High-temperature concentrated sulfuric acid concentration measuring system

Abstract

The utility model relates to the technical field of acid concentration detection devices, and discloses a high-temperature concentrated sulfuric acid concentration measurement system which comprises a gas-liquid separation unit and an acid concentration measurement unit which are communicated, and the gas-liquid separation unit is provided with an acid inlet connector, an exhaust connector and an acid discharge connector; the gas-liquid separation unit comprises a primary gas-liquid separator and a secondary gas-liquid separator, the tops of the primary gas-liquid separator and the secondary gas-liquid separator are communicated with siphon balancers, and the lower parts of the primary gas-liquid separator and the secondary gas-liquid separator are communicated with connecting pipes; three-way ball valves are arranged at the communicating positions of the siphon balancer and the first-stage gas-liquid separator as well as the siphon balancer and the second-stage gas-liquid separator; and the two three-way ball valves are communicated with the exhaust interface. According to the scheme, air bubbles in concentrated sulfuric acid at a dilution outlet can be effectively reduced through the first-stage gas-liquid separator and the second-stage gas-liquid separator, so that the measurement value of the conductivity sensor is not influenced by the air bubbles, and the measurement accuracy is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of acid concentration detection devices, and in particular to a high-temperature concentrated sulfuric acid concentration measurement system. Background Art

[0002] High-temperature concentrated sulfuric acid is primarily present in the waste heat recovery system of the sulfuric acid plant. Within this waste heat recovery system, the most critical measurement point is the concentrated sulfuric acid concentration at the diluter outlet. However, the diluter operates by introducing desalted water, compressed air, and concentrated sulfuric acid into the diluter. The compressed air then accelerates the mixing of water and concentrated sulfuric acid, reducing the sulfuric acid concentration. This lowers the concentration of concentrated sulfuric acid and allows it to absorb SO₃ more effectively. Consequently, the diluted sulfuric acid discharged from the diluter into the first stage of the waste heat recovery tower contains a significant amount of air. This makes the conductivity-based sulfuric acid analyzer installed at the diluter outlet susceptible to air interference when measuring the diluted sulfuric acid concentration, resulting in inaccurate readings. Inaccurate sulfuric acid concentration measurement leads to inaccurate PID control of the waste heat recovery system, severe corrosion of the stainless steel in the waste heat recovery tower, and safety incidents, further impacting the long-term, stable operation of the plant. Summary of the Invention

[0003] The present invention aims to provide a high-temperature concentrated sulfuric acid concentration measurement system to solve the technical problem in the prior art of low accuracy in measuring the concentration of high-temperature concentrated sulfuric acid after dilution.

[0004] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a high-temperature concentrated sulfuric acid concentration measurement system, comprising a connected gas-liquid separation unit and an acid concentration measurement unit, wherein the gas-liquid separation unit is provided with an acid inlet interface, an exhaust interface, and an acid discharge interface; the gas-liquid separation unit comprises a primary gas-liquid separator and a secondary gas-liquid separator, wherein the primary gas-liquid separator and the secondary gas-liquid separator are connected at the top with a siphon balancer and at the bottom with a connecting pipe; three-way ball valves are provided at the connection points between the siphon balancer and the primary gas-liquid separator and the secondary gas-liquid separator, and both three-way ball valves are connected to the exhaust interface.

[0005] Preferably, as an improvement, a recessed thermal resistor socket is provided at the bottom of the secondary gas-liquid separator; the acid concentration measurement unit comprises an electrically connected thermal resistor, a wire, and a conductivity sensor, the thermal resistor being inserted into the thermal resistor socket, and the conductivity sensor being connected to the secondary gas-liquid separator pipeline. This arrangement facilitates indirect contact of the thermal resistor with the concentrated sulfuric acid in the secondary gas-liquid separator, detecting a temperature signal, and transmitting the temperature signal to the conductivity sensor for comprehensive measurement of the acid concentration of the concentrated sulfuric acid.

[0006] Preferably, as an improvement, the bottom of the secondary gas-liquid separator is connected to a limiting flow tube and a measuring tube, the outlet ends of the limiting flow tube and the measuring tube are connected to form an acid discharge tube, the outlet of the acid discharge tube is an acid discharge interface, and the conductivity sensor is connected to the measuring tube.

