TANK WATER.
SOIL FERTILITY -- ANIMAL FEEDING -- TANK WATER -- SEPARATION OF
SOLIDS -- COLLECTING GREASE -- TESTING TANK WATER -- EVAPORATING TANK
WATER -- DESCRIPTION OF APPARATUS -- CLEANING EVAPORATORS -- TABLE OF
BOILING POINTS -- TESTING STICK -- COPPERAS IN WATER TO EVAPORATE --
SOLIDS IN WATER -- DRYING STICK -- VALUE OF TANKAGE -- QUANTITY OF
TANK WATER -- COST OF EVAPORATING.
=Soil Fertility.=--The constant drain on the soil by raising of grain;
feeding animals and sending them away for slaughter, and the non-return
of the nitrogen element has made great inroads on the productivity
of soil. Through volume after volume and in every manner possible,
economic writers are impressing this upon the agricultural interests
and advocating the making up of such deficit by rotating crops, turning
under legume and plants that might extract nitrogen from the air by the
processes of nature which daily are becoming more familiar to every
one. Value and demand for the nitrogenous elements for this purpose has
caused the packer to exercise all possible care to produce and conserve
for sale any and all nitrogenous products.
=Animal Feeding.=--Experiment has also shown that nitrogenous products
have a very high value as a nutritive food for growing and fattening
animals, so much so in fact, that in many agricultural districts the
entire output of tankage from local packing houses is now sold in the
immediate neighborhood for stock foods. Under various names evaporated
tank water is an ingredient of these.
=Tank Water.=--Invisible but in considerable quantity, nitrogenous
solids were formerly lost in the various waters from cooking, but
they are now collected and reduced to a semi-solid, or solid form.
These are classified under the one broad name of tank water, but they
include almost any water in which animal matter is cooked unless the
water be of such character that it can be used for edible purposes. The
chief sources of supply are rendering tank water, blood water, bone
house cooking water, ham and tripe boiling water, etc. It is estimated
that any water showing density of ¹⁄₂° Beaume scale is worthy of
concentration.
_Keeping Water Concentrated._--Evidently the more dilute the water,
the more water it is necessary to evaporate, and hence more costly to
concentrate. In raising the tanks so as to flow the oil from the tank
cocks, it is necessary at times to admit fresh water. To avoid this
the water from one tank is usually transferred to another of the same
character by use of a pump.
_Collection of Waters._--After the tankage has been dumped into the
skimming box and all grease skimmed off, the tank water should be drawn
into a separate vat. The “press water,” which is the water from the
pressing of the tankage, should also be collected. The floor drainage
except from the tank filling floor, and practically all water produced
in the tank house, should be collected; in fact, some operators go to
the extreme of not connecting the tank house sewer system to the city
sewer so as to intentionally preclude the wasting of water.
=Preparation of Solids.=--The tank water is collected in large vats for
processing. The solids or sludge is undesirable to handle, consequently
in draining the tank water from the surface vats into the storage,
it is necessary to have the holes of the screens in the surface vats
reduced to about one-quarter of an inch in size in order that all of
the solids will be retained in the surface vats and not be permitted to
go into the tank water catch basins.
The tank water storage vats should be equal to a day’s capacity and
should be filled in rotation in order that agitation will be going on
only in the vat being filled or the vat being emptied, and that the
water in the balance of the storage vats will be permitted to be held
under a settling process in the meantime, which is as follows: Heat
the water to a temperature of 180° to 185° F., and then allow it to
drop down to 170° F., carrying it at this temperature from eight to
twenty-four hours, according to the length of time it is possible to
carry the water for settling purposes, up to 36 hours is an advantage.
=Collecting Grease.=--In the surface boxes spoken of in preceding
chapter, it is very essential to agitate the tankage in the surface
vats and keep it under steam long enough for some of the grease to rise
to the top of the surface boxes and be skimmed off before the tank
water is run into the storage vats. Skim the grease very carefully from
the top of the water in any vat that is to be used for evaporation;
then pump the water to the evaporator supply tank. After the water is
pumped out of the basin, it will be necessary to remove the bottom of
settlings each time after the tank is emptied.
