Pure chlorine dioxide generation system with reduced acid usage

Abstract

A method of generating chlorine dioxide is disclosed. The method may include feeding a reaction mixture into a separator. The reaction mixture may follow a spiral path through the separator and generate gaseous chlorine dioxide within the separator. The gaseous chlorine dioxide may be extracted from the separator and used to disinfect process water.

Description

background 1. Technical Field

[0002] The present disclosure generally relates to methods of generating chlorine dioxide and methods of treating process water by on-site generation of chlorine dioxide. 2. Background technology

[0004] As the use of gaseous chlorine as a microbicide decreases, various alternatives have been explored; including bleach, bromide-containing bleach, bromochlorodimethylhydantoin, ozone, and chlorine dioxide (ClO2). Among them, chlorine dioxide has attracted a lot of attention in controlling microbial growth in many different industries, including the dairy industry, beverage industry, pulp and paper industry, fruit and vegetable processing industry, various canning plants, poultry industry, beef processing industry, and various other food processing applications. Because chlorine dioxide is selective for specific environmentally hazardous wastes, its use in municipal drinking water treatment facilities and industrial waste treatment facilities has also increased, and the specific environmentally hazardous wastes include phenols, sulfides, cyanides, thiosulfates, and mercaptans. In addition, chlorine dioxide is used in downhole applications in the oil and gas industry as a well stimulation additive.

[0005] Unlike chlorine, chlorine dioxide remains a gas when dissolved in an aqueous solution and does not ionize to form a weak acid. This property is at least partially responsible for the biocidal effectiveness of chlorine dioxide over a wide pH range. In addition, chlorine dioxide is a very effective microbicide over a wide pH range at concentrations as low as 0.1 parts per million (ppm).

[0006] It is believed that the biocidal activity of chlorine dioxide is due to its ability to penetrate bacterial cell walls and react with essential amino acids within the cytoplasm to disrupt cellular metabolism. This mechanism is more effective than other oxidants that "burn" on contact and is very effective against Legionella, algae and amoeba cysts, Giardia cysts, E. coli, salmonella, shigella, and cryptosporidium.

[0007] Unfortunately, chlorine dioxide is unstable in solution, has a very short shelf life, and is therefore commercially available only as a liquid product at less than 3000 ppm. For applications requiring large amounts of chlorine dioxide, chlorine dioxide must typically be generated at the time of its use, for example, by the reaction between an aqueous solution of a metal chlorate or metal chlorite and a liquid-phase strong acid. However, the use of a liquid-phase strong acid creates handling and safety issues. Summary of the invention

[0008] A method for generating chlorine dioxide is disclosed. The method may include feeding a reaction mixture into a separator; directing the reaction mixture through the separator in a spiral path; generating gaseous chlorine dioxide in the separator; and extracting the gaseous chlorine dioxide from the separator.

[0009] In some aspects, the method can include feeding a first solution comprising an acid into a mixing device through a first feed line; feeding a second solution comprising a chlorite or a chlorate into the mixing device through a second feed line; and mixing the first solution and the second solution in the mixing device to form a reaction mixture. The mixing device can be in fluid communication with a separator.

[0010] A method for treating process water is provided. The method may include feeding a first solution comprising an acid into a mixing device through a first feed line; feeding a second solution comprising a chlorite or a chlorate into the mixing device through a second feed line; mixing the first solution and the second solution in the mixing device to form a reaction mixture, wherein the mixing device is in fluid communication with a separator; generating chlorine dioxide in the separator; extracting chlorine dioxide from the separator; and injecting chlorine dioxide into the process water.

[0011] In some aspects, the method can include reacting an acid with a chlorite or chlorate to produce chlorine dioxide in a separator.

[0012] In some aspects, the acid is hydrochloric acid, phosphoric acid, sulfuric acid, hypochlorous acid, or any combination thereof.

[0013] In some aspects, the acid comprises sulfuric acid and the second solution comprises chlorate and hydrogen peroxide.

[0014] In some aspects, the acid comprises hydrochloric acid and the second solution comprises chlorite.

[0015] In some aspects, the helical path is defined by a tube having a coiled configuration with a coil plane angle of about 1 degree to about 60 degrees.

[0016] In some aspects, the first feed line and the second feed line are opposite each other and point toward each other.

