Method for injecting drug into a steam system

Abstract

The invention relates to a method for injecting medicine into a steam system, in particular to a method for injecting medicine into a steam system, which is used for controlling the injection of water treatment medicine into the steam system, the method for injecting the medicine into the steam system controls the injection of the water treatment medicine by the medicine injection pump according to the following contents: a pressure sensor, a temperature sensor or a steam trap which is arranged in the steam system and serves as a steam circulation detection mechanism; a drug injection pump for injecting a water treatment drug into the steam system; and the steam circulation detection condition of the steam circulation detection mechanism.

Description

Technical Field

[0001] The invention relates to a medicine injection method for injecting medicine into a steam system. Background Art

[0002] Chemicals are injected into the steam system to protect the gas supply pipes and equipment using steam generated from the boiler (steam generator) or to maintain efficiency.

[0003] Generally, the purpose of injecting chemicals into a steam system is to prevent corrosion of the steam condensate water system of the steam generating equipment and to improve the heating efficiency of the heat exchanger.

[0004] In order to prevent corrosion of the steam condensate water system of the steam generating equipment, sometimes volatile neutralizing amines such as morpholine or anti-corrosion ingredients such as film amines are added separately to the boiler water supply or condensate system or make-up water system, or boiler chemicals are added that are made by combining volatile neutralizing amines or film amines with the boiler's own anti-corrosion agent to form a single liquid.

[0005] In such a case, a portion of the corrosion inhibitor remains in the boiler water, so it is necessary to add too much chemical, which is not economical. In addition, sometimes, in a system where the chemical is not expected to be present in the steam (for example, a steam humidification system or a process that performs direct steam heating), the chemical is also present in the steam.

[0006] Therefore, these corrosion inhibitors are sometimes directly added to the steam system (Patent Document 1).

[0007] Here, a certain amount of corrosion inhibitor is often injected without installing an expensive steam flow meter on the steam line or installing an interlock for the chemical injection device. In such a case, even if the target equipment stops and steam does not flow, the corrosion inhibitor continues to be injected, and when steam is introduced again, the high-concentration chemical diffuses in the system at a high concentration, which may cause odor failures, etc.

[0008] Furthermore, when boiler steam is branched for use, even if the target equipment is stopped and steam does not flow, the corrosion inhibitor continues to be injected. When steam is introduced again, the high-concentration chemical diffuses in the system at a high concentration, which may cause odor failures, etc.

[0009] In order to improve the heating efficiency of a steam-type heat exchanger, a chemical such as polyamine is sometimes used (Patent Document 2).

[0010] In this case, there is no steam flow meter, and even when the target equipment is stopped, the interlock of the chemical injection device cannot be used, resulting in excessive addition of chemical, sometimes causing odor failure or clogging of the filter (strainer) due to the generation of sticky substances.

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: Japanese Patent Application Publication No. 2004-69182.

[0014] Patent document 2: Japanese Patent Application Publication No. 2019-56524. Summary of the invention

[0015] Problems to be solved by the invention

[0016] The present invention has been made in view of the above-mentioned conventional actual situation, and an object of the present invention is to provide a chemical injection method capable of appropriately injecting the chemical into a steam system while suppressing the cost.

[0017] Means for solving problems

[0018] The gist of the present invention is as follows.

[0019] [1] A method for injecting chemicals into a steam system, which is a method for injecting chemicals into a steam system by controlling the injection of water treatment chemicals into the steam system, wherein the method for injecting chemicals into a steam system controls the injection of the water treatment chemicals using a chemical injection pump according to the following contents: a pressure sensor, a temperature sensor or a steam trap (Steam Trap) provided in the steam system as a steam circulation detection mechanism; a chemical injection pump for injecting water treatment chemicals into the steam system; and the steam circulation detection status of the steam circulation detection mechanism.

[0020] [2] The method for injecting drugs into a steam system as described in [1] is characterized in that the steam circulation detection mechanism is a sensor composed of the pressure sensor or the temperature sensor, and when the detection value of the sensor is above the threshold value, the drug injection pump is operated, and when the detection value of the sensor is less than the threshold value, the drug injection pump is stopped.

