Reducing energy costs during solvent regeneration at the tar deasphalting unit

For propane tar deasphalting units, a rather high energy intensity of the technological process is characteristic. In order to reduce it, an assessment was made of the possibility of reducing the steam consumption during the regeneration of propane from asphalt solution. The study was carried out using a Honeywell UniSim Design modeling system, in which a model of a propane tar deasphalting unit was formed. The Peng-Robinson method was used as a mathematical package for calculating the thermodynamic properties of the components of the fractions. The component composition of the feedstock is represented by oil fractions with boiling points from 405 to 616 °C. When carrying out a computational experiment, the following values of technological parameters were used: the tar consumption was 38.9 t / h, the ratio (propane: raw material) was (6.4: 1), the yield of deasphalted oil was about 30 wt%. The performed analysis of a typical scheme for the regeneration of propane from asphalt solution showed that in the process stream supplied to the feed of the stripping column K-6, there is already a sufficiently large amount of a vapor phase consisting practically of propane and traces of oil fractions. To efficiently use the energy of the flow without attracting additional energy costs, it is advisable to separate the gas and liquid phases before they enter the column K-6, that is, to include an additional separator in the technological scheme before it. The performed computational experiment showed that in the proposed version of the technological scheme, the steam consumption required for the release of propane decreases by 17.5%, which, accordingly, for the subsequent devices of the scheme, reduces the amount of water discharged into the sewage system. Optimization of technological modes of the stripping column K-6 provides a clear separation of propane, in the flow of which the content of bitumen fractions is 0.03 mol%, which makes it possible in industrial conditions to return the flow of propane to the feed of the extraction column. The proposed technological solution for propane recovery can be used in the processes of one- and two-stage tar deasphalting.

IMPACTS OF BUILDING FUNCTION ON NORMALIZED-STEAM CONSUMPTION: ANALYSIS OF FLOOR AREA NORMALIZATION VERSUS LINEAR REGRESSION ON HEATING DEGREE-DAYS IN A HEATING-DOMINATED CLIMATE

ABSTRACT Linear regression analysis is one the most common methods for weather-normalizing energy data, where energy versus degree-days is plotted, quantifying the impacts of outside temperature on buildings’ energy use. However, this approach solely considers dry-bulb temperature, while other climate variables are ignored. In addition, depending on buildings’ internal loads, weather impact can be less influential, making the linear regression method not applicable for energy data normalization in internally driven buildings (such as research laboratory buildings, healthcare facilities, etc.). In this study, several existing buildings from different categories, all located on the University of Massachusetts Amherst campus and exposed to the same weather conditions in a heating-dominated climate, were analyzed. For all cases, regression of monthly steam use on heating degree-days and floor-area normalized steam data were used, investigating applicability of the former when the latter changes. It was found that internal loads can skew steam consumption, depending on the building functionality, making the effect of degree-days negligible. For laboratory-type buildings, besides heating and domestic hot water production, steam is also used for scientific experiments. Here, daily occupancy percentage, even during weekends and holidays, was higher than that of other buildings, indicating the intensity of scientific experiments performed. This significantly impacted steam consumption, resulting in higher floor-area-normalized steam usage. In these cases, steam use did not provide an outstanding correlation to heating degree-days. Whereas, for cases with other functionality-types and lower floor-area normalized steam, coefficients of determination in regressions were high. This study concludes that even for buildings located in the same climate, depending on how building functionality and occupancy schedule influence floor-area normalized steam use, multivariate linear regression can provide more accurate analysis, rather than simple linear regression of steam on heating degree-days.

Innovation in a Continuous System of Distillation by Steam to Obtain Essential Oil from Persian Lime Juice (Citrus latifolia Tanaka)

The citrus industry is one of the most important economic areas within the global agricultural sector. Persian lime is commonly used to produce lime juice and essential oil, which are usually obtained by batch distillation. The aim of this work was to validate a patented continuous steam distillation process and to both physically and chemically characterize the volatile fractions of essential Persian lime oil. Prior to distillation, lime juice was obtained by pressing the lime fruit. Afterwards, the juice was subjected to a continuous steam distillation process by varying the ratio of distillate flow to feed flow (0.2, 0.4, and 0.6). The distillate oil fractions were characterized by measuring their density, optical rotation, and refractive index. Gas chromatography GC-FID was used to analyze the chemical compositions of the oil fractions. The process of continuous steam distillation presented high oil recovery efficiencies (up to 90%) and lower steam consumption compared to traditional batch process distillation since steam consumption ranged from 32 to 60% for different steam levels. Moreover, a reduction in process time was observed (from 8 to 4 h). The oil fractions obtained via continuous steam distillation differed significantly in their composition from the parent compounds and the fractions.