[0017] In some aspects, the separator can operate at a pressure approximately equal to or less than atmospheric pressure.

[0018] In some aspects, the residence time of the reaction mixture in the separator can be from about 0.1 minutes to about 1 hour.

[0019] In some aspects, the method can include generating chlorine dioxide at a rate in a range of about 0.001 lbs / hour to about 200 lbs / hour.

[0020] In some aspects, the method can include operating the separator at a temperature in a range of about 2°C to about 80°C.

[0021] In some aspects, the reaction mixture can be fed into the top portion of the separator.

[0022] In some aspects, the reaction mixture can be fed into the bottom portion of the separator.

[0023] In some aspects, the reaction mixture can be fed into a middle portion of the separator.

[0024] In some aspects, the method can include withdrawing liquid from the separator and recycling the liquid to the separator.

[0025] In some aspects, the spiral path can be defined by a plurality of plates disposed within the separator.

[0026] In some aspects, the plurality of plates includes a plate having perforations.

[0027] In some aspects, the average conversion efficiency of the reaction can be at least about 90%.

[0028] A method of treating process water is provided. The method may include generating chlorine dioxide as described herein and injecting gaseous chlorine dioxide into the process water.

[0029] The above has been a fairly broad overview of the features and technical advantages of the present disclosure so that the following specific description may be better understood. The following will describe additional features and advantages of the present disclosure that form the subject matter of the claims of this application. It will be appreciated by those skilled in the art that the disclosed concepts and specific embodiments may be easily utilized as a basis for modifying or designing other embodiments in order to perform the same purpose of the present disclosure. It will also be appreciated by those skilled in the art that such equivalent embodiments do not depart from the spirit and scope of the present disclosure as set forth in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The detailed description of the present invention is described below with specific reference to the accompanying drawings, in which:

[0031] Figure 1 An embodiment of a system for generating chlorine dioxide is shown;

[0032] Figure 2 An embodiment of a chlorine dioxide generating system is shown in which three reactants are mixed and fed into a separator;

[0033] Figure 3 An embodiment of a chlorine dioxide generating system having a control valve is shown;

[0034] Figure 4 An embodiment of a separator is shown;

[0035] Figure 5A An embodiment of a conical separator is shown;

[0036] Figure 5B A cross-sectional top view of a conical separator is shown;

[0037] Figure 6 An embodiment of a separator is shown;

[0038] Figure 7 An embodiment of a separator is shown;

[0039] Figure 8 The relationship between power water temperature and average conversion efficiency is shown;

[0040] Fig. 9 The relationship between the molar ratio of sulfuric acid to chlorate and the chlorate conversion is shown;

[0041] Fig.10 An embodiment of a mixer and reactant feed lines is shown; and

[0042] Fig.11 An embodiment of a coil disposed within a separator is shown. DETAILED DESCRIPTION

[0043] Various embodiments are described below with reference to the accompanying drawings, wherein similar elements are generally referred to by similar numbers. The relationship and function of the various elements of the embodiments can be better understood by reference to the following detailed description. However, the embodiments are not limited to those shown in the accompanying drawings. It should be understood that the drawings are not necessarily drawn to scale, and in some cases, details that are not necessary for understanding the embodiments disclosed herein, such as conventional manufacturing and assembly, may have been omitted.

[0044] With reference to the accompanying drawings, Figure 1 A reactant feed line 100 is shown in fluid communication with a separator 101. The separator 101 can be in fluid communication with a product line 102 from which a gaseous product can be extracted. The acid can be stored in a first storage container 103 in fluid communication with a first feed line 104. The chlorate or chlorite can be stored in a second storage container 105 and can be in fluid communication with a second feed line 106. The first feed line 104 and the second feed line 106 can be in fluid communication with a mixer 107. Power water can also be fed into the mixer. The first solution and the second solution are mixed in the mixer 107 and then pass through the reactant feed line 100 into the separator 101. The acid can react with the chlorite or chlorate to produce chlorine dioxide in the separator 101. As the chlorine dioxide is generated, the chlorine dioxide can be extracted from the separator 101 into the product line 102.

[0045] In some aspects, the acid is hydrochloric acid, phosphoric acid, sulfuric acid, hypochlorous acid, or any combination thereof. In some aspects, the acid comprises sulfuric acid. The second solution may comprise a mixture of chlorate and hydrogen peroxide.

