Method for controlling pH value of blast furnace gas pipeline condensate water
By setting up multiple alkali injection points on the blast furnace gas pipeline and using pH meters and temperature sensors to control the alkali flow rate, the problem of condensate corrosion in the blast furnace gas pipeline was solved, achieving low-cost and effective full-process corrosion protection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIANGSU SHAGANG STEEL CO LTD
- Filing Date
- 2026-04-02
- Publication Date
- 2026-05-12
AI Technical Summary
In the existing technology, after HCl is precipitated from the condensate in the blast furnace gas pipeline, the single-point injection of alkaline solution still poses a risk of corrosion to pipelines far from the injection point. In addition, there are problems such as high construction costs, large land occupation, high operating costs, large pipeline network resistance, and pipeline blockage.
Multiple alkali injection points are set up on the blast furnace gas pipeline. The condensate generation point is detected and alkali is injected from the previous point to neutralize the HCl in the condensate. The flow rate of alkali is controlled by pH meter and temperature sensor to avoid alkali waste and solute precipitation. Insulation components are installed to reduce condensate precipitation.
Effectively control the pH value of blast furnace gas pipelines to prevent corrosion, reduce construction and operation costs, avoid pipeline blockage, and achieve full-process corrosion protection.
Smart Images
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Abstract
Description
Technical Field
[0001] This application relates to the field of steelmaking by-product treatment technology, and in particular to a method for controlling the pH value of condensate in blast furnace gas pipelines. Background Technology
[0002] Blast furnace gas contains HCl gas. During gas pipeline transportation, as the temperature decreases, the HCl condenses and precipitates along with moisture in the gas. The HCl-containing condensate is highly acidic; without neutralization, its pH value can drop below 1.0, making it highly corrosive to gas pipelines. Therefore, to reduce corrosion in blast furnace gas pipelines, many companies have installed alkali injection systems, primarily to neutralize the HCl in the condensate and raise the pH value.
[0003] In existing technologies, alkali injection processes are mainly divided into two types: one involves constructing a separate alkali injection tower, and the other involves directly injecting alkali solution at a specific point in the blast furnace gas pipeline. For the first type, the main problems are high construction costs, large land area required, high operating costs, and significant pipeline network resistance. Furthermore, as the pipeline distance from the injection tower increases, acidic gases and condensate continue to be released, and the pH value of the condensate gradually decreases, posing a continued risk of corrosion. For the second type, the main problem is that due to sedimentation, the injected alkali solution often only neutralizes a short area close to the injection point. The neutralization effect tends to worsen with increasing distance. Additionally, when excessive alkali solution is injected, the settled alkali solute can easily cause pipeline blockage and exacerbate corrosion.
[0004] Both methods used single-point injection of alkali solution, which caused the pH value to decrease again as the distance between the gas pipeline and the injection point increased, exacerbating corrosion. Summary of the Invention
[0005] The purpose of this application is to provide a method for controlling the pH value of condensate in blast furnace gas pipelines. By setting several points on the pipeline where alkaline solution can be sprayed, and starting the spraying of alkaline solution before condensate appears, the method solves the problem that in the prior art, when alkaline solution is sprayed at a single point, pipelines far from the spraying points are still at risk of corrosion.
[0006] To achieve one of the above-mentioned objectives, one embodiment of this application provides a method for controlling the pH value of condensate in blast furnace gas pipelines, comprising the following steps:
[0007] Several alkali injection points are set along the blast furnace gas pipeline, and alkali injection points are equipped with alkali injectors. Check if condensation is generated at each point. Turn on the alkaline spray nozzles at the points before the first point that generates condensation to the points before the last point that generates condensation, in order to neutralize the HCl dissolved in the condensation between the first and last points that generate condensation.
[0008] In one embodiment of this application, the alkaline solution injection flow rate is: , Among them, V An The required flow rate of alkali at the nth point, in kg / h; a = 1 or 2; c is the mass concentration of the alkali solution; V n+1 It is the flow rate of condensate produced from point n to point n+1, in kg / h; c HCl It's the acid concentration. is the target acid concentration, both in mol / kg; M is the relative molecular mass of the base, in g / mol.
