JP2015175551A - Injection method of steam condensate system treatment agent and steam generation plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection method capable of evenly injecting steam condensate system treatment agent to steam while suppressing costs, and a steam generation plant in which steam condensate system treatment agent is evenly injected to steam.SOLUTION: A fuel flow rate flowing in a fuel pipeline is acquired by a flowmeter provided in the fuel pipeline supplying fuel to a boiler, and a discharge amount of a chemical injection pump injecting steam condensate system treatment agent to steam is proportional to the fuel flow rate.

Description

  The present invention relates to a method for injecting a steam condensate treatment agent for preventing corrosion of a steam condensate system in a steam generation plant. The present invention also relates to a steam generation plant in which a steam condensate system is protected from corrosion.

  As a steam condensate anticorrosion method for steam generating equipment, as a steam condensate chemical, a neutral amine such as monoethanolamine, cyclohexylamine, morpholine is added to the steam to increase the pH of the condensed water to prevent corrosion Alternatively, a method of forming a water-repellent film on a metal surface in a steam condensate piping by adding a long-chain alkylamine such as octadecylamine called a film-forming amine to the steam has been widely performed.

  In general, as a method for controlling the addition of steam condensate treatment agents using volatile substances such as neutralizing amines and film-forming amines, a microcomputer that determines the operation time of a chemical injection pump according to the combustion state and combustion time of the boiler There has been performed a method of interlocking and proportionally controlling a chemical injection pump by control, a feed water pump on / off signal or a pulse signal. Moreover, the chemical injection point was installed in the water supply line or the steam header, and the volatile component was transferred to the steam process side by heating the steam condensate treatment agent in the boiler or the steam header.

  However, conventional neutralizing amine alone treatment is uneconomical because it requires a large amount of addition to raise the pH and suppress corrosion in the soft water feed steam generation facility. Further, when a large amount of neutralizing amine is mixed in steam or condensed water, there is a problem in that it adversely affects the steam use process and waste water.

  Further, in the conventional film-forming amine treatment, if the film-forming amine is added excessively and becomes a high concentration, there is a possibility that the steam trap, the orifice or the like may be clogged, and the amount of addition cannot be increased to increase the anticorrosion effect. was there.

  With respect to these problems, Patent Document 1 proposes a method of using an emulsified emulsion of vegetable oil as an anticorrosive agent. By using such an anticorrosive agent, an excellent anticorrosive effect is exhibited with respect to low-concentration steam condensate steel and copper.

JP 2013-19042 A

  Steam condensate treatment agents using emulsions of vegetable oils and fats are non-volatile, and are added directly to the steam pipes and used by diffusing chemical components in the steam by the flow of steam. It is necessary to inject continuously and in proportion to the steam flow rate. In the conventional microcomputer control and the interlocking / proportional control of the medicinal pump by the on / off signal of the feed water pump, the interval between medicinal injections is long and irregular. Therefore, when a conventional chemical addition method is used, there is a problem in that a non-volatile steam condensate treatment agent cannot be uniformly added to continuously generated steam and a sufficient anticorrosion effect may not be obtained. there were. When a steam flow meter is installed in the steam pipe, it is preferable to add a non-volatile steam condensate treatment agent to the steam pipe based on the output signal of the steam flow meter, but the steam flow meter is expensive. It is often not installed, and installing a new steam flow meter is expensive.

  The present invention has been made in view of the above-described conventional situation, and an injection method capable of uniformly injecting a steam condensate treatment agent into steam while suppressing costs, and a steam condensate treatment agent with respect to steam. It is an object to provide a steam generation plant that is uniformly injected.

  A method for injecting a steam condensate treatment agent according to the present invention is a method for injecting a steam condensate treatment agent into steam generated in a boiler, from the flow meter provided in a fuel pipe for supplying fuel to the boiler. A flow rate of fuel flowing through the pipe is acquired, and a discharge amount of a chemical injection pump that injects the steam condensate treatment agent into the steam is proportional to the fuel flow rate.