[0046] In some aspects, the first solution may be composed of or include sulfuric acid and water, wherein the sulfuric acid concentration ranges from about 50% to about 98% by weight. The sulfuric acid concentration in the first solution may be about 78%. In some aspects, the second solution may include or include chlorate, hydrogen peroxide, and water. The second solution may include chlorate in a concentration range of about 25% to about 60% by weight. The concentration of chlorate in the second solution may be about 40% by weight. The concentration of hydrogen peroxide in the second solution may be in a range of about 2% to about 30% by weight. The concentration of hydrogen peroxide in the second solution may be about 8% by weight. In some aspects, the acid may be sulfuric acid, and the chlorate may be sodium chlorate.

[0047] In other aspects, the acid comprises hydrochloric acid and the second solution comprises chlorite.

[0048] The separator 101 may have a top portion 110 and a bottom portion 111. A plurality of plates 112 may be disposed within the separator 101, the plurality of plates defining a spiral path for the reactant mixture to flow. Liquid may accumulate at the bottom of the separator 101. The level of the liquid 112 in the separator may be controlled and adjusted by one of ordinary skill in the art to maximize the production of gaseous chlorine dioxide.

[0049] As used herein, "spiral path" refers to the track of the reaction mixture when it flows through the separator. The term "spiral path" may include any nonlinear path through the separator, but does not include a spiral path that meets the liquid in the mixing vessel, such as in a continuous stirred tank reactor or a batch reactor with a mechanical stirring device. The spiral path can be limited by the perforations in the plate, tube or tube or plate inside the separator. The spiral path can extend from the top of the separator to the bottom or from the bottom of the separator to the top.

[0050] Liquid products or unreacted chemicals at the bottom of separator 101 may be extracted into recycle line 122 or liquid product extraction line 113, and may be diverted into line 114 for mixing with product line 102 or into line 115 for feeding to waste disposal.

[0051] Power water can be fed into ejector 116 through power water line 118 and mixed with the product in line 102 and fed into treatment line 117 which can be in communication with process fluids. For example, treatment line 117 can deliver chlorine dioxide to cooling tower water to disinfect the water. Another power water line 119 can deliver water to ejector 120 which mixes the liquid from line 115 and feeds it into line 121 which delivers the liquid to waste disposal or for use in a different process.

[0052] In some aspects, the first solution in the first feed line 104 and the second solution in the second feed line 106 can pass through a heat exchanger 109. The heat exchanger 109 can adjust the temperature of the feed solutions to maximize conversion and minimize adverse reactions when mixing the solutions. For example, the temperature of the solutions in the first feed line and the second feed line can be adjusted to a temperature between about 2°C and about 80°C.

[0053] In some aspects, pump 123 can be connected to recirculation line 122 and feed liquid into heat exchanger 109. Pump 108 can be connected to a reactant storage vessel to feed solution into the separator.

[0054] In some aspects, the method may include measuring the temperature of the first solution and / or the second solution. The temperature may be measured before entering the heat exchanger. If a third reactant is mixed, the method may include measuring the temperature of the third reactant.

[0055] Figure 2 A system configuration is shown in which the third storage container 200 can store additional reactants, which can be pumped by the pump 108 into the third feed line 201 to be fed into the mixer 107. The third solution in the third feed line 201 can be mixed with the first solution and the second solution in the mixer 107.

[0056] In some aspects, a portion of the third solution can be diverted through line 202 and mixed with the second solution in the second feed line 106 prior to entering the heat exchanger 109 .

[0057] In some aspects, the first solution can be an acid, the second solution can be a chlorate, and the third solution can be hydrogen peroxide.

[0058] Figure 3 It is shown that pipeline valves 300 can be placed on certain pipelines to control the flow through various parts of the system. For example, valves on certain liquid product pipelines can be used to control the liquid level 112 in the separator 101. Alternatively, the liquid level 112 can be adjusted by changing the pumping rate of the pump 123 and the outlet height level of the pipeline 113.

[0059] In some aspects, the chlorine dioxide in line 102 can be combined with the reactant from line 114, the combination being controlled by valve 300. In some aspects, the chlorine dioxide in line 102 can be fed to the process water via line 117 without mixing with the liquid in line 114. The reactant in line 114 can be fed to the process via line 121 for pH control.

