Fro rom m sy syng nga as to me meth tha ano noll an d dime di mett hy hyll et he her r Ferru rrucci ccio o Trif Trifiro iro`` Sum ummer mer Sch choo ooll Sept pte emb mbe er 2009 Bologna
Con onte tent nt of th the e le lect ctur ure e • 1) Synth Synthes esis is of meth methan anol ol from from sy syng ngas as • 2) Synth Synthes esis is of of dim dimet ethy hyle leth ther er (DME (DME)) fro from m methanol • 3) Synth Synthes esis is of DME DME dir direc ectl tly y fro from m syn synga gas s
Glob loba al produ pr oducti ction on of of methanol • The The glob global al produc productio tion n of of meth methano anoll is about about 40 million million ton per year, most of which is produced from natural gas. Today, the high price of oil and natural gas has spurred new interest in alternative feedstocks for the production of methanol. • Vari Variou ous s type types s of of biom biomas ass s hav have e bee been n con consi side dere red, d, but but on on the shorter term coal appears to be the only viable alternative raw material for large scale methanol production. • In fac fact, metha thanol nol ha has be been prod produ uced ced fro from m • coal coal for for man many y year years s in spec specifi ific c geog geogra raph phic ical al are areas as,, notably in China.
Fro rom m me m et ha hano noll to t o fue f uels ls • 1) Metha Methano noll to to DME DME (alte (altern rnati ative ve to Dies Diesel el)) • 2) Metha ethano noll for for fuel fuel cell ell • 3) Meth Methan anol ol for for pro produ duct ctio ion n of of MTB MTBE E • 4) Meth Methan anol ol as as fue fuell (al (alte tena nati tive ves s to to gasoline) • 5) Metha Methano noll for for prod produc ucti tion on of hydr hydrog ogen en • 6) Synt Synthe hesi sis s of gaso gasoliline ne (MTG (MTG proc proces ess) s)
Fro rom m me m eth tha ano noll to t o che c hemi mica cals ls chloromethanes
Formaldehyde
Di-methylterephthalate
Methanol Methyl formiate
Methyl amines
Acetic Acid
Methyl methacrylate
Fr o m m me et h an o l t o t o olefins • The The diffe differe rent nt tech techno nolo logi gies es for for the the futu future re SDTO DME
SYNGAS CH3OH From Methane Coal Municipal Municip al wastes wastes Recycl Recycle ed pl astics Biomass Organic
OLEFINS MTO MTP PROPYLENE
Syn yntt he hesi sis s of o f me m eth tha ano noll • CO+2H2
CH3OH ΔH298k=-90.6kJmol-1
• Metha Methano noll sy synt nthe hesi sis s is the the seco second nd larg larges estt process after ammonia which use catalysts at high pressure • The The mech mechan anis ism m is beli believ eved ed to be • CO+H2O-> CO2+H2
ΔH298k=-41.2kJmol-1
• CO2+2H2->CH3OH+H2O ΔH298k= -49kJmol-1
Ope pera rati tive ve co cond ndit itio ions ns fo forr meth me tha ano noll syn s ynth the esi sis s • Catalyst : CuO(6 CuO(60-7 0-70%) 0%)-- ZnO(20 ZnO(20-30 -30%) %) –Al2O3 (515%)or Cr 2O3 (5-15%) • Temp 220oC-300oC • Pressure 50-100Atm (5-10MPa) • Composi omp ositio tion n of the fee feed 59 -74%H2 27- 15% CO 8% C02 3%CH4 • Conversion of CO to methanol per pass is normally 16– 40 %. • H2 : CO ratio of 2.17. • The selecti selectivi vity ty is around 99.8 %
Com omm m er c i al Tec h no noll og ogie ies s • Toda Today y ther there e are are four four catal catalys ystt supp supplie liers rs and and six companies complete proprietary processes for methanol synthesis : ICI, Lurgi, Topsøe, Mitsubishi, M.W. Kellogg and Uhde. • Desi Design gn figu figure res s for for conv conver erter ters s can can be as high as 2,500-10,000 tonnes for day • A goo good cata atalyst lyst in a natu atural ral gasgas-ba bas sed plant may over its lifetime of about 4 years
