ПОВЫШЕНИЕ ЭНЕРГЕТИЧЕСКОЙ И ЭКОЛОГИЧЕСКОЙ ЭФФЕКТИВНОСТИ СИСТЕМ ГАЗООЧИСТКИ НА ТЭС

Energy is the basic sector of the economy and the largest consumer of primary energy resources of any country, which is why the development of world energy is accompanied by global pressure on the environment. The issues are considered of reducing the atmospheric impact of emissions of thermal power plants, improving the reliability and working life of their units, systems, and plants as a whole. The principles are presented of development and improvement of technologies for processing industrial emissions of thermal power plants, the neutralization of which is currently relevant on a regional and global scale. Analysis is carried out of existing methods of cyclone and filtration treatment. An improved design of a cyclone filter is proposed, which allows to increase the reliability of gas turbine and steam-gas units of TPP, while ensuring the efficiency of separation of the suspended part of the flow at the gas treatment point (GTP) of TPP. Similar devices can also be used to increase the degree of cleaning atmospheric emissions released by the TPP coal dust preparation and flue gas systems at coal generation from fi ne particles of PM10 and PM2,5 classes (coal dust and ash), owing to reduction of the size of caught particles from average values for cyclones and wet scrubbers of the order of 5–10 μm to 0.5 μm. The design of the cyclone filter is improved as a result of research of cyclone filtration by methods of Computational Fluid Dynamics (CFD). A system of Reynolds-averaged equations of a single-phase Navier-Stokes flow is used for mathematical modeling of motion in the cyclone filter. To determine the efficiency of separation of the suspended part of the flow in the cyclone filter, the Rercomplex is used obtained by reducing a set comprising the Navier-Stokes equations and the equation of particle motion based on Newton's law to a dimensionless form. Numerical characteristics of the suspension sedimentation from a multiphase flow in a cyclone separator of specified dimensions are found by means of the Rercomplex. The results of bench tests of the proposed design of the cyclone filter are given.

Nowadays, alternative thermodynamic cycles are actively studied. They allow to remove CO2, formed as a result of fuel combustion, from a cycle without significant energy costs. Calculations have shown that such cycles may meet or exceed the most advanced power plants in terms of heat efficiency. The Allam cycle is recognized as one of the best alternative cycles for the production of electricity. Nevertheless, a cycle of compressorless combined cycle gas turbine (CCGT) unit is seemed more promising for cogeneration of electricity and heat. A comparative analysis of the thermal efficiency of these two cycles was performed. Particular attention was paid to ensuring equal conditions for comparison. The cycle of compressorless CCGT unit was as close as possible to the Allam cycle due to the choice of parameters. The processes, in which the difference remained, were analysed. Thereafter, an analysis of how close the parameters, adopted for comparison, to optimal for the compressorless CCGT unit cycle was made. This analysis showed that these two cycles are quite close only for the production of electricity. The Allam cycle has some superiority but not indisputable. However, if cogeneration of electricity and heat is considered, the thermal efficiency of the cycle of compressorless CCGT unit will be significantly higher. Since it allows to independently regulate a number of parameters, on which the electric power, the ratio of electric and thermal power, the temperature of a working fluid at the turbine inlet depend. Thus, the optimal parameters of the thermodynamic cycle can be obtained in a wide range of operating modes of the unit with different ratios of thermal and eclectic powers. Therefore, the compressorless CCGT unit can significantly surpass the best steam turbine and combined cycle gas turbine plants in district heating system in terms of thermal efficiency.

A method for operation study of a compressorless combined-cycle gas turbine (CCCGT) unit during transients from one steady-state mode to another, including during start-up and shutdown, is proposed. As an example, studies of the transients of an energy complex with a capacity of 60 MW are given. A variant of an algorithm concept for start/stop and transients of such an energy complex is proposed. This concept includes algorithms for starting from the three initial states of the energy complex (cold, hot and standby). For these algorithms, the time and energy consumption characteristics are estimated. It is shown that from a cold state, such an energy complex can be started and brought to the nominal mode in 1.5-2 hours. At the same time, the energy costs will not exceed energy consumption for its own needs in a nominal mode. The start-up time from the hot state can be reduced to 20-25 minutes, and the start-up from the standby state can be 2.5-3 minutes. The proposed concept of control algorithms for transient modes is such, so that a temperature state of the main components and parts of the energy complex is provided at a constant temperature. Thus, the time of transients will be determined only by the speed of the regulatory authorities. Consequently, power systems operating on the CCCGT cycle can operate equally efficiently, both in the basic mode and in the power control mode.