[0060] Figure 4 An embodiment of a separator is shown in which a reaction mixture 400 can be fed into the separator 101. The reaction mixture can follow a spiral path defined by a plate 402 disposed within the separator 101. A gaseous product 401 can be withdrawn in the product line 102 and a liquid product 403 can be withdrawn in the liquid product line 404. In some aspects, the plate can have a plurality of perforations that allow the gaseous product to pass through the outlet via the product line 102.

[0061] Figure 5A An embodiment of a separator is shown in which the separator 101 has a conical shape that helps create a spiral path 500 in the separator for the reactant mixture 400. The inner surface of the separator 101 may include fins or plates that protrude into the center of the conical separator that facilitate movement of the reactant mixture 400 in the spiral path 500. Figure 5B Shows Figure 5A Cross-sectional top view of a conical separator.

[0062] Figure 6 An embodiment of a separator is shown in which the reactant feed line 100 may be a plurality of perforations or holes 600 that allow gaseous products to exit the tube. The reaction mixture may pass through the tube 601 in a spiral path downward through the separator 101. The contents of the tube exit at the bottom of the separator 101. Liquid 403 may be removed from the separator via line 404.

[0063] In some aspects, tube 601 can include at least two, three, four, or more contact zones 602. The inner diameter of the contact zone can be at least about two times larger than the inner diameter of the tube. In some aspects, the inner diameter of the contact zone can be at least about three, four, or five times larger than the inner diameter of the reactor.

[0064] In some aspects, the length of the tube may be in the range of about 25 inches to about 300 inches. In some embodiments, the length of the reactor may be in the range of about 30 inches to about 90 inches, about 30 inches to about 80 inches, about 30 inches to about 70 inches, about 30 inches to about 60 inches, about 30 inches to about 50 inches, about 40 inches to about 90 inches, about 40 inches to about 80 inches, about 35 inches to about 45 inches, or about 35 inches to about 60 inches. In other aspects, the length of the tube may be about 40 inches.

[0065] In some aspects, the inner diameter of the tube can be in the range of about 0.1 inches to about 4 inches. In some aspects, the inner diameter of the tube can be in the range of about 1 inch to about 1.25 inches, or about 0.25 inches to about 1.25 inches. In some aspects, the inner diameter of the tube can be about 0.25 inches, about 2 inches, about 3 inches, or about 4 inches. In other aspects, the inner diameter of the tube can be about 1.25 inches, about 1 inch, about 0.75 inches, about 0.375 inches, or about 0.1875 inches.

[0066] Figure 7 An embodiment of a separator is shown. In this embodiment, the reaction mixture 400 can be fed into the bottom portion of the separator 101. In some aspects, the reaction mixture can be fed into the top portion of the separator. In some aspects, the reaction mixture can be fed into the middle portion of the separator.

[0067] Figure 7 Also shown is that gaseous product 701 can pass through perforations or holes in plates 402 disposed within separator 101. In some aspects, only the top plate at the top portion of the separator has holes or perforations to allow gas to pass through plates 402 and into product line 102.

[0068] Fig.10 100. An embodiment is shown in which the first feed line and the second feed line are opposite and directed toward each other. As the solution enters the mixer 107, the solution can be more evenly mixed and fed into the reactant feed line 100. The first feed line and the second feed line can be opposite and directed toward each other in a "T" configuration, see for example Fig.10 Reference numerals 104 and 106 correspond to the orientation of the components.

[0069] In some aspects, the spiral path is defined by a tube having a coiled configuration with a coiling plane angle of about 1 degree to about 60 degrees. In some aspects, the coiling plane angle can be about 5 degrees to about 30 degrees. The tube having a coiled configuration can include a coiling diameter. The coiling diameter can be in the range of about 0.1 to about 16.0 inches, about 1 inch to about 16 inches, about 2 inches to about 16 inches, about 2 inches to about 10 inches, or about 2 inches to about 4 inches.

[0070] Fig.11 An embodiment is shown in which the tube 601 may include a coiled configuration. The tube having a coiled configuration may include a coil plane angle 900 in the range of about 5 degrees to about 30 degrees. The tube having a coiled configuration may include a coil diameter 901. The coil diameter 901 may be in the range of about 0.1 inches to about 4.0 inches.