[0021] [3] The method for injecting chemicals into a steam system as described in [1] is characterized in that the steam circulation detection mechanism includes the steam trap and a steam circulation detection sensor of the steam trap, and the chemical injection pump is operated when the steam circulation detection sensor detects steam circulation, and the chemical injection pump is stopped when the steam circulation detection sensor does not detect steam circulation.

[0022] [4] The method for injecting chemicals into a steam system as described in any one of [1] to [3] is characterized in that an anti-siphon check valve is provided in the chemical injection piping that guides the water treatment chemical from the chemical injection pump to the steam system.

[0023] [5] A method for injecting chemicals into a steam system as described in any one of [1] to [4], characterized in that the location where the steam circulation detection mechanism is installed in the steam system and the injection point of the water treatment chemical from the chemical injection pump into the steam system are located on the secondary side of a steam flow regulating valve installed in the steam system.

[0024] [6] The method for injecting chemicals into a steam system as described in any one of [1] to [5] is characterized in that at the injection point of the water treatment chemical from the chemical injection pump into the steam system, the water treatment chemical is sprayed into the steam system using a spray nozzle.

[0025] [Effects of the Invention]

[0026] Steam systems are usually pressurized or heated by steam during the operation of boilers and heat exchangers, so their pressure and temperature are high. However, when the boiler stops operating, the temperature of the steam system drops, the volume of steam in the steam system decreases, or the steam condenses into water, so the pressure of the steam system drops significantly.

[0027] In the present invention, a steam circulation detection mechanism is provided in the steam system, and the injection of water treatment chemicals is controlled according to the steam circulation conditions detected by the steam circulation detection mechanism.

[0028] In one embodiment of the present invention, a pressure sensor or a temperature sensor is provided in the steam system, and the drug injection pump is operated when the detection value of the pressure sensor or the temperature sensor is above the threshold value, and the drug injection pump is stopped when the detection value of the sensor is less than the threshold value.

[0029] In another embodiment of the present invention, the steam circulation detection mechanism of the steam system includes a steam trap and a steam circulation detection sensor of the steam trap, and the drug injection pump is operated when the steam circulation detection sensor detects steam circulation in the steam trap, and the drug injection pump is stopped when the steam circulation detection sensor does not detect steam circulation.

[0030] According to the present invention, by stopping the addition of water treatment chemicals to the steam system when the steam supply to the steam system is stopped, a malfunction caused by adding too much chemicals can be prevented from occurring. In addition, since it is possible to prevent the addition of excessive chemicals when the equipment is stopped, it is also advantageous from the viewpoints of economy and feasibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a system diagram of the boiler system according to the embodiment.

[0032] Figure 2 It is a system diagram of the boiler system according to the embodiment.

[0033] Figure 3 It is a system diagram of the boiler system according to the embodiment.

[0034] Figure 4 It is a system diagram of the boiler system according to the embodiment. DETAILED DESCRIPTION

[0035] In the present invention, the steam system may include, but is not limited to, pipes or headers for conveying steam from a boiler or the like, and heat exchangers for supplying steam.

[0036] In one embodiment of the method for injecting chemicals into a steam system of the present invention, a pressure sensor or a temperature sensor is provided in a steam system for delivering steam into a manufacturing process, a chemical injection pump is used to inject water treatment chemicals into the steam system, and a chemical injection control device is used to control the injection of water treatment chemicals according to the signal of the pressure sensor or the temperature sensor, and the addition amount of the chemical injection pump is adjusted according to the detection value of the pressure sensor or the temperature sensor.

[0037] In one embodiment of the present invention, the following ON / OFF control is performed: when the detection value of the pressure sensor or the temperature sensor is above a preset threshold value, the drug injection pump is turned on (ON); when the detection value of the pressure sensor or the temperature sensor is below the threshold value, the drug injection pump is turned off (OFF).

[0038] In another embodiment of the present invention, the steam circulation detection mechanism of the steam system includes the steam trap and a steam circulation detection sensor of the steam trap, and the chemical injection pump is operated when the steam circulation detection sensor detects steam circulation of the steam trap, and the chemical injection pump is stopped when the steam circulation detection sensor does not detect steam circulation.

[0039] As the steam trap, any type of steam trap such as a mechanical steam trap, a thermostatic steam trap, or a thermodynamic steam trap can be used.

[0040] Examples of the mechanical steam trap include a bucket-type mechanical steam trap and a float-type mechanical steam trap with a rod.