Nowadays, thermodynamic cycles are actively studied, in which pure oxygen and fuel are fed into a combustion chamber, and a temperature of a working fluid is regulated by the supply of carbon dioxide and/or water vapor. These cycles are called “oxygen-fuel”. They allow easy to separate CO2, resulting from a fuel combustion, from the working fluid and remove it from the cycle in its pure form. In addition, it has already been shown that an efficiency of electric power generation of such cycles is approaching the best known technologies. However, the efficiency of cogeneration of electricity and heat is more important for many energy systems, especially for Russian, in comparison with the efficiency of electricity generation. The main goal of the study was to analyze the thermal efficiency for cogeneration of electricity and heat of one of the options for the implementation of oxygen-fuel cycles - compressorless combined cycle gas turbine (CCGT) units. A mathematical model of the compressorless CCGT units was developed, which allows to study the thermal performance in a wide range of operating modes. It is conventionally accepted that the system requires a maximum power for power supply of 300 MW, and a maximum power for heat supply of 600 MW. It is assumed that 300 MW of electricity is constantly supplied to the network. In addition, the heat load is provided according to the standard schedule depending on the ambient temperature, and at the same time an averaged data on the temperature of atmospheric air for central Russia over a tenyear period is accepted. The comparison is made with a steam turbine CHP plant and a CCGTCHP plant. The results of the comparison showed a significant advantage of the compressorless CCGT unit.

Energy efficiency simulation of the process of gas hydrate exploitation from flue gas in an electric power plant

In this paper an Organic Rankine cycle is used as waste heat recovery cycle for a 250 x 2 MW thermal power plant. The exhaust flue gas (80 to 130°C) in the thermal power plant is often released into the atmosphere as waste heat. This waste heat can be utilized as a form of heat source for the Organic Rankine Cycle. The treated flue gas form the Flue Gas Desulphurization plant will be fed to the heat exchanger where the heat transfer between the flue gas and the working fluid (e.g.: Ammonia, R245A) will take place. The working fluid will be fed to the (low pressure) turbine where the work done can obtained. After the expansion of the working fluid in the turbine, the working fluid is cooled in the condenser using water. Then this fluid is again sent to the heat exchanger using pump. The flue gas from the heat exchanger after the heat transfer will be then supplied to the stack. The cooling of the condenser water can be done using a cooling tower. As the load varies for the thermal power plant the temperature of the flue gas also changes and hence the turbine shaft output also changes this may result in tripping of the generator. In order to avoid this, a turbine governing system is designed with a step-up gear box and a torque converter. This governing system will keep the generating shaft in motion at constant speed even during low loads and high loads. This cycle will help the thermal power plants to obtain extra power output and will increase the efficiency of the plants.

Dual-fuel combined cycle gas turbine units, including power units on the parallel scheme with predominant coal combustion are considered in the paper. The basic equations for determining the energy efficiency of dual-fuel combined-cycle power units are described. The interdependence of the efficiency of the gas turbine and steam turbine parts of the combined-cycle plant for the efficiency of the combined-cycle plant with a variable binary coefficient is presented. It is shown that 55-56% efficiency is achievable for parallel type combined cycle gas turbine units T with predominant solid fuel combustion on the basis of this interdependence between efficiency and binary coefficient. Comparison of competitiveness in the ratio of fuel prices for gas / coal with traditional coal technology and theoretical rejected combined cycle gas turbine units with an efficiency of 60% for dual-fuel combined cycle gas turbine units with the implementation of the Rankine cycle for subcritical (13 MPa) and supercritical (24 MPa) steam parameters is carried out. It is shown that the dual-fuel combined cycle gas turbine units are preferable to traditional coal steam turbine power units in the case when the ratio of the price of fuel does not exceed 5, binary rejected combined cycle gas turbine units, when the ratio of the prices by more 0,5.

This paper mainly seeks to explore and answer some questions for desulfurization and denitration in thermal power plants in China. Firstly, the desulfurization and denitration technology applicated in the power plant in China at present were analyzed. It is considered that taken combination of the existed technique for purified the pollutants from the thermal power plants, not only lead to the wastage of huge amount of investment, increasing of operating costs, decreasing of the economic benefits, but also add an additional area. It is necessary to develop the integration technology of desulfurization and denitration simultaneously. Secondly the integration technology of desulfurization and denitration at present in China was briefly reviewed such as activated carbon adsorption, SNRB, etc. and most of those at a research stage include the plasma technology. In the third of the paper, the non-thermal plasma technology i.e electron-beam technique, corona discharge and dielectric barrier discharge were discussed. Finally, combined with the actual situation in China, the application prospects of the desulfurization and denitration technology using plasma discharge in the flue gas was bring up. The article also pointed out the barriers need to be overcome if the technology will be applied in power plant, as well as the development direction of desulfurization and denitration technology from flue gas in power plant in China.