[0071] In some aspects, the separator can be operated at a pressure approximately equal to or less than atmospheric pressure. Atmospheric pressure can be in the range of about 33 kPa to about 107 kPa. In some aspects, the operating pressure is about 106 kPa. In some aspects, the separator is operated under vacuum.

[0072] In some aspects, the method can include extracting the chlorine dioxide using an ejector.Other means can be used to extract the chlorine dioxide from the separator and the present disclosure is not limited to the use of an ejector.

[0073] In some aspects, the method can include operating the separator at a temperature in the range of about 2° C. to about 80° C. In some aspects, the method can include operating the reactor at a temperature of about 60° C.

[0074] In some aspects, the temperature of the motive water may be in the range of about 2° C. to about 80° C. The motive water temperature may be in the range of about 15° C. to about 70° C., about 30° C. to about 70° C., about 40° C. to about 70° C., about 40° C. to about 60° C., or about 50° C. to about 70° C.

[0075] In some aspects, the residence time of the reaction mixture in the separator can be about 0.1 minute to about 1 hour. In some aspects, the residence time of the reaction mixture in the reactor can be at least about 1 minute. In other embodiments, the reaction mixture can stay in the reactor for at least about 3 minutes, at least about 4 minutes, at least about 5 minutes, at least about 6 minutes, at least about 7 minutes, at least about 8 minutes, at least about 9 minutes, or at least about 10 minutes. In some embodiments, the residence time of the reaction mixture in the reactor can be about 3.8 minutes. The residence time can be calculated by dividing the total separator liquid volume by the total reactant flow rate.

[0076] In some aspects, the method can include generating chlorine dioxide at a rate in the range of about 0.001 lbs / hour to about 200 lbs / hour. In some aspects, chlorine dioxide can be generated at a rate in the range of about 0.001 lbs / hour to about 100 lbs / hour. In some aspects, chlorine dioxide can be generated at a rate in the range of about 0.02 lbs / hour to about 15 lbs / hour. In some aspects, chlorine dioxide can be generated at a rate in the range of about 5 lbs / hour to about 15 lbs / hour.

[0077] In some aspects, the average conversion efficiency of the reaction can be at least about 90%.

[0078] In some aspects, the power water line may include at least two channels. The channel may be longitudinal. In some embodiments, the power water line may be a double sealed pipe. The power water line may have an inner channel and an outer channel through which the power water can flow, and the first solution and the second solution can be combined in the inner channel. The power water flow rate in the outer channel may be different from the flow rate in the inner channel. The power water flow rate may allow the temperature of the reaction mixture to be controlled within a certain range. The reaction mixture temperature may be about 2°C to about 80°C, about 2°C to about 70°C, about 35°C to about 70°C, about 40°C to about 70°C, or about 50°C to about 70°C. The reaction mixture temperature may be about 60°C.

[0079] A method of treating process water is provided. The method may include generating chlorine dioxide as described herein and injecting gaseous chlorine dioxide into the process water.

[0080] In some aspects, the method can include determining the chlorine dioxide demand in the process water using measurements from sensors (such as chlorine dioxide sensors), oxidation and reduction potentials, flow meters, microbiological measurements, or any combination thereof. In some aspects, chlorine dioxide can be added to the process water in a cooling tower.

[0081] In some aspects, chlorine dioxide can be added to an aqueous system such as a cooling tower. However, the present disclosure is not limited to adding chlorine dioxide to process water in a cooling tower. Process water can be used in the textile industry, laundry, papermaking, mining, or energy services.

[0082] In some embodiments, the method may include a process control system including a programmable logic controller (PLC), a chlorine dioxide analyzer, a pressure transmitter (PT), and a flow transmitter (FT) controlling feed pumps for chemicals to the reactor and for power water.

[0083] In some embodiments, the method may include a distribution system. The distribution system may include at least two independently controlled dosing points. When different ClO2 production set points are input into the controller, the PLC automatically calculates and adjusts the required production of the chlorine dioxide reactor. The distribution system allows the chlorine dioxide solution to be distributed directly from the discharge chlorine dioxide reactor to multiple points, thereby avoiding the storage tank system. The distribution system may incorporate a ClO2 solution pump and flow meter and a control valve to manage the distribution between the various dosing points.