Ways to impr im prov ove e th the e yi yie eld in methanol 1) The rea reactio ct ion n is i s exothermi exot hermic c and favore favor ed at low tempera temperatur ture e, for this rea reason is necess necessa ary to remove remov e the th e heat heat to t o ke k eep the t he rea reaction cti on tempera temperatur ture e as low as possib pos sible le in orde ord er to t o increa in crease se the conve conv ersion rsi on 2) To re r emove mov e methanol methanol duri d uring ng the synthesis syn thesis in order order to shift the equilibrium quili brium to higher higher CO CO to methanol methanol conversio co nversion n per per pass (thr (throug ough h the th e DME formatio for mation) n) 3) To de d evelop mor m ore e activ ct ive e cataly catalyst sts s whi w hich ch ope op erate at lower lo wer temperatur temperature e, incr in cre easing si ng the th e thermodyna thermody namic mica ally allo allowe wed d conve conv ersion rsi on
Equi quili libri brium um CO con conve versi rsion on to meth me tha ano noll (H2/CO=2) Conversion 11 CO
50bar
0,5
400
I s o t h e r m a l 450
CO +2H2->CH3OH
100 bar
adiabatic 500
550
600
K Temperature
The fa facto ctors rs affe ffecti cting ng on the productio produc tion n The factors affecting on the production rate in an industrial methanol reactor are: 1)the 1)the thermody thermodyna namic mic equilibri quil ibrium um limita limi tations tions 2) The cataly catalyst st de d eactiv ct iva ation ti on.. Two zones could be distinguished in the methanol synthesis reactor with imprecise transition point. A) A )The first firs t zone starts from reactor entrance and continues to a point that conversion approaches to equilibrium. In this zone the kinetics controls the process, so increasing temperature improves the rate of reaction which leads to more methanol production. B) In the th e secon second d zone the process switches to equilibrium and as the temperature increases the deteriorating effects of equilibrium equilibrium conversion emerge and decreases methanol production
Facto ctors rs whi which ch inf influe luence nce acti activi vity ty • Meth Methan anol ol syn synth thes esis is gas gas is cha chara ract cter eris ised ed by the the stoichiometric ratio (H2 – CO2) / (CO + CO2), often referred to as the module M. A module of 2 defines a stoichiometric synthesis gas for formation of methanol. • A hig high h CO to CO2 CO2 rat ratio io will will incr increa ease se the the rea react ctio ion n rate rate and the achievable per pass conversion. In addition, the formation of water will decrease, reducing the catalyst deactivation rate. •
High concentration concentration of inerts inerts will lower the partial pressure of the active reactants. Inerts in i n the methanol synthesis are typically methane, argon and nitrogen.
Met h an o l Me Meg ap l an t • The The capa capaci city ty of of metha methano noll pla plant nts s is incre increas asin ing g to reduce investments, taking advantage of the economy of scale. • The The cap capac acit ity y of of a wor world ld sc scal ale e pla plant nt has has increased from 2500 MTPD a decade ago to about 5000 MTPD today. • Even ven lar larg ger plan plants ts up to 10,0 10,000 00 MTPD MTPD or abov above e are considered to further improve economics and to provide the feedstock for the Methanol-toOlefin (MTO) process.
The ma main in se sect ctio ions ns of me meth tha ano noll plant • 1) In the first section of the plant natural gas is converted into synthesis gas. • 2) In the second section, section, the synthesis gas reacts to produce methanol • 3) In the tail-end of the plant methanol is purified to the desired purityl with eventually the hydrogen recycle • 4) utilities •
The rol ro l e o f the t he sy syng nga as production • In the the des desig ign n of of a met metha hano noll pla plant nt the the thre three e sections may be considered independently, and the technology may be selected and optimised separately for each section. • The The synt synthe hesis sis gas gas pre prepa para rati tion on and and comp compre ressi ssion on typically accounts for about 60% of the investment, and almost all energy is consumed in this process section. Therefore, the selection of reforming technology is of paramount importance, regardless of the site.
