SPECIALIZED COMPUTING SOFTWARE FOR THE ASSESSMENT OF ENERGY EFFICIENCY AT THE LEVEL OF A STEAM BOILER

Transcription

1 Proceedings of 2017 Internationa Conference on Hydrauics and Pneumatics - HERVEX November 8-10, Băie Govora, Romania SPECIALIZED COMPUTING SOFTWARE FOR THE ASSESSMENT OF ENERGY EFFICIENCY AT THE LEVEL OF A STEAM BOILER Siviu ANDREESCU 1, Caudiu-Ione NICOLA 1, Marce NICOLA 1, Sebastian POPESCU 1, Viorica VOICU 1, Marian DUȚĂ 1 1 Nationa Institute for Research, Deveopment and Testing in Eectrica Engineering ICMET Craiova andreescu11@yahoo.com, nicoacaudiu@icmet.ro, marce_nicoa@yahoo.com, tn.spopescu@icmet.ro, programe@icmet.ro, marianduta@icmet.ro Abstract: The assessment of energy efficiency at the eve of a steam boier, inside which an organized activity is carried out is a compex process whose outcome typicay has a synthetic character. The performance indicators, either energy efficiency, or specific consumption, etc. were determined based on an agorithm for unit cacuation, thus creating a consistent database for fast eaboration of optima thermoenergetic audits, considering the measured and the determined therma parameters. These cacuation agorithms, specific to baance equations are incuded in the speciaized computing software proposed for the anaysis and processing of therma quantities. The eaboration of such a speciaized computing software for the anaysis and processing of therma quantities which are part of baance equations, for major industria consumers commony met in the practice of thermo-energetic audits, namey steam boiers, eads to the optimization of the activity from the point of view of therma energy. Keywords: Thermo-energetic baance, thermo-energetic parameters, computing software, LabVIEW 1. Introduction Energy resources represent an important part of materia resources, the feedback of deveoped countries and others being materiaized with reference to these resources through the deveopment of the concepts of aternative energy, renewabe energy, energy management and energy efficiency. Together, energy efficiency and protection of the environment constitute one of the major strategic objectives undertaken by the European Commission in the first European Energy Charter, signed at the Hague in The genera directions for action recommended in the most recent documents incude energy conservation, energy management, and the furtherance of new and renewabe sources of energy. One of the most frequent thermo-energetic consumers on the market of energy audits is the steam boier [1]. The assessment of energy efficiency at the eve of a steam boier, inside which an organized activity is carried out is a compex process whose outcome typicay has a synthetic character. Energy efficiency and inefficiency respectivey cannot be measured directy, they can be expressed based on one or more energy efficiency indicators, whose vaues determined on the basis of the monitoring resuts are compared with a reference vaue. The performance indicators, either energy efficiency, or specific consumption, etc. were determined based on an agorithm for unit cacuation, thus creating a consistent database for fast eaboration of optima thermo-energetic audits, considering the measured and the determined therma parameters. These cacuation agorithms, specific to baance equations are incuded in the speciaized computing software proposed for the anaysis and processing of therma quantities. The eaboration of this computing software eads to the speed-up of the stages of impementation of a thermo-energetic baance, with a possibiity to perform severa combinations between the therma parameters which concur for the achievement of an optima baance. The eaboration of such a speciaized computing software for the anaysis and processing of therma quantities which are part of baance equations, for major industria consumers commony met in the practice of thermo-energetic audits, namey steam boiers, eads to the optimization of the activity from the point of view of therma energy. The use of speciaized computing software aows the thermo-energetic audit and baance activities 308

