A polymer useful for drag reduction in hydrocarbon fluids and its preparations

Abstract: Novel polymer for drag reduction in hydrocarbon fluids is disclosed which comprises polymerising a C-12 to C-18 acrylate or methacrylate monomer and an ionic with or without other monomers acting as fillers or additives at a temperature between 20 and 30 o C with constant stirring and separating the resultant polymer. The preparation of the polymers is simple, shear stability is good even at high shear rates, insensitivity to the presence of any other polar solvent and good solubility in almost all the hydrocarbon liquids. The novel polymer reduces friction in the flow of a hydrocarbon fluid by a factor around 5 at concentrations as low as 1 to 25 ppm.

Description: This invention relates to a process for the preparation of a novel polymer useful for drag reduction in hydrocarbon fluids in exceptionally dilute polymer solutions. In the pipeline transportation of fluids, there is drop in fluid pressure due to friction at the pipe wall. Therefore, for a given pipeline, fluid must be transported with sufficient pressure to achieve the desired throughput. Since the pressure drops with the increase in flow rate, more pressure must be applied to increase the flow rate. There are design limitations for a given pipeline to withstand higher levels of pressure. However, when the flow is turbulent in pipelines, the flow rate can be enhanced by the addition of high molecular weight polymeric additives. The role of these additives is to suppress the growth of turbulent eddies, which results in higher flow rate at a constant pumping pressure. The phenomenon is described as drag reduction and can be used to boost flows of crude oil and other hydrocarbon liquids in commercial pipelines. Use of polymeric additives for drag reduction is known. Polymers based on alpha-olefins and other diene monomers have been reported to reduce drag in commercial pipelines. For example, reference is made to US-A-3,559,664 (1971), 3,827,447 (1974), 3,857,402 (1974) and 3,865,124 (1975). The use of polymers based on vinyl monomers and co-monomers has also been reported. Reference is also made to Polymer Engineering and Science, Mid-May, 1980, Vol. 20, No. 7. US-A-3,758,406 describes the use of non-ionic acrylate polymers. Some reports are available in which interpolymer complexes have been used as drag reducers, for example in US-A-4,508,128 (1985). Processes involving use of poly alpha-olefins suffer from the following drawbacks: 1. The shear stability of the polymers is poor. 2. They require elaborate techniques for the manufacture of polymers. 3. The cost of the polymeric additive is high. The use of acrylate polymers for pipeline transportation is not commercially attractive as they are required in higher concentrations for effective drag reduction. Polymers based on intermolecular complexes are reported to perform at concentrations of 250 to 1000 ppm, which are quite high for commercial purposes. Moreover, such polymers are sensitive to the presence of any polar co-solvent, i.e. they may lose their drag reduction activity in the presence of such solvents. The primary advantage of the new polymers of the invention is that they reduce friction in the flow of a hydrocarbon fluid by a factor of around 5 at concentrations as low as 1 to 25 parts per million by weight, giving for instance, drag reduction of 76% in diesel at 25 parts per million by weight. Another advantage is the simple method of producing the polymers i.e. by a polymerisation technique which yields a linear and high molecular weight product. Yet another advantage is the good solubility of the polymer in almost all the hydrocarbon liquids including benzene, toluene, xylene, diesel, kerosene, gasoline and crude oil. A further advantage is the polymers' insensitivity to the presence of any other polar co-solvents, e.g. n-butyl alcohol in amounts of up to 10% by volume. Yet a further advantage is that the polymer is shear stable even at high shear rates. That is, the additive does not lose its drag reduction effectiveness at high shear rates. The object of the invention is to provide a process for the preparation of a novel polymer useful for drag reduction in hydrocarbon fluids which overcomes