[0041] Examples of the thermostatic steam trap include a bellows type thermostatic steam trap and a bimetal type thermostatic steam trap.

[0042] Examples of the thermodynamic steam trap include a disc type thermodynamic steam trap and an air insulation type thermodynamic steam trap.

[0043] As a steam flow detection sensor for detecting that steam flows through a steam trap, a vibration sensor that detects vibrations generated as the steam trap is opened / closed, a temperature sensor that detects the temperature of the steam trap that rises as steam flows through the steam trap, and an acoustic sensor that detects sounds generated from the steam trap due to the flow of steam through the steam trap can be used.

[0044] In the present invention, in order to prevent excess chemicals from being sucked into the steam system even when the steam system is at negative pressure when the equipment is stopped, it is preferred to provide an anti-siphon check valve in the chemical injection line from the chemical injection pump to the chemical injection point.

[0045] In one aspect of the present invention, the pressure sensor, the temperature sensor, the steam trap and the chemical injection point are arranged on the secondary side (downstream side in the steam flow direction) of the steam flow control valve arranged in the steam system.

[0046] Furthermore, in the case where water treatment chemicals are added to the entire steam flow from the boiler rather than to a part of the steam system, the boiler is sometimes operated in a daily late night start / stop operation (Daily Start and Stop, DSS) or weekend start / stop operation (Weekly Start and Stop, WSS). In the DSS or WSS, when the addition of water treatment chemicals to the steam system is stopped when the boiler is stopped, the pressure sensor, temperature sensor, steam trap or chemical injection point can be set outside the secondary side of the steam flow regulating valve. For example, the pressure sensor, temperature sensor, steam trap or chemical injection point can also be set before and after the main steam valve immediately after the boiler body, the steam main pipe or immediately before the heat exchanger.

[0047] The pressure sensor and the drug injection point can be close or far away. In addition, when a plurality of heat exchanger devices are provided and each operates independently, it is ideal to separately provide the pressure sensor and the drug injection point.

[0048] The drug is preferably in the form of a solution or dispersion and delivered to the drug injection point by a drug injection pump.

[0049] In one aspect of the present invention, a water treatment chemical is sprayed at a chemical injection point using a spray nozzle and diffused into a steam system.

[0050] In the present invention, in order to prevent the check valve and the chemical injection piping (hose) from being deteriorated by the heat of the steam system, it is desirable to place them at a sufficient distance from the steam system, or to provide a loop portion in the middle of the chemical injection piping.

[0051] Examples of water treatment chemicals added to the steam system include corrosion inhibitors described in Patent Document 1 and heating efficiency improvers described in Patent Document 2.

[0052] Specifically, the corrosion inhibitor may be any of a film-type corrosion inhibitor that forms a film on the pipe to prevent corrosion, a neutralization-type corrosion inhibitor that neutralizes acidic substances contained in water to prevent corrosion, and a composite corrosion inhibitor that combines a film-type corrosion inhibitor with a neutralization-type corrosion inhibitor.

[0053] Examples of the heating efficiency enhancer include long-chain fatty acid amines, for example, polyamines represented by the following general formula (1).

[0054] R 1 -[NH-(CH2) m ] n -NH2(1)

[0055] In formula (1), R1 represents a saturated or unsaturated hydrocarbon group having 10 to 22 carbon atoms, m is an integer of 1 to 8, and n is an integer of 1 to 7. When n is 2 or more, the plurality of NH-(CH2) m Can be the same or different.

[0056] Hereinafter, the embodiments will be described in more detail with reference to the drawings.

[0057] Figure 1 This is a configuration diagram of a boiler system to which the chemical injection method for a steam system according to an embodiment is applied.

[0058] exist Figure 1 In the embodiment, steam from a boiler 1 is transported by a pipe 2 , passes through a flow rate regulating valve 3 , and is transported to a heat exchanger 5 via a pipe 4 .

[0059] The chemical liquid in the chemical tank 10 is supplied to a chemical injection nozzle (not shown) of the pipe 4 via a chemical injection pump 11 , a pipe 12 , an anti-siphon check valve 13 , and a pipe 14 , and is sprayed into the pipe 4 to inject the chemical.

[0060] The pipe 4 is provided with a pressure sensor 15 , and a detection signal thereof is input to a controller 16 , which controls the chemical injection pump 11 .