2 Proceedings of 2017 Internationa Conference on Hydrauics and Pneumatics - HERVEX November 8-10, Băie Govora, Romania to be improved in the fied of generation and quaity of therma energy, in accordance with the requirements of the current European standards, the rues in force and the energy requirements approved by ANRE (Reguatory Authority for Energy). Due to the mutitude of thermo-energetic parameters required for the baance equations, such speciaized programs were not deveoped unti now, except for preparing eectrica energy baance sheets [2]. 2. The cacuation agorithm Consider the Bock-Steam type boier fueed by heating oi, a fue with ow heating vaue H I [kj/kg] and utimate composition C [%]; H [%]; S [%]; O [%]; W [%]. A BA type boier is a boier with a fire tube and three burnt gases tubes [3, 4]. The main functiona parameters, according to the instruction book are the foowing: Nomina output; Nomina pressure; Steam temperature: according to the saturation pressure; Suppy water temperature; Chimney gas temperature: [ºC]; Fue consumption: [kg/h]; Efficiency: [%]. The contour of the baance incudes the physica imits of the boier. The thermo-energetic baance sheet was deveoped for the time unit [5]. The equation of the therma baance of the boier is: Qc,ch Qc, f Qa QL QW Qu Qga, f Qga,ch Qp Qrc[kW] (1) Q c,ch chemica heat of fue; Q c,f sensibe heat; Q a the sensibe heat of the suppy water and of the water injected in the steam governor; Q W - heat generated by the eectricity suppied to the contour; (to be measured) Q L sensibe heat of air (incuding infitrated air) fed into the boier; Q u absorbed heat consisting of the heat of the steam generated by the boier and the heat yieded to the steam reheater; Q ga,f heat oss from sensibe heat of burnt gases, incuding the heat oss from the injection steam of iquid fues; Q ga,ch heat oss from incompete chemica combustion; Q p heat oss from purge water; Q rc heat oss to the environment due to the heating of the outer surfaces. B is the fue consumption, in kg/s; H i the ow heating vaue of the fue, in kj/kg. c pc is the specific heat of the fue, in kj/(kg ºC); t c fue temperature, in ºC. for fue density ρ 0,9 kg/dm 3, Qc,ch BHi [kw] (2) Qc, f Bc pctc [kw] (3) c o pc 3849, 2, 34 2, 299* 10 3 tc [ kj /( kg C )] (4) 309

3 Proceedings of 2017 Internationa Conference on Hydrauics and Pneumatics - HERVEX November 8-10, Băie Govora, Romania or tabuar choice depending on the density and temperature of the fue. Qa D a i a [ kw] (5) D a the suppy water fow rate, in kg/s; i a the enthapy of the suppy water, corresponding to the suppy water temperature, t a - suppy water temperature in kj/kg. QL 0 ev BVa il [ kw ] (6) α ev the excess air equivaent coefficient measured with burnt gases evacuation; V 0 a theoretica air voume necessary for iquid fue unit combustion, in m 3 N/kg; i L enthapy of combustion air, in kj/m 3 N at the baance contour inet temperature, t L, i L= c L t L or choose from the tabes. or it can be chosen from the iterature. 1 O 0, C, H Va , 33[ m 3 N / kg] (7), ev (8) O 0, 5CO N N2 0, 429 RO CO K 2 V 0 a the theoretica air voume necessary for iquid fue unit combustion can aso be chosen from the iterature depending on the ingredients of the iquid fue. α ev the excess air equivaent coefficient measured with burnt gases evacuation may aso be chosen from charts, depending on the oxygen, nitrogen, carbon monoxide and triatomic gases (RO 2 =CO 2 +SO 2 ) percent in the composition of burnt gasses evacuated through the chimney, in%, and depending on the gravimetric percentage components of carbon, suphur, hydrogen, and water in the fue used (or it can be chosen from charts) O 2, N 2, CO, RO 2 represent the oxygen, nitrogen, carbon monoxide and triatomic gases (RO 2 =CO 2 +SO 2 ) percent in the composition of burnt gasses evacuated through the chimney, in %, whie: K C 0, 375S (9) Qu D ab i ab [ kw] (10) D ab is the steam production of the boier, in kg/s; i ab steam enthapy, determined according to the saturation pressure, p ab, in kj/kg. C S 9H W 100 dinj Q gaf 0, 32 0, , C0t ga (11) 0, 536 RO2 CO

