摘要:
A field device for process instrumentation having an interface for connecting a two-wire cable and for outputting measurement values, wherein the interface comprises a series circuit having a transistor circuit by which the loop current is adjustable as a function of a control signal, a power supply, and a device by which the loop current can be captured as an actual value that is fed by a first feedback coupling to a regulator having integrated behavior. The regulator compares the actual value to a target value, and generates a control signal for the transistor circuit. The actual value is fed by a second feedback coupling to a summation point as a compensation signal for generating an input signal for the transistor circuit as a function of the control signal and the compensation signal to suppress interference coupled into the two-conductor line.
摘要:
The invention relates to a process for the preparation of mechanically and osmotically stable, high-capacity strongly acidic cation exchangers having a particle size of ≧0.1 mm by sulphonation of gel-like or porous bead polymers with sulphuric acid without the use of inert chlorine-containing swelling agents and/or of comonomers based on acrylonitrile. According to the invention, such strongly acidic cation exchangers can be prepared by sulphonation of gel-like and porous bead polymers, prepared by copolymerization of styrene and divinylbenzene having a crosslinker content of up to 65% by weight of divinylbenzene with and without inert composition, with 80-96% strength sulphuric acid at temperatures of 125-180° C. and a reaction time of up to 20 h. According to the novel process, strongly acidic cation exchangers can be prepared without the use of the inert chlorine-containing environmentally harmful swelling agent 1,2-dichloroethane, with quality features and material characteristics identical or similar to products produced by the conventional processes.
摘要:
A field device for process instrumentation having an interface for connecting a two-wire cable and for outputting measurement values, wherein the interface comprises a series circuit having a transistor circuit by which the loop current is adjustable as a function of a control signal, a power supply, and a device by which the loop current can be captured as an actual value that is fed by a first feedback coupling to a regulator having integrated behavior. The regulator compares the actual value to a target value, and generates a control signal for the transistor circuit. The actual value is fed by a second feedback coupling to a summation point as a compensation signal for generating an input signal for the transistor circuit as a function of the control signal and the compensation signal to suppress interference coupled into the two-conductor line.
摘要:
The invention relates to processes for the preparation of free-flowing end products of strongly acidic cation exchangers. In the case of the strongly acidic cation exchangers prepared by the processes described in Patent Application P 195 48 012.0, the particle beds of the end products are not free-flowing. By additions of wetting agents or water-soluble initiators or surfactants in the polymerization stage or after the filtration of the end product and/or process engineering means, a permanent or temporary free flowability of the particle beds of the strongly acidic cation exchangers is achieved using the following processes. 1. By additions of known wetting agents in amounts of 0.25 g/l of aqueous phase or water-soluble initiators in amounts of 0.05 to 20 g/l of aqueous phase to the copolymerization system 20 minutes to 120 minutes after reaching the gel point. 2. By treatment of the strongly acidic cation exchangers with aqueous solutions of surface-active substances having a content of 0.1 to 5 g/l in the batch or column process. 3. By washing the strongly acidic cation exchangers for 1 to 4 hours with hot water at at least 60° C., subsequently separating off the water and drying the end product with utilization of the intrinsic heat.
摘要:
Sulfonated strongly acidic cation exchangers are rendered free-flowing by treatment with wetting agents or water soluble initiators, washing with water at temperatures of at least 60° C. and heat drying.