[Gasification] back on-track [was] off topic discussion

[Peter Singfield]

Tom and Mike;

It would be really great if the Archives could be searched in a complete
and proper manner.

In this present example -- "grate" -- and allowing results in programmable
config -- such as by date -- or where another word needs by there
(refractory -- or stainless -- etc)

When I tried the Google search engine it did not point to the Gas list
archives -- but the entire I-net -- very confusing!!

I haver archived many of the past discussion -- if time today I will look
through those older ones and post some as examples.

I see a lot of questions repeated that were so completely well answered in
entire threads years gone by.

Such as producer gas production from oils --- blue gas -- water gas -- etc.

All with math models in place -- clear explanations -- and so9 many hard
references to other sources.

Maybe organizing the Arcs should be a top priority project??

As mentioned -- people could research first -- then ask questions later --
referring to specific past postings.

This would greatly advance gasification projects.

OK -- just went and picked one fast example -- from 2000 -- see appended

There is so much technical resources in those archives -- so very much --
if we have accomplished anything -- it is that.

Peter/Belize

At 08:56 PM 5/1/2007 -0700, Tom Miles wrote:
>We have seen the "August 2004" problem before. Sometimes we have had
>problems with the software rebuilding the archive when we've changed
>servers. If it's broken Mike will fix it for us.   
>
>The archives should go back to 1996 when we started the list. If the early
>ones don't show up on the Google search on the gasification site
>(http://gasifiers.bioenergylists.org/ ) they will show up on a Google web
>search. That's why we put them in the format we did when we created the
>list. 
>
>Tom
>

***************appended************

Date: Sun, 24 Sep 2000 07:59:54 -0500
To: gasification at crest.org
From: Peter Singfield <snkm at btl.net>
Subject: GAS-L: Power From Solar Heat (1913)


Folks -- the list has been kind of slow lately. I know the following is off
topic -- but just went through the chore of scanning this all in. figured
some of the old timers on this list will get a chuckle or two out of it.

So -- a blast from the past ---

Peter Singfield
Belize

****************************************

OK --- Scanned in from my:

"Marks Mechanical Engineers Handbook"

Published: 1924 (MacGraw-Hill Book Company)


POWER FROM SOLAR HEAT

The heat received per minute from the sun on 1 sq. ft. of surface normal to
the sun’s rays above the atmosphere of the earth amounts to 7.12 B.t.u.
(0.168 h.p. per sq. ft.), but, before reaching the earth where it can be
utilized, part of this heat is absorbed by water vapor and dust suspended
in the, atmosphere. In vast areas in the tropics and in certain
semi-tropical and arid sections (e.g., Arizona, Egypt), however, the air is
dry and clear, this loss is small, and sun power can be profitably produced
provided coal is very expensive and the cost of the considerable land area
required for a plant is low.

A. S. E. Ackermann (Jour. Roy. Soc. Arts, Apr. 30, 1915) states the
theoretical thermal efficiency of a solar heat absorber to be e = [Dsa — pk
* (T to the 4 rth — 2/3A to the 4 rth) — (1 — r)Dsa]/Dsa, where:

D = width of reflector, ft.; 

s = solar constant = 7.12 B.t.u. per sq. ft. per mm.; 

a = coefficient of atmospheric transmission = 0.7; 

p = perimeter of boiler, ft.; 

k = boiler radiation constant 10 to the minus 16 * 0.36 B.t.u. per sq. ft.
per mm.; 

T = boiler temperature, deg. fahr. abs.; 

A  = temperature of reflectors, deg. fahr. abs. (= atmos. temp. + 9 deg.); 

r = efficiency of silvered glass as a reflector of heat — taken as 0.6. 

Also, theoretical overall thermal efficiency of a sun-power plant = e1 = e
* (T — 568)/T, where 568 is the absolute temperature of the condenser, deg.
fahr. (assumed constant). 

In the Cairo plant, D = 12.67 ft. and p 2.92 ft. Assuming A 561 deg. and
solving equation for e1 for various values of T and plotting the results,
it is found that the maximum value for e, (5.9 per cent.) is obtained when
T = 231 deg. (= 692 deg. abs.) or the temperature for a steam pressure of
21 lb. abs. The actual maximum overall efficiency of the plant was found to
be 4.32 per cent., showing that about 75 per cent, of the boiler h.p.
theoretically possible was obtained.