The pro produc ductio tion n of o f syn synga gas s • The The pre prefe ferr rred ed tec techn hnol olog ogie ies s are: are: • 1) tubular steam reforming • 2) two-step reforming (tubular steam reforming followed by autothermal or oxygen blown secondary reforming) • 3) Autothermal Reforming (ATR) at low steam to carbon (S/C) ratio is the preferred technology for large scale plants by maximising the single line capacity and minimising the investment.
Meth tha ano noll Sy Sy nt nthe hes s i s an an d Purification • Raw metha meth anol no l is a mixture of methanol, a small amount of water, dissolved gases, and traces of byproducts. • Typica ypic al byproduct bypr oducts s include DME, higher alcohols, other oxygenates and minor amounts of acids and aldehydes • The The met metha hano noll syn synthe thesi sis s cat catal alyst yst and and pro proces cess s are are highly highl y selectiv selective e. A selectivity of 99.8% is not uncommon.
The de des s i gn o f t h e r eac t o r • The The meth methan anol ol sy synth nthes esis is is exot exothe herm rmic ic and and the maximum conversion is obtained at low temperature and high pressure. • A cha challllen enge ge in in the the desi design gn of of a meth methan anol ol synthesis is to remove the heat of reaction efficiently and economically
BWR
Quench reactor
Multiple Adiabatic
Tube cooled
Qu en c h re r eac t o r • A quench rea reactor cto r consists of a number of adiabatic catalyst beds installed in series in one pressure shell. In practice, up to five catalyst beds have been used. The reactor feed is split into several fractions and distributed to the synthesis reactor between the individual catalyst beds. • The The que quenc nch h re reacto actorr des desig ign n is is tod today ay cons consid ider ered ed obsolete and not suitable for large capacity plants
Qu en c h re r eac t o r • Conv onvers ersion ion CO CO to to met metha hano noll Conversion CO
Temperature
Ad A d i ab abat atii c r eac eactt o r s • . • A synthesis lo loop wi with adia di abatic re r eactor ct ors s normally comprises a number (2-4) of fixed bed reactors placed in series with cooling between the reactors. The cooling may realized be by preheat of high pressure boiler feed water, generation of medium pressure steam, and/or by preheat of feed to the first reactor. • The The adi adiab abati atic c rea reacto ctorr syst system em featu feature res s good good economy of scale. Mechanical simplicity contributes to low investment cost. The design can be scaled up to single-line capacities of 10,000 MTPD or more.
Mul ulti tipl ple e la laye yers rs adi dia aba bati tic c converters • conversioCn O
• CO
N
Equilibrium curve
V E R S I O
Maximum r eaction r ate curve cur ve
N
Temperature
B WR REA REACT CTOR OR • The BWR( BWR(boil bo ilng ng water water re r eactor ct or)) is in principle a shell and tube heat exchanger with catalyst on the tube side. Cooling of the reactor is provided by circulating boiling water on the shell side. By controlling the pressure of the circulating boiling water the reaction temperature is controlled and optimised. The steam produced may be used as process steam, either direct or via a falling film saturator. • The The iso isoth ther erma mall nat natur ure e of of the the BWR BWR giv gives es a hig high h conversion compared compared to the amount of catalyst installed. However, to ensure a proper reaction rate the reactor will operate operate at intermed intermediate iate tempera temperatures tures - say between between 240ºC 240ºC and 260ºC 260ºC - and conseq consequent uently ly the recycle recycle ratio ratio may still be significant.
