boiler deposits by keeping in suspension more of the
harmful foulants that can accumulate in boiler tubes. This highly effective proprietary terpolymer controls
both dried iron oxide and the more prevalent and difficult to control hydrated iron oxide in condensate
return and well water. The unique features of ACUMER 3100 terpolymer and the corresponding
benefits they provide in boiler service are presented below.
Feature
Your Benefit
Your Customer's Benefit
Superior inorganic
Helps keep surfaces clean for
Reduced downtime, lower fuel
particulate dispersant,
maximum heat transfer and
and maintenance costs.
especially for iron
corrosion resistance through
oxide and hydroxy-
effective boiler sludge control.
apatite.
Thermally and
Can be used over a broad
Single program for all
chemically stable.
range of temperature,
pressure range boilers.
pressure and pH.
Readily analyzed
Easily monitored.
Optimal economic dosage
at use concentrations.
Allows close dosage
readily maintained.
control.
©Rohm and Haas Company , 1999 PHYSICAL PROPERTIES
The typical physical properties of ACUMER 3100 terpolymer are listed in Table 1.
TABLE 1
TYPICAL PHYSICAL PROPERTIES
(These do not constitute specifications)
Total Solids, percent
43.3
Active Solids, percent
39.5
Molecular Weight
4500
Brookfield Viscosity, cps.
200
Specific Gravity
1.2
Bulk Density, lbs./gal. (g/cc)
10 (1.2)
pH
2.5
Lbs (Kg) of NaOH (100%) to neutralize
0.13
1 lb (kg) of ACUMER 3100
CHEMISTRY AND MECHANISM OF ACTION
ACUMER 3100 terpolymer contains three functional groups: strong acid (sulfonate), weak acid (carbox-
ylate), and a nonionic that provide optimal dispersancy for most particulates under a broad range of operat-
ing conditions.
Among the three functionalities, ACUMER 3100 carboxylate groups are most strongly attracted to particle
surfaces, allowing strong dispersant adsorption to boiler sludge. ACUMER 3100 sulfonate groups are only
weakly attracted to the particle surface and retain some residual negative charge to provide repulsion of similar-
ly charged particles in the boiler circuit. This repulsion prevents sludge particles from aggregating into larger
particles which can settle and deposit on tube surfaces. ACUMER 3100 nonionic groups provide both stronger
adsorption and steric repulsion to other particles, depending on the exact boiler conditions encountered.
This multi-functional action contrasts sharply to other dispersants, such as polyacrylic acid (PAA) or
poymethacrylic acid (PMAA), having only carboxylate functionality which can become strongly attached to
certain sludge particles, leaving little residual negative charge available to provide dispersancy. Other poly-
mers, such as those containing both sulfonated styrene and maleic acid (SSMA), can provide better disper-
sancy than PAA or PMA on some particle substrates, but do not have the nonionic group which allows
ACUMER 3100 terpolymer to function on a broader range of particles.
PERFORMANCE RESULTS
Bench-Top Dispersancy Studies
Extensive testing of ACUMER 3100 terpolymer has shown that it provides unsurpassed control of boiler
sludge. The polymer makes it possible to easily transport iron with calcium- and phosphate-containing
sludges for removal during blowdown. The excellent performance of ACUMER 3100 terpolymer for dis-
persing iron oxide is shown in Figure 1. Acumer 3100 terpolymer outperforms SSMA, phosphinocarboxylic
acid, acrylic acid/acrylamide and methacrylic acid polymers. Table 2 contains additional data on the superi-
or performance of ACUMER 3100 for dispersing hydroxyapatite, calcium carbonate and iron hydroxide
(hydrated iron oxide).
2 3
FIGURE 1. IRON OXIDE DISPERSANCY
BOILER WATER CONDITIONS, pH - 10.6
Test Conditions:
Polymer (active) = 3 ppm
Fe
2
O
3
- 700 ppm
Settling Time = 4 hours
Ca
+2
as CaCO
3
= 200 ppm
TABLE 2.
POLYMER PERFORMANCE FOR DISPERSING BOILER SLUDGE*
Dispersancy, NTU
Hydroxy-
Calcium
Hydrated
Polymer
apatite
Carbonate
Iron Oxide
Acumer 3100
65
104
20
Polyacrylic Acid
40
25
10
Polymethacrylic Acid
25
13
6
Phosphinocarboxylic Acid
27
18
6
Acrylic Acid/Acrylamide Copolymer
22
18
13
* These tests compared to 10-15 ppm active polymer at pH11 in 200 ppm Ca
+2
as CaCO
3
and used 700 ppm
hydroxyapatite, 700 ppm calcium carbonate or 10 ppm Fe(OH)
3
as Fe
+3
. Settling time is 1 hour.
Thermal And Hydrolytic Stability
ACUMER 3100 terpolymer is highly resistant to breakdown in aqueous solution under conditions of high
temperature, pressure, and pH. Hydrothermal stability studies of ACUMER 3100 terpolymer in synthetic
boiler water show no significant breakdown at 250°C/490°F (600 psig or 42 kg/cm
2
). However, consider-
able breakdown of the polymer does occur at 300°C/570°F (1200 psig or 84 kg/cm
2
) and, thus, is not recom-
mended for boiler pressure above 900 psig or 63 kg/cm
2
(280°C/530°F).