  The steam condensate treatment agent injection method of the present invention is a method of injecting steam condensate treatment agent into steam generated in a boiler, and obtains steam pressure from a pressure sensor provided in a steam pipe through which the steam flows. The chemical injection pump for injecting the steam condensate treatment agent into the steam is operated when the steam pressure is equal to or higher than a predetermined value, and the chemical injection pump is stopped when the steam pressure is lower than the predetermined value.

  In one aspect of the present invention, it is preferable to inject the steam condensate treatment agent into the steam that has passed through the steam header.

  In one aspect of the present invention, the steam condensate treatment agent is preferably non-volatile.

  The steam generation plant of the present invention includes a boiler that generates fuel by burning fuel, a fuel pipe that supplies fuel to the boiler, a flow meter that is provided in the fuel pipe and measures a fuel flow rate, and a chemical tank. A chemical injection pump for injecting the stored steam condensate treatment agent into the steam, and a controller for controlling the discharge amount of the chemical injection pump in proportion to the fuel flow rate.

  In one aspect of the present invention, a plurality of boilers are provided, the fuel pipe branches to supply fuel to each boiler, and the flowmeter is provided upstream of a branch point of the fuel pipe. It is preferable.

  The steam generation plant of the present invention includes a boiler that generates fuel by burning fuel, a pressure sensor that measures steam pressure provided in a steam pipe through which the steam flows, and a steam condensate treatment stored in a chemical tank. A chemical injection pump for injecting a drug into the steam; and a control unit that operates the chemical injection pump when the vapor pressure is equal to or higher than a predetermined value and stops the chemical injection pump when the vapor pressure is lower than the predetermined value; .

  In one aspect of the present invention, it is preferable that the apparatus further includes a steam header to which steam generated in the boiler is supplied, and the chemical injection pump injects the steam condensate treatment agent into the steam after passing through the steam header.

  In one aspect of the present invention, it is preferable that the steam after passing through the steam header flows through a vertical pipe and a horizontal pipe, and the chemical injection pump injects the steam condensate treatment agent into the steam flowing through the horizontal pipe.

  According to the present invention, by making the discharge amount of the chemical injection pump proportional to the fuel flow rate, the injection amount of the steam condensate treatment agent is substantially proportional to the steam flow rate, and the steam condensate treatment agent is uniformly injected into the steam. be able to. When multiple boilers are provided and fuel pipes are branched and fuel is supplied to each boiler, a flow meter is provided upstream from the branch point of the fuel pipes, so that multiple boilers proportional to the steam flow rate can be provided. The total fuel flow supplied can be measured.

  In the present invention, by injecting a steam condensate treatment agent into the steam after passing through the steam header, the steam condensate treatment agent is prevented from being discharged in a large amount by a steam trap, etc. The anti-corrosion effect of the steam condensate treatment agent can also be efficiently exhibited in the piping and steam equipment. Moreover, it is preferable to inject | pour a steam condensate type processing agent with respect to the steam which flows through horizontal piping.

  According to the present invention, when the steam flow rate is substantially constant, the steam condensate treatment agent can be uniformly injected into the steam by controlling the operation / stop of the chemical injection pump based on the steam pressure.

It is a schematic block diagram of the steam generation plant which concerns on embodiment of this invention. It is a schematic block diagram of the steam generation plant by a 1st modification. It is a schematic block diagram of the steam generation plant by the 2nd modification. It is a schematic diagram of the steam generation plant in the Example of this invention.

  Hereinafter, embodiments of the present invention will be described in detail.

  FIG. 1 is a schematic configuration diagram of a steam generation plant according to an embodiment of the present invention. As shown in FIG. 1, the steam generation plant includes a boiler 10 that burns fuel to generate steam, a load device 14 that is driven by steam supplied from the boiler 10 via a steam header 12, and exhaust steam from the load device 14. And a heat exchanger 16 that generates condensed water (condensate). In the steam generation plant, a chemical tank 30 for storing the steam condensate treatment agent, a chemical injection pump 32 for injecting the steam condensate treatment agent in the chemical tank 30 into the steam, and a control unit for controlling the chemical injection pump 32. 40 is provided.

