Abstract: A method for preparing an electronic grade sulfuric acid from a waste sulfuric acid solution includes the steps of: performing, in sequence, a concentration treatment, a cracking treatment, and a purification treatment; performing a first oxidation treatment on sulfur dioxide; performing a first absorption treatment and a second oxidization treatment; performing an evaporation treatment; performing a first removal treatment on an acid mist containing metal ions and anion impurities; performing a second absorption treatment; and performing a second removal treatment on residual sulfur dioxide.

Abstract: An automated method of pipeline sensor integration for product mapping of a pipeline network is provided. The method includes acquiring, by a plurality of sensors of the pipeline network, first sensor responses of a pipeline in the pipeline network when a first hydrocarbon product is flowing through the pipeline. The method further includes using a prediction circuit to receive the acquired first sensor responses, integrate the received first sensor responses into one or more integrated first sensor responses in order to improve accuracy of the received first sensor responses, and identify the first hydrocarbon product in the pipeline based on the integrated first sensor responses. The prediction circuit is built from training data using a machine learning process. The training data includes first training sensor responses of the pipeline by the plurality of sensors acquired at a previous time when the first hydrocarbon product was flowing through the pipeline.

Abstract: In one embodiment, a pipeline interchange is described where a first product flows through a first pipeline and a second product flows through a second pipeline. A pipeline interchange is connected downstream to both the first pipeline and the second pipeline, wherein the pipeline interchange blends the first product flowing through the first pipeline with the second product flowing through the second pipeline. A third pipeline is connected downstream to the pipeline interchange, wherein the third pipeline flows a blended product created from the blending of the first product and the second product in the pipeline interchange. An automated analyzer can be situated downstream of the pipeline interchange capable of physical and/or chemically analyzing the blended product and generating blended data.

Abstract: In one embodiment, a process is taught where the process begins by flowing a first product through a first pipeline and flowing a second product through a second pipeline. The process then produces a blended product by mixing both the first product and the second product within a pipeline interchange which is connected downstream to both the first pipeline and the second pipeline. The blended product then flows from the pipeline interchange to a third pipeline that is connected downstream of pipeline interchange. The blended product is analyzed in the third pipeline with an automated analyzer that is capable of physical and/or chemically analyzing the blended product in the third pipeline and generating blended data.

Abstract: A technique to prevent a retrieving process of a conversion rule from taking a longer time is provided.

Abstract: An isolation device and method are provided for isolating a plumbing system of a premises from a potable water source if permissible input water pressure parameters are violated. After the plumbing system has achieved a desired input water pressure, the isolation device places the plumbing system in an isolated state and only removes the plumbing system from the isolated state if the isolation device detects a demand for water from the plumbing system and if the isolation device determines that permissible input water pressure parameters are not being violated. Once the demand no longer exists, the isolation device returns the plumbing system to the isolated state.

Abstract: A method and apparatus use conductivity to control the dosing of various chemical additives used in the water treatment industry by modulating the chemical additives within threshold setpoints. Conductivity directly correlates to concentration of chemical additives. This correlation is used to modulate the dosing rates of chemical additives into a process water stream to consistently regulate and balance chemical additive concentration within the process water stream. For example, the method and apparatus dose chlorine dioxide precursor solutions into a process water stream to generate a consistent concentration of aqueous chlorine dioxide.

Abstract: The present utility model relates to a device for improving gas detection in a photoionization detector. A gas detector is provided. The device reduces interference of photoelectric noise on the reading of the gas detector for target gases such as volatile organic compounds.

Abstract: A thermal control unit for delivering temperature-controlled fluid to one or more patient pads that are in contact with a patient is disclosed. The thermal control unit includes a fluid circuit with an inlet and outlet, a heat exchanger, a pump, and a controller. A fluid quality monitor is included in some embodiments to monitor a cleanliness of the circulating fluid and issue an alert if the cleanliness falls below a threshold. A valve may be included that is controlled by the controller based upon a measurement of the cleanliness of the circulating fluid and/or the passage of a predetermined amount of time. A second valve may also be included in some embodiments that selectively diverts fluid to an additional filter. The additional filter is used to determine if a cleaning action taken with respect to the circulating fluid was effective or not.

