Automatic control and adjustment device for crude oil pipeline additive and method of using same

Abstract

The present application relates to the technical field of petroleum geological exploration, and is an automatic control and adjusting device for adding agent to crude oil pipeline and a use method thereof, which comprises a controller, a plunger large pump, a plunger small pump, an agent tank and a crude oil pipeline. First, according to the compatibility test in the laboratory, the application experience data, the concentration of the added agent and the effective concentration ω of the agent provided by the manufacturer are set on the controller as needed. Then, the controller obtains the real-time data of the crude oil flowmeter on the crude oil pipeline online, and the injection amount Q of the chemical additive is calculated by using a formula. The injection amount Q of the chemical additive is input, the controller is automatically controlled and operated, and the intelligent injection of the agent into the crude oil pipeline is completed. The present application monitors the basic flow of the crude oil pipeline online through the controller, automatically controls the start and stop of the agent pump and the amount of the added agent according to the internal calculation of the controller based on the set concentration, improves the precision of the added agent, and reduces the labor intensity of the staff and the safety risk in the operation process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil geological exploration, and is an automatic control and adjusting device for adding agents to crude oil pipelines and a use method thereof. BACKGROUND

[0002] Pipeline chemical additive technology is a method of changing the flow characteristics of the conveying medium by injecting chemical synthetic reagents into the pipeline, which can reduce the minimum conveying requirement of the pipeline, improve the safety operation margin of the low-conveying pipeline, or reduce resistance and increase conveying.

[0003] Chemicals that can significantly improve certain properties of crude oil products are mostly artificially synthesized organic compounds that can be dissolved in mineral oil. After various refining processes, the various products processed from crude oil often cannot directly meet the requirements of various mechanical equipment for the use performance of oil products. An effective and relatively economical method is to add various additives, and the addition amount is generally several thousandths to several percent.

[0004] Pour point depressants are chemicals that can lower the freezing point of crude oil, improve the flowability of crude oil, reduce the minimum conveying requirement of the pipeline, and improve the safety operation margin of the low-conveying pipeline. Pour point depressants are mainly applied to waxy crude oil pipelines, and the purpose is to reduce the freezing point, viscosity, yield value, and wax deposition strength of crude oil, improve the low-temperature flowability, and provide guarantee for the safe operation, shutdown and restart, and normal-temperature conveying of low-conveying pipelines.

[0005] Resistance reducers include oil resistance reducers and natural gas resistance reducers, which can be applied to crude oil, refined oil, and natural gas pipelines, and the purpose is to reduce the frictional resistance loss along the pipeline, save energy and reduce consumption, and improve the "elasticity" of pipeline conveying and the pipeline flow capacity or reduce the energy consumption of pipeline conveying.

[0006] Other pipeline chemical additives also have viscosity reducer, wax inhibitor, corrosion inhibitor, natural gas hydrate inhibitor, multifunctional pipe wall coating, oil spill recovery agent, gel spacer, etc. At present, the dosage of the above-mentioned chemical additives is adjusted by manual calculation and manual adjustment. The adjustment process is as follows: the staff first collects the basic flow of the pipeline in the previous hour, manually calculates the dosage according to the dosage concentration requirement, and adjusts the dosage at the dosage equipment site. It takes about 30 minutes to adjust to the right each time. When the basic flow changes or the concentration needs to be adjusted, the staff needs to collect data, calculate and adjust frequently for several hours to achieve a reasonable and stable concentration requirement. Therefore, there are the following problems: 1) unable to obtain the flow data of the pipeline in real time, and adjust the dosage in time, resulting in uneven concentration of the additive in the pipeline, inconsistent additive effect, and in severe cases, blank samples directly into the pipeline, directly threatening safe operation; 2) the adjustment time is generally between 30 minutes and 5 hours, especially for pipelines with drag reducing agent, as the drag reducing agent is added, the effective pipe section increases, the additive effect appears, and the drag reducing agent needs to be adjusted multiple times during the dynamic effect process. The labor intensity of the staff is large, and there are safety risks in the process of operation.