[0007] Preferably, as an improvement, the diameter of the measuring tube is smaller than the diameter of the flow limiting tube.

[0008] Preferably, as an improvement, a flow limiting orifice plate is provided on the flow limiting tube.

[0009] Preferably, as an improvement, the exhaust port is connected to a waste heat recovery tower. The above arrangement effectively prevents the overflow of acidic gas and avoids environmental pollution.

[0010] Preferably, as an improvement, the acid inlet interface is located in the middle of the first-stage gas-liquid separator, and the acid discharge interface is connected to the waste heat recovery circulation tank.

[0011] Preferably, as an improvement, both end surfaces of the connecting pipe are closed, and a plurality of small holes are opened on both end surfaces.

[0012] Preferably, as an improvement, the number of the connecting pipes is two. The above arrangement effectively improves the flow efficiency of concentrated sulfuric acid in the two-stage gas-liquid separator, thereby improving the separation efficiency.

[0013] Preferably, as an improvement, it further comprises a shell, and the gas-liquid separation unit and the acid concentration measurement unit are both arranged in the shell.

[0014] Preferably, as an improvement, a heat insulation baffle is provided in the shell, which divides the space inside the shell into a separation chamber and a measuring chamber. The separation chamber shell is provided with heat dissipation holes, and the measuring chamber shell is provided with ventilation holes at the position corresponding to the conductivity sensor.

[0015] Preferably, as an improvement, the conductivity sensor and the gas-liquid separator are connected by flange bolts, and the thermal resistor and the thermal resistor sleeve are threadedly connected.

[0016] The principles of this program are:

[0017] In actual application, the acid concentrations at the diluter outlets A and B are connected to a set of gas-liquid separation units and acid concentration measurement units respectively. Concentrated sulfuric acid containing air bubbles is separated from large air bubbles in the primary gas-liquid separator and then enters the secondary gas-liquid separator to separate the remaining small air bubbles. The separated air is diverted by the siphon balancer at the top of the primary gas-liquid separator and the secondary gas-liquid separator, and then enters the exhaust interface and returns to the waste heat recovery tower, which can effectively avoid the overflow of acidic gas and avoid polluting the environment. Furthermore, the two sealed ends and small holes of the connecting pipe form an anti-vortex device, effectively eliminating vortices generated by concentrated sulfuric acid entering the primary gas-liquid separator. This prevents vortices from carrying air to the conductivity sensor and affecting acid concentration measurements. For sulfuric acid entering the conductivity sensor's measuring line after gas-liquid separation pretreatment, using a smaller diameter measuring tube (e.g., φ16) and reducing the flow rate allows for more accurate conductivity sensor measurements. The siphon balancer at the top of the separator also reduces the impact of negative pressure in the acid discharge pipe on the preceding separation device and conductivity measurement device, smoothing the concentrated sulfuric acid flow rate and preventing excessive flow within the measuring pipe, which could reduce measurement accuracy. After analysis, the concentrated sulfuric acid returns to the waste heat recovery tank through the acid discharge pipe.

[0018] The advantages of this solution are:

[0019] 1. Compared with the existing technology in which the acid concentration measurement accuracy of high-temperature concentrated sulfuric acid after dilution is low, this solution can effectively reduce the air bubbles in the concentrated sulfuric acid at the dilution outlet through the first-level gas-liquid separation and the second-level gas-liquid separator, so that the measurement value of the conductivity sensor is not affected by air bubbles, thereby effectively improving the measurement accuracy.