Abstract: The present invention relates to relates to a method of optimizing a plastic composition formed from a plurality of resin feedstocks. A plurality of resin feedstocks are provided. The plurality of resin feedstocks are blended to form the plastic composition. One or more properties of the plastic composition, including radiation absorption, radiation transmission, gas evolution, radiation fluorescence, or melting properties, are measured. The ratio of the plurality of resin feedstocks being blended into the plastic composition is adjusted, based on said measuring, to form an optimized plastic composition. A system for performing the method is also disclosed.

Abstract: Described herein is an apparatus and methods for characterizing a fluid composition including exposing electrolyte to one fluid mixture, collecting a signal from an electrode in contact with the electrolyte, and simultaneously exposing the electrolyte to a second fluid, collecting a signal from a second electrode in contact with the electrolyte exposed to the second fluid, and comparing the signal difference between the electrodes with the Nerst equation wherein the temperature of the electrolyte is above 488° C. Carbon dioxide, nitrogen, and/or oxygen may be present in the fluid and/or the second fluid.

Abstract: The device for adjusting the concentration of a gas in a liquid includes a cartridge in which the concentration of the gas in the liquid is adjusted, a pipe for supplying the liquid into the cartridge, a pipe for supplying gas into the cartridge, and a pipe for discharging the liquid from the cartridge. The gas supply pipe includes an expansion valve with of which the pressure setpoint that is controlled by a setpoint for the quantity amount of gas in the liquid and by an amount of a quantity of gas in the liquid measured by a gas concentration sensor located in the liquid discharge pipe.

Abstract: The current document discloses a ground-detecting direct-wire descaler that detects and indicates whether or not a descaling signal with sufficient current and voltage is produced or, in other words, detects and indicates whether the pipe or other equipment to which the ground-detecting direct-wire descaler is coupled is isolated from AC ground. AC-ground detection occurs both on initial power on and at regular monitoring intervals. In certain implementations, ground-detecting direct-wire descaler additionally detects and indicates whether or not the three-pronged outlet, into which the power-cord plug of the ground-detecting direct-wire descaler is inserted, conforms to UBC standards and therefore has safety ground available for use as signal ground. The ground-detecting direct-wire descaler only attempts to produce a descaling signal when safety ground is detected.

Abstract: A semiconductor manufacturing apparatus according to an embodiment comprises a container contains a mixed solution that includes a processing solution for plating processing of a substrate and an additive and being capable of draining a part of the mixed solution when a first condition is satisfied. A first supplier supplies the processing solution to the container. A second supplier supplies the additive to the container when the first condition is satisfied and drainage of a part of the mixed solution is finished.

Abstract: An injection molding system includes a sensor that detects a state of a purged molding material, and a purged material analysis unit that obtains a detection signal of the sensor and analyzes the purged molding material. Whether or not the purge operation is completed is determined based on the detection signal of the sensor so as to complete the purge operation. The purge operation is thus allowed to be completed with a minimum purge amount.

Abstract: A water monitoring device monitors and maintains swimming pool chemistry. The device mixes reagents with water in flowcells. The water chemistry is detected by measuring the light transmitted through the flowcells. The water monitoring device can communicate with computers, servers and mobile computing devices which can store and display the water chemistry information. The reagents can be stored in a replaceable reagent cartridge which can provide reagents for water testing and can be replaced when the reagents need to be replenished.

Abstract: A fluid metering system for accurately measuring and dosing one or more fluids. The fluid metering system generally includes a closed loop feedback system that monitors the volume of liquid chemical input into a system over a period of time. Based on the measured amount of chemical input into a system over a period of time, the system calculates whether or not an adjustment is required for the next input of chemical. The various embodiments utilize a measuring tube that is filled with a liquid chemical. A pressure sensor measures the pressure of the chemical in the measuring tube when filled and after emptied to calculate the total volume of chemical input into the system.

Abstract: An iterative method for controlling a production process and a production control unit for iteratively controlling the production process of at least one of a material and a product formed out of the compound material. Nominal parameters and indicative parameters selected from the group comprising process parameters, material recipe parameters and product property parameters are provided in the iterative method or to the production control unit. The iterative method and production control unit consider the nominal and indicative parameters, including both process parameters and material recipe parameters to determine whether a setting of at least one correcting parameter for a subsequent process is necessary. A correcting parameter is selected from the group comprising process parameters and recipe parameters and the setting of at least one correction parameter comprises the choice of a parameter from a parameter set comprising process parameters and material recipe parameters.