[0061] The controller 16 performs on / off control such that the drug injection pump 11 is turned on when the detection value of the pressure sensor 15 is greater than a preset threshold value, and is turned off when the detection value of the pressure sensor 15 is less than the threshold value.

[0062] Furthermore, one drug infusion pump may be controlled based on the detection signal of one pressure sensor, or a plurality of drug infusion pumps may be controlled based on the detection signal of one pressure sensor.

[0063] The same applies to the case where a temperature sensor is used instead of the pressure sensor 11 .

[0064] Figure 2 This is a structural diagram of a boiler system to which a chemical injection method according to another embodiment is applied.

[0065] Said Figure 2In the embodiment, the pressure sensor 15 is omitted. In the embodiment, a steam trap 18 is provided in the piping 17 for steam on the secondary side, i.e., the downstream side, of the heat exchanger 5, and a steam flow detection sensor 19 of the steam trap 18 is provided in the steam trap 18. The detection signal of the steam flow detection sensor 19 is input to the controller 16. The controller 16 operates the chemical injection pump 11 when the steam flow detection sensor 19 detects the flow of steam from the steam trap 18, and stops the chemical injection pump 11 when the steam flow detection sensor 19 does not detect the flow of steam.

[0066] As the steam circulation detection sensor 19, as described above, a vibration sensor, a temperature sensor, an acoustic sensor, or the like can be used. The vibration sensor detects vibration generated due to the opening / closing of the steam trap 18, the temperature sensor detects the temperature of the steam trap 18 that rises due to the circulation of steam into the steam trap 18, and the acoustic sensor detects sound generated from the steam trap 18 due to the circulation of steam into the steam trap 18.

[0067] Figure 2 Other structures and Figure 1 The same symbol indicates the same part.

[0068] Figure 3 This is a structural diagram of a boiler system to which a chemical injection method according to another embodiment is applied. Figure 3 The boiler system omits Figure 1 The pressure sensor 15 and the controller 16 in the boiler system are replaced by a pressure switch 22.

[0069] exist Figure 3 In the embodiment, one end of a siphon tube 20 is connected to the pipe 4 , and the other end of the siphon tube 20 is connected to a pressure switch 22 via a pipe 21 .

[0070] A pipe 23 is branched from the pipe 21, and an exhaust valve 24 is provided at the front end of the pipe 23. Although not shown in the figure, a pressure gauge is provided on the pipe 21.

[0071] The pipe 14 that guides the chemical solution from the chemical injection pump 11 is connected to the pipe 21 .

[0072] The siphon tube 20 is provided to reduce heat transmitted from the pipe 4 to the pressure switch 22 and the check valve 13 to protect them.

[0073] Figure 3 Other structures and Figure 1 The same symbol indicates the same part.

[0074] In the Figure 3 When the pressure transmitted to the pressure switch 22 via the piping 21 is above a predetermined pressure, the pressure switch 22 operates the drug injection pump 11, and when the pressure is lower than the predetermined pressure, the drug injection pump 11 is stopped.

[0075] exist Figure 3 In the embodiment, the pipe 14 for drug injection is connected to the pipe 21, but it can also be as follows Figure 4 The pipe 14 is configured to directly inject the chemical into the pipe 4 via the siphon tube 25 . The siphon tube 25 is provided to reduce the heat transfer from the pipe 4 to the check valve 13 .

[0076] Figure 4 Other structures and control methods of the drug injection pump 11 and Figure 3 The same symbol indicates the same part.

[0077] Example

[0078] [Example 1]

[0079] Make it like Figure 1 The boiler system of such a structure is operated at a steam generation rate of 10 g / hr and a normal operating pressure of 0.78 MPa during steady operation from Monday to Friday. The operation of the boiler is stopped on weekends (Saturday and Sunday).

[0080] An 80 mass % aqueous solution of aminomethyl propanol was used as the water treatment chemical in the chemical tank 10. A diaphragm pump was used as the chemical injection pump 11.

[0081] When the pressure detected by the pressure sensor 15 is 0.5 MPa or more, the drug solution is injected at 200 mL / hr, and when the pressure detected by the pressure sensor 15 is less than 0.5 MPa, the drug injection pump 11 is stopped.

