General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.

Users may download and print one copy of any publication from the public portal for the purpose of private study or research.

You may not further distribute the material or use it for any profit-making activity or commercial gain

You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Downloaded from orbit.dtu.dk on: Jun 22, 2021

Dynamisk modellering af forgasning i fixed koksbed

Gøbel, Benny

Publication date:1999

Document VersionPublisher's PDF, also known as Version of record

Link back to DTU Orbit

Citation (APA):Gøbel, B. (1999). Dynamisk modellering af forgasning i fixed koksbed.

https://orbit.dtu.dk/en/publications/69129312-7ce2-4186-9b5a-e64747975e3c

ET-PhD 99-04

Dynamisk modeller ing

af

forgasning i fixed koksbed

Benny Gøbel

Institut for EnergiteknikDanmarks Tekniske Universitet

BILAG

1

Appendiksoversigt:

Appendiks 1: Harboøre-model, Programudskrift med pyrolysemodel 1 3Appendiks 2: Harboøre-model, Programudskrift med pyrolysemodel 2 15Appendiks 3: Dynamic Modelli ng of the Two-stage Gasification Process 27Appendiks 4: Konvektion 35Appendiks 5: Stråling 41Appendiks 6: Analytisk løsning af water-gas shift ligningen 49Appendiks 7: Entalpi-bestemmelse på basis af Knacke 55Appendiks 8: Elementaranalyse af Standard Gasifier Fuel (SGF) 63Appendiks 9: Fugtprocent i fli s 67Appendiks 10: Tømning af koksbed efter uge 37 69Appendiks 11: Dynamisk model af koksbedden version 1 73Appendiks 12: Dynamisk model af koksbedden version 2 95Appendiks 13: Dynamisk model af koksbedden version 3 121Appendiks 14: Dynamisk model af koksbedden med inputmodel 153Appendiks 15: Stationær model af koksbedden med inputmodel 183

2

3

APPENDIKS 1

HARBOØRE-MODEL

PROGRAMUDSKRIFT MED PYROLYSEMODEL 1

4

$TITLE= Harboøre / DTU

(* Stationær model af Harboøre forgasseren (indfødt 278000 kJ/h) model, der finder massestrømmene af vanddamp og produktgas ud af reaktoren, massestrømmen af den tilsatte luft til topbrænderen samt temperaturen af forgasningsmidlet og et estimat for varmetabet *)

(* Pyrolysemodel på basis af Hald *)

BEGIN

(************************* ERKLÆRINGER ***************************)

PARAMETER

(* biomasse *)m_trae_fugt(312.5), (* massestroem af fugtig flis, [kg/h] *)fugtindhold(30), (* fugtindhold i flis, [%] *)OprC(0.66), (* ilt-indhold i trae i fht. C, [-] *)HprC(1.4515), (* brint-indhold i trae i fht. C, [-] *)

(* forgasningsmiddel *)m_vand_forg(59.4), (* massestroem af vand, [kg/h] *)V_luft_forg(222), (* Volumenstroem af toer luft, [Nm3/h] *)p_total(1.01325E5), (* totaltryk = 101325 Pa *)Rho_luft(1.293), (* massefylde af toer luft v. 0 grader C *)

(* luft til topbrænder *)m_luft_top(54.3),

(* Overhedning af forgasningsmidlet, fast temperatur *) (* Temp. af forgasningsmiddel efter overhed, [K] *) (* Sættes til 0, hvis der ikke ønskes overhedning *)T_overhed(340),

(* Temperaturer, K *)T_trae(298.15), (* Temperaturen af indfødt træ, [K] *)T_luft_top(298.15), (* Temperaturen af luft til topbrænder, [K] *)T_fordamp(373.15), (* Temperaturen ved fordampning af vand, [K] *)Tu(393), (* Temperaturen ud af reaktor, [K] *)T2(808), (* Temperaturen i pyrolyse-zone, [K] *)T3(1073), (* Temperaturen i forgasnings-zone, [K] *)T4(2200), (* Temperaturen i forbrændings-zone, [K] *)T_0(273.15), (* Temperatur ved normaltilstand, 0 C *)T_25(298.15), (* Temperatur ved standardtilstand, 25 C *)

(* gasserne (ideal gas) *)K_N2(0.768), (* andel af N2 i luft, massebasis *)R_H2O(461.4), (* Gaskonstanten for damp, J/(kg*K) *)c_ideal(44.62), (* antal mol pr Nm3 idealgas *)M_N2(28E-3), (* molvaegten af N2 *)M_CO(28E-3), (* molvaegten af CO *)M_H2(2E-3), (* molvaegten af H2 *)M_O2(32E-3), (* molvaegten af O2 *)M_CO2(44E-3), (* molvaegten af CO2 *)M_CH4(16E-3), (* molvaegten af CH4 *)M_H2O(18E-3), (* molvaegten af H2O *)

(* beregning af nedre braendvaerdi *)h0_CO(283.0), (* kJ/mol *)h0_H2(241.9), (* kJ/mol *)

5

h0_CH4(802.5), (* kJ/mol *)h0_tjaere(25), (* MJ/kg *)

(*** Energibalance og udregning af varmetab ***)

(* Nulpunktsentalpier, J/kg *)h0_trae(-5.280E6),h0_vand(-15.87E6),h0_damp(-13.42E6),h0_luft(0),

(* Varmefylder, J/(kg*K) *)cp_trae(2260),cp_vand(4200),cp_damp(2026),cp_luft(1051),

(*** Atombalance ***)M_C(12E-3), (* Kg/mol *)M_H(1E-3),M_O(16E-3),M_N(14E-3),

(*** Ekstern krakning ***)T_krak(1073); (* Kraknings-temperatur *)

VARIABLE (* brændsel *)m_trae_toer, (* massestroemmen af toert trae *)M_trae, (* molvægten af træ *)

(* forgasningsmiddel *)T_forg_ind, (* Temperaturen af forgasningsmidlet, K *)T_dugpunkt, (* Dugpunktstemp. af forgasningsmidlet, K *)m_luft_forg, (* massestroem af forgasnings luft, kg/h *)x, (* absolut fugtighed *)p_damp(2E4), (* damptrykket i den fugtige luft, Pa *)

M_tjaere, (* molvægten af tjære *)

(* stofbalance for forbrændings-zonen *)C_ind_burn, CO2_ud_burn,

(* stofbalancer for forgasnings-zonen *)CO2_ind_forg, H2O_ind_forg,C_ind_forg, C_ud_forg, H_ud_forg, O_ud_forg,

(* variable til at bestemme gas-ligevægten i forgasnings-zonen *)a1(0.01), Ka,est_CO, est_H2, est_CO2, est_H2O,

(* ligevaegtskonc. af CO, H2, CO2, H2O i forgasnings-zonen *)CO_forg(0:), H2_forg(0:), CO2_forg(0:), H2O_forg(0:),

(* gasproduktion i pyrolyse-zonen *)CO_pyro, CO2_pyro, CH4_pyro, H2_pyro, H2O_pyro, tjaere_pyro,

(* vanddamp tilført i tørrings-zonen *)H2O_toerring,

(* gassammensætning efter reaktoren *)CO_reaktor, H2_reaktor, H2O_reaktor, CO2_reaktor, CH4_reaktor, N2_reaktor,

6

(* gassammensætning efter topbrænder *)O2_top, N2_top, stoek_gas, stoek_tjaere, stoek_lige,CO2_top, H2O_top, CO_burn_top, H2_burn_top, CH4_burn_top, tjaere_burn_top,

(* endelig gassammensætning [mol] *)CO, H2, H2O, CO2, CH4, N2, tjaere, gasprod,

(* endelig gassammensætning [%] *)CO_pro, H2_pro, CO2_pro, H2O_pro, CH4_pro, N2_pro,

(* beregning af nedre braendvaerdi *)braend_gas, (* MJ/Nm3 *)braend_tjaere, (* MJ/Nm3 *)

(******************* KONTROL *******************)

(***************** MASSEBALANCER *****************)

(*** Total atombalance ***)

(* IND *)C_ind, H_ind, O_ind, N_ind, M_total_ind,

(* UD *)C_ud, H_ud, O_ud, N_ud,

(*** atombalance ned gennem reaktoren ***)C_ind1, H_ind1, O_ind1, C_ud1, H_ud1, O_ud1, (* tørring *)C_ind2, H_ind2, O_ind2, C_ud2, H_ud2, O_ud2, (* pyrolyse *)C_ind3, H_ind3, O_ind3, C_ud3, H_ud3, O_ud3, (* forgasning *)C_ind4, H_ind4, O_ind4, C_ud4, H_ud4, O_ud4, (* forbrænding *)

(***** ENERGIBALANCE OG UDREGNING AF VARMETAB *****)

(* samlede entalpier, ind, [J/h] *)H_trae, H_vand_trae, H_damp_forg, H_luft_forg, H_luft_top, Q_Total_ind,

(* samlede entalpier, ud, [J/h] *)H_N2, H_H2, H_CO, H_CH4, H_CO2, H_H2O, H_tjaere, Q_Total_ud, Q_tab,

(*** ENERGIBALANCE NED GENNEM REAKTOREN ***)

(*** tørring ***)H_trae_ud1,H_N2_ud1, H_H2_ud1, H_CO_ud1, H_CH4_ud1,H_CO2_ud1, H_H2O_ud1, H_tjaere_ud1, H_gas_ud1,

H_N2_ind1, H_H2_ind1, H_CO_ind1, H_CH4_ind1,H_CO2_ind1, H_H2O_ind1, H_tjaere_ind, H_gas_ind1,balance1,

(*** pyrolyse ***)H_koks_ud2,H_N2_ind2, H_H2_ind2, H_CO_ind2, H_CO2_ind2, H_H2O_ind2, H_gas_ind2,balance2,

(*** forgasning ***)H_koks_ud3,H_N2_ind3, H_CO2_ind3, H_H2O_ind3, H_gas_ind3,balance3,

(*** forbrænding ***)

7

H_gas_ind4,balance4,

(*** Ekstern krakning ***)Ka_krak,C_gas, O_gas, H_gas,a, b, c, D, (* variable til løsning af 2. grads-lign *)

(* ligevaegtskonc. af CO2, CO, H2, H2O efter krakning, hhv i mol og procent *)CO2_krak(0:), CO_krak(0:), H2_krak(0:),H2O_krak(0:),CO_krak_pro, H2_krak_pro, CO2_krak_pro, H2O_krak_pro, CH4_krak_pro, N2_krak_pro;

(************************ PROGRAMMET STARTER **************************)

(***** Blandet *****)

(* Molvægten af træ (pr. C) på basis af atomar sammensætning *)M_trae:=1*M_C+HprC*M_H+OprC*M_O;

(* Bestemmelse af massestrømme af tørt træ og forgasningsluft *)m_trae_toer:= m_trae_fugt*(100-fugtindhold)/100;m_luft_forg:= V_luft_forg*Rho_luft;

(***** Temperaturen af forgasningsmidlet bestemmes (før overhedning) *****)(***** Mættet vanddamps temperatur som funktion af trykket *****)x:=m_vand_forg/m_luft_forg;0:=0.62198*(p_damp/(p_total-p_damp))-x;T_dugpunkt:=37.58-(4042.9/(LOG(p_damp)-23.5771));

(* programmet benytter den højeste af de to temperaturer: T_dugpunkt eller T_overhed som værdi for T_forg_ind *)IF (T_dugpunkt > T_overhed) Then T_forg_ind:= T_dugpunktElse T_forg_ind:= T_overhed;

(***** Modellering af forgasningsreaktoren *****)

(*** FORBRÆNDINGS-ZONEN ***)(*** atombalance for forbrænding ***)(* C omdannes til CO2 ved støkiometrisk afbrænding med den tilsatte forgasningsluft *)

C_ind_burn:=0.5*2*0.21*V_luft_forg*c_ideal;CO2_ud_burn:=C_ind_burn;(*** Forbrænding slut ***)

(*** FORGASNINGS-ZONEN ***)(*** atombalance for forgasning ***)(* C omdannes til CO og H2 efter reaktion med CO2 fra afbrændingszonen og H2O fra den tilsatte forgasningsluft, noget af kulstoffet fortsætter ned i forbrændingszonen *)

CO2_ind_forg:=CO2_ud_burn;H2O_ind_forg:=m_vand_forg/M_H2O;

8

(* netto input af fast kulstof (ind-ud) *)(* kulstof, massebalance på basis af Hald *)C_ind_forg:=0.50546*m_trae_toer/M_trae - C_ind_burn;C_ud_forg:=C_ind_forg + CO2_ind_forg;H_ud_forg:=2*H2O_ind_forg;O_ud_forg:=2*CO2_ind_forg + H2O_ind_forg;

(*** Gasserne i ligevægt iflg. Water-gas shift reaktionen ***)

(* ligevægtskonstant, Ka(T) *)Ka:=(0.000001303*T3+0.000717)*T3-1.3006;

(* forskellige startgæt på gassammensætningen *)(* bemærk, at hvis O_ud_forg < C_ud_forg skal der dannes metan, hvilket modellen IKKE tager hensyn til *)

IF O_ud_forg < 2*C_ud_forg THEN BEGIN est_CO:=2*C_ud_forg - O_ud_forg; est_CO2:=O_ud_forg - C_ud_forg; est_H2O:=0; est_H2:=H_ud_forg/2 ENDELSE BEGIN est_CO2:=C_ud_forg/2; est_CO:=est_CO2; est_H2O:=O_ud_forg - 3*est_CO2; est_H2:=(H_ud_forg - 2*est_H2O)/2 END;

0 :=(est_H2O+a1)*(est_CO+a1) /((est_CO2-a1)*(est_H2-a1))-Ka;

CO_forg :=est_CO+a1;H2_forg :=est_H2-a1;CO2_forg :=est_CO2-a1;H2O_forg :=est_H2O+a1;(*** Forgasning slut ***)