  Fuel is supplied to the boiler 10 via a fuel pipe L1. The fuel pipe L1 is provided with a flow meter 20 for measuring the fuel flow rate. For example, when the fuel is a liquid fuel such as heavy oil or light oil, an in-line flow meter can be provided in the fuel pipe L1. Further, by using a clamp-on type ultrasonic flow meter as the flow meter 20, the flow meter 20 can be installed in the fuel pipe L1 without piping work.

  The measurement result of the flow meter 20 is output to the control unit 40 as a pulse signal or an analog signal. The fuel flow rate measured by the flow meter 20 follows the combustion state of the boiler 10. In other words, the fuel flow rate behaves according to the vapor flow rate. Therefore, the control unit 40 acquires a fuel flow rate measurement result having a value corresponding to the steam flow rate from the flow meter 20.

  The steam generated in the boiler 10 is supplied to the steam header 12 via the steam pipe L4. A steam trap is connected to the bottom of the steam header 12 via a drain discharge pipe (both not shown) so that the condensed water in the steam header 12 can be discharged.

  The steam discharged from the steam header 12 is supplied to the load device 14 through the steam pipe L5. The steam pipe L5 has a horizontal pipe and a vertical pipe, and a steam condensate treatment agent is injected from the chemical injection pump 32 into the steam flowing through the horizontal pipe. The steam condensate treatment agent is injected at a horizontal pipe downstream of the steam header 12 to prevent a large amount of steam condensate treatment agent from being discharged by a steam trap or the like. A condensate treatment agent can be reached.

  The load device 14 is driven by steam supplied via the steam pipe L5. The load device 14 is, for example, a steam turbine or factory equipment. The steam discharged from the load device 14 is condensed by the heat exchanger 16, and the condensed water is collected by the condensate pipe L 6 and mixed with the feed water to the boiler 10.

  The control unit 40 controls the drug injection pump 32 based on the measurement result of the flow meter 20. Specifically, the control unit 40 controls the chemical injection pump 32 so that the injection amount of the steam condensate treatment agent by the chemical injection pump 32 (the discharge amount of the chemical injection pump 32) is proportional to the fuel flow rate.

  The steam condensate treatment agent stored in the chemical tank 30 is preferably an emulsified emulsion of fats and oils, but is not limited thereto. As fats and oils, vegetable oils such as rapeseed oil, sunflower oil, soybean oil, corn oil, sesame oil and olive oil are preferable. It is preferable to emulsify such vegetable oils and fats using a plant-derived ester emulsifier. Such an emulsified emulsion of fats and oils has an excellent anticorrosive effect on the steel pipe and copper pipe constituting the steam pipe L5 and the condensate pipe L6.

  The chemical injection pump 32 has a discharge capacity that satisfies the injection amount of the steam condensate treatment agent corresponding to the maximum fuel flow rate. In addition, the medicine injection pump 32 has a function of operating in proportion and interlocking with an analog signal or a pulse signal output from the flow meter 20. The chemical injection pump 32 is preferably one that can continuously discharge the steam condensate treatment agent for a long time. When a pump that intermittently discharges liquid, such as a plunger pump or a diaphragm pump, is used as the medicine pump 32, the minimum discharge amount that can be controlled is small so that the discharge amount follows the measurement result of the flow meter 20. Those are preferred.

  Thus, according to this embodiment, the fuel flow rate which becomes a value according to the steam flow rate is measured, and the discharge amount of the chemical injection pump 32 is made proportional to the fuel flow rate. Therefore, the injection amount of the steam condensate treatment agent into the steam pipe L5 is substantially proportional to the steam flow rate, and the steam condensate treatment agent can be uniformly injected into the steam. In addition, steam condensate treatment agent can be prevented from being discharged in large quantities by steam traps, etc., and the steam pipe condensate treatment agent can effectively exhibit the anti-corrosion effect of steam condensate treatment agent on steam pipes and steam facilities farther away from the chemical injection point it can. Furthermore, since installation of a steam flow meter and piping work are unnecessary, cost can be suppressed.