=Settlings in Bottom of Vat.=--Pump the bottoms from the holding tanks
into a surface box from which these settings are passed on to the press
cheeses with pressed tankage, so that the fibrous material will collect
the sludge. It is absolutely necessary that these settlings be taken
out of the storage vats each time the vats are emptied in order to keep
them sweet and to prevent the tank water from souring as it certainly
will, unless cleaned at least twice a week. It is much better to clean
them every time.
=Testing Tank Water.=--Tank water is tested with a standard hydrometer
for liquids heavier than water, and as stated previously, any water
indicating ¹⁄₂° on the Beaume scale, is collected.
A sample of the tank water is cooled to 150° F. Drop a hydrometer
into the water and take reading at a point on a level with the
water; a hydrometer reading from 1 to 20, is used for this purpose.
If hydrometer reads 2.00, the amount of the solids in the water is
estimated at 3.83 per cent as shown on the table for figuring tank
water. If the hydrometer should read 2.50, the estimated solids is
one-half of the difference between solids shown on table at 2° Beaume
and 3° Beaume added to solids at 2° Beaume which is 4.80 per cent.
=Evaporating Tank Water.=--The evaporating of tank water, it is
proposed to do in the most economical manner possible, and advantage
is taken of the fact that as the pressure is lowered the boiling point
is reduced. For example, water at atmospheric pressure and sea level
boils at 212° F., and water under a twenty-eight inch vacuum boils at
100° F. Advantage is taken of these physical facts in the evaporating
of tank water.
There are a number of types of evaporators using the same principle,
although we show one only, that which is most extensively used, the
well-known Swenson machine. This apparatus consists of one, two or
three cells, dependent upon the economy it is wanted to attain.
[Illustration: FIG. 73.--SWENSON EVAPORATOR.]
=Descriptive of the Apparatus.=--The cells are numbered _1_, _2_ and
_3_, beginning at the left. The rectangular box at the bottom of each
cell consists of a cast iron false head or chamber at either end, in
which copper flues are expanded. Steam is introduced into the chamber
of _No. 1_, and the tubes surrounded with tank water. The steam in the
coils causes the water to boil and the steam boiled off is passed to
the steam chamber of the second cell. The tank water in cell _No. 1_
by this boiling is condensed and is passed to cell _No. 2_, where a
further boiling takes place, and the concentrated liquid is passed to
cell _No. 3_ for its last boiling.
The auxiliary pumps shown are for transfer purposes from cell to cell,
and for pumping the condensate from the steam chambers.
_Vacuum._--The large pump at the right hand is the vacuum pump. The
vapor withdrawn from cell _No. 3_ by the withdrawal action of the
pump is condensed by the introduction of cold water in the conical
enlargement shown. This condensation produces a partial vacuum, the
customary gauge measurement showing 23 to 27 inches, dependent upon
the quantity and temperature of the water. This vacuum continues in
a lesser degree to the second cell, thence to the first and where
the vacuum usually maintained is six inches. By reference to the
table of boiling points the comparative temperature in each cell is
ascertainable.
=Cleaning the Evaporators.=--Evaporators to be effective must be clean,
on the same principle as cleaning boilers produce best results. At
regular intervals, say, fortnightly, they should be boiled out with a
solution of 75 lbs. caustic soda in 1500 gallons of water. This will
clean the flues and maintain the machine output.
TABLE OF BOILING POINTS.
29 inch vacuum 79.07° Fahr.
28 inch vacuum 101.15 Fahr.
27 inch vacuum 115.06 Fahr.
26 inch vacuum 125.38 Fahr.
25 inch vacuum 133.77 Fahr.
24 inch vacuum 140.64 Fahr.
23 inch vacuum 146.78 Fahr.
22 inch vacuum 152.16 Fahr.
21 inch vacuum 157.00 Fahr.
20 inch vacuum 161.42 Fahr.
19 inch vacuum 165.42 Fahr.