the drawbacks hereinbefore outlined. Accordingly, the present invention provides a process for the preparation of a new polymer useful for drag reduction in hydrocarbon fluids which comprises polymerising a C-12 to C-18 acrylate or methacrylate monomer and an ionic monomer with or without other monomers acting as fillers or additives, at a temperature between 20 and 30°C with constant stirring and separating the resultant polymer, the amount of acrylate or methacrylate monomer in the polymer being more than 40% by weight and the amount of ionic monomer between 0.05 to 0.1 moles per hundred gram of the polymer. The ionic monomer used in the process of the present invention may for example be selected from the following: sodium acrylate, sodium methacrylate, 4-vinyl sodium benzoate and 4-vinyl pyridinium iodide, chloride or acetate. Any C-12 to C18 acrylate or methacrylate, individually or in combination, can be used. The quantity of the ester monomer in the polymer should be more than 40%. Concentration of the ionic monomer per hundred grams of the polymer can vary between 0.05 moles and 0.1 moles. Monomers acting as fillers or additives may be selected from styrene monomers, acrylate monomers having less than 12 carbon atoms and vinyl monomers. The process of the present invention can be effected by conventional methods. For example, it can be effected by subjecting the monomers to polymerisation in the presence of deionised water, a water soluble initiator and an emulsifier, at a temperature between 20 and 30°C and at a pH between 4 and 6, with agitation. The polymerisation may be affected in the presence of 0.2 to 0.6 per cent by weight of monomers of initiators (such as potassium bromate/sodium sulphate, a combination of potassium persulphate with ferrous sulphate and sodium meta-bisulphite) and 4 to 12 per cent by weight of the monomers of an emulsifier, such as sodium lauryl sulphate or a water soluble non-ionic emulsifier such as Triton X-100®. Other known water soluble redox initiator systems may also be used. The speed of agitation can be maintained between 250 and 400 rpm. The polymer can be isolated by known methods by either heating the emulsion at 60 to 70°C under vacuum or by direct precipitation in a nonsolvent such as methanol. The coagulated polymer is filtered and dried at 60°C under vacuum. The dried polymer is dissolved in a suitable hydrocarbon liquid in concentrations between 5 and 12 grams of polymer per 100 ml of hydrocarbon liquid. The reduced viscosity of 0.5% solution of the polymer should be more than 22 dl/g as determined by Cannon - Ubblehode dilution viscometer, using toluene as solvent at 25°C. The required concentration of polymer in hydrocarbon liquid for effective drag reduction can be between 1 and 25 parts per million by weight of the polymer. The extent of drag reduction by the polymer is evaluated in a pipe loop by measuring pressure drops due to the flow of hydrocarbon liquid and due to that of 1.0 to 25 ppm solution of polymer in hydrocarbon liquid. The invention is described with reference to the following examples: EXAMPLE - 1 45 gram dodecyl methacrylate 50 gram styrene 5 gram sodium methacrylate 275 ml. distilled water 12 gram Triton X - 100® 0.2 gram potassium persulphate 0.2 gram sodium meta-bisulphite 0.001 gram FeSO₄ To a clean 500 ml reactor, all the-above ingredients were charged (except the initiator system) under the positive pressure of nitrogen. After an hour of nitrogen bubbling, the initiator system was introduced to the reactor under agitation. The reaction was continued for 6 hours, maintaining the temperature at 25°C. After the reaction was complete, the polymer was precipitated from the emulsion in cold methanol. The resulting polymer was filtered and dried under vacuum at 60°C for 4 hours. Yield of isolated polymer was more than 98%. The polymer yielded is poly(dodecyl methacrylate - styrene - sodium methacrylate). The polymer was dissolved in toluene in concentration of 10 gram polymer per 100 ml. of toluene by allowing the polymer to swell in the solvent for 7 days. Figure 1 of the drawings accompanying the specification gives the relative performance of drag reduction of a 10 ppm solution of the terpolymer in kerosene. It can be seen from the