For on-site, continuous, bulk water purification, a dual-monitored, two-pass system employs two successive banks of mixed-bed, strong-based resin cylinders. Raw water first flows down through a bank of primary cylinders in parallel. The outlets of the primary cylinders are connected in parallel via an overhead carry-over pipe to a smaller bank of polisher cylinders whose outlets are connected in parallel via a final filter to a discharge outlet. Probes monitoring the concentration of impurities are located in the carry-over pipe and following the final filter. The efficient arrangement of cylinders in a van allows easy replacement of exhausted cylinders without interrupting water treatment.

BACKGROUND OF THE INVENTION 
The invention relates generally to the field of water treatment, and more 
particularly to mobile water demineralization apparatus. 
Standard municipal water supplies typically contain various impurities in 
small concentrations, such as silica, chlorine, calcium and magnesium. 
However, many industries require large amounts of water of a higher degree 
of purity, for example, in boilers to prevent scale and corrosion and in 
chemical processes to insure process integrity. Often these industries 
have large onsite installations for water purification. A sampling of 
industries which regularly use high quality water in large quantities 
includes electric utilities, especially nuclear power plants, steamships, 
U.S. Navy, U.S. Air Force, U.S. Coastguard, Laboratories, electronics 
manufacturers, and breweries. 
Mobile demineralization units have the advantage that they can provide pure 
water at any location without requiring the user to make a permanent 
investment in this type of facility. In addition, the mobile demineralizer 
is available on an emergency basis when standard equipment fails or is 
unavailable or inadequate. For example, a particularly advantageous 
application of mobile demineralizers is providing pure water to steamships 
at the dock. One drawback of mobile demineralizing units, of course, is 
that they are limited in the quantity of demineralizing resin that can be 
carried. One such system previously used a one-pass system through 
demineralizers in a van but the quality of the water produced was 
inadequate for many applications. Another type of mobile system previously 
in use passed water through a large filtration tank. However, the 
purification operation had to be interrupted periodically to allow the van 
to return to its home base to replenish the exhausted demineralizing 
resin. 
SUMMARY OF THE INVENTION 
The general purpose of the invention is to provide a mobile water 
demineralization facility with the capability of continuously producing 
extremely high quality water for any nuclear grade requirement or high 
purity use with the capability of exchanging the demineralizing resin as 
it becomes exhausted, on an incremental basis without halting water 
production at any time. A corollary object of the invention is to provide 
a configuration for a mobile unit which provides maximum utilization of 
space in an otherwise standard van and allows easy replacement of 
demineralizing resin. 
These and other objects of the invention are accomplished in a mobile 
demineralizer for on-site, continuous, bulk water purification using a 
dual monitored two-pass system through two banks of strong-based, 
mixed-bed resin cylinders. Raw water is introduced in parallel to a bank 
of primary cylinders. The outlets of the primary cylinders are connected 
in parallel via an overhead carry-over pipe to a bank of polisher 
cylinders fewer in number than the primary cylinders, but filled with the 
same mixed-bed resin. The outlets of the polisher cylinders are connected 
in parallel via a final filter and water meter to a discharge outlet. 
Probes monitoring the concentration of impurities are located in the 
carry-over pipe between the primary and polisher cylinders and following 
the final filter. The cylinders are arranged in a special space saving 
configuration in a standard van with quick-disconnect valves permitting 
easy replacement of exhausted cylinders without interrupting water 
treatment.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The mobile demineralizer shown in FIGS. 1 and 2 is designed to provide an 
unlimited quantity of extremely high quality water on a continuous basis 
at any location. Normal procedure is to take municipal water from the 
nearest fire hydrant and pass it through the demineralizing van. Quality 
control is assured through the constant supervision of field operators who 
remain with the mobile unit whenever it is in service. 
FIG. 1 shows a standard step van 10. The rectangular storage area 12 in the 
back of the van 10 houses two banks of commercially available 
strong-based, mixed-bed demineralizer cylinders 14. Each cylinder is 
charged with anion and cation resins in a ratio of approximately two to 
one. The cylinders typically measure 8 inches in diameter and about 36 
inches in length and are vertically oriented. 