[0009] In one embodiment of this application,
[0010] Among them, T n T is the gas temperature at the nth point. n+1 V represents the gas temperature at the (n+1)th point, in °C; e is the natural logarithm; g This is the blast furnace gas flow rate, measured in meters per second (m³). 3 / h.
[0011] In one embodiment of this application, a pH meter is provided at the first point where condensate is generated to measure the pH value of the condensate.
[0012] In one embodiment of this application, , = pH is the pH value of the first point where condensate is generated, and pH0 is the target pH value.
[0013] In one embodiment of this application, the alkaline sprayer installed at the point preceding the first point where condensate is generated gradually increases the alkaline spray flow rate until the pH value of the first point where condensate is generated reaches the target pH value.
[0014] In one embodiment of this application, a temperature sensor is provided at each alkali injection point to detect the gas temperature at that point.
[0015] In one embodiment of this application, a condensate drain device is provided at each alkaline spray point.
[0016] In one embodiment of this application, the distance between adjacent alkali injection points tends to increase in the direction of blast furnace gas flow.
[0017] In one embodiment of this application, an insulation component is provided outside the blast furnace gas pipeline to reduce the amount of condensate.
[0018] One or more technical solutions provided in this application have at least the following technical effects or advantages: The method for controlling the pH value of condensate in blast furnace gas pipelines provided in this application involves setting multiple points on the blast furnace gas pipeline, with an alkaline injector at each point capable of injecting alkaline solution. Alkaline solution is injected at the point before condensate begins to appear, preventing acid corrosion of the pipeline before the point where condensate appears. Alkaline solution injection is stopped at the last point where condensate appears, avoiding waste of alkaline solution and solute sedimentation that could lead to pipeline blockage and increased corrosion. Detailed Implementation
[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] This application provides a method for controlling the pH value of condensate in blast furnace gas pipelines, including the following steps: Several alkali injection points are set along the blast furnace gas pipeline, and alkali injection points are equipped with alkali injectors. Check if condensation is generated at each point. Turn on the alkaline spray nozzles at the points before the first point that generates condensation to the points before the last point that generates condensation, in order to neutralize the HCl dissolved in the condensation between the first and last points that generate condensation.
[0021] For the first point where condensation occurs (let's say it's the p-th point), since the condensation is produced in the pipe between the p-1-th point and the p-th point, it is necessary to spray alkaline solution at the p-1-th point (the point before the first point where condensation occurs) to prevent corrosion.
[0022] For the last point where condensate is generated (let's say it's the qth point), that is, the q+1th point has no condensate discharge, it means that the gas temperature has become relatively stable and changes little from the qth point onwards. There is no condensate or only a small amount of condensate precipitation afterward, which has little impact on pipeline corrosion. Therefore, there is no need to spray alkaline solution at the qth point and subsequent points.
[0023] In this application, multiple points are set on the blast furnace gas pipeline, and each point is equipped with an alkaline injector capable of injecting alkaline solution. The alkaline solution is injected at the point before condensation begins to appear, in order to prevent the pipeline before the point where condensation occurs from being corroded by acid. The alkaline solution injection is stopped at the last point where condensation occurs, to avoid waste of alkaline solution and solute sedimentation that could lead to pipeline blockage and aggravated corrosion.
[0024] The method described in this application can control the pH value of the entire blast furnace gas pipeline under low-cost conditions to prevent pipeline corrosion.
[0025] In some embodiments of this application, the alkaline solution injection flow rate is: Equation (1) Among them, V An The required flow rate of alkali at the nth point, in kg / h; a = 1 or 2; c is the mass concentration of the alkali solution; V n+1 It is the flow rate of condensate produced from point n to point n+1, in kg / h; c HCl It's the acid concentration. is the target acid concentration, both in mol / kg; M is the relative molecular mass of the base, in g / mol.