(*** PYROLYSE-ZONEN ***)(* Efter Hald og Henriksen *)CO_pyro:= 0.06030*m_trae_toer/M_trae;CO2_pyro:= 0.08318*m_trae_toer/M_trae;CH4_pyro:= 0.10956*m_trae_toer/M_trae;H2_pyro:= 0.05291*m_trae_toer/M_trae;H2O_pyro:= 0.27261*m_trae_toer/M_trae;tjaere_pyro:= 0.24150*m_trae_toer/M_trae;(*** pyrolysen stopper ***)

(*** TØRRINGS-ZONEN ***)H2O_toerring:=m_trae_fugt*fugtindhold/100/M_H2O;(*** tørringen stopper ***)

(*** udregning af gassammensætning efter reaktor ***)CO_reaktor:=CO_forg+CO_pyro;H2_reaktor:=H2_forg+H2_pyro;H2O_reaktor:=H2O_forg+H2O_pyro+H2O_toerring;CO2_reaktor:=CO2_forg+CO2_pyro;CH4_reaktor:=CH4_pyro;

9

N2_reaktor:=2*0.79*V_luft_forg*c_ideal/2;

(*** støkiometrisk afbrænding i topbrænderen ***)O2_top:= (1-K_N2)*m_luft_top/M_O2;N2_top:= K_N2*m_luft_top/M_N2;stoek_gas:= 2*CH4_reaktor + (CO_reaktor + H2_reaktor)/2;stoek_tjaere:= 1.042225*tjaere_pyro;stoek_lige:= stoek_gas + stoek_tjaere;

(*** Herunder kommer 3 forskellige modeller for afbrænding i top- brænderen. Først en model, hvor bare gassen afbrændes støkiometrisk. Dernæst en model hvor kun tjæren afbrændes og endelig en model, hvor både gas og tjære afbrændes støkiometrisk ***) (* De to modeller der ikke benyttes, skal kommenteres ud *)

(*CO_burn_top:= O2_top/stoek_gas*CO_reaktor;H2_burn_top:= O2_top/stoek_gas*H2_reaktor;CH4_burn_top:= O2_top/stoek_gas*CH4_reaktor;tjaere_burn_top:=0;CO2_top:= CH4_burn_top + CO_burn_top;H2O_top:= 2*CH4_burn_top + H2_burn_top;*)

IF stoek_tjaere > O2_top THEN BEGIN CO_burn_top:= 0; H2_burn_top:= 0; CH4_burn_top:= 0; tjaere_burn_top:=O2_top/stoek_tjaere*tjaere_pyro; CO2_top:= 1*tjaere_burn_top; H2O_top:= 0.75*tjaere_burn_top ENDELSE BEGIN CO_burn_top:= (O2_top-stoek_tjaere)/stoek_gas*CO_reaktor; H2_burn_top:= (O2_top-stoek_tjaere)/stoek_gas*H2_reaktor; CH4_burn_top:= (O2_top-stoek_tjaere)/stoek_gas*CH4_reaktor; tjaere_burn_top:=tjaere_pyro; CO2_top:= (1*tjaere_pyro) + CH4_burn_top + CO_burn_top; H2O_top:= (0.75*tjaere_pyro) + 2*CH4_burn_top + H2_burn_top END;

(*CO_burn_top:= O2_top/stoek_lige*CO_reaktor;H2_burn_top:= O2_top/stoek_lige*H2_reaktor;CH4_burn_top:= O2_top/stoek_lige*CH4_reaktor;tjaere_burn_top:=O2_top/stoek_lige*tjaere_pyro;CO2_top:= 1*tjaere_burn_top + CH4_burn_top + CO_burn_top;H2O_top:= 0.75*tjaere_burn_top + 2*CH4_burn_top + H2_burn_top;*)

(*** udregning af gassammensætning efter topbrænder ***)CO:=CO_reaktor-CO_burn_top;H2:=H2_reaktor-H2_burn_top;H2O:=H2O_reaktor+H2O_top;CO2:=CO2_reaktor+CO2_top;CH4:=CH4_reaktor-CH4_burn_top;N2:=N2_reaktor+N2_top;tjaere:=tjaere_pyro-tjaere_burn_top;Gasprod:=(CO+H2+H2O+CO2+CH4+N2)/c_ideal;

(*** gassammensætning efter topbrænder i procent ***)

10

CO_pro:= CO/(CO+H2+H2O+CO2+CH4+N2)*100;H2_pro:= H2/(CO+H2+H2O+CO2+CH4+N2)*100;H2O_pro:= H2O/(CO+H2+H2O+CO2+CH4+N2)*100;CO2_pro:= CO2/(CO+H2+H2O+CO2+CH4+N2)*100;CH4_pro:= CH4/(CO+H2+H2O+CO2+CH4+N2)*100;N2_pro:= N2/(CO+H2+H2O+CO2+CH4+N2)*100;

(*** beregning af nedre braendvaerdi ***)braend_gas:=(CO_pro*h0_CO+H2_pro*h0_H2+CH4_pro*h0_CH4)/100*c_ideal/1000;M_tjaere:= (1*M_C+1.5*M_H+0.66555*M_O);braend_tjaere:=tjaere*M_tjaere/Gasprod*h0_tjaere;

(*************************** KONTROL ****************************)

(***** Atombalance for hele reaktoren *****)(* IND *)C_ind:=m_trae_toer/M_trae;

H_ind:=m_trae_toer/M_trae*HprC +2*m_trae_fugt*fugtindhold/100/M_H2O +2*m_vand_forg/M_H2O;O_ind:=m_trae_toer/M_trae*OprC +m_trae_fugt*fugtindhold/100/M_H2O +m_vand_forg/M_H2O +2*0.21*V_luft_forg*c_ideal +2*(1-K_N2)*m_luft_top/M_O2;

N_ind:=2*0.79*V_luft_forg*c_ideal +2*K_N2*m_luft_top/M_N2;

M_total_ind:=C_ind*M_C+H_ind*M_H +O_ind*M_O+N_ind*M_N;

(* UD *) (*** atombalance efter topbrænder ***)C_ud:=CO+CO2+CH4+tjaere;H_ud:=2*H2+2*H2O+4*CH4+1.5*tjaere;O_ud:=CO+2*CO2+H2O+0.66555*tjaere;N_ud:=2*N2;

(***** MASSEBALANCER NED GENNEM REAKTOREN *****)(* massebalance for fordampning *)C_ind1:=m_trae_toer/M_trae + (CO_pyro+CO2_pyro+CH4_pyro+tjaere_pyro) + (CO_forg+CO2_forg);C_ud1:= m_trae_toer/M_trae + CO+CO2+CH4+tjaere;

H_ind1:=m_trae_toer/M_trae*HprC + 2*m_trae_fugt*fugtindhold/100/M_H2O + (2*H2_pyro+2*H2O_pyro+4*CH4_pyro+1.5*tjaere_pyro) + (2*H2_forg+2*H2O_forg);H_ud1:= m_trae_toer/M_trae*HprC + (2*H2+2*H2O+4*CH4+1.5*tjaere);

O_ind1:=m_trae_toer/M_trae*OprC + m_trae_fugt*fugtindhold/100/M_H2O + (CO_pyro+H2O_pyro+2*CO2_pyro+0.66555*tjaere_pyro) + (CO_forg+H2O_forg+2*CO2_forg);O_ud1:= m_trae_toer/M_trae*OprC + (2*CO2+CO+H2O+0.66555*tjaere);

(* massebalance for pyrolyse *)C_ind2:=m_trae_toer/M_trae

11

+ (CO_forg+CO2_forg);C_ud2:= 0.50546*m_trae_toer/M_trae + (CO_pyro+CO2_pyro+CH4_pyro+tjaere_pyro) + (CO_forg+CO2_forg);

H_ind2:=m_trae_toer/M_trae*HprC + (2*H2_forg+2*H2O_forg);H_ud2:= (2*H2_pyro+2*H2O_pyro+4*CH4_pyro+1.5*tjaere_pyro) + (2*H2_forg+2*H2O_forg);

O_ind2:=m_trae_toer/M_trae*OprC + (CO_forg+H2O_forg+2*CO2_forg);O_ud2:= (CO_pyro+H2O_pyro+2*CO2_pyro+0.66555*tjaere_pyro) + (CO_forg+H2O_forg+2*CO2_forg);

(* massebalance for forgasning *)C_ind3:=0.50546*m_trae_toer/M_trae + CO2_ind_forg;C_ud3:= C_ind_burn + (CO_forg+CO2_forg);

H_ind3:=2*H2O_ind_forg;H_ud3:= (2*H2_forg+2*H2O_forg);

O_ind3:=H2O_ind_forg+2*CO2_ind_forg;O_ud3:= (CO_forg+H2O_forg+2*CO2_forg);

(* massebalance for forbrænding *)C_ind4:=C_ind_burn;C_ud4:= C_ind_burn;

H_ind4:=2*H2O_ind_forg;H_ud4:= 2*H2O_ind_forg;

O_ind4:=H2O_ind_forg+2*CO2_ind_forg;O_ud4:= H2O_ind_forg+2*CO2_ind_forg;

(***** ENERGIBALANCE OG UDREGNING AF VARMETAB FOR HELE REAKTOREN *****)(* IND *)H_trae:=m_trae_toer*(h0_trae+cp_trae*(T_trae-T_25));H_vand_trae:=m_trae_fugt*fugtindhold/100*(h0_vand+cp_vand*(T_trae-T_25));H_damp_forg:=m_vand_forg*(h0_damp+cp_damp*(T_forg_ind-T_25));H_luft_forg:=m_luft_forg*(h0_luft+cp_luft*(T_forg_ind-T_25));H_luft_top:=m_luft_top*(h0_luft+cp_luft*(T_luft_top-T_25));

Q_Total_ind:=H_trae+H_vand_trae+H_damp_forg+H_luft_forg+H_luft_top;

(* UD *)H_N2:= N2*(((-6.7373e-7*Tu+3.7142e-3)*Tu+27.3867)*Tu-8492.6);H_H2:= H2*(((2.8541e-7*Tu +7.5371e-4)*Tu +28.1799)*Tu -8468);H_CO:= CO*(((-7.8966e-7*Tu+4.0847e-3)*Tu+27.4025)*Tu-119057.4);H_CH4:= CH4*(((-5.7518E-6*Tu+3.7413E-2)*Tu+13.6969)*Tu-82117.3);H_CO2:= CO2*(((-4.1037e-6*Tu + 0.017087)*Tu+32.5902)*Tu-4.04746e5);H_H2O:= H2O*(((-1.1853e-6*Tu+8.2233e-3)*Tu+29.0266)*Tu-251236.3);H_tjaere:= tjaere*((((-5.22625e-9*Tu+1.89363e-5)*Tu-0.0244395)*Tu+15.2523)*Tu-7430.34);

Q_Total_ud:=H_N2+H_H2+H_CO+H_CH4+H_CO2+H_H2O+H_tjaere;

Q_tab:=Q_Total_ud-Q_Total_ind;

12

(***** ENERGIBALANCE NED GENNEM REAKTOREN *****)(*** Energibalance for fordampningszonen ***)H_trae_ud1:=m_trae_toer*(h0_trae+cp_trae*(T_fordamp-T_25));

H_N2_ud1:= N2*(((-6.7373e-7*Tu+3.7142e-3)*Tu+27.3867)*Tu-8492.6);H_H2_ud1:= H2*(((2.8541e-7*Tu +7.5371e-4)*Tu +28.1799)*Tu -8468);H_CO_ud1:= CO*(((-7.8966e-7*Tu+4.0847e-3)*Tu+27.4025)*Tu-119057.4);H_CH4_ud1:= CH4*(((-5.7518E-6*Tu+3.7413E-2)*Tu+13.6969)*Tu-82117.3);H_CO2_ud1:= CO2*(((-4.1037e-6*Tu + 0.017087)*Tu+32.5902)*Tu-4.04746e5);H_H2O_ud1:= H2O*(((-1.1853e-6*Tu+8.2233e-3)*Tu+29.0266)*Tu-251236.3);H_tjaere_ud1:= tjaere*M_tjaere*((((-5.22625e-9*Tu+1.89363e-5)*Tu-0.0244395)*Tu+15.2523)*Tu-7430.34);H_gas_ud1:=(H_N2+H_H2+H_CO+H_CH4+H_CO2+H_H2O);

H_N2_ind1:= N2*(((-6.7373e-7*T2+3.7142e-3)*T2+27.3867)*T2-8492.6);H_H2_ind1:= (H2_pyro+H2_forg) *(((2.8541e-7*T2 +7.5371e-4)*T2 +28.1799)*T2 -8468);H_CO_ind1:= (CO_pyro+CO_forg) *(((-7.8966e-7*T2+4.0847e-3)*T2+27.4025)*T2-119057.4);H_CH4_ind1:= CH4_pyro *(((-5.7518E-6*T2+3.7413E-2)*T2+13.6969)*T2-82117.3);H_CO2_ind1:= (CO2_pyro+CO2_forg) *(((-4.1037e-6*T2 + 0.017087)*T2+32.5902)*T2-4.04746e5);H_H2O_ind1:= (H2O_pyro+H2O_forg) *(((-1.1853e-6*T2+8.2233e-3)*T2+29.0266)*T2-251236.3);H_tjaere_ind:= tjaere*M_tjaere*((((-5.22625e-9*T2+1.89363e-5)*T2-0.0244395)*T2+15.2523)*T2-7430.34);

H_gas_ind1:=(H_N2_ind1+H_H2_ind1+H_CO_ind1+H_CH4_ind1+H_CO2_ind1+H_H2O_ind1);balance1:= H_trae_ud1+H_gas_ud1-H_trae-H_vand_trae-H_gas_ind1;

(*** Energibalance for pyrolyse-zonen ***)

H_koks_ud2:=0.50546*m_trae_toer/M_trae *(((2.4682e-9*T2-1.3146e-5)*T2+2.795e-2)*T2-4.6904)*T2-759.65;