[0020] 2. The acid discharge interface is lower than the outlet of the separator. The height difference between the two causes a large negative pressure to be generated at the drainage interface (taking a height difference of 3m as an example, an acid discharge negative pressure of -52KPa will be generated). This solution sets a siphon balancer and then sets a measuring tube with a diameter smaller than the flow-limiting tube. By reducing the pipe diameter, the internal pressure of the two-stage separator is effectively balanced, and the impact of the negative pressure of the acid discharge pipe on the previous separation device and the conductivity measurement device is reduced. At the same time, the air separated from the two-stage gas and liquid can be discharged more smoothly. In addition, the applicant has also found through long-term experiments that when the diameter of the measuring tube where the sensor is located is reduced and it works together with the siphon balancer, on the one hand, there is no air in the sulfuric acid liquid flowing through the sensor, thereby effectively avoiding the influence of air on the acid concentration measurement. On the other hand, the combination of the two can also make the sulfuric acid at the sensor outlet a positive pressure, avoiding the influence of the height difference negative pressure on the measurement results.

[0021] 3. In this solution, the measuring tube of the conductivity sensor adopts a small diameter to effectively control the flow of concentrated sulfuric acid, thereby avoiding large flow impacting the conductivity sensor, making the measurement results of the conductivity sensor more accurate.

[0022] 4. In this solution, a flow limiting orifice is provided on the flow limiting pipe connected to the bottom of the secondary gas-liquid separator, which effectively avoids the lag in the conductivity sensor measuring the acid concentration due to excessive analysis flow, and further facilitates the waste heat recovery system to accurately implement PID control and safety protection based on the acid concentration measurement data.

[0023] 5. In this solution, the gas-liquid separator housing is designed with heat dissipation ports and heat insulation baffles. Because the measuring medium is high-temperature concentrated sulfuric acid, the temperature is usually 200°C. A heat insulation baffle is provided between the two-stage gas-liquid separation device and the conductivity sensor measurement. At the same time, the conductivity sensor is provided with ventilation holes on the box to prevent the sensor from being damaged by high temperature.

[0024] 6. This solution effectively prevents the overflow of acidic gases and environmental pollution by connecting the exhaust port to a waste heat recovery tower. Connecting the acid discharge pipe to a waste heat recovery circulation tank facilitates the recycling of diluted concentrated sulfuric acid after acid concentration measurement, achieving continuous absorption and acid production of SO3. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic structural diagram of Example 1 of a high-temperature concentrated sulfuric acid concentration measurement system of the present invention.

[0026] Figure 2 This is a cross-sectional schematic diagram of Example 1 of the high-temperature concentrated sulfuric acid concentration measurement system of the present invention.

[0027] Figure 3 This is a real-time acid concentration measurement curve diagram when using the high-temperature concentrated sulfuric acid concentration measurement system in Comparative Example 1 and direct measurement in Comparative Example 2 (the green curve is the acid concentration measurement curve after diluter outlet A adopts Comparative Example 1, and the blue curve is the acid concentration measurement curve after diluter outlet B adopts Comparative Example 2).

[0028] Figure 4 This is a real-time acid concentration measurement curve diagram when the high-temperature concentrated sulfuric acid concentration measurement system in Example 1 of the present invention is used (the green curve is the acid concentration measurement curve at diluter outlet A, and the blue curve is the acid concentration measurement curve at diluter outlet B). DETAILED DESCRIPTION

[0029] The following is further described in detail through specific implementation methods:

[0030] The figure marks in the drawings of the specification include: shell 1, thermal insulation baffle 11, heat dissipation hole 12, ventilation hole 13, thermal resistor 21, conductivity sensor 22, acid inlet interface 31, exhaust interface 32, acid discharge interface 33, primary gas-liquid separator 41, secondary gas-liquid separator 42, connecting pipe 43, siphon balancer 44, ball valve 45, thermal resistor sleeve 46, flow limiting tube 47, flow limiting orifice 471, measuring tube 48, acid discharge tube 49.

[0031] The high-temperature concentrated sulfuric acid concentration measurement system in this scheme can be installed at multiple nodes in the sulfuric acid device according to actual needs. This scheme specifically takes the installation at the diluter outlet as an example to detail the structure of the high-temperature concentrated sulfuric acid measurement system in this scheme.

[0032] Example 1

[0033] This solution provides a high-temperature concentrated sulfuric acid concentration measurement system, basically as shown in the attached Figure 1 and Figure 2 As shown: it includes a gas-liquid separation unit and an acid concentration measurement unit connected to each other and a shell 1, and the gas-liquid separation unit and the acid concentration measurement unit are both arranged in the shell 1.