[0082] In the first embodiment, when the boiler is stopped on Saturdays and Sundays, the pressure of the steam system is reduced and the chemical injection pump 11 is stopped.

[0083] As a result, since no chemicals were added during the weekend shutdown of the steam equipment, the steam and condensed water did not become smelly at all when the equipment was restarted.

[0084] [Example 2]

[0085] In Example 2, the operation was performed in the same manner as in Example 1 except that the anti-siphon check valve 13 was not provided.

[0086] In the second embodiment, when the boiler was stopped on Saturdays and Sundays, the pressure of the steam system was reduced and the chemical injection pump was stopped. However, since there was no anti-siphon check valve, as the pressure in the steam system was reduced, part of the chemical in the chemical tank was sucked in due to the negative pressure, and as a result, 1 liter of chemical was added to the system. As a result, the steam and condensed water when the system was restarted became slightly smelly.

[0087] [Comparative Example 1]

[0088] In Comparative Example 1, the pressure is not involved in the detection of the pressure sensor 15, and even when the boiler is stopped, the drug injection pump 11 always injects drugs at 200mL / hr. Therefore, the drugs are continuously injected when the boiler is stopped on Saturdays and Sundays (weekends). In addition, as the equipment is stopped on weekends, the boiler operation is also stopped, so the pressure in the system drops to negative pressure, and part of the drugs in the drug tank 10 are sucked into the system. Therefore, when the boiler equipment is operated again on Monday of the new week, the steam and condensed water become smelly. In addition, the amount of liquid medicine in the drug tank 10 was observed, and it was found that even if the boiler equipment was stopped, 13 liters of drugs were added to the system on Saturday and Sunday alone.

[0089] Although the present invention has been described in detail using specific embodiments, it is obvious to those skilled in the art that various modifications can be made within the scope of achieving the effects of the invention.

[0090] This application is based on Japanese Patent Application No. 2023-032905 filed on March 3, 2023, the entire contents of which are incorporated herein by reference.

[0091] Description of Reference Numerals

[0092] 1: Boiler.

[0093] 5: Heat exchanger.

[0094] 10: Medicine cans.

[0095] 11: Drug injection pump.

[0096] 13: Anti-siphon check valve.

[0097] 15: Pressure sensor.

[0098] 16: Controller.

[0099] 18: Steam trap.

[0100] 19: Steam circulation detection sensor.

[0101] 20, 25: Siphon.

[0102] 22: Pressure switch.

Claims

1. A method for injecting chemicals into a steam system, which is a method for injecting chemicals into a steam system by controlling the injection of water treatment chemicals into the steam system, wherein: The method of injecting chemicals into the steam system controls the injection of the water treatment chemicals using the chemical injection pump according to the following contents: A pressure sensor, a temperature sensor, or a steam trap provided in the steam system as a steam circulation detection mechanism; A chemical injection pump for injecting water treatment chemicals into the steam system; and The steam circulation detection status of the steam circulation detection mechanism.

2. The method for injecting medicine into a steam system according to claim 1, characterized in that: The steam circulation detection mechanism is a sensor composed of the pressure sensor or the temperature sensor. When the detection value of the sensor is above the threshold value, the drug injection pump is operated. When the detection value of the sensor is less than the threshold value, the drug injection pump is stopped.

3. The method of injecting medicine into a steam system according to claim 1, characterized in that: The steam circulation detection mechanism includes the steam trap and a steam circulation detection sensor of the steam trap. The chemical injection pump is operated when the steam circulation detection sensor detects the steam circulation, and is stopped when the steam circulation detection sensor does not detect the steam circulation.

4. The method of injecting medicine into a steam system according to claim 1, characterized in that: An anti-siphon check valve is provided in the chemical injection piping that guides the water treatment chemical from the chemical injection pump to the steam system.

5. The method of injecting medicine into a steam system according to claim 1, characterized in that: The installation position of the steam circulation detection mechanism in the steam system and the injection point of the water treatment chemical from the chemical injection pump into the steam system are located on the secondary side of the steam flow regulating valve installed in the steam system.

6. The method for injecting a drug into a steam system according to any one of claims 1 to 5, characterized in that: The water treatment chemical is sprayed by a spray nozzle at a point where the water treatment chemical is injected from the chemical injection pump into the steam system, and is injected into the steam system.

Images