CS254228B1 - Additive to aqueous medium - Google Patents

Abstract

Reduction of hydraulic resistance, or pressure loss due to friction of the aqueous medium is achieved with an additive of 1.1G'5 to 0.3% by mass. (1. . IQ-3 to 5.10-2% by weight) of partially saponifiable polyvinyl acetate with a degree of hydrolysis of 45 to 99.9% mol. (60 to 92% mol.), possibly with stabilizer additives (bicides, anti-corrosion additives). So with an additive of 1.5.10-2% wt. of partially saponified polyvinyl acetate with a degree of hydrolysis of 88% mol. into the cooling water and compared to pure water, the average value of the frictional pressure loss reduction coefficient is up to 62%. The depressant additive is mainly used in closed cooling systems in the energy industry of practically all industrial sectors, but also in the air industry and in fire protection.

Description

The invention relates to the use of an additive of a synthetic polymer or polymers to an aqueous medium to reduce pressure losses due to friction and/or hydraulic resistance, thereby significantly reducing the energy requirement for pumping them, or suppressing the dissipation of energy in a turbulent flow of water or aqueous solutions.

The Thomson effect or the reduction of pressure losses due to friction of flowing liquids, especially flowing water and aqueous solutions, has been intensively studied for some time now with the application of polymer additives (Soo S. L.: Hydrodynamics of multiphase systems. Mir Publishing House, Moscow /1971/; Goldstein R. J. et al.: Ind. Eng. Chem. Fundam. 8, 19Θ9, p. 498;

Wang Chien-bang: Ind. Eng. Chem. Fundam 11, 1972, p. 546). Experimental research was carried out over a wide range of types and concentrations of polymer additives, their molar mass, the influence of temperature and pH of solutions, including the investigation of mechanical degradation of applied polymers (Patterson GK et al.: The Physics of Fluids 20, 1977, p. 68; White DJ et al.: AICHE J„ 21, 1975, p. 1 027; Sedov LJ et al.: Izv. AN SSSR, MŽB Moscow 1974, p. 205; Frenkiel FN et al.: Structure of Turbulence and Drag Reduction, Am. Inst.. of Physics, New York 1977), especially dissolved in water. It is also known (Virk PS: AICHE J„ 21, 1975, p. 625; Seyer F. A, et al.: ibid. 15, 1969, p. 426) that the reduction of losses pressure loss by friction of diluted aqueous polymer solutions (compared to pure water) is observed only in the region of transient turbulent flow character, depending on the concentration and molar mass of the additive. Such an effect on reducing pressure loss by friction of flowing water with polymer admixture in comparison with flowing water alone has polyglycols or polyethylene oxide with molecular weight of the order of IO ^-5 and higher (Kutateladze

S.S., Mironov Β. P.: Experimental investigation of rigorous turbulent theories, p. 60. Nauka, Novosibirsk 1975; Schowalter W.R.: Mechanlcs of Non-Newtonian Fluids, p. 244. Pernamon Press, Oxford 1978; Sedov

L. I. and others: On calculations of turbulent boundary layers with small additions of polymers, p. 205, Nauka, Moscow 19741. Next, polyacrylamide and partially hydrolyzed nolvacramide, as well as guar gum (Nikitin I. K. and others: Profile of the speed and resistance of friction in turbulent rotation. p. 93. Gidromechanika. Moscow 1971). Then carboxymethylcellulose with hydroxyethylcellulose in concentrations of 0.1 to 0.5 wt. % (Lodes A., Zaliherová A.. Hudáčková H.: Proceedings of the 4th National Conference on Fluid Relativity in Industrial Practice, p. 177 to 182. Velké Karlovice 1981).

However, the above additives or depressants for aqueous media require polymers with extremely high molecular weights, the production of which is technically more demanding, or even higher concentrations. Also, due to the degradation of polymer additives, their "lifetime" is significantly reduced, their effectiveness changes, etc.

However, the essence of the present invention is the use of partially saponified polyvinyl acetate with a hydrolysis input of 45 to 99.9 mol%, preferably with a degree of hydrolysis of 60 to 92%, in a total dry matter amount of 1. . 10 ^-5 to 0.3 wt%, preferably 1. . 10 ^-3 to 5. 10 ~ ^z wt%, optionally additionally with a water-soluble system stabilizer, preferably a water-soluble biocide and/or anticorrosion agent, as an additive to an aqueous medium, preferably to cooling water in heat exchangers and in circulating cooling systems, to reduce pressure losses due to friction and/or hydraulic resistance.