[0034] The acid concentration measuring unit includes a thermal resistor 21 , a wire, and a conductivity sensor 22 that are electrically connected.

[0035] The gas-liquid separation unit is provided with an acid inlet interface 31, an exhaust interface 32, and an acid discharge interface 33. As a reference, the gas-liquid separation unit in this embodiment includes a primary gas-liquid separator 41 and a secondary gas-liquid separator 42. The primary gas-liquid separator 41 and the secondary gas-liquid separator 42 are connected at the top with a siphon balancer 44 and at the bottom with a connecting pipe 43. As a reference, the number of connecting pipes 43 in this embodiment is two, which facilitates the rapid flow of concentrated sulfuric acid in the two-stage gas-liquid separators, thereby improving the separation efficiency. In addition, both end faces of the connecting pipe 43 are closed, and a number of small holes are provided on both end faces, which effectively eliminates the vortex generated by concentrated sulfuric acid entering the primary gas-liquid separator 41, facilitates the sulfuric acid in the primary gas-liquid separator 41 to flow smoothly through the connecting pipe 43, and does not generate a vortex when entering the secondary gas-liquid separator 42, thereby effectively avoiding the air carried by the vortex to the position of the conductivity sensor 22 and affecting the acid concentration measurement.

[0036] Three-way ball valves 45 are installed at the connection points between the siphon balancer 44 and the primary gas-liquid separator 41 and the secondary gas-liquid separator 42. Both three-way ball valves 45 are connected to the exhaust port 32. For reference, the exhaust port 32 is connected to the waste heat recovery tower to effectively prevent the overflow of acidic gases and avoid environmental pollution. The acid inlet port 31 is located in the middle of the primary gas-liquid separator 41. For reference, in this embodiment, the acid inlet port 31 is connected to the diluter outlet, facilitating gas-liquid separation and acid concentration measurement of the concentrated sulfuric acid discharged from the diluter.

[0037] The lower portion of the secondary gas-liquid separator 42 is provided with a recessed thermal resistor socket 46, into which the thermal resistor 21 is inserted, facilitating measurement of the temperature signal of the concentrated sulfuric acid in the secondary gas-liquid separator 42. The bottom of the secondary gas-liquid separator 42 is connected to a flow limiting tube 47 and a measuring tube 48. The conductivity sensor 22 is connected to the measuring tube 48, and the diameter of the measuring tube 48 is smaller than that of the flow limiting tube 47, thereby improving measurement accuracy. The flow limiting tube 47 is provided with a flow limiting orifice 471, which effectively prevents excessive flow from the bottom, which could cause the conductivity sensor 22 to measure the acid concentration lag. The outlet ends of the flow limiting tube 47 and the measuring tube 48 are connected to form an acid discharge pipe 49, which exits at the acid discharge port 33. For reference, in this embodiment, the acid discharge port 33 is connected to a waste heat recovery circulation tank, allowing the concentrated sulfuric acid discharged from the diluter to reabsorb SO3 and produce acid after gas-liquid separation and acid concentration measurement.

[0038] An insulating baffle 11 is provided in the outer shell 1, which divides the space inside the outer shell 1 into a separation chamber and a measuring chamber. The first-level gas-liquid separator 41 and the second-level gas-liquid separator 42 are located in the separation chamber, and the separation chamber shell is provided with a heat dissipation hole 12; the conductivity sensor 22 is located in the measuring chamber, and the measuring chamber shell is provided with a ventilation hole 13 at the position corresponding to the conductivity sensor 22.