Carbon dioxide (CO2) emission from stationary point sources connected to combustion facilities using fossil fuels in addition to other industrial sources is adversely affecting the climate on earth. Thus capturing CO2 from the combustion sources followed by its safe stabilization or storage constitutes an important target. Legion of researches have so far been undertaken to develop absorbents, adsorbents, and membranes to remove CO2 from combustion facilities. Capturing CO2 from the post-combustion flue gas by the chemical absorption method using aqueous ammonia (NH3) has been given serious attention by the researchers considering the advantages of high CO2 capture efficiency, ease of operation, and lower investment cost. Life cycle CO2 emission analysis revealed that capturing CO2 from the exhaust of flue gas of a coal-fired thermal power plant (TPP) using aqueous NH3 could be a plausible option. The possible solid reaction products of aqueous NH3 based multipollutant capture of the flue gas from the TPP targeting for CO2 capture would be ammonium sulfate [(NH4)2SO4], ammonium nitrate [NH4NO3], and ammonium bicarbonate [NH4HCO3]. These products have the potential to serve as N-fertilizer. In this communication, the present status of investigations on the aqueous NH3 based CO2 capture process is analyzed gathering information from the existing literatures. Given the tremendous scope of research in India, the current national research potential could be gainfully utilized for envisaging the CO2 capture by aqueous NH3 in coal-fired TPP. In this regard, multisectoral research programs could be proposed in a planned manner for making use of the available resources in the country with the coordinated approach of few important streams such as academia, thermal power, fertilizer, agriculture, environment, and climate change. Recommendations are made for development of suitable CO2 capture technology in Indian coal-fired TPPs.

The increased requirements to the quality of the water heat conductor for working superhigh (SHP) and supercritical (SCP) pressure power plants and promising units, including combined-cycle gas turbine (CCGT) units and power plants with ultrasupercritical parameters (USCPs), can largely be satisfied through specific electric conductivity and pH measurements for cooled heat conductor samples combined with calculations of ionic equilibria and indirect measurements of several specified and diagnostic parameters. The possibility of calculating the ammonia and chloride concentrations and the total concentration of hardness and sodium cations in the feed water of drum-type boilers and the phosphate and salt contents in boiler water was demonstrated. An equation for evaluating the content of potentially acid substances in the feed water of monotube boilers was suggested. The potential of the developed procedure for evaluating the state of waterchemistry conditions (WCCs) in power plants with CCGT units was shown.

The schemes of a carbon dioxide trigeneration plant using secondary energy resources in the form of products of combustion or flue gases and a combined cycle gas turbine unit (CCGT) with a recovery boiler, which simultaneously produce electricity, heat and cold for centralized and decentralized supply of consumers, are presented. In addition, the production of liquid and gaseous carbon dioxide is possible. The main elements of the plants are a heating unit, a gas turbine unit with a recovery boiler, a turboexpander unit and a carbon dioxide unit for the production of cold, liquid and gaseous carbon dioxide. A thermodynamic calculation and a brief exergy analysis of the plants were carried out.

SO $_2$ is a major constituent in air pollution. Pet coke (having 6% Sulphur) with lime stone are being used for power generation in thermal power plants. Sulphur dioxide is produced during combustion of fuels containing sulphur and affects the environment in number of ways like acid rain corrosion and severe damage to health. Flue gas desulphurization (FGD) is the technique used for removal of SO $_2$ from exhaust flue gases in power plants. In accordance with the invention, flue gases containing sulphur dioxide are passed through a solution which was rich with sodium ions to produce sulphate by using SO $_2$ monitoring kit of SO $_2$ measurement. To find the optimum temperature of absorption of SO $_2$ in NaOH solution, the study was carried out at various temperatures. As is clear from Table 2 it is 20–25°C which is the most appropriate for the maximum absorption of SO $_2$ by NaOH solution. Similar sets of experiments were carried out by varying the time intervals for absorption of SO $_2$ by NaOH solution. As is shown in Table 4 the increased absorption of SO $_2$ is observed with increase in time intervals.

We propose a new cycle air preparation unit which helps increasing energy power of gas turbine units (GTU) operating as a part of combined cycle gas turbine (CCGT) units of thermal power stations and energy and water supply systems of industrial enterprises as well as reducing power loss of gas turbine engines of process blowers resulting from variable ambient air temperatures. Installation of GTU power stabilizer at CCGT unit with electric and thermal power of 192 and 163 MW, respectively, has resulted in reduction of produced electrical energy production costs by 2.4% and thermal energy production costs by 1.6% while capital expenditures after installation of this equipment increased insignificantly.

Experimental study of water recovery from flue gas using hollow micro–nano porous ceramic composite membranes

Multifunctional backup electricity supply for NPP auxiliary needs based on combined-cycle power plant with hydrogen overheating