DE19501145A1 - Use of alkyl polyglycosides as a friction reducer - Google Patents

Abstract

The invention relates to the use of alkyl polyglycosides as antifriction agents (flow promoters or drag reducers) for aqueous systems in turbulent flow in the temperature range from 5 to 60{C.

Description

The invention relates to the use of alkyl polyglycosides as Rei Exercise reducer (flow accelerator or drag reducer) for turbulent flowing aqueous systems.

By using friction reducing additives, the pressure loss and thus reducing the required pump energy in flow circuits or at a given pressure drop, the volume flow rate is increased the. The latter also applies to open flow channels such. B. sewage channels in which the volume flow z. B. for Eliminating bottlenecks during heavy rainfall can be increased. Egg on the one hand, it can save pump energy, others on the one hand can eliminate bottlenecks on an expensive new investment tion for larger pipe systems.

Known friction reducers are water-soluble, long-chain or high moles kular polymers (DE 28 07 709 A1) or cationic surfactants (EP 0 097 926 B2) or nonionic surfactants of the ethoxylated fatty alcohol type (U.S. Patent 3,961,639).

However, polymers are subject to a mechanical and thermal bean irreversible degradation caused by stress, d. H. Chain removal. she thereby quickly lose their friction-reducing effect and are therefore especially not suitable for use in closed systems.

Cationic surfactants that reduce friction are quaternary re ammonium compounds. Their use is ecological properties (biodegradability, toxicity to water organisms) controversial and even led to use in Sweden prohibition [tenside surf. Det. 30 (1993) 3, 174].

The classic anionic surfactants (ethoxylated fatty alcohols) show only at relatively high usage concentrations of over 5,000 wppm (weight parts per million) with high electrolyte concentrations 1% by weight has a friction-reducing effect (US Pat. No. 3,961,639).

So the task was to find ecologically harmless additives which has a friction-reducing effect at low concentrations cause aqueous systems.

Surprisingly, it was found that alkyl polyglycosides (APG) relatively low concentrations a friction reduction in aqueous Systems. The invention therefore relates to the use of nonionic surfactants as friction reducers in aqueous systems, because characterized in that alkyl polyglycosides as nonionic surfactants be used.

Alkyl polyglycosides are surfactants that are made exclusively from renewable Raw materials (starch or sugar and vegetable oils) are produced. A more detailed description of the production and characterization of Al kylpolyglycosiden can be found e.g. B. in DE-OS 19 43 689 or U.S. Patent 3,839,318.

Alkyl polyglycosides are considered to be extremely biodegradable [surfactants Surf. Det. 30 (1993) 2, 116]. Your toxicity data are far from harmless licher than that of many other surfactants. Since they are fully re-grown send raw materials, they are characterized by overall excellent environmental behavior.

The alkyl glycosides follow the formula I.

RO- (G) _DP -H (I),

in the R for an aliphatic, linear or branched alkyl and / or Alkenyl radical with 8 to 18 carbon atoms, (G) for a glycose unit with 5 or 6 carbon atoms and D.P. represents a number from 1 to 5.

The glycose unit can be derived from aldoses or ketoses. Because of the better reactivity is preferably the reducing acting saccharides, the aldoses, used. Because of their easy ver Of these, glucose is particularly preferred.  

Particularly suitable for reducing friction are alkyl polygly coside with hydrophobic chains with 8 to 16 carbon atoms, especially preferably 12 to 14 carbon atoms in question. The degree of glycosidation D.P. (Degree of Polymerization) can preferably be 1.1 to 3, especially preferably 1.1 to 1.5.

It was surprisingly found that from relatively low concentrations trations of 300 wppm (weight parts per million), i.e. 0.03% by weight friction-reducing effect occurs in aqueous systems. Thus lies the minimum concentration required to reduce friction Lich lower than the classic nonionic surfactants, where at least 0.5% by weight with a high electrolyte content is required are. As a rule, concentrations of 500 to 2,000 wppm (0.2% by weight) are set. Higher concentrations up to e.g. B. 10,000 wppm also bring about a reduction in friction, but are in generally justifiable in special cases for economic reasons.

It has also been found that unlike the ethoxylated fat alcohols no addition of electrolytes to the water is required to to obtain a friction-reducing effect with alkyl polyglycosides, or that the effect at both low and high electrolyte levels ten occurs. An effect occurs both in almost completely desalted water (electrical conductivity approx. 100 µS / cm) as well as in salt water with 3 wt .-% sodium chloride.

The temperature of the aqueous systems can be 5 to 60 ° C. Preferential the temperature should be in the range of 10 to 40 ° C. Of the pH of the solution can be 3 to 13, preferably 4 to 10, especially before trains 5 to 8.

Fig. 1 shows resistance characteristics of water (generally Newtonian liquids) and water with 500 and 2,000 wppm APG-1.4 / 12. The first number indicates the (average) degree of glycosidation, the second number the (average) alkyl chain length. The measurements were carried out in a pipe apparatus (inner diameter 8 millimeters, pipe length 2 meters) at 30 ° C. Resistance reductions of up to 70% are achieved, ie the pressure loss is only 30% of the value for the additive-free water flow.

Fig. 2 shows resistance characteristics for a concentration of 1000 wppm at different temperatures.

The loss of effectiveness indicated in Figs. 1 and 2 at high flow velocities and / or high temperatures are reversible. In the case of an appropriately loaded solution, after reducing the load, ie reducing the flow rate and / or lowering the temperature, the friction-reducing effect resumes, as was also found for the cationic friction-reducing surfactants (EP 0 097 926 B2).

Claims (10)

1. Use of nonionic surfactants as a friction reducer in tur bulent flowing aqueous systems, characterized, that alkyl polyglycosides are used as nonionic surfactants. 2. Use of nonionic surfactants according to claim 1, characterized, that alkyl polyglycosides with chain lengths with 8 to 16 carbon atoms Men can be used in the alkyl chain. 3. Use of nonionic surfactants according to claim 1, characterized, that alkyl polyglycosides with chain lengths of 12 to 14 carbon atoms are used in the alkyl chain. 4. Use of nonionic surfactants according to at least one of the Claims 1 to 3, characterized, that the alkyl polyglycoside has a degree of glycosidation of 1.1 to 3. 5. Use of nonionic surfactants according to at least one of the Claims 1 to 3, characterized, that the alkyl polyglycoside has a degree of glycosidation of 1.1 to 1.5 Has. 6. Use of nonionic surfactants according to at least one of the types sayings 1 to 5, characterized, that the alkyl polyglycoside is an alkyl polyglucoside.   7. Use of nonionic surfactants according to at least one of the types sayings 1 to 6, characterized, that the concentration of the alkyl polyglycside is 300 to 10,000 wppm (0.03 to 1% by weight). 8. Use of nonionic surfactants according to at least one of the types sayings 1 to 6, characterized, that the concentration of the alkyl polyglycoside is 500 to 2,000 wppm (0.05 up to 0.2% by weight). 9. Use of nonionic surfactants according to at least one of the Claims 1 to 8, characterized, that the temperature is 5 to 60 ° C. 10. Use of nonionic surfactants according to at least one of the Claims 1 to 8, characterized, that the temperature is 10 to 40 ° C.