Volume 4, No. 11 (2005)
Articles
VIRTUAL INSTRUMENTATION FOR ENVIRONMENT PROCESSES MONITORING WITH APPLICATION IN GREENHOUSE CLIMATE
DUMITRAŞCU ALEXANDRU
The actual climate in the world has an important impact in the entire agriculture field, especially in the sector of the culture of plants. This reason together with the global heating are determine the people to choose the greenhouse solution and, also, their specific applications. Therefore, in the last time are developed a lot of applications for monitoring and control the greenhouse climate. This paper propose some simple applications: an application which simulates the control of the temperature and humidity of the greenhouse climate using fuzzy rules, an application which simulates the acquisition of the temperature and humidity values from sensors and the control of these values to be between an acceptable limits, and third is an application which simulate the filling of a water tank having a level reference. These applications are very simple developed into the LabVIEW environment that offers the user a good graphical interface easy to use and understanding.
PROBLEMS ASSOCIATED WITH BIOMASS COMBUSTION IN INDUSTRIAL BOILERS
ION V. ION
This paper describes the technologies of biomass combustion and the associated problems. Biomass is plant matter such as trees, grasses, agricultural crops, residues from agriculture or forestry, and the organic component of municipal and industrial wastes. It can be used as a solid fuel, or converted into liquid or gaseous forms, for the production of electric power, heat, chemicals, or fuels. There are multiple techniques for the utilization of biomass for energy production, but today the dominant is biomass combustion. The key biomass combustion issues are efficiency, environmental performance and undesirable reactions in combustor and boiler such as ash fouling and slagging, which reduce the heat transfer and produce corrosion and erosion of boiler surfaces. These problems are caused by the presence of the inorganic material in fuel (metals, silica, sulfur and chlorine).
SOME PROBLEMS ABOUT ENVIRONMENT PROTECTION AT THE ENERGETICALLY GROUNDS C.E. ROVINARI AND C.E. TURCENI
ORBAN MARIA DANIELA, POPESCU CRISTINEL, ANCUTESCU IOSIF
The power plants are main pollution generation due to their technological processes, the nature of processed raw materials, the waste generated, the number of installations and the size of the affected landmass.
MEASURES TO PREVENTION OF THE POLLUTION RISK FOR THE SOIL AND BIODIVERSITY AROUND THE ASH AND SLUDGE DEPOSITS
PETCU ANDREIA, PETCU HORIA-IONUŢ
They are many different pressures for the soil and biodiversity because of different pollutants generated by ash and sludge deposits. In this paper we debate the legal approach of soils and biodiversity management and the methods for prevention and reduction the pollution effects.Ash and sludge deposits have large area for each thermal power plant with carbon fuel. In this paper will be show the compositions of the ash and sludge by the principals deposits and the effects of different pollutants to the soil and biodiversity and the prevention methods basis to the ecotoxicology integrated approach.
DETERMINING THE PARAMETERS OF ENTRAINMENT OF DROPS IN ELECTRIC FIELD DURING BUBBLING AND BOILING OF LIQUIDS IN ENERGETICAL INSTALLATIONS
PUIU-BERIZINŢIU MIHAI, SAJIN TUDOR, CRĂCIUN ALEXANDRU, BUZDUGĂ ŞTEFANIA ROXANA
A method is proposed for investigating the parameters of entrainment of drops due to their inertial path, ponderomotive forces of the electric field, and viscous friction of the phases. The concept entrainment coefficient characterizing the portion of drops being transported is introduced. It is shown that the use of the electric field is most advisable for an experimental determination of the parameters of entrainment. Processing of experimental data on electro convective entrainment of drops from the surface of a bubbling layer of distilled water was carried out by the proposed method.
THE AIR POLLUTION PRODUCED BY THE ENERGY SOURCES IN THE CITY AREA OF ORADEA
VASIU IOAN, SZASZ-BUTIRI ELENA
The work presents the level of the main pollutant emissions registered in the Oradea area, produced mainly by The Cogeneration Thermal Plant, running on pulverised low-grade coal and natural gas.The analysis emphasises the exceed of the allowed limits of the concentration of ash powder and SO2 emissions from the flue gases exhausted in the environment. The diminishing of the consumed fossil fuels by the improvement of the efficiency of energetic steam boilers, represents an important method of reducing the pollutant emissions.