H_N2_ind2:= N2*(((-6.7373e-7*T3+3.7142e-3)*T3+27.3867)*T3-8492.6);H_H2_ind2:= H2_forg *(((2.8541e-7*T3 +7.5371e-4)*T3 +28.1799)*T3 -8468);H_CO_ind2:= CO_forg *(((-7.8966e-7*T3+4.0847e-3)*T3+27.4025)*T3-119057.4);H_CO2_ind2:= CO2_forg *(((-4.1037e-6*T3 + 0.017087)*T3+32.5902)*T3-4.04746e5);H_H2O_ind2:= H2O_forg *(((-1.1853e-6*T3+8.2233e-3)*T3+29.0266)*T3-251236.3);

H_gas_ind2:=(H_N2_ind2+H_H2_ind2+H_CO_ind2+H_CO2_ind2+H_H2O_ind2);balance2:= H_koks_ud2+H_gas_ind1-H_trae_ud1-H_gas_ind2;

(*** Energibalance for forgasnings-zonen ***)

H_koks_ud3:=C_ind_burn *(((2.4682e-9*T3-1.3146e-5)*T3+2.795e-2)*T3-4.6904)*T3-759.65;

H_N2_ind3:= N2*(((-6.7373e-7*T4+3.7142e-3)*T4+27.3867)*T4-8492.6);H_CO2_ind3:= C_ind_burn *(((-4.1037e-6*T4 + 0.017087)*T4+32.5902)*T4-4.04746e5);H_H2O_ind3:= H2O_ind_forg *(((-1.1853e-6*T4+8.2233e-3)*T4+29.0266)*T4-251236.3);

H_gas_ind3:=(H_N2_ind3+H_CO2_ind3+H_H2O_ind3);

13

balance3:= H_koks_ud3+H_gas_ind2-H_koks_ud2-H_gas_ind3;

(*** Energibalance for forbrændings-zonen ***)

H_gas_ind4:=(H_damp_forg+H_luft_forg);balance4:= H_gas_ind3-H_koks_ud3-H_gas_ind4;

(******************** EKSTERN KRAKNING *************************)(* Gasserne bringes i water-gas shift ligevægt, ligevægt indtræderførst ved temp > 700 grader C *)Ka_krak:=(0.000001303*T_krak+0.000717)*T_krak-1.3006;C_gas:=CO+CO2;O_gas:=CO+2*CO2+H2O;H_gas:=(H2O+H2)*2;a:=Ka_krak-1;b:=Ka_krak*H_gas/2-O_gas*Ka_krak+C_gas*Ka_krak+O_gas;c:=C_gas*C_gas-C_gas*O_gas;D:=b*b-4*a*c;

IF (a < 0) OR (a > 0) THEN (* tager forbehold for div med 0 *) CO2_krak:=(-b+SQRT(D))/(2*a)ELSE CO2_krak:=-c/b;

CO_krak:=C_gas-CO2_krak;H2O_krak:=O_gas-CO_krak-2*CO2_krak;H2_krak:=H_gas/2-H2O_krak;

(*** gassammensætning efter krakning ***)CO_krak_pro:= CO_krak/(CO_krak+H2_krak+H2O_krak+CO2_krak+CH4+N2)*100;H2_krak_pro:= H2_krak/(CO_krak+H2_krak+H2O_krak+CO2_krak+CH4+N2)*100;H2O_krak_pro:= H2O_krak/(CO_krak+H2_krak+H2O_krak+CO2_krak+CH4+N2)*100;CO2_krak_pro:= CO2_krak/(CO_krak+H2_krak+H2O_krak+CO2_krak+CH4+N2)*100;CH4_krak_pro:= CH4/(CO_krak+H2_krak+H2O_krak+CO2_krak+CH4+N2)*100;N2_krak_pro:= N2/(CO_krak+H2_krak+H2O_krak+CO2_krak+CH4+N2)*100;

(* output specification *)

write(10,tjaere,H2O,N2);write(10,CO,H2,CO2,CH4);write(1,gasprod,T_forg_ind,T_dugpunkt);write(10,braend_gas,braend_tjaere,N2_pro);write(10,CO_pro,H2_pro,H2O_pro,CO2_pro,CH4_pro);

END.$GRCOM=xaxis(0:4000:-4:2,' Temp (K)');yaxis(0:50:-10:2,' Gassammen')

14

15

APPENDIKS 2

HARBOØRE-MODEL

PROGRAMUDSKRIFT MED PYROLYSEMODEL 2

16

$TITLE= Harboøre / DTU

(* Stationær model af Harboøre forgasseren (indfødt 278000 kJ/h) model, der finder massestrømmene af vanddamp og produktgas ud af reaktoren, massestrømmen af den tilsatte luft til topbrænderen samt temperaturen af forgasningsmidlet og et estimat for varmetabet *)

(* Pyrolysemodel på basis af Hald *)

BEGIN

(************************* ERKLÆRINGER ***************************)

PARAMETER

(* biomasse *)m_trae_fugt(312.5), (* massestroem af fugtig flis, [kg/h] *)fugtindhold(30), (* fugtindhold i flis, [%] *)OprC(0.66), (* ilt-indhold i trae i fht. C, [-] *)HprC(1.4515), (* brint-indhold i trae i fht. C, [-] *)

(* forgasningsmiddel *)m_vand_forg(59.4), (* massestroem af vand, [kg/h] *)V_luft_forg(222), (* Volumenstroem af toer luft, [Nm3/h] *)p_total(1.01325E5), (* totaltryk = 101325 Pa *)Rho_luft(1.293), (* massefylde af toer luft v. 0 grader C *)

(* luft til topbrænder *)m_luft_top(54.3),

(* Overhedning af forgasningsmidlet, fast temperatur *) (* Temp. af forgasningsmiddel efter overhed, [K] *) (* Sættes til 0, hvis der ikke ønskes overhedning *)T_overhed(340),

(* Temperaturer, K *)T_trae(298.15), (* Temperaturen af indfødt træ, [K] *)T_luft_top(298.15), (* Temperaturen af luft til topbrænder, [K] *)T_fordamp(373.15), (* Temperaturen ved fordampning af vand, [K] *)Tu(393), (* Temperaturen ud af reaktor, [K] *)T2(808), (* Temperaturen i pyrolyse-zone, [K] *)T3(1073), (* Temperaturen i forgasnings-zone, [K] *)T4(2200), (* Temperaturen i forbrændings-zone, [K] *)T_0(273.15), (* Temperatur ved normaltilstand, 0 C *)T_25(298.15), (* Temperatur ved standardtilstand, 25 C *)

(* gasserne (ideal gas) *)K_N2(0.768), (* andel af N2 i luft, massebasis *)R_H2O(461.4), (* Gaskonstanten for damp, J/(kg*K) *)c_ideal(44.62), (* antal mol pr Nm3 idealgas *)M_N2(28E-3), (* molvaegten af N2 *)M_CO(28E-3), (* molvaegten af CO *)M_H2(2E-3), (* molvaegten af H2 *)M_O2(32E-3), (* molvaegten af O2 *)M_CO2(44E-3), (* molvaegten af CO2 *)M_CH4(16E-3), (* molvaegten af CH4 *)M_H2O(18E-3), (* molvaegten af H2O *)

(* beregning af nedre braendvaerdi *)h0_CO(283.0), (* kJ/mol *)h0_H2(241.9), (* kJ/mol *)

17

h0_CH4(802.5), (* kJ/mol *)h0_tjaere(25), (* MJ/kg *)

(*** Energibalance og udregning af varmetab ***)

(* Nulpunktsentalpier, J/kg *)h0_trae(-5.280E6),h0_vand(-15.87E6),h0_damp(-13.42E6),h0_luft(0),

(* Varmefylder, J/(kg*K) *)cp_trae(2260),cp_vand(4200),cp_damp(2026),cp_luft(1051),

(*** Atombalance ***)M_C(12E-3), (* Kg/mol *)M_H(1E-3),M_O(16E-3),M_N(14E-3),

(*** Ekstern krakning ***)T_krak(1073); (* Kraknings-temperatur *)

VARIABLE (* brændsel *)m_trae_toer, (* massestroemmen af toert trae *)M_trae, (* molvægten af træ *)

(* forgasningsmiddel *)T_forg_ind, (* Temperaturen af forgasningsmidlet, K *)T_dugpunkt, (* Dugpunktstemp. af forgasningsmidlet, K *)m_luft_forg, (* massestroem af forgasnings luft, kg/h *)x, (* absolut fugtighed *)p_damp(2E4), (* damptrykket i den fugtige luft, Pa *)

M_tjaere, (* molvægten af tjære *)

(* stofbalance for forbrændings-zonen *)C_ind_burn, CO2_ud_burn,

(* stofbalancer for forgasnings-zonen *)CO2_ind_forg, H2O_ind_forg,C_ind_forg, C_ud_forg, H_ud_forg, O_ud_forg,

(* variable til at bestemme gas-ligevægten i forgasnings-zonen *)a1(0.01), Ka,est_CO, est_H2, est_CO2, est_H2O,

(* ligevaegtskonc. af CO, H2, CO2, H2O i forgasnings-zonen *)CO_forg(0:), H2_forg(0:), CO2_forg(0:), H2O_forg(0:),

(* gasproduktion i pyrolyse-zonen *)CO_pyro, CO2_pyro, CH4_pyro, H2_pyro, H2O_pyro, tjaere_pyro,

(* vanddamp tilført i tørrings-zonen *)H2O_toerring,

(* gassammensætning efter reaktoren *)CO_reaktor, H2_reaktor, H2O_reaktor, CO2_reaktor, CH4_reaktor, N2_reaktor,

18

(* gassammensætning efter topbrænder *)O2_top, N2_top, stoek_gas, stoek_tjaere, stoek_lige,CO2_top, H2O_top, CO_burn_top, H2_burn_top, CH4_burn_top, tjaere_burn_top,

(* endelig gassammensætning [mol] *)CO, H2, H2O, CO2, CH4, N2, tjaere, gasprod,

(* endelig gassammensætning [%] *)CO_pro, H2_pro, CO2_pro, H2O_pro, CH4_pro, N2_pro,

(* beregning af nedre braendvaerdi *)braend_gas, (* MJ/Nm3 *)braend_tjaere, (* MJ/Nm3 *)

(******************* KONTROL *******************)

(***************** MASSEBALANCER *****************)

(*** Total atombalance ***)

(* IND *)C_ind, H_ind, O_ind, N_ind, M_total_ind,

(* UD *)C_ud, H_ud, O_ud, N_ud,

(*** atombalance ned gennem reaktoren ***)C_ind1, H_ind1, O_ind1, C_ud1, H_ud1, O_ud1, (* tørring *)C_ind2, H_ind2, O_ind2, C_ud2, H_ud2, O_ud2, (* pyrolyse *)C_ind3, H_ind3, O_ind3, C_ud3, H_ud3, O_ud3, (* forgasning *)C_ind4, H_ind4, O_ind4, C_ud4, H_ud4, O_ud4, (* forbrænding *)

(***** ENERGIBALANCE OG UDREGNING AF VARMETAB *****)

(* samlede entalpier, ind, [J/h] *)H_trae, H_vand_trae, H_damp_forg, H_luft_forg, H_luft_top, Q_Total_ind,

(* samlede entalpier, ud, [J/h] *)H_N2, H_H2, H_CO, H_CH4, H_CO2, H_H2O, H_tjaere, Q_Total_ud, Q_tab,

(*** ENERGIBALANCE NED GENNEM REAKTOREN ***)

(*** tørring ***)H_trae_ud1,H_N2_ud1, H_H2_ud1, H_CO_ud1, H_CH4_ud1,H_CO2_ud1, H_H2O_ud1, H_tjaere_ud1, H_gas_ud1,

H_N2_ind1, H_H2_ind1, H_CO_ind1, H_CH4_ind1,H_CO2_ind1, H_H2O_ind1, H_tjaere_ind, H_gas_ind1,balance1,

(*** pyrolyse ***)H_koks_ud2,H_N2_ind2, H_H2_ind2, H_CO_ind2, H_CO2_ind2, H_H2O_ind2, H_gas_ind2,balance2,

(*** forgasning ***)H_koks_ud3,H_N2_ind3, H_CO2_ind3, H_H2O_ind3, H_gas_ind3,balance3,

(*** forbrænding ***)

19

H_gas_ind4,balance4,

(*** Ekstern krakning ***)Ka_krak,C_gas, O_gas, H_gas,a, b, c, D, (* variable til løsning af 2. grads-lign *)

(* ligevaegtskonc. af CO2, CO, H2, H2O efter krakning, hhv i mol og procent *)CO2_krak(0:), CO_krak(0:), H2_krak(0:),H2O_krak(0:),CO_krak_pro, H2_krak_pro, CO2_krak_pro, H2O_krak_pro, CH4_krak_pro, N2_krak_pro;

(************************ PROGRAMMET STARTER **************************)

(***** Blandet *****)

(* Molvægten af træ (pr. C) på basis af atomar sammensætning *)M_trae:=1*M_C+HprC*M_H+OprC*M_O;

(* Bestemmelse af massestrømme af tørt træ og forgasningsluft *)m_trae_toer:= m_trae_fugt*(100-fugtindhold)/100;m_luft_forg:= V_luft_forg*Rho_luft;

(***** Temperaturen af forgasningsmidlet bestemmes (før overhedning) *****)(***** Mættet vanddamps temperatur som funktion af trykket *****)x:=m_vand_forg/m_luft_forg;0:=0.62198*(p_damp/(p_total-p_damp))-x;T_dugpunkt:=37.58-(4042.9/(LOG(p_damp)-23.5771));

(* programmet benytter den højeste af de to temperaturer: T_dugpunkt eller T_overhed som værdi for T_forg_ind *)IF (T_dugpunkt > T_overhed) Then T_forg_ind:= T_dugpunktElse T_forg_ind:= T_overhed;

(***** Modellering af forgasningsreaktoren *****)

(*** FORBRÆNDINGS-ZONEN ***)(*** atombalance for forbrænding ***)(* C omdannes til CO2 ved støkiometrisk afbrænding med den tilsatte forgasningsluft *)

C_ind_burn:=0.5*2*0.21*V_luft_forg*c_ideal;CO2_ud_burn:=C_ind_burn;(*** Forbrænding slut ***)