[0084] The flow meter that can be used with the disclosed method can be any suitable flow meter, such as but not limited to a clamp-on or pulse flow meter. A pulse-based flow meter uses an optical or magnetic sensor to detect the kinetic energy of a flowing fluid and converts it into electrical energy in the form of digital pulses. The flow rate can be determined by measuring the period of the pulse.

[0085] The pumps used to feed the first solution and the second solution can communicate with the PLC. The PLC can also communicate with any pumps placed in the feed lines.

[0086] In some aspects, any of the methods disclosed herein can include sensing the pressure inside the separator. In some aspects, the product feed line can be equipped with a check valve, a flow meter, and a feed pump.

[0087] In certain embodiments, any of the methods disclosed herein may include calculating a chlorine dioxide dosage. The chlorine dioxide dosage may be calculated using the flow rates of the first solution, the second solution, the power water, the chlorine dioxide solution in the product feed line, and the chlorine dioxide concentration. For example, the chlorine dioxide concentration in the main line may be calculated using the following formula: Main line product rate = (F p +F a +F w -F 产物管线 )*C ClO2 , where F p is the flow rate of hydrogen peroxide and chlorate, F a is the acid flow rate, F w is the flow rate of power water, F 产物管线 is the sum of the flows in any product feed lines connected to the main line, and C ClO2 is the concentration of chlorine dioxide.

[0088] A number of alarm and fail-safe settings may be set using the PLC. For example, a pump problem may be detected by monitoring the difference between the flow meter reading and the calculated pump speed. Some fail-safes may include a pressure reducing valve on the separator or product feed line. Any of the feed lines may have a pressure sensor that communicates the reading to the main control. For example, the main control may include a PLC and an Adam AI / AO (analog input / analog output) module. If the reactor is housed in a cabinet, the cabinet may have a leak detection sensor and a cabinet door lock.

[0089] Example

[0090] Example 1: The effect of reactor temperature on conversion efficiency was measured. The diameter of the tube in the separator was about 1 / 4 inch, and the ClO2 production rate was about 0.085 lbs / hour. The chemicals were fed via pumps 103 and 105, mixed in device 107, and then entered separator 601. The generated ClO2 was separated from the reactants in the tube, and the reactants continued to flow down the path in the tube. Figure 8 It is shown that the conversion efficiency increases with the increase in the temperature of the chemicals in the reaction. In this reaction, the calculated residence time is about 14 minutes.

[0091] Example 2: Testing the effect of the molar ratio of acid to chlorate on conversion. Fig. 9 It is shown that as the molar ratio increases, the chlorate conversion increases for both 100 sec chlorate conversion (CVS) % and >120 sec CVS ​​%.

[0092] Example 3: Conversion was measured for a separator having a tube with approximately 3 / 8 inch spiral tubing within the separator. Table 1 shows the conversion for various liquid velocities.

[0093] Table 1. Effect of residence time and temperature on conversion.

[0094]

[0095] Example 4: In this experiment, the temperature of the reactants was maintained at about 62°C and the diameter of the tube was about 3 / 8 inch. The residence time was calculated to be about 14 minutes.

[0096] Table 2. Acid reduction performance at 62°C.

[0097]

[0098] Example 5: In this experiment, the temperature was varied to observe the effect on conversion efficiency. The diameter of the tube was about 3 / 8 inch. The residence time was calculated to be about 11.2 minutes.

[0099] Table 3. Effect of reaction temperature on average conversion efficiency.

[0100]

[0101] Any composition disclosed herein may comprise, consist of, or consist essentially of any compound / component disclosed herein. According to the present disclosure, the phrase "consist essentially of, consists essentially of, consisting essentially of" and the like limits the scope of the claim to the specified materials or steps and those materials or steps that do not substantially affect one or more basic and novel characteristics of the claimed invention.

[0102] As used herein, the term "about" means that the stated value is within the error caused by the standard deviation found in its respective testing measurements, and if such error cannot be determined, then "about" means within 10% of the stated value.

[0103] All devices and methods disclosed or claimed herein can be made and performed without undue experimentation in accordance with the present disclosure. Although the present invention can be embodied in many different forms, specific preferred embodiments of the present invention are described in detail herein. The present disclosure is an example of the principles of the present invention and is not intended to limit the present invention to the specific embodiments shown. In addition, unless explicitly stated to the contrary, the use of the term "one" is intended to include "at least one" or "one or more". For example, "a device" is intended to include "at least one device" or "one or more devices".