18 inch vacuum 169.14 Fahr.
17 inch vacuum 172.63 Fahr.
16 inch vacuum 175.93 Fahr.
15 inch vacuum 179.03 Fahr.
14 inch vacuum 181.92 Fahr.
13 inch vacuum 184.68 Fahr.
12 inch vacuum 187.31 Fahr.
11 inch vacuum 189.83 Fahr.
10 inch vacuum 192.43 Fahr.
5 inch vacuum 202.92 Fahr.
1 inch vacuum 212 Fahr.
=Storing Stick.=--The residue from the evaporators or the “Stick” as it
is now called, should be pumped into a receptacle fitted with closed
steam coils. The tank water vats are similarly fitted.
=Testing Stick.=--Stick is tested the same as tank water, excepting a
hydrometer graduated from 20° to 40° is used. It is usual to evaporate
to a density of 29° Beaume, which is 64.61 per cent dry solid. To
calculate the quantity of concentrated or dry stick containing 4 per
cent moisture produced from 29° Beaume stick, multiply the number of
gallons of stick by 10.27 lbs. to get weight of 29° Beaume stick; then
take 64.61 per cent of this weight, which is weight of dry solids, then
add 4 per cent moisture to this amount by dividing the weight of dry
solids by .96; the result is weight of concentrated tankage containing
4 per cent moisture.
=Copperas.=--This is usually “sulphate of iron” of commerce, although
some institutions make their supply thus: Using a lead-lined vat
holding about 200 gallons; into this put about 160 gallons of 60-degree
sulphuric acid, adding water enough to make the solution about 12°
Beaume. Into this solution place scrap iron of any description and
allow it to stand until the solution will dissolve no more iron.
Pump the solution into a shallow lead-lined vat with lead coils, and
evaporate to about 40° degrees Beaume. It is next drawn off into
barrels of fifty gallons each and to each barrel add forty pounds of
black oxide of manganese and thoroughly mix.
=Copperas in Water to Evaporate.=--An early practice and one which had
the merit of fixing free ammonia before it passes off in a gaseous form
was the introduction of copperas in tank water, while settling, and
before evaporation. The vats of tank water are tested with a Beaume
hydrometer and for every 2,000 gallons of tank water at indicated
degree, Beaume, ordinary commercial copperas should be added as follows:
Water testing 5° Baume 166 lbs. dry copperas
Water testing 4¹⁄₂° Baume 150 lbs. dry copperas
Water testing 4° Baume 133 lbs. dry copperas
Water testing 3¹⁄₂° Baume 117 lbs. dry copperas
Water testing 3° Baume 100 lbs. dry copperas
These varying amounts of copperas are put into a barrel of hot water
and thoroughly stirred until dissolved. The solution is then poured
into a vat of tank water, the mass allowed to stand six or eight
hours, and then skimmed off before being pumped to the evaporating
machine.
=Solids in Water.=--The percentage of solids and liquids, as well as
the respective weights in tank water at different degrees Beaume, are
shown in the following table:
TABLE FOR TANK WATER.
