The Institute of Gas Technology has been developing the PEATGAS process for the conversion of peat to synthetic fuels. A program has recently been completed for the pilot-plant-scale testing of the process. In this scheme, peat is gasified in a two-stage reactor system, which operates at temperatures up to 1750/sup 0/F and pressures up to 500 psig. The process can be controlled to maximize the production of either substitute natural gas (SNG) or liquid hydrocarbons. The technical feasibility of the process was demonstrated in a series of five gasification tests. Highlights of this operating program are presented in this paper

Biljetina, R.

Punwani, D.

UNT Digital Library

INSTITUTE OF GAS TECHNOLOGY PEAT GAS^ PILOT-PLANT OPERATING RESULTS -------- /--- R. Biljetina D. Punwani Paper Presented at IECEC CONFERENCE Los Angeles, California August 8-13, 1982 3424 S0UTJ-I STATE STREET IIT CENTER I - CHICAGO. ILLINOIS GC16'lB EDUCATION - RESEARCH 1' AFFILIATED WITH ILLINOIS INITITUTE OF TECHNLJLOCY !: - .d DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. , :. . . ";:-:-,!;;f&;i :- R. B i l j e t ina  and D,. Punwani !. . . ,, , $ - i  - - * t , . :  ;.. - . ,J . . d ri ,-qy,. v . I n s t i t u t e  of Gas Technology . I * d.. -3 r Abstract . - +- A h  r'- The I n s t i t u t e  of Gas Technology has been . I * W U I D  ,am"W.fR -. _. developing the  PEATGW process f o r  t he  conversion ..*R" of peat t o  synthet ic  fue ls .  A program has recently been completed for  t h e  pilot-plant-scale t e s t i n g  of t h e  process. In t h i s  scheme, peat is gas i f ied  i n  a two-stage reac tor  system, which operates a t  temper- a tures  up t o  1750°F and pressures up t o  500 psig.  The process can be controlled t o  maximize t h e  pro- duction of e i t h e r  subs t i t u t e  na tu ra l  gas (SNG) o r  .- . O.IOl,d --*-(* WI~I l i qu id  hydrocarbons. The technical  f e a s i b i l i t y  of t h e  process was demonstrated in  a s e r i e s  of f i v e  gas i f ica t ion  t e s t s .  Highlights of t h i s  operating Figure 1. SIMPLIFIED FLOW DIAGRAM OF program a r e  presented i n  t h i s  paper. THE PEATGAS PROCESS - I, i n s t a l l ed  because peat required more drying and 8 - screening capacity and less grinding capacity than BACKGROUND was avai lable  i n  the  exis t ing  plant .  A s lur ry ing method was used t o  i n j e c t  peat i n t o  the  g a s i f i e r  North America has s igni f icant  peat deposits ,  f o r  t he  i n i t i a l  tests. Sowever, when the  lock- vhich a r e  estimated t o  contain an equivalent of hoppers were in s t a l l ed  f o r  the  l a t e r  t e s t s ,  more i over 380 b i l l i o n  ba r re l s  of o i l .  These deposits  - y  - 2, I a r e  generally located i n  areas tha t  have no other 4 s ign i f i can t  f o s s i l  f u e l  resources. The I n s t i t u t e  of Gas Technology (IGT) has been conducting research on peat u t i l i z a t i o n  s ince  1974. Its goal has been t o  develop a process f o r  the  production of synthet ic  fue ls .  This work was f i r s t  i n i t i a t e d  by Minnesota Gas Co. (Minnegasco). Since 1974 sponsorship has expanded t o  include the  U.S. Department of Energy . (DOE), Gas Research I n s t i t u t e  (GRI), and InterNorth (a  parent company of Northern Natural Gas Co.). Hundreds of laboratory and process development uni t  (PDU) t e s t s  were performed (1-9) during the  l a s t  7 years t o  evaluate peat a s  a feedstock f o r  synthet ic  f u e l  production. Not only has t h i s  work shown tha t  on the  bas i s  of its chemistry and .' k ine t i c s  peat is  an excellent  raw mater ia l  f o r  the  