[0104] Any range given in absolute terms or approximate terms is intended to encompass both, and any definition used herein is intended to illustrate rather than limit. Although the numerical ranges and parameters describing the broad scope of the present invention are approximate, the numerical values ​​described in the specific examples are reported as accurately as possible. However, any numerical value inherently contains certain errors caused by the standard deviation found in its corresponding test measurement. In addition, all ranges disclosed herein are understood to encompass any and all subranges (including all fractional values ​​and entire values) contained therein.

[0105] In addition, the present invention encompasses any and all possible combinations of some or all of the various embodiments described herein. It should also be understood that the various changes and modifications made to the current preferred embodiments described herein are obvious to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the present invention and without reducing its expected advantages. Therefore, the appended claims are intended to cover such changes and modifications.

Claims

1. A method for producing chlorine dioxide, the method comprising: feeding a first solution comprising an acid into a mixing device through a first feed line; feeding a second solution comprising chlorite or chlorate into the mixing device through a second feed line; mixing the first solution and the second solution in the mixing device to form a reaction mixture, wherein the mixing device is in fluid communication with a separator; feeding the reaction mixture into the separator; directing the reaction mixture through the separator in a spiral path; reacting the acid with the chlorite or the chlorate in the separator to produce gaseous chlorine dioxide, wherein a liquid comprising the product and unreacted chemicals accumulates at the bottom of the separator, and wherein the separator is in fluid communication with a product line for withdrawing gaseous products; and The gaseous chlorine dioxide is withdrawn from the separator into the product line; wherein the residence time of the reaction mixture in the separator is at least 10 minutes; and wherein the separator is operated at a pressure less than atmospheric pressure.

2. The method of claim 1, wherein the acid is hydrochloric acid, phosphoric acid, sulfuric acid, hypochlorous acid, or any combination thereof.

3. The method of claim 1, wherein the acid comprises sulfuric acid and the second solution comprises chlorate and hydrogen peroxide.

4. The method of claim 1, wherein the acid comprises hydrochloric acid and the second solution comprises chlorite.

5. The method of claim 1, wherein the helical path is defined by a catheter having a coiled configuration with a coil plane angle of 1 degree to 60 degrees.

6. The method according to any one of claims 2 to 5, wherein the first feed line and the second feed line are opposite to each other and point towards each other.

7. The method of any one of claims 1-5, further comprising generating the chlorine dioxide at a rate in the range of 0.001 lbs / hr to 200 lbs / hr.

8. The method of any one of claims 1-5, further comprising operating the separator at a temperature in the range of 2°C to 80°C.

9. The process according to any one of claims 1 to 5, wherein the reaction mixture is fed into the top part of the separator.

10. The process according to any one of claims 1 to 5, wherein the reaction mixture is fed into the bottom part of the separator.

11. The process according to any one of claims 1 to 5, wherein the reaction mixture is fed into a middle section of the separator.

12. The method of any one of claims 1-5, further comprising extracting liquid from the separator and recycling the liquid to the separator.

13. The method of any one of claims 1-5, wherein the spiral path is defined by a plurality of plates disposed within the separator. The method of claim 13 , wherein the plurality of plates comprises plates having perforations.

15. A method for treating process water, the method comprising: feeding a first solution comprising an acid into a mixing device through a first feed line; feeding a second solution comprising chlorite or chlorate into the mixing device through a second feed line; mixing the first solution and the second solution in the mixing device to form a reaction mixture, wherein the mixing device is in fluid communication with a separator; feeding the reaction mixture into the separator; directing the reaction mixture through the separator in a spiral path; reacting the acid with the chlorite or the chlorate in the separator to produce gaseous chlorine dioxide, wherein a liquid comprising the product and unreacted chemicals accumulates at the bottom of the separator, and wherein the separator is in fluid communication with a product line for withdrawing gaseous products; extracting the gaseous chlorine dioxide from the separator into the product line; as well as injecting the gaseous chlorine dioxide into the process water; wherein the residence time of the reaction mixture in the separator is at least 10 minutes; and wherein the separator is operated at a pressure less than atmospheric pressure.

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