=======+======+=====+======+======
| | |Weight|
| Per | Per | of |Weight
Degrees| cent | cent| cubic| of
Baume |solids|water| foot |gallon
-------+------+-----+------+------
1 | 1.90|98.10| 62.14| 8.30
2 | 3.83|96.17| 62.46| 8.34
3 | 5.77|94.23| 62.79| 8.39
4 | 7.77|92.23| 63.11| 8.43
5 | 9.85|90.15| 63.43| 8.47
6 | 11.93|88.07| 63.91| 8.54
7 | 14.04|85.96| 64.41| 8.60
8 | 16.19|83.81| 64.89| 8.67
9 | 18.38|81.62| 65.38| 8.73
10 | 20.60|79.40| 65.81| 8.80
11 | 22.71|77.29| 66.39| 8.87
12 | 24.84|75.16| 66.92| 8.94
13 | 26.97|73.03| 67.44| 9.01
14 | 29.11|70.89| 67.97| 9.08
15 | 31.27|68.73| 68.49| 9.15
16 | 33.55|66.45| 69.05| 9.23
17 | 35.88|64.12| 69.61| 9.30
18 | 38.22|61.78| 70.17| 9.37
19 | 40.59|59.41| 70.72| 9.45
20 | 42.98|57.02| 71.28| 9.52
21 | 45.11|54.89| 71.89| 9.60
22 | 47.24|52.76| 72.79| 9.68
23 | 49.37|50.63| 73.09| 9.77
24 | 51.50|48.50| 73.70| 9.85
25 | 53.63|46.37| 74.30| 9.93
26 | 56.31|43.69| 74.95| 10.01
27 | 59.04|40.96| 75.60| 10.10
28 | 61.80|38.20| 76.25| 10.19
29 | 64.61|35.39| 76.90| 10.27
30 | 67.54|32.46| 77.55| 10.36
31 | 70.34|29.66| 78.35| 10.46
32 | 73.27|26.73| 78.94| 10.55
33 | 76.24|23.76| 79.64| 10.64
34 | 79.25|20.75| 80.33| 10.73
35 | 83.21|17.79| 81.00| 10.83
-------+------+-----+------+------
=Drying 29° Beaume Stick.=--This is done in two ways, by the use of
drying rolls and by mixing with drying tankage in a rotary dryer.
When drying stick over the rolls, evaporate it in the evaporators to
26° Beaume and mix with this 26° Beaume stick, about 17 per cent of
copperas before putting the mixture over the rolls. This has a tendency
to prevent the concentrated tankage from absorbing moisture when in
storage. Many operators dry stick without the use of copperas, but the
copperas prevents in a measure the stick absorbing moisture from the
air.
_Stick Rolls._--Fig. 74 shows a standard twin stick roll. This
equipment is made of two cast iron rolls built when new to sustain
50 lbs. pressure. The stick is deposited in a pan beneath and the
revolving roll collects a film of substance which is dried as the roll
revolves and is sliced from the surface of the roll by a close fitting
scraper, being removed in a powdered form.
[Illustration: FIG. 74.--STANDARD TWIN STICK ROLL.]
_Drying with Tankage._--The practice now generally adopted is the
mixing of the stick with tankage and drying in the standard fertilizer
dryer, using a fifteen foot dryer with stationary shell and revolving
shaft, with arms cylindrical type, usually known as the “Smith” dryer.
The usual charge is 4,000 lbs. pressed tankage and 1,200 lbs. stick,
agitating while the stick is being admitted so as to assist in equal
mixing. The stick should be at a temperature of 190° F., or near
thereto when used. The heated substance seems to produce less tailings,
or small balls requiring milling.
=Value of Tankage.=--To appreciate the value of the substances to be
collected in this manner, we refer to copy of test, made by an expert,
on a plant handling about 5,000 cattle and 5,000 hogs per week, as
follows:
ESTIMATE OF THE PRODUCTION AND VALUE OF TANKAGE MADE BY EVAPORATING
TANK WATER.
TEST FOR AMOUNT OF WATER DRAINED OFF VATS BEFORE PULLING TANKAGE.
=======+=======================================+=======+=======
| | | Av.
Tank | Product |Gallons|gallons
-------+---------------------------------------+-------+-------
No. 1 |Prime tallow (cutting room bones, etc.)| 1,445 |
No. 1 |Prime tallow (cutting room bones, etc.)| 1,734 | 1,589
| +-------+
No. 2 |Prime tallow (bed fat, etc.) | 1,645 |
No. 2 |Prime tallow (bed fat, etc.) | 1,365 |
No. 3 |Prime tallow (bed fat, etc.) | 1,426 |
No. 3 |Prime tallow (bed fat, etc.) | 1,827 | 1,566
| +-------+
No. 4 |No. 2 tallow (catch basin stuff) | 668 |
No. 6 |Pluck tank | 905 |
No. 9 |Pluck tank | 562 |
No. 10 |Pluck tank | 624 |
No. 10 |Pluck tank | 847 | 735
| +-------+
No. 11 |Prime steam lard | 1,382 |
No. 11 |Prime steam lard | 1,248 | 1,315
| +-------+
-------+---------------------------------------+-------+-------
TOTAL NUMBER OF TIMES TANKS FILLED AND COOKED.