h production of subs t i t u t e  na tura l  gas, but i t  has a l s o  resulted in the  development o f  t h e  PEATGAS process (Figure 1). PROCESS DESCRIPTION To fur ther  advance the  PEATGAS process concept, large-scale p i l o t  plant  s tud ie s  were s t a r t e d  l a s t  year i n  an exis t ing  coal  gas i f ica t ion  f a c i l i t y  [Figi~re 2) a t  IGT'e Energy Development Center (E) I n  Chicago. Only minor modifications of t he  gasif-  i@r were requrved t o  provide the  necessary config- urat ion f o r  the  PJZATGAS processing scheme. New drying, screening and crwhing equipment was ale0 Figure 2. YEATGAS PILOT PLANT FACILITY AT THE IGT ,, . ,  ENERGY DEVELOPMWT CENTER I N  CHICAGO I N S T I T U T E  I 0 F G A S .  T E C H N O L O G Y  v a r i a b i l i t y  was achieved i n  some of the  key gasif- i e r  operating parameters, resul t ing i n  more econ- omically favorable operating conditions. The modified plant i s  capable of converting a nominal 50 tons of dry peat i n t o  0.5 million stand- ard cubic f ee t  of subs t i tu te  natura l  gas daily. The basic features  of the  p i l o t  plant are  - Peat Preparation In the  newly ins ta l l ed  peat preparation section (Figure 3) .  as-received peat containing 60 I#- t o  75 weight percent water is dried i n  a natural-  gas-fired, triple-pass rotary drum dryer. Up t o  XREENEW / ' LOCIUOPPERS PRODUCI OE Figure 3. PEAT PREPARATION SECTION 16 tons of wet, raw peat per hour can be dried t o  a moisture level  as low as  10 weight percent. The dried peat is  then screened t o  a -20+80 U.S.S. mesh s i z e  product. Product peat is conveyed t o  the  lockhopper feed system f o r  in ject ion i n t o  the  b-- - ,  gasi f ier .  Oversize material  is crushed in  a hammer m i l l  and returned t o  the  screeners. Two 200-ton s i l o s  a r e  availab* fo r  intermediate storage of prepared peat. Peat Lockhopper Feed Inject ion The new lockhopper feed system (Figure 4) is  capable of providing a continuous, measured flow of 1 t o  4 tons of dry peat per hour t o  the  gas i f i e r  a t  pressures up t o  500 psig. The system includes a 17-ton bin that  provides surge capacity .during operation, a scalping screen tha t  prevents foreign objects from entering the lockhoppers and possible bridging i n  the in jectors  or lodging i n  the c r i t i c a l  lockhopper valves, a storage in jector  tha t  cycles i n  pressure and adds a known quantity of peat a t  regular in tervals  t o  the  primary in jector  and the  primary in jector  tha t  is  always a t  system pressure and meters out a constant feed r a t e  of peat. Both in jector  vessels r e s t  on load ce l l s ,  which a r e  separated by a balanced pressure expan- sion jo in t  i n  order t o  accurately measure the peat fed t o  the  gas i f ier .  PEAT TO GASIFIER r VENT INJECTOR INJECTOR TRANSPORT Figure 4. PEAT LOCIuIOPPER FEED INJECTION Gasification Solids a r e  injected a t  the top of the PEATGAS reactor (Figure 5) where the transport nitrogen is disengaged and hot gases r i s ing  through a fluidized bed from the lower sections of the reactor vaporize theomoisturo i n  the peat and preheat the sol ids  t o  450 F. The peat so l ids  then overflow by gravity from t h i s  drying zone in to  the f i r s t  reaction stage, the  hydrogasifier (HG). RAW PROWCT OAS TO WENCH DRYING ZONE FIRST-STAGE HVOROGASFICATION SECONDSTAGE TO L W  OIL - CHAR GISFICATION RECOVm SYSTEM ASH TO FILTRATION & WATER TREATMENT Figure 5. GASIFICATION SECTION T E C H N O L O G Y  In  t h e  HG, which opera tes  a t  1000' t o  1400°F, second, t o  conduct peat g a s i f i c a t i o n  t e s t s .  