DE2758540A1 - PROCESS FOR THE REMOVAL AND PREVENTION OF BIOLOGICAL SLUDGE AND SLUDGE FORMATION - Google Patents

Description

27585AQ - 3 -

NaIcο Chemical Company, Oak Brook, Illlnioe, V St A.

Process for the removal and prevention of biological Sludge and sludge formation

The invention relates to a method for removing and preventing the formation of silt and sludge on surfaces.

Industry cooling system such as cooling towers and heat exchange coolers with a one-time throughput often develop large volumes biological silt materials that adhere to the heat transfer surfaces. These silt materials reduce the flow of water in heat exchangers. The overall heat transfer efficiency of these units is also reduced

A classic method of preventing silt formation was hitherto the treatment of the water in these systems with industrial biocides. Although this method had some success, it did not solve the problem of removal

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existing deposits. In certain cases it is also impractical to treat these systems with large doses of biocides. »In some cases, biosides are not as extensive either effective in preventing the growth of silt-forming microorganisms! s4 prevent men

If it were possible to remove these silt masses quickly from cooling systems in industry using simple chemicals with low economic evils and to prevent their rebuilding quickly and easily, a valuable contribution to the enrichment of technology could be made, _etc.

The invention proposes a method for removing and preventing the build-up of biological silt on the surfaces technical and industrial cooling systems and the like, which is characterized in that it is used when operating diesel Cooling systems, e.g. cooling towers, used water with at least Oi5 ppm of a propylene oxide-ethylene oxide copolymer treated, this polymer consisting of a polyoxypropylene glycol polymer with a molecular weight of 1500-2000, with 5 up to 30% by weight of ethylene oxide has been converted, consists

According to a preferred embodiment of the invention, these Polymers in a dosage range of between 0.5 - 50 ppm and particularly preferably used from 0.5-30 ppm

According to a further preferred embodiment of the invention

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these copolymers are used in combination with biocides, in particular oxidizing biocides, to prevent this to support against recurring microbiological growth and to sterilize areas that have been made free of deposits by the action of the copolymers «In In certain cases, the copolymers presumably interact with the oxidizing biocides and not only provide improved dispersibility of existing biological deposits, but also make it possible for the biocide to develop its full effectiveness »

According to the invention it becomes possible to remove microbiological deposits to treat the heat exchange surfaces of both cooling tower f systems based on recirculation as well as cooling units single throughput occur · The latter units normally obtain their cooling water from a large supply4 those of water such as a lake, river or pond, lead the same into a heat exchange relationship with a liquid or a gas, after which it returns to its original form without being used again Source is traced back

Preferred representatives of the copolymers described above are commercially available from Wyandotte Chemical Company under the name "Üluronlos". Particularly useful Fluronics that can be used in the practice of the invention are Pluronice L61 and Pluronics L62 · both have Piu T "nnio" Materi alien This is a polyoxypropylene-Grundmole-

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kül, which has a molecular weight of about 1750 <> In the case of Pluronic L61, this polyoxypropylene glycol base is converted with 10 wt. % ethylene oxide and has an average molecular weight of about 2000. Pluronic L62 contains the polyoxypropylene glycol base converted with 20 wt .-% Ithylenoxid and has an average molecular weight of about 2500. a more detailed description of these materials and their preparation methods can be found in U.S. Patent No. 2,674 ₀ 619 ₀

example 1

To determine the effectiveness of various materials when dispersing existing organically produced silt material a single-cell, laboratory-scale cooling tower with compressed air ; electricity used. The basic data of this cooling tower and its

\

\ environment are:

I.

ι Cooling process: experimental heat exchange

pipes j

Total capacity: 20 liters!

Recirculation speed 7 * 57 liters per minute "i Blow-off speed: 70 cnr per minute " Leakage water: Ohicago -leitungawaseer

Δ Τ: 4 ⁰ C

Concentration: 3

pH tower water: 8.5

Hardness: 4} 5 ppm (as oaloium carbonate) Temperature: 38 ⁰ O

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Water loading: 4-5 »4- liters per 2M hour.

50 ppm of ethylene glycol were added to each of the tower's drinking water and a source of organic phosphorus in the form of a phosphate ester. The tower was operated for 4 days, which caused a substantial formation of silt masses on the metallic heat exchange surfaces.

10 ppm of the specific chemical to be tested was added to the tower water and allowed to circulate for 1 hour. At the end of this period, a biomass analysis of the basin water was performed using a biometer (from DuPont); the bio \ meter is described in the publication "DuPont 760 Luminescence Biometer ^'1 December 1970 and also in the U8-PSS 3 · 359 · 973rd

The results of this test are summarized in Tab. I. Table I.

