application is as a household cooki

application is as a household cooking fuel [Lucas, 2002].
In this paper, we present detailed process designs and
performance estimates for production of DME from coal,
together with cost analysis. Since there are many similarities
to methanol production, which is more widely understood,
we include self-consistent analyses of methanol
from coal for reference.
2. Basic process configurations for indirect coal
liquefaction
Figure 1 illustrates two basic process configurations for
making MeOH, DME, or Fischer-Tropsch fuels by indirect
coal liquefaction. The difference between the two is
that in one case the only output from the facility is a
liquid fuel. In the other case, electricity is a major coproduct.
The two configurations are essentially identical
through the first few process steps.
The first process step is gasification, which converts
the coal into a ‘‘synthesis gas’’ (or syngas) containing primarily
hydrogen (H2) and carbon monoxide (CO). A variety
of gasifier designs are in commercial operation
worldwide using coal or other dirty, low-value feedstocks
(e.g., petroleum coke generated at refineries) [Simbeck
and Johnson, 2001]. Here we have chosen to consider a
design based on the technology of Chevron/Texaco. This
design uses partial oxidation of the coal in oxygen (generated
in a dedicated air separation unit) to provide the
requisite heat to drive the gasification reactions. The coal
is fed into the reactor in a water slurry, which has two
important implications. Feeding can be done into a vessel
operating at relatively high pressures (75 bar in plant configurations
considered in this paper), which provide thermodynamic
and cost benefits to the overall process, and
the additional hydrogen (in the slurry water) promotes a
larger H2 fraction in the syngas compared to a dry-feed
gasifier design.
Following gasification, the raw syngas is cooled and
cleaned of contaminants. Two approaches for the initial
cooling step are the use of a direct water quench or abonds, and NOx emissions are lower than when using conventional
diesel fuel [Fleisch et al., 1997; Zhou et al.,
2000; Fleisch et al., 1995; Sorenson and Mikkelsen,
1995]. DME can be reformed into hydrogen at least as
easily as methanol, and thus is potentially suitable for future
use as a hydrogen source for stationary or vehicle
fuel cells. One drawback of DME as a vehicle fuel is the
need for modest pressurization to store it as a liquid (Table
1). DME can also be used as an LPG substitute in domestic
applications, e.g., cooking, where it burns with a
clean blue flame over a wide range of air/fuel ratios
[Fleisch et al., 1995; ICC, 2003]. DME is relatively inert,
non-corrosive, non-carcinogenic, almost non-toxic, and
does not form peroxides by prolonged exposure to air
[Hansen et al., 1995].
DME is produced globally today at a rate of about
150,000 tonnes (t) per year in small-scale facilities by dehydration
of MeOH [Naqvi, 2002]. Technologies are
available for converting syngas from natural gas or coal
directly into DME (rather than with intermediate methanol
production), but the small size of today’s DME markets
has not justified building direct conversion facilities,
which require relatively large scale to achieve attractive
economics. The Chinese Ningxia coal-to-DME project has
a planned output capacity of 830,000 t/yr DME using a
direct conversion process, and the principal intendedhigh-temperature syngas cooler. Either of these would be
followed by a wet scrubbing step to remove fine particles.
A water-gas shift (WGS) reactor is incorporated after the
initial cooling to adjust the ratio of H2 to CO in the syngas
to give an optimal ratio for subsequent downstream
chemical processing. Sulfur-tolerant water-gas shift catalysts
are available (e.g., a CoMo catalyst made by Haldor
Topsoe [2002]), so that sulfur removal (which is necessary
to protect further-downstream catalysts) can be done after
the shift. Additional steam may be added to the shift reactor
to ensure a sufficient steam-carbon ratio to avoid
coke formation [Katofsky, 1993]. Before the sulfur removal
step, an inexpensive activated carbon filter would
be used to capture trace contaminants such as mercury
and other heavy metals [Rutkowski et al., 2002].
The sulfur removal step is critical, both to limit SO2
emissions from the conversion facility (e.g., in the case
where some of the syngas is burned in a gas turbine) and
to protect the catalysts used in the downstream synthesis
step. The latter requirement places a stricter constraint on
sulfur removal than the former [Turk et al., 2001]. Sulfur
levels below 1 ppmv in the synthesis feed gas are required
to guarantee adequate catalyst life [Moore, 2003]. Several
technologies are commercially available that can achieve
such levels, including those that operate using physical
absorption into organic fluids (e.g., Selexol®
or Rectisol®
)
and others that operate by chemical reaction of amines
with the sulfur compounds in the gas.
Unlike chemical absorption processes, the effectiveness
of physical absorption processes is proportional to the partial
pressure of the gases to be removed (e.g., H2S). Since
the syngas is available at elevated pressure (> 60 bar) in
the systems considered here, physical absorption is the
preferred sulfur removal technology. The characteristics
and costs of Selexol®
technology, which in typical applications
(e.g., sulfur removal from syngas for gas turbine
combustion) achieves H2S concentrations down to 20
ppmv, but which can also achieve H2S removal to the 1
ppm level [Sharp et al., 2002], are the basis for the H2S
removal designs here. The captured H2S is typically converted
to elemental sulfur using the Claus process, with
tail gas clean-up in a SCOT plant. Following the Selexol
unit, a final sulfur guard bed (e.g, using zinc-oxide bed
material) is used to remove residual H2S to ppb levels.
Selexol solvent absorbs CO2 in addition to H2S. (The
solubility of CO2 in Selexol is about one-ninth that of
H2S [Breckenridge et al., 2000].) In theory, the removal
of all CO2 (along with the H2S) is desirable to maximize
downstream synthesis to methanol or DME (as discussed
in Section 3.1 below), but in practice some CO2 is required
in the gas to provide oxygen needed to maintain
the activity of the synthesis catalyst[3]. The CO2 may be
vented, captured for sale as a by-product, or captured for
below-ground storage. The idea of co-capture and co-storage
of H2S and CO2 has also been proposed [Chiesa et
al., 2003]. This would have significant cost advantages
for coping with sulfur, since no Claus/SCOT plant would
be needed to convert the H2S into elemental sulfur, and
separate systems for desorbing H2S and CO2 from theSelexol solvent would not be needed.
The clean syngas leaving the sulfur removal area is sent
to the synthesis area of the plant. The gas is preheated to
the operating temperature of the synthesis reactor
(~260ºC) before being fed into it. In a single pass of gas
through the synthesis reactor, only a portion of the CO
and H2 will be converted to the desired liquid fuel. After
synthesis, purification of the raw synthesis product by a
series of flash tanks and/or distillation steps produces the
final liquid fuel of interest.
In one of the basic plant configurations considered here
(Figure 1, upper) the syngas is passed only once through
the synthesis reactor (‘‘once-through’’ configuration). The
unconverted gas is used as fuel for a gas turbine. The hot
exhaust of the turbine is used, together with waste heat
recovered from various places in the process, to raise
steam to drive a steam turbine. The power generated by
the gas turbine/steam turbine combined cycle is sufficient
to provide the power needed to operate the plant, plus a
significant amount of power for export to the grid.
In the other basic plant configuration (Figure 1, lower),
most of the unconverted gas from the product recovery
area is returned to the synthesis reactor to generate additional
liquid fuel (‘‘recycle’’ configuration). The remainder
of the unconverted gas fuels a power cycle making only
enough power to meet the process needs, with no additional
electricity for export.