[0026] The alkali solution sprayed by the alkali injector will flow with the blast furnace gas under the influence of the blast furnace gas. That is, the alkali solution sprayed by the alkali injector at the nth point is used to neutralize the acid dissolved in the condensate generated from the nth point to the (n+1)th point. This application assumes that the acid dissolved in the condensate is only HCl.
[0027] The difference between the HCl concentration and the target HCl concentration represents the decrease in HCl concentration after the alkaline solution is injected. The required decrease in HCl concentration is related to the flow rate V of the condensate generated between point n and point (n+1). n+1 The product of these two values represents the amount of HCl that needs to be reduced. Multiplying this by the relative molecular mass of the alkali used and then dividing by the mass concentration of the alkali solution gives the required flow rate of alkali.
[0028] Because one HCl molecule provides one H... + The base used may have one molecule that can provide an OH group. - (e.g., NaOH), some bases can provide two OH groups per molecule. - (e.g., Ca(OH)2), when the base used provides one OH group for one molecule. - When the acid-base reaction ratio is 1:1, then a is 1; when the base used provides two OH groups for one molecule... - When the reaction ratio of acid to base is 2:1, then a is 2.
[0029] In some embodiments of this application, Equation (2) Among them, T n T is the gas temperature at the nth point. n+1 V represents the gas temperature at the (n+1)th point, in °C; e is the natural logarithm; g This is the blast furnace gas flow rate, measured in meters per second (m³). 3 / h.
[0030] The moisture content of saturated blast furnace gas is similar to that of saturated air, mainly related to temperature. The inventors' research revealed the following relationship between the moisture content of saturated air and air temperature: , where m 水 This refers to the water content in saturated air, expressed in g / m³. 3 T represents the air temperature in °C; e represents the natural logarithm, typically 2.71828.
[0031] After the first point where condensate appears, the water vapor content in the gas has reached saturation. Therefore, as the transportation distance increases and the gas temperature decreases further, condensate will continue to appear at subsequent points. Using the aforementioned formula for air saturation water content, the flow rate of condensate between different points can be calculated, i.e., the aforementioned formula (2). According to formula (2), the flow rate of condensate generated between the nth point and the (n+1)th point can be calculated.
[0032] In some embodiments of this application, a pH meter is provided at the first point where condensate is generated to measure the pH value of the condensate.
[0033] The more condensate is produced, the more HCl is dissolved in the condensate, but the two increase in a basically linear manner. That is, if the acid concentration in the blast furnace gas pipeline is basically the same, the pH value will also be the same. Therefore, only one pH meter needs to be installed on the blast furnace gas pipeline, which can save unnecessary instruments.
[0034] In some embodiments of this application, , = pH is the pH value of the first point where condensate is generated, and pH0 is the target pH value.
[0035] By directly measuring the acidity or alkalinity of condensate with a pH meter and calculating the HCl concentration based on the pH value, the pH meter can be used effectively.
[0036] In some embodiments of this application, the alkaline sprayer installed at the point preceding the first point where condensate is generated gradually increases the alkaline spray flow rate until the pH value of the first point where condensate is generated reaches the target pH value.
[0037] Before the first point where condensate forms, it's impossible to determine the temperature at which the blast furnace gas reaches saturation, making calculations using the above formula impossible. Instead, the alkali solution must be added directly based on the pH value. From the first point where condensate forms onwards, the blast furnace gas can be confirmed to be saturated. Precise calculations using the above formula can then be performed to control the alkali injection flow rate and maintain the pH value within the blast furnace gas pipeline at the target level.
[0038] Setting up a pH meter at the first point where condensation occurs not only satisfies the pH value required for calculating the HCl concentration, but also allows for real-time monitoring of the pH value at the first point where condensation occurs, thereby controlling the alkali spray flow rate at the point preceding the first point where condensation occurs.
[0039] In some embodiments of this application, a temperature sensor is provided at each alkali injection point to detect the gas temperature at that point.