  In addition, it can be confirmed by a well-known oil content analysis method whether the steam condensate processing agent has reached the anticorrosion target (for example, the steam pipe L5 and the condensate pipe L6) of the steam generation plant. In this method, first, the condensed water on the downstream side of the anticorrosion target is sampled. For example, drainage discharged from a steam trap (not shown) connected to the steam pipe L5 and condensed water discharged from the heat exchanger 16 are sampled.

  Subsequently, the low temperature hydrophilic-high temperature hydrophobic thermoreversible thermosensitive polymer compound is added to the sampling water. Low-temperature hydrophilic-high-temperature hydrophobic thermoreversible polymer compound is hydrophilic and dissolves in water at a predetermined temperature (transition temperature) or lower, but dehydrates and becomes hydrophobic at a predetermined temperature or higher and becomes compatible with oil. It is a substance that produces sex. When the sampling water to which the low-temperature hydrophilic-high-temperature hydrophobic thermoreversible thermosensitive polymer compound is added is raised above the transition temperature, it becomes dehydrated and becomes hydrophobic, so that it has affinity with the oil. As a result, the oil in the sampling water is taken into the solidified polymer solid (solid) and highly concentrated. In this way, it is also possible to concentrate the oil that exists in an extremely dilute state in water.

  The solid is then separated from the aqueous phase. When a small amount of pure water is added to the obtained solid and the temperature is lower than the transition temperature, the solid is dissolved and the oil is suspended using the aqueous solution of the thermosensitive polymer compound as a dispersion medium. A thermosensitive polymer compound exhibits a surfactant-like property having both hydrophobic and hydrophilic properties, and its aqueous solution forms a micelle including the oil component, whereby the oil component can be suspended and dispersed as small particles. it can. The suspension remains highly stable over time and its turbidity is proportional to the oil content. Moreover, since the suspended particle diameter can be kept small, high sensitivity can be obtained in turbidity measurement. The turbidity in the aqueous suspension is measured, and the oil content is determined based on this turbidity.

  Low-temperature hydrophilicity-High-temperature hydrophobic thermoreversible polymer compound having a transition temperature of about 20 to 60 ° C. can be made hydrophilic by using a water bath or hot water bath for the sample container without using a special device. Or it can change to hydrophobicity. Examples of the low temperature hydrophilic-high temperature hydrophobic thermoreversible polymer compound include N, N-diethylacrylamide, N-isopropylacrylamide, Nn-propylacrylamide, N-cyclopropylacrylamide and the like.

  As a turbidity measurement method, a transmitted light method, a scattered light method, an integrating sphere method, or the like can be used. For example, when the transmitted light method is used, it is desirable that the measurement wavelength is in a wavelength region of 600 nm or more.

  By obtaining the oil content in the sampling water by such a method, it can be confirmed whether the steam condensate treatment agent has reached the anticorrosion target, and chemical management can be easily performed at the installation site of the steam generation plant. .

[First Modification]
Although the said embodiment demonstrated the steam generation plant provided with one boiler 10 as shown in FIG. 1, two or more boilers may be provided. FIG. 2 shows a schematic configuration of a steam generation plant provided with two boilers 10 and 11. The same components as those in the steam plant shown in FIG.

  The fuel pipe L1 branches into fuel pipes L2 and L3. Fuel is supplied to the boiler 10 via the fuel pipe L2, and fuel is supplied to the boiler 11 via the fuel pipe L3. The steam generated in the boiler 10 and the steam generated in the boiler 11 merge and are supplied to the steam header 12 via the steam pipe L4.

