# US 9,517,954 B2 · Chemical injection control method and chemical injection controller > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,517,954 B2 - Document ID: US9517954B2 - Status: Granted - Kind: B2 - Application number: 14/353,852 - Filed: 2012-10-24 - Published: 2014-09-18 - Granted: 2016-12-13 - Earliest claimed: 2011-10-28 - Assignees: Asahi Kasei Chemicals Corporation - Applicants: Asahi Kasei Chemicals Corporation - Inventors: Takahiro Konishi; Shinji Okubo; Kei Hattori; Yutaka Gojo - Web page: https://patentgrep.com/patent/US9517954B2 ## CPC - C02F 1/52: by flocculation or precipitation of suspended impurities {(C02F1/463 takes precedence)} - C02F 1/008: {Control or steering systems not provided for elsewhere in subclass C02F} - C02F 1/5209: {Regulation methods for flocculation or precipitation} - C02F 1/004: {using large scale industrial sized filters} - C02F 1/283: {using coal, charred products, or inorganic mixtures containing them} - C02F 1/44: by dialysis, osmosis or reverse osmosis {(general membrane separation processes B01D61/00, membrane modules B01D63/00, electrodialysis C02F1/4693, combination of membrane modules and bioreactors C02F3/1268)} - C02F 2209/001: Upstream control, i.e. monitoring for predictive control - C02F 2209/003: Downstream control, i.e. outlet monitoring, e.g. to check the treating agents, such as halogens or ozone, leaving the process - C02F 2209/006: comprising a software program or a logic diagram - C02F 2209/02: Temperature - C02F 2209/06: pH - C02F 2209/07: Alkalinity - C02F 2209/11: Turbidity - C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes) ## Abstract A controller performs multiple regression analysis using an optimum chemical injection rate as a target variable and using one or more water quality indices of a raw water as explanatory variables and thereby derives a calculation formula for a basic chemical injection rate corresponding to the water quality indices. Next, the controller calculates the basic chemical injection rate corresponding to the water quality indices by substituting the measured values of the water quality indices of the raw water into the calculation formula. Then, the controller corrects the basic chemical injection rate based on a measured value of the water quality index of the treated water, thereby newly calculates a chemical injection rate, and outputs the newly calculated chemical injection rate as a control factor for a chemical injection pump while supplying the newly calculated chemical injection rate to calculation of the optimum chemical injection rate. ## Claims ### Claim 1 A chemical injection control method for controlling a rate of chemical injection into raw water based on water qualities of the raw water and treated water in a water purification system, the method being implemented with a controller equipped with one or more hardware storage devices having stored thereon instructions implementing the controller processes, which when executed by the controller perform the method, comprising: a process for calculating an optimum chemical injection rate by correcting a preset chemical injection rate based on a deviation of a measured value of a water quality index of the treated water from a target value of the water quality index, the measured value of the water quality index being obtained by operating a chemical injection pump based on the preset chemical injection rate; a process for performing multiple regression analysis using the optimum chemical injection rate as a target variable and using one or more water quality indices of the raw water as explanatory variables, determining partial regression coefficients of the respective explanatory variables, and thereby deriving a calculation formula for a basic chemical injection rate corresponding to the water quality indices of the raw water; a process for calculating the basic chemical injection rate corresponding to the water quality indices of the raw water by substituting the measured values of the water quality indices of the raw water into the calculation formula; and a process for correcting the basic chemical injection rate based on a measured value of the water quality index of the treated water obtained through operation of the chemical injection pump based on the basic chemical injection rate, thereby newly calculating a chemical injection rate, and outputting the newly calculated chemical injection rate as a control factor for the chemical injection pump while supplying the newly calculated chemical injection rate for calculation of the optimum chemical injection rate. ### Claim 2 (depends on 1) A chemical injection control method, wherein: in injecting a plurality of types of chemicals into raw water based on water qualities of the raw water and treated water, when a calculated value of a basic chemical injection rate of one chemical exceeds a threshold, a chemical injection rate corresponding to the threshold is output as a control factor for a chemical injection pump for the chemical and a transition is made to a process for performing chemical injection control according to claim 1 for another chemical. ### Claim 3 (depends on 1) A chemical injection control method, wherein: in injecting a plurality of types of chemicals into raw water based on water qualities of the raw water and treated water, when a calculated value of a basic chemical injection rate of one chemical exceeds a threshold, a chemical injection rate corresponding to the threshold is output as a control factor for a chemical injection pump for the chemical and a transition is made to a process for performing chemical injection control according to claim 1 for another chemical, and wherein when the calculated value of the basic chemical injection rate of the one chemical falls to or below the threshold, a transition is made from the process of chemical injection control for the other chemical to a process of chemical injection control according to claim 1 for the one chemical. ### Claim 4 (depends on 1) The chemical injection control method according to claim 1, wherein in the process for deriving the calculation formula, a value range of each water quality index of the raw water is divided into a plurality of sub-ranges and the multiple regression analysis is performed for each of the sub-ranges to derive a calculation formula for the each sub-range. ### Claim 5 (depends on 4) The chemical injection control method according to claim 4, wherein in the process for calculating the basic chemical injection rate, the basic chemical injection rate corresponding to the water quality index of the raw water is calculated through a calculation based on the calculation formula for the value range of the water quality index to which the measured value of the water quality index of the raw water belongs. ### Claim 6 (depends on 1) The chemical injection control method according to claim 1, wherein as the water quality indices of the raw water, a plurality of water quality indices are selected from among water temperature, turbidity, UV absorbance, chromaticity, pH value, alkalinity, potassium permanganate consumption, and total organic carbon. ### Claim 7 (depends on 6) The chemical injection control method according to claim 6, wherein as the water quality index of the treated water, one or more water quality indices are selected from among water temperature, turbidity, UV absorbance, chromaticity, pH value, alkalinity, potassium permanganate consumption, and total organic carbon. ### Claim 8 A chemical injection controller which controls a rate of chemical injection into raw water based on water qualities of the raw water and treated water in a water purification system, the controller including one or more hardware storage devices having stored thereon executable instructions implementing the controller processing means, the means comprising: optimum chemical injection rate calculation means for calculating an optimum chemical injection rate by correcting a preset chemical injection rate based on a deviation of a measured value of a water quality index of the treated water from a target value of the water quality index, the measured value of the water quality index being obtained by operating a chemical injection pump based on the preset chemical injection rate; multiple regression analysis calculation means for performing multiple regression analysis using the optimum chemical injection rate as a target variable and using one or more water quality indices of the raw water as explanatory variables, determining partial regression coefficients of the respective explanatory variables, and thereby deriving a calculation formula for a basic chemical injection rate corresponding to the water quality indices of the raw water; basic chemical injection rate calculation means for calculating the basic chemical injection rate corresponding to the water quality indices of the raw water by substituting the measured values of the water quality indices of the raw water into the calculation formula; and chemical injection rate calculation means for correcting the basic chemical injection rate based on a measured value of the water quality index of the treated water obtained through operation of the chemical injection pump based on the basic chemical injection rate, thereby newly calculating a chemical injection rate, and outputting the newly calculated chemical injection rate as a control factor for the chemical injection pump while supplying the newly calculated chemical injection rate to the optimum chemical injection rate calculation means.