No.
Product. Tanks
Prime tallow with cutting room bones 6
Prime tallow with bed fat, etc. 10
No. 2 tallow 6
Pluck tanks 13
Prime steam lard 6
--
Total 41
BASIS FOR ESTIMATE OF PRODUCTION.
======+========+========+========+======+========+=======
| Average| Total | Solids |Total | | Units
No. of|contents|contents|per gal.|solids|Per cent| of
Tanks| gals. | gals. | lbs. | lbs. |Ammonia |Ammonia
------+--------+--------+--------+------+--------+-------
6 | 1,589 | 9,534 | 0.88 | 8,390| 16.76 | 1,406
10 | 1,566 | 15,660 | 1.03 |16,130| 16.89 | 2,724
6 | 668 | 4,008 | .399 | 1,599| 14.59 | 233
13 | 735 | 9,555 | .763 | 7,290| 16.85 | 1,228
6 | 1,315 | 7,890 | .0481 | 380| 16.00 | 61
------+--------+--------+--------+------+--------+-------
| ... | 46,647 | ... |33,789| 16.73 | 5,652
------+--------+--------+--------+------+--------+-------
Total units of ammonia per tank, 5,652. Average units of ammonia per
tank, 16.73. 8 per cent of moisture, dry basis.
This production at $1.66 per unit would be worth $27.77 per ton, or the
yearly production would bring $24,396.32.
Figuring the production of tankage to be 66,000 pounds per week and
that with this could be mixed through the dryer 600 pounds or 107.3
gallons of stick, 25° Beaume with each ton of dry tankage--then 33 ×
600 pounds, or 19,800 pounds, would be the limit of production from the
tank water.
The regular tankage runs on an average of 10 per cent ammonia and 16.4
bone phosphate, and as shown above the production from the tank water
with 8 per cent moisture would run 16.73 per cent ammonia. The product
would therefore consist of the following:
=====================+======+========+=======+=========+=========
|Weight|Per cent| Units |Per cent | Units
Materials |pounds|Ammonia |Ammonia|Phosphate|Phosphate
---------------------+------+--------+-------+---------+---------
Regular tankage |66,000| 10.00 | 6,600 | 16.4 | 10,824
Evaporated tank water|19,800| 16.73 | 3,312 | ... | ...
---------------------+------+--------+-------+---------+---------
Total production |85,800| ... | 9,912 | ... | 10,824
---------------------+------+--------+-------+---------+---------
Analysis, ammonia 11.55%, bone phosphate 12.62%
Value per ton $19.93, or for the yearly production, $44,459.84.
Should there be added worthless material sufficient to reduce the
percentage of ammonia to 10, the following formula would apply:
=====================+======+========+=======+=========+=========
|Weight|Per cent| Units |Per cent | Units
Materials |pounds|Ammonia |Ammonia|Phosphate|Phosphate
---------------------+------+--------+-------+---------+---------
Regular tankage |66,000| 10.00 | 6,600 | 16.4 | 10,824
Evaporated tank water|19,800| 16.73 | 3,312 | ... | ...
Worthless material |13,320| ... | ... | ... | ...
---------------------+------+--------+-------+---------+---------
Total production |99,120| ... | 9,912 | ... | 10,824
---------------------+------+--------+-------+---------+---------
Analysis, ammonia 10%; bone phosphate 10.92%.
Value per ton $17.25¹⁄₂, or for yearly production $44,468.32
RECAPITULATION.
Value of total production for one year $44,468.32
Value of tankage for one year $30,030.00
6 per cent interest on $10,000 investment 600.00
15 per cent depreciation on $10,000 investment 1,500.00
Additional labor, five men, “full time” 2,340.00 34,470.00
----------------------
Net profit on investment $ 9,998.32
=Quantity of Tank Water Produced.=--This is variable, depending upon
closeness of saving and density; also quantity of solid substance
measured, and other items, but generally speaking from cattle
slaughtered--ten gallons per head, and from pigs two and one-half
gallons per head are collected.