[0039] The specific implementation process is as follows:

[0040] In actual application, the acid concentrations at the two points A and B of the diluter outlet are respectively connected to a set of gas-liquid separation units and acid concentration measurement units. The concentrated sulfuric acid containing air bubbles is separated from the large air bubbles in the first-level gas-liquid separator 41, and then enters the second-level gas-liquid separator 42, where the remaining small air bubbles are separated. The separated air is diverted by the siphon balancer 44 at the top of the first-level gas-liquid separator 41 and the second-level gas-liquid separator 42, and then enters the exhaust interface 32 and returns to the waste heat recovery tower, which can effectively avoid the overflow of acidic gas and avoid polluting the environment. At the same time, the closed end face and small hole of the connecting pipe 43 constitute an anti-vortex device, which effectively eliminates the vortex generated by the concentrated sulfuric acid entering the first-level gas-liquid separator 41, allowing the concentrated sulfuric acid to flow smoothly into the second-level gas-liquid separator 42 for secondary gas-liquid separation, thereby preventing the air carried by the vortex from reaching the position of the conductivity sensor 22 and affecting the acid concentration measurement; the sulfuric acid that has been pretreated by gas-liquid separation enters the measuring tube 48 line of the conductivity sensor 22. Using a measuring tube 48 with a smaller diameter (such as φ16) to reduce the flow rate can make the conductivity sensor 22 more accurate when measuring. The siphon balancer 44 at the upper end of the separator can also reduce the impact of the negative pressure of the acid discharge pipe 49 on the previous separation device and conductivity measurement device, smooth the concentrated sulfuric acid flow rate, and avoid the concentrated sulfuric acid from flowing too fast in the measuring tube 48 and reducing the measurement accuracy. After analysis, the concentrated sulfuric acid returns to the waste heat recovery circulation tank through the acid discharge pipe 49.

[0041] Comparative Example 1

[0042] The difference between this comparative example and Example 1 is that there is only a primary gas-liquid separator, and there is no secondary gas-liquid separator and siphon balancer.

[0043] Comparative Example 2

[0044] The difference between this comparative example and Example 1 is that the high-temperature concentrated sulfuric acid concentration measurement system in this solution is not provided, and the diluter outlet is directly connected to the conductivity measuring device.

[0045] Experimental Example 1: Impact on acid discharge, exhaust stability, and acid concentration measurement stability

[0046] Real-time detection of the data curves of acid discharge negative pressure, exhaust pressure, acid concentration measurement in Example 1 and Comparative Examples 1-2. The results are detailed in Figures 3-4 .

[0047] In practical applications:

[0048] In Example 1, both outlets A and B of the diluter are connected to a set of high-temperature concentrated sulfuric acid concentration measurement system of this scheme, that is, the acid concentrations at the two points A and B are connected to a set of gas-liquid separation unit and acid concentration measurement unit respectively, for real-time monitoring of the acid concentration after dilution. The results of the acid concentration real-time measurement curve are detailed in Figure 4 .

[0049] In Comparative Example 1, the high-temperature concentrated sulfuric acid concentration measurement system (only the first-stage separator) is connected to the diluter outlet A to detect the acid concentration at outlet A. The acid concentration real-time measurement curve results are as follows: Figure 3 Shown as the green curve in the middle.

[0050] In comparative example 2, the conductivity measuring device is directly connected to the diluter outlet B to detect the acid concentration at the outlet B. The acid concentration real-time measurement curve result is as follows: Figure 3 Shown as the blue curve.

[0051] The results show that the equipment in Example 1 (i.e., the high-temperature concentrated sulfuric acid concentration measurement system) effectively balances the stability of exhaust and acid discharge, and its pressure curve does not fluctuate much (e.g., Figure 4 As shown). In addition, the acid concentration measurement curve in the embodiment is relatively stable and tends to be a horizontal line. The display can accurately and stably measure the acid concentration, providing a guarantee for precise control of PID.

[0052] In contrast, in Comparative Example 1, due to the lack of a secondary gas-liquid separator and a siphon balancer, the exhaust gas is easily affected by the negative pressure formed by high-difference acid discharge, resulting in large fluctuations in the exhaust pressure (e.g. Figure 3(shown as the green curve in the middle). Furthermore, because there is only one primary gas-liquid separator, some gas is still present in the acid discharge, causing the negative pressure generated by the high-difference acid discharge to be unstable and fluctuate significantly. Specifically, the applicant discovered through long-term experiments that when using a primary gas-liquid separator with an effective volume of 5L, the maximum gas separation volume is 10L / min, and the primary gas separation efficiency is only 85%. This results in 15% gas remaining in the acid discharge, thus affecting the stability of the negative pressure. Furthermore, residual gas in the acid solution also enters the measuring tube along with the acid solution, further affecting the accuracy of acid concentration measurements.

