JP2006083247A - Corrosion-resistant flow accelerator for cold/hot water and method for accelerating corrosion-resistant flow - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a corrosion-resistant flow accelerator for cold/hot water which inhibits corrosion by using a counterion having a group in a meta- and para-position, not a benzene ring type counterion having a group in an ortho position which may cause metal corrosion, for a cationic surfactant which forms a bar shaped micelle in the presence of the counterion and, at the same time, can be used in a wide range of applications by stabilizing formation of the bar shaped micelle in a high temperature range, and to provide a method for accelerating corrosion-resistant flow of cool/warm water heating medium. <P>SOLUTION: The corrosion-resistant flow accelerator for cold/warm water comprises the cationic surfactant and the counterion of a benzoic acid which is at least either a meta- or a para-halogenated benzoic acid. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention has a drag reduction effect by adding an additive that imparts viscoelastic properties to a heat transfer fluid such as water used in closed circuit circulation systems, district cooling and heating systems, circulation systems of various factories, cogeneration systems, etc. The present invention relates to a corrosion-inhibiting flow promoter for cold / hot water that is induced to turbulently laminarize.

  It is known that a fluid flowing in a pipe such as a pipe has a frictional resistance generated at the fluid and at the boundary between the fluid and the wall of the pipe, and a turbulent flow associated with the resistance. By adding a small amount of a specific substance to the fluid, the flow of the fluid in the pipe becomes smoother or the flow of the fluid in the pipe is reduced. It is known that the ability to resist can be reduced. Substances having such action and effects are referred to in the art as pipe fluids, “flow promoters”, “drag reduction agents”, “friction resistance reduction agents”, “DR agents”, and the like. Air conditioning is indispensable in office buildings, factories, hospitals, department stores, hotels and public facilities. For such air conditioning, a heat transfer system for air conditioning is used. In such a heat transfer system, etc., the length of the pipe is usually long, the resistance in the pipe acting on the fluid flowing in the pipe is large, the fluid conveyance power is also large, and the piping equipment cost is enormous. It will be something. Furthermore, the running cost increases.

  As an advantageous method for reducing the equipment cost and reducing the fluid conveyance power, it has been proposed to use a “flow promoter” that reduces the pipe resistance of fluid such as water flowing in the pipe (for example, patents). Reference 1).

  By the way, cold / hot water pipes for air conditioning equipment, etc., if water management is not performed using a rust inhibitor, etc., will cause rust etc. in the pipes, block the inside of the pipes, damage the pipes themselves, and cause trouble. In the past, various rust prevention and management measures have been taken. Especially in large-scale air-conditioning facilities (such as district cooling and heating, high-rise building air-conditioning) and air-conditioning facilities in semiconductor factories, life extension of piping is regarded as important, and corrosion inhibitors are often used for such purposes. It is a fact. It is said that there are many nitrite-based rust preventives as rust preventives generally used in the sealed cold / hot water path.

Japanese Patent Laid-Open No. 2002-80820

  However, as mentioned above, in recent years, attention has been focused on means for energy saving by circulating cold / hot water added with a surfactant that forms rod-like micelles in the cooling medium transfer pipe and radiator, and further promoting its use. However, in such a flow promoter, a cold / hot water piping system such as an air conditioner includes a steel pipe, a galvanized pipe, a stainless pipe, and a copper pipe is often used for a heat exchange device. In order to suppress the corrosion of these metals, an additive for suppressing the corrosion of each metal is mixed and added.

  These anticorrosives exist in the form of ions in water. On the other hand, surfactants and counter-ionic agents used as flow accelerators are also ionic substances, and when this is mixed with a plurality of rust inhibitors, the flow promotion effect is reduced or the flow promotion effect is obtained. However, there is a problem that the upper limit temperature to be lowered is lowered or corrosion is advanced in some cases. In addition, when the flow accelerator is used alone, corrosion in the pipe is expected to be inevitable, and the pipe wall surface may become uneven due to the occurrence of rust or the like. It is conceivable that the flow is disturbed by the irregularities generated on the inner wall of the pipe, the frictional resistance between the fluid flowing in the pipe and the pipe wall increases, and the flow rate decreases.