Abstract: Systems and method for detecting a concentration of a gas in a gas stream are disclosed. A method includes receiving a gas stream including a carrier gas and a processing gas. Bridge voltages of a mass flow sensor are used to produce a processing-gas concentration signal and a gas-stream mass flow rate signal. The gas stream is controlled so a mass flow rate of the processing gas equals a processing-gas-setpoint signal. In some variations, the processing-gas-concentration signal is produced using an upstream temperature of the gas stream and a bridge-derived temperature. In other variations, the processing-gas-concentration signal is produced using a top voltage of the mass flow sensor and the gas-stream mass flow rate signal.

Abstract: A method of providing a concentrate of a dissolved substance for producing a dialysis solution includes providing a container containing a solid to be dissolved, supplying water into the container for dissolving the solid, draining the concentrate of the dissolved substance from the container and topping up with water, measuring the concentration of the dissolved substance or of a parameter correlated with the concentration, and temporary or permanent suppression of the topping up of water into the container. The suppression is effected when the measured concentration value of the dissolved substance falls below a first limit value or the value of the parameter falls below or exceeds a first limit value or when the change in the concentration value of the dissolved substance or of the value of the parameter exceeds a first limit value.

Abstract: A device for measuring the absolute value of the refractive index of a liquid by immersion uses the optical properties of a cylindrical waveguide with a solid core and normal angle of incidence of the light source. The device consists of a transparent tube forming the enclosure of the waveguide, impervious to the surrounding liquid and partially filled with a transparent solid or liquid material of appropriate index of refraction, a fiber optic means of inputting light via a LED or laser and fiber optic means of coupling emerging light to a photodetector. The emerging light intensity is a function of the index of refraction of the surrounding liquid.

Abstract: A fluid metering system for accurately and consistently mixing two or more fluids together. The fluid metering system generally includes a closed loop feedback system that monitors the flow rate of the water and the volume of liquid chemical added to the water over a period of time. Based on the measured amount of chemical added to the water over a period of time, the system calculates whether or not an adjustment is required for the next addition of chemical to the water. The present invention utilizes a measuring tube that is filled with a chemical wherein a pressure sensor measures the pressure of the chemical in the measuring tube when filled and after being emptied to calculate the total volume of chemical added to the water.

Abstract: An apparatus for controlling chemical properties of a body of water, the apparatus comprising: a housing, said housing comprising: a water sample collecting subassembly; chemical reagent dispensing subassembly; a water diagnostic subassembly; and a control module, said control module disposed on the housing, said control module comprising: a means for inputting desired functional parameters and water chemical properties into the apparatus; a means for measuring the actual physical conditions of the water; a means for comparing the actual physical conditions of the water to the desired physical conditions of the water; and a means for instructing the system to dispense chemical reagents to the water at a rate and dosage necessary to cause the water to generally achieve the desired physical conditions within a desired period of time and for a desired time period; and a means for displaying the apparatus parameters and water chemical properties in human readable form.

Abstract: A chemical regulation system according to various embodiments of the present technology is configured to regulate the flow rate of a liquid and monitors the chemical composition of the liquid. The chemical regulation system may comprise various valves, fittings, and couplings configured to regulate the flow of the liquid through a production tank and into a chemical hopper to product a highly concentrated liquid/chemical solution that is provided to the production tank. The chemical regulation system may comprise a controller to electrically control various valves. The chemical regulation system may comprise a device for facilitating the flow of a liquid out of a production tank.

Abstract: Described herein is an apparatus and methods for characterizing a fluid composition including exposing electrolyte to one fluid mixture, collecting a signal from an electrode in contact with the electrolyte, and simultaneously exposing the electrolyte to a second fluid, collecting a signal from a second electrode in contact with the electrolyte exposed to the second fluid, and comparing the signal difference between the electrodes with the Nerst equation wherein the temperature of the electrolyte is above 488° C. Carbon dioxide, nitrogen, and/or oxygen may be present in the fluid and/or the second fluid.

Abstract: In a conveyor system, a conveyor having a conveyor surface transports items. An optional lubricant dispensing device dispenses a lubricant composition on the conveyor surface. A friction coefficient measuring device measures a quantity proportional to the friction coefficient of the conveyor surface and provides a signal indicative for the measured quantity proportional to the friction coefficient. A control receives the signal indicative for the measured quantity. In one embodiment, the control provides a further signal when the measured quantity exceeds a threshold value or for regulating the lubricant amount to be dispensed based on the measured quantity in order to maintain the measured quantity proportional to the friction coefficient within a predetermined range.