  The flow meter 20 is preferably provided in the fuel pipe (base pipe) L1 before branching. By providing the flow meter 20 in the fuel pipe L1, the total fuel flow rate supplied to the plurality of boilers can be measured. This total fuel flow rate becomes a value proportional to the steam flow rate in the steam generating plant, and the control unit 40 controls the discharge amount of the chemical injection pump 32 based on this value, whereby the steam condensate system process to the steam pipe L5 is performed. The injection amount of the agent is substantially proportional to the steam flow rate, and the steam condensate treatment agent can be uniformly injected into the steam.

  A fuel gauge 20 may be provided in each of the branched fuel pipes L2 and L3. In this case, it is preferable that the control unit 40 includes a PLC (Programmable Logic Controller) and a pulse synthesizer, and controls the discharge amount of the chemical injection pump 32 to be proportional to the total value of the measurement results of the fuel gauges 20.

[Second Modification]
In the above embodiment, the discharge amount of the chemical injection pump 32 is controlled so as to be proportional to the fuel flow rate. However, in a steam plant having a substantially constant steam flow rate, the steam pressure is measured, and the measured steam pressure exceeds a predetermined value. Sometimes the steam condensate treatment agent is continuously injected, and when the steam condensate treatment agent becomes less than a predetermined value, the injection of the steam condensate treatment agent may be stopped.

  In many cases, an analog display pressure gauge is installed in the steam pipe, and this pressure gauge line can be branched to install a digital pressure sensor. For example, as shown in FIG. 3, the pressure gauge line of the analog display pressure gauge 22 installed in the steam pipe L <b> 5 on the downstream side of the steam header 12 is branched to install a digital pressure sensor 24. The pressure sensor 24 measures the steam pressure and outputs the measurement result to the control unit 40 as a pulse signal or an analog signal. The maximum value of the measurement range of the pressure sensor 24 is larger than the maximum steam pressure of the boiler 10.

  When the steam pressure rises with the operation of the boiler 10 and the measured value of the pressure sensor 24 reaches a predetermined value, the control unit 40 controls the chemical injection pump 32 to discharge the steam condensate treatment agent. When the boiler 10 stops and the steam pressure decreases and the measured value of the pressure sensor 24 becomes less than a predetermined value, the control unit 40 stops the chemical injection pump 32. As described above, in a steam plant having a substantially constant steam flow rate, the steam condensate treatment agent can be uniformly injected into the steam by controlling the operation / stop of the chemical injection pump 32 based on the steam pressure.

  In FIG. 1 to FIG. 3, the injection site of the steam condensate treatment agent is arranged in the horizontal pipe of the steam pipe L <b> 5 on the downstream side of the steam header 12, but may be arranged in a vertical pipe. Further, when there is no suitable injection location on the downstream side of the steam header 12, the injection location may be arranged in the steam header 12 or the steam pipe L4 on the upstream side of the steam header 12.

  In the embodiment described above, an emulsion of fats and oils is used as the steam condensate treatment agent. However, the present invention is not limited to this, and volatile / nonvolatile chemicals can be used.

  The invention is explained in more detail by means of examples. Note that the present invention is not limited to these examples.

<Experimental conditions>
FIG. 4 is a schematic diagram of the steam generation plant in which the experiment was performed. Two small once-through boilers (Samson NBO-500N) are operated at high combustion operation, steam 920kg / h, fuel consumption 76L / h, operating pressure 0.7MPa, blow rate 5%, feed pump capacity is 1350 L / (h · unit).

As a non-volatile steam condensate chemical, in the presence of 5 parts by mass of 30 parts by mass of coconut oil in 100 parts by mass of an aqueous medium, polyglycerin lauric acid monoester (trade name: SY Glyster, manufactured by Sakamoto Pharmaceutical Co., Ltd.) as an emulsifier, A coconut oil emulsion having an average diameter of about 2 μm of oil droplets prepared by emulsifying 30 parts by mass of coconut oil using a homogenizer (manufactured by IKA, model name: ULTRA-TURRAX T50 basic) was used. The addition amount was 25 g / m ³ for steam, and was injected into a horizontal steam pipe before (upstream side) or after (downstream side) the steam header. The distance between the chemical injection point before the steam header and the chemical injection point after the steam header was 2 m.