(*** FORGASNINGS-ZONEN ***)(*** atombalance for forgasning ***)(* C omdannes til CO og H2 efter reaktion med CO2 fra afbrændingszonen og H2O fra den tilsatte forgasningsluft, noget af kulstoffet fortsætter ned i forbrændingszonen *)

CO2_ind_forg:=CO2_ud_burn;H2O_ind_forg:=m_vand_forg/M_H2O;

20

(* netto input af fast kulstof (ind-ud) *)(* kulstof, massebalance på basis af Hald *)C_ind_forg:=0.50546*m_trae_toer/M_trae - C_ind_burn;C_ud_forg:=C_ind_forg + CO2_ind_forg;H_ud_forg:=2*H2O_ind_forg;O_ud_forg:=2*CO2_ind_forg + H2O_ind_forg;

(*** Gasserne i ligevægt iflg. Water-gas shift reaktionen ***)

(* ligevægtskonstant, Ka(T) *)Ka:=(0.000001303*T3+0.000717)*T3-1.3006;

(* forskellige startgæt på gassammensætningen *)(* bemærk, at hvis O_ud_forg < C_ud_forg skal der dannes metan, hvilket modellen IKKE tager hensyn til *)

IF O_ud_forg < 2*C_ud_forg THEN BEGIN est_CO:=2*C_ud_forg - O_ud_forg; est_CO2:=O_ud_forg - C_ud_forg; est_H2O:=0; est_H2:=H_ud_forg/2 ENDELSE BEGIN est_CO2:=C_ud_forg/2; est_CO:=est_CO2; est_H2O:=O_ud_forg - 3*est_CO2; est_H2:=(H_ud_forg - 2*est_H2O)/2 END;

0 :=(est_H2O+a1)*(est_CO+a1) /((est_CO2-a1)*(est_H2-a1))-Ka;

CO_forg :=est_CO+a1;H2_forg :=est_H2-a1;CO2_forg :=est_CO2-a1;H2O_forg :=est_H2O+a1;(*** Forgasning slut ***)

(*** PYROLYSE-ZONEN ***)(* fastholdt CH4, H2O og tjære *)CO_pyro:= 0.3561*m_trae_toer/M_trae;CO2_pyro:= 0.0000*m_trae_toer/M_trae;CH4_pyro:= 0.1053*m_trae_toer/M_trae;H2_pyro:= 0.2083*m_trae_toer/M_trae;H2O_pyro:= 0.2785*m_trae_toer/M_trae;tjaere_pyro:=0.0382*m_trae_toer/M_trae;(*** pyrolysen stopper ***)

(*** TØRRINGS-ZONEN ***)H2O_toerring:=m_trae_fugt*fugtindhold/100/M_H2O;(*** tørringen stopper ***)

(*** udregning af gassammensætning efter reaktor ***)CO_reaktor:=CO_forg+CO_pyro;H2_reaktor:=H2_forg+H2_pyro;H2O_reaktor:=H2O_forg+H2O_pyro+H2O_toerring;CO2_reaktor:=CO2_forg+CO2_pyro;CH4_reaktor:=CH4_pyro;

21

N2_reaktor:=2*0.79*V_luft_forg*c_ideal/2;

(*** støkiometrisk afbrænding i topbrænderen ***)O2_top:= (1-K_N2)*m_luft_top/M_O2;N2_top:= K_N2*m_luft_top/M_N2;stoek_gas:= 2*CH4_reaktor + (CO_reaktor + H2_reaktor)/2;stoek_tjaere:= 1.042225*tjaere_pyro;stoek_lige:= stoek_gas + stoek_tjaere;

(*** Herunder kommer 3 forskellige modeller for afbrænding i top- brænderen. Først en model, hvor bare gassen afbrændes støkiometrisk. Dernæst en model hvor kun tjæren afbrændes og endelig en model, hvor både gas og tjære afbrændes støkiometrisk ***) (* De to modeller der ikke benyttes, skal kommenteres ud *)

(* model 1 *)

CO_burn_top:= O2_top/stoek_gas*CO_reaktor;H2_burn_top:= O2_top/stoek_gas*H2_reaktor;CH4_burn_top:= O2_top/stoek_gas*CH4_reaktor;tjaere_burn_top:=0;CO2_top:= CH4_burn_top + CO_burn_top;H2O_top:= 2*CH4_burn_top + H2_burn_top;

(* model 2 *)(*IF stoek_tjaere > O2_top THEN BEGIN CO_burn_top:= 0; H2_burn_top:= 0; CH4_burn_top:= 0; tjaere_burn_top:=O2_top/stoek_tjaere*tjaere_pyro; CO2_top:= 1*tjaere_burn_top; H2O_top:= 0.75*tjaere_burn_top ENDELSE BEGIN CO_burn_top:= (O2_top-stoek_tjaere)/stoek_gas*CO_reaktor; H2_burn_top:= (O2_top-stoek_tjaere)/stoek_gas*H2_reaktor; CH4_burn_top:= (O2_top-stoek_tjaere)/stoek_gas*CH4_reaktor; tjaere_burn_top:=tjaere_pyro; CO2_top:= (1*tjaere_pyro) + CH4_burn_top + CO_burn_top; H2O_top:= (0.75*tjaere_pyro) + 2*CH4_burn_top + H2_burn_top END;*)

(* model 3 *)(*CO_burn_top:= O2_top/stoek_lige*CO_reaktor;H2_burn_top:= O2_top/stoek_lige*H2_reaktor;CH4_burn_top:= O2_top/stoek_lige*CH4_reaktor;tjaere_burn_top:=O2_top/stoek_lige*tjaere_pyro;CO2_top:= 1*tjaere_burn_top + CH4_burn_top + CO_burn_top;H2O_top:= 0.75*tjaere_burn_top + 2*CH4_burn_top + H2_burn_top;*)

(* model uden topbrænder *)(*CO_burn_top:= 0;H2_burn_top:= 0;CH4_burn_top:= 0;tjaere_burn_top:=0;

22

CO2_top:= 0;H2O_top:= 0;*)

(*** udregning af gassammensætning efter topbrænder ***)CO:=CO_reaktor-CO_burn_top;H2:=H2_reaktor-H2_burn_top;H2O:=H2O_reaktor+H2O_top;CO2:=CO2_reaktor+CO2_top;CH4:=CH4_reaktor-CH4_burn_top;N2:=N2_reaktor+N2_top;tjaere:=tjaere_pyro-tjaere_burn_top;Gasprod:=(CO+H2+H2O+CO2+CH4+N2)/c_ideal;

(*** gassammensætning efter topbrænder i procent ***)CO_pro:= CO/(CO+H2+H2O+CO2+CH4+N2)*100;H2_pro:= H2/(CO+H2+H2O+CO2+CH4+N2)*100;H2O_pro:= H2O/(CO+H2+H2O+CO2+CH4+N2)*100;CO2_pro:= CO2/(CO+H2+H2O+CO2+CH4+N2)*100;CH4_pro:= CH4/(CO+H2+H2O+CO2+CH4+N2)*100;N2_pro:= N2/(CO+H2+H2O+CO2+CH4+N2)*100;

(*** beregning af nedre braendvaerdi ***)braend_gas:=(CO_pro*h0_CO+H2_pro*h0_H2+CH4_pro*h0_CH4)/100*c_ideal/1000;M_tjaere:= (1*M_C+1.5*M_H+0.66555*M_O);braend_tjaere:=tjaere*M_tjaere/Gasprod*h0_tjaere;

(*************************** KONTROL ****************************)

(***** Atombalance for hele reaktoren *****)(* IND *)C_ind:=m_trae_toer/M_trae;

H_ind:=m_trae_toer/M_trae*HprC +2*m_trae_fugt*fugtindhold/100/M_H2O +2*m_vand_forg/M_H2O;O_ind:=m_trae_toer/M_trae*OprC +m_trae_fugt*fugtindhold/100/M_H2O +m_vand_forg/M_H2O +2*0.21*V_luft_forg*c_ideal +2*(1-K_N2)*m_luft_top/M_O2;

N_ind:=2*0.79*V_luft_forg*c_ideal +2*K_N2*m_luft_top/M_N2;

M_total_ind:=C_ind*M_C+H_ind*M_H +O_ind*M_O+N_ind*M_N;

(* UD *) (*** atombalance efter topbrænder ***)C_ud:=CO+CO2+CH4+tjaere;H_ud:=2*H2+2*H2O+4*CH4+1.5*tjaere;O_ud:=CO+2*CO2+H2O+0.66555*tjaere;N_ud:=2*N2;

(***** MASSEBALANCER NED GENNEM REAKTOREN *****)(* massebalance for fordampning *)C_ind1:=m_trae_toer/M_trae + (CO_pyro+CO2_pyro+CH4_pyro+tjaere_pyro) + (CO_forg+CO2_forg);C_ud1:= m_trae_toer/M_trae + CO+CO2+CH4+tjaere;

23

H_ind1:=m_trae_toer/M_trae*HprC + 2*m_trae_fugt*fugtindhold/100/M_H2O + (2*H2_pyro+2*H2O_pyro+4*CH4_pyro+1.5*tjaere_pyro) + (2*H2_forg+2*H2O_forg);H_ud1:= m_trae_toer/M_trae*HprC + (2*H2+2*H2O+4*CH4+1.5*tjaere);

O_ind1:=m_trae_toer/M_trae*OprC + m_trae_fugt*fugtindhold/100/M_H2O + (CO_pyro+H2O_pyro+2*CO2_pyro+0.66555*tjaere_pyro) + (CO_forg+H2O_forg+2*CO2_forg);O_ud1:= m_trae_toer/M_trae*OprC + (2*CO2+CO+H2O+0.66555*tjaere);

(* massebalance for pyrolyse *)C_ind2:=m_trae_toer/M_trae + (CO_forg+CO2_forg);C_ud2:= 0.50546*m_trae_toer/M_trae + (CO_pyro+CO2_pyro+CH4_pyro+tjaere_pyro) + (CO_forg+CO2_forg);

H_ind2:=m_trae_toer/M_trae*HprC + (2*H2_forg+2*H2O_forg);H_ud2:= (2*H2_pyro+2*H2O_pyro+4*CH4_pyro+1.5*tjaere_pyro) + (2*H2_forg+2*H2O_forg);

O_ind2:=m_trae_toer/M_trae*OprC + (CO_forg+H2O_forg+2*CO2_forg);O_ud2:= (CO_pyro+H2O_pyro+2*CO2_pyro+0.66555*tjaere_pyro) + (CO_forg+H2O_forg+2*CO2_forg);

(* massebalance for forgasning *)C_ind3:=0.50546*m_trae_toer/M_trae + CO2_ind_forg;C_ud3:= C_ind_burn + (CO_forg+CO2_forg);

H_ind3:=2*H2O_ind_forg;H_ud3:= (2*H2_forg+2*H2O_forg);

O_ind3:=H2O_ind_forg+2*CO2_ind_forg;O_ud3:= (CO_forg+H2O_forg+2*CO2_forg);

(* massebalance for forbrænding *)C_ind4:=C_ind_burn;C_ud4:= C_ind_burn;

H_ind4:=2*H2O_ind_forg;H_ud4:= 2*H2O_ind_forg;

O_ind4:=H2O_ind_forg+2*CO2_ind_forg;O_ud4:= H2O_ind_forg+2*CO2_ind_forg;

(***** ENERGIBALANCE OG UDREGNING AF VARMETAB FOR HELE REAKTOREN *****)(* IND *)H_trae:=m_trae_toer*(h0_trae+cp_trae*(T_trae-T_25));H_vand_trae:=m_trae_fugt*fugtindhold/100*(h0_vand+cp_vand*(T_trae-T_25));H_damp_forg:=m_vand_forg*(h0_damp+cp_damp*(T_forg_ind-T_25));H_luft_forg:=m_luft_forg*(h0_luft+cp_luft*(T_forg_ind-T_25));H_luft_top:=m_luft_top*(h0_luft+cp_luft*(T_luft_top-T_25));

Q_Total_ind:=H_trae+H_vand_trae+H_damp_forg+H_luft_forg+H_luft_top;

24

(* UD *)H_N2:= N2*(((-6.7373e-7*Tu+3.7142e-3)*Tu+27.3867)*Tu-8492.6);H_H2:= H2*(((2.8541e-7*Tu +7.5371e-4)*Tu +28.1799)*Tu -8468);H_CO:= CO*(((-7.8966e-7*Tu+4.0847e-3)*Tu+27.4025)*Tu-119057.4);H_CH4:= CH4*(((-5.7518E-6*Tu+3.7413E-2)*Tu+13.6969)*Tu-82117.3);H_CO2:= CO2*(((-4.1037e-6*Tu + 0.017087)*Tu+32.5902)*Tu-4.04746e5);H_H2O:= H2O*(((-1.1853e-6*Tu+8.2233e-3)*Tu+29.0266)*Tu-251236.3);H_tjaere:= tjaere*((((-5.22625e-9*Tu+1.89363e-5)*Tu-0.0244395)*Tu+15.2523)*Tu-7430.34);

Q_Total_ud:=H_N2+H_H2+H_CO+H_CH4+H_CO2+H_H2O+H_tjaere;

Q_tab:=Q_Total_ud-Q_Total_ind;

(***** ENERGIBALANCE NED GENNEM REAKTOREN *****)(*** Energibalance for fordampningszonen ***)H_trae_ud1:=m_trae_toer*(h0_trae+cp_trae*(T_fordamp-T_25));

H_N2_ud1:= N2*(((-6.7373e-7*Tu+3.7142e-3)*Tu+27.3867)*Tu-8492.6);H_H2_ud1:= H2*(((2.8541e-7*Tu +7.5371e-4)*Tu +28.1799)*Tu -8468);H_CO_ud1:= CO*(((-7.8966e-7*Tu+4.0847e-3)*Tu+27.4025)*Tu-119057.4);H_CH4_ud1:= CH4*(((-5.7518E-6*Tu+3.7413E-2)*Tu+13.6969)*Tu-82117.3);H_CO2_ud1:= CO2*(((-4.1037e-6*Tu + 0.017087)*Tu+32.5902)*Tu-4.04746e5);H_H2O_ud1:= H2O*(((-1.1853e-6*Tu+8.2233e-3)*Tu+29.0266)*Tu-251236.3);H_tjaere_ud1:= tjaere*M_tjaere*((((-5.22625e-9*Tu+1.89363e-5)*Tu-0.0244395)*Tu+15.2523)*Tu-7430.34);H_gas_ud1:=(H_N2+H_H2+H_CO+H_CH4+H_CO2+H_H2O);