[0007] The patent document with the publication number CN206476738U discloses a kind of injection device of crude oil drag reducing agent, mainly including discharge mechanism and feed mechanism, discharge mechanism includes support and feeding tank, the bottom end of feeding tank is fixedly connected with discharge pipe, is connected gear pump and two discharge ports, discharge port is fixedly connected with the same and parallelly arranged feed mechanism, feed mechanism includes feed pipeline, and is sequentially connected with liquid inlet ball valve, metering pump, control valve.But the device structure is relatively simple, the adjustable range is small, and automatic adjustment function cannot be realized according to the dosage concentration requirement. SUMMARY

[0008] The present application provides a kind of crude oil pipeline additive automatic control adjusting device and its use method, overcome the deficiency of above-mentioned prior art, it can effectively solve the problems of too much human intervention, single dosage adjustable range, large labor intensity of staff and high operation safety risk when existing crude oil pipeline chemical additive is injected.

[0009] One of the technical solutions of the present application is realized by the following measures: an automatic control adjusting device for adding agent to crude oil pipeline, comprising a controller, a plunger large pump, a plunger small pump, an agent tank and a crude oil pipeline, a first agent adding pipeline is fixedly communicated between the outlet of the agent tank and the crude oil pipeline, the plunger large pump is fixedly installed on the first agent adding pipeline, first parallel pipelines are parallelly arranged on the first agent adding pipeline before and after the plunger large pump, a large pump outlet bypass valve is fixedly installed on the first parallel pipeline, a second agent adding pipeline is fixedly communicated between the first agent adding pipeline between the agent tank and the plunger large pump and the first agent adding pipeline between the plunger large pump and the crude oil pipeline, the plunger small pump is fixedly installed on the second agent adding pipeline, second parallel pipelines are parallelly arranged on the second agent adding pipeline before and after the plunger small pump, a small pump outlet bypass valve is fixedly installed on the second parallel pipeline, a crude oil flowmeter is fixedly installed on the crude oil pipeline between the crude oil pipeline inlet and the first agent adding pipeline, and the plunger large pump, the plunger small pump, the large pump outlet bypass valve, the small pump outlet bypass valve and the crude oil flowmeter are electrically connected with the controller.

[0010] The following is a further optimization or / and improvement of one of the above technical solutions of the present application:

[0011] A first ball valve is fixedly installed on the first agent adding pipeline between the second agent adding pipeline and the agent tank, a circulating pipeline is fixedly communicated between the first agent adding pipeline between the first ball valve and the agent tank and the first agent adding pipeline between the second agent adding pipeline and the first ball valve, and a circulating pump is fixedly installed on the circulating pipeline.

[0012] An agent return tank pipeline is fixedly communicated on the first agent adding pipeline between the circulating pipeline outlet and the first ball valve.

[0013] A first safety valve is arranged between the first agent adding pipeline between the first parallel pipeline inlet and the second agent adding pipeline inlet and the first agent adding pipeline between the first parallel pipeline outlet and the second agent adding pipeline outlet, and a second safety valve is arranged between the second agent adding pipeline between the second parallel pipeline inlet and the first agent adding pipeline inlet and the second agent adding pipeline between the second parallel pipeline outlet and the first agent adding pipeline outlet.

[0014] A remote pressure gauge is arranged on the first agent adding pipeline between the second agent adding pipeline and the circulating pipeline, and the first safety valve, the second safety valve, the remote pressure gauge and the circulating pump are electrically connected with the controller.

[0015] A guide is arranged on the first agent adding pipeline between the first safety valve and the second agent adding pipeline and on the second agent adding pipeline between the second safety valve and the first agent adding pipeline.

[0016] A second ball valve is fixedly installed on the first agent adding pipeline between the first safety valve and the second agent adding pipeline inlet, a third ball valve is fixedly installed on the second agent adding pipeline between the second safety valve and the first agent adding pipeline inlet, and a fourth ball valve is fixedly installed on the agent return tank pipeline.

[0017] The second technical solution of the present invention is achieved by the following measures: a method for using a crude oil pipeline dosing automatic control and adjustment device, comprising:

[0018] The first step is to set the dosage concentration and the effective concentration of the agent provided by the manufacturer on the controller as needed based on laboratory compatibility tests and field application experience data. 剂 ;

[0019] In the second step, the controller obtains the real-time data of the crude oil flow meter on the crude oil pipeline online and calculates the injection amount of chemical additives Q using the formula 剂 , with the filling amount of chemical additives Q 剂 As input, the controller controls the start and stop of the large plunger pump and the small plunger pump, as well as the valve opening of the large pump outlet bypass valve and the small pump outlet bypass valve, to complete the intelligent filling of crude oil pipeline additives.