The technical progress of using the additive for aqueous media according to this invention consists not only in finding a new synthetic polymer additive for water and aqueous solutions to reduce hydraulic resistance, pressure losses due to friction during their transport, but also in the extremely high effect of partially saponified polyvinyl acetate and thus in reducing the consumption of electrical energy during application, both in comparison with known water-soluble polymers, even with the required extremely high molecular weights, used for similar purposes, and with pure polyvinyl alcohol. Furthermore, the relatively significant stability of the new additive, during application, practical insensitivity to other possibly necessary additives for cooling systems and technical availability.

When choosing partially saponified polyvinyl acetate, it is advisable to pay attention mainly to the achieved degree of hydrolysis, which cannot be below 45 mol %: for reasons of poor solubility or practically insolubility in water. Pure polyvinyl alcohol itself has a similar, low efficiency. It is most suitable to choose partially saponified polyvinyl acetate with a degree of hydrolysis in the range of 60 to 92 mol %. For high efficiency, on the one hand, water solubility is required, but on the other hand, the presence of hydrophobic acetyl groups is also required. Partially saponified polyvinyl acetate can be applied both in the form of dried, i.e. partially saponified polyvinyl acetate itself, and also in the form of an aqueous or aqueous-methanolic solution, or aqueous-glycol solutions. It is suitable mainly in the form of an aqueous solution or in the form of an aqueous-methanolic solution, with possible admixtures of methyl acetate.

Data on the concentrations of partially saponified polyvinyl acetate in treated waters or in aqueous media are calculated from the weight of dry matter or pure polymer and are in the range of 1. 1CV ⁵ to 0.3 wt. %. However, the highest efficiency is achieved in the range of 1.10 ^-3 to 5.10~ ² wt. %.

The term aqueous medium refers to water as such, spring, river, demineralized, etc., but especially recirculated through heat exchangers and cooling stations, and aqueous solutions of inorganic and/or organic compounds. As a rule, undesirable impurities in such aqueous media are colloidal particles and fine suspensions, which can adsorb partially saponified polyvinyl acetate on their surface and thereby reduce the effective concentration of the additive (depressant).

To increase the service life and reproducibility of the reduction of hydraulic resistance and pressure losses due to friction, it is advisable to additionally apply additives of known biocides, since microorganisms and enzymes are usually the main cause of degradation of polymer additives in water. Furthermore, anticorrosive additives, antioxidants (hydrazine hydrate), or water-soluble dyes, etc. When using the depressant according to this invention, it is possible to combine additives of partially saponified polyvinyl acetate with other, known polymers and copolymers, reducing pressure losses, friction and hydraulic resistance of aqueous media.

Additives to flowing water, or cooling voids. can be added once or in parts, or continuously. Continuous addition is considered especially in cases of non-returnable water flow, such as when using water for fire-fighting (greater availability of cooling water) purposes or irrigation. In such an application, growth stimulants, compounds of microelements — bioelements, pesticides, etc. can also be added to the water.

Further details on the possible uses of the depressant according to the invention, as well as further advantages, are apparent from the examples.

Example 1

In the tube exchanger, water vapor condenses with a pressure of 0.2 MPa. The cooling water is heated from 20 to 40 °C. 63,700 kg of water/h flows in the exchanger with a condensation of 3,636 t of steam/h. There are 40 parallel tubes in the exchanger through which water flows. The tubes have a diameter of 26 X 2 mm and a length of 3 m. The water is pumped by a centrifugal pump with an efficiency of 42%. After adding to the water 8.7.10 ^-4 wt. % calculated on the weight of the water of the aqueous medium of partially saponified polyvinyl acetate, with a degree of hydrolysis of p-polyvinyl acetate of 52.5 mol. % (with 46% of acetate groups) in the form of its aqueous-methanolic solution with a concentration (dry basis) of 8.7 wt. %, i.e. in an amount of 1.10 ^-2 wt. %. the pressure loss coefficient is 18%.

The Reynolds criterion in the pipes is 26,900. The coefficient of pressure loss due to water friction is 0.0245 and that of the solution with polymer — partially saponified polyvinyl acetate is 0.0201. The height lost by friction in the case of water is 3.73 m; pump power 0.066 kW; required input 565.2 kWh and electricity consumption 4.88.10 ⁷ kW-h/year (year).

In a cooling water solution with the addition of

8.7.10 ^{- 4} % by weight of partially saponified polyvinyl acetate, the friction loss height in the case of solution flow is 3.05 m; pump power 0.054 kW; required power 464.4 kWh and the electricity consumption is thus 4.01.10' kWh/year. The annual electricity saving is 8.7. 10® kWh, i.e. 3.132. 10® MJ in the case that the above aqueous solution and the amount of partially saponified polyvinyl acetate with a degree of hydrolysis of 52.5 mol. % are used instead of water alone.