Heat Integration of an Industrial Unit for the Ethylbenzene Production

This paper presents both the results of a study of the existing heat exchanger network (HEN) of an industrial unit for ethylbenzene (EB) production by the alkylation of benzene with ethylene, and an analysis of four different HEN retrofit projects carried out using process integration methods. The project of modernization of HEN was carried out using classical methods of Pinch analysis. For this case, the value of ΔTmin is determined, which is limited by the technological conditions of the process. Additionally, two different heat pump (HP) integration options and the joint retrofit Pinch project with HP integration are under consideration. The economic analysis of each of the projects was carried out. It is shown that the best results will be obtained when implementing the joint project. As a result, steam consumption will be reduced by 34% and carbon dioxide emissions will be decreased by the same amount.

Improving the massecuite crystallization in sugar production

The article discusses the concepts of continuous vacuum apparatus operation: vertical VKT (VKT – Verdampfungs-Kristallisations-Turm) and horizontal cascade of VKH vacuum apparatus (VKH —horizontal vacuum pan) from BMA (Germany). The advantages and features of the vertical continuous vacuum apparatus VKT are shown, as well as the possibilities for increasing the efficiency of the product department of sugar factories. Thanks to the special design of the crystallization chambers, the low massecuite level above the heating chamber and the use of mechanical stirrers in each chamber, the VKT apparatus can operate without difficulty with a very small temperature difference between heating steam and massecuite, as well as with an absolute heating steam pressure well below 1 bar. With optimal use of VKT vacuum apparatus, a variety of energy-saving schemes can be implemented, for example, double-effect evaporation in the crystallization section. Part of the secondary crystallization steam is used to heat one of the VKT units, which saves the heating steam of the evaporator unit used for this purpose. With an increase in the productivity of the sugar factory, it is possible to quickly equip the VKT apparatus with an additional chamber. The device works continuously throughout the season, especially with products with massecuite purity of more than 94%. The chambers are cleaned without stopping the entire apparatus. The boiling of massecuite of all stages of crystallization in VKT devices ensures a uniform operating mode of the food compartment, allows to achieve an increase in sugar yield and helps to reduce steam consumption at the plant.

A Method to Reduce Steam Consumption of ECF Bleaching Based on Operation Optimizing

Development of paper industry has been restricted by resources, energy and environment deeply; further reducing energy consumption becomes an urgent problem to be solved. In this paper, the calculating model of steam consumption in bleaching process is established under the premise of ensuring product quality and controlling bleaching cost. Then, an optimization model for minimizing steam consumption is constructed. Compared with before optimization, the steam consumption of the optimized bleaching system reduced by 19.48% (0.5014 t/adt) at a loss of 0.11% brightness (0.1 ISO%) and 5.17% viscosity (33 mL/g). The amount of chemicals should be increased to ensure the quality of the pulp while decreasing the bleaching temperature to reduce steam consumption, the cost of bleaching pulp has decreased by 1.62% (3.19 USD/adt) after optimization. The verification experiments showed all the pulp quality indices can meet the requirements of bleached pulp.