[0040] In some embodiments of this application, each alkali injection point is equipped with a condensate drain device, so that the condensate generated during the transportation of blast furnace gas in the pipeline can be discharged in a timely manner, thereby reducing the pressure of the blast furnace gas pipeline.
[0041] In some embodiments of this application, the distance between adjacent alkali injection points tends to increase in the direction of blast furnace gas flow.
[0042] Among the points where condensation occurs, the closer to the starting point of the blast furnace gas, the greater the temperature drop at the same distance, and thus the more condensation is produced. In the direction of blast furnace gas flow (i.e., away from the starting point), the distance between adjacent points is gradually increased. That is, the distance between points near the starting point is smaller, resulting in less condensation between adjacent points, thereby reducing the pressure for condensation discharge. Conversely, the distance between points farther from the starting point is larger, thus controlling the drainage volume at any given point to be relatively consistent.
[0043] In some embodiments of this application, the blast furnace gas pipeline is provided with insulation to reduce the amount of condensate.
[0044] The technical solution of this application will be further described below with reference to some specific embodiments.
[0045] Example 1 Six points equipped with alkali injectors, temperature sensors, and condensate drainage devices were set along the blast furnace gas pipeline. The gas temperature and presence of condensate at the six points are shown in the table below.
[0046]
[0047] Condensate was discharged from point #2, and its pH value was measured to be 1.5. Alkali spraying is required at point #1. Gradually increase the flow rate of alkali solution at point #1 until the pH value of the condensate at point #2 reaches the target value of pH0=5.0.
[0048] Since condensate is also discharged from points 3#, 4#, and 5#, in addition to point 1#, points 2#, 3#, and 4# also need to be sprayed with alkaline solution.
[0049] The gas flow rate is V g =270100m 3 / h, according to formula (2), the flow rates of condensate precipitated at points 3#, 4# and 5# are V3=3903.3kg / h, V4=1238.3kg / h and V5=711.8kg / h respectively.
[0050] The alkaline solution used is a 5% NaOH solution with a molecular weight of 40 g / mol. The amount of alkaline solution required for points 2#, 3#, and 4# is calculated according to formula (1) as V. A2 =98.71kg / h, V A3 =31.32kg / h, V A4 =18.00kg / h.
[0051] The absence of condensate discharge at point 6 indicates that the gas temperature has stabilized from this point onwards, with little or no condensate discharge expected, which has minimal impact on pipeline corrosion. Therefore, neither point 5 nor point 6 requires alkali spraying.
[0052] Example 2 Six points equipped with alkali injectors, temperature sensors, and condensate drainage devices were set along the blast furnace gas pipeline. The gas temperature and presence of condensate at the six points are shown in the table below.
[0053]
[0054] Condensate was discharged from point 3, and its pH value was measured to be 1.9. Alkali spraying is required at point 2. Gradually increase the flow rate of alkali solution at point 2 until the pH value of the condensate at point 3 reaches the target value of pH0=5.5.
[0055] Since condensate is also discharged from point 4, in addition to point 2, point 3 also needs to be sprayed with alkaline solution.
[0056] The gas flow rate is V g =215000m 3 / h, according to formula (2), the flow rate of condensate precipitated at point 4 is V4=4137.65kg / h.
[0057] The alkaline solution used is a 5% NaOH solution with a molecular weight of 40 g / mol. The amount of alkaline solution required at point #3 is calculated as V according to formula (1). A3 =49.92kg / h.
[0058] The absence of condensate discharge at point 5 indicates that the gas temperature has stabilized from this point onwards, with little or no condensate discharge expected, which has minimal impact on pipeline corrosion. Therefore, no alkali spraying is required at points 4, 5, and 6.
[0059] Example 3 Seven points equipped with alkali injectors, temperature sensors, and condensate drainage devices were set up along the blast furnace gas pipeline. The gas temperature and presence of condensate at the seven points are shown in the table below.
[0060]
[0061] Condensate was discharged from point #2, and its pH value was measured to be 1.6. Alkali spraying is required at point #1. Gradually increase the flow rate of alkali solution at point #1 until the pH value of the condensate at point #2 reaches the target value of pH0=5.5.