  In addition, it is thought that the flow accelerator added to the heat medium is one of the keys to reducing the flow resistance of the fluid flowing in the pipe, but forming rod-like micelles. Is one of the major factors that hinder the reduction of flow resistance.

  The present invention has been made in view of conventional problems, and an object of the present invention is to cause metal corrosion with respect to a cationic surfactant that forms rod-like micelles in the presence of a counterionic agent. By using a counter ion agent with a meta or para group instead of a benzene ring type counter ion agent with an ortho group, the corrosion is suppressed and the formation of rod-like micelles at high temperatures is stabilized. Accordingly, it is an object to provide a corrosion-inhibiting flow promoter for cold / hot water that can be used in a wide range.

  In order to achieve the above object, in the first invention, a cationic surfactant and a counter ion agent that is at least one of meta or para-halogenated benzoic acid are used.

  In the second invention based on the first invention, a rust inhibitor is added to the fluid flow accelerator. Further, in the third invention based on the first invention, an antifoaming agent is added to the fluid flow accelerator. Furthermore, in 4th invention, 50-1500 ppm of cationic surfactants and 50-5000 ppm of counterionic agents were added and mixed with the fluid.

  Addition and mixing of a cationic surfactant with a counter ion agent in the meta or para position into a heat transfer fluid such as water used in closed circuit systems, district heating and cooling systems, circulation systems in various factories, cogeneration systems, etc. By stabilizing the formation of rod-like micelles at high temperatures and laminating turbulent flow, a long-term stable drag reduction effect can be induced, and a heat transfer fluid that can be used in a wide range can be obtained. .

  In the present specification, the “fluid flow promoter” means a substance or composition having a function of making the flow of fluid in the pipe smoother or reducing the force against the flow of the fluid in the pipe. It can be selected from among known ones, preferably those containing a surfactant as a component, more preferably those containing at least a surfactant and a counter ion agent. . The surfactant may be selected from those known to those skilled in the art as a cationic surfactant, and particularly preferably includes a surfactant that forms rod-like micelles in a fluid. For example, a long chain A quaternary ammonium salt having Among these, a quaternary ammonium salt having an alkyl group having 16 to 18 carbon atoms is particularly preferable.

  Suitable cationic surfactants include cetyltrimethylammonium chloride, stearyltrinutylammonium chloride, oleyltrimethylammonium chloride, oleylbishydroxyethylammonium chloride and the like.

The negative ions constituting the quaternary ammonium salt are not particularly limited, and may be halogen ions such as chlorine, bromine and iodine, sulfate ions, nitrate ions, phosphate ions, etc., but chlorine ions are generally used. Is. Next, the counter ion agent is benzoic acid having a substituent at the meta or para position. In particular, metahalogenated benzoic acid or parahalogenated benzoic acid is advantageous, and parachlorobenzoic acid exhibits excellent effects.
One of the features of the present invention is that the benzoic acid used as the counter ion agent has no substituent at the ortho position.

  In the present invention, the use ratio of the cationic surfactant and the counter ion agent is not particularly strict, but as a suitable range, it is used in a ratio of 1 to 3 to 1 by weight. The fluid flow promoter of the present invention is a range in which the cationic surfactant is 50 to 1500 ppm and the counter ion agent is 50 to 5000 ppm with respect to the target heat medium, particularly water or an aqueous solution mainly composed of water. Is preferably used. The use of a larger amount of these cationic surfactants and / or counter-ionic agents leads to an increase in the viscosity of the heat medium, and tends to inhibit the fluid flow. Moreover, if it is used at a concentration lower than the above range, the flow promoting effect is not sufficiently exhibited.

  Assuming zinc-drawing piping, prepare test water in a 500 ml beaker, and pre-weighed zinc plate (30 × 50 × 1 mm) is infiltrated for 12 days. During this period, the sample is stirred with a hot magnet stirrer. The temperature was kept at ℃. Thereafter, the zinc plate was weighed again to determine the weight loss, and the corrosion rate (MDD) of the zinc plate was calculated according to the following formula.