A bank 16 of 20 primary cylinders 14 is arranged in two rows along the left 
sidewall of the storage compartment of the van as viewed in FIG. 1. An 
optional test bench 18 with a sink can be inserted in the primary cylinder 
bank 16 against the sidewall of the van. A second bank 20 composed of 14 
cylinders 14 is arranged in two rows against the right sidewall of the 
storage compartment 12 as shown in FIG. 1. The cylinders in the second 
bank 20 are referred to as "polishers." 
Bulkheads and railings are used as necessary to retain the cylinders in the 
configuration as shown in FIG. 1 during travel. However, any appropriate 
system of tie-down straps or receptacles for restraining the cylinders can 
be used. The furthest aft portion of the storage area 12 along the right 
sidewall comprises a storage cabinet 22 housing spare parts, fittings, 
hoses, boots, etc. The interior volume of the storage area 12 between the 
primary and polisher banks 16 and 20 can be used for spare cylinders as 
well as a work area for service personnel. 
In FIG. 2 the water distribution lines of the system are illustrated. Raw 
water enters the mobile demineralizer van 10 via a standard 21/2 inch 
firehose fitting 24 on the left side of the van at the rear as shown in 
FIG. 1, and is passed to the bank 16 of primary cylinders via a three inch 
overhead input manifold pipe 26 (not shown in FIG. 1) which extends over 
the two rows of primary cylinders inside the van 10. The input manifold 
pipe 26 has 20 outlet fittings (not shown), one for each of the 20 primary 
cylinders. Each outlet fitting of the input manifold pipe 26 is connected 
via a short length of plastic tubing 28 to a respective one of the primary 
cylinders. The plastic tubing 28 extends to a 3/4 inch opening in the top 
of the cylinder 14 and terminates in a top distributor 30 comprising a 3/4 
inch six inch length of perforated (60 mesh) plastic tubing through which 
the raw water is introduced into the mixed-bed resin in the cylinder. The 
raw water flows down through the mixed-bed resin in each of the primary 
cylinders and is collected in a bottom distributor 32 which is a 
horizontal section of perforated plastic like the top distributor lying 
approximately on the bottom of the cylinder. The bottom distributor 32 is 
connected to a suitable fitting in the bottom of the cylinder 14 to a 
galvanized riser 34 which extends upwards along the outer circumference of 
each cylinder through a locating collar 36 to an overhead primary 
carry-over manifold pipe 38a. As in the case of the input manifold 26 the 
carry-over manifold 38a has 20 fittings receiving tubing 34 from each of 
the cylinders in the primary bank 16. Thus the raw water is introduced in 
parallel to all of the cylinders 14 in the primary cylinder bank 16, and 
water which has flowed down through the mixed-bed resin is taken out 
through the bottom distributor 32 and passed in parallel through the 
outlet tubing 34 to the carry-over manifold 38a. 
The primary carry-over manifold pipe 38a passes the output of the primary 
cylinder bank 16 through a transverse section of pipe 38b at the upper 
forward end of the storage compartment 12 in the van 10. A total dissolved 
solids probe 40 is located midway along the pipe section 38b to measure 
the conductivity of the water and thus to derive the extent of 
demineralization at this point in the process. The transverse segment 38b 
of carry-over pipe leads to a secondary carry-over manifold pipe segment 
38c which extends over the polisher cylinder bank 20 providing 14 outlet 
fittings for introducing semi-purified water into the polisher cylinders 
via tubing 28 as in the primary cylinders 16. Purified water collects at 
the bottom of the polisher cylinders and is passed by a bottom distributor 
32 and outlet riser tubing 34 to a discharge manifold pipe 42 which has 14 
fittings receiving the outlet ends of the tubing 34 from the polisher 
cylinders. The discharge manifold pipe 42 passes the finished water 
through a 25 to 30 micron final filter 44 of conventional construction and 
a three inch water meter 46 to a demineralized water discharge outlet 48 
in the form of a 21/2 inch firehose connection located on the right side 
of the van 10 (as viewed in FIG. 1). A conductivity probe 50 is located 
between the final filter 44 and the water meter 46. 
The purpose of the final filter is tp protect against introduction of resin 
into the water stream by a damged bottom distributor in any of the 
cylinders 14. If this happens, the final filter takes the resin out. 