Equi quili libri brium um CO con conve versi rsion on to meth me tha ano noll (H2/CO=2) Conversion 11 CO
50bar
0,5
400
I s o t h e r m a l 450
CO +2H2->CH3OH
100 bar
adiabatic 500
550
600
K Temperature
Seve verr al ind i ndus ustt ri ria al pro p roc c ess sse es ICI adia di abatic bati c sin s ingl gle e bed react reactor or:: the heat of reaction is removed by adding cold reagent at different heights in the bed Lurgi two t wo multitu mul titubula bularr rea reactor: ctor : the heat of reaction is removed in the first reactor by boiling water around bed in the second reactor by gas Haldor ld or Topso op soe e severa severall adia di abatic react reactor ors: s: arranged in series intermediate cooler remove heat of reaction Ai A i r p r o d u c t -Chem -Ch em s y s t em t h r ee ph p h ase as e fl f l u i d i zed bed: reactor an inert hydrocarbon liquid inside the reactor remove the heat Casale isothermal reactor: the heat is removed by plates immersed in the catalysts
Lurgi Mega Methanol plant • Lurg Lurgi‘i‘s s Meg Mega a Met Metha hano noll proc proces ess s is is an an advanced technology for converting natural gas to methanol at low cost in large quantities. • It perm permits its the the con const stru ruct ctio ion n of high highly ly efficient single-train plants of at least double the capacity of those built to date.
The MegaMethanol Concept The Lurgi Lurgi MegaMe MegaMethan thanol® ol® technol technology ogy has been been developed for world-scale methanol plants with capacities greater than one million metric tons per year. The main process features to achieve these targets are: ■1) Oxygen-blown natural gas reforming, either in combination with steam reforming, or as pure autothermal reforming. 2)Two-step methanol methanol synthesis synthesis in in waterwater- and gas■ 2)Two-step cooled reactors operating along the optimum reaction route. ■ 3) Adjustment of syngas composition by hydrogen recycle.
Lurgi reactor
Lurg Lu rgii re r eact ctor or Mai n fe f eat ure ur es The Lurgi reactor is nearly isothermal and the heat of reaction is used to generate high pressure steam which is used to drive the compressor and as distillation steam Ad A d v ant an t ages ag es Optimum temperature profile Very high gas synthesis conversion Large reduction of catalyst volume Lower gas recycle High energy efficiency
Lurgi rea reactor- conve conversion rsion versus ve rsus te tempe mpera rature ture
The sy synt nthe hesi sis s gas gas prod pr oduc ucti tion on The synthesis gas production section accounts for 60 %of the capital cost of a methanol plant. Thus, optimisation of this section yields a significant cost benefit. Conventional steam reforming is economically applied in small and medium-sized methanol plants, with the maximum single-train capacity being limited to about 3000 mtpd. Oxygen-blown natural gas reforming, either in combination with steam reforming or as pure autothermal reforming, is today considered to be the best suited technology for large syngas plants. The configuration of the reforming process mainly depends on the feedstock composition which may vary from light natural gas (nearly 100% methane content) to oiloilassociated gases.
Lurg Lu rgii aut autot othe herm rma al conve con vers rsio ion n Light Natural gas desulphurization
Steam reforming
Autothermal reforming •.
Methanol synthesis
Methanol distillate PURE METHANOL
Air Air separation
Process steam
oxygen
Au A u t o t h er erm m al Ref Refo orming Pure autothermal reforming can be applied for syngas production whenever light natural gas is available as feedstock to the process. The desulfurised and optionally pre-reformed feedstock is reformed with steam to synthesis gas at about 40 bar and higher using oxygen as reforming agent. The process generates a carbon-free synthesis gas and offers great operating flexibility over a wide range to meet specific requirements. Reformer outlet temperatures are typically in the range o 950–1050 °C.
Lurgi combi combine ned d re reformi forming ng Heavy natural gas or oil desulphurization
Air
Air separation
Pre reforming
Autothermal reforming •.
oxygen FUEL GAS
Methanol synthesis
Methanol distillate PURE METHANOL
Hydrogen recovery
Lurg Lu rgii Com ombi bine ned d Refo form rmin ing g For heavy natural gases and oil-associated gases, the required stoichiometric number cannot be obtained by pure autothermal reforming, even if all hydrogen available is recycled. For these applications, the Lurgi MegaMethanol® MegaMethanol® concept combines autothermal and steam reforming as the most economic way to generate synthesis gas for methanol plants. After desulfurisation, a feed gas branch stream is decomposed in a steam reformer at high pressure(35–40 bar) and relatively low temperature (700–800°C).The reformed gas is then mixed with the remainder of the feed gas and reformed to syngas at high pressure in the autothermal reactor. This concept has become known as the Lurgi Combined Reforming Process.
The du dua al Lur L urgi gi re rea act cto o rs Based on the Lurgi Methanol Reactor and the highly active methanol catalyst with its capability to operate at high space velocities, Lurgi has has recently recently developed developed a dual reactor reactor system featuring higher efficiency. The isothermal reactor is combined in series with a gas-cooled reactor The first reactor, the isothermal reactor, accomplishes partial conversion of the syngas to methanol at higher space velocities and higher temperatures compared with single stage synthesis reactors. This results in a significant size reduction of the water-cooled reactor compared to conventional processes, processes, while the steam raised is available at a higher pressure. .
Lurg Lu rgii Mega Mega Re React ctor ors s
Lurgi rea reactor- conve conversion rsion versus ve rsus te tempe mpera rature ture
Wat er c o o l ed r eac t o r
Gas co c o o l ed re r eac t o r
Fir irs s t re r eact ctor or fo forr Me Meth tha ano noll Synthesis The Lurgi Methanol Reactor is basically a vertical shell and tube heat exchanger with fixed tube sheets. The catalyst is accommodated in tubes and rests on a bed of inert material.The water/steam mixture generated by the heat ofreaction is drawn off below the upper tube sheet. Steam pressure control permits exact control of the reaction temperature.This isothermal reactor achieves very high yields at low recycle ratios and minimizes the production of by-products.
Seco cond nd rea react ctor or fo forr me meth tha ano noll synthesis The methanol-containing methanol-containing gas leaving the first reactor is routed to a second downstream reactor without prior cooling. In this reactor, cold feedgas for the first reactor is routed through tubes in a countercurrent flow with the reacting gas. Thus, the reaction temperature is continuously reduced over the reaction path in the second reactor, and the equilibrium driving force for methanol synthesis maintained over the entire catalyst bed. As fresh synthesis synthesis gas is only fed to the first reactor, no no catalyst poisons reach the second reactor. The poisonfree operation operation and the low operating temperature result in a virtually unlimited catalyst service life for the gascooled reactor.
Ad A d v an antt ag ages es o f t h e Com Co m b i n ed Sy Syn n t h es esii s Converters High syngas conversion efficiency. At the same conversion efficiency, the recycle ratio is about half of the ratio in a single-stage, water-cooled reactor. reactor. ■ High energy efficiency. About 0.8 t of 50–60 bar steam per ton of methanol can be generated in the reactor. In addition, a substantial part of the sensible heat can be recovered at the gas-cooled reactor outlet. ■ Low investment cost. The reduction in the catalyst volume for the water-cooled reactor, the omission of the large feedgas preheater and savings resulting from other equipment due to the lower recycle ratio translate into specific cost savings of about 40% for the synthesis loop. ■ High single-train capacity. Single-train plants with capacities of 5000 mt/day and above can be built. ■
Meth tha ano noll Dis Disti till la lati tion on The crude methanol is purified in an energy-saving 3-co 3-colu lumn mn dist distililla lati tion on unit unit with with the the 3-co 3-colu lumn mn arrangement, the higher boiling boiling componen componentsare tsare separated separated in in two pure methanol columns. The first pure methanol column operates at elevate elevated d pressur pressure e and theseco thesecond nd column column at atmo atmosp sphe heri ric c pres pressu sure re.. The The over overhe head ad vapo vapour urs s of the pressurised column heat the sump of theatm theatmosp ospher heric ic column. column. Thus, Thus, about about 40% of the heating heatingstea steam m and, and, in turn, turn, about about 40% 40% of the the cooling capacity aresaved. The split of the refining column into two columns allows for very high single-train capacities.
L u r g i Pla lan nt
ICI Reactor
cold
Qu en c h re r eac t o r • Conv onvers ersion ion CO CO to to met metha hano noll Conversion CO
Temperature
ICI p r o c es s
ICI
TOPSOE REACTORS
methanol methano l
Con onve vers rsio ion n ve vers rsus us te temp mpe era ratu ture re
Topso opsoe e Metha thanol nol Proce Process ss • Base Based d on the the uni uniqu que e meth methan anol ol cata cataly lyst st,, MK-1 MK-121 21,, Hald Haldor or Topsøe has developed a methanol synthesis process. the heart of the synthesis unit is the methanol reactor, a tubular reactor with catalyst loaded into several tubes surrounded by a bath of boiling water. The boiling water efficiently cools the process while at the same time steam is produced that can be used outside the methanol synthesis unit. The design of the reactor ensures that the methanol synthesis is carried out at an almost isothermal reaction path at conditions close to the maximum rate of reaction. This ensures a high conversion per pass and a low formation of by-products.
Top opsø søe e's me m eth tha ano noll syn s ynth the esi sis s c at al y s t MK -121 . Based on an optimised copper dispersion MK-121 ensures a better preservation of the initial high catalyst activity as well as an improved stability compared to its predecessor, MK-101, while at the same time attaining a remarkable selectivity. resulting in low by-product formation over the entire service life. Since the higher activity of MK-121 allows operation at lower temperatures, where conditions for by-product formation is less favourable, the total .
To p s o e Cat al y s t MK 121
To p s o e c at al y s t MK 121
Cata taly lyst st Lo Loa ad in ing g The procedure used for catalyst loading is extremely important, as the catalyst performance depends heavily on even flow distribution. Therefore, the catalyst should be loaded as uniformly as possible to ensure that the catalyst is utilised efficiently. Besides that, the catalyst should be packed as densely as possible in order to maximise the installed catalyst activity. Topsøe has developed new loading methods, which increase loading density of the catalyst and improve the flow distribution through the catalyst bed(s) in various types of methanol converter designs. Furthermore, Topsøe is continuously studying existing loading procedures in order to develop new innovative techniques for installing catalyst.
Fluid bed reactor from Air products
Aii r p r o d u c t Ch A Chem em s y s t em • Main features • Dem Demonst onstra rati tio on pla plan nt in in Tex Texa as • The The cata cataly lyst st is is susp suspen ende ded d in ine inert rt hyd hydro roca carb rbon on liq liqui uid d which limits the temperature rise and it adsorbs the heat liberated • Advantages • a hig highe herr sin singl gle e pas pass s con conve vers rsio ion n can can be achi achiev eved ed reducing the syngas compression costs • inc increas rease e of life life of cataly talyst st • Cont Contai ains ns low low amou amount nt o wate waterr 1% (the (the gas gas phas phase e 4-20 4-20% % of water • It is is poss possib ible le to to work work wit with h 50% 50% CO ente enteri ring ng fee feeds dsto tock cks s
Cas al e Reac t o r • The The use use of axial axial-r -rad adia iall flo flow,e w,e,, can can solve solve the problem, of reducing the pressure drop of a converter. This design can be obtained easily with the use of plates as cooling surface area, The flow of cooling gas inside the plates can have the same direction of the gas in the catalyst, that is in a horizontal direction, cocurrent or counter-current (see figure) • It is cle clear ar that that an axia axiall rad radia iall des desig ign n lead leads s to a much slimmer vessel for the same catalyst volume, allowing to reach capacities above 7’000 MTD in a single vessel converter.
Ax A x i al r ad adii al p l at ate e co c o o l ed r eac eactt o r
Ax A x i al r ad adii al c at atal aly y s t b ed
Met h an o l Cas al e rea reac t o r s At present more than 10 million tons per per year of methanol methanol are produced worldwide with Methanol Casale technolog technologies ies • Methanol Methanol Casale’s Casale’s synthesis synthesis converte converterr technology allows substantial and cost-effective capacity increases in conventional methanol plants • Methanol Methanol Casale Casale is currently currently licensing licensing,, providing providing basic design and supplying critical equipment for a 7,000 t/d methanol plant • A 7,000 7,000 t/d plant plant can be built built based based on a single single methanol methanol converter. They are the only contractors able to build real single train, efficient plants with this t his capacity •
Cas al e an d t h e r ev am p i n g o f meth me tha ano noll pl pla ant •
.
