Process for producing aqueous polyacrylamide solutions

A process for producing an aqueous polyacrylamide solution by polymerizing an aqueous solution comprising at least acrylamide thereby obtaining an aqueous polyacrylamide gel and dissolving said aqueous polyacrylamide gel in water, characterized in that the process comprises at least the following steps:

• [0] Hydrolyzing acrylonitrile in water in the presence of a biocatalyst capable of converting acrylonitrile to acrylamide, thereby obtaining an aqueous acrylamide solution at a location A,
• [1] radically polymerizing an aqueous monomer solution in the presence of suitable initiators for radical polymerization under adiabatic conditions at a location A, wherein
• the aqueous monomer solution comprises at least water and 15% to 24.9% by weight—relating to the total of all components of the aqueous monomer solution—of water-soluble, monoethylenically unsaturated monomers at a location A, wherein said aqueous solution comprises at least the aqueous acrylamide solution prepared in course of step [0], and
• the polymerization is performed in a transportable polymerization unit P comprising a cylindrical upper part having a length of 4 m to 6 m and a diameter from 1.5 m to 2.5 m, a conical part at its lower end having a conus angle from 15° to 90°, feeds for the aqueous monomer solution, a closable bottom opening having a diameter from 0.2 to 0.8 m, and means allowing to deploy the unit P in a vertical manner,
• the aqueous monomer solution has a temperature T1 not exceeding 30° C. before the onset of polymerization, and
• the temperature of the polymerization mixture raises in course of polymerization—due to the polymerization heat generated—to a temperature T2 of at least 45° C.,
• thereby obtaining an aqueous polyacrylamide gel which is hold in the transportable polymerization unit,
• [2] transporting the transportable polymerization unit filled with the aqueous polyacrylamide gel from location A to a different location B,
• [3] removing the aqueous polyacrylamide gel from the transportable polymerization unit through the closable bottom opening at the location B, and
• [4] comminuting and dissolving the aqueous polyacrylamide gel in an aqueous liquid at the location B, thereby obtaining an aqueous polyacrylamide solution.

A process for producing an aqueous polyacrylamide gel by polymerizing an aqueous solution comprising at least acrylamide, wherein the process comprises at least the following steps:

• [1] Radically polymerizing an aqueous monomer solution in the presence of suitable initiators for radical polymerization under adiabatic conditions, wherein
• the aqueous monomer solution comprises at least water and 5% to 45% by weight—relating to the total of all components of the aqueous monomer solution—of water-soluble, monoethylenically unsaturated monomers at a location A, wherein said water-soluble, monoethylenically unsaturated monomers comprise at least acrylamide, and
• the polymerization is performed in a transportable polymerization unit P comprising a cylindrical upper part, a conical part at its lower end, feeds for the aqueous monomer solution, a closable bottom opening, and means allowing to deploy the unit P in a vertical manner,
• thereby obtaining an aqueous polyacrylamide gel which is hold in the transportable polymerization unit.