10ppm with 1 hour contact (data determined with biometer)

Chemical ftBiomass-lndermm

1 · non-ionic (polyol) condensate d. Ethylene oxide with a hydrophobic basic structure (propyl oxide with propylene glycol), Pluronic L-61 66.4 %

2 · nonionic polyethoxylated

straight-chain alcohol 58.5 %

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Table I continued

3o Triscyanoäthylkokosdiamin 4-7.3 % 4 «, polyoxyethylene sorbitan ester of fatty and
Resin acids and alkylarylsulfonate, mixture

(non-ionic) 45.8 % 5o cationic ethylene oxide condensation products

of N-tallow propylenediamine 35 »8 %

6o nonionic N, N-dimethylstearamide 34.7 %

7o monoamine (cationic) (coconut mononitrile) 31.3 %

8e sodium polyacrylate 3Ί »Ί % j

9o nonionic aminopolyglycol condensate 30.0 %

1Oo cationic coconut diamine 25.6 %

11 ο non-ionic ethoxylated alcohol 21.2 %

12o lignosulfonate, anionic 10.3%

(30 ppm / 2 hours)

Ι3β sodium salt of an amphoteric surface-active agent 5.8 % 14. Polyacrylic acid (homopolymer) 4.7 % 15 «, non-ionic octylphenoxypolyethoxyethanol 4.1 %

example II

In addition, additional commercially available surfactants and dispersants were tested at a concentration of 10 ppm. Some of these materials are said to have bactericidal activity. This special group of materials, which In lab, It

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shows no evidence of biodispersibility.

Table II

Products showing no biodispersibility * at 10 ppm

1 «, Onamine RO * 1- (2-Hydroxyethyl) -2, n-heptadecenyl-2-

imidazoline, cationic

2 ο Ammonyx 27 * Alkyltrimethylemmonlumchlorid 3o cyanoethyllertes

Coconut diamine * (monodiamine) ^ ■ o BTC-2125 M * Onyx dual quat, cathioic 5 Surco 5025 non-ionic, mixed fatty acid diet-

nolaaid-Eondensat 6 Surfonic N-40 non-ionic alkyl aryl polyethylene glycol

ether

7. NaIcο 670 polymer

8. Hakon 10 non-ionic alkylphenoxy polyoxyethylene

ethanol

* biocidal effects can mask biodispersibility

Example III In another tower laboratory test, Pluronic L62

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using standard plate counting procedures in place of the Biometer monitor techniques tested and was approved for his Activity comparable to the Pluronic L61 »

Example IV

In addition to dispersing existing silt masses, the hats used according to the invention are able to prevent the build-up of silt. In another series of tests using the chemicals of the invention, the material was kept in the test cooling tower at a dose of 10 ppm; the tower was in a clean condition. The tower was operated for 11 days before the build-up of silt became visible _o As already stated, silt became visible towards the end of 4 days

As already indicated, the copolymers are particularly effective when they are used in combination with certain water-soluble oxidizing biocides. B ₀ sodium hypochlorite, is used as chlorine gas or as a water-dispersible organic compound that can release chlorine _o

It is also noteworthy that certain beneficial effects can be obtained by using the copolymer of the invention in combination with organic biocides such as Z ₀ B ₀ methylene bisthiocyanate "

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As stated, 1st chlorine or a chlorine-releasing compound the preferred biocide for use in combination with the copolymers of the invention for the purpose of dispersing Terhandener bio » logical separations and prevention of their subsequent build-up.

The chlorination practices involved in treating industrial Cooling waters applied vary considerably. Most often, the chlorine or chlorine-releasing compound is slowly added to the system and then added to those present in the system Allowed microorganisms to act. When the chlorine is allowed to act on the microorganisms. When the chlorine acts on the microorganisms and comes into contact with organic matter which is often present in such systems, it is absorbed or chemically converted to a degree where it is not longer than free chlorine can be determined. Thus, the system me is treated with the formation of so-called chlorine residues or residual chlorine content, which in most cases hardly exceeds 2 ppm and usually hardly go beyond 1 ppm. A typical residual chlorine produced by typical chlorination practices would be about 0.2 ppm.

In order to illustrate the advantages that are obtained by using the copolymers in combination with chlorine, the fol + - the additional examples are described below:

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- 12 example V

This test was conducted on a nuclear power plant in the Midwest of the United States conducted _β The specially used tower already pointed silt deposits on the wings and also a decreased cooling efficiency, capacitor-purity factors could determine how based _o

Three dosing parameters were assessed:

1o 15 ppm Pluronic L61 single charge (single slug) with 0.05 ppm GL ₂

2o 5 ppm Pluronic L61 single load with 12.12 ppm Cig 3o maximum 13.7 ppm Gl ₂ alone.