H_N2_ind1:= N2*(((-6.7373e-7*T2+3.7142e-3)*T2+27.3867)*T2-8492.6);H_H2_ind1:= (H2_pyro+H2_forg) *(((2.8541e-7*T2 +7.5371e-4)*T2 +28.1799)*T2 -8468);H_CO_ind1:= (CO_pyro+CO_forg) *(((-7.8966e-7*T2+4.0847e-3)*T2+27.4025)*T2-119057.4);H_CH4_ind1:= CH4_pyro *(((-5.7518E-6*T2+3.7413E-2)*T2+13.6969)*T2-82117.3);H_CO2_ind1:= (CO2_pyro+CO2_forg) *(((-4.1037e-6*T2 + 0.017087)*T2+32.5902)*T2-4.04746e5);H_H2O_ind1:= (H2O_pyro+H2O_forg) *(((-1.1853e-6*T2+8.2233e-3)*T2+29.0266)*T2-251236.3);H_tjaere_ind:= tjaere*M_tjaere*((((-5.22625e-9*T2+1.89363e-5)*T2-0.0244395)*T2+15.2523)*T2-7430.34);

H_gas_ind1:=(H_N2_ind1+H_H2_ind1+H_CO_ind1+H_CH4_ind1+H_CO2_ind1+H_H2O_ind1);balance1:= H_trae_ud1+H_gas_ud1-H_trae-H_vand_trae-H_gas_ind1;

(*** Energibalance for pyrolyse-zonen ***)

H_koks_ud2:=0.50546*m_trae_toer/M_trae *(((2.4682e-9*T2-1.3146e-5)*T2+2.795e-2)*T2-4.6904)*T2-759.65;

H_N2_ind2:= N2*(((-6.7373e-7*T3+3.7142e-3)*T3+27.3867)*T3-8492.6);H_H2_ind2:= H2_forg *(((2.8541e-7*T3 +7.5371e-4)*T3 +28.1799)*T3 -8468);H_CO_ind2:= CO_forg *(((-7.8966e-7*T3+4.0847e-3)*T3+27.4025)*T3-119057.4);H_CO2_ind2:= CO2_forg *(((-4.1037e-6*T3 + 0.017087)*T3+32.5902)*T3-4.04746e5);H_H2O_ind2:= H2O_forg *(((-1.1853e-6*T3+8.2233e-3)*T3+29.0266)*T3-251236.3);

25

H_gas_ind2:=(H_N2_ind2+H_H2_ind2+H_CO_ind2+H_CO2_ind2+H_H2O_ind2);balance2:= H_koks_ud2+H_gas_ind1-H_trae_ud1-H_gas_ind2;

(*** Energibalance for forgasnings-zonen ***)

H_koks_ud3:=C_ind_burn *(((2.4682e-9*T3-1.3146e-5)*T3+2.795e-2)*T3-4.6904)*T3-759.65;

H_N2_ind3:= N2*(((-6.7373e-7*T4+3.7142e-3)*T4+27.3867)*T4-8492.6);H_CO2_ind3:= C_ind_burn *(((-4.1037e-6*T4 + 0.017087)*T4+32.5902)*T4-4.04746e5);H_H2O_ind3:= H2O_ind_forg *(((-1.1853e-6*T4+8.2233e-3)*T4+29.0266)*T4-251236.3);

H_gas_ind3:=(H_N2_ind3+H_CO2_ind3+H_H2O_ind3);balance3:= H_koks_ud3+H_gas_ind2-H_koks_ud2-H_gas_ind3;

(*** Energibalance for forbrændings-zonen ***)

H_gas_ind4:=(H_damp_forg+H_luft_forg);balance4:= H_gas_ind3-H_koks_ud3-H_gas_ind4;

(******************** EKSTERN KRAKNING *************************)(* Gasserne bringes i water-gas shift ligevægt, ligevægt indtræderførst ved temp > 700 grader C *)Ka_krak:=(0.000001303*T_krak+0.000717)*T_krak-1.3006;C_gas:=CO+CO2;O_gas:=CO+2*CO2+H2O;H_gas:=(H2O+H2)*2;a:=Ka_krak-1;b:=Ka_krak*H_gas/2-O_gas*Ka_krak+C_gas*Ka_krak+O_gas;c:=C_gas*C_gas-C_gas*O_gas;D:=b*b-4*a*c;

IF (a < 0) OR (a > 0) THEN (* tager forbehold for div med 0 *) CO2_krak:=(-b+SQRT(D))/(2*a)ELSE CO2_krak:=-c/b;

CO_krak:=C_gas-CO2_krak;H2O_krak:=O_gas-CO_krak-2*CO2_krak;H2_krak:=H_gas/2-H2O_krak;

(*** gassammensætning efter krakning ***)CO_krak_pro:= CO_krak/(CO_krak+H2_krak+H2O_krak+CO2_krak+CH4+N2)*100;H2_krak_pro:= H2_krak/(CO_krak+H2_krak+H2O_krak+CO2_krak+CH4+N2)*100;H2O_krak_pro:= H2O_krak/(CO_krak+H2_krak+H2O_krak+CO2_krak+CH4+N2)*100;CO2_krak_pro:= CO2_krak/(CO_krak+H2_krak+H2O_krak+CO2_krak+CH4+N2)*100;CH4_krak_pro:= CH4/(CO_krak+H2_krak+H2O_krak+CO2_krak+CH4+N2)*100;N2_krak_pro:= N2/(CO_krak+H2_krak+H2O_krak+CO2_krak+CH4+N2)*100;

(* output specification *)

write(10,M_tjaere,tjaere,H2O,N2);write(10,CO,H2,CO2,CH4);write(1,gasprod,T_forg_ind,T_dugpunkt);write(10,braend_gas,braend_tjaere,N2_pro);write(10,CO_pro,H2_pro,H2O_pro,CO2_pro,CH4_pro);

END.$GRCOM=xaxis(0:4000:-4:2,' Temp (K)');yaxis(0:50:-10:2,' Gassammen')

26

27

APPENDIKS 3

Dynamic Modelling of the Two-stageGasification Process

28

Dynamic Modelling of the Two-stage Gasification Process

B. Gøbela, J. D. Bentzen

b, U. Henriksen

a and N. Houbak

a

aDepartment of Energy Engineering, Technical University of Denmark,

Building 403 (120), DK-2800 Lyngby, Denmark, E-mail: bg@et.dtu.dk

bCOWI - Consulting Engineers and Planners AS, Parallelvej 15,

DK-2800 Lyngby, Denmark, E-mail : jdb@cowi.dk

ABSTRACT

A two-stage gasification pilot plant was designed and built as a co-operative projectbetween the Technical University of Denmark and the company REKA.

A dynamic, mathematical model of the two-stage pilot plant was developed to serve as atool for optimising the process and the operating conditions of the gasification plant.

The model consists of modules corresponding to the different elements in the plant. Themodules are coupled together through mass and heat conservation.

Results from the model are compared with experimental data obtained during steady andunsteady operation of the pilot plant. A good agreement between the numerical results and theexperimental data is obtained.

The mathematical model prescribes that the plant reaches a new steady-state condition fast,when changing the operating condition from full l oad to partial load.

1. introduction

The two-stage gasification process1 have been developed at the Department of EnergyEngineering, Technical University of Denmark. In 1993 the Department of EnergyEngineering in co-operation with Maskinfabrikken REKA AS designed and built a 400 kWpilot plant based on the two-stage gasification process. In order to describe the dynamicbehaviour of the two-stage gasifier it was decided to establish a dynamic mathematicalmodel2 of the entire system.

29

2. TWO-STAGE GASIFICATION PROCESS

The process is presented in figure 1 and consists of an externally heated pyrolysis unit(heated by exhaust gas from the engine), an oxidation zone, where a partial combustion of thepyrolysis gas takes place, a down-draft char gasifier, a gas cleaning system (based on aventuri scrubber), a gas storage and an internal-combustion engine with electric generator. Inorder to recover the considerable quantities of energy contained in the hot gas streams, severalheat exchangers are included.

The plant is operated with wood chips as fuel.

Figure 1. Two-stage gasification process used at the pilot plant in Aars, Denmark

super-heatedsteam

preheated air

hot gas

��������� ������

partialoxidationpyrolysis

feeding system

gasificationof char

exhaust gas

ash

districtheating

~

gasengine

electricity

gasstorage cold gas

exhaust gas

pyrolysis productsproducer gas district

heating

air preheat

stack

evaporation superheatingwater

district heating

air A.

A.

30

3. DESCRIPTION OF THE DYNAMIC MODEL

Modelli ng the two-stage gasification pilot plant is done by splitti ng the system in principalcomponents. The main components are described in subprograms and combined to an overallmathematical model of the plant, which gives a description of the dynamic in and between theelements.

Dividing the system in to modules has the advantage that it is simple to change the modelif the plant is rebuilt or improved models are developed.

The model is generally based on the conservation of energy:

( ) ( )∂∂

∂∂t

Mux

mh dx Q∑ ∑+ =

(1)

and conservation of mass:

∂∂M

t∑ + ∑∂∂

m

xdx =0 (2)

Where M is the mass,

m is mass flow, h the enthalpy, u internal energy and

Q is the amountof transferred heat. t and x is the time and position coordinates.

3.1 Pyrolysis tubeWood chips are supplied with a screw feeder and a rotary sealing valve. In the pyrolysis

tube the biomass is carried forward by a screw conveyor and is externally heated by exhaustgas from the engine.

The modelli ng of the pyrolysis tube includes descriptions of conduction, convection andradiation3. A function describing the pyrolysis process depending on temperature, T,(equation 3) has been created, based on pyrolysis data obtained earlier4. Here Wvol refers tothe amount of volatiles retained in the solid phase during the pyrolysis. This value has beennormalised relative to the initial volatile content in the biomass particle.

1050400

423 400

050 050 423 400423 823

W T)

dW T)

dT

KSin T K K

Cos T K KK T K

vol

vol

(

(,

(( ) / )

, , (( ) / ),⋅ =

−⋅

⋅ − ⋅

+ ⋅ − ⋅≤ <

ππ

π(3)

3.2 Par tial oxidationSuperheated steam and preheated air are added in the top of the gasifier. A part of the

volatiles is burned, resulting in a major increase in the temperature. This high temperaturezone serves as a heat source for the gasification process. Further, a large fraction of the tars,produced in the pyrolysis process are cracking here. The modelli ng is based on equation 1 and2 coupled with the water-gas shift reaction.

31

3.3 Char gasificationThe char generated in the pyrolysis process falls down in the gasifier and forms a char bed.

The hot gas stream from the oxidation zone, flows through the bed, and reacts with the char,resulting in combustible gasses, the so-called product gas.

The gasification module is described by the water-gas shift reaction and the charreactivity that is measured5 in a TGA apparatus and adjusted to the actual gasificationconditions. The reactivity expression, Rchar, is approximated by the following power function,equation (4). The reason for this approximation is that it permits to make a semi-analyticintegration, eqaution (5).

R T) A edw

dt wbT bT(x Tchar

E

R T char

char

a achar( , )= ⋅ = ⋅ ≈ =−⋅ 1

0 (4)

where A is the frequency factor, E the activation energy, R the gas constant,wchar is the amount of char, a and b are constants and T0 is temperature in the top of the charbed.

Based on the reactivity given in equation (4), a semi-analytic integration across the totalchar bed has been made giving the total conversion of char as:

( )( )dWdt

mc

hT x T Tkoks

p

koks

=−

−�

,∆ 0 0

(5)

Where Wkoks is the total amount of char in the bed, cp is the specific heat capacity and ∆hkoksthe reaction energy of the char conversion under gasification.

3.4 System of heat exchangersFirst, the product gas heats the exhaust gas, second it preheats the air for the partial

oxidation, and finally it exchanges heat with the district heating system.The heat exchanger module are described by use of the Number of Transfer Units method.

3.5 Gas cleaning, gas storage, and engineThe system of heat exchangers chill s the product gas to a temperature below 50–60 °C. In

the gas cleaning system the gas is purified by passing a venturi scrubber. A roots blower boostthe gas to the gas storage. A gas engine operates a synchronous generator. The coolant circuitis utili sed for district heating. These elements are modelled by use of mass and energyconservation, equations (1) and (2). For the engine these equations are combined with aneff iciency factor.

32

4. SIMULATION

The resulting dynamic model consists of a system of non-linear algebraic equations coupledwith ordinary and partial differential equations. To solve this system of equations SIL6 hasbeen used, a simulation language for solving a system of non-linear algebraic equations andordinary differential equations. The partial differential equations are solved by the finite-difference method.

5. RESULT S OF MODEL CALCULATIONS, COMPARISON WITH EXPERIMENTS

In order to validate the model, experimental data have been compared with a computersimulation. The operation conditions from the pilot plant are used as input data. Theexperimental data are obtained during normal operation of the pilot plant. A step change ofthe flows of biomass and air is introduced at 13 o’clock. Figure 2 demonstrates a goodagreement between the model and results obtained at the pilot plant.

Figure 2. Measured gas composition in service compared with modelli ng results.

5.1 PARAMETER ANALYSISThe mathematical model is now used to investigate the gasifier behaviour subjected to a

sudden change in operating conditions. The gasifier is operating at full l oad, and then after 5hours, the biomass and steam input are reduced by 50 %, and the air input is reduced by 45 %.In figure 3 the most important energy streams are presented. It is seen that it takes about halfan hour before the energy production is reduced. The gasflow is reduced fast, but the calorificvalue of the gas remains high after the change, since pyrolysis gasses passes through the bed.In figure 4 it is seen that the height of the char bed is increased after the change and then tendsto decrease again. The reason for the increase is that the total reactivity of the char bed isreduced fast, but it takes about half an hour before the mass flow of char from the pyrolysisunit has reached the new lower value.