Abstract: A system can be constructed and operated with at least a wellbore that is connected to a gas detection system. The gas detection system can house a control module, infrared sensor, and first and second pumps in a portable case. The first and second pumps may be respectively positioned on opposite sides of the infrared sensor and configured to provide uniform sample gas flow through the infrared sensor to detect multiple different types of gasses flowing from the wellbore.

Abstract: A cooling system according to an exemplary embodiment may include a heat generation device that is cooled by a coolant solution that exchanges heat with the heat generation device to maintain the heat generation device at a required temperature. More specifically, the cooling system includes a temperature sensor that detects a temperature of the coolant solution, a conductivity sensor that detects the conductivity of the coolant solution, and a controller that uses coolant solution temperature and coolant solution conductivity that are detected through the temperature sensor and the conductivity sensor to determine a condition of the coolant solution.

Abstract: A method comprises transporting a first stream of a carrier gas to a delivery device that contains a solid precursor compound. The first stream of carrier gas is at a temperature greater than or equal to 20° C. The method further comprises transporting a second stream of the carrier gas to a point downstream of the delivery device. The first stream and the second stream are combined to form a third stream, such that the dewpoint of the vapor of the solid precursor compound in the third stream is lower than the ambient temperature. The flow direction of the first stream, the flow direction of the second stream and the flow direction of the third stream are unidirectional and are not opposed to each other.

Abstract: A method and system for supplying additional hydrogen from a reservoir of stored hydrogen in a salt cavern to a hydrogen pipeline to assist in meeting customer demand for hydrogen is provided. Contaminants introduced while the stored hydrogen stream is in the salt cavern may cause the crude hydrogen stream to not have the required product purity specification. The stored hydrogen is removed from the salt cavern as a crude hydrogen stream and thereafter diluted with higher purity hydrogen formed from the pipeline to form a hydrogen product stream at or below the product purity specification. The hydrogen product can be formed without removal of any of the contaminants in the crude stream, thereby creating a more cost effective and simplified supply process compared to conventional processes employing a salt cavern for hydrogen supply.

Abstract: An object of this invention is to provide a responsive material gas concentration control system that can be mounted on a bubbling system and that can control a concentration of a material gas in a mixed gas at a constant value even though a partial pressure of the material gas fluctuates. The material gas concentration control system is used for a material evaporation system, and comprises a body that is connected to an outlet line and that has an internal flow channel for flowing the mixed gas, a concentration measuring part that measures the concentration of the material gas in the mixed gas, and a first valve that is arranged downstream of the concentration measuring part and that adjusts the measured concentration measured by the concentration measuring part at a previously determined set concentration, wherein the concentration measuring part and the first valve are mounted on the body.

Abstract: A method comprises transporting a first stream of a carrier gas to a delivery device that contains a solid precursor compound. The first stream of carrier gas is at a temperature greater than or equal to 20° C. The method further comprises transporting a second stream of the carrier gas to a point downstream of the delivery device. The first stream and the second stream are combined to form a third stream, such that the dewpoint of the vapor of the solid precursor compound in the third stream is lower than the ambient temperature. The flow direction of the first stream, the flow direction of the second stream and the flow direction of the third stream are unidirectional and are not opposed to each other.

Abstract: A gas concentration control device for pressure vessel is provided for controlling gas concentration inside an accommodation space that is set in an interior of a chamber formed inside a pressure vessel curing oven. The pressure vessel curing oven includes a gas inlet tube with a first valve and a gas outlet tube with a second valve, which are in communication with the accommodation space. The gas concentration control device includes a gas concentration detection device, which is operative for timed detection of concentration of a gas inside the accommodation space, and a control unit for setting a predetermined concentration, performing a judgment if the gas concentration inside the accommodation space reaches the predetermined concentration according to a detection result of the gas concentration detection device, and thereby controls the first valve and the second valve according to result of the judgment.

Abstract: A method of determining an operational parameter of a washing system having a wash tank to which water and material are added. In some embodiments, the method includes establishing a communication link between a sensor and a controller. The sensor is positioned in the wash tank and transmits a signal indicative of a material concentration. The controller receives the signal. Additionally, the method includes adding material to water in the wash tank, monitoring the material concentration while material is being added, and stopping the material addition upon the material concentration reaching a predetermined material concentration. The controller then determines an operational parameter indicative of the amount of material that is needed to reach the predetermined material concentration.