Machine Learning-Based Energy System Model for Tissue Paper Machines

With the global energy crisis and environmental pollution intensifying, tissue papermaking enterprises urgently need to save energy. The energy consumption model is essential for the energy saving of tissue paper machines. The energy consumption of tissue paper machine is very complicated, and the workload and difficulty of using the mechanism model to establish the energy consumption model of tissue paper machine are very large. Therefore, this article aims to build an empirical energy consumption model for tissue paper machines. The energy consumption of this model includes electricity consumption and steam consumption. Since the process parameters have a great influence on the energy consumption of the tissue paper machines, this study uses three methods: linear regression, artificial neural network and extreme gradient boosting tree to establish the relationship between process parameters and power consumption, and process parameters and steam consumption. Then, the best power consumption model and the best steam consumption model are selected from the models established by linear regression, artificial neural network and the extreme gradient boosting tree. Further, they are combined into the energy consumption model of the tissue paper machine. Finally, the models established by the three methods are evaluated. The experimental results show that using the empirical model for tissue paper machine energy consumption modeling is feasible. The result also indicates that the power consumption model and steam consumption model established by the extreme gradient boosting tree are better than the models established by linear regression and artificial neural network. The experimental results show that the power consumption model and steam consumption model established by the extreme gradient boosting tree are better than the models established by linear regression and artificial neural network. The mean absolute percentage error of the electricity consumption model and the steam consumption model built by the extreme gradient boosting tree is approximately 2.72 and 1.87, respectively. The root mean square errors of these two models are about 4.74 and 0.03, respectively. The result also indicates that using the empirical model for tissue paper machine energy consumption modeling is feasible, and the extreme gradient boosting tree is an efficient method for modeling energy consumption of tissue paper machines.

Experimental and Theoretical Study of Heat Losses in Drying Cylinders

The research purpose is to develop methods for determination of heat losses in drying cylinders. Experimental study of temperature of drying cylinders performed in the drying section of a paper machine during its steady-state operation. Medium, maximum and permissible statistical characteristics of drying cylinder temperatures were defined. The drying cylinders with increased condensation concentration were determined by the minimally permissible temperature levels and the repair of the condensation drainage system to reduce heat losses (steam consumption) was justified. The cause of uneven dryness of the paper web across the width has been determined. The condensate ring on the inner wall at the edges of the drying cylinders gets thickened due to moisture coming from the end caps from the action of centrifugal forces. The condensation is removed from the drying cylinders with a siphon on the drive side. Therefore, on the front side of the drying cylinders condensate film has a greater thickness, and the paper web dries worse. The single-sided condensate disposal and the physical effect of centrifugal condensate runoff from the end caps to the side inner surface of the drying cylinders cause a lower dryness from the front side of the paper web. The use of thermal insulation of end caps will contribute to uniform dryness across the width of the paper web. The results of experimental studies were processed by methods of mathematical statistics in order to describe the thermal losses during contact drying of the paper web on drying cylinders with and without thermal insulation of the end caps to the ambient air. The calculation of heat losses is carried out according to the refined method of researching thermal processes in contact drying of paper web. It is found, that the use of thermal insulation of the end caps of the drying cylinders provides a reduction in steam consumption for contact drying of the paper web without affecting the technological process. The research results can be used to reduce heat losses in the drying section of paper machines on cylinders that do not have thermal insulation of the end caps. For instance, for a paper machine consisting of 56 cylinders with a diameter of 1500 mm and a capacity of 7000 kg/h of absolutely dry paper, insulating their end caps saves up to 223 kg/h of steam for drying the paper web. Methods of detection of drying cylinders with increased content of condensation on permissible levels of temperature is developed and approved. A refined method for determining thermal losses during contact drying of the paper web on drying cylinders has been developed.

Development of converging-diverging multi-jet nozzles for molten smelt shattering in kraft recovery boilers

The effective shattering of molten smelt is highly desired in recovery boiler systems. Ideally, shatter jet nozzle designs should: i) generate high shattering energy; ii) create a wide coverage; and iii) minimize steam consumption. This study proposes a novel converging-diverging multi-jet nozzle design to achieve these goals. A laboratory setup was established, and the nozzle performance was evaluated by generating jet pressure profiles from the measurement of a pitot tube array. The results show that the shatter jet strength is greater with a large throat diameter, high inlet pressure, and a short distance between the nozzle exit and impingement position. Increasing the number of orifices generates a wider jet coverage, and the distance between the orifices should be limited to avoid the formation of a low-pressure region between the orifices. The study also demonstrates that an optimized converging-diverging multi-jet nozzle significantly outperformed a conventional shatter jet nozzle by achieving higher energy and wider coverage while consuming less steam.