In contrast, thermogravimetric analysis of ACUMER 3100 terpolymer, as the sodium salt, shows that the onset of
degradation does not occur until about 370°C (698°F). Please note that thermogravimetric analysis (TGA) may not
simulate boiler conditions and this result is only provided for comparison to other boiler chemicals evaluated by TGA.
Samples of ACUMER 3100 terpolymer stored at pH 13.5 show no loss in performance even after storage for
six months at ambient temperature. 4
FORMULATING PHOSPHATE-BASED PROGRAMS
Calcium phosphate's extremely low solubility product enables phosphate added to boiler water to efficiently
precipitate calcium as calcium phosphate while preventing problem precipitates (calcium silicate, calcium
carbonate, and calcium sulfate). With proper boiler water alkalinity and phosphate concentration, the pre-
ferred hydroxyapatite precipitate can be formed and subsequently dispersed by ACUMER 3100 terpolymer
and removed during blowdown. Since phosphate can also precipitate magnesium (an adherent sludge),
control of the boiler water chemistry ensures that it precipitates as the more easily conditioned magnesium
silicate or magnesium hydroxide.
The type of phosphate used generally depends on the feed point within the boiler system and the alkalinity
of the boiler water. If the product is fed directly to the steam drum, orthophosphate is preferred. If the phos-
phate is added to the feedwater, a polyphosphate is preferred to avoid precipitation reactions from occurring
in the feedwater line.
The formulations listed in Table 3 are for phosphate-based boiler water treatment programs based on SHMP
(sodium hexametphosphate); as indicated in the foregoing discussion, they should be added to the feed-
water line. These formulations are not intended for commercial use as is but rather should be considered
starting-point formulations, requiring additional development, modification, and adaptation to specific
operating conditions.
TABLE 3
STARTING-POINT FORMULATIONS FOR THE CONTROL OF
BOILER SLUDGE DEPOSITS BASED ON
ACUMER 3100 TERPOLYMER
BW-87-1
BW-87-2
BW-87-3
Weight
Percent
Weight
Percent
Weight
Percent
Ingredients
Percent
Active
Percent
Active
Percent
Active
Deionized Water
82.49 77.29 72.69 Ucon 50 HB 5100
1
0.01 0.01 0.01 ACUMER 3100
2
7.50
3.0
7.50
3.0
7.50
3.0
Sodium hexameta-
10.00
10.0
15.00
15.0
20.00
20.0
phosphate
3
(food grade)
Totals
100.00
13.0
100.00
18.0
100.00
23.0
Ratio of SHMP/
ACUMER 3100
4
3.3/1
5.0/1
6.7/1
Dose formulation at 15 to 50 ppm into feedwater to maintain 30 to 60 ppm residual PO
4
in the boiler
circuit. pH of boiler water should be above pH10.
1
Union Carbide Company
2
Rohm and Haas Company
3
FMC Corporation
4
SHMP/ACUMER 3100 is the ratio of sodium hexametaphosphate to active ACUMER 3100
(expressed in acid form). The following graphs are designed to help determine the formulation and feed rate that will give 30-60 ppm
residual PO
4
and about 12-18 ppm active ACUMER 3100 terpolymer in the boiler circuit under a variety of
feedwater contaminant loadings and cycles of concentration.
Selecting The Appropriate Formulation
For a low-medium pressure boiler and assuming that feedwater iron contamination is less than 0.1 ppm, the
best formulation can be determined from Figure 2 based on feedwater calcium concentration and anticipated
number of cycles of concentration.
FIGURE 2. FORMULATION SELECTION AS A FUNCTION OF FEEDWATER
HARDNESS AND CYCLES OF CONCENTRATION
5
Graph assumes <0.1 ppm Fe in feedwater, and boiler pressure of 200-400 psig (14-28 Kg/cm
2
). If feedwater 0.2 ppm Fe, use next lower SHMP/ACUMER 3100 ratio. For higher boiler pressure, use next lower
SHMP/ACUMER 3100 ratio. Example 1:
A 300 psig (21 Kg/cm
2
) boiler operating at ten cycles of concentration and having 0.05 ppm iron in the feed-
water has a normal feedwater calcium concentration of about 2 ppm (as CaCO
3
). What is the appropriate
phosphate program formulation to use?
From Figure 2 based on 2 ppm Ca
+2
in the feedwater and ten cycles of concentration, Formulation BW-87-2
should be selected.
Determining Feed Rate
Figure 3 can be used to determine formulation feed rate based on the cycles of concentration of the boiler.
FIGURE 3. BOILER FORMULATION FEED RATE AS A FUNCTION OF
CYCLES OF CONCENTRATION
Example 2:
Formulation BW-87-2 has been selected for the boiler operation given in Example 1. What is the correct
feed rate needed to maintain about 12-18 ppm ACUMER 3100 terpolymer and 30-60 ppm residual phos-
phate in the boiler circuit?
From Figure 3, at ten cycles of concentration, about 50 ppm of Formulation BW-87-2 should be added to the
feedwater line.
6 7
Determining ACUMER 3100 And Residual Phosphate In Boiler Circuit
The