563. The steam stripping of taints from liquids. II. Counterflow stripping with particular reference to possible use of Vacreator equipment

1954 ◽  
Vol 21 (3) ◽  
pp. 370-382 ◽  
Author(s):  
J. K. Scott
Keyword(s):  
Considerable Increase ◽  
Waste Heat ◽  
Contact Process ◽  
Graphical Methods ◽  
Steam Consumption ◽  
Stripping Steam ◽  
Feed Temperature ◽  
Single Contact

The considerable increase in efficiency of taint removal which can be attained by counterflow methods is shown by the extension of the algebraic and graphical methods of Part I and confirmed by experiments with the reference substances diacetyl and acetoin in water. The treatment is mainly confined to multiple contact counterflow, and several methods are suggested by which existing Vacreator equipment may be used for counterflow connexion. The effect of a feed temperature below the temperature existing in the contacting vessels is shown to increase the amount of taint removal per pound of stripping steam used. Comparative curves are given for total steam consumption for systems preheating to various temperatures with waste heat.Results are given for experiments with a converted small size Tandem Vacreator. For diacetyl, the stripping steam used was one-tenth of that for a single contact process over the same range of diacetyl removal. Acetoin, being less volatile than diacetyl, did not show the same large steam saving.

562. The steam stripping of taints from liquids. I. An analysis of processing methods with particular reference to the Vacreator

1954 ◽  
Vol 21 (3) ◽  
pp. 354-369 ◽  
Author(s):  
J. K. Scott
Keyword(s):  
Equilibrium Constant ◽  
Infinite Number ◽  
Equilibrium Constants ◽  
Maximum Efficiency ◽  
Graphical Methods ◽  
Processing Methods ◽  
Volatile Substances ◽  
Single Contact

The operation of equipment for reducing the amounts of volatile taints in liquids by the use of open or generated steam is explained and analysed. From consideration of material balances for each system and the equilibrium characteristics of the volatile substances, formulae and graphical methods are derived and used to show the degree of taint removal which can be attained by the steam. The methods and charts are used to show the performance of Tandem and Triple Vacreators. The methods presented in the paper can be used for any volatile solute but particular reference is made to two substances having equilibrium constants of 17 and 1·4 because these represent a range of volatilities of particular interest and are approximate values for diacetyl and acetoin which can be used as reference substances.The effectiveness of any system is shown to depend on the value of a stripping factor which is equal to the product of the equilibrium constant and the pounds of deodorizing steam per lb. of liquid (i.e. F = mV/L). The efficiency of methods where the liquid is contacted several times with fresh steam is shown to be much greater than for single contact. The gain in efficiency for each stage becomes less pronounced with increasing contacts and the maximum efficiency is shown to be limited even for an infinite number of contacts.

Thermo-Economic Analysis of an Integrated Supercritical CO2 Brayton Cycle and Multiple Effect Desalination Systems

2018 ◽  
Author(s):  
Sattam Alharbi ◽  
Mohamed L. Elsayed ◽  
Louis Chow
Keyword(s):  
Economic Analysis ◽  
Waste Heat ◽  
Electrical Power ◽  
Production Capacity ◽  
Hot Water ◽  
Performance Ratio ◽  
Specific Power ◽  
Brayton Cycle ◽  
High Feed ◽  
Feed Temperature

A thermo-economic analysis is carried for the current integrated supercritical carbon dioxide (sCO2) Brayton cycle with both multi-effect desalination coupled with mechanical vapor compression (MED-MVC) and conventional MED system. The conventional MED system uses hot water as the heat source by recuperating the waste heat from the sCO2 cycle. The MED-MVC system uses a vapor compressor to eliminate the need to condense the water vapor in the last effect of the MED system. The advantage of the MED-MVC is the ability to recuperate part of the waste heat of the sCO2 cycle through preheating the seawater feed directed to the first effect. Forward feed configuration is selected since high feed temperature can be accommodated for the MED-MVC. On the other hand, in the case of conventional MED, high feed temperature is limited to the last effect temperature. To satisfy the demand of approximately 2,500 families, the water production capacity is 1,250 m3/day, and 20 MW of electrical power is needed. The electrical power generated from the sCO2 cycle is also used to drive the MVC unit and operate the feed, brine and distillate pumps in the MED system. Results reveal that both MED and MVC systems are capable to achieve the selected production capacity. The specific power consumption, universal performance ratio, and total water price for MED systems are 1.22 kWh/m3, 56.51 and 0.69 $/m3, respectively; whereas the MED-MVC systems are 10.22 kWh/m3, 27.35 and 0.84 $/m3, respectively. The cost of electricity is 0.029 $/kWh.