  As a result, data with marked differences in corrosion rates were obtained. That is, as a comparative example, 500 ppm of a cationic surfactant (Arquad 18-63) and 500 ppm of sodium salicylate were added to and mixed with 500 ml of tap water, and the corrosion rate was measured under the above-described conditions. The result was 22.1 (MDD). Incidentally, it is generally judged that the anticorrosion can be achieved when the MDD value is 10 or less. Furthermore, based on the present invention, 500 ppm of cationic surfactant (Arquad 18-63) and 500 ppm of parachlorobenzoic acid were added and mixed, and the corrosion rate of the zinc plate was measured by performing an experiment under the above conditions. When the corrosion rate was calculated by the above, it was 0.1 (MDD), and it was found that the corrosion rate was extremely low. Incidentally, in the case of only 500 ml of tap water, it was 0.5 (MDD).

  In contrast, with existing technologies, sodium molybdate or sodium nitrite can be added to prevent iron corrosion, and benzotriazole-based corrosion inhibitors can be added to prevent copper corrosion. It was not able to be suppressed and there was almost no effect. However, the corrosion resistance to zinc was improved by changing the counterion agent of the drag reducing agent from sodium salicylate to parachlorobenzoic acid. Furthermore, by adding parachlorobenzoic acid, the drag reduction effect is not only at the same level as that by sodium salicylate, but it is also possible to increase the upper limit temperature at which drag reduction is maintained.

  The fluid flow accelerator of the present invention is also extremely effective in combination with a rust inhibitor, and becomes a corrosion-inhibiting flow accelerator for cold and hot water. These rust preventives used in combination are not particularly limited, and commercially available rust preventives can be used. For example, sodium molybdate, potassium molybdate, lithium molybdate, calcium molybdate, molybdenum Examples of the acid ammonium salt include sodium molybdate and lithium molybdate. Examples of the nitrite include sodium nitrite, potassium nitrite, and lithium nitrite. The corrosion-inhibiting flow promoter of the present invention can further contain a benzotriazole-based corrosion inhibitor.

  Although molybdate is generally used as a normal corrosion inhibitor, it is expensive and requires a high amount of addition when used alone. When used in combination with an agent, the corrosion inhibiting activity of the molybdate has only been utilized. As a principle of corrosion inhibition using molybdate in combination with a flow accelerator, molybdate forms an oxide film in the pipe pipe to suppress corrosion, and due to the synergistic effect of adsorption of surfactant, It seems to have brought about a corrosive function. By using the fluid flow accelerator together with the molybdate, the corrosion is always suppressed and the progress of corrosion inside the pipe is eliminated, and the flow promotion function can be maintained for a long time.

  In the present invention, it is also extremely effective to add an antifoaming agent to the fluid flow accelerator in place of the rust inhibitor or in combination with the rust inhibitor. In this case, a commercially available antifoaming agent can be used without any limitation. For example, silicon-based antifoaming agents and mineral oil-based antifoaming agents are commercially available, and these may be used together in an effective amount.

In the typical cold / hot water type air conditioning system of the present invention, the liquid temperature is about −30 to 120 ° C. in the heat medium transfer pipe having a diameter of about 5 to 1000 mm, preferably about 10 to 500 mm, between the heat source point and the heat radiation point. , Preferably about -20 to 100 ° C, more preferably about 2 to 80 ° C, and the parameter chlorobenzoic acid component or metachlorobenzoic acid as the counter ion component is about 50 to 5000 ppm, preferably about 100 to 3000 ppm, More preferably, cold / warm water containing about 200 to 2000 ppm and further containing a rust inhibitor containing molybdate or nitrite is circulated at a wall shear rate of about 5 to 3000 γ (1 / s).
In the present invention, the liquid temperature is limited to about −30 to 120 ° C. for the following reason. That is, when it becomes -30 degrees C or less, a solubility will fall and what once melt | dissolved will elute. Moreover, when it becomes 120 degreeC or more, a rod-like micelle will not be formed or it will be in an unstable state easily.