[0020] The following is a further optimization and / or improvement of the second technical solution of the above invention:

[0021] In the second step above, the amount of chemical additives added is Q 剂 The calculation formula is as follows:

[0022]

[0023] In the formula, Q 剂 is the injection volume of chemical additives, L / h; C is the injection concentration required for safe operation of the pipeline, determined based on laboratory compatibility tests and field application experience data, ppm; Q 原油 is the real-time basic flow rate of the pipeline, t / h; ρ 原油 is the density of crude oil transported in pipeline at the dosing point, kg / m3; ω 剂 is the effective concentration of chemical additives, provided by the chemical additive manufacturer, %.

[0024] The present invention monitors the basic flow of the crude oil pipeline online through a controller. The controller automatically controls the start and stop of the dosing pump and the dosing amount according to the set concentration calculation, thereby improving the dosing accuracy and reducing the labor intensity of employees and the safety risks during operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Attachment Figure 1 This is a schematic diagram of the process flow of Example 1 of the present invention.

[0026] Attachment Figure 2 This is a schematic block diagram of the control logic for intelligently adding chemical additives to the controller of the present invention.

[0027] The codes in the accompanying drawings are: 1 is the controller, 2 is the large plunger pump, 3 is the small plunger pump, 4 is the chemical tank, 5 is the crude oil pipeline, 6 is the first dosing pipeline, 7 is the first parallel pipeline, 8 is the large pump outlet bypass valve, 9 is the second dosing pipeline, 10 is the second parallel pipeline, 11 is the small pump outlet bypass valve, 12 is the crude oil flow meter, 13 is the second ball valve, 14 is the circulation pipeline, 15 is the circulation pump, 16 is the chemical return tank pipeline, 17 is the first safety valve, 18 is the second safety valve, 19 is the remote pressure gauge, 20 is the guide, 21 is the third ball valve, 22 is the first ball valve, and 23 is the fourth ball valve. DETAILED DESCRIPTION

[0028] The present invention is not limited to the following embodiments, and specific implementation methods can be determined based on the technical solutions of the present invention and actual conditions.

[0029] The present invention will be further described below in conjunction with the embodiments:

[0030] Example 1: As shown in the attached Figure 1 As shown, the crude oil pipeline dosing automatic control and adjustment device includes a controller 1, a large plunger pump 2, a small plunger pump 3, a chemical tank 4 and a crude oil pipeline 5. A first chemical dosing pipeline 6 is fixedly connected between the outlet of the chemical tank 4 and the crude oil pipeline 5. The large plunger pump 2 is fixedly installed on the first chemical dosing pipeline 6. A first parallel pipeline 7 is connected in parallel to the first chemical dosing pipeline 6 before and after the large plunger pump 2. A large pump outlet bypass valve 8 is fixedly installed on the first parallel pipeline 7. The first chemical dosing pipeline 6 between the chemical tank 4 and the large plunger pump 2 and the first chemical dosing pipeline 6 between the large plunger pump 2 and the crude oil pipeline 5 are connected in parallel. A second dosing pipeline 9 is fixedly connected between the first dosing pipeline 6 and the second dosing pipeline 9, a small plunger pump 3 is fixedly installed on the second dosing pipeline 9, a second parallel pipeline 10 is connected in parallel to the second dosing pipeline 9 before and after the small plunger pump 3, a small pump outlet bypass valve 11 is fixedly installed on the second parallel pipeline 10, a crude oil flowmeter 12 is fixedly installed on the crude oil pipeline 5 between the inlet of the crude oil pipeline 5 and the first dosing pipeline 6, and the large plunger pump 2, the small plunger pump 3, the large pump outlet bypass valve 8, the small pump outlet bypass valve 11 and the crude oil flowmeter 12 are all electrically connected to the controller 1.

[0031] According to the different dosage requirements of the drag reducer and the pour point depressant, the controller 1 can realize three modes: starting the small plunger pump 3 alone, starting the large plunger pump 2 alone, and starting the large plunger pump 2 and the small plunger pump 3 in parallel. This greatly increases the range of crude oil pipeline dosing, improves the overall adaptability of the device, reduces maintenance workload, and thus realizes precise and intelligent filling of chemical additives in the crude oil pipeline 5.