ผลลัพธ์ (ไทย) 1:

application is as a household cooking fuel [Lucas, 2002].In this paper, we present detailed process designs andperformance estimates for production of DME from coal,together with cost analysis. Since there are many similaritiesto methanol production, which is more widely understood,we include self-consistent analyses of methanolfrom coal for reference.2. Basic process configurations for indirect coalliquefactionFigure 1 illustrates two basic process configurations formaking MeOH, DME, or Fischer-Tropsch fuels by indirectcoal liquefaction. The difference between the two isthat in one case the only output from the facility is aliquid fuel. In the other case, electricity is a major coproduct.The two configurations are essentially identicalthrough the first few process steps.The first process step is gasification, which convertsthe coal into a ‘‘synthesis gas’’ (or syngas) containing primarilyhydrogen (H2) and carbon monoxide (CO). A varietyof gasifier designs are in commercial operationworldwide using coal or other dirty, low-value feedstocks(e.g., petroleum coke generated at refineries) [Simbeckand Johnson, 2001]. Here we have chosen to consider adesign based on the technology of Chevron/Texaco. Thisdesign uses partial oxidation of the coal in oxygen (generatedin a dedicated air separation unit) to provide therequisite heat to drive the gasification reactions. The coalis fed into the reactor in a water slurry, which has twoนัยสำคัญ สามารถทำอาหารในเรือการทำงานที่ความดันค่อนข้างสูง (75 แถบโรงงานต่างหากพิจารณาในเอกสารนี้), ให้ทางอุณหพลศาสตร์และต้นทุนผลประโยชน์กระบวนการโดยรวม และไฮโดรเจนเพิ่มเติม (ในสารละลายน้ำส่งเสริมการเศษส่วน H2 ใหญ่ใน syngas เมื่อเทียบกับอาหารแห้งการออกแบบของ gasifierต่อการแปรสภาพเป็นแก๊ส syngas ดิบคือระบายความร้อนด้วย และความสะอาดของสารปนเปื้อน วิธีที่สองสำหรับการเริ่มต้นขั้นตอนการทำความเย็นใช้ระงับน้ำโดยตรงหรือ abonds และโรงแรมน็อกซ์ปล่อยต่ำกว่าเมื่อใช้ทั่วไปน้ำมันดีเซล [Fleisch et al., 1997 โจว et al.,2000 Fleisch et al., 1995 Sorenson และ Mikkelsen1995] ได้ DME สามารถจะกลับเนื้อกลับตัวเป็นไฮโดรเจนน้อยเป็นได้เป็นเมทานอล และจึงอาจเหมาะสมสำหรับอนาคตใช้เป็นแหล่งไฮโดรเจนสำหรับเขียนหรือยานพาหนะเซลล์เชื้อเพลิง คืนหนึ่งของ DME เป็นเชื้อเพลิงยานพาหนะมีการต้องการ pressurization เจียมเนื้อเจียมตัวเพื่อเก็บไว้เป็นของเหลว (ตาราง1) ยังสามารถใช้ DME เป็นการทดแทนแก๊ส LPG ในประเทศโปรแกรมประยุกต์ เช่น ทำอาหาร ที่การเผาไหม้ด้วยการเปลวไฟสีฟ้าสะอาดมากกว่าความหลากหลายของอัตราส่วนอากาศ/เชื้อเพลิง[Fleisch et al., 1995 ICC, 2003] DME จะค่อนข้าง inertไม่กัดกร่อนไม่ใช่ carcinogenic เกือบจะไม่เป็น พิษ และแบบฟอร์ม peroxides นานตามอากาศ[แฮนเซ่น et al., 1995]DME ที่ผลิตทั่วโลกวันนี้ในอัตราเกี่ยวกับบริการ 150000 ตัน (t) ต่อปีในระบุโดยการคายน้ำof MeOH [Naqvi, 2002]. Technologies areavailable for converting syngas from natural gas or coaldirectly into DME (rather than with intermediate methanolproduction), but the small size of today’s DME marketshas not justified building direct conversion facilities,which require relatively large scale to achieve attractiveeconomics. The Chinese Ningxia coal-to-DME project hasa planned output capacity of 830,000 t/yr DME using adirect conversion process, and the principal intendedhigh-temperature syngas cooler. Either of these would befollowed by a wet scrubbing step to remove fine particles.A water-gas shift (WGS) reactor is incorporated after theinitial cooling to adjust the ratio of H2 to CO in the syngasto give an optimal ratio for subsequent downstreamchemical processing. Sulfur-tolerant water-gas shift catalystsare available (e.g., a CoMo catalyst made by HaldorTopsoe [2002]), so that sulfur removal (which is necessaryto protect further-downstream catalysts) can be done afterthe shift. Additional steam may be added to the shift reactorto ensure a sufficient steam-carbon ratio to avoidcoke formation [Katofsky, 1993]. Before the sulfur removalstep, an inexpensive activated carbon filter wouldbe used to capture trace contaminants