N2H2

CO2

CO

CH40

10

20

30

40

50

03 : 0 0 0 5 : 0 0 0 7 : 0 0 0 9 : 0 0 1 1 : 0 0 1 3 : 0 0 1 5 : 0 0 1 7 : 0 0

t im e [ h o u r : m in ]

gas

com

posi

tion

[Vol

%]

33

Figure 3. Energy flows. Before and afterchange to half load.

Figure 4. Bed height and degree of charconversion. The char conversion rate isdefined as the ratio between conversion rateand the feed rate of char to the gasifier.

6. DISCUSSION AND CONCLUSIONS

A dynamic model has been developed, describing the behaviour of the system, when the differentsubsystems interact in the two-stage gasifier. The model is verified by comparing withmeasurements obtained from a demonstration plant during operation. Likewise a simulation withthe model shows the transient behaviour of the system when changing from full to half load. Whenthe input is reduced to half load, the power and heat production a stationary level within half anhour.

REFERENCES

1.Henriksen, U. and O. Christensen (1995). Gasification of Straw in a Two-stage 50 kW Gasifier,Proceeding, 8th Eur. Biomass Conf. Pergamon, pp. 1568-1578.

2.Bentzen, J. D. and B. Gøbel (1995). Dynamisk model af totrinsforgasnings-processen (PE 95-13),(in danish), Department. of Energy Engineering, Technical University of Denmark.3. Incropera, F. P and D. P. DeWitt (1990). Introduction to heat transfer, Wiley.

4.Henriksen, et. al. (1991). Pyrolyse og forgasning af halm, Delrapport 4,(in danish), Dept. of Energy Engineering, Technical University of Denmark.

5.Stoltze, et. al. (1994). Gasification of straw in a large-sample TGA, Part 2, Nordic seminar onbiomass gasification and combustion, (Trondheim, Norway).

6.Houbak, N. (1987). SIL - a Simulation Language, User´s Guide, Lecture Notesin Computer Science, ed. by G. Goos and J. Hartmanis, Springer-Verlag, Berlin.

�� �� ������ ������� � ������� � �

� � � � � � � � � � � ��������� !#"$&%('*)

+ ,-./ 01243567 89

:�";@%A"CBD$FEHGI�I"CJ

KL�CMNG@=?>D%A"DBD$#EHGO�P"CJ

Q��I"��M�'*'��PJR>D$RG

S "TIBU>D%A"CBD$FEHGWVXM�'

1,00

1,05

1,10

1,15

1,20

1,25

1,30

0 1 2 3 4 5 6 7 8 9 10Time [hours]

Bed

hei

ght [

m]

50

60

70

80

90

100

110

Cha

r co

nver

sion

rat

e [%

]

Bed height

Char conversion

34

35

APPENDIKS 4

KONVEKTION

36

Konvektion

Varmeoverføring ved tvungen konvektion i fixed bed

(Transport Phenomena, § 13.4; Bird, Stewart & Lightfood, 1960)

Varmestrøm ved konvektion er en kompliceret funktion af overfladens geometri ogtemperatur, fluidens temperatur og hastighed, samt fluidens termofysiske egenskaber. Denalmindelige simpli ficerede beregningsmetode er Newtons kølingslov som siger, atvarmestrømmen er proportional med temperaturforskellen mellem den strømmende fluid ogoverfladen, og overfladens areal, givet på differentiel form:

dQ h a S dz T Tloc koks gasY

( ) ( )= ⋅ ⋅ ⋅ ⋅ −

Hvor hloc er den lokale varmeoverføringskoeff icient for et tværsnit af bedden, S⋅dz er bed volumen (gas og koks) a er kokspartiklernes overflade pr. volumen bed.

På basis af en lang række eksperimenter er der udviklet følgende empiriske korrelation:jH = ⋅

−0 91 0 51, Re , ψ (Re < 50)jH = ⋅

−0 61 0 41, Re , ψ (Re >50)

Hvor jH er Colburn’s jH-faktor Re er Reynoldstallet

Disse to størrelser er defineret som følger:

jh

C G

C

kHloc

pb

p

f

=⋅

⋅⋅

Z

Z

0

23υ

Re=⋅ ⋅G

a f0

υ ψ

subskript f, betyder at størrelserne skal evalueres ved film-temperatur: Tf = ½⋅(Tkoks + Tgas)

G0 er gashastigheden i tom reaktor: GVS0

=[

Zcp er gassens varmekapacitet

J

kg K⋅

ν er kinematisk viskositet m

s

2

ψ er en faktor der korrigerer for formen af kokspartiklerne (kube: ψ = 0,71)

37

k er den termiske konduktivitet W

m K⋅

Under antagelse om at Re er mindre end 50 fås:

hc G

c

k

loc

p g

p

f

=⋅ ⋅ ⋅ ⋅

⋅

−0 91 0 51 02

3

, Re\

,,ψ

ν

Bestemmelse af de indgående variable:Vol-%

[%]molstrøm[mol/min]

Molvægt[g/mol]

massestrøm[g/min]

masse-%,Y i[%]

CO 3,0 1,7 28 47,6 3,9H2 7,9 4,4 2 8,8 0,7CO2 8,6 4,8 44 211,2 17,2H2O 52,7 29,5 18 531,2 43,3N2 26,8 15,0 28 420,0 34,2CH4 0,9 0,5 16 8,0 0,7Ialt 55,9 1226,6

Film-temperaturen vælges til Tf = 1200 K

Fysiske konstanter ved 1200 K, på basis af Incropera & De Witt:

cp[J/kg⋅K]

ν[m2/s]

k[W/m⋅K]⋅103

CO 1231 137,1 79,2H2 15370 1120 528CO2 1398 87,7 85,9H2O 2387 191,5 93,5N2 1204 158,6 75,8CH4 5332 ≈230 ≈100

Bestemmelse af specifik varmekapacitet for gassen, cp:

( )c Y c Jkg Kp i p ii

= ⋅ ≈⋅∑ , 1880

Bestemmelse af kinematisk viskositet, ν:

( )ν ν= ⋅ ≈ ⋅∑ −Y msi ii 165 106

2

38

Bestemmelse af den termiske varmekonduktivitet, k:

( )k Y k Wm Ki ii

= ⋅ ≈ ⋅⋅∑

−85 10 3

G0:

( )],

min

,

min,V C

mol

molNm

sNm

s0

559

446

160

0 02

3

3^= ⋅ =

( )_ , ,V K KK

ms

ms

12001200273

0 02 0 0933 3

= ⋅ =

GV

S

m

sm

m

s0

3

2

0 093

05

2

0 47= =

⋅

=_ ,

,,

π

hvor diameteren af reaktoren er sat til 0,50 m.

Re,

,,=

⋅ ⋅=

⋅ ⋅ ⋅=

−

G

a f

ms

mm

ms

0

6

0 47

150 165 10 0 712702

3

2ν ψ (

39

Det antages at bedden er pakket således, at halvdelen af volumenet er gas og den andenhalvdel er koks.

Med disse antagelser fås at en kokspartikel har et areal på 0,0024 m2 og et areal på 8⋅10-6 m3.Dette betyder videre at 1 m3 reaktorvolumen har et koksareal på 150 m2.

40

41

APPENDIKS 5

STRÅLING

42

StrålingI dette kapitel beskrives grundlaget for at medtage strålingen mellem koks og gas ikoksbedden.Der opstill es en strålingsbalance med basis i koksen.

1: Gasstråling2: Stråling fra koks gennem gas3: Udstråling fra koks4: Reflekteret stråling

Stråling til koksen består afstråling, udsendt af gassen,(gasstråling), og stråling somudsendes fra noget af koksen,passerer igennem gassen rammernoget andet koks. (Bkoks)Tilsvarende udstråler koksen ogsåenergi, samtidig med at noget afden indkommende strålingreflekteres (Hkoks)

(1) + (2) ⇒ Hkoks(3) + (4) ⇒ Bkoks

Disse fire strålingsled beskrives ved følgende fire ligninger:(1): ε σgas gasT⋅ ⋅

4

(2): τ ⋅ Bkoks(3): ε σkoks koksT⋅ ⋅

4

(4): ρ ⋅ H koks

(1) & (2) ⇒ H T Bkoks gas gas koks= ⋅ ⋅ + ⋅ε σ τ4 (1a)

(3) & (4) ⇒ B T Hkoks koks koks koks= ⋅ ⋅ + ⋅ε σ τ4 (3a)

Energibevarelse:(5): aQ H Bkoks koks koks= −(6): a aQ Qgas koks= −

hvor εgas og ε koks er emissiviteter for hhv. gas og koksτ er andelen af udstrålingen fra koksen, som passerer igennem gassen

43

ρ er andelen af indstrålingen på koksen som reflekteres

På basis af de fire fremkomne ligninger(1a): H T Bkoks gas gas koks= ⋅ ⋅ + ⋅ε σ τ

4

(3a): B T Hkoks koks koks koks= ⋅ ⋅ + ⋅ε σ ρ4 ⇔ H

B Tkoks

koks koks koks=− ⋅ ⋅ε σ

ρ

4

⇒ ε σ τε σ

ρgas gas kokskoks koks koksT B

B T⋅ ⋅ + ⋅ =

− ⋅ ⋅44

⇒ ( )B T Tkoks koks koks gas gasτ ε ρ σ ε σρ− = − ⋅ ⋅ + ⋅ ⋅

1 4 4

⇒ BT T

koks

kokskoks gas gas

=⋅ ⋅ + ⋅

−

σε

ρε

τρ

4 4

1 (7)

(1a) & (5):H T Bkoks gas gas koks= ⋅ ⋅ + ⋅ε σ τ

4

bQ H Bkoks koks koks= −⇒

bQ H B T B Bkoks koks koks gas gas koks koks= − = ⋅ ⋅ + ⋅ −ε σ τ

4

Indsætter (7):

⇒ ( )c

Q T

T T

koks gas gas

kokskoks gas gas

= ⋅ ⋅ + − ⋅⋅ ⋅ + ⋅

−ε σ τ

σε

ρε

τρ4

4 4

11 (8)

benytter:ρ ε= −1 koksτ ε= −1 gas

44

Bestemmelse af emissiviteterne for koks, εεkoks, og gas, εεgas

εεkoks:εkoks = 0,77 - 0,95(carbon, grafit; Incropera & De Witt, 1990, s. 682)

εεgas:Til at beregne gasstrålingen benyttes Hottel's metode, der baserer sig på empiriske metoder,hvor der tages hensyn til partialtrykkene af de to gasser, CO2 og H2O, der stråler. Samtidig harformen og tykkelsen af gaslommen også betydning. Til at bestemme dette tages derudgangspunkt i en middel strålings længde, "Mean beam lengths", Le.

For en vilkårlig geometri anvendes følgende udtryk for Mean beam lengths, Le

LV

Ae=

⋅36,(Incropera & De Witt, 1990, s. 788)

Antages hulrummet mellem partiklerne at være kugleformet:

V rkugle = ⋅ ⋅4

33π

A rkugle = ⋅ ⋅42π

⇒ =V

A

r

3 (hvis A stiger bliver A/V mindre!)

Konsekvensen af dette er, at hvis man bevæger sig væk fra det ideelle, kugleformede hulrum,vil V/A-forholdet stige, hvilket igen betyder at Le øges

Med antagelsen om et kugleformet hulrum mellem kokspartiklerne, bestemmes εgas medudgangspunkt i forholdene i toppen af bedden. I denne zone af koksbedden, findes de højestetemperaturer, de største partikler og de højeste partialtryk af H2O og CO2.På basis af målinger fra forsøg med 100 kW-anlægget lægges følgende forhold til grund forbestemmelse af εgas:

T K= 1400 , p p atmH O w2 052= = , , p atmCO2 0 09= , og radius, r = 1 cm.

Bestemmelse af Le med r = 1cm:

Lr

re = ⋅ = ⋅36 312, ,

r = 1cm ⇒ Le = 1,2 cm ≈ 0,04 ft.

45

Bestemmelse af ε H O2 ved aflæsning i figur 13.16, Incropera & De Witt, 1990p L atm ft ft atm T Kw e g w H O⋅ = ⋅ = ⋅ = ⇒ = =052 0 04 0 021 1400 0 0092, , , ; ,ε ε

46

Bestemmelse af εCO2 ved aflæsning i figur 13.18, Incropera & De Witt, 1990p L atm ft ft atmCO e CO2 20 09 0 04 0 004 0 01⋅ = ⋅ = ⋅ ⇒ =, , , ,ε

∆ε:Når H2O og CO2 optræder samtidig som det er til fældet her, skal der kompenseres forvekselvirkningen mellem disse to gasser. Dette gøres ved at indføre et korrektionsled, ∆ε, derligeledes bestemmes ved aflæsning på empirisk baserede grafer. Således bestemmes gassenstotale emissivitet ved:ε ε εgas H O CO= + −2 2 ∆εhvor ∆ε aflæses i figur 13.20, Incropera & De Witt, 1990

47

( )L p pe H O CO⋅ + =2 2 0 024, , pp pWW CO+ = + =2052

052 0 09085

,

, ,,

⇒ ∆ε = 0,000⇒ εgas = εw + εCO2 - ∆ε = 0,009 + 0,01 - 0,000⇒ εgas = 0,019

Det vil sige at den total emissivitet for gassen er bestem til at være εgas = 0,019.

Parameteranalyse

Variation: Le øges med en faktor 8 fra Le = 0,04 ft. til Le = 0,3 ft. Dette svarer til at behandlemeget store koksstykker eller at hulrummet er langt fra kugleformen.

Le = 0,3 ft. = 10 cm⇒ Pw ⋅ Le = 0,16⇒ εw = 0,05 (aflæsning i figur 13.16)

⇒ PCO2 ⋅ Le = 0,03⇒ εCO2 = 0,04 (aflæsning i figur 13.18)

Le(pw + pCO2) = 0,18

48

p

p pw

w CO+=

2

085,

⇒ ∆ε = 0,00 (aflæsning i figur 13.20)

⇒ εgas = 0,09

Det ses hermed at en øgning af Le med en faktor 8, blot betyder at εgas øges med en faktor 2.