[0032] Example 2: As an optimization of the above embodiment, as shown in the attached Figure 1As shown, the first ball valve 22 is fixedly installed on the first medicament feeding pipeline 6 between the second medicament feeding pipeline 9 and the medicament tank 4, the circulation pipeline 14 is fixedly communicated between the first medicament feeding pipeline 6 between the first ball valve 22 and the medicament tank 4 and the first medicament feeding pipeline 6 between the second medicament feeding pipeline 9 and the first ball valve 22, and the circulation pump 15 is fixedly installed on the circulation pipeline 14.

[0033] Embodiment 3: As an optimization of the above-mentioned embodiments, as shown in the accompanying Figure 1 As shown, the medicament return tank pipeline 16 is fixedly communicated on the first medicament feeding pipeline 6 between the outlet of the circulation pipeline 14 and the first ball valve 22.

[0034] Embodiment 4: As an optimization of the above-mentioned embodiments, as shown in the accompanying Figure 1 As shown, the first safety valve 17 is arranged between the first medicament feeding pipeline 6 between the inlet of the first parallel pipeline 7 and the inlet of the second medicament feeding pipeline 9 and the first medicament feeding pipeline 6 between the outlet of the first parallel pipeline 7 and the outlet of the second medicament feeding pipeline 9, and the second safety valve 18 is arranged between the second medicament feeding pipeline 9 between the inlet of the second parallel pipeline 10 and the inlet of the first medicament feeding pipeline 6 and the second medicament feeding pipeline 9 between the outlet of the second parallel pipeline 10 and the outlet of the first medicament feeding pipeline 6.

[0035] Embodiment 5: As an optimization of the above-mentioned embodiments, as shown in the accompanying Figure 1 As shown, the remote pressure gauge 19 is arranged on the first medicament feeding pipeline 6 between the second medicament feeding pipeline 9 and the circulation pipeline 14, and the first safety valve 17, the second safety valve 18, the remote pressure gauge 19 and the circulation pump 15 are electrically connected with the controller 1.

[0036] According to needs, when the remote pressure gauge 19 shows that the pressure is too high, the first safety valve 17 or the second safety valve 18 can be opened by the controller 1 to release pressure, so as to prevent the pressure in the pipeline from being blocked.

[0037] Embodiment 6: As an optimization of the above-mentioned embodiments, as shown in the accompanying Figure 1 As shown, the guide 20 is arranged on the first medicament feeding pipeline 6 between the first safety valve 17 and the second medicament feeding pipeline 9 and on the second medicament feeding pipeline 9 between the second safety valve 18 and the first medicament feeding pipeline 6.

[0038] Embodiment 7: As an optimization of the above-mentioned embodiments, as shown in the accompanying Figure 1 As shown, the second ball valve 13 is fixedly installed on the first medicament feeding pipeline 6 between the first safety valve 17 and the inlet of the second medicament feeding pipeline 9, the third ball valve 21 is fixedly installed on the second medicament feeding pipeline 9 between the second safety valve 18 and the inlet of the first medicament feeding pipeline 6, and the fourth ball valve 23 is fixedly installed on the medicament return tank pipeline 16.

[0039] According to the need, when the production is abnormal or the medicament needs to be emptied, the controller 1 starts the circulating pump 15 after the first ball valve 22, the second ball valve 13, the third ball valve 21 are closed and the fourth ball valve 23 is opened, so that the medicament can be emptied.

[0040] In the present application, the devices and apparatus used are all the devices and apparatus commonly known in the art, unless otherwise specified.

[0041] According to the need, the pipelines and devices of the crude oil pipeline medicament automatic control and adjustment device can also be provided with conventional valves, thermometers and pressure gauges commonly known in the art according to the production needs, and the pipelines can also be provided with quick short circuits according to the need, and the short circuits are all in the buckle type quick installation mode, which is convenient for unblocking after the medicament device is disabled.

[0042] Embodiment 8: as shown in the accompanying Figure 1 The use method of the crude oil pipeline medicament automatic control and adjustment device comprises the following steps:

[0043] First step, according to the laboratory compatibility test, the field application experience data, set the medicament concentration, the effective concentration ω 剂 of the medicament provided by the manufacturer on the controller 1 according to the need.