[0053] In Comparative Example 2, the conductivity measuring device is directly connected to the diluter outlet B, which is more serious than the situation in Comparative Example 1. The diluted concentrated sulfuric acid contains a large amount of gas, which is directly discharged to the conductivity measuring device to measure the acid concentration, causing the acid concentration measurement result to fluctuate greatly, significantly reducing the PID control accuracy (such as Figure 3 (shown as the middle blue curve). In summary, compared to the existing technology without a gas-liquid separator, this solution, by installing a gas-liquid separator and a siphon balancer, effectively improves the stability of acid concentration measurement results, ensuring that they are essentially consistent with the actual concentration, stabilizing system monitoring and improving production efficiency. However, at locations without a gas-liquid separator, acid concentration measurement results fluctuate significantly and detection accuracy is low, thus affecting PID control precision.

[0054] The above is only an embodiment of the present invention, and the common knowledge such as the specific technical solutions and / or characteristics in the solution are not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the description can be used to interpret the content of the claims.

Claims

1. A high-temperature concentrated sulfuric acid concentration measurement system, characterized by: It includes a connected gas-liquid separation unit and an acid concentration measuring unit, and the gas-liquid separation unit is provided with an acid inlet interface, an exhaust interface, and an acid discharge interface; the gas-liquid separation unit includes a primary gas-liquid separator and a secondary gas-liquid separator, and the primary gas-liquid separator and the secondary gas-liquid separator are connected to a siphon balancer at the top and a connecting pipe at the bottom; three-way ball valves are provided at the connection between the siphon balancer and the primary gas-liquid separator and the secondary gas-liquid separator, and both three-way ball valves are connected to the exhaust interface.

2. A high-temperature concentrated sulfuric acid concentration measurement system according to claim 1, characterized in that: A recessed thermal resistor sleeve is provided at the lower part of the secondary gas-liquid separator; the acid concentration measuring unit comprises an electrically connected thermal resistor, a wire and a conductivity sensor, the thermal resistor is inserted into the thermal resistor sleeve, and the conductivity sensor is connected to the secondary gas-liquid separator pipeline.

3. A high-temperature concentrated sulfuric acid concentration measurement system according to claim 2, characterized in that: The bottom of the secondary gas-liquid separator is connected to a flow limiting tube and a measuring tube. The outlet ends of the flow limiting tube and the measuring tube are connected to form an acid discharge tube. The outlet of the acid discharge tube is an acid discharge interface. The conductivity sensor is connected to the measuring tube.

4. A high-temperature concentrated sulfuric acid concentration measurement system according to claim 3, characterized in that: The diameter of the measuring tube is smaller than the diameter of the flow restricting tube.

5. A high-temperature concentrated sulfuric acid concentration measurement system according to claim 3, characterized in that: The flow limiting tube is provided with a flow limiting orifice.

6. A high-temperature concentrated sulfuric acid concentration measurement system according to claim 1, characterized in that: The acid inlet interface is located in the middle of the first-level gas-liquid separator, the exhaust interface is connected to the waste heat recovery tower, and the acid discharge interface is connected to the waste heat recovery tower circulation tank.

7. The high-temperature concentrated sulfuric acid concentration measurement system according to claim 1, characterized in that: Both end surfaces of the connecting pipe are closed, and a plurality of small holes are opened on both end surfaces.

8. A high-temperature concentrated sulfuric acid concentration measurement system according to claim 7, characterized in that: There are two connecting pipes.

9. A high-temperature concentrated sulfuric acid concentration measurement system according to any one of claims 1 to 8, characterized in that: It also includes a shell, and the gas-liquid separation unit and the acid concentration measuring unit are both arranged in the shell.

10. A high-temperature concentrated sulfuric acid concentration measurement system according to claim 9, characterized in that: The shell is provided with a heat insulation baffle, which divides the space inside the shell into a separation chamber and a measuring chamber. The measuring chamber shell is provided with heat dissipation holes, and the measuring chamber shell is provided with ventilation holes at the position corresponding to the conductivity sensor.

Images