US 4,018,565 A · Automatic process titration system

Abstract

An automatic titration system and method in which the titrant is generated electrolytically and a two-position slider type ceramic sample valve, reliably, accurately and repetitively obtains a volumetric sample from a process loop and introduces it to a titration cell containing a generator or working compartment and an auxiliary compartment separated by a porous frit. The system also includes a two-position slider type ceramic reagent valve for introducing reagent into the titration cell. Titrant created at a generator electrode surface is dispersed into the bulk of the solution by a magnetically coupled impeller in the working compartment which mixes and also pumps the contents of the cell through the reagent and sample valves in a closed loop. Generator and auxiliary electrodes are connected to a current source which provides the electrolysis current. The progress of the titration is monitored by indicating and reference electrodes in the titration cell connected to an appropriate endpoint indicator, output of which is compared to a known setpoint corresponding to the titration endpoint. The total charge delivered to the generator and auxiliary electrodes during titration is measured by a timer or integrator and read out as a trend output signal. The automatic titration system and method of this invention advantageously lends itself to microprocessor control over the titration reaction and titrator sequencing.

Claims27

Dependent claims

An automatic process titration system for measuring the concentration of a process stream comprising:

a titration cell having two compartments separated by a porous membrane,
one of the titration cell compartments being a working compartment including an electrode means for generating titrant electrolytically,
means for detecting a titration endpoint operatively associated with the working compartment,
the other of the compartments being an auxiliary compartment including an electrode coupled to the generating electrode means for enabling the electrogeneration of titrant,
positionable sample valve means for obtaining a sample of the process stream,
the sample valve means having at least two operative positions and being located in relation to the process stream so as to permit process stream flow therethrough in one position and injection of a predetermined amount of sample from the process stream into the titration cell in its other position,
positionable reagent valve means for introducing reagent for generating titrant to the titration cell,
the reagent valve means having at least two operative positions and being located in relation to the titration cell so as to permit working compartment contents flow therethrough in one position and introduction of reagent to the titration cell in its other position,
the sample valve means, reagent valve means and titration cell being interconnected to form a cell loop means for the flow of titration constituents therethrough,
current source means for providing current to the titrant generating electrodes,
fluid circulating means for circulating titration constituents,
valve operating means for positioning the sample and reagent valve means, and
state generator means operatively connected to the current source means, and to the valve operating means for actuating them in a preset sequence for achieving a titration cycle.

10 more elements

A modular automatic process titrator comprising:

a titration cell containing electrode means for generating titrant and means for detecting a titration endpoint,
a valve block enclosing a positionable sample valve means for obtaining a sample of process stream and introducing it to the titration cell and a positionable reagent valve means for introducing reagent for generating titrant to the titration cell,
manifold means connecting the valve block and titration cell for providing communication between the sample and reagent valve means and the titration cell, and
flow loop block means containing passageways connecting a process sample stream with the sample valve means and providing interconnection between the sample valve means and the reagent valve means and between the reagent valve means and a reagent source.

1 more element

A method of microprocessor control of automatic process titration in which the titrant is coulometrically generated from reagent in a titration cell comprising:

sending a signal from the microprocessor to a reagent valve driver causing it to operate a valve to flush the titration cell with fresh reagent,
sending a signal from the microprocessor to a current generator causing current to be applied to the titration cell to coulometrically titrate the fresh reagent to a predetermined endpoint,
sensing the endpoint in the titration cell,
sending a signal related to the sensed endpoint to the microprocessor,
comparing the sensed endpoint to a predetermined setpoint,
sending a signal from the microprocessor to the current generator, when the predetermined setpoint is reached, to cease current application,
sending a signal from the microprocessor to a sample valve driver causing it to operate a valve to introduce a process sample to the titration cell,
sending a signal from the microprocessor to the current generator causing current to be applied to the titration cell to coulometrically generate titrant from the reagent therein,
sensing the endpoint of the reaction between the titrant and the process sample in the titration cell,
sending a signal related to the sensed endpoint to the microprocessor,
comparing the sensed endpoint to the predetermined setpoint,
determining the coulombs of charge required to reach the setpoint,
relating the coulombs required to the concentration of the process sample, and
calculating the concentration.

11 more elements

Dependencies are inferred from the claim text.

Automatic process titration system

Life of this patent

Automatic process titration system

Life of this patent

Abstract

Claims27