Dynamic monitoring and evaluation on the flue gas emission of waste. incineration

Size: px
Start display at page:

Download "Dynamic monitoring and evaluation on the flue gas emission of waste. incineration"

Transcription

1 Dynamic monitoring and evaluation on te flue gas emission of waste incineration Jianli Cao 1,Wei Pan 1, College of Science, Henan University of Tecnology, Zengzou, Henan, Abstract: Troug Gauss diffusion model, te flue gas emission of waste incineration is studied. A dynamic monitoring system is establised naturally. Ten te quality coefficients of contaminants are calculated, and te destructiveness of pollutants is evaluated by te grey compreensive evaluation metod. Keywords: Gauss diffusion model; quality coefficients; te grey compreensive evaluation metod I. INTRODUCTION Nowadays, junk besieged city as become a worldwide problem, so ow to andle te garbage as become a torny problem. Garbage incineration makes people find a solution to te"garbage siege". However, te pollution of tras incinerator is also wort pondering. At te beginning of te 1st century, Dioin around tras incinerator was studied in AERMOD model by Trin [1. Te movement of polluted gas is inverstigated troug computer simulation by Wan Fan et al [. In tis paper, te movement and effect of gases from tras incinerator in Senzen are analysised and evaluated by virtue of Gauss diffusion model and te grey compreensive evaluation metod. II. THE DYNAMIC MONITORING OF FLUE GAS EMISSION OF WASTE INCINERATION.1 Te solution of te effective eigt of te gas diffusion Te effective eigt of te gas diffusion H e includes two parts: Geometric eigt of cimney H and te lifting eigt of te flue gas to te surface H (as sown in figure 1). Fig.1 Scematic diagram of flue gas emission eigt Te lifting eigt of te flue gas refers to te flue gas in te cimney mout after eclusion of momentum and eat under te action of buoyancy to continue rising eigt, so we can get H e H H (1) DOI: /IJRTER LAUY 35

2 To deeply study te lifting eigt of te flue gas, tere are some cases to consider. Case one. Consider te situation wit windy and unstable conditions. A. If te eat release rate of flue gas Q 1000 kj / s, and te temperature difference between flue gas and environment T 35K, we use te following formula to calculate H, n 1 1 n H nq 0 H u T Q 0.35P Q T a v s () (3) were n0 is te coefficient of flue gas eat condition and surface conditions, n1 is te inde of flue gas eat release rate, n is te inde of eaust tube eigt, Q is te flue gas eat release rate, T is te temperature difference between flue gas outlet and environment, Ts is te temperature of flue gas outlet, Qv is te actual eaust rate, Pa is atmosperic pressure, and n0, n1, n is as sown in te following table 1. Table1. Te value of n 0, n 1, n Q /( kj / s ) Surface conditions Q 1000 kj / s City and suburban area /3 / kj / s Q 100 kj / s, T 35K City and suburban area 0.9 3/5 /5 B. If 100 kj / s Q 1700 kj / s, ten n 0 n 1 n H H ( H H ) 1 Q H (1.5 V D0.01 Q )/ u 0.048( Q 1700)/ u s (4) (5) C. If Q 1700 kj / s or T 35K, ten H (1.5 V D 0.01 Q )/ u s (6) Case two. Consider te situation wit windy and stable conditions, ten we ave 1/3 dta 1/3 H Q ( ) u dz 1/3 (7) Case tree. Consider te situation wit static wind ( 0.5 m/ s u m/ s ) or breeze ( u m/ s), ten we All Rigts Reserved 36

3 dt 5.50 ( a H Q ) dz 1/4 3/8 (8). Te basic diffusion model of atmosperic environment monitoring Te basic model of atmosperic environment quality is derived from te teory of turbulent diffusion. Tis sows tat diffusion of pollutants in te atmospere is tree dimensional. Tus te basic equation for te pollutants concentration C is a tree-dimensional model [3. C C C C C C C b Ec, E c, y E c, z f g KC ep( ai ) t y z y z (9) In order to estimate parameters more accurately, we discussed different situations. Situation one. If only considering te impact of te wind (te oter conditions are same), te flue gas emissions is mainly due to te runoff from pollution cimney, wic makes te wind speed and direction in te emission te biggest factors of flue gas. Conseqently, te wind speed and direction may cange te flue gas concentration in a certain area. Let S be te wind vector in different conditions, ten te flow velocities u, v, w in, y, z aes are as follows [4. u f (, y, z, s) v g(, y, z, s) w (, y, z, s) Substituting into te equation (9), we obtain c c c c c c c E E y E z kc f g t y z y z. (10) were f, g, epress in different forms, tus te analytical solution of concentration distribution of eavy metals is different. Comparing te pollutants concentration distribution in space wit te observation values, we may use te polynomial approimation functions of f, g, to determine te approimate impact on te pollutants concentration. If te wind speed is in te direction of ais, ten te spatial distribution trend figure of pollutant concentration obtained from simulation model is as sown in All Rigts Reserved 37