A similar result is achieved with water containing, in addition to 8.7.10 ^-4 wt. % of partially saponified polyvinyl acetate with a degree of hydrolysis of 52.5 mol. % or more, 0.1 wt. % of sodium p-cumylphenolate as a biocide.

Example 2

In a countercurrent tube-in-tube heat exchanger, 0.1 m ³ /min of benzene is to be cooled from a temperature of 78 °C to a temperature of 26 °C. It is cooled by water, the inlet temperature of which is 20 °C and the outlet temperature is 40 °C. The outer tube of the cooler has a diameter of 82 X 2 mm and the inner tube has a diameter of 36 X 2 mm. The benzene flows in the inner tube. The thermal conductivity of the tube material is

34.9 w . m ^-1 . K ^-1 . Instead of water alone, water with an additive is used for cooling

1.6.10 ^{- 3} % by weight of partially saponified polyvinyl acetate, with a degree of hydrolysis of 88 mol. % (with 14.5% acetate groups), from which an aqueous solution prepared with a concentration of 4% by weight at a temperature of 20 °C is 13 mPa . . s in the form of an aqueous solution with a concentration (dry matter) of 15.47% by weight (Sloviol R).

To cool benzene with a flow rate of 5,070 kg. h ^-1 , the consumption of cooling water according to the heat balance is 5,670 kg. h ^-1 . The average temperature of benzene is 52 °C and water 30 °C. The reduction in pressure losses due to friction is 24%.

The volumetric flow rate of water is 1.58.10 ^-3 m ³ . . s ^-1 , the water velocity is 0.731 m . s ^-1 , the equivalent diameter is 0.026 m. The value of the Re criterion is 23,600. The length of the pipe from the heat transfer rate equation is 52 m, while the heat flux is 131,884 W and the logarithmic mean temperature in the exchanger is 17.4 K.

The pressure losses calculated according to Darcy's equation for water (if the coefficient of pressure losses due to water friction is determined according to Blasius' equation) have a value of 0.0254.

In the case of using cooling water containing 1.6.10 ^-3 % by weight of the said partially saponified polyvinyl acetate, the coefficient of frictional pressure loss is 0.0193.

The required power for pumping cooling water is 667,008 kWh/year; in the case of pumping a solution of water with the above-mentioned partially saponified polyvinyl acetate, it is 506,883 kWh/year.

The energy savings when using the above water solution for cooling are 160,175 kWh/year, or 576,630 MJ/year.

Example 3

From the cooling water tank, it is supplied to individual cooling points through a 1.2 km long pipeline with an internal diameter of 150 mm. Water consumption is 4.10 ³ m ³ . s ¹ . The average water temperature is 20 ^C C. The cooling water is treated by adding 8.7.10“ ⁴ % by weight of partially saponified polyvinyl acetate with a degree of hydrolysis of 52.5 % by weight, in the form of a water-methanol solution with a concentration (dry matter) of 8.7 % by weight specified in Example 1. At a given solution temperature, the coefficient of reduction of the friction pressure loss coefficient is 9.4 %.

At a volumetric flow rate of 4.10 ³ m ³ .s ^_1 the velocity in the pipe is 0.226 m. s“ ¹ . The Reynolds criterion is 33,970. Then the coefficient of frictional pressure loss for water is 0.0232 and for cooling water containing 8.7.10~ ⁴ % by weight of the said partially saponified polyvinyl acetate is 0.0210.

The required pump power for water is 67,807 kWh and for cooling water containing partially saponified polyvinyl acetate is 61,308 kWh.

The electricity saving is 8,499 kWh/h, or 202.14.10 ^e MJ/year.

Example 4

In the same system as in example 3, treated water is used by adding 1.547.10 ² percent by mass. of partially saponified polyvinyl acetate with a degree of hydrolysis of 88% mol., specified in example 2, in the form of an essentially aqueous solution (only admixtures of methanol and methyl acetate) with a concentration (dry matter) of 15.47 wt.%.

With an additive amount of 1.547. IO ^-2 % by weight of partially saponified polyvinyl acetate into the cooling water, the average value of the coefficient of reduction of pressure losses by friction of the treated water is up to 62%.

The volumetric flow rate of water, or treated water, is 4 . IO“ ³ m ³ . s ¹ ; velocity 0.226 m . . s ¹ ; viscosity of treated water 1.03 . IO“ ³ Pa . s ; Reynolds criterion 32,895.

The pressure loss coefficient for pure water is 0.0235 and for water treated with 1.547% by weight of partially saponified polyvinyl acetate is 0.009.

The required power for a pump for clean water is 69,212 kWh; for pumping treated water, 26,192 kWh.

The hourly energy saving is 43,020 kWh, ie 1,338.10 ⁶ MJ/year.