4 Proceedings of 2017 Internationa Conference on Hydrauics and Pneumatics - HERVEX November 8-10, Băie Govora, Romania C, S, H, W are the gravimetric percentage components of carbon, suphur, hydrogen, and water in the fue used; RO 2 =CO 2 +SO 2 are triatomic compounds in burnt gases; CO the content of carbon monoxide (RO 2 and CO 2 are percent by voume in terms of dry burnt gases); t ga temperature of burnt gases at the outet of the baance contour, in ºC; d inj the fow density of steam required for the injection of the iquid fue mass unit. C fow rate of the fue fed to the furnace, in kg/s; Q m heat oss through incompete combustion. Ceary, for the iquid and gas fues C=C 0. or: Qm C0 C 1 [ kg / s ] (12) 100 Q ga, f = Dgacgat ga (13) where D ga, c ga, t ga, refer to the fow rate, specific heat and temperature of burnt gases at the outet from the boier. C Qga,ch 12680CO C0 [ kw ] (14) 0, 536CO2 CO100 or Q ga,ch =D ga H ico CO; D ga fow of burnt gases evacuated from the boier; D ga =BV ga ; B fue consumption; V ga voume of burnt gases evacuated from the boier; V 0 ( 1)V 0 ga =Vga ev a (15) V 0 ga theoretica voume of burnt gases resuting from combustion of 1 m 3 of fue with the necessary theoretica air (α ev =1); V 0 a the theoretica air voume necessary for the combustion of 1 m 3 of fue; H ico ow heating vaue of carbon monoxide. Qrc [ kw] q5 Qc Qinj QL (16) where q 5 is chosen from specia charts and represents the percentage oss to the environment in reation to the heat fed to the furnace, or, in the case of recovery boiers, hot gas heat. D p the purging fow rate, in kg/s; i p enthapy of purge water, i p =i (p ab ), in kj/kg. 3. Speciaized computing software Qp Dpip [ kw] (17) In the graphica programming environment provided by LabVIEW, the virtua instrument defines a software modue, a program consisting of a user interface, front pane (simuating intuitivey the 311

5 Proceedings of 2017 Internationa Conference on Hydrauics and Pneumatics - HERVEX November 8-10, Băie Govora, Romania front side of the cassic instrument) and a bock diagram type program (a diagram, accessibe ony to the programmer) [6]. The front pane is the user-wise interface of the virtua instrument and the key eement of programmes deveoped in LabVIEW because the data input or extraction to/from the programming environment is achieved by means of this front pane. On the front pane, the contros requiring user interaction are heaviy simpified, with emphasis on graphic dispay and contro eements, known as contros or indicators. The contros represent inputs to the virtua instrument, performing data inputs, whie the outputs, which communicate the data resuting from the process to the operator are known as indicators (dispay eements). The contros have different forms, such as key buttons, switches, siders, dias, etc., each type matching an eement from the cassica instrument [7]. LabVIEW can be used to dea with data structures from simpe to very compex, numeric vaues, text strings, graphs, etc. In the case of indicators, these data structures managed by the program determine their own optima shape for presenting the data they receive. Data inputs and outputs are dua, intended for both the operator and the programme, and the distinction between contros and indicators is not rigid, athough some are excusivey dispay eements, and others are contro eements [8]. The bock diagram accompanies the front pane and can be conceived as a source code, as it is known in cassic programming anguages. Its components represent the nodes of the programme such as ogica structures, mathematica operators, ogica processing functions, etc. The connection of components is achieved through wires defining the fow of data within the virtua instrument created by the program [9]. The bock diagram is actuay a chart used by the programmer to describe the agorithm required for the appication to perform the necessary computing and reasoning for data retrieva and processing. In most cases, after the programmer has deveoped an appication and deivered it to a user, the atter no onger has access to the chart, the same way users of other programs do not have access to their source code [10]. The software interfaces of the computing software appication is shown in figure 1, 2 and 3. Fig. 1. Software interface of the cacuation for input into contour 312

6 Proceedings of 2017 Internationa Conference on Hydrauics and Pneumatics - HERVEX November 8-10, Băie Govora, Romania Fig. 2. Software interface of the cacuation for output from the contour Fig. 3. Software interface of the cacuation of the therma baance equation Athough LabVIEW anguage consists of a the required eements for writing programs, there is aso the possibiity of writing source ines in C anguage, via a specia Formua Node node structure. Another specia structure, the MathScript Node aows inputting ines of code simiar to MATLAB program. This consideraby expands the programming possibiities, enabing the users to write their own code sequences and extending the standard faciities provided by the LabVIEW environment. So we can say that this is an open environment, which increases its performance [11]. 313

