Desulfurizing absorption tower slurry density measuring system

Abstract

The invention provides a desulfurizing absorption tower slurry density measuring system which comprises a slurry inlet channel connected with a slurry outlet of an absorption tower, a slurry outlet channel for introducing measured slurry into a pit, and an expansion device for receiving the slurry from the slurry inlet channel and separating the slurry, the emptying device is located at the top of the expansion device and used for emptying gas, the density measuring device is used for measuring density, and a slurry outlet in the bottom of the expansion device is communicated with the density measuring device. The slurry density can be measured more accurately, and the accuracy of the device is improved.

Description

Technical Field

[0001] The invention relates to a limestone-gypsum wet flue gas desulfurization process, and in particular to a limestone-gypsum wet flue gas desulfurization absorption tower slurry density measurement system. Background Art

[0002] The limestone-gypsum wet flue gas desulfurization process, also known as wet flue gas desulfurization, is a common environmentally friendly technology for removing sulfur dioxide from flue gas. The basic principle of this process is to use limestone to react with SO2 in flue gas to form gypsum, thereby capturing sulfur dioxide and removing it from flue gas. The flue gas is first directed into an absorption tower, which is usually a tall tower-shaped structure. In the absorption tower, limestone (usually limestone slurry) is sprayed into the flue gas in the form of a suspension, and the SO2 in the flue gas reacts chemically with the limestone suspension. Sulfur dioxide is converted into gypsum, and limestone is converted into calcium hydroxide. Gypsum is generated in the absorption tower in the form of a suspension and deposited into the suspension. The suspension containing the generated gypsum flows out from the bottom of the absorption tower and enters a separator or sedimentation tank. Here, the gypsum particles gradually settle to the bottom, and the purified liquid is extracted from the top. Ideally, a portion of the purified liquid contains a small amount of unreacted limestone and gypsum particles and is recycled back to the absorber to continue capturing sulfur dioxide. The other portion of the liquid needs to be treated for solid waste and pollutants to ensure that the discharged water quality meets environmental regulations.

[0003] In the limestone-gypsum wet flue gas desulfurization process, the density of the slurry in the absorption tower is a very important indicator, which is an important parameter that directly determines the quality of gypsum products. At present, most power plants have undergone ultra-clean emission transformation. During the transformation, the original Roots blower was replaced with a multi-stage centrifugal blower due to its high noise and low efficiency. At the same time, in order to increase the oxidation effect, the oxidation air pipe network in the original absorption tower was removed and replaced with an oxygen lance.

[0004] In the limestone-gypsum wet flue gas desulfurization process, the slurry density is usually measured to ensure that the concentration of gypsum and limestone in the reaction liquid is within an appropriate range to maintain the effectiveness of the desulfurization reaction. Density measurement can be done in a variety of ways, including buoyancy / immersion method, where a densitometer or float is immersed in the slurry and its buoyancy is measured. According to the Archimedes principle, the buoyancy is proportional to the density of the liquid. By comparing the buoyancy with the weight of the float of a known volume, the density of the liquid can be calculated. Dew point measurement can also be used, which is usually used to determine the water content in steam. In the wet flue gas desulfurization process, this method can be used to measure the moisture content in the slurry and estimate the density. There are also methods such as oscillating tube method, radioactive measurement method, capacitance method, etc. that can also determine the slurry density. In industrial production, the buoyancy / immersion method is used more frequently due to cost considerations.

[0005] When measuring the slurry density, the oxygen lance penetrates deep into the bottom of the absorption tower, causing an increase in the number of bubbles in the absorption tower slurry. The gypsum discharge pump pumps out the absorption tower slurry containing a large number of bubbles and passes it through the density meter pipeline to measure the absorption tower slurry density. Because the slurry contains a large number of bubbles, the presence of gas or bubbles will cause inaccurate measurements by the density meter.

[0006] Chinese invention patent document CN 102928316A (and utility model patent document CN202869917U filed on the same day) discloses a desulfurized gypsum slurry density measuring device, comprising: a sampling unit, a liquid infusion pipeline and a measuring unit connected in sequence, the sampling unit comprising a slurry absorption pipe, the slurry absorption pipe being connected to a flow control valve, the measuring unit comprising a slurry storage tank, the slurry storage tank being connected to a static pressure level gauge, and the slurry absorption pipe being connected to the slurry storage tank via a liquid infusion pipeline.

[0007] The document discloses that the method of avoiding air interference is to seal the connection between the infusion pipeline and the slurry absorption pipe and the slurry storage tank to avoid interference from impure air and ensure more precise control. However, in addition to the interference of external air, the bubbles in the slurry in the absorption tower caused by the oxygen gun penetrating into the bottom of the absorption tower are a more important factor affecting the density measurement. The technology in this document cannot solve the impact of bubbles generated inside. In addition, the document's special sampling unit performs one-time sampling and then independently determines its density. It cannot measure the slurry density in real time. It may even be necessary to interrupt the operation of the original gypsum line for sampling, which is not convenient for sampling.

[0008] Chinese invention patent document CN 109297859A (and utility model patent document CNCN209387451U filed on the same day) discloses a device for measuring density and pH of gypsum slurry in a wet flue gas desulfurization device, comprising a density meter (4), a pH value measuring box (5) and a pH meter (6), wherein the device is characterized in that: the main pipeline of the device is provided with a slurry inlet door (2), a defoaming box (3), a density meter (4), a pH value measuring box (5), a slurry outlet door (7), a manual sampling box (8) and a pit (17) in the order of the slurry flow direction; the pH meter (6) is located in the pH value measuring box (5); the main pipeline is connected to an absorption tower; An inlet filter (1) is provided at the joint; the defoaming box (3) is connected to the process water tank (9) via a defoaming agent adding pipeline and a process water flushing pipeline, wherein the defoaming agent adding pipeline is sequentially connected to a process water inlet gate (10), a defoaming agent storage tank (11), a metering pump (12) and a metering pump outlet valve (13) in the process water flow direction; an automatic liquid adding device is provided on the defoