METHOD FOR CONTROL AND ADJUSTMENT OF WATER-CHEMICAL MODE OF STEAM BOILER Russian patent published in 2020 - IPC G01N27/02 G01N33/18 

FIELD: measurement.

SUBSTANCE: invention can be used for monitoring and control of water-and-chemical conditions of low- and medium-pressure steam boilers by analyzing ratio of pH value and specific electric conductivity (EC) of boiler water with allowance for hydrolysis of carbonates in boiler water. Essence of the invention consists in that the method includes measurement in boiler water EC, pH and temperature values, wherein values of optimum EC of boiler water, at which required steam quality is provided, is determined at the stage of commissioning works, then in steady-state mode of steam boiler operation pH and EC of boiler water are measured, further calculating the boiler water pH value with the EC set based on the alkalinity values of the boiler water by methyl orange and phenolphthalein, wherein calculation of the boiler water pH value is carried out in accordance with the developed algorithm for calculating the pH value of the sodium carbonate solution with different values of alkalinity by phenolphthalein and methyl orange, wherein the measured pH value will match the calculated temperature of the boiler water sample, then all measured pH values are brought to a given temperature, then the phenolphthalein value is set less than the initially set working value by 3.0 mmol/l, and then with step of 1 mmol/l is brought to a phenolphthalein value greater than the working value by 3 mmol/l, and setting a methyl orange corresponding to each phenolphthalein value with step of 0.1 mmol/l, further, based on the developed algorithm, calculating pH values for each pair of phenolphthalein-methyl orange values, then performing the obtained data approximation and plotting the curve E=f(pH) of the water EC dependence on pH, for this purpose, for each pH value calculation of the EC value is carried out by the solution of the system of equations characterizing EC of boiler water as the sum of separate salts and bases included in its composition, taking into account boiling water evaporation and removal of carbon dioxide with steam from it, further providing constant level of EC value or boiler water pH value by controlling continuous and periodic blowing of steam boiler, then providing continuous monitoring of pH and EC of boiler water with constant comparison of obtained current values of pH and EC of boiler water with values determined by function E=f(pH), if current value of boiler water pH, at corresponding current EC value, will be less by more than 0.05 units pH than the pH value determined from the function E=f(pH) at the same current EC value, then it is diagnosed that stiffness salts enter the boiler and water treatment system operation and quality of return condensate is required.

EFFECT: higher degree of automation of operation of steam boiler, absence of constant laboratory control and related costs.

6 cl, 2 tbl, 4 dwg