Performance and power costs of H2-O2 combustion powered steam-MHD central power systems are estimated. Hydrogen gas is assumed to be transmitted by pipe from a remote coal gasifier into the city and converted to electricity in a steam MHD plant having an integral gaseous oxygen plant. These steam MHD systems appear to offer an attractive alternative to both in-city clean fueled conventional steam power plants and to remote coal fired power plants with underground electric transmission into the city. Status and plans are outlined for an experimental evaluation of H2-O2 combustion-driven MHD power generators at NASA Lewis Research Center

Nichols, L. D.

Seikel, G. R.

Smith, M.

English

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NASA TECHNICAL NASA TM X- 71520
MEMORANDUM
CUI (NASA-TM-X-71520) NASA LEWIS H2-02 MHD N74-19697'
PROGRAM (NASA) 8 p HC $4.00 CSCL 10A
Unclas
G3/03 33460
NASA LEWIS H2 -0 2 MHD PROGRAM NS STIARILrTY
by Marlin Smith, L, D. Nichols, and G R. Seikel
Lewis Research Center
Cleveland, Ohio
TECHNICAL PAPER proposed for presentation at
Fourteenth Symposium on Engineering Aspects of
Magnetohydrodynamics
Tullahoma, Tennessee, April 8-10, 1974
https://ntrs.nasa.gov/search.jsp?R=19740011584 2020-03-23T11:46:32+00:00Z
NASA LEWIS H -02 MHD PROGRAM
J. Merlin Smith, L. D. NIhoIs, and G. R. Seikel
NASA Lewis Resesarch Center
Cleveland, Ohio 44135
Abstract will be orientated toward understanding electrode
and boundary layer voltage drops and the cause of
Performance and power costs of H2 -02 combustion and remedies for axial voltage breakdown in MHD
powered steam-MHD central power systems are esti- ducts.
meted. Hydrogen gas is assumed to be transmitted
by pipe from a remote coal gasifier into the city ,II Steam MHD System performance and Cost Study
and converted to electricity in a steam MHD plant
having an integral gaseous oxygen plant. These Steam MHD System Performance
steam MHD systems appear to offer an attractive
alternative to both in-city clean fueled conven- The H2-02 steam MHD generator can be easily
tional steam power plants and to remote coal fired integrated into cycles using steam turbines. Fig.
power plants with underground electric trans- 1 shows one such cycle. Four options for this
S amission into the city. Status and plans are out- power plant cycle were examined in reference 2. Ini
lined for an experimental evaluation of H2-02  option 1, the H2 , 02, and the steam diluent to the
-- tmbustion-driven MHD power generators at NASA combustor are preheated to the steam bottoming
Lewis Research Center. plant temperature (839 K), the flow is expanded to
a total pressure of I atm in the MHHD generator. In:
I. introduction options 2, 3, and 4, 1500 K preheat is assumed and
the expansion is to a total pressure of 1, 0.5, and
The NASA Lewis Research Center has undertaken a 0.1 atm respectively. All options except option 4
program to evaluate the potential performance of use a low pressure turbine to expand the flow to a
12-02 combustion-driven MHD power generators. pressure of 1/10 atm before the steam is condensed.
Hydrogen was chosen because it possesses the In all options the combustor is operated stoichio-
highest energy content per unit total mass (fuel metric at 30 atm and 3468 K. To maintain this
and oxidizer) of the hydrocarbon fuels. It is combustion temperature for the two different
therefore especially attractive for mobile appli- preheat temperatures the steam diluent flow is
cations where the operating time is sufficiently varied from 17 to 30 percent of the total MHD
long that the fuel weight is large compared to the hydrogen and oxygen mass flow.
dry weight of the system. Hydrogen is also
attractive for stationary power plants since it is If the hydrogen and oxygen are preheated, the
a relatively cheap coal derived clean fuel which is cycle efficiency is increased more by recycling
easily transported by gas pipe. It also possesses water through the high pressure recuperative-boiler.
adequate power density when burned with 02 and of and turbine than by increasing the combustion
the hydrocarbon fuels requires the least amount of temperature. The gross efficiency of the high MHD
02 per unit heat release. Another advantage is expansion ratio cycle is 70 percent (using the
that its combustion product, I.e., steam, is con- higher heating value) for a preheat temperature of
densible and easily mated with existing steam power 1500 K. Thus, this steam MHD cycle has the poten-
plants. A further feature of H2 -02 combustion is tial for obtaining a net efficiency of over 60
that it is pollution free. percent after subtraction of the power required for
oxygen production. Even without preheat the high
Although hydrogen is an attractive fuel from a expansion ratio steam MHHD topped ccles offer the
systems standpoint, it has some undesirable potential of over 50 percent efficiency.
