EFFICIENCY OF THE NOZZLES OF CONTACT HEAT EXCHANGERS

At powerful thermal power plants or boiler houses, the efficiency depends to the greatest extent on the amount of heat lost with the cooling of turbine condensers, exhaust gases that have a high temperature. Each type of such losses is a large unused energy potential, that is, a secondary energy resource that can be used. At the same time, the use of secondary resources and industrial emissions will improve the ecological situation in the regions, and this has always been an urgent task. As a rule, large losses of thermal secondary energy resources in boilers are reduced by installing economizers and air heaters. Contact types of heat exchangers are distinguished by the best efficiency in operation. In contact economizers, to increase the surface of heat and mass transfer, it is advisable to use various types of nozzles. The aim of the study is to develop such an indicator, with which it is possible to determine the optimal type of nozzle of the contact economizer installed after the steam boiler. This indicator should show the highest heat engineering efficiency of the packing with a small hydraulic resistance of the heat exchanger. By using the coefficient of specific energy efficiency of the packing in the heat exchanger of waste gases of heating equipment, it is possible to analyze the work of the packing space from the standpoint of thermal and hydraulic efficiency and select the optimal type of packing for each individual unit or installation. Geometric parameters determine the required volume of the apparatus and the hydraulic resistance of the exhaust gases movement. The hydraulic resistance affects the consumption of electrical energy for the drive of smoke exhausters for sucking off exhaust gases from heat engineering installations through the free section of the heat exchanger. Taking into account the developed indicator of the specific energy efficiency in waste heat utilizers, it is possible to select such a type of packing, at which the optimal level of waste heat utilization will be achieved.

Secondary Energy Sources and Their Optimization in the Context of the Tax Gap on Petrol and Diesel

This paper presents an energy management strategy for secondary energy sources and their optimization in the context of the tax gap on mineral oils represented by the tax gap on petrol and diesel. Energy companies face drastic economic and environmental challenges; therefore, this area necessarily requires the setting up of transparent economic instruments and, of course, production. The tax gap in VAT collection represents the gap between how much the state could potentially collect from VAT in accordance with the law and how much VAT really comes into the state coffers. The loss of tax revenues is caused by unpaid and undeclared tax liability. The Estimation of the Gap on Corporate Tax in Slovakia is a pilot project of the International Monetary Fund (IMF) in cooperation with the Institute for Financial Policy (IFP). The results present the estimation of the tax gap within a two-year delay. It is necessary to consider the estimation of the tax gap in the last two years as preliminary due to possible revisions of the national accounts data. Estimations of the tax gap from 2010 to 2017 indicate a decreasing trend. The significant part of the tax gap decrease can be observed from 2014. The main factor, which determines this decrease, is the improving condition of the Slovak economy. From the point of view of the tax gap, the volume of losses is decreasing and the volume of profit, from which the tax is paid, is increasing.

Design of an auger thermo-radiation dryer for drying plant-derived pomace

This paper reports the improved model design of an auger thermo-radiation dryer for drying plant-derived pomace under a low-temperature mode (35...80 °C) to the resulting moisture content at the level of 8...13 % of solids. The dryer has an adjustable speed of auger rotation (3...4 min–1), of airflow (0.05...0.09 m/s), and is characterized by the uniform distribution of heat flux. It is equipped with an energy-saving two-circuit complex that utilizes secondary energy to heat primary air from 21.1 °C to 28.9 °C. The use of Peltier elements, installed at the heating technical surface of the dryer's auger, makes it possible to convert thermal energy into a low-voltage supply voltage for the autonomous supercharger and exhaust fans. The duration of pomace drying in the model structure of the auger thermo-radiation dryer has been determined, in particular tomato pomace, with an initial content of 75 % of solids, which is 107 min. For apple pomace whose starting content of solids is 65 %, it is 98 min. For comparison, the duration of the convective drying of tomato pomace (75 % of solids) is 120 minutes. The drying was carried out at a temperature of 60 °C to the resulting moisture content of 10...12 % of solids. Organoleptic evaluation on the example of tomato pomace confirms the effectiveness of structural solutions in the auger dryer compared to the convective technique. The results reported in this study could create conditions for the further design and implementation of the proposed structure of thermo-radiation dryer for drying plant-derived pomace involving an altered heat supply technique and the utilization of secondary energy. The designed structure of the device makes it possible to process and preserve the quality properties of plant-derived pomace, allowing the use of this product for a wide range of foodstuffs

Expander-generator set for utilization of natural gas overpressure energy

The article deals with the problem of using secondary energy resources in the system of transportation and distribution of natural gas, and the possibility of generating electricity without burning fuel by reducing high-pressure natural gas at gas distribution stations. The analysis of the influence of the gas temperature at the entrance to the expander - generator unit, as well as the dependence of the power of the expander - generator unit on the gas temperature and the temperature of the low-potential source is presented. Optimal temperatures are obtained at which the power of the expander-generator unit is maximal for the given gas parameters.

Modeling an effective method to utilize secondary energy resources of a combined cycle gas turbine based on the CCGT-420T

Nowadays, improving the efficiency of power plants by utilizing secondary energy resources is gaining more attention in the energy sector. In this paper, the combined cycle gas turbine (CCGT-420T) was considered, where exhaust heat from the main and auxiliary equipment is utilized, and sent to a water supply system through a closed-circuit heat exchanger, as a result, the heat transferred ( Q 6.4 MW) is rejected into the environment through a cooling tower. Moreover, an effective modelling method for utilizing heat in a closed cycle, using a steam compressing heat pump unit (HPU) is proposed. In addition, a calculation of the effectiveness of utilizing secondary energy resources depending on the number of HPU stages. In addition, the calculation of the effectiveness of the use of secondary energy resources depending on the number of stages of HPU was carried out. Several options of the model were discussed in this work, such as, two-, three-, and four-stage HPU and the coefficient of performance was calculated. Moreover, the work of these compressors for each option of the model was discussed in this work. Finally, the economic benefits of using of a multi-stage HPU instead of a traditional one-stage HPU during the annual operation of the CCGT-420T was discussed.

MODELING AN EFFECTIVE SOLUTION FOR THE UTILIZATION OF SECONDARY ENERGY RESOURCES OF CCGT UNIT ON THE EXAMPLE OF CCGT-420T CHPP-16

Nowadays, improving the efficiency of power plants by utilizing secondary energy resources is gaining more attention in the energy sector. In this paper, the combined cycle gas turbine (CCGT-420T) was considered, where exhaust heat from the main and auxiliary equipment is utilized, and sent to a water supply system through a closed-circuit heat exchanger, as a result, the heat transferred (Q = 6.4 MW) is rejected into the environment through a cooling tower. Moreover, an effective modelling method for utilizing heat in a closed cycle, using a steam compressing heat pump unit (HPU) is proposed. In addition, a calculation of the effectiveness of utilizing secondary energy resources depending on the number of HPU stages.