such as mercuryand other heavy metals [Rutkowski et al., 2002].The sulfur removal step is critical, both to limit SO2emissions from the conversion facility (e.g., in the casewhere some of the syngas is burned in a gas turbine) andto protect the catalysts used in the downstream synthesisstep. The latter requirement places a stricter constraint onsulfur removal than the former [Turk et al., 2001]. Sulfurlevels below 1 ppmv in the synthesis feed gas are requiredto guarantee adequate catalyst life [Moore, 2003]. Severaltechnologies are commercially available that can achievesuch levels, including those that operate using physicalabsorption into organic fluids (e.g., Selexol® or Rectisol®)and others that operate by chemical reaction of amineswith the sulfur compounds in the gas.Unlike chemical absorption processes, the effectivenessof physical absorption processes is proportional to the partialpressure of the gases to be removed (e.g., H2S). Sincethe syngas is available at elevated pressure (> 60 bar) inthe systems considered here, physical absorption is thepreferred sulfur removal technology. The characteristicsand costs of Selexol® technology, which in typical applications(e.g., sulfur removal from syngas for gas turbinecombustion) achieves H2S concentrations down to 20ppmv, but which can also achieve H2S removal to the 1ppm level [Sharp et al., 2002], are the basis for the H2Sremoval designs here. The captured H2S is typically convertedto elemental sulfur using the Claus process, withtail gas clean-up in a SCOT plant. Following the Selexolunit, a final sulfur guard bed (e.g, using zinc-oxide bedmaterial) is used to remove residual H2S to ppb levels.Selexol solvent absorbs CO2 in addition to H2S. (Thesolubility of CO2 in Selexol is about one-ninth that ofH2S [Breckenridge et al., 2000].) In theory, the removalof all CO2 (along with the H2S) is desirable to maximizedownstream synthesis to methanol or DME (as discussedin Section 3.1 below), but in practice some CO2 is requiredin the gas to provide oxygen needed to maintainthe activity of the synthesis catalyst[3]. The CO2 may bevented, captured for sale as a by-product, or captured forbelow-ground storage. The idea of co-capture and co-storageof H2S and CO2 has also been proposed [Chiesa etal., 2003]. This would have significant cost advantagesfor coping with sulfur, since no Claus/SCOT plant wouldbe needed to convert the H2S into elemental sulfur, andseparate systems for desorbing H2S and CO2 from theSelexol solvent would not be needed.The clean syngas leaving the sulfur removal area is sentto the synthesis area of the plant. The gas is preheated tothe operating temperature of the synthesis reactor(~260ºC) before being fed into it. In a single pass of gasthrough the synthesis reactor, only a portion of the COand H2 will be converted to the desired liquid fuel. Aftersynthesis, purification of the raw synthesis product by aseries of flash tanks and/or distillation steps produces thefinal liquid fuel of interest.In one of the basic plant configurations considered here(Figure 1, upper) the syngas is passed only once through
the synthesis reactor (‘‘once-through’’ configuration). The
unconverted gas is used as fuel for a gas turbine. The hot
exhaust of the turbine is used, together with waste heat
recovered from various places in the process, to raise
steam to drive a steam turbine. The power generated by
the gas turbine/steam turbine combined cycle is sufficient
to provide the power needed to operate the plant, plus a
significant amount of power for export to the grid.
In the other basic plant configuration (Figure 1, lower),
most of the unconverted gas from the product recovery
area is returned to the synthesis reactor to generate additional
liquid fuel (‘‘recycle’’ configuration). The remainder
of the unconverted gas fuels a power cycle making only
enough power to meet the process needs, with no additional
electricity for export.