In a 50-b.h.p. plant installed in 1913 at Cairo, Egypt, by Frank Shumann
(Manchester Assn. of Engrs., March 14, 1914), the sun’s rays are
concentrated on the flat bottom of a cast-iron boiler by silvered panes of
ordinary window glass arranged in frames so as to form approximate
parabolic reflectors, which frames are so geared that the engine (working
through a friction clutch governed by a thermostatic device) intermittently
turns them and keeps them facing the sun throughout its course during the
entire day. This boiler generates steam at atmospheric pressure (14.7 lb.
per sq. in.) which is utilized in a specially designed condensing engine
that yields 1 b.h.p. on a consump­tion of 22 lb. of steam. (For larger
plants the use of low-pressure turbines is proposed.) 

When the sun is obscured by clouds the engine will continue to generate
power economically until the pressure drops to about 4 lb. abs. To provide
power over rainy spells of 2 or 3 days, additional plant must be provided
to heat water to 212 deg. for storage in insulated tanks. The latitude of
Cairo is 30 deg. N.; at a location 1000 miles nearer the equator the Cairo
plant would yield 65 b.h.p.

The steam-producing part of the Cairo plant cost $7600. With interest and
depreciation at 10 per cent., the annual charge would be $760. An
equivalent coal-burning plant with stack, boiler and buildings would cost
$3750, and the annual charge at the same rate would be $375, or $385 less
than for the sun-power plant. Assuming a coal consumption of 2 lb. per
b.h.p. hour, the fuel annually required for 365 ten-hour days would amount
to 163 long tons. 

That is, the sun-power plant will compete on an even basis with a
coal-burning plant using coal costing but ($385/163 =) $2.36 per long ton.
For particulars regarding sun-power plants using less efficient heat
absorbers consisting of shallow, glass-covered, water-filled wooden basins
of large area, and also the use of ether or sulphur dioxide as the working
fluid instead of steam, see articles by Messrs. Shumann and H. E. Willsie,
Eng. News, May 13, 1909. A brief sketch of former efforts to utilize solar
energy, and a bibliography of the subject, are included in the paper by Mr.
Ackermann cited above.


*****************************************

HOT-AIR ENGINES

Hot-air engines are heat engines in which air is employed as the working
substance, operating in the Stirling or Ericsson cycles (see p. 327) or
modifications of them. Their bulk per h.p. of capacity is great as compared
to steam or gas engines and their efficiency low. They find use, however,
in small sizes for domestic pumping work. Bryan Donkin (“ Gas, Oil and Air
Engines”) gives the following data on such motors:

            Cyl.  Stroke
Engine    dia in.  in.  Rpm   Ihp    BHP 	Lb. fuel per hr. per
                                          Ihp	Bhp
Buckett	24.0	16.0	61	20.20	14.40	1.8	2.5
Beniér	13.4	13.8	117	5.80	4.00	8.1	8.6
Bailey	14.6	6.9	106	2.40	1.30	4.2	7.6
Rider	       6.7	9.5	138	0.81	0.23

The actual thermal efficiency of the Buckett engine, assuming the fuel
(coke) to have a calorific value of 12,000 B.t.u. per lb., is 2546/(2.5 X
12,000) = 8.48 per cent. Similarly, that of the Bailey engine is 2.8 per
cent. A steam engine of the size and speed of the Buckett engine, with a
mean effective pressure of but 30 lb. per sq. in., would develop over three
times the indicated horse power.


***********************

There -- that should keep you busy. If you could you get the refs referred
to here:

"For particulars regarding sun-power plants using less efficient heat
absorbers consisting of shallow, glass-covered, water-filled wooden basins
of large area, and also the use of ether or sulphur dioxide as the working
fluid instead of steam, see articles by Messrs. Shumann and H. E. Willsie,
Eng. News, May 13, 1909. A brief sketch of former efforts to utilize solar
energy, and a bibliography of the subject, are included in the paper by Mr.
Ackermann cited above."

Probably would answer a lot of questions regarding refrigeration working
fluid "boilers" and power plants.

Peter


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