[0062] Since condensate is also discharged from points 3#, 4#, 5#, and 6#, in addition to point 1#, points 2#, 3#, 4#, and 5# also need to be sprayed with alkaline solution.
[0063] The gas flow rate is V g =355000m 3 / h, according to formula (2), the flow rates of condensate precipitated at points 3#, 4#, 5# and 6# are V3=5395.72kg / h, V4=3245.25kg / h, V5=2416.19kg / h, and V6=783.77kg / h.
[0064] The alkaline solution used is a 5% NaOH solution with a molecular weight of 40 g / mol. The amount of alkaline solution required for points 2#, 3#, 4#, and 5# is calculated as V according to formula (1). A2 =108.41kg / h, V A3 =65.21kg / h, V A4 =48.55kg / h, V A5 =15.75kg / h.
[0065] The absence of condensate discharge at point 7 indicates that the gas temperature has stabilized from this point onwards, with little or no condensate discharge expected, which has minimal impact on pipeline corrosion. Therefore, neither point 6 nor point 7 requires alkali spraying.
[0066] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
[0067] The detailed descriptions listed above are merely specific descriptions of feasible implementation methods of this application and are not intended to limit the scope of protection of this application. All equivalent implementation methods or modifications made without departing from the spirit of the art of this application should be included within the scope of protection of this application.
Claims
1. A method for controlling the pH value of condensate in blast furnace gas pipelines, characterized in that, Includes the following steps: Several alkali injection points are set along the blast furnace gas pipeline, and alkali injection points are equipped with alkali injectors. Check if condensation is generated at each point. Turn on the alkaline spray nozzles at the points before the first point that generates condensation to the points before the last point that generates condensation, in order to neutralize the HCl dissolved in the condensation between the first and last points that generate condensation.
2. The method for controlling the pH value of condensate in blast furnace gas pipelines according to claim 1, characterized in that, The flow rate of the alkaline solution injection is: ， Among them, V An The required flow rate of alkali at the nth point, in kg / h; a = 1 or 2; c is the mass concentration of the alkali solution; V n+1 It is the flow rate of condensate produced from point n to point n+1, in kg / h; c HCl It's the acid concentration. is the target acid concentration, both in mol / kg; M is the relative molecular mass of the base, in g / mol.
3. The method for controlling the pH value of condensate in blast furnace gas pipelines according to claim 2, characterized in that, Among them, T n T is the gas temperature at the nth point. n+1 V represents the gas temperature at the (n+1)th point, in °C; e is the natural logarithm; g This is the blast furnace gas flow rate, measured in meters per second (m³). 3 / h.
4. The method for controlling the pH value of condensate in blast furnace gas pipelines according to claim 3, characterized in that, A pH meter is installed at the first point where condensate is generated to measure the pH value of the condensate.
5. The method for controlling the pH value of condensate in blast furnace gas pipelines according to claim 4, characterized in that, , = pH is the pH value of the first point where condensate is generated, and pH0 is the target pH value.
6. The method for controlling the pH value of condensate in blast furnace gas pipelines according to claim 4, characterized in that, The alkaline sprayer at the point preceding the first point where condensate is generated gradually increases the alkaline spray flow rate until the pH value at the first point where condensate is generated reaches the target pH value.
7. The method for controlling the pH value of condensate in blast furnace gas pipelines according to claim 3, characterized in that, A temperature sensor is installed at each alkali injection point to detect the gas temperature at that point.
8. The method for controlling the pH value of condensate in blast furnace gas pipelines according to claim 1, characterized in that, Each alkaline solution injection point is equipped with a condensate drainage device.
9. The method for controlling the pH value of condensate in blast furnace gas pipelines according to claim 8, characterized in that, In the direction of blast furnace gas flow, the distance between adjacent alkali injection points tends to increase.
10. The method for controlling the pH value of condensate in blast furnace gas pipelines according to claim 1, characterized in that, The blast furnace gas pipeline is equipped with insulation to reduce the amount of condensate.