features for an MHHD generator. The main undesir-
able feature is the lower electrical conductivity Comparison of Power Systems
of the combustion products as compared to that of
the higher C/H ratio hydrocarbon fuels. This is Table I shows representative average power cost
due to lower flame temperature, large electron for conventional steam plants using various fuels
collision cross section of water vapor, OH reaction land for both-coal-air MHD and steam MHD systems.
with alkali metal seed material, and the formation In this table, energy and/or power transportation
of (OH)" ions. However, these limitations are costs are neglected and only east/midwest surface
partially offset by the lower molecular weight of Imined coal is considered. Fuel costs are based on
the hydrogen combustion products which results in a 1985 projections given in reference 3.
higher flow velocity for a given Mach number. Thisl I
higher velocity generates a higher Faraday voltage I Tabfe I shows that the option 3of reference 2
for a given magnetic field strength. This higher lis the most attractive steam MHD system. This 55
voltage may be particularly important in small Ipercent efficient system is also more attractive
mobile power plants where the large electrode and ithan all alternative clean fuel conventional steam
boundary layer voltage drops, 100-400 volts (see 1power plants, particularly if they are fueled from
reference 1), are a significant fraction of the domestic shale, coal, or crude.
total voltage generated. Unless these drops can be
eliminated through more advanced MHD generator Table I also shows that the direct coal fired
designs, hydrogen-fueled generators may have a power plants can produce power at the lowest
significant advantage. average cost, the lowest cost system being a con-
ventional coal-fired steam plant.with no SO,
Our Initial experimental program is directed removal. It is 0.9 mills/kW-hre below the coal-air'
toward evaluating the performance of H2 -02  MHD topped steam plant which would remove SOx.
generators at high voltage, i.e., high Mach number This coal-air MHD topped steam plant was
(2) and high magnetic field (7 tesla). This study investigated in reference 4. The cost estimates
made in the present study were based on configuration, as shown in figure 4, eight coils
reference 4. will be used (4 on either side of the MHHD duct
bore). These coils will produce approximately 7
The power production cost is only one major fac- tesla across the 30 cm magnet bore diameter. With
tor in determining future power plant choices; add the use of the lower strength fringing field out-
tional aspects of the cost of power in a city as side the magnet bore a MHD duct length of about 45
Well as the environmental Impact of. the power plant cm can be obtained. Aspect ratio considerations
must be considered. In figure 2 the cost of power then lead to a mean MHD duct hydraulic diameter of
in a city is evaluated for various power plant approximately 5 cm.
concepts. The city is assumed to be either 100
miles from east or midwest surface coal mines Run times are dictated by the capacity of the
and/or 1500 miles from western surface coal, syn- neon refrigeration system which allows one period
gas, syncrude (shale or coal), and domestic crude, of operation per day. In the present magnet con-
figuration this period of operation is approxi-
The calculated power costs include energy/power mately I minute at the highest magnetic field
transportation costs. Investigated are in-city strength although several minutes of operation is
power plants using coal and clean fuels, coal fired possible at lower field strengths. Since only a
power plants 100 miles from the city with either small number of short duration MHHD tests(of the
overhead or underground electric transmission, and order of 10 seconds) can be run each day, a heat-
western minehead coal fired power plants with sink cooled MHD duct will be used.
overhead transmission. For the hydrogen fueled
power plants the hydrgen is assumed to be piped to In the rocket engine modified for this program,
the city from a gasifier located 100 miles outside the gaseous H2 is injected uniformally into the
the city. combustion chamber through a porous stainless steel
Injection plate at the rear of the chamber. The
Figure 2 again shows that a 55 percent efficient gaseous 02 is injected through 36 injection tubes
steam MHD power plant has an attractive potential uniformally inserted into the H2 injection plate.
compared to domestic clean-fuel conventional steam In this design cesium seed injected into the
power plants. This type plant is used in many oxygen supply line as a 75 percent solution of
cities in the United States. Oil and gas fired ICsOH dissolved in water. While initial tests
power plants account for approximately 25 percent Indicate this method of injection is satisfactory
of the U.S. electric power production. a second injection system consisting of 18
Injection tubes for oxygen and seed (each tube
Figure 2 also shows that the steam MHD power Is separately fed from 02 and CsOH solution
cost will be higher than the in-city coal fired manifolds) is being fabricated. The second
power cost but may have lower cost if the coal Injection system was designed to insure that the
fired plant is required to be located 100 miles CsOH solution is injected uniformally into the
outside the city (the assumed gasifier location) combustion chamber.