ENERGY STORAGE USING SUPERCAPACITORS
LUNGOCI CARMEN, HELEREA ELENA
In the storage process of electric energy, the supercapacitors represent a viable alternative in energy supplying and recovering energy. The paper presents the supercapacitor general technical description, the principle of operation, and their charged and discharged processing.It is also describes the equivalents schemas for supercapacitors, with an example of two connections, serial and parallel. Among the many applications of supercapacitors there is a classical energy alimentation systems.
SISTEM DE MONITORIZARE, COMANDÃ ªI CONTROL LA UN BARAJ HIDROENERGETIC
VASILE LILIANA, CIOBANU CONSTANTIN, CHELU CRISTIAN
Reabilitarea din motive de siguranþã are caracter prioritar ºi se impune în toate situaþiile în care starea unor instalaþii componente ar putea conduce la avarii grave, având drept consecinþã pagube umane ºi materiale proprii sau la terþi. Este mai ales cazul barajelor ºi a echipamentelor acestora.Necesitatea reabilitãrii prin realizarea unui sistem de supraveghere, urmãrire ºi control al unui baraj devine iminentã în situaþia în care starea echipamentelor unei amenajãri hidroelectrice conduce la o indisponibilitate majorã de timp sau de capacitate de producþie, prin urmare la pierderi financiare însemnate, având ca scop atât eliminarea riscului unei avarii iminente atât pentru populaþie cât ºi pentru mediu, precum ºi prelungirea duratei de viaþã a obiectivului prin reconstituirea sau îmbunãtãþirea performanþelor iniþiale din proiect.Baraj hidroenergetic, apã, debite deversate, retehnologizare, control , siguranþã
THE EXERGETIC EVALUATION FOR THE STEAM GENERATOR IN THE THERMO-ELECTRIC PLANT
DRĂGAN MARCEL, STRATULAT ELENA
This work presents the exergetic method of thermodynamic analysis applied generating steam in power plants. Using the result of the exergetic method, we emphasize the factors that reduce the fuel-steam conversion capacity.
ELECTRICAL LOSSES IN TWO WINDINGS TRANSFORMERS UNDER UNBALANCED LOADING
PORUMB RADU *, GOLOVANOV NICOLAE *, POSTOLACHE PETRU *, TOADER CORNEL *, LICHIARDOPOL VIRGIL **, RUSU ADRIAN
An original algorithm for the determination of electric energy losses in two-winding transformers from power transformer substations (TS) or transformer posts (TP) is developed in this paper.An adequate mathematical model for the general case of several transformer units (identical or different regarding the rated characteristics) within the same TS/TP is presented, under the assumption of unbalanced and non-symmetrical loading due to customers demand.The optimal energy losses, when symmetrical and balanced loading is assumed, are emphasized, and the authors discuss the factors (in the form of load diagram fill-up coefficient, load diagram shape coefficient, etc.) that may affect them, given the variety and heterogeneous character of customers aggregation supplied from TS/TP.
SYNCHRONOUS VS. ASYNCHRONOUS STATE
GALAN NECULAI *, NICOARA BOGDAN *, MAMEDOV ARIF **, DIACONU CIPRIAN ***
The principle of the starting characteristics computation (torque, slip and current) is to consider the starting process as a sequence of successive steady states of constant slip; this is possible because the electric circuit time constants are small compared to the mechanical time constant. Based on the mathematical model of the electric circuits voltage equations and of the movement equation the absorbed current, the startup time and the heating during the startup process are studied. The paper includes the following important contributions: the expression of the electromagnetic torque produced by the field winding connected to a series resistance ra, the resistance ra optimization based on minimum startup time criterion, elaboration of a simple relation for the temperature rise during the first start and then for subsequent restarts.
LARGE POWER TRANSFORMER TRANSIENTS
POPESCU EUGEN *, RUSU ADRIAN *, NICOARA BOGDAN *, LICHIARDOPOL VIRGIL **
The paper deals with the transient behavior of large power transformers when switched in parallel. A practical situation from an electric substation is considered where two large power transformers, with non-linear magnetizing characteristic are switched in parallel. All the equipment in the substation are modeled with their corresponding transient equivalent diagram. The electric diagram contains: the equivalent voltage source at the far end of the 400 kV transmission line, other transmission lines connected at the same 400 kV bus bar, the 400 kV bus bar, two 250 MVA power transformers, the 110 kV bus bars, power transformers on the 110 kV side, 110 kV distribution lines, the compensation reactor, switches, disconnectors, voltage and current transformers.Further, different transients are computed and analyzed with special reference to the voltages and current on both sides of the transformers. It was found that the in-rush currents show a significant zero sequence component, which explains the actual behavior of the zero sequence relays