7 Proceedings of 2017 Internationa Conference on Hydrauics and Pneumatics - HERVEX November 8-10, Băie Govora, Romania Fig. 4. Bock diagram of the speciaized computing software The computing software appication aso automaticay generates reports to Exce fies, and the bock diagram of the software process is shown in Figure 5: Fig. 5. Generation of Exce type report 314

8 Proceedings of 2017 Internationa Conference on Hydrauics and Pneumatics - HERVEX November 8-10, Băie Govora, Romania 4. Exampe of cacuation The thermo-energetic baance aims to measure the energy quantities input to the contour during the anayzed time span, to determine the energy osses inside the contour and the quantities of usefu energy as the difference of two vaues. Tabe 1: The average vaues of the measurands for a boier Measurand Symbo Unit Vaue Fue consumption B m 3 /h 36 Low heating vaue of the fue H i kj/m Fue temperature t C C 20 Temperature of the air inet in the furnace t L C 20 Suppy water fow rate D a kg/h 500 Suppy water temperature t a C 100 Steam production D ab kg/h 425 Steam pressure p ab bar 25 Steam temperature t ab C 200 Burnt gases temperature t ga C 110 Starting with the vaues shown in Tabe 1, foowing the appication software run, the resuts obtained in the figures 6, 7, and 8. Fig. 6. Software interface of the cacuation for input into contour for the steam boier 315

9 Proceedings of 2017 Internationa Conference on Hydrauics and Pneumatics - HERVEX November 8-10, Băie Govora, Romania Fig. 7. Software interface of the cacuation for output from the contour for the steam boier Fig. 8. Software interface of the cacuation of the therma baance equation for the steam boier 5. Concusions The eaboration under a uniform conception of the documentation reating to the agorithms for cacuating the therma parameters associated with steam boiers has promoted the deveopment of software for these types of instaations for the production of heat, currenty required in the practice of thermo-energetic audits and baances. The cacuation agorithms, specific to baance equations, can be found in a speciaized computing program for the anaysis and processing of therma quantities. The anaytic expressions for cacuating the therma parameters specific to heat consumers can be found in the LabVIEW graphica programming environment, a programming system which has revoutionized the deveopment of test, measurement and contro appications. By mean of this 316

10 Proceedings of 2017 Internationa Conference on Hydrauics and Pneumatics - HERVEX November 8-10, Băie Govora, Romania system, an interface can quicky and efficienty be achieved with the hardware for data acquisition and contro, data anaysis can be performed, and usefu systems can be designed for deveoping optimized baances. The parameterized software creates the prerequisites for improving such thermo-energetic audit and baance activities by data management, performance of measurements and anaysis, interpretation of phenomena, situations in the fied of generation and quaity of therma energy, in accordance with the requirements of the current European standards, the rues in force and the energy requirements approved by ANRE. The speciaized computing software eads to the speed-up of the stages of impementation of a thermo-energetic baance, with a possibiity to perform severa combinations between the therma parameters which concur for the achievement of an optima baance. Acknowedgments The paper was deveoped with funds from the Ministry of Education and Scientific Research as part of the NUCLEU Program: PN References [1] A. Badea, M. Stan, R. Patrascu, Bazee termoenergeticii, Bucuresti, 2003; [2] ANRE Ghid de eaborare a auditurior energetice. Decizia 2123/ ; [3] V. Iiescu Grozavesti, Cartea fochistuui, Editura tehnica, Bucuresti-1962; [4] M. C. Dianu, Aparate termice.cazane, Bucureşti, 2009; [5] C. Raducanu, R. Patrascu, Bianturi termoenergetice, Bucuresti, 2004; [6] Introduction to LabVIEW, [Onine]. Avaiabe: to%20labview.pdf; [7] LabVIEW TM - Getting Started with LabVIEW, [Onine]. Avaiabe: [8] LabVIEW User Manua, onine: [9] J. Jovitha. (2010, January 30). "Virtua Instrumentation Using Labview", [Onine]. Avaiabe: [10] H. P. Havorsen. (2014, Mar. 07). Introduction to LabVIEW. [Onine]. Avaiabe: to%20labview.pdf; [11] LabVIEW MathScript RT Modue [Onine]. Avaiabe: 317