The conductivity probe 40 on the carry-over pipe segment 38b is 
electrically connected to a meter 40a located on or near the dashboard of 
the van 10. The meter 40a reads total dissolved solids in parts per 
million (PPM) and allows the service personnel to perform intermediate 
process monitoring to guard against depletion or exhaustion of any of the 
cylinders in the primary cylinder bank 16. The second conductivity probe 
50 is connected to a meter 50a located on the left sidewall of the van 10 
directly above the test bench 18. The meter 50a reads directly in 
micromhos to indicate the concentration of ions in the finished water 
product. 
FIG. 3 shows in detail the fittings and valves associated with a 
representative cylinder 14, enabling removal and replacement of individual 
cylinders without interrupting water treatment. Each cylinder 14 as shown 
in FIG. 1 has the same equipment as shown in FIG. 3. Immediately above the 
collar 36 are detachable yokes 52 which are held in place with knurled 
bolts 54. The ends of the corresponding inlet and outlet tubing 28 and 34 
for the cylinder are received in the yoke 52. Unbolting yoke 52 
disconnects the tubing from the cylinder. Behind the yokes 52 are a pair 
of manual butterfly or gate-type valves 56 inserted respectively in the 
inlet and outlet tubing 28 and 34. In removing a cylinder, 14, the 
technician flips the valves 56 one turn to shut off the water flow to the 
cylinder, unbolts the yoke 52 by hand and removes the cylinder which 
weighs about 100 lbs. carrying approximately two gallons of water. A fresh 
cylinder 14 is placed in position, and after reconnecting the tubing 28 
and 34, the valves 56 are opened. This procedure is repeated until all of 
the exhausted cylinders have been replaced. 
In operation, a nuclear power plant, for example, which needs a large 
quantity of high grade water on an emergency basis, places a call to the 
nearest mobile demineralizer service center. One or more vans equipped as 
shown in FIGS. 1 and 2 are dispatched to the site. Before demineralization 
begins, the service technician performes a chemical analysis of the raw 
water at the test bench 18. The demineralized water outlet fitting 48 is 
connected directly to a supply pipe running to the nuclear power plant 
facility. The inlet fitting 24 is connected to a municipal water supply 
(fire hydrant) or any other suitable source of municipal grade water. The 
water supply should have a minimum pressure of 40 pounds per square inch. 
If adequate water pressure is not available at the site, a mobile power 
booster pump may be used between the source and the raw water inlet 24 of 
the mobile demineralizer. The raw water flows into the input manifold pipe 
26, down through the primary cylinder bank 16, from the primary cylinders 
around the overhead carry-over pipes 38a, 38b and 38c, into the polisher 
cylinder bank 20, from the polisher cylinders to the discharge manifold 
42, passing through the filter 44 and water meter 46 to the demineralized 
water outlet 48 at a nominal flow rate of 100 gallons per minute. At this 
rate, it takes water roughly 40 to 45 seconds to flow through the mobile 
demineralizer. The standard procedure calls for routine water analysis 
every hour along with water meter readings. The quality is also monitored 
constantly with the conductivity meters 40a and 50a. As the demineralizer 
cylinders 14 are exhausted, they are replaced individually one at a time 
without disrupting the water service. The exhausted demineralizer 
cylinders are returned to the nearest plant for regeneration; thus no 
regeneration waste disposal problem is created at the site. For relatively 
long term operation, the mobile demineralizer will require at least one 
additional support vehicle for transporting demineralizer cylinders to and 
from the on-site mobile demineralizer, which remains hooked up and in 
operation at all times. 
The quality of water in the above described system is available to less 
than one micromho with a silica concentration of one PPB and one PPB for 
chloride and sodium ions. 
The invention may be embodied in other specific forms without departing 
from its spirit or its central characteristics. The present embodiment as 
shown and described in connection with FIGS. 1, 2, and 3 is therefore to 
be considered in all respects as illustrative and not restrictive. The 
scope of the invention is indicated by the appended claims rather than by 
the foregoing description, and all changes which come within the meaning 
and range of equivalents of the claims are therefore inteded to be 
embraced therein.