and if electric power transmission into the city is
required to be underground like the hydrogen The combustion chamber and nozzle are water
transmission. cooled electrodeposited copper. The length of the
chamber and nozzle is 22.86 cm and the i.d. of the
ill. NASA Lewis H?-0 Experimental Program chamber is 6.35 cm. The nozzle is designed for
Mach 2 at the 4.96 cm diameter exit. The chamber
Two facilities are being used in this program, and nozzle have been tested for H2-02 stoichio-
The first is a rocket test facility in which pro- metric combustion at chamber pressures up to
posed MHD channels will be tested for structural 20 atm.
Integrity and lifetime. Diagnostic measurements
will be made with applied electric fields. While IV, Concluding Remarks
this facility does not provide total MHD channel
simulation, it is very useful because of the test H2-02 combustion powered steam-MHD central power
time limits of the second facility as will be dis- systems offer the potential of producing power
cussed later. The rocket test facility may also be without air pollution (except for the emission of
used to test various MHD system components (e.g., CO2 at a remote gasifier). Low thermal pollution
seed recovery systems, fuel and oxygen preheaters) for in-city power plants lower the cost of power
associated with the power generation cycle proposed; from clean fuels and lower the economic penalties
in reference 2. This facility has been completed 'associated with possibly requiring coal consumption
and is presently being checked out. Initial MHHD to be remote from cities. Steam MHD systems
duct tests are scheduled for the first quarter of should, in addition, be the least difficult MHD 1
1974. technology to develop because of their clean fuel
and relatively simple chemistry.
The second facility is an MHD power generation
facility which is now in the final design stage and! The initial program of the NASA Lewis H2-02 MHD i
is projected to be completed by the fourth quarter generator program is to investigate the performance
of 1974. The physical size of the MHHD channel is of generators at high voltage, i.e., high Mach
determined by the use of an existing cryogenic number (2) and high magnetic field (7 tesla). This
magnet (ref. 5) which will be modified for use in has particular application to small mobile power
the experiment. As shown in figure 3 this magnet units where electrode and boundary layer voltage
presently consists of a stack of 12 aluminum . drops are of the order of the voltage that is
magnet coils which are cooled with liquid neon. generated. Future plans include the study of
The coil bore diameter is 30 cm. The magnet other fuels, primarily the products of coal gasi-
develops 15 tesla at the magnet center. For the fication, i.e., H2, CH4 , and CO, in varying
MHD experiment the magnet dewar will be modified to combinations.
provide a 23 cm bore transverse to the coil center
line for inserting the MHD duct. In this
2
References
1. Wu, Y. C. L.; et al.: Investigation of leag-
onel Conducting Wall Generators. 13th Sym-
gpslum on the Engineering Aspects of Magneto-
hydrodynamics, Stanford Univ., Stanford,
Calif., March 1973.
2. Saikel, G. R.; Smith, J. M.; Nichols, L. D.:
12 -02 Combustion Powered Steam-MHD Central
Power Systems. The Hydrogen Economy Miami
Energy Conference of 1974, Univ. of Miami,
Coral Gables, Florida, March 1974.
3. Anon.: U. S. Energy Outlook: Report of the
National Petroleum Council, Committee on U.S.
Energy Outlook, vol. I, Summary. National
Petroleum Council Committee on U.S. Energy
Outlook, Dec. 1972.
4. Bergman, P. 0.; Plants, K. D.; Demeter, J. J.;
and Bienstock, D.': An Economic Evaluation of
HD)-Steam Powerplants Employing Coal
Gasification. BM-RI-7796, Bureau of Mines,
U.S. Dept. of Interior, 1973.
5. Laurence, J. C.: High-Field Electromagnets at
NASA Lewis Research Center, NASA TN D-4910,
Nov. 1968.
