continued to rely on the approach to evidence first elaborated in the Nicaragua case and has continued to demonstrate its competence as a finder of fact, including in cases involving armed conflict (Bosnia Genocide) and complex scientific and technical issues (Pulp Mills).

Pulp mill process closure: a review of global technology developments and mill experiences in the 1990s

2004 ◽  
Vol 50 (3) ◽  
pp. 183-194 ◽  
Author(s):  
S.C. Stratton ◽  
P.L. Gleadow ◽  
A.P. Johnson
Keyword(s):  
Manufacturing Industry ◽  
Pollution Prevention ◽  
Optimal Solution ◽  
Pulp Mill ◽  
Thermomechanical Pulp ◽  
Pulp Mills ◽  
Oxygen Delignification ◽  
Manufacturing Operations ◽  
The Impact ◽  
Mill Process

The impact of effluent discharges continues to be an important issue for the pulp manufacturing industry. Considerable progress has been made in pollution prevention to minimize waste generation, so-called manufacturing “process closure.” Since the mid-1980s many important technologies have been developed and implemented, many of these in response to organochlorine concerns. Zero effluent operation is now a reality for a few bleached chemi-thermomechanical pulp (BCTMP) pulp mills. In kraft pulp manufacturing, important developments include widespread adoption of new cooking techniques, oxygen delignification, closed screening, improved process control, new bleaching methods, and systems that minimize pulping liquor losses. Coupled to this is a commitment to reduce water use and maximize reuse of in-mill process streams. Some companies pursued bleach plant closure, and many have been successful in eliminating a portion of their bleaching wastewaters. However, the difficulties inherent in closing bleach plants are considerable. For many mills the optimal solution has been found to be a high degree of closure coupled with external biological treatment of the remaining process effluent. No bleach plants at papergrade bleached kraft mills are known to be operating effluent-free on a continuous basis. This paper reviews the important worldwide technological developments and mill experiences in the 1990s that were focused on minimizing environmental impacts of pulp manufacturing operations.

Purification of pulp mill condensates by an adsorptive process on activated carbon

Holzforschung ◽  
2019 ◽  
Vol 73 (6) ◽  
pp. 589-597 ◽  
Author(s):  
José A.F. Gamelas ◽  
Sofia M. Rebola ◽  
Margarita G. Evtyugina ◽  
Valdemar I. Esteves ◽  
Dmitry V. Evtuguin
Keyword(s):  
Activated Carbon ◽  
Volatile Compounds ◽  
Water Cycle ◽  
Black Liquor ◽  
Pulp Mill ◽  
Dimethyl Disulfide ◽  
Pulp Mills ◽  
Wide Range ◽  
New Process ◽  
Pseudo Second Order

Abstract In order to close the water cycle in pulp mills with condensates instead of fresh water, the malodorous/hazardous volatile compounds and colored substances have to be removed by appropriate efficient methods. In the present work, the condensate from the evaporation of black liquor (BL) from a kraft mill was purified by a batch adsorptive process by means of commercial activated carbon (AC). The effluent was found to contain a wide range of aromatic and organosulfur volatile compounds, including toluene, ethylguaicol, syringaldehyde, dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), 2,3-dimethylthiophene, benzothiol and benzothiophene derivatives. Methanol was the major volatile organic component in the condensate (201 mg l−1), which was, however, poorly adsorbed on the AC surface. Aromatics and organosulfur contaminants were adsorbed almost completely in 2–5 min at 23°C under the optimized AC load (900 mg l−1). The treatment allowed the elimination of up to 99% of the obnoxious odor, color and turbidity of the condensate. The adsorption equilibrium followed the Langmuir model and the pseudo-second-order kinetics. The new process could be incorporated in the pulp mill with relatively low additional reagent costs.

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