  In addition, although a heat medium may freeze when it is 0 degrees C or less, in that case, although the solution which added polyethyleneglycol and alcohols is used, the fluid flow promoter of this invention is effective also with respect to this solution. It is. Furthermore, in the case of a high temperature exceeding 100 ° C., naturally, the pressure becomes high, but the fluid flow accelerator of the present invention is also applicable. However, the range in which the flow promoter of the present invention works most effectively is 2 to 80 ° C. as described above.

  The diameter of the transfer pipe for the cold / hot water as the heat medium is preferably about 5 to 1000 mm, more preferably about 10 to 500 mm. Supply becomes difficult, and if this range is exceeded, the piping cost becomes too high.

  In FIG. 2, the vertical axis represents the maximum DR% (%), and the horizontal axis represents the cationic surfactant concentration (ppm). In FIG. 2, the cationic surfactant (surfactant component), which is the fluid flow promoter of the present invention, can be contained in an amount of about 50 to 1500 ppm, preferably about 100 to 1200 ppm, more preferably about 200 to 1500 ppm. If it is less than this range, the drag reduction effect will be unsatisfactory, and if it exceeds this range, the heat quantity will not increase due to the increase in viscosity of the heat medium, and the cost will increase due to the increase in the amount of use. It becomes a problem.

  Further, in FIG. 3, the vertical axis represents the maximum DR% (%), and the horizontal axis represents the counter ion concentration (ppm). In FIG. 3, the preferred range of the counter ion concentration is about 50 to 5000 ppm, and the more preferred range is about 100 to 3000 ppm. If it is less than this range, the drag reduction effect will be unsatisfactory, and if this range is exceeded, the amount of heat will not increase due to the increase in viscosity of the heating medium, and the cost will increase due to the increase in usage. It becomes.

  The present invention will be described in detail with reference to the following examples, which are provided merely for the purpose of illustrating the present invention and for reference to specific embodiments thereof. These exemplifications are for explaining specific specific embodiments of the present invention, but are not intended to limit or limit the scope of the invention disclosed in the present application. In the present invention, it should be understood that various embodiments based on the idea of the present specification are possible. All examples were performed or can be performed using standard techniques, except as otherwise described in detail, and are well known and routine to those skilled in the art. .

  Example 1 will be described with reference to FIG. FIG. 1 shows a cold / hot water type air conditioning system. In FIG. 1, a cold / hot water generator (heat pump) 1 and an elevated tank 2 are connected by a heat medium transfer pipe 3 to test the drag reduction effect and the corrosivity improvement of the heat medium (cold / warm water). The apparatus shown in FIG. 1 is provided with an electromagnetic flow meter 4 and a differential pressure measuring device (U-shaped manometer) 5, which can measure each flow rate and pressure loss in the straight pipe section L between taps. The frequency of the circulation pump 6 was changed by the inverter 7, and the influence of each flow rate, each temperature, and the added flow promoter for fluid and a rust inhibitor containing molybdate or nitrite was examined. In the figure, 8 is a temperature control device, T.I. C is a thermometer. As the cold / hot water generator (heat source) 1, an absorption cold / hot water generator (heat pump) was used. As the circulation pump 6, an S-type single suction centrifugal pump 1.5 kw was used, and the heat medium transfer pipe 3 having a pipe diameter of 20 mm was used. The total length of the heat medium transfer pipe 3 was 220 m. The amount of water retained in the air conditioning system is approximately 1.54 cubic meters. The inverter 7 used was a general-purpose inverter 2.2 kw, and the temperature range of the cold / hot water was 7-10 ° C. cold water and 80 ° C. hot water.

Tap water, 500 ppm of oleyl bishydroxyethylmethylammonium chloride ("Ethoquad O / 12", a product of a surfactant manufactured by Lion Corporation) as a flow promoter for fluids, and a counter ion component The same amount of 500 ppm of parachlorobenzoic acid was added. Sodium molybdate as a rust preventive agent was added to the obtained Ethoquaard O / 12 + parachlorobenzoic acid to reduce drag (drag
The effect on reduction (DR) was examined.