• , Meth Methan anol ol Casa Casale le has has als also o bec becom ome e a lead leader er in revamping complete methanol plants and in designing and constructing new ones. Key achievements in plant upgrading include capacity increase, reduced specific consumption of synthesis gas, and improvement in the quality of the raw methanol. • They re revamped 21 21 ICI ICI plants
Lind Li nde e re rea act ctor or • The The Lind Linde e iso isothe therma rmall reac reactor tor is a fixe fixed d bed bed reacto reactorr with with indirect heat exchange suitable for endothermic and exothermic catalytic reactions. This reactor provides the benefits of a tube reactor while simultaneously avoiding the heat tension problems of a straight tube reactor. Gas/gas, gas/liquid and liquid/liquid reactions can be carried out. The palpable head of gases and liquids as well as the latent evaporation heat can be used for cooling or heating operations. • The The heat heatin ing g or cool coolin ing g tube tube bun bundl dle e embe embedd dded ed in in the the catalyst transfers the reaction heat in such a way that the catalyst can work at an optimum temperature. This results in higher outputs, a longer catalyst lifetime, fewer by-products as well as efficient recovery of the reaction heat and lower reaction costs.
Lind Li nde e re rea act ctor or • Lind Linde e isot isothe herm rmal al reac reactor tor,, cro cross ss-se -secti ction on with with catalyst and tube bundle • The The dev devel elop opme ment nt of of the the Lin Linde de reac reacto torr was was carried out with a particular view toward exothermic reaction and steam generation. • The The rea react ctor or is base based d on on the the desi design gn of the the specially wound heat exchangers, with which Linde has been able to collect decades of experience in its own production facilities. The Linde isothermal reactor is in operation worldwide in more than 19 plants, among them eight methanol plants.
Linde Reactor • Isothermal reactor
Section Linde reactor
Linde reactor • . The The mai main n prin princip ciple le is tha thatt the the cool coolin ing g coil coil in the the catalyst bed removes the heat of reaction allowing the catalyst to operate at it's optimum temperature. This results in higher performance, longer catalyst life, reduction of by-products, as well as in high efficiency reaction heat recovery and lower cost of the reactor. •
TOYO REACTOR
Toyo
Toyo reactor • Appli pplica cabl ble e to to 5,0 5,000 00 - 6,00 6,000 0 t/d t/d clas class s la large rge scale methanol plant with a single train design • Low Low Pre Press ssur ure e Dro Drop p thr throu ough gh Catal Catalys ystt Bed Bed and Low Utility Consumption • Mild Mild Ope Opera rati ting ng Con Condi diti tion ons s for for Long Long Catalyst Life • Main Mainte tena nabil bility ity for for cata cataly lyst st exch exchan ange ge
Toyo
TOYO REACTOR
DME i n t w o s t ep s
DME i n o n e s t ep
Fr o m me m et h an o l to t o DM DME • DME DME synt synthe hesi sis s bas based ed on metha methano noll deh dehyd ydra rati tion on process is very simple. • 2 CH3OH -> 2DME + H2O • The The deh dehyd ydra rati tion on of metha methano noll is is a gas gas pha phase se and and exothermic xo thermic rea reaction ct ion,, the heat of reaction (approx.23 kj/mol) is considerably small compared with methanol synthesis reaction. • The selecti selectivi vity ty of DME in methanol dehydration is very high and is approx. 99.9 %. • Dehydration catalyst is of gamma alumina basis
Ope pera rati tive ve co cond ndit itio ions ns fo forr DME • Feed Feed meth methan anol ol is is fed fed to a DME DME rea react ctor or after vaporization. • The The sy synt nthe hes sis pres press sure ure is 1.0 1.0 - 2.0 2.0 MPa. • The The inle inlett tem tempe perratur ature e is 220 - 250 250 °C °C and and the the out outlet let is 300 300 - 350 350 °C. °C. • Meth Methan anol ol one one pas pass s con conve vers rsio ion n to to DME DME is 70 – 85 % in in the the reac reactor tor..
DME DM E Pl Pl an antt • 1) Prod Produc uced ed DME DME with with by-p by-pro rodu duct ct wate waterr and and unconverted methanol is fed to a DME column after heat recovery and cooling. • 2) In the the DME DME col colum umn n DME DME is sep separ arat ated ed from from the top as a product. Water and methanol are discharged from the bottom and fed to a methanol column for methanol recovery. 3) The purified methanol from the column is recycled to the DME reactor after mixing with feedstock methanol. The methanol consumption for DME production is approximately 1.4 tonmethanol per ton-DME.
DME DM E PL PL A NT RAW METHANOL
METHANOL COLUMN
DME COLUMN DME REACTOR
D M E DC Mo El u m n
FUEL GAS
C H3 O H DME TANK
WATER
DME from syn- ga gas s • . The The synthe synthesis sis of DME from from syn synthe thesis sis gas involv involves es three three reactions: • 1) CO2+3 H2->CH3OH+H2O • 2)CO+H2O-> CO2+H2 • 3) 2 CH3OH ->2CH3OCH3 +H2O • The The intro introduc ductio tion n of of React Reaction ion (3), (3), the the DME DME synthe synthesis sis,, serve serves s to relieve the equilibrium constraints inherent to the methanol synthesis by transforming the methanol into DME. Moreover, the water formed in Reaction (3) is to some extent driving Reaction (2) to produce more hydrogen, which in turn will drive Reaction (1) to produce more methanol. Thus, the combination of these reactions results in a strong synergetic effect, which dramatically increases the synthesis gas conversion potential.
Fro rom m sy syng nga as to DME • The The cata cataly lyst st app applilied ed is is a pro propr prie ieta tary ry dua duall-fu func nctio tion n catalyst, catalyzing both steps (i.e., methanol and DME synthesis) in the sequential reaction. Significant advantages arise by permitting the methanol synthesis, the water–gas shift, and the DME synthesis reaction to take place simultaneously. This methanol synthesis is restricted by equilibrium, which requires high pressure in order to reach an acceptable conversion • A dua duall cat catal alys ystt sys syste tem m is is bas based ed on a com combi bina nati tio on [of Cu/ZnO/Al2O3 catalyst and gamma-alumina (this issue) catalyst.:
Dal i an Ins Insti titt ut ute e of Ch em i c al Physics • In the midmid-19 1990 90s, s, DICP DICP was was awa award rded ed two two patents in the United States concerned with the conversion of methanol/dimethyl ethe etherr (DME (DME)) to ligh lightt ole olefi fins ns.. Thes These e patents are the basis for the syngas via dimethyl ether to olefin process (SDTO).
Catalyst foDME from syngas • Bifun Bifunct ctio iona nall met metal al (Cu (Cu,, Zn, Zn, etc. etc.))-ze zeol olite ite catalysts have been developed, which can convert syngas very selectively to DME with high carbon monoxide (CO) conversion (this reaction is far more favorable thermodynamically than methanol synthesis from syngas). • . • ).
Advantages of SDTO • Syng Syngas as to DME DME bre break aks s the the therm thermod odyn ynam amic ic limi limitt of syngas to methanol system with up to over 90 percent CO conversion, 5-8 percent investment savings and 5 percent operational cost savings. • Syng Syngas as to DME DME bre break aks s the the therm thermod odyn ynam amic ic limi limitt of syngas to methanol system with up to over 90 percent CO conversion, 5-8 percent investment savings and 5 percent operational cost savings.
Sto tora rage ge and and Hand ndli ling ng of me meth tha ano noll •
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Methanol is stable under normal storage conditions. but can react violently with strong oxidizing agents. • The The gre great ates estt haz hazar ard d inv invol olve ved d in hand handliling ng meth methan anol ol is is the danger of fire or explosion.. Methanol is aggressive toward copper, zinc, magnesium, tin, lead, and aluminum, which should therefore be avoided. Similarly, the use of plastics for storage is not recommendedBoth recommendedBoth floatingfloating- and fixed-roo fixed-rooff tanks are used used for large-sca large-scale le methanol storage. • Blan Blanke keti ting ng the the tan tank k vap vapor or spac space e in in com combi bina nati tion on with with a closed vent recovery system may be required by local environmental regulations. •