  Steam trap drain on the steam header, steam trap drain 5m away from the pouring point after the steam header, and steam condensate after the heat exchanger 30m away, every 10 minutes after 20 hours The concentration of the steam condensate chemicals was compared according to the steam condensate chemical concentration detection method shown below.

  In addition, a part of the steam condensate is branched, and water is continuously passed through the resin column where the test piece (SPCC, # 400 polished and etched) is installed for 24 hours. Corrosion rate was calculated. The amount of cooling water was adjusted to maintain steam condensate at 40 ° C.

<Steam condensate chemical concentration detection method>
(Step 1) The steam trap drain of the steam header, the steam trap drain at a point 5 m away from the chemical injection point after the steam header, and the steam condensate after the heat exchanger 30 m away are sampled. Sampling uses a glass container that is lined in advance so that the volume of the sample required for oil analysis is known, and drain / steam condensate is sampled to that line. If the container to be sampled is different from the measuring container, oil will remain in the sampling container when the container is moved and an error will occur, so the sampling container and the measuring container are preferably the same. In addition, the sampling container has a highly airtight lid.

  (Step 2) If the water temperature of the sampling water is higher than the transition temperature of the low temperature hydrophilic-high temperature hydrophobic thermoreversible polymer compound to be used, it is cooled below the transition temperature. Although the cooling method is not specified, a method such as closing the lid and bathing the entire container is suitable.

  (Step 3) Adjust pH and chloride concentration of sampling water. The reason why the pH and the chloride concentration are adjusted is that the transition temperature of the low temperature hydrophilic-high temperature hydrophobic thermoreversible polymer compound varies depending on the pH and the chloride concentration. Chloride also has the effect of promoting aggregation due to the salting out effect.

  (Step 4) Add low temperature hydrophilicity-high temperature hydrophobic thermoreversible polymer compound to sampling water, close the lid and stir well.

  (Step 5) The sampling water is heated above the transition temperature of the low temperature hydrophilic-high temperature hydrophobic thermoreversible polymer compound. Although the heating method is not specified, a method such as closing the lid and warming the whole sampling container is suitable.

  (Step 6) After the sampling water is sufficiently heated, the sampling container is well stirred, and the low temperature hydrophilic-high temperature hydrophobic thermoreversible polymer compound is reacted with the oil to cause aggregation.

  (Step 7) In order to agglomerate the aggregate, it is allowed to stand for several minutes in an environment higher than the transition temperature.

  (Step 8) Discard the aqueous solution other than the aggregates.

  (Step 9) Add a predetermined amount of pure water to the sample container containing the agglomerates, close the lid and stir well, then cool to below the transition temperature of the low temperature hydrophilic-high temperature hydrophobic thermoreversible polymer compound. Then, the aggregate is dispersed in pure water.

  (Step 10) The spectrophotometer (wavelength 660 nm) of the aqueous solution in which the aggregate is dispersed is measured with a spectrophotometer.

  (Step 11) The steam condensate chemical concentration is calculated from the relationship between the vapor condensate chemical concentration and the spectroscopic degree acquired in advance.

[Example 1]
Installed an ultrasonic flow meter (Tokyo Instruments UL330) in the fuel pipe (fuel type: A heavy oil, pipe diameter: 20A) before branching from the service tank to each boiler, and the fuel detected by the ultrasonic flow meter A flow rate of 0-2500 L / h was set to be output as an analog signal of 4-20 mA. Chemical feed pump (Iwaki, Ltd. EHN-B11VC1YN) the stroke number 0-82% analog signal 4-20mA from ultrasonic flowmeter, by setting the stroke length of 50%, with 25 g / ^{m 3} to the steam It was adjusted so that it could be added. M ³ is Nm ³ (the same applies hereinafter).
The chemical injection point was a horizontal steam pipe (pipe diameter: 40A) after the steam header, and a 6 mm SUS nozzle was inserted from the bottom of the pipe to the center of the pipe, and the chemical was injected from the tip of the nozzle. The results are shown in Table 1.

[Example 2]
Installed an ultrasonic flow meter (Tokyo Instruments UL330) in the fuel pipe (fuel type: A heavy oil, pipe diameter: 20A) before branching from the service tank to each boiler, and the fuel detected by the ultrasonic flow meter A flow rate of 0-2500 L / h was set to be output as an analog signal of 4-20 mA. Chemical feed pump (Iwaki, Ltd. EHN-B11VC1YN) the stroke number 0-82% analog signal 4-20mA from ultrasonic flowmeter, by setting the stroke length of 50%, with 25 g / ^{m 3} to the steam It was adjusted so that it could be added.
The chemical injection point was a horizontal steam pipe (pipe diameter: 40A) in front of the steam header, and a 6 mm SUS nozzle was inserted from the lower part of the pipe to the center of the pipe, and the chemical was injected from the tip of the nozzle. The results are shown in Table 1.

[Example 3]
A pressure sensor (TLV 060G3126) was installed in the steam pipe after the steam header. The analog signal of the pressure sensor is output at 4-20 mA for a steam pressure of 0-1.0 MPa. By setting the chemical injection pump (IHaki EHN-B11VC1YN) to a stroke number of 2.5% and a stroke length of 50% when a signal of 14.4 mA or more corresponding to 0.65 MPa is input as the steam pressure. , And was adjusted so that it could be added at 25 g / m ³ to the steam.
The chemical injection point was a horizontal steam pipe (pipe diameter: 40A) after the steam header, and a 6 mm SUS nozzle was inserted from the lower part of the pipe to the center of the pipe, and the chemical was injected from the tip of the nozzle. The results are shown in Table 1.

[Example 4]
A pressure sensor (TLV 060G3126) was installed in the steam pipe after the steam header. The analog signal of the pressure sensor is output at 4-20 mA for a steam pressure of 0-1.0 MPa. By setting the chemical injection pump (IHaki EHN-B11VC1YN) to a stroke number of 2.5% and a stroke length of 50% when a signal of 14.4 mA or more corresponding to 0.65 MPa is input as the steam pressure. It adjusted so that it could add at 25 g / m < ³ > with respect to steam.
The chemical injection point was a horizontal steam pipe (pipe diameter: 40A) in front of the steam header, and a 6 mm SUS nozzle was inserted from the bottom of the pipe to the center of the pipe, and the chemical was injected from the tip of the nozzle. The results are shown in Table 1.

[Comparative Example 1]
Medicine was injected using the microcomputer control function of the boiler. In the microcomputer control, it is assumed that the steam generation capacity is 460 kg / h in a high combustion state and 230 kg / h in a low combustion state, and the feed water flow rate is assumed by multiplying the operation time in each combustion state. Each boiler has a chemical injection pump (EHN-B11VC1YN manufactured by Iwaki). The operation time is 2.5 minutes and the chemical injection pump (stroke length 50%) is 1.5 seconds for every 19.2 kg of steam flow. It set so that it might operate | move and adjusted the chemical injection quantity so that it might become 25 g / m < ³ > with respect to a vapor | steam.
The chemical injection point is a horizontal steam pipe (pipe diameter: 40A) after the steam header. After connecting the check on the discharge side of the chemical injection pump installed in each boiler to one, 6mm from the bottom of the pipe to the center of the pipe The SUS nozzle was inserted, and the medicine was injected from the tip of the nozzle. The results are shown in Table 1.

[Comparative Example 2]
The drug injection pump was turned on / off in conjunction with the on / off of the water supply pump. A chemical injection pump (EHN-B11VC1YN manufactured by Iwaki) was prepared for each of the two boilers. In order to set the chemical injection amount to 25 g / m ³ with respect to the steam, the stroke length was set to 3.7% and the stroke length was set to 50%.
The chemical injection point is a horizontal steam pipe (pipe diameter: 40A) after the steam header. After connecting the check on the discharge side of the chemical injection pump installed in each boiler to one, 6mm from the bottom of the pipe to the center of the pipe The SUS nozzle was inserted, and the medicine was injected from the tip of the nozzle. The results are shown in Table 1.

  As shown in Table 1, when the chemical injection point is set after the steam header in fuel flow proportional control, the amount of chemical discharged by the steam trap is small, and the amount of chemical that has moved to the end of the steam system along the steam flow is large. Was able to do the drug injection most efficiently. Even when the chemical injection point was set after the steam header in the steam pressure gauge interlocking control, the results were almost the same. If the chemical injection is performed before the steam header, the efficiency of the chemical injection is lower than the case where the chemical injection is performed after the steam header by the same control method, but the chemical injection point is controlled by the microcomputer control and the feed water pump on / off interlock control after the steam header. We were able to inject medicine more efficiently than the case. Thus, by performing the chemical injection by the fuel flow rate proportional control or the steam pressure gauge interlocking control, it is possible to efficiently exert the anti-corrosion effect of the steam condensate system on the steam facility far from the chemical injection point.

DESCRIPTION OF SYMBOLS 10 Boiler 12 Steam header 14 Load apparatus 16 Heat exchanger 20 Flowmeter 30 Chemical solution tank 32 Chemical injection pump 40 Control part

Claims (9)

A method of injecting steam condensate treatment agent into steam generated in a boiler,
Obtaining a flow rate of fuel flowing through the fuel pipe from a flow meter provided in a fuel pipe for supplying fuel to the boiler;
A method of injecting a steam condensate treatment agent, characterized in that a discharge amount of a chemical injection pump for injecting the steam condensate treatment agent into steam is made proportional to the fuel flow rate. A method of injecting steam condensate treatment agent into steam generated in a boiler,
Obtaining a steam pressure from a pressure sensor provided in a steam pipe through which the steam flows;
A chemical injection pump for injecting the steam condensate treatment agent into steam when the steam pressure is a predetermined value or more is operated, and when the steam pressure is less than the predetermined value, the chemical injection pump is stopped. Steam condensate treatment agent injection method.   The method for injecting a steam condensate treatment agent according to claim 1 or 2, wherein the steam condensate treatment agent is injected into the steam after passing through the steam header.   The method for injecting a steam condensate treatment agent according to any one of claims 1 to 3, wherein the steam condensate treatment agent is non-volatile. A boiler that burns fuel and generates steam;
Fuel piping for supplying fuel to the boiler;
A flow meter provided in the fuel pipe for measuring a fuel flow rate;
A chemical injection pump for injecting the steam condensate treatment agent stored in the chemical tank into the steam;
A control unit for controlling the discharge amount of the chemical injection pump so as to be proportional to the fuel flow rate;
A steam generation plant comprising: There are multiple boilers,
The fuel pipe branches to supply fuel to each boiler,
The steam generation plant according to claim 5, wherein the flow meter is provided upstream of a branch point of the fuel pipe. A boiler that burns fuel and generates steam;
A pressure sensor that is provided in a steam pipe through which the steam flows and measures a steam pressure;
A chemical injection pump for injecting the steam condensate treatment agent stored in the chemical tank into the steam;
A control unit that operates the chemical injection pump when the vapor pressure is equal to or higher than a predetermined value, and stops the chemical injection pump when the vapor pressure is lower than the predetermined value;
A steam generation plant comprising: A steam header to which steam generated in the boiler is supplied;
The steam generation plant according to any one of claims 5 to 7, wherein the chemical injection pump injects the steam condensate treatment agent into steam after passing through the steam header. The steam after passing through the steam header flows through a vertical pipe and a horizontal pipe,
The steam generation plant according to claim 8, wherein the chemical injection pump injects the steam condensate treatment agent into steam flowing through the horizontal pipe.

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