=Expense of Evaporating Stick.=--The following test shows the cost of
producing stick through evaporators. The cost at the present time would
be 100% higher owing to coal costs:
COST OF EVAPORATING TANK WATER.
Duration of Test 9 hours 8¹⁄₂ hours
Average Steam Pressure--_1st effect_ 5.1 lbs. 5.1 lbs.
Average Vacuum--_1st effect_ 11.4 lbs. 11.9 lbs.
Average Vacuum--_2nd effect_ 19.0 lbs. 18.6 lbs.
Average Vacuum--_3rd effect_ 27.7 lbs. 27.4 lbs.
Density of Tank Water at 150° 3¹⁄₂° B. 2¹⁄₂° B.
Average Temperature of Tank Water 203° 199°
Gallons Tank Water Fed 11,476 9,625
Gallons Tank Water Fed Per Hour 1,275 1,132
Gallons Tank Water Fed Per Hour 1,338 1,220
Gallons Stick Produced 1,092.75 907
Density Stick at 150° 30° B. 28¹⁄₂° B.
Pounds Stick Produced (10.205 lbs. and
10.08 lbs. per gal.) 11,151 9,142
Pounds Water Evaporated 83,066 69,748
Pounds Steam Used--_1st effect_ 17,712 18,509
Pounds Steam Used--Pumps 11,210 10,972
------ ------
Pounds Steam Used--Total 28,922 29,481
Pounds Steam Used per 100 lbs. Stick--_1st
effect_ 159 202
Pounds Steam Used per 100 lbs. Stick--Pumps 100 120
--- ---
Pounds Steam Used per 100 lbs. Stick--Total 259 322
Cost Steam Used per 100 lbs. Stick--_1st
effect_ at $.132 per 1,000 lbs. $.021 $.027
Cost Steam Used per 100 lbs. Stick--Pumps .013 .016
---- -----
Cost Steam Used per 100 lbs. Stick--Total .034 .043
Pounds Steam Used per 100 lbs. Stick--Water
evaporated--_1st effect_ 21.3 26.6
Pounds Steam Used per 100 lbs. Stick--Pumps 13.5 42.3
---- ----
Pounds Steam Used per 100 lbs. Stick--Total 34.8 42.3
Cost Steam Used per 100 lbs. Stick, Water
evaporated--_1st effect_ .0028 .0035
Cost Steam Used per 100 lbs. Stick, Water
evaporated--Pumps .0018 .0021
----- -----
Cost Steam Used per 100 lbs. Stick, Water
evaporated--Total .0046 .0056
NOTE: The equivalent gallons concentrated from 10% to 70% solids are
calculated from a table and not from analysis of the tank water and
stick; therefore, are only approximately correct.
The steam cost at $0.132 per 1,000 pounds is far below present
average conditions.
=Quantity Stick Produced.=--The quantity of stick it is possible to
produce is indicated in the following table:
ANNUAL PRODUCTION TANK WATER AND STICK.
======================================================
Basis for Approximate
Killing Approximation Head
------------------------------------------------------
Cattle 208,304 1 to 1 208,304
Calves 36,474 7¹⁄₂ to 1 4,863
Sheep 416,325 7¹⁄₂ to 1 55,510
Packer Hogs 496,219 2¹⁄₂ to 1 231,569
Shipper Hogs 45,094 5 to 1 9,019
-------
Total approximate killing 509,265
Gallons tank water saved 4,912,484
Gallons tank water per approximate head 9.64
Pounds of Stick made 2,766,648
Pounds of Stick made per approximate head 5.43
The relative quantity of Stick to dried fertilizer produced is about
40%, but the stick is more valuable due to its higher ammonia content
and the mixture of the stick with the standard fertilizer increases the
value per ton of the fertilizer.