[0044] Second step, the controller 1 obtains the real-time data of the crude oil flowmeter 12 on the crude oil pipeline 5 online, and calculates the filling amount Q 剂 of the chemical additive by using the formula, and takes the filling amount Q 剂 of the chemical additive as the input, and the controller 1 controls the start and stop of the plunger large pump 2 and the plunger small pump 3 and the valve opening degree of the large pump outlet bypass valve 8 and the small pump outlet bypass valve 11, to complete the intelligent filling of the crude oil pipeline medicament.

[0045] According to the need, the controller 1 in the present application can be an ARM720T microprocessor.

[0046] The specific control logic process of the controller 1 for intelligent filling of the chemical additive in the present application is as follows (as shown in the accompanying Figure 2 ):

[0047] When the output of the controller 1 is less than A_POINT, the small pump outlet bypass valve 11 (small flow regulating valve) is opened, the plunger small pump 3 (small pump) is started, the plunger large pump 2 (large pump) is stopped, and the large pump outlet bypass valve 8 (large flow regulating valve) is closed;

[0048] When the output of the controller 1 is greater than A_POINT, the large pump outlet bypass valve 8 (large flow regulating valve) is opened, the plunger large pump 2 (large pump) is started, the plunger small pump 3 (small pump) is stopped, and the small pump outlet bypass valve 11 (small flow regulating valve) is closed.

[0049] Example 9: As the optimization of the above-mentioned examples, in the second step, the injection amount Q of the chemical additive 剂 The calculation formula is as follows:

[0050]

[0051] In the formula, Q 剂 is the injection amount of the chemical additive, L / h; C is the injection concentration required for safe operation of the pipeline, which is determined according to laboratory compatibility test and field application experience data, ppm; Q 原油 is the real-time basic flow of the pipeline, t / h; p 原油 is the density of the pipeline crude oil at the addition point, kg / m3; w 剂 is the effective concentration of the chemical additive, %, which is generally provided by the chemical additive manufacturer.

[0052] Example 10: Injection of drag reduction agent

[0053] The original agent pry pump is two 100L / H plunger pumps, which can only meet the 20L / H to 100L / H agent metering range. The possible high flow pipelines of the company in the past five years are calculated at the existing basic flow and the flow after the action of the drag reduction agent (30% increase rate), respectively, at two commonly used agent concentrations (15ppm, 30ppm). The agent demand of the blank sample and the agent sample is shown in Table 1, wherein the effective concentration of the drag reduction agent is 100%.

[0054] As can be seen from Table 1, the basic flow of the seven high flow pipelines is between 100t / h and 625t / h, and the drag reduction agent injection amount is between 1.8L / H and 22.1L / H. After the action of the drag reduction agent (estimated according to the increase rate of 30%), the pipeline flow will increase to 130t / h to 812t / h, and the agent amount will increase to 2.3L / H to 28.7L / H. Therefore, the range of the drag reduction agent injection pump is required to be 1.8L / H to 28.7L / H, which has the characteristics of small overall agent amount and large range, and the existing agent pry process does not have the injection condition, and a small-dose and large-range drag reduction agent injection process needs to be designed. In the automatic control and adjustment device for crude oil pipeline agent of the application, by setting the displacement of the plunger small pump 3 to 8L / H and the displacement of the plunger large pump 2 to 30L / H on the controller 1, the parallel operation mode of the plunger large pump 2 and the plunger small pump 3 is started, which can meet the automatic injection amount of the drag reduction agent.

[0055] In summary, the application can monitor the basic flow of the crude oil pipeline 5 online through the controller, automatically control the start and stop of the agent pump and the agent amount according to the internal calculation of the set concentration controller 1, improve the agent precision, and reduce the labor intensity and safety risk of the staff in the operation process.