The addition of Pluronic L61 in conjunction with the chlorination resulted in a percentage improvement in the purity factor (CF) in both the high and low pressure capacitors. The results of this test are summarized in Fig. 1 and Table III "

Table III

% maximum CF treatment condenser improvement time

Pluronic L61 15 ppm] low pressure 7.24 6.5 hours _B.

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Port set zuiuc of Table III

0.05

Cl ₀ J

Fluronic L61 15 ppm 0.05 ppm Gl,

■]

Pluronic L61 5 PP *

12.12 ppm

σι,

Pluronic L61 5 ppm 12.12 ppm Cl ₉

High pressure

Low pressure

High pressure

6.09 2.61 3.80

9.5 hours 6 hours no 6 hours no

no biodisper Low pressure ". . ----- 0.55 2 Stdno lubricant Cl ₀
12.4 ppm i.d. no biodisper greed High pressure 1.06 2 Hours » 12.4 ppm Cl ₂

Another positive indication of biodispersion activity was the loss of titratable chlorine from recirculating water within 2 hours in the system treated with Pluronic L61, while 9 hours are required for an elimination ▼ on chlorine residues without reaching the biodispersant « Since Pluronic L61 shows no chlorine consumption at the application concentrations, it can be concluded that the biodispersant releases silt organisms from the cooling system, which quickly react with the available chlorine and reduce it to the zero level

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Example VI

The location for this test was a cooling tower at a power plant company of the American Midwest. This society has seen noticeable condenser growth over the past few years due to microbiological growth in the recirculating Water system compared to »The microbiological growth is due to the communal sewage flow, which is in the recirculating Water system is used »This sewer runoff contains a high content of microorganisms and organic Nutrients for the microorganisms, from which the enormous potential for microbiological growth in the recirculating water system explained. Chlorination before and after the slip softening, phosphate removal, chlorination on the cooling towers and intermittent ones Additions of commercially available biocides were found to be ineffective in controlling microbiological separation in the system

The analysis of the recirculating water and analyzes of the separation showed that the primary cause of separation is microbiological growth _o A complete system overview was created in order to obtain information on basic data »

The instrumentation of the unit No. ₀ 2 (d _o h. Enddifferenzthermometer, vacuum gauge, back pressure (turbine) manometer "™ * different investment instruments) has been calibrated.

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Based on the above table reveal that the unit in the appropriate time at 60 MW, a final difference from 5.5 to 6.7 ⁰ C (10-12 ° F) and a back pressure of 8.4- to 8.9 Torr was held.

Dosage; 30 ppm (best value in the tower) Initial dosage for cleaning the system The operating dosage after cleaning was 1-2 ppm. The chemicals should be added during the chlorination.

Results: It was found as a basic tendency that Pluronic L61 the final difference of 6.1 ° C (11 ° F) to 2.2 ° C (4 ⁰ F) and the back pressure of 8.4 Torr to 6.35 Torr down sat.

The addition of Pluronic L61 was simultaneous at 1200 hours started the chlorination. At 1600 hours the TDS reading in the tower rose to 8400 umho from 5000 umho. The water was cloudy and foamed, which is to be assessed as an indication of the rapid dispersing power of Pluronic L61.

On the first day the terminal differential and back pressure began to decrease.

2 and 3 · day final difference and back pressure (5 ° F) and corresponding to 6.35 to 6.9 Torr stabilized at 2.2 ° C (4 ° F) to 2.8 ⁰ O. This translates into a reduction of 3.9 ° C (7 ° F) for the final differential and 2.0 torr for the back pressure.

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Back pressure reduction; Figures 2 and 3 show the readings at

1400 hours and 1700 hours "The back pressure readings went from 8.4 Torr to 6.35 peat at full load." Apply counter pressure of 6.35 peat; therefore there is an increased power output of 0.8%. 2.54 Torr back pressure equivalent to 1% loss in the power output _o Figo 2 and 3 show readings in accordance with 1400 hrs. And 1700 hrs _o and let the relative effects of ambient temperature and relative ven moisture recognize "The reading at 1400 hrs. Was probably the hottest time of the day and the 1700 hour reading the average temperature of the day.

A comparison of the counter pressure manometer solutions with the vacuum Chart recorder and the barometric pressure meter in the system (barometric pressure minus vacuum equals counter pressure) which have a close relationship. Therefore the back pressure manometer reading is a reliable measure for the indication of condensate or lazy, substance formation.