Temperatur:Sænkes temperaturen 200 °C fra 1400 K til 1200 K, betyder dette at εgas stiger fra εgas = 0,019til εgas = 0,024.

H2O-koncentrationen:Sænkes pH O2 fra p atmH O2 052= , til p atmH O2 0 40= , medfører dette at εgas falder fra εgas ≈0,019 til εgas ≈ 0,018.

CO2-koncentrationen:Hæves pCO2 fra p atmCO2 0 09= , til p atmCO2 015= , medfører dette at εgas stiger fra εgas ≈ 0,019til εgas ≈ 0,024.

49

APPENDIKS 6

ANALYTISK LØSNING AFWATER-GAS SHIFT LIGNINGEN

50

Løsning af water-gas shift reaktionen

Indgangsbetingelser:

d Ligevægtskonstanten, Ka(T), bestemmesd Bestemmelse af grundstofbalance for de indgående komponenter nC, nH og nOd

n n n nC CO ind CO ind C omsat= + +, , ,2d n n nH H O ind H ind= ⋅ + ⋅2 22 2, ,d n n n nO CO ind CO ind H O ind= + ⋅ +, , ,2 2 2

hvor, n n n nCO ind CO ind H O ind H, , ,, , ,2 2 2 er mængden af de er molstrømmene af hhtv CO,

CO2, H2O og H2 til det aktuelle kontrolvolumen. Molstrømmen af CH4 er ikkemedtaget, da den ikke indgår i water-gas shift reaktionen. nC,omsat er mængden koks deromsættes fra fast form til gasform i kontrolvolumenet.

Der skal løses et system, bestående af f ire ligninger og fire ubekendte (gasligevægt ogmassebevarelse):

1. ( )K Tn n

n naH O CO

H CO

=⋅

⋅2

2 2

2. n n nC CO CO= + 23. n n nH H O H= ⋅ + ⋅2 22 24. n n n nO CO CO H O= + ⋅ +2 2 2

Restriktioner på water-gas shift reaktionen:

i) ( ) ( ) [ ]K T T T T C Ca = ⋅ ⋅ + ⋅ ⋅ − > ∈ ° °− −1303 10 717 10 13006 0 700 12506 4, , , , ;ii ) nC > 0iii ) nH > 0iv) nO > 0

v) n n nn

C O CH< < ⋅ +2

2, da

1) der dannes frit kulstof, hvis nC > nO, hvilket udtrykket ikke tager hensyn til .2) da nC højst kan aftage nO svarende til 2*nC og nH højst kan aftage nO

svarende til nH/2

vi) nn

COO

2 2<

da der højst kan dannes halvt så mange mol CO2 som der er mol O.

Løsning af ligningssystemet:d isolering af nCO i li gning 2:

51

e 2a) n n nCO C CO= − 2e

indsættelse af ligning 2a i li gning 4:e 4a) n n n n nO C CO CO H O= − + ⋅ +2 2 22e

isolering af nH2O i li gning 4a og sammentrækning:e 4b) n n n nH O O C CO2 2= − −e

isolering af nH2 i li gning 3:

e 3a) n

nnH

HH O2 22

= −e

indsættelse af ligning 4b i li gning 3a:

e 3b) n

nn n nH

HO C CO2 22

= − + +

Opsummering:

1) ( )K Tn n

n naH O CO

H CO

=⋅

⋅2

2 2

2a) n n nCO C CO= − 2

3b) nn

n n nHH

O C CO2 22= − + +

4b) n n n nH O O C CO2 2= − −

e Indsættelse af ligning 2a) 3b) og 4b) i l igning 1):

e 1a)

( ) ( )K

n n n n n

nn n n n

a

O C CO C CO

HO C CO CO

=− − ⋅ −

− + + ⋅

2 2

2 22e omflytning i l igning 1a:

e 1b) ( ) ( )n n n n n K n n n n nO C CO C CO a H O C CO CO− − ⋅ − = ⋅ − + + ⋅2 2 2 22

e udregning af parenteserne i l igning 1b):e

2b):

( )n n n n n n n n n n n n K n n n n nO C O CO C C C CO CO C CO CO a CO H O C CO⋅ − ⋅ − ⋅ + ⋅ − ⋅ + ⋅ = ⋅ ⋅ − + + 2 2 2 2 2 2 22e

udtrykker ligning 2b på formen: 0 12

2 3= ⋅ + ⋅ +k X k X k , hvor X nCO= 2 :

e 2c) ( ) ( ) ( )0 1

22 22

= − ⋅ + ⋅ − ⋅ + ⋅ + ⋅ + ⋅ −K n K

nK n K n n n n n na CO a

Ha O a C O CO C C O

e ( )k Ka1 1= −e

k Kn

K n K n naH

a O a C O2 2= ⋅ − ⋅ + ⋅ +

e ( )k n n nC C O3 = ⋅ −

52

Løsning af systemet:

2a) n n nCO C CO= − 2

3b) nn

n n nHH

O C CO2 22= − + +

4b) n n n nH O O C CO2 2= − −

2c) ( ) ( ) ( )0 122 2

2

= − ⋅ + ⋅ − ⋅ + ⋅ + ⋅ + ⋅ −K n K

nK n K n n n n n na CO a

Ha O a C O CO C C O

2c) løses:

nk D

kCO22

12=

− +⋅

eller nk D

kCO22

12=

− −⋅

, hvor D k k k= − ⋅ ⋅22

1 34

Der er 2 mulige løsninger til nCO2 .

I det følgende udledes, at det kun er løsningen:

nk D

kCO22

12=

− +⋅

der giver gyldige løsninger til det aktuelle ligningssystem:

For Ka > 1:f ( )k K a1 1 0= − > (nævner i li gning 2c)f − + >k D2 0 (da nævneren er pos. skal tælleren også være positiv, restriktion v):

f Da D k k k= − ⋅ ⋅2

21 34

k1 er pos. og k3 er neg. (restriktion v)f D k> 2

For at tælleren skal være positiv, kan kun ”+”-tegnet gælde.

For Ka < 1:f ( )k K a1 1 0= − <

Omskrivning af ligning 2c giver:

f

( )( )n

Kn

n n K D

KCO

aH

C O a

a2

21

2 1=

− ⋅ + + ⋅ −

±

⋅ −

53

g ( )n

K

K

nn n K

K

D

KCO

a

a

HC

O a

a a2 1

22 2

1

1 2 1= −

−⋅

++

−−

±⋅ −

g ( )n

n K

K

nn D

KCOO a

a

HC

a2 2 1

22 2 1

= −−

⋅+

±⋅ −

g

K

Ka

a − 1< 0 for alle Ka < 1,

nnH C2

2

+> 0 (restriktion ii og iii )

g ( )

D

K a2 1⋅ − < 0 for alle Ka < 1

nCO2 kan derfor beskrives som:

nn

konst konstCOO

2 21 2= − ± (konst1 < 0 og konst2 < 0)

Restriktion v giver:

nn

COO

2 2< . Da konst1 er negativ og konst2 er negativ, kan kun ”+” -tegnet gælde:

For Ka = 1 fås ved indsætning i l igning 2c:

( )n

n n nn

nCO

C C O

HC

2

2

=⋅ −

+

Hermed er nCO2 bestemt som funktion af indgangsbetingelserne.

Dernæst bestemmes nCO , nH2 og nH O2 ved indsættelse af nCO2 i li gning 2a, 3b og 4b):

2a) n n nCO C CO= − 2

3b) nn

n n nHH

O C CO2 22= − + +

4b) n n n nH O O C CO2 2= − −

nk D

kCO22

12=

− +⋅

h ( )k Ka1 1= −h

k Kn

K n K n naH

a O a C O2 2= ⋅ − ⋅ + ⋅ +

h ( )k n n nC C O3 = ⋅ −

54

55

APPENDIKS 7

ENTALPI-BESTEMMELSEPÅ BASIS AF KNACKE

(Knacke et. al., 1991)

56

Entalpi-bestemmelse på basis af KnackeI modellen af pyrolyse- og forgasningsprocessen benyttes entalpierne for de indgående

komponenter som funktion af temperaturen. I dette bilag bliver disse udtryk for entalpienbestemt på baggrund af tabelopslag i [Knacke et. al., 1991], herefter betegnet: ”Knacke”.Tabelværdierne bliver tilnærmet med poynomier af 3. eller 4. grad og bliver ill ustreret grafisksammen med de tilhørende polynomier i de følgende diagrammer. Til sidst bringes tabellerover værdierne sammen formeludtryk for datafittene.

Der er bestemt udtryk for grafit (C), CH4, CO, CO2 , H2, H2O, N2 og O2.

Grafit

0

5000

10000

15000

20000

25000

30000

300 500 700 900 1100 1300 1500

Temperatur [K]

Spe

cifik

ent

alpi

[J/m

ol]

Knacke

Datafit til Knacke

CH4

-75000

-65000

-55000

-45000

-35000

-25000

-15000

-5000

5000

15000

300 500 700 900 1100 1300 1500

Temperatur [K]

Spe

cifik

ent

alpi

[J/m

ol]

Knacke

Datafit til Knacke

57

CO

-115000

-110000

-105000

-100000

-95000

-90000

-85000

-80000

-75000

-70000

-65000300 500 700 900 1100 1300 1500

Temperatur [K]

Spe

cifik

ent

alpi

[J/m

ol]

Knacke

Datafit til Knacke

CO2

-400000

-390000

-380000

-370000

-360000

-350000

-340000

-330000

-320000300 500 700 900 1100 1300 1500

Temperatur [K]

Spe

cifik

ent

alpi

[J/m

ol]

Knacke

Datafit til Knacke

H2

0

5000

10000

15000

20000

25000

30000

35000

40000

300 500 700 900 1100 1300 1500

Temperatur [K]

Spe

cifik

ent

alpi

[J/m

ol]

Knacke

Datafit til Knacke

58

H20

-245000

-235000

-225000

-215000

-205000

-195000

-185000

300 500 700 900 1100 1300 1500

Temperatur [K]

Spe

cifik

ent

alpi

[J/m

ol]

Knacke

Datafit til Knacke

N2

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

300 500 700 900 1100 1300 1500

Temperatur [K]

Spe

cifik

ent

alpi

[J/m

ol]

Knacke

Datafit til Knacke

O2

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

300 500 700 900 1100 1300 1500

Temperatur [K]

Spe

cifik

ent

alpi

[J/m

ol]

Knacke

Datafit til Knacke

59

Grafit TKelvin Celsius Knacke Datafit til Knacke

298 25 0 -4300 27 15 14400 127 1053 1058500 227 2389 2394600 327 3966 3968700 427 5737 5736800 527 7663 7656900 627 9706 9694

1000 727 11829 118221100 827 13998 140171200 927 16251 162621300 1027 18547 185461400 1127 20875 208651500 1227 23231 232201600 1327 25610 25617

i, , , , ,h E T E T E T TC = − ⋅ − − ⋅ + − ⋅ − ⋅ −24682 9 13146 5 27950 2 46904 75965

4 3 2

CH4 TKelvin Celsius Knacke Datafit til Knacke

298 25 -74872 -74865300 27 -74807 -74796400 127 -71005 -71021500 227 -66621 -66635600 327 -61668 -61673700 427 -56173 -56170800 527 -50169 -50160900 627 -43687 -43679

1000 727 -36765 -367591100 827 -29438 -294371200 927 -21741 -217451300 1027 -13712 -137201400 1127 -5386 -53951500 1227 3199 31951600 1327 12008 12016

j, , , ,h E T E T TCH4

3 257518 6 37413 2 136969 821173= − − ⋅ + − ⋅ + ⋅ −

60

CO TKelvin Celsius Knacke Datafit til Knacke

298 25 -110528 -110550300 27 -110475 -110490400 127 -107527 -107493500 227 -104462 -104434600 327 -101325 -101316700 427 -98137 -98145800 527 -94908 -94925900 627 -91643 -91662

1000 727 -88347 -883601100 827 -85020 -850231200 927 -81664 -816571300 1027 -78281 -782661400 1127 -74871 -748851500 1227 -71435 -714281600 1327 -67972 -67991

k, , , ,h E T E T TCO = − − ⋅ + − ⋅ + ⋅ −78966 7 40847 3 274025 1190574

3 2

CO2 TKelvin Celsius Knacke Datafit til Knacke

298 25 -393521 -393625300 27 -393455 -393542400 127 -389413 -389239500 227 -384838 -384692600 327 -379974 -379927700 427 -374927 -374968800 527 -369749 -369839900 627 -364469 -364566

1000 727 -359104 -3591731100 827 -353666 -3536841200 927 -348162 -3481241300 1027 -342597 -3425181400 1127 -336976 -3368901500 1227 -331299 -3312651600 1327 -325571 -325668

l, , ,h E T E T TCO2

3 241037 6 17087 2 325902 404746= − − ⋅ + − ⋅ + ⋅ −

61

H2 TKelvin Celsius Knacke Datafit til Knacke

298 25 0 4300 27 53 62400 127 2954 2943500 227 5856 5846600 327 8776 8773700 427 11723 11725800 527 14698 14704900 627 17706 17712

1000 727 20746 207511100 827 23821 238221200 927 26929 269261300 1027 30072 300671400 1127 33250 332441500 1227 36463 364611600 1327 39712 39718

m, , ,h E T E T TH2

3 22 8541 7 7 5371 4 281799 8468= − ⋅ + − ⋅ + ⋅ −

H2O TKelvin Celsius Knacke Datafit til Knacke

298 25 -241856 -241887300 27 -241796 -241820400 127 -238437 -238386500 227 -234857 -234815600 327 -231130 -231116700 427 -227283 -227295800 527 -223333 -223359900 627 -219287 -219316

1000 727 -215152 -2151721100 827 -210929 -2109341200 927 -206622 -2066111300 1027 -202232 -2022081400 1127 -197759 -1977341500 1227 -193204 -1931941600 1327 -188569 -188597

m, , , ,h E T E T TH O2

3 211853 6 8 2233 3 290266 2512363= − − ⋅ + − ⋅ + ⋅ −

62

N2 TKelvin Celsius Knacke Datafit til Knacke

298 25 0 -19300 27 52 39400 127 2984 3013500 227 6021 6045600 327 9123 9131700 427 12274 12267800 527 15464 15449900 627 18689 18673

1000 727 21946 219351100 827 25233 252301200 927 28549 285561300 1027 31894 319071400 1127 35266 352801500 1227 38665 386711600 1327 42091 42075

n, , , ,h E T E T TN2

3 26 7373 7 37142 3 273867 84926= − − ⋅ + − ⋅ + ⋅ −

O2 TKelvin Celsius Knacke Datafit til Knacke

298 25 0 -16300 27 53 44400 127 3029 3052500 227 6123 6142600 327 9303 9309700 427 12552 12547800 527 15863 15852900 627 19230 19218

1000 727 22649 226401100 827 26115 261131200 927 29627 296321300 1027 33181 331911400 1127 36775 367861500 1227 40407 404121600 1327 44075 44062

n, , , ,h E T E T TO2

3 285894 7 51249 3 268116 84378= − − ⋅ + − ⋅ + ⋅ −

63

APPENDIKS 8

ELEMENTARANALYSEAF

STANDARD GASIFIER FUEL(SGF)

64

65

66

67

APPENDIKS 9

FUGTPROCENT I FLIS

68

Fugtprocent i fli s

Forsøget skulle køres med tørt fli s for at sikre fuld pyrolysering i pyrolyseenheden. Flisen, derblev købt hos Junckers Industrier, havde ved leveringen et fugtindhold på 32 %. Forud forforsøget blev fli sen tørret ved gennemblæsning.