Example 5

In the same system as in Example 3, treated water is used with an additive of ^1.102 wt. percent of almost completely saponified polyvinyl acetate with a degree of hydrolysis of 99.7 mol.%, i.e. with an additive of 1.102 ^wt . percent, calculated on water, of practically pure polyvinyl alcohol.

At the stated concentration of polyvinyl alcohol in the treated water compared to pure water, the average coefficient of reduction of pressure losses due to friction is 2.2%. The volume flow of water is 4.10 ³ m ³ . s“ ¹ ; velocity 0.226 m. s ¹ ; the viscosity of the treated solution is 1.04 . 10 ³ Pa . with a Reynolds criterion of 32,500.

The coefficient of frictional pressure loss for clean water is 0.0236 and for treated water 0.0230. The required pump power for clean water is 69,212 kWh and for treated water 67,524 kWh.

The hourly electricity savings are 1,597 kWh, which is 49.67 MJ/year.

It follows from the above that practically pure polyvinyl alcohol, unlike partially saponified polyvinyl acetate, causes only a small reduction in pressure losses of flowing water due to friction and thus only a small energy saving.

Claims (1)

EXAMPLE 3 From a cooling water reservoir, individual cooling sites are supplied with pipes of 1.2 km in length with a diameter of 150 mm. Water consumption is 4.ID-3 m3. s-1. The average water temperature is 20 CC. The cooling solution is adjusted by the addition of 8.7% by weight of a 4% by weight saponified polyvinyl acetate to a degree of hydrolysis of 52.5% by weight in the form of a water-methanolic solution of 8.7% by weight. as specified in Example 1. At a given solution temperature, the coefficient of friction loss reduction is 9.4%. With a flow rate of 4.10 ~ 3 m3.s_1, the line speed is 0.226 m. S_1. The Reynolds criterion is 33,970. Thereafter, the pressure-friction coefficient for water is 0.0232 and the chilled water is 8.7.10-4% by weight. of said partially hydrolyzed polyvinyl acetate is 0.0210. The required water pump capacity is 67,807 kWh and 61,308 kWh for cooling water with partially saponified polyvinyl acetate. Thus, electricity savings are 8,499kWh / h, respectively. 202,14.10e MJ / y. EXAMPLE 4 In the same system as in Example 3, treated water was added by adding 1.547.10 < 2 > a partially saponified polyvinyl acetate having a degree of hydrolysis of 88% mole specified in Example 2 as a substantially aqueous solution (only methanol and methyl acetate) of 15.47% by weight. With an additive amount of 1.547. 10% by weight of the comparatively saponified polyvinyl acetate in the cooling water is the mean value of the loss of pressure loss by friction of the treated water up to 62%. Volume flow of water, resp. modified water is 4.ID-3 m3. s-1; speed 0.226 m .. s_1; water viscosity of 1.03 to 10 Pa. with; Reynolds criterion 32 895. The pressure loss coefficient for pure water is 0.0235 and the treated water additive is 1.547%. partially saponified polyvinyl acetate 0.009. The required power per pump for clean water is 69,212 kWh; for the treatment of treated water 26 192 kWh. Hourly energy saving is 43 020 kWh, t. j. 1 338.106 MJ / y. Example 5 In the same system as in Example 3, treated water is added with 1.10. almost complete saponified polyvinyl acetate with a degree of hydrolysis of 99.7% molar, i.e. with additive 1.10 of 2% by weight. calculated on water virtually pure polyvinyl alcohol. At the present concentration of polyvinyl alcohol in the treated water compared to the purification, the average coefficient of reduction of the pressure drop is 2.2%. The volume flow of water is 4.00-3 m3. s_1; speed 0,226m. s “1; the viscosity of the conditioned solution is 1.04. ID “3 Pa. s and Reynolds criterion 32 500. Pressure loss coefficient by friction of pure water is 0.0236 and treated water 0.0230. The required power to the clean water pump is 69,212 kWh and 67,524kWh for treated water. Hourly electricity savings are 1 597 kWh, which is 49.67 MJ / y. As a result, virtually pure polyvinyl alcohol, unlike partially hydrolyzed polyvinyl acetate, causes a slight reduction in water-thawing pressure losses and thus a low energy saving. REDM e τ Use of partially saponified polyvinyl acetate with a degree of hydrolysis of 45 to 99.9% mole, preferably with a degree of hydrolysis of 60 to 92% mole, in a total amount of 1.10 to 5 to 0.3% by weight, s preferably 1.10 to 3.10 with a water-soluble system stabilizer, preferably a water-soluble biocide and / or anti-corrosion agent, as an additive to the aqueous medium, preferably to the cooling water in the water. heat exchangers and in circulating cooling systems, to reduce pressure by friction and / or hydraulic support. Ssverografla, n. P. 7, Most Csna 2.40 KEs