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Endditference; FIG _o 2 and 3 show the corresponding readings at 1400 STDE and 17 hrs _o In this diagram, the final difference (Terminal difference) against the back pressure at 60 MW load is (full load) is applied. The final difference was lowered from 6.1 to 2.2 ⁰ C ⁰ O or an average of 3.9 ^0C. Despite the recalibrated thermometer, an error in reading the thermometer's close scale sequence will cause an error of +, 1.1 ⁰ O (2 ⁰ F). The most important of this reading is the fact that it serves as a good indicator of condenser digestion. The fact that the final difference is falling indicates that putrefaction has been removed. More accurate final difference data can be obtained by using a thermocouple temperature measuring device. The unit No. · 2 is provided for a final difference of 2.8 ° 0 (5 ° F) to 3.3 ⁰ O (6 ° F) on the basis that the absolute Druclf is konvertriert up to the temperature of the saturated Vasserdampfes. The fact that the final readings of the system falling to 2.2 ⁰ C (4 ⁰ F), wherein

ο an error of + 1.1 C, shows that the condensate

gate is clean and works almost as intended

Total count (Total Count): Sine the total count (colonies / ml)

was done on a limited basis. Fig. 4 shows the

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TC plotted against TDS ₀ The total count was carried out before the start of the previous treatment in order to confirm the presence of microbiological growth as the primary cause of the condenser putrefaction. At 0900 hours on the day before the chemical treatment, the TO was numerically too high for a count (-TNTC ) ₀ The TC was carried out using a portable Millipore Kulturausriistungo The sample was diluted 1: 1000 with sterilized water and a discarded Glaspakspitze. The sample was then incubated for 24 hours. The colonies that had grown after 24 hours were counted and compared with a comparison table. Due to the limited time and range of the comparison tables available, only six areas could be counted (10K, 30K, 50K , IOOK, 3OOK and TNTQ) ₀ However, this was sufficient to determine the trend of microbiological growth in the system. The TC was reduced to 3OOK on the first day and stood at 3 "day to 50K ₀ This indicates that the microbiological growth had been held in the recirculation _o

Total dissolved solids (total dissolved solid dose): Figo 4 shows the TDS plotted against TC. The TDS were determined with a “Nalcometer Model MLN”. The meter was standardized using a standard solution of 3000 umho / cm conductivity. the

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TDS readings increased from 6400 umho at 0900 hours 8400 umho at 1600 hours. This shows that solids or putrefactive substances calve away in the system.

Chlorination: Figure 5 shows a comparison of the residual free chlorine in towers before and after the addition of Pluronic L61.

Fig. 5 shows that the residue in the tower in the position of the Chlorinators on 600 # / 24HR can only go as low as 0.2 ppm. this Means that a lot of chlorine is being absorbed by putrefactive substances in the system. On the first day, the HR position rose to # 1,000 / 24 of the chlorinator reduced the residual chlorine in the tower to 0.6 ppm and stayed at 0.3 ppm for several hours This is an indicator that that previous putrefactive substances in the system have been removed; hence the increased residual chlorine in the towers.

Example YII

A single-flow refrigeration system located in a chemical facility in the southeastern United States BC was subjected to this test. America found. The water source was a seepage basin that contained chlorinated sewage from a major city. Before the test, the water was treated with 340 to 344 kg of chlorine as Cl ₂ per day.

Pluronic L61 was fed in slowly at 20 ppm. After 5 1/2

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Stdno had increased the total count of 2 750 000 to 7.3 million "The iron content of the water was increased by 2ppm · The ChIorrückstand fell from 1 ppm to 0, an increased release of silt heat exchange surfaces indicating _o

Dr. Ro./Mü

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Claims (1)

1BERLINS3 IMUNCHENIO Dr. RUSCHKE & PARTNER PATENTANWÄLTE BERLIN - MÖNCHEN PATENT Attorneys η «ει £ 3 * Γ * Tatagiaawa A »» wed: TELEX: 1U7M TELEX: 823717 N 765 patent claims Process for removing and preventing biological silt and sludge formation on the surfaces of technical and industrial cooling systems and the like, characterized in that the water used in the operation of these cooling towers is mixed with at least 0.5 ppm of a propylene oxide-ethylene oxide copolymer made from a polyoxypropylene glycol Polymer with a molecular weight of 1500-2000, which has been reacted with 5 to 30% by weight of ethylene oxide, treated. 2ο Method according to Claim 1, characterized in that it is recognized. that the propylene oxide-ethylene oxide copolymer used is a polyoxypropylene glycol polymer with a molecular weight of about 1750, which polymer has been reacted with 10 to 20 moles of ethylene oxide » ί 3 · Method according to claim 1 or 2, characterized. dai this polyoxypropylene glycol polymer is reacted with the ethylene oxide and a biosidally active amount of a water-soluble oxidizing bioside. Method according to claim 3 _t characterized. that this INSPECTEO 27585AQ water soluble oxidizing biocide is chlorine. & 09828/0696