Application of extraction steam graded heat storage in peak shaving of condensing units

In order to alleviate the peak shaving pressure of power grid and further improve the deep peak shaving capacity of coal-fired units, this paper applies staged heat storage to condensing units. Under the condition of constant boiler load, the heat of regenerative steam extraction is stored to reduce the electrical load output of the unit. Taking a 660MW ultra-supercritical unit as an example,30%THA,40%THA and 50%THA were taken as the initial conditions of heat storage respectively to discuss the peak shaving range and power regeneration efficiency of different extraction steam positions for heat storage. The results show that the “storage 1# HP heater extraction steam” scheme with “two-stage three tank” heat storage and release structure has the largest peak shaving range of 37.3%~56.9% under 50% initial conditions. When the “two-stage three tank” heat storage and release structure selects the “storage 1# HP heater extraction steam ”scheme under 40% initial working condition, the “power regeneration efficiency” reaches the highest——78.3%. And the “power regeneration efficiency” of “two stage three tank” storage structure are always higher than the “single-stage” storage structure.

Grape (Vitis vinifera L. cv. País) Juices Obtained by Steam Extraction

Vitis vinifera L. cv. País is an ancestral Chilean grape undervalued due to its undesirable oenological characteristics. In this study, steam extraction for the production of grape juice, a new product, according to our knowledge, is proposed as an alternative for the valorization of this fruit. The effect of the extraction time on the composition and antioxidant capacity of País grape juice obtained was evaluated, as well as the change in the phenolic profile during storage. The soluble solid values and total polyphenol and total anthocyanin content increased with the extraction time. However, a residence time of the juice in the extraction device higher than 10 min led to thermal degradation of anthocyanins and flavonols. The most abundant phenolic compound identified and quantified by HPLC-DAD in the País grape juice was cinnamic acid. The storage of juices had a greater effect on anthocyanin and flavonol losses than the residence time of the juice in the extraction device. The antioxidant capacity of juice measured by ABTS and ferric reducing power assays ranged from 3 to 5 mmol trolox/L and from 10 to 18 mM Fe2+/L, respectively. In summary, steam extraction is a viable method to produce País grape juice with antioxidant capacity.

Alternative wax recovery from Apis mellifera: Different combs size effect

The bee wax has great historical importance and has been present since the evolution of civilizations. Currently, besides several uses of the wax, its recovery is indispensable for the rational management of swarms by beekeepers. The wax can be recovered from the combs using different techniques, however the conditions of the pre-extraction combs, such as their size, can influence the wax yield. Thus, studies must still be carried out to standardize the techniques and processes for extracting the wax from the combs, in order to improve the wax yield. This study aimed to evaluate the recovery of Apis mellifera wax according to the size of the comb using an alternative extraction technique. First, the influence of the comb size on wax recovery was evaluated. We used brown color combs, which were broken down into four sizes, each size representing a treatment, namely: Treatment I - 25 cm2; Treatment II - 16 cm2; Treatment III - 9 cm2 and Treatment IV - 4 cm2. Combs were submitted to the "internal strain" technique for 30 minutes of extraction, after boiling the water. The wax recovery was superior in treatment III (P <0.05). Wax recovery from treatment IV was similar to treatment II, which, in turn, showed similar recovery to treatment I (P <0.05). Besides, the wax recovery using 9 cm2 combs was evaluated by the commercial technique of "steam extraction" and the alternative technique of "internal strain", for a period of 30 minutes. The “internal strain” technique showed greater wax recovery than the “steam extraction” technique (P <0.01). The use of alternative wax recovery together with 9 cm2 combs size may optimize the wax extraction process, in terms that it decreases the time of exposure of the wax to heat, and thus positively affect the quality of the final product.

Chemical, Microbiological and Sensory Stability of Steam Extracted Jaboticaba (Myrciaria jaboticaba) Juice

Jaboticaba (Myrciaria jaboticaba) is a Brazilian berry rich in phenolic compounds, much appreciated for its sweet and slightly acid taste, and highly perishable. Thus, we aimed at producing jaboticaba juice by steam extraction and at investigating its microbiological, sensorial and chemical qualities during storage for up to 168 days. Juice was microbiologically safe and even though unsweetened juice was well accepted, sucrose addition further improved flavor (21%), overall impression (11%) and purchase intent (21%) scores. Cyanidin-3-O-glucoside (C3G) was the major phenolic (40%), followed by gallic (28%) and ellagic acids (21%). Total phenolics contents decreased from 27% (50 °C) to 50% (25 °C), mainly driven by C3G degradation. At 60 °C, total phenolics contents did not change after 42 days since C3G degradation was counterbalanced by gallic acid formation (129%), which followed zero-order reaction kinetics. Anthocyanins degradation followed first-order reaction kinetics (C3G half-life at 25 °C = 21.7 days) and was associated with color changes during storage. In conclusion, steam extraction followed by hot-filling technique ensured a juice with at least six months of shelf life.

On the rational form of rotary control diaphragms for steam turbines with industrial and cogeneration steam extraction

The Russian park of power steam turbines contains a large number of turbines with adjustable steam extraction from the flow path where rotary control diaphragms are used as flow controllers, which structurally easily fit into the flow path of these turbines. This method of regulating the steam flow rate is accompanied by a decrease in the efficiency of the subsequent stages of the turbine and causes the appearance, at reduced loads, of additional disturbing forces acting on the rotor blades. In the presented materials, a variant of a post-sampling stage with a radial rotary control diaphragm is considered. The performed mathematical modeling of the working fluid flows in such a stage showed that in this case, at all turbine loads, a relatively uniform velocity field is provided when steam enters the nozzle apparatus, which naturally entails the elimination of the noted drawbacks.

The invasive alien species Amorpha fruticosa in Bulgaria and its potential as economically prospective source of valuable essential oil

The high tolerance of various habitat conditions and potent propagation ability of Amorpha fruticosa L. (Fabaceae) promote its aggressive invasive behaviour. The aim of this study is to evaluate 1) several populations of this plant by the potential yield of the fruit, 2) the approximate yield of the essential oils, and 3) composition of the essential oil. The potential yield of fruit is evaluated based on extrapolations of weight and number of fruits per infrutescence, number of infrutescences per plant and number of individuals per population. Steam extraction of the essential oil was performed and GS/MS analysis of the composition of the essential oil. The populations on our key plots are big enough for harvesting with fruit/infrutescence 152 ±15 (n = 20) and infrutescences/shrub 436 ±157 (n = 20). The yield is 0.83 ml/100g. We identified 22 components with major constituents caryophyllene (17.64%) α-guaiene (14.70%), naphthalene (6.75%), γ-muurolene + (5.98%).

Optimization of Extraction Position Under Low Loads Operation of Power Plant in Power-Water Cogeneration

Power-water cogeneration is an effective mode to address fresh water shortage problem, namely low-temperature multi-effect seawater desalination (LT-MED) system coupled with thermal power plant. In the present study, the steam extraction position of thermal vapor compressor (TVC) under different loads was optimized to reduce the cost of water production. And then, the thermodynamic performance of the coupled system is obtained when the extraction position of motive steam varies from No.5 to No.7, whereas the power plant load is in the range of 30% THA – 50% THA. The results indicate that the optimal extraction position is not fixed under different low loads of the power plant, it depends on the cost calculation methods. For any method used to calculate the steam cost, the optimal steam extraction position is from No.5 extraction when the power plant load is 40%THA. The optimal steam extraction position is from No.6 extraction when the power plant load is 30%THA. And the optimal steam extraction position is from No.7 extraction when the power plant load is 30%THA.