[0056] The above technical features constitute embodiments of the present application, which have strong adaptability and implementation effects. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

[0057] Table 1

[0058]

Claims

1. A method of using an automatic control regulator for an additive injection system for a crude oil pipeline, the method comprising: The application relates to an automatic control and adjustment device for crude oil pipeline additive. The first step is to set the additive concentration and the effective additive concentration omega on the controller according to the laboratory compatibility test and the field application experience data; The second step is to obtain the real-time data of a crude oil flowmeter on a crude oil pipeline by the controller, to calculate the additive injection amount Q of the chemical additive by a formula, to take the additive injection amount Q of the chemical additive as the input, to control the start and stop of the plunger big pump and the plunger small pump and the valve opening degree of the big pump outlet bypass valve and the small pump outlet bypass valve, and to complete the intelligent injection of the crude oil pipeline additive, The automatic control and adjustment device for the crude oil pipeline additive comprises a controller, a plunger big pump, a plunger small pump, a chemical agent tank and a crude oil pipeline, a first additive pipeline is fixedly communicated between the outlet of the chemical agent tank and the crude oil pipeline, the plunger big pump is fixedly installed on the first additive pipeline, first parallel pipelines are parallelly arranged on the first additive pipeline before and after the plunger big pump, a big pump outlet bypass valve is fixedly installed on the first parallel pipeline, a second additive pipeline is fixedly communicated between the first additive pipeline between the chemical agent tank and the plunger big pump and the first additive pipeline between the plunger big pump and the crude oil pipeline, a plunger small pump is fixedly installed on the second additive pipeline, second parallel pipelines are parallelly arranged on the second additive pipeline before and after the plunger small pump, a small pump outlet bypass valve is fixedly installed on the second parallel pipeline, a crude oil flowmeter is fixedly installed on the crude oil pipeline between the crude oil pipeline inlet and the first additive pipeline, and the plunger big pump, the plunger small pump, the big pump outlet bypass valve, the small pump outlet bypass valve and the crude oil flowmeter are electrically connected with the controller.

2. The method of using the automatic control regulator for crude oil pipeline additive according to claim 1, characterized in that A first ball valve is fixedly installed on the first additive pipeline between the second additive pipeline and the chemical agent tank, a circulating pipeline is fixedly communicated between the first additive pipeline between the first ball valve and the chemical agent tank and the first additive pipeline between the second additive pipeline and the first ball valve, and a circulating pump is fixedly installed on the circulating pipeline.

3. The method of using the automatic control regulator for crude oil pipeline additive according to claim 2, characterized in that A chemical agent return tank pipeline is fixedly communicated on the first additive pipeline between the circulating pipeline outlet and the first ball valve.

4. The method of using the automatic control regulator for crude oil pipeline additive according to claim 1 or 2 or 3, characterized in that First safety valves are arranged between the first additive pipeline between the first parallel pipeline inlet and the second additive pipeline inlet and the first additive pipeline between the first parallel pipeline outlet and the second additive pipeline outlet, and second safety valves are arranged between the second additive pipeline between the second parallel pipeline inlet and the first additive pipeline inlet and the second additive pipeline between the second parallel pipeline outlet and the first additive pipeline outlet.

5. The method of using the automatic control regulator for crude oil pipeline additive according to claim 4, characterized in that Remote pressure gauges are arranged on the first additive pipeline between the second additive pipeline and the circulating pipeline, the first safety valves, the second safety valves, the remote pressure gauges and the circulating pump are electrically connected with the controller.

6. The method of using the automatic control regulator for crude oil pipeline additive according to claim 5, characterized in that Guides are arranged on the first additive pipeline between the first safety valve and the second additive pipeline and on the second additive pipeline between the second safety valve and the first additive pipeline.

7. The method of using the automatic control regulator for crude oil pipeline additive according to claim 5 or 6, characterized in that Second ball valves are fixedly installed on the first additive pipeline between the first safety valve and the second additive pipeline inlet, third ball valves are fixedly installed on the second additive pipeline between the second safety valve and the first additive pipeline inlet, and fourth ball valves are fixedly installed on the chemical agent return tank pipeline.

8. The method of using the automatic control regulator for crude oil pipeline additive according to claim 7, characterized in that In the second step, the amount Q of chemical additive to be added 剂 The calculation formula is as follows: In the formula, Q 剂 is the filling amount of the chemical additive, L / h; C is the filling concentration required for safe operation of the pipeline, ppm; Q 原油 is the real-time basic flow of the pipeline, t / h; p 原油 is the density of the crude oil at the additive point, kg / m³; w 剂 is the effective concentration of the chemical additive, %.

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