Abstract: Scaling is controlled in a cooling water system with CO2 based upon measurements of the cooling water's pH, alkalinity and Ca2+concentration.

Abstract: A probe for measuring oxygen, temperature, and pressure in a space to be monitored, comprising: a housing, comprising a thermally conductive material; an oxygen sensor disposed within the housing, comprising: a first end having coated thereon a coating which fluoresces at a fluorescent frequency when exposed to light having an excitation frequency in the absence of associated oxygen, and which undergoes a dampening of said fluorescence in the presence of associated oxygen; and a second end operatively connected to an optical fiber that extends through the housing; wherein the first end extends through the housing and is adapted to be exposed to the space to be monitored; a temperature sensor disposed within the housing adjacent to the thermally conductive material, comprising a fiber Bragg grating, or a semiconductor material, such as a GaAS material, wherein the temperature sensor does not extend through the housing and is not exposed to the space to be monitored; a pressure sensor disposed within the housin

Abstract: To prevent loss of control of a pressure of a source gas within a movable range of a control valve, a source gas concentration control system is provided. The system may include a first valve that is provided on an outlet line, a concentration measurement part that measures a concentration of the source gas in mixed gas, and a concentration control part that controls a stroke of the first valve such that the measured concentration of the source gas becomes equal to a predetermined concentration setting. The measured concentration may be measured in the concentration measurement part. The system may further include a temperature controller that controls a temperature inside the tank to meet a temperature setting, and a temperature setting part that sets the temperature setting of the temperature controller.

Abstract: A material gas concentration control system for keeping a concentration of a material gas in a mixed gas constant comprising a tank to accommodate the material, an inlet line to input a carrier gas for evaporating the accommodated material into the tank, and an outlet line to output the mixed gas consisting of the material gas evaporated in the tank and the carrier gas, and further comprising a first valve arranged in the inlet line, a concentration measuring part that measures the concentration of the material gas in the mixed gas, and a concentration control part that controls an open degree of the first valve so as to make the measured concentration of the material gas measured by the concentration measuring part become the previously determined set concentration.

Abstract: A method comprises transporting a first stream of a carrier gas to a delivery device that contains a solid precursor compound. The first stream of carrier gas is at a temperature greater than or equal to 20° C. The method further comprises transporting a second stream of the carrier gas to a point downstream of the delivery device. The first stream and the second stream are combined to form a third stream, such that the dewpoint of the vapor of the solid precursor compound in the third stream is lower than the ambient temperature. The flow direction of the first stream, the flow direction of the second stream and the flow direction of the third stream are unidirectional and are not opposed to each other.

Abstract: A method and system for providing nitrogen-enriched air (NEA) to aircraft fuel tanks using multiple air separation modules (ASMs). The ASMs employ membranes having different permeabilities and selectivities which are particularly selected to meet the varying NEA needs of the fuel tanks during flight.

Abstract: A method for tracking a pollution source in process water is presented. Firstly, variation curves of drain water drained from different rinsing tanks are respectively obtained, and a water quality concentration of the drain water drained to a buffer tank is detected, so as to output a water quality variation curve. Then, an analytical comparison is performed on each drain water amount variation curve and the water quality variation curve within a same time interval, so as to output an analytical result of each flow of drain water in a range exceeding a predetermined water quality standard. In this manner, the drain water that exceeds the predetermined water quality standard can be tracked in real-time according to the analytical result, thereby quickly improving the process for discharging the drain water.

Abstract: A system for providing constant flow on-line dilution comprising a first fluid introduction line carrying a first fluid, a second fluid introduction line carrying a second fluid, a flow path selection assembly coupled to the fluid introduction line and the second fluid introduction line, a mixing assembly suitable for mixing the first fluid, the second fluid and a sample, and a plurality of fluid transport lines coupled to the flow path selection assembly suitable for transporting the first fluid, the second fluid and a sample to the mixing assembly. The flow path selection assembly is suitable for selecting a flow path for each of the first fluid introduction line and second fluid introduction lines and providing changeable coupling of each of the first fluid introduction line and second fluid introduction line to one of the plurality of fluid transport lines through the flow path selection assembly.