ผลลัพธ์ (ไทย) 3:

ใช้เป็นอาหารในครัวเรือน ลูคัสเชื้อเพลิง [ 2002 ] .
ในกระดาษนี้เรานำเสนอการออกแบบกระบวนการและการปฏิบัติของประมาณการสำหรับการผลิต DME

จากถ่านหิน ร่วมกับการวิเคราะห์ต้นทุน เนื่องจากมีความคล้ายคลึงกันมาก
การผลิตเมทานอลซึ่งเป็นอย่างกว้างขวางมากขึ้นเข้าใจ
เรารวมถึงตนเองสอดคล้องและเมทานอลจากถ่านหินอ้างอิง
.
2การกำหนดค่าพื้นฐานสำหรับทางอ้อม

รูปที่ 1 แสดงให้เห็นการแปรรูปถ่านหินสองกระบวนการพื้นฐานการกำหนดค่าสำหรับ
ทำให้ปริมาณเชื้อเพลิง DME หรือฟิชเชอร์ tropsch โดยการแปรรูปถ่านหินทางอ้อม

ความแตกต่างระหว่างสองคือ
ว่าในกรณีหนึ่ง ผลผลิตจากโรงงานเป็น
เชื้อเพลิงเหลว ในกรณีอื่น ๆ , ไฟฟ้าเป็นหลัก coproduct .
2
ตั้งค่าเป็นหลักเหมือนกันผ่านขั้นตอนกระบวนการสองสามครั้งแรก ขั้นตอนแรกคือ

จากที่แปลงถ่านหินเป็นก๊าซ ( หรือ ' ' ' 'synthesis แก๊สไฮโดรเจน ( H2 ) ที่ประกอบด้วยหลัก
) และคาร์บอนมอนอกไซด์ ( CO ) ความหลากหลายของการออกแบบเตาผลิตก๊าซเชื้อเพลิงใน

ทั่วโลกในเชิงพาณิชย์การใช้ถ่านหินหรือสกปรกอื่น ๆวัตถุดิบมูลค่าต่ำ
( เช่นการสร้างโรงกลั่นปิโตรเลียมโค้ก ) [ simbeck
และจอห์นสัน , 2544 ] .ที่นี่ที่เราได้เลือกที่จะพิจารณา
การออกแบบที่ใช้เทคโนโลยีของ บริษัท เชฟรอนเท็กซาโก / . การออกแบบนี้
ใช้ปฏิกิริยาออกซิเดชันบางส่วนของถ่านหินในออกซิเจน ( ที่สร้างขึ้นในหน่วยแยกอากาศโดยเฉพาะ

) การให้ความร้อนที่จำเป็นเพื่อขับก๊าซปฏิกิริยา ถ่านหิน
ถูกป้อนเข้าไปในเครื่องปฏิกรณ์น้ำน้ำซึ่งมี 2
นัยยะสำคัญ อาหารสามารถทำในเรือ