These both the  v o l a t i l e  matter  and t h e  more r e a c t i v e  p a r t  t a s k s  were success fu l ly  completed during a  2-year of t h e  peat a r e  converted t o  methane and o ther  program period.  Key program da tes  were - l i g h t  hydrocarbons i n  a  shor t  residence time zone . . by reac t ion  with t h e  hydrogen-rich gas produced i n  t h e  lower s t a g e  of t h e  r e a c t o r .  O i l s  r e leased  i n  Contract Awarded - I n i t i a t e d  Design t h i s  g a s i f i c a t i o n  s t a g e  account f o r  10% t o  30% of of  Feed Preparation And Lockhopper System . Apri l  1980 the gasified depending On the temperature in I n s t a l l a t i o n  o f  Feed Preparation Equipment Sept.  1980 - Peb. 1981 t h e  HG. So l ids  from t h e  hydrogas i f ie r  overflow by grav i ty  t o  t h e  next s t a g e ,  t h e  char  g a s i f i e r  (CG): Equipment Shakedown . Uarch 1981 In  t h e  CG, the  unreacted char  is  exposed t o  a  temperature of about 1700°F i n  a  dense-phase f l u i d i z e d  bed. Steam and oxygen a r e  i n j e c t e d  i n t o  t h e  bottom through a  three-nozzle d i s t r i b u t o r .  . These gases se rve  a s  t h e  f l u i d i z i n g  medium f o r  t h e  char  and provide r e a c t a n t s  f o r  combustion and steam/ carbon r e a c t i o n s .  The char  res idue ,  now over 90% gas i f ied .  i s  discharged from t h e  r e a c t o r ,  quenched, s l u r r i e d  with water and depressurized.  The char  res idue  is  recovered i n  downstream f i l t r a t i o n  and separa t ion  equipment. Product Gas Quench and O i l  Recovery In  t h e  product gas quench and o i l  recovery s e c t i o n  of t h e  plant  (Figure 6 ) ,  t h e  product gas  leaving t h e  g a s i f i e r  a t  450°F is  cooled t o  100°F by d i r e c t  water quench, which condenses t h e  steam and l i g h t  o i l .  Af te r  an oi l -water  s e p a r a t i o n ,  t h e  l i g h t  o i l  is  withdrawn, depressurized and s t o r e d .  The water is reused i n  t h e  quench system. The p i l o t  p lan t  f a c i l i t y  a l s o  con ta ins  gas p u r i f i c a t i o n  and methanation s e c t i o n s  where CO and H S a r e  removed before c a t a l y t i c  methanation o$ t h e  2  remaining carbon monoxide and hydrogen. These u n i t s  remained on standby during t h e  peat g a s i f i c a -  t i o n  t e s t s .  OUENCHEDPRODUCTGAS r To ACID GAS REMOVAL TOWER 1 RAW OIUWATER I SEPARATOR PREOUENCH TOWER 1 I-. CONDENSATE TO WATER TREATMENT OIL RE%VERY SYSTEM VENT h PRODUCT OIL S1ORAUt' TANK Reactor Flow Test  Three G a s i f i c a t i o n  T e s t s  - Slurry Fred (PT-1. PT-2 and PT-3) Received Approval t o  I n s t a l l  Lockhoppers Lockhopper I n s t a l l a t i o n  c Equipment Shakedown Tvc G a s i f i c a t i o n  T e s t s  - Lockhopper Feed (PT-L and PT-5) Apr i l  1981 June - Aug. 1981 August 1981 Sept .  - Nov. 1981 Dec. 1981 Jan. - Uarch 1982 After  completing t h e  shakedown of t h e  new feed prepara t ion  equipment (drying,  screening and crushing)  i n  March 1981, t e s t i n g  was begun i n  t h e  p i l o t  p l a n t .  The e x i s t i n g  s l u r r y  system was used t o  i n j e c t  peat i n t o  t h e  g a s i f i e r  because t h e  lock- hopper system was scheduled t o  be i n s t a l l e d  l a t e r  i n  t h e  year .  The f i r s t  t e s t ,  completed i n  Apr i l  1981, was conducted mainly t o  ob ta in  sol.ids flow da ta  with t h e  PEATGAS g a s i f i e r  conf igura t ion  dur ing  i n t e g r a t e d  opera t ion  of t h e  t e s t  f a c i l i t y .  Oxygen was not added t o  t h e  char  g a s i f i c a t i o n  zone. Af te r  success fu l ly  completing t h e  s o l i d s  flow t e s t ,  a  s e r i e s  of t h r e e  g a s i f i c a t i o n  t e s t s  (PT-1, -2 and -3) were conducted i n  June, Ju ly  and August 1981. The main ob jec t ives  of t h e  g a s i f i c a t i o n  t e s t s  were t o  ob ta in  opera t ing  experience with Minnesota pea t  and t o  s tudy t h e  e f f e c t  of g a s i f i e r  steam p a r t i a l  p ressure ,  temperature and peat  feed r a t e  on product y i e l d s  and composition. The lock-  hopper system was e rec ted  a f t e r  t h i s  s e r i e s  of t e s t s .  The cons t ruc t ion  period was acce le ra ted  i n  o rder  t o  devote t h e  remaining opera t ing  program t o  t e s t s  using t h e  dry feed mechanism. Two success fu l  g a s i f i c a t i o n  t e s t s  (PT-4 and -5) were then con- ducted,  expanding t h e  d a t a  base t o  lower steam-to- feed carbon r a t i o s  i n  t h e  g a s i f i e r  and h igher  pea t  feed moisture con ten ts .  These represen t  more econ- omically favorable  opera t ing  condit ions.  Table 1 h i g h l i g h t s  t e s t  condi t ions  f o r  t h e  f i v e  g a s i f i c -  a t i o n  t e s t s .  A t y p i c a l  peat  sc reen  and chemica l ' ana lys i s  is given i n  Table 2. Typical  gas composition and o i l  b o i l i n g  point  Figure 6. PRODUCT GAS QUENCH AND OIL 'RECOVERY d i s t r i b u t i o n  f o r  a  hydrogas i f ie r  temperature of slOOO°F, a  char  g a s i f i e r  temperature of 1650°F and GASIFICATION TEST PROGRAM a  steam-to-carbon r a t i o  of 1.1 a r e  given i n  Tables 3  a n d ' 4 ,  respec t ive ly .  The o v e r a l l  program had two main o b j e c t i v e s : ,  f i r s t .  t o  modify t h e  e x i s t i n g  p i l o t  p lan t  f o r  peat  . processing inc lud ing  i n s t a l l a t i o n  of t h e  drying,  , screening,  gr inding and lockhopper feed systems and I N S T I T U T ' E  T E - C H N O L O G Y  . ' Table  1. GASIFICATION TEST OVERVIEW Test PT-I - PT-2 - .  PT- 3 -Month June July August , Pressure, psig 500 500 500 Peat Fed to Gasifier, tons 30 100 ' 100 Peat Feed Rate Ury, tonslhr 0.5-1.0 1.0-1.5 0.5-1.75 Moisture. ut 2 5-10 5-10 5-10 Hydrogasifier Temp (Wax). O F  910-960 1060-1140 1060-1190 t * .  PT-4 PI-5 Jan. March 300 500 150 200 1.0-2.0 1.0-2.0 10-20 15-30 9LO-1080 910-990 Char Gasifier Temp (Max). O F  1050-1200 1450-1550 . 1500-1650 1650-1725 1550-1675 SreamlCarbon Ratio. molar 3.9-5.9 2.6-6.2 1.8-5.4 1.0-2.1 1.5-2.7 OxygenlCarbnn Ratio. molar -- 0.13-0.21 0.17-0.30 0.12-0.18 0.11-0.18 Peat Conversion (Y&) ,  7. 73-74 89-98 91-99 92-98 85-94 + ?re:iminary data. Table  3.  TYPICAL PRODUCT GAS ANALYSIS Table  2. TYPICAL MINNESOTA PEAT SCREEN AND CHEMICAL ANALYSIS Screen A n a l y s i s ,  U.S. S.,  wt% +10 0.0  +4 0 +60 +80 + l o o  +200 -200 T o t a l  Bulk Dens i ty ,  l b / f t 3  Mois tu re ,  wt % Chemical Ana lys i s  Proximate ,  wt % Mois tu re  V o l a t i l e  Mat t e r  Fixed Carbon Ash T o t a l  IJ l t jmate  (Dry) ,  wt X Carbon Hydrogen S u l f u r  * Composition (Dry),  mol % Hydrogen 38.0 Carbon Monoxide . 16.4 Methane 10.4 Carbon Dioxide 34.9 Ethane 0 .3  Hydrogen S u l f i d e  -- - T o t a l  100.0 * Nitrogen- and o i l - f r e e .  Typ ica l  f eed  carbon d i s t r i b u t i o n  is 65-75 w i  % t o  t h e  gas ,  20-30 wt % t o  t h e  l i g h t  o i l  and 5 t o  I 1 0  wt % t o  t h e  ash.  Opera t ion  o f  t h e  h y d r o g a s i f i e r  zone a t  h i g h e r  t empera tu res  (>1250°F) w i l l  r e s u l t  i n  h i g h e r  methane p roduc t ion  and lower o i l  y i e l d s .  