TABLE I - REPRESENTAT VE POWER COST
ENERGY/POWER TIANSPORTATION NEGLECTED
TYPE PLANT EFFI IEICY AV. FUEL COST AV. POWER.COST
mills/KW-hre  mil ls/kW-hre
CONVENTIONAL STEAM
East/Midwest Coal
No SOx Removal to 2.2 8.9
With SO, Removal ) 2.2 10.9
Oil
Domestic Crude +0 8.9 15.5
Imported Crude 0 6.2. 12.8
Syncrude - Shale +0 8.1 14.7
Syncrude - Coal to 10.4 17.0
Gas
Syngas - West Coal to 8.7 15.4
Imported LNG ) 7.1 13.7
Hydrogen
East/Midwest Coal +0 8.8 15.5
COAL-AIR MHD TOPPED STEAM
East/Midwest Coal 50 1.8 9.8
H2-02 STEAM MHD
East/Midwest Coal.
Option 1 8 7.3 13.0
Option 2 1 6.9 12.2
Option 3 i5 6.4 11.9
Optibn 4 s0 5.9 16.9
3
E-7907'
HYDROGEN, [LOW TEMPERATURE AND PRESSURE
30 ATM STEAM TURBINE WITH REGENERATION
POWERAIR GASEOUS
AIR ETC OXYGEN
N2, ETC PLANT ""ll
HEAT-- 02,30 ATM F
It
02 i CONDENSER
H2 MHD GENERATOR i
I COMBUSTOR I
4-
PRE- BOILER-
HEATER SEED
STEAM DILUENT WITH PUMPS
SEED, 30 ATM
BOTTOMING
ELECTRIC HEAT
POWERSPOWER S-67192
Figure 1. - H2-02 Combustion steam MHD power plant.
ELECTRIC PLANT LOCATION AND TYPE PLANT ENERGY/PUWER TRANSPORTATION IN-CITY POWER COST, MIL/kW-HRe
EFFI-
CIENCY,
% 5 10 15 20
I. IN-CITY PLANTS EAST/MIDWEST COAL 100 MI BY RAIL.
A. COAL-AIR WEST COAL 1500 MI BY EITHER UNIT
1. CONVENTIONAL STEAM OR INTEGRAL TRAIN
A. NO SO REMOVAL 40
B. WITH SO, REMOVAL 40
2. MHD TOPPED STEAM 50 r IMPORTED CRUDE AT PORT
B. CONVENTIONAL PLANTS 1500 MI PIPE TRANSMISSION EXCEPT U.S. CRUDE
CLEAN FUEL-AIR IMPORTED AND H2  SYNCRUDE SHALE
1. OIL 40 H2 AS BELOW I / '-SYNCRUDE COAL
2. GAS (SYNGAS) 40
3. HYDROGEN 40 L IMPORTED LNG AT PORT
C. H2-O2 STEAM MHD EAST/MIDWEST GASSIFIER AT COAL MINE r AVG COAL
(INTEGRAL 02 PLANT 55 WEST COAL 1500 MI TO GASSIFIER rEEAST/MIDWEST SURFACE COAL
GASSIFIER 100 MI FROM CITY) 100 MI GH2 PIPE TRANSMISSION WEST SURFACE COAL
- CONVENTIONAL TRANSPORTATION
II. COAL PLANTS 100 MI FROM CITY EASTIMIDWEST PLANT AT COAL MINE (UNIT TRAIN, ETC)
A. OVERHEAD ELECTRIC TRANS WEST COAL 1500 MI BY RAIL :ADVANCED TECH INTEGRAL TRAIN
1. STEAM SOX REMOVAL 40 100 MI ELECTRIC TRANS
2. MHD TOPPED STEAM 50
B. UNDERGROUND ELECTRIC
TRANS
1. STEAM SOX REMOVAL 40
2. MHD TOPPED STEAM 50
III. WESTERN COAL MINE PLANTS 1500 MI OVERHEAD ELECTRIC TRANS
A. STEAM SOx REMOVAL 40
B. MHD TOPPED STEAM 50
Figure 2. - Comparison of city power costs for various powerplant concepts.
VACUUM
JACKET- -- RESEARCH DEWAR
I -- ;..TELEVISION AND
- - LIGHTING PORTS
CURRENT
OUT
LIQUID-NITROGEN-
INSULATING COOLED ELECTRICAL
SPACE BARS- BUS BARS
MAGNET
COILS - -- CURRENT IN
.LIQUID-NITROGEN
PRECOOL LINES
LIQUID-NITROGEN
VESSEL
ITO -LIQUID-NEON
VACUUM FILL LINE
PUMP
Figure 3. - Liquid-neon-cooled aluminum electromagnet.
STOICHIOMETRIC COMBUSTOR
Cs0H + H20
:-ALUMINUM
COILS
VACUUM
r LN2
Figure 4. - H2-02 MHD generator experiment.


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