  In the experiment, tap water is used first, it is operated as if it is actually operating, the motor speed is controlled by an inverter, the motor speed of the pump is controlled at each frequency, The pump discharge pressure, the temperature of the heat medium (cold / warm water), and the flow velocity (u [m / s]) were measured for each rotation speed. Next, tap water to which a fluid flow accelerator was added, a fluid flow accelerator and sodium molybdate were added, and the same measurement was performed. In addition, the frequency was lowered using an inverter, the flow rate was set to be the same as that for tap water, and the current value at that time was compared to determine the amount of saving.

The obtained results are shown in FIGS. 4 and 5, the vertical axis represents drag reduction effect (hereinafter referred to as DR%, which is an abbreviation for Drag Reduction Rate), and the horizontal axis represents temperature (° C.). Here, the drag reduction rate DR% (%) was introduced. From the relationship between the fluid friction coefficient f and the Ray nozzle number Re, the fluid friction resistance fw when water (Newtonian fluid) is flowed and the fluid friction resistance fs when a flow accelerator is flowed are calculated, and the drag reduction rate is calculated. DR (%) is defined as follows.
Drag reduction rate DR% (%) = [(fw−fs) / fs] × 100

That is, when there is no drag reduction, the drag reduction rate DR (%) = 0%, and the drag reduction effect increases as the drag reduction rate DR% (%) increases. When FIG. 4 is compared with FIG. 5, in the case of FIG. 4, the cationic surfactant [Ethoquad O / 12; oleylbishydroxyethylmethylammonium chloride; C ₁₈ H ₃₅ N (C ₂ H ₄ OH) ₂ CH ₃ Cl ] After adding sodium salicylate (HOC ₆ H ₄ COONa) to 500 ppm and gradually increasing the temperature from room temperature, the drag reduction rate DR% (%) was measured. As a result, if the fluid temperature exceeded 65 ° C, the drag The decrease rate DR% (%) began to decrease, and the upper limit temperature when the drag decrease rate DR% (%) fell below 50% was 69 ° C.

On the other hand, in the case of FIG. 5, a cationic surfactant (Ethoquad O / 12; oleylbishydroxyethylmethylammonium chloride; C ₁₈ H ₃₅ N (C ₂ H ₄ OH) ₂ CH ₃ Cl) is added to 500 ppm of parachloro. This is the result when benzoic acid (ClC ₆ H ₄ COOH) is added, and the drag reduction rate DR% (%) starts to drop when the temperature exceeds 70 ° C., and the drag reduction rate DR% = 50% at 76 ° C. As a result, it was found that the upper limit temperature was increased by 7 ° C. by changing the counter ion agent from sodium orthosalicylate in the ortho position to parachlorobenzoic acid in the para position.

It is a schematic diagram of the apparatus used for DR effect evaluation using a heat pump. It is a graph which shows the relationship between maximum DR% (%) and a cationic surfactant density | concentration. It is a graph which shows the relationship between maximum DR% (%) and counter ion concentration. It is a graph in the case where the drag reduction rate DR% (%) starts to decrease when the upper limit temperature of the fluid exceeds 69 ° C. It is a graph in the case where the drag reduction rate DR% (%) starts to decrease when the upper limit temperature of the fluid exceeds 76 ° C.

Explanation of symbols

1 Cold / hot water generator (heat pump)
2 Elevated tank 3 Heat transfer pipe 4 Electromagnetic flow meter 5 Differential pressure measuring instrument 6 Circulating pump 7 Inverter 8 Temperature controller

Claims (4)

  A fluid flow accelerator comprising a cationic surfactant and a counter ion agent which is at least one of meta or para-halogenated benzoic acid.   2. The corrosion-inhibiting flow accelerator for cold / hot water according to claim 1, wherein a rust inhibitor is added to the fluid flow accelerator.   The anti-foaming agent for cold / hot water according to claim 1, wherein an antifoaming agent is added to the fluid flow accelerator.   A method for promoting corrosion inhibition in a cold / warm water heating medium, wherein 50 to 1500 ppm of a cationic surfactant and 50 to 5000 ppm of a counter ion agent are added to and mixed with the fluid.

Images