The o i l  composi t ion,  however, w i l l  s h i f t  t o  lower  b o i l i n g  po in t  f r a c t i o n s ,  which a r e  a more d e s i r a b l e  g a s o l i n e  b lend ing  feedst0c.k.  Table  4. TYPICAL OIL BOILING POINT DISTRIBUTION Ni t rogen  2.2 Oxygen (by D i f f e r e n c e )  27.0 CONCLUSlUN Ash 17 .3  T o t a l  100.0 The s u c c e s s f u l  p i l o t  p l a n t  program r e s u l t e d  i n  a n  e x t e n s i v e  d a t a  base .  A range of o p e r a t i n g  c o n d i t i o n s  were covered t o  s tudy  t h e  e f f e c t  of I N S T I T U T E  T E C H N O L O G Y  major gasifier parameters on product yield and composition. These included - Char Gasifier Temperature, OF 1450-1725 'Hydrogasifier Temperature, OF 910-1190 Steam/Carbon Feed Ratios, molar 1.0-5.9 Peat Feed Rate, tonslhr 0.5-2.0 Peat Moisture Content, wt % 5-30 Peat Conversion, (MAF) % 73-99 The technical feasibility of the PEATGAS process has been demonstrated on a pilot plant scale. The data obtained represent a significant data base for scale-up to commercial operation. Additional data are desirable at steamlcarbon ratios of 0.7 and higher hydrogasifier temperatures (up to 1400°F), which will maximize the production of methane in the gasifier and improve oil quality. These data would further improve the economics of the PEATGAS process. The experience gained, to date, has shown that peat is highly reactive and an excellent feed material for hydrogasification to substitute natural gas. ACKNOWLEDGMENT The work presented in this paper was jointly funded by the U.S. Department of Energy and the Gas Research Institute. REFERENCES 1. Institute of Gas- Technology, "Experimental Program for the Development of Peat Gasifica- tion." Interim R~E. No. 3: Coiled Tube Reactor Experiments, DOE Rep. No, FE-2469-17. Springfield, Va., January 1978. 2. Punwani, D.V., Nandi, S.P. and Johnson, J.L.. "Peat Gasification - An Experimental Study." Paper presented at the 85th National Meeting of the American Institute of Chemical Engineers, Philadelphia, June 4-8, 1978. 3. Institute of Gas Technology, "Experimental Program for the Development of Peat Gasifi- cation." Interim Rep. No. 5: Hydrogasifi- cation and Fluidized-Bed Tests, DOE Rep. No. FE-2469-35. Springfield, Va., March 1979. 4. Institute of Gas Technology, "Experimental Program for the Development of Peat Gasifi- cation." Interim Rep. No. 7: Task 2. Hydrogasification Tests, Task 3. Fluidized-Bed Tests for the period October 1, 1978, through July 31, DOE Rep. No. FE-2469-48. Springfield, Va., February 1980. 5. Institute of Gas Technology, "Experimental Program for the Development of Peat Gasifi- cation." Interim Rep. No. 2: Thermobalance Studies, ERDA Rep. No. FE-2469-10. Springfield, Va.. April 1977. 6. Weil, S . A . ,  Nandi, S.P., Punwani, D.V. and Kopstein, M.J., "Peat Hydrogasification." Paper presented at the 176th National Meeting of the American Chemical Society, Miami, September 10-15. 1978. 7. Weil, S.A., Punwani, D.V.,.Kopstein, M.J. and Rader, A.M., "Kinetics of Peat Hydropyrolysis." Paper presented at the 179th National Meeting of the American Chemical Society, Houston, March 23-28, 1980. 8. U.S. Government Printing Office, Coal Conver- sion Systems Technical Data Book, ~ ~ ~ 1 ~ 2 2 8 6 - 0 1 ,  .Section lllA 51.4. Washington, D.C., 1978. 9. Punwani. D.V., Weil, S.A., Pyrcioch, E.J. and Nandi, S.P. "Peat Char Gasification - Laboratory and PDU-Scale Studies." Paper presented at IECEC, Seattle, August 18-22, 1980. I N S T I T U T E  T E C H N O L O G Y  

PEATGAS pilot plant operating results

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PEATGAS pilot plant operating results

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