Flisen lå i et ca. 1 meter tykt lag på en perforeret bund i en container. I flere dage blev derblæst luft gennem flisen. Dette resulterede i et varierende fugtindhold i fli sen gennemforsøget.

Fugtighedsmålinger i flisen under forsøgskørsel i uge 37, 1998

0.0%

5.0%

10.0%

15.0%

20.0%

25.0%

30.0%

35.0%

07/09/98 12:00 08/09/98 00:00 08/09/98 12:00 09/09/98 00:00 09/09/98 12:00 10/09/98 00:00 10/09/98 12:00 11/09/98 00:00

fugt-%

totalt gennemsnit:

Serie3

Der blev jævntligt udtaget fli sprøver til fugtighedsbestemmelse. Serie 3 er fugtmålinger treforskelli ge steder i fli scontaineren: I midten og i de to ender. De øvrige målinger er taget veden blanding af det øverste fli s.

69

APPENDIKS 10

TØMNING AF KOKSBED EFTER UGE 37

70

Tømning af koksbed efter uge 37 - forsøgUdført mandag den 28. oktober 1998af: Benny Gøbel og Freddy Christensen

Start:målt højden af koksbeden gennem skueglas i toppen af reaktoren.lodret mål:• centrum: 181,5 cm• kant af skueglas: 185 cmEfter tømningen er afstanden fra skueglas til risten målt til 276 cm.⇒ Bedhøjden er:• centrum: 276 cm - 181,5 cm = 94,5 cm• kant af skueglas: 276 cm - 185 cm = 91 cm

Visuel inspektion fra toppen:Bedden danner en kegle med top i centrum. Vinkel: max 30° (vurderet, usikkert).

Under rist:Da dækslet for mandehullet blev fjernet, fandt vi at hele rummet under risten var fyldt medkoks.Dette blev udtaget med støvsuger.Bund 1: 8218 gBund 2: 6718 g

Udtager lag 1(prøve 1, kokslaget på risten): 417 g

Udtager lag 2:100 slag med risten, benytter knappen på styretavlen: 1171 gHøjde herefter: 187 cm ⇒ Bedhøjden er 276 - 187 = 89 cm:

Udtager lag 3:Sætter sug på mandehullet, vha. støvsugeren. Målt undertryk: ml. 30 - 55 mm H2O100 slag med risten, benytter knappen på styretavlen: 3328 gHøjde herefter: 206 cm ⇒ Bedhøjden er 276 - 206 = 70 cm:

Udtager lag 4:prøve 2: 127 g

Udtager lag 5:10 slag til en side, med fuldt udslagHøjde herefter: 206 cm ⇒ Bedhøjden er 276 - 224 = 52 cm:10 slag til begge sider, med fuldt udslag

71

Højde herefter: 251 cm ⇒ Bedhøjden er 276 - 251 = 25 cm:

Udtager prøve 3:

Udtager lag 5, fortsat:10 slag til begge sider, med fuldt udslag: lag 5, ialt: 9418 gHøjde herefter: 276 cm ⇒ Bedhøjden er 276 - 276 = 0 cm:

Totalt:Under rist: 8218 + 6718 = 14.936 gOver rist: 417+1171+3328+127+9418 = 14.461 g

På basis heraf kan koksens gennemsnitli ge massefylde bestemmes:

tværsnitsareal, A = 0,1963 m2

højde, h = 0,93 mmasse, m = 14,9 kg

⇒ massefylde, ρ = 81,6 kg/m3

72

73

APPENDIKS 11

DYNAMISK MODEL AF KOKSBEDDENVERSION 1

BENYTTET VED SAMMENLIGNING MEDSGF-FORSØG

74

$TITLE= forgasning af koks(* model, der beskriver forgasningen af biomassekoks. *)

BEGIN

(* declarations *)

PARAMETER Q_tab(0), m_koks_in(6.39), (* mol/min *) cp_koks(14.76), (* [J/(mol*K)] *) CO_in(1.32), (* mol/min *) H2_in(3.51), (* mol/min *) CO2_in(5.30), (* mol/min *) H2O_in(28.41), (* mol/min *) N2_in(16.05), (* mol/min *) CH4_in(0.30), (* mol/min *)

(* Reaktivitets-konstanter *) A(1.5e9), E(2e5), n1(0.602844), n2(7.05305), p1(1e26), m1(-8), R(8.314), (* gaskonstanten *) c_ideal(44.62), (* antal mol pr Nm3 idealgas *)

rho_koks(81.6), (* kg/m3 *) mol_mas_koks(12e-3),(* kg/mol *) A_bed(0.1963), (* m2 *)

(* Brændværdibestemmelse *) n_b_CO(283e3), n_b_H2(241.9e3), n_b_CH4(802.5e3), oe_b_CO(283e3), oe_b_H2(285.9e3), oe_b_CH4(890.5e3);

VARIABLE T_in, M_KOKS01(7.52372E+0000), M_KOKS02(8.42756E+0000), M_KOKS03(9.44737E+0000), M_KOKS04(1.05999E+0001), M_KOKS05(1.19046E+0001), M_KOKS06(1.33840E+0001), M_KOKS07(1.50644E+0001), M_KOKS08(1.69766E+0001), M_KOKS09(1.91564E+0001), M_KOKS10(2.16459E+0001), M_KOKS11(2.44945E+0001), M_KOKS12(2.77602E+0001), M_KOKS13(3.15115E+0001), M_KOKS14(3.58291E+0001), M_KOKS15(4.08087E+0001), M_KOKS16(4.65638E+0001), M_KOKS17(5.32289E+0001), M_KOKS18(6.09646E+0001), M_KOKS19(6.99622E+0001), M_KOKS20(8.04503E+0001), M_KOKS21(9.27029E+0001), M_KOKS22(1.07048E+0002), M_KOKS23(1.23882E+0002), M_KOKS24(1.43679E+0002), T01 (1.28772E+0003), T02 (1.27593E+0003), T03 (1.26414E+0003), T04 (1.25233E+0003), T05 (1.24052E+0003), T06 (1.22870E+0003), T07 (1.21688E+0003), T08 (1.20506E+0003), T09 (1.19324E+0003), T10 (1.18142E+0003), T11 (1.16961E+0003), T12 (1.15782E+0003), T13 (1.14603E+0003), T14 (1.13426E+0003), T15 (1.12251E+0003), T16 (1.11077E+0003), T17 (1.09907E+0003), T18 (1.08739E+0003), T19 (1.07574E+0003), T20 (1.06413E+0003), T21 (1.05256E+0003), T22 (1.04104E+0003), T23 (1.02956E+0003), T24 (1.01814E+0003), m_koks_ud01, m_koks_ud02, m_koks_ud03, m_koks_ud04,

75

m_koks_ud05, m_koks_ud06, m_koks_ud07, m_koks_ud08, m_koks_ud09, m_koks_ud10, m_koks_ud11, m_koks_ud12, m_koks_ud13, m_koks_ud14, m_koks_ud15, m_koks_ud16, m_koks_ud17, m_koks_ud18, m_koks_ud19, m_koks_ud20, m_koks_ud21, m_koks_ud22, m_koks_ud23, m_koks_ud24, R01(), R02(), R03(), R04(), R05(), R06(), R07(), R08(), R09(), R10(), R11(), R12(), R13(), R14(), R15(), R16(), R17(), R18(), R19(), R20(), R21(), R22(), R23(), R24(), C_omsat01(0.1), C_omsat02(0.1), C_omsat03(0.1), C_omsat04(0.1), C_omsat05(0.1), C_omsat06(0.1), C_omsat07(0.1), C_omsat08(0.1), C_omsat09(0.1), C_omsat10(0.1), C_omsat11(0.1), C_omsat12(0.1), C_omsat13(0.1), C_omsat14(0.1), C_omsat15(0.1), C_omsat16(0.1), C_omsat17(0.1), C_omsat18(0.1), C_omsat19(0.1), C_omsat20(0.1), C_omsat21(0.1), C_omsat22(0.1), C_omsat23(0.1), C_omsat24(0.1), Ka01, Ka02, Ka03, Ka04, Ka05, Ka06, Ka07, Ka08, Ka09, Ka10, Ka11, Ka12, Ka13, Ka14, Ka15, Ka16, Ka17, Ka18, Ka19, Ka20, Ka21, Ka22, Ka23, Ka24, CO_01(), CO_02(), CO_03(), CO_04(), CO_05(), CO_06(), CO_07(), CO_08(), CO_09(), CO_10(), CO_11(), CO_12(), CO_13(), CO_14(), CO_15(), CO_16(), CO_17(), CO_18(), CO_19(), CO_20(), CO_21(), CO_22(), CO_23(), CO_24(), H2_01(), H2_02(), H2_03(), H2_04(), H2_05(), H2_06(), H2_07(), H2_08(), H2_09(), H2_10(), H2_11(), H2_12(), H2_13(), H2_14(), H2_15(), H2_16(), H2_17(), H2_18(), H2_19(), H2_20(), H2_21(), H2_22(), H2_23(), H2_24(), H2O_01(), H2O_02(), H2O_03(), H2O_04(), H2O_05(), H2O_06(), H2O_07(), H2O_08(), H2O_09(), H2O_10(), H2O_11(), H2O_12(), H2O_13(), H2O_14(), H2O_15(), H2O_16(), H2O_17(), H2O_18(), H2O_19(), H2O_20(), H2O_21(), H2O_22(), H2O_23(), H2O_24(), CO2_01(), CO2_02(), CO2_03(), CO2_04(), CO2_05(), CO2_06(), CO2_07(), CO2_08(), CO2_09(), CO2_10(), CO2_11(), CO2_12(), CO2_13(), CO2_14(), CO2_15(), CO2_16(), CO2_17(), CO2_18(), CO2_19(), CO2_20(), CO2_21(), CO2_22(), CO2_23(), CO2_24(),

(* Energibevarelse *) (* IND *) H_koks_in, H_H2_in, H_CO_in, H_CO2_in, H_H2O_in, H_N2_in, H_CH4_in, Q_in,

(* UD *) (* specifik entalpi for koks *) hh_koks01, hh_koks02, hh_koks03, hh_koks04, hh_koks05, hh_koks06, hh_koks07, hh_koks08, hh_koks09, hh_koks10, hh_koks11, hh_koks12, hh_koks13, hh_koks14, hh_koks15, hh_koks16, hh_koks17, hh_koks18, hh_koks19, hh_koks20, hh_koks21, hh_koks22, hh_koks23, hh_koks24, H_koks01, H_koks02, H_koks03, H_koks04, H_koks05, H_koks06, H_koks07, H_koks08, H_koks09, H_koks10, H_koks11, H_koks12, H_koks13, H_koks14, H_koks15, H_koks16, H_koks17, H_koks18, H_koks19, H_koks20, H_koks21, H_koks22, H_koks23, H_koks24, H_H2_01, H_H2_02, H_H2_03, H_H2_04, H_H2_05, H_H2_06, H_H2_07, H_H2_08, H_H2_09, H_H2_10, H_H2_11, H_H2_12, H_H2_13, H_H2_14, H_H2_15, H_H2_16, H_H2_17, H_H2_18, H_H2_19, H_H2_20, H_H2_21, H_H2_22, H_H2_23, H_H2_24,

76

H_CO_01, H_CO_02, H_CO_03, H_CO_04, H_CO_05, H_CO_06, H_CO_07, H_CO_08, H_CO_09, H_CO_10, H_CO_11, H_CO_12, H_CO_13, H_CO_14, H_CO_15, H_CO_16, H_CO_17, H_CO_18, H_CO_19, H_CO_20, H_CO_21, H_CO_22, H_CO_23, H_CO_24, H_CO2_01, H_CO2_02, H_CO2_03, H_CO2_04, H_CO2_05, H_CO2_06, H_CO2_07, H_CO2_08, H_CO2_09, H_CO2_10, H_CO2_11, H_CO2_12, H_CO2_13, H_CO2_14, H_CO2_15, H_CO2_16, H_CO2_17, H_CO2_18, H_CO2_19, H_CO2_20, H_CO2_21, H_CO2_22, H_CO2_23, H_CO2_24, H_H2O_01, H_H2O_02, H_H2O_03, H_H2O_04, H_H2O_05, H_H2O_06, H_H2O_07, H_H2O_08, H_H2O_09, H_H2O_10, H_H2O_11, H_H2O_12, H_H2O