scholarly journals Waste heat potentials in the drying section of the paper machine in Umka Cardboard Mill

2011 ◽  
Vol 15 (3) ◽  
pp. 735-747 ◽  
Author(s):  
Goran Jankes ◽  
Nikola Tanasic ◽  
Mirjana Stamenic ◽  
Vuk Adzic
Keyword(s):  
Thermal Efficiency ◽  
Energy Use ◽  
Waste Heat ◽  
Paper Industry ◽  
Ventilation System ◽  
Specific Energy Consumption ◽  
Paper Machine ◽  
Steam Consumption ◽  
Drying Section ◽  
Heat Released

Paper production is one of the most energy intensive industrial processes. The use of waste heat is very important for energy efficiency improvement in paper industry. This paper deals with methods for calculation of potentials of waste heat generated in paper/board production process. For that purpose, the material and heat balance of the cardboard machine at Umka Cardboard Mill has been determined. Field measurements were conducted in order to define the unknown values of process parameters used for calculation in the balance equations and modelling. The focus was given to the cardboard drying section, which consumes most of the energy supplied to the machine. Additional aim of the work presented in the paper was to evaluate the specific energy consumption and the thermal efficiency of all individual energy units within the machine?s drying section. The results indicate two main sources of waste heat: waste heat released to the atmosphere with the discharge air from the present waste heat recovery system (14,380 kW); and waste heat released into the hall from the machine and extracted by the hall ventilation system (4,430 kW). Waste heat from both sources is characterized by fairly low temperatures 58-75?? and fairly high moisture content (30-40 g/kg). The waste heat can be partly utilized for preheating the fresh air in cardboard drying process, saving up to 13% of steam consumption. The specific heat consumption and specific steam consumption (consumption per tonne of produced cardboard) of the machine was 1,490 kWh/t and 1.4 t/t, respectively. The thermal efficiency of drying section and coating drying section was 55.6% and 33.6%, respectively. All these figures imply necessity for further waste heat utilization with the aim of improving the efficiency of energy use.

Optimization of elemental chlorine-free bleaching for a softwood kraft pulp • part 2: economic analysis of chemical and steam consumption

TAPPI Journal ◽  
2010 ◽  
Vol 9 (9) ◽  
pp. 47-53 ◽  
Author(s):  
BRIAN N. BROGDON
Keyword(s):  
Chlorine Dioxide ◽  
Previous Investigation ◽  
Kraft Pulp ◽  
Energy Costs ◽  
Alkaline Extraction ◽  
Stage Versus ◽  
Kraft Pulps ◽  
Steam Consumption ◽  
Elemental Chlorine ◽  
Softwood Kraft Pulp

Our previous investigation [1] re-analyzed the data from Basta and co-workers (1992 TAPPI Pulping Conference) to demonstrate how oxidative alkaline extraction can be augmented and how these changes affect chlorine dioxide consumption with elemental chlorine-free (ECF) sequences. The current study manipulates extraction delignification variables to curtail bleaching costs with a conventional U.S. Southern softwood kraft pulp. The economic advantages of ~0.35% to 0.65% H2O2 peroxide reinforcement in a 70°C (EOP)-stage versus 90°C (EO)-stage are predisposed to the brightness targets, to short or long bleach sequences, and to mill energy costs. Minimized bleaching costs are generally realized when a 90°C (EO) is employed in D0(EO)D1 bleaching, whereas a 70°C (EOP) is economically advantageous for D0(EOP)D1E2D2 bleaching. The findings we disclose here help to clarify previous ECF optimization studies of conventional softwood kraft pulps.

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