figure that the polymer retains about 60% of its performance even after ten passes in a 50 cm. long capillary of 3 mm diameter at a typical wall shear-rate of 10,500 per second. The performance of the polymer was evaluated by pumping a solution of known concentration of the polymer of this invention in a hydrocarbon fluid through a 9.3 mm. pipe loop. Pressure drops were monitored-across 30 cm. straight segment of the pipe by means of differential pressure transmitter. Flow rates were measured by means of a mechanical vane type of flow meter. Percent drag reduction was calculated using the following equation: % Drag Reduction = Pressure drop with solvent - Pressure drop with solution Pressure drop with solvent X 100 Pressure drop is measured at a constant volumetric flow rate. The results are tabulated in Table 1. Drag reduction data at various additive concentrations Polymer concentration (ppm) Reynolds number Liquid Drag Reduction 01 27,000 xylene 28 25 11,000 kerosene 53 10 11,000 kerosene 34 05 28,000 diesel/kerosene 30 25 28,000 diesel/kerosene 76 EXAMPLE - 2 41.75 gram dodecyl methacrylate 50 gram styrene 8.25 gram vinyl pyridinium acetate 275 ml distilled water 12 gram Triton X - 100® 0.2 gram potassium persulphate 0.2 gram sodium meta-bisulphite 0.001 gram FeSO₄ The polymer yielded is poly(dodecyl methacrylate - styrene - vinyl pyridinium acetate). The procedure for the preparation of the polymer is essentially the same as described in Example 1. Drag reduction characteristics of the polymer were studied by the method explained in Example 1 and the results are tabulated in Table 2. Drag reduction data at various additive concentrations Polymer concentration (ppm) Reynolds number Liquid Drag Reduction 05 28,000 diesel/kerosene 34 10 27,000 xylene 38 10 11,000 kerosene 34

Claims: A process for the preparation of a polymer useful for drag reduction in hydrocarbon fluids which comprises polymerising a C-12 to C-18 acrylate or methacrylate monomer and an ionic monomer, with or without other monomers acting as fillers or additives, at a temperature between 20 and 30°C with constant stirring and separating the resultant polymer, the amount of acrylate or methacrylate monomer in the polymer being more than 40% by weight and the amount of ionic monomer between 0.05 to 0.1 moles per hundred gram of the polymer. The process as claimed in claim 1 wherein the ionic monomer is selected from sodium acrylate, sodium methacrylate, 4-vinyl sodium benzoate and 4-vinyl pyridinium iodide, chloride or acetate. The process as claimed in claim 1, wherein the polymerisation is effected using, as initiator, a combination of potassium persulphate, ferrous sulphate, and sodium meta-bisulphite. The process as claimed in claim 3, wherein the amount of initiator ranges from 0.2 to 0.6 per cent by weight of monomer. The process as claimed in claim 1, wherein the polymerisation is effected using sodium lauryl sulphate or a water soluble non-ionic emulsifier. The process as claimed in claim 5, wherein the amount of emulsifier ranges from 4 to 12 per cent by weight of monomer. The process as claimed in claim 1, wherein the polymerisation is effected at a pH of 4 to 6. The process as claimed in claim 1, wherein the monomers acting as fillers or additives are selected from styrene monomers, acrylate monomers having less than 12 carbon atoms and vinyl monomers. A polymer, which is the polymerised product of a C-12 to C-18 alkyl acrylate or methacrylate monomer and an ionic monomer, with or without other monomers acting as fillers or additives. The use of a polymer according to claim 9 as a drag reduction additive for hydrocarbon fluids. The use according to claim 10 of 1 to 25 parts per million of the polymer as a drag reduction additive in the transport of a hydrocarbon fluid through a pipeline.

Inventors: MALIK SANJAY, MASHELKAR RAGHUNATH ANANT, SHINTRE SATISH NARAYAN, MALIK, SANJAY, MASHELKAR, RAGHUNATH ANANT, SHINTRE, SATISH NARAYAN, MALIK, SANJAY, NATIONAL CHEMICAL LABORATORY, MASHELKAR, RAGHUNATH ANANT, NATIONAL CHEMICAL, SHINTRE, SATISH NARAYAN, NATIONAL CHEMICAL
Applicants: COUNCIL SCIENT IND RES, COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH
Application year: 1990
Main classification: C08F220
IPC codes: C08F220, C09K3