4 Fig. Te diffusion in te direction of ais Situation two. If considering te impact of rainfall and temperature, ten we make te correction for te flue gas concentration since rainfall as a dilution effect for te flue gas diffusion [5. C( ) C.ep( ) b ai were is rainfall intensity, a and b are constants, usually we take a as, b as 0.5. Ten combined wit te formula (9), we can get te flue gas in te diffusion equation under te influence of rainfall. I C C C C C C C b Ec, E c, y E c, z f g KC ep( ai ) t y z y z.3 Evaluation standard of gas concentration In order to envaluate if te gas concentration eceeds te critical value, it is nessesary to measure te maimum gas concentration on te ground and some monitoring points. Because te diffusion of gas takes time, by considering its delay time, te monitoring model is set up. (11) (1) (13) ( ) c( t) c( t ) S u (14) (15) were S is te orizontal distance from a certain monitoring point to te gas cimney. average speed of wind at te eaust tube outlet. After te data of 1 n measured, te epectation and variance model is establised as u is te Var( E( ( )) [ E( ( )) ) G All Rigts Reserved 38

5 Troug (16), we know te discarge of waste incineration plant is safe and stable wen G is sufficiently small. However, te situation is unsafe and instable wen G appears relatively large fluctuations. Consequently, te critical value of G becomes te standard value to evaluate te gas concentration. III. DYNAMIC MONITORING OF THE IMPACT ON SURROUNDING ENVIRONMENT 3.1 Stocastic simulation of gas diffusion in different places Since te monitoring points are limited, it is nessesary to make stocastic simulation of gas diffusion. We coose te nearest or te most convenient point in different directions on residential areas surrounding te waste incineration plant and collect te flue gas data in some locations (as sown in table ). Table Different locations of pollutant emissions data [6 coordinates were te ratio to te real distance is particles HCL SO NOX Hg Pb Dioin 1:00 (.1, 3.) ( 6.7,5.5 ) ( 13.5, 4.5) , r(, y) ( 5,.6 ) 3. Grey compreensive evaluation metod In order to evaluate te damage of differnet pollutants, te witening function model is establised [7. Te witening function for te j-t (j=1,, n) level of te i-t (i=1,, 7) pollutant is constructed as follows. Wen j=1, Wen j=,3, 6, ten Wen j=7, ten 1 0, s ) s f ( ) 1 [ s, si( 1) s si( 1) 0 [ si ( 1) s, ) f si( 1) 1 [ 0, si( 1) si( 1) 1 [ si( 1), s s 1 [ s, si ( 1) s s i( 1) 0 [ s s, ) f i( 1) s 0 [ si( 1), i( 1) 1 [0, si( 1) si( 1) (17) (18) All Rigts Reserved 39

6 By direct calculation, we get te witening function and correlation function (te grapics are sown as figure 3 and figure 4). Fig.3 Te first witening function Fig.4 Te sevent witening function To determine te weigt of tese 7 contaminants, te critical values are listed in table 3. Table 3. Te critical values of 7 contaminants SO NO X Particles HCL Hg Pb Dioin Ⅰ Ⅱ Ⅲ Ten te weigt wi of te i-t (i=1,, 7) contaminant can be calculated troug following formula w i 7 i1 si( 1) / s ( i 1,,, 7) ( s / s ) i( 1) (0) were s is te standard value of te j-t (j=1,, n) level for te i-t contaminant. Troug te formula (0), te relevant weigt results are sown in table 4. Table 4. Te weigt of 7 contaminants SO NOX Particles HCL Hg Pb Dioin Now we introduce te cluster parameter kj to reveal te close degree of te evaluation object and te relevant level of contaminant kj 7 i1 w i f ( ki ), j=1,, n, k=1,, m. At last, we use te quality coefficient k to evaluate te destructiveness of All Rigts Reserved 40

7 7 k i i i1 w f () (1) were f ( ) i 1, [0, s,( i 1,,,7) i( 1) si( 1) i( 1) 0, [ s,,( k 1,,, m) () Te data of quality coefficients and teir ranking in different positions are sown in table 5. Table 5. Quality coefficients and ranking in different positions Te evaluation objects Quality coefficient Quality ranking B(.1, 3.) C D( 6.7,5.5 ) E( 13.5, 4.5) ( 5,.6 ) From te above table 5, it is clear tat te bigger of quality coefficient, te better of te local environment quality, and te smaller of te influnce wit te gas diffusion. ACKNOWLEDGEMENT Tis work is supported by te National Foundation of Cina (Grant No. 14BGL153) and Basic Researc Fund under Grant No. 014GJYJ-B30 and [01-JKGHAB-007. REFERENCES I. Trin H. Validation of te AERMOD air dispersion model: application to congener specific dioin deposition from II. III. IV. anincinerator in midland, Micigan[J. Organoalogen Compounds, 009,71: Wan Fan, Ma Xinqiang. Computer simulation of azardous gas diffusion in urban enviroments. [J.Guizou Science.007,5():4-33 San J R, Perez J L, Gonzalez R M. An incinerator air quality impact assessment for metals, PAH, dioins and furans by using te MM5-CMAQ-EMIMO atmosperic modeling system: Spain case study [J. International Journal of Environment and Pollution, 008, 3():50-69 Onofrio M, Spataro R, Botta S. Te role of a steel plantin nort-west Italy to te local air concentrations of PCDD/Fs [J.Cemospere, 011, 8(5): V. Cao M R, Hu C W, Cen Y L. Approacing gas particle partitioning equilibrium of atmosperic PCDD/Fs wit VI. VII. increasing distance from an incinerator: measurements and observations onmodeling [J. Atmosperic Environment, 004,38(10): [DB/CD.ttp:// Ding Jin bao, He Qing, Ceng Yongping. Evaluation of grey compreensive evaluation metod and te atmospere environment quality[j. Sicuan Environmental Journal, 1993, 13(): All Rigts Reserved 41