Abstract: A method for tracking a pollution source in process water is presented. Firstly, variation curves of drain water drained from different rinsing tanks are respectively obtained, and a water quality concentration of the drain water drained to a buffer tank is detected, so as to output a water quality variation curve. Then, an analytical comparison is performed on each drain water amount variation curve and the water quality variation curve within a same time interval, so as to output an analytical result of each flow of drain water in a range exceeding a predetermined water quality standard. In this manner, the drain water that exceeds the predetermined water quality standard can be tracked in real-time according to the analytical result, thereby quickly improving the process for discharging the drain water.

Abstract: A method and system of controlling addition of a treating agent based on a control function comprising a plurality of demand values is disclosed. Process parameters of a fluid to be treated are measured and one or more control signals are generated based on the measured process values and the control function. The control signals are used to actuate a treating agent dosing system and also used to monitor and compare the levels, status or condition of the treating agent. Additional features of the invention compensate for rain events.

Abstract: An automated solution maker is provided. The automated solution maker mixes a chemical with a solvent to a desired concentration. The concentration of the solution is monitored by measuring the conductivity of the solution. Based upon this measurement, the concentration of the solution may be adjusted.

Abstract: Method for supplying a high purity gas product comprising providing a first gas stream including a major component and at least one impurity component, determining the concentration of the at least one impurity component, and comparing the concentration so determined with a reference concentration for that component. When the value of the concentration so determined is less than or equal to the reference concentration, the first gas stream is utilized to provide the high purity gas product. When the value of the concentration so determined is greater than the reference concentration, a second gas stream comprising the major component is provided and the first and second gas streams are mixed to yield a mixed gas stream having a concentration of the at least one impurity component that is less than the reference concentration.

Abstract: A system (10) for delivery of dilute fluid, utilizing an active fluid source (12), a diluent fluid source (14), a fluid flow metering device (24) for dispensing of one of the active and diluent fluids, a mixer (28) arranged to mix the active and diluent fluids to form a diluted active fluid mixture, and a monitor (42) arranged to sense concentration of active fluid and/or diluent fluid in the diluted active fluid mixture, and responsively adjust the fluid flow metering device (24) to achieve a predetermined concentration of active fluid in the diluted active fluid mixture. A pressure controller (38) is arranged to control flow of the other of the active and diluent fluids so as to maintain a predetermined pressure of the diluted active fluid mixture dispensed from the system. The fluid dispensed from the system then can be adjustably controlled by a flow rate controller, e.g., a mass flow controller, to provide a desired flow to a fluid-utilizing unit, such as a semiconductor process tool.

Abstract: An object of this invention is to provide a responsive material gas concentration control system that can be mounted on a bubbling system and that can control a concentration of a material gas in a mixed gas at a constant value even though a partial pressure of the material gas fluctuates. The material gas concentration control system is used for a material evaporation system, and comprises a body that is connected to an outlet line and that has an internal flow channel for flowing the mixed gas, a concentration measuring part that measures the concentration of the material gas in the mixed gas, and a first valve that is arranged downstream of the concentration measuring part and that adjusts the measured concentration measured by the concentration measuring part at a previously determined set concentration, wherein the concentration measuring part and the first valve are mounted on the body.

Abstract: A material gas concentration control system for keeping a concentration of a material gas in a mixed gas constant comprising a tank to accommodate the material, an inlet line to input a carrier gas for evaporating the accommodated material into the tank, and an outlet line to output the mixed gas consisting of the material gas evaporated in the tank and the carrier gas, and further comprising a first valve arranged in the inlet line, a concentration measuring part that measures the concentration of the material gas in the mixed gas, and a concentration control part that controls an open degree of the first valve so as to make the measured concentration of the material gas measured by the concentration measuring part become the previously determined set concentration.

Abstract: The recycling apparatus of waste sulfuric acid for collecting waste sulfuric acid generated at a source site A, transporting it by a carrier B, and recycling it for reuse at a user site C, the recycling apparatus of waste sulfuric acid including a receiving tank for receiving virgin sulfuric acid (a) and waste sulfuric acid (b) having a concentration different from that of the virgin sulfuric acid, and including (1) a mixer alone, (2) a mixer and a concentration monitor, or a mixer and a cooler in combination, or (3) a mixer, a concentration monitor, and a cooler in combination.