Production method for producing water-absorbing polymer particles and belt dryer
AssigneeBASF SE
InventorsGerald Grünewald, Rüdiger Funk, Matthias Weismantel, Karl Possemiers
Life of this patent
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Abstract
A production process for production of water-absorbing polymer particles including drying an aqueous polymer gel in a belt drier with a conveyor belt. The belt drier is formed with a drier setup substantially comprising the conveyor belt and an air recycling conduit downstream of the drier setup for air recycling, where recycled air is withdrawn from the drier setup and fed back to the drier setup via the air recycling conduit.
Claims21
A production process for production of water-absorbing polymer particles, where the production process has the following steps:
- polymerizing an aqueous monomer solution or suspension for production of an aqueous polymer gel,
- drying the aqueous polymer gel in a belt drier with a conveyor belt, by accommodating the aqueous polymer gel on the conveyor belt and conveying the aqueous polymer gel on the conveyor belt in a conveying direction (C),
- crushing and/or grinding the dried polymer gel to give water-absorbing polymer particles, where
- for drying:
- the belt drier comprises a drier setup (101) substantially comprising the conveyor belt and an air recycling conduit (350) downstream of the drier setup (101) for air recycling, where recycled air (RL) is withdrawn from the drier setup (101) and fed back to the drier setup (101) via the air recycling conduit (350), and
- the air recycling conduit (350) has an air withdrawal conduit (340) formed between an upstream intake section (EA) relative to air flow direction in the drier setup (101) and a downstream outlet section (AA) relative to air flow direction in the air recycling conduit (350), characterised in that
- the air withdrawal conduit (340) has an air withdrawal line (341) and air recycling line (354) with at least one filter (353), heat exchanger (352) and/or ventilator (351),
- a flow cross section in at least one air-removing section (A, A1, A2, A3, A4) of the air withdrawal conduit (340) has an increase in cross section (Q, Q1, Q2, Q3, Q4), where the increase in cross section increases a cross section of the air-removing section (A, A1, A2, A3, A4) of the air withdrawal conduit in such a way that
- the recycled air (RL) at least in the air-removing section (A, A1, A2, A3, A4) of the air withdrawal conduit (340) is removed at a reduced flow rate, and/or
- the recycled air (RL) at least in an intake section (EA) of increased cross section in the air withdrawal conduit (340) is removed at a reduced intake rate.
A belt drier that is a circulation belt drier comprising an air circulation belt drier (1000) for guiding circulating air (UL), for drying an aqueous polymer gel and conveying the polymer gel on a conveyor belt, wherein
- the belt drier takes the form of an air circulation belt drier (1000) formed so as to guide circulating air with a drier setup (101) substantially comprising the conveyor belt and an air recycling conduit (350) connected to the drier setup (101), where recycled air (RL) is withdrawn from the drier setup (101) and fed back to the drier setup (101) via the air recycling conduit (350), and
- the air recycling conduit (350) has an air withdrawal conduit (340) formed between an upstream intake section (EA) relative to air flow direction in the drier setup (101) and a downstream outlet section (AA) in the air recycling conduit (350), wherein
- the air withdrawal conduit (340) has an air withdrawal line (341) and air recycling line (354) with at least one filter (353), heat exchanger (352) and/or ventilator (351),
- a flow cross section in at least one air-removing section (A, A1, A2, A3) of the air withdrawal conduit (340) has an increase in cross section (Q, Q1, Q2, Q3, Q4), wherein the increase in cross section increases a cross section of an air-removing section (A, A1, A2, A3) of the air withdrawal conduit (340) in such a way that
- the recycled air (RL) in the air-removing section (A, A1, A2, A3) of the air withdrawal conduit (340) is removed at a reduced flow rate, especially at a reduced flow rate lower than at an upstream cross section of the air withdrawal line relative to air flow direction and/or than an intake rate in the intake section (EA) and/or
- the recycled air (RL) at least in an intake section (EA) of increased cross section in the air withdrawal conduit (340) is removed at a reduced intake rate.
Dependencies are inferred from the claim text.