DESTRUCTOR (_continued from volume 8, slice 2, page 0108._)
... in main flues, &c. (g) The chimney draught must be assisted with
forced draught from fans or steam jet to a pressure of 1½ in. to 2 in.
under grates by water-gauge. (h) Where a destructor is required to
work without risk of nuisance to the neighbouring inhabitants, its
efficiency as a refuse destructor plant must be primarily kept in view
in designing the works, steam-raising being regarded as a secondary
consideration. Boilers should not be placed immediately over a furnace
so as to present a large cooling surface, whereby the temperature of
the gases is reduced before the organic matter has been thoroughly
burned. (i) Where steam-power and a high fuel efficiency are desired a
large percentage of CO_{2} should be sought in the furnaces with as
little excess of air as possible, and the flue gases should be
utilized in heating the air-supply to the grates, and the feed-water
to the boilers. (j) Ample boiler capacity and hot-water storage
feed-tanks should be included in the design where steam-power is
required.
[Sidenote: Cost.]
As to the initial cost of the erection of refuse destructors, few
trustworthy data can be given. The outlay necessarily depends, amongst
other things, upon the difficulty of preparing the site, upon the
nature of the foundations required, the height of the chimney-shaft,
the length of the inclined or approach roadway, and the varying prices
of labour and materials in different localities. As an example may be
mentioned the case of Bristol, where, in 1892, the total cost of
constructing a 16-cell Fryer destructor was £11,418, of which £2909
was expended on foundations, and £1689 on the chimney-shaft; the cost
of the destructor proper, buildings and approach road was therefore
£6820, or about £426 per cell. The cost per ton of burning refuse in
destructors depends mainly upon--(a) The price of labour in the
locality, and the number of "shifts" or changes of workmen per day;
(b) the type of furnace adopted; (c) the nature of the material to be
consumed; (d) the interest on and repayment of capital outlay. The
cost of burning ton for ton consumed, in high-temperature furnaces,
including labour and repairs, is not greater than in slow-combustion
destructors. The average cost of burning refuse at twenty-four
different towns throughout England, exclusive of interest on the cost
of the works, is 1s. 1½d. per ton burned; the minimum cost is 6d. per
ton at Bradford, and the maximum cost 2s. 10d. per ton at Battersea.
At Shoreditch the cost per ton for the year ending on the 25th of
March 1899, including labour, supervision, stores, repairs, &c. (but
exclusive of interest on cost of works), was 2s. 6.9d. The quantity of
refuse burned per cell per day of 24 hours varies from about 4 tons up
to 20 tons. The ordinary low-temperature destructor, with 25 sq. ft.
grate area, burns about 20 lb. of refuse per square foot of grate
area per hour, or between 5 and 6 tons per cell per 24 hours. The
Meldrum destructor furnaces at Rochdale burn as much as 66 lb. per
square foot of grate area per hour, and the Beaman and Deas destructor
at Llandudno 71.7 lb. per square foot per hour. The amount, however,
always depends materially on the care observed in stoking, the nature
of the material, the frequency of removal of clinker, and on the
question whether the whole of the refuse passed into the furnace is
thoroughly cremated.
[Sidenote: Residues:]
The amount of residue in the shape of clinker and fine ash varies from
22 to 37% of the bulk dealt with. From 25 to 30% is a very usual
amount. At Shoreditch, where the refuse consists of about 8% of straw,
paper, shavings, &c., the residue contains about 29% clinker, 2.7%
fine ash, .5% flue dust, and .6% old tins, making a total residue of
32.8%. As the residuum amounts to from one-fourth to one-third of the
total bulk of the refuse dealt with, it is a question of the utmost
importance that some profitable, or at least inexpensive, means should
be devised for its regular disposal. Among other purposes, it has been
used for bottoming for macadamized roads, for the manufacture of
concrete, for making paving slabs, for forming suburban footpaths or
cinder footwalks, and for the manufacture of mortar. The last is a
very general, and in many places profitable, mode of disposal. An
entirely new outlet has also arisen for the disposal of good
well-vitrified destructor clinker in connexion with the construction
of bacteria beds for sewage disposal, and in many districts its value
has, by this means, become greatly enhanced.
[Sidenote: Forced draught.]
Through defects in the design and management of many of the early
destructors complaints of nuisance frequently arose, and these have,
to some extent, brought destructor installations into disrepute.
Although some of the older furnaces were decided offenders in this
respect, that is by no means the case with the modern improved type of
high-temperature furnace; and often, were it not for the great
prominence in the landscape of a tall chimney-shaft, the existence of
a refuse destructor in a neighbourhood would not be generally known to
the inhabitants. A modern furnace, properly designed and worked, will
give rise to no nuisance, and may be safely erected in the midst of a
populous neighbourhood. To ensure the perfect cremation of the refuse
and of the gases given off, forced draught is essential. This is
supplied either as air draught delivered from a rapidly revolving fan,
or as steam blast, as in the Horsfall steam jet or the Meldrum blower.
With a forced blast less air is required to obtain complete combustion
than by chimney draught. The forced draught grate requires little more
than the quantity theoretically necessary, while with chimney draught
more than double the theoretical amount of air must be supplied. With
forced draught, too, a much higher temperature is attained, and if it
is properly worked, little or no cold air will enter the furnaces
during stoking operations. As far as possible a balance of pressure in
the cells during clinkering should be maintained just sufficient to
prevent an inrush of cold air through the flues. The forced draught
pressure should not exceed 2 in. water-gauge. The efficiency of the
combustion in the furnace is conveniently measured by the
"Econometer," which registers continuously and automatically the
proportion of CO_{2} passing away in the waste gases; the higher the
percentage of CO_{2} the more efficient the furnace, provided there is
no formation of CO, the presence of which would indicate incomplete
combustion. The theoretical maximum of CO_{2} for refuse burning is
about 20%; and, by maintaining an even clean fire, by admitting
secondary air over the fire, and by regulating the dampers or the
air-pressure in the ash-pit, an amount approximating to this
percentage may be attained in a well-designed furnace if properly
worked. If the proportion of free oxygen (i.e. excess of air) is
large, more air is passed through the furnace than is required for
complete combustion, and the heating of this excess is clearly a waste
of heat. The position of the econometer in testing should be as near
the furnace as possible, as there may be considerable air leakage
through the brickwork of the flues.
The air supply to modern furnaces is usually delivered hot, the inlet
air being first passed through an air-heater the temperature of which
is maintained by the waste gases in the main flue.
[Sidenote: Calorific value.]
The modern high-temperature destructor, to render the refuse and gases
perfectly innocuous and harmless, is worked at a temperature varying
from 1250° to 2000° F., and the maintenance of such temperatures has
very naturally suggested the possibility of utilizing this heat-energy
for the production of steam-power. Experience shows that a
considerable amount of energy may be derived from steam-raising
destructor stations, amply justifying a reasonable increase of
expenditure on plant and labour. The actual calorific value of the
refuse material necessarily varies, but, as a general average, with
suitably designed and properly managed plant, an evaporation of 1 lb.
of water per pound of refuse burned is a result which may be readily
attained, and affords a basis of calculation which engineers may
safely adopt in practice. Many destructor steam-raising plants,
however, give considerably higher results, evaporations approaching 2
lb. of water per pound of refuse being often met with under
favourable conditions.
From actual experience it may be accepted, therefore, that the
calorific value of unscreened house refuse varies from 1 to 2 lb. of
water evaporated per pound of refuse burned, the exact proportion
depending upon the quality and condition of the material dealt with.
Taking the evaporative power of coal at 10 lb. of water per pound of
coal, this gives for domestic house refuse a value of from {1/10} to
{1/5} that of coal; or, with coal at 20s. per ton, refuse has a
commercial value of from 2s. to 4s. per ton. In London the quantity of
house refuse amounts to about 1¼ million tons per annum, which is
equivalent to from 4 cwt. to 5 cwt. per head per annum. If it be
burned in furnaces giving an evaporation of 1 lb. of water per pound
of refuse, it would yield a total power annually of about 138 million
brake horse-power hours, and equivalent cost of coal at 20s. per ton
for this amount of power even when calculated upon the very low
estimate of 2 lb.[1] of coal per brake horse-power hour, works out at
over £123,000. On the same basis, the refuse of a medium-sized town,
with, say, a population of 70,000 yielding refuse at the rate of 5
cwt. per head per annum, would afford 112 indicated horse-power per
ton burned, and the total indicated horse-power hours per annum would
be
70,000 × 5 cwt.
--------------- × 112 = 1,960,000 I.H.P. hours annually.
20
If this were applied to the production of electric energy, the
electrical horse-power hours would be (with a dynamo efficiency of
90%)
1,960,000 × 90
-------------- = 1,764,000 E.H.P. hours per annum;
100
and the watt-hours per annum at the central station would be
1,764,000 × 746 = 1,315,944,000.
Allowing for a loss of 10% in distribution, this would give
1,184,349,600 watt-hours available in lamps, or with 8-candle-power
lamps taking 30 watts of current per lamp, we should have
1,184,349,600 watt-hours
------------------------ = 39,478,320 8-c.p. lamp-hours per annum;
30 watts
39,478,320
that is, ----------------- = 563 8-c.p. lamp hours per annum per
70,000 population head of population.
Taking the loss due to the storage which would be necessary at 20% on
three-quarters of the total or 15% upon the whole, there would be 478
8-c.p. lamp-hours per annum per head of the population: i.e. if the
power developed from the refuse were fully utilized, it would supply
electric light at the rate of one 8-c.p. lamp per head of the
population for about 1{1/3} hours for every night of the year.
[Sidenote: Difficulties.]
In actual practice, when the electric energy is for the purposes of
lighting only, difficulty has been experienced in fully utilizing the
thermal energy from a destructor plant owing to the want of adequate
means of storage either of the thermal or of the electric energy. A
destructor station usually yields a fairly definite amount of thermal
energy uniformly throughout the 24 hours, while the consumption of
electric-lighting current is extremely irregular, the maximum demand
being about four times the mean demand. The period during which the
demand exceeds the mean is comparatively short, and does not exceed
about 6 hours out of the 24, while for a portion of the time the
demand may not exceed {1/20}th of the maximum. This difficulty, at
first regarded as somewhat grave, is substantially minimized by the
provision of ample boiler capacity, or by the introduction of feed
thermal storage vessels in which hot feed-water may be stored during
the hours of light load (say 18 out of the 24), so that at the time of
maximum load the boiler may be filled directly from these vessels,
which work at the same pressure and temperature as the boiler.
Further, the difficulty above mentioned will disappear entirely at
stations where there is a fair day load which practically ceases at
about the hour when the illuminating load comes on, thus equalizing
the demand upon both destructor and electric plant throughout the 24
hours. This arises in cases where current is consumed during the day
for motors, fans, lifts, electric tramways, and other like purposes,
and, as the employment of electric energy for these services is
rapidly becoming general, no difficulty need be anticipated in the
successful working of combined destructor and electric plants where
these conditions prevail. The more uniform the electrical demand
becomes, the more fully may the power from a destructor station be
utilized.
In addition to combination with electric-lighting works, refuse
destructors are now very commonly installed in conjunction with
various other classes of power-using undertakings, including tramways,
water-works, sewage-pumping, artificial slab-making and
clinker-crushing works and others; and the increasingly large sums
which are being yearly expended in combined undertakings of this
character is perhaps the strongest evidence of the practical value of
such combinations where these several classes of work must be carried
on.
For further information on the subject, reference should be made to
William H. Maxwell, _Removal and Disposal of Town Refuse, with an
exhaustive treatment of Refuse Destructor Plants_ (London, 1899), with
a special _Supplement_ embodying later results (London, 1905).
See also the _Proceedings of the Incorporated Association of Municipal
and County Engineers_, vols. xiii. p. 216, xxii. p. 211, xxiv. p. 214
and xxv. p. 138; also the _Proceedings of the Institution of Civil
Engineers_, vols. cxxii. p. 443, cxxiv. p. 469, cxxxi. p. 413,
cxxxviii. p. 508, cxxix. p. 434, cxxx. pp. 213 and 347, cxxiii. pp.
369 and 498, cxxviii. p. 293 and cxxxv. p. 300. (W. H. MA.)
[1] With medium-sized steam plants, a consumption of 4 lb. of coal per
brake horse-power per hour is a very usual performance.
DE TABLEY, JOHN BYRNE LEICESTER WARREN, 3rd BARON (1835-1895), English
poet, eldest son of George Fleming Leicester (afterwards Warren), 2nd
Baron De Tabley, was born on the 26th of April 1835. He was educated at
Eton and Christ Church, Oxford, where he took his degree in 1856 with
second classes in classics and in law and modern history. In the autumn
of 1858 he went to Turkey as unpaid attaché to Lord Stratford de
Redcliffe, and two years later was called to the bar. He became an
officer in the Cheshire Yeomanry, and unsuccessfully contested
Mid-Cheshire in 1868 as a Liberal. After his father's second marriage in
1871 he removed to London, where he became a close friend of Tennyson
for several years. From 1877 till his succession to the title in 1887 he
was lost to his friends, assuming the life of a recluse. It was not till
1892 that he returned to London life, and enjoyed a sort of renaissance
of reputation and friendship. During the later years of his life Lord De
Tabley made many new friends, besides reopening old associations, and he
almost seemed to be gathering around him a small literary company when
his health broke, and he died on the 22nd of November 1895 at Ryde, in
his sixty-first year. He was buried at Little Peover in Cheshire.
Although his reputation will live almost exclusively as that of a poet,
De Tabley was a man of many studious tastes. He was at one time an
authority on numismatics; he wrote two novels; published _A Guide to the
Study of Book Plates_ (1880); and the fruit of his careful researches in
botany was printed posthumously in his elaborate _Flora of Cheshire_
(1899). Poetry, however, was his first and last passion, and to that he
devoted the best energies of his life. De Tabley's first impulse towards
poetry came from his friend George Fortescue, with whom he shared a
close companionship during his Oxford days, and whom he lost, as
Tennyson lost Hallam, within a few years of their taking their degrees.
Fortescue was killed by falling from the mast of Lord Drogheda's yacht
in November 1859, and this gloomy event plunged De Tabley into deep
depression. Between 1859 and 1862 De Tabley issued four little volumes
of pseudonymous verse (by G. F. Preston), in the production of which he
had been greatly stimulated by the sympathy of Fortescue. Once more he
assumed a pseudonym--his _Praeterita_ (1863) bearing the name of William
Lancaster. In the next year he published _Eclogues and Monodramas_,
followed in 1865 by _Studies in Verse_. These volumes all displayed
technical grace and much natural beauty; but it was not till the
publication of _Philoctetes_ in 1866 that De Tabley met with any wide
recognition. _Philoctetes_ bore the initials "M.A.," which, to the
author's dismay, were interpreted as meaning Matthew Arnold. He at once
disclosed his identity, and received the congratulations of his friends,
among whom were Tennyson, Browning and Gladstone. In 1867 he published
_Orestes_, in 1870 _Rehearsals_ and in 1873 _Searching the Net_. These
last two bore his own name, John Leicester Warren. He was somewhat
disappointed by their lukewarm reception, and when in 1876 _The Soldier
of Fortune_, a drama on which he had bestowed much careful labour,
proved a complete failure, he retired altogether from the literary
arena. It was not until 1893 that he was persuaded to return, and the
immediate success in that year of his _Poems, Dramatic and Lyrical_,
encouraged him to publish a second series in 1895, the year of his
death. The genuine interest with which these volumes were welcomed did
much to lighten the last years of a somewhat sombre and solitary life.
His posthumous poems were collected in 1902. The characteristics of De
Tabley's poetry are pre-eminently magnificence of style, derived from
close study of Milton, sonority, dignity, weight and colour. His passion
for detail was both a strength and a weakness: it lent a loving fidelity
to his description of natural objects, but it sometimes involved him in
a loss of simple effect from over-elaboration of treatment. He was
always a student of the classic poets, and drew much of his inspiration
directly from them. He was a true and a whole-hearted artist, who, as a
brother poet well said, "still climbed the clear cold altitudes of
song." His ambition was always for the heights, a region naturally
ice-bound at periods, but always a country of clear atmosphere and
bright, vivid outlines.
See an excellent sketch by E. Gosse in his _Critical Kit-Kats_ (1896).
(A. WA.)
DETAILLE, JEAN BAPTISTE ÉDOUARD (1848- ), French painter, was born in
Paris on the 5th of October 1848. After working as a pupil of
Meissonier's, he first exhibited, in the Salon of 1867, a picture
representing "A Corner of Meissonier's Studio." Military life was from
the first a principal attraction to the young painter, and he gained his
reputation by depicting the scenes of a soldier's life with every detail
truthfully rendered. He exhibited "A Halt" (1868); "Soldiers at rest,
during the Manoeuvres at the Camp of Saint Maur" (1869); "Engagement
between Cossacks and the Imperial Guard, 1814" (1870). The war of
1870-71 furnished him with a series of subjects which gained him
repeated successes. Among his more important pictures may be named "The
Conquerors" (1872); "The Retreat" (1873); "The Charge of the 9th
Regiment of Cuirassiers in the Village of Morsbronn, 6th August 1870"
(1874); "The Marching Regiment, Paris, December 1874" (1875); "A
Reconnaissance" (1876); "Hail to the Wounded!" (1877); "Bonaparte in
Egypt" (1878); the "Inauguration of the New Opera House"--a
water-colour; the "Defence of Champigny by Faron's Division" (1879). He
also worked with Alphonse de Neuville on the panorama of Rezonville. In
1884 he exhibited at the Salon the "Evening at Rezonville," a panoramic
study, and "The Dream" (1888), now in the Luxemburg. Detaille recorded
other events in the military history of his country: the "Sortie of the
Garrison of Huningue" (now in the Luxemburg), the "Vincendon Brigade,"
and "Bizerte," reminiscences of the expedition to Tunis. After a visit
to Russia, Detaille exhibited "The Cossacks of the Ataman" and "The
Hereditary Grand Duke at the Head of the Hussars of the Guard." Other
important works are: "Victims to Duty," "The Prince of Wales and the
Duke of Connaught" and "Pasteur's Funeral." In his picture of "Châlons,
9th October 1896," exhibited in the Salon, 1898, Detaille painted the
emperor and empress of Russia at a review, with M. Félix Faure. Detaille
became a member of the French Institute in 1898.
See Marius Vachon, _Detaille_ (Paris, 1898); Frédéric Masson,
_Édouard Detaille and his work_ (Paris and London, 1891); J. Claretie,
_Peintres et sculpteurs contemporains_ (Paris, 1876); G. Goetschy,
_Les Jeunes peintres militaires_ (Paris, 1878).
DETAINER (from _detain_, Lat. _detinere_), in law, the act of keeping a
person against his will, or the wrongful keeping of a person's goods, or
other real or personal property. A writ of detainer was a form for the
beginning of a personal action against a person already lodged within
the walls of a prison; it was superseded by the Judgment Act 1838.
DETERMINANT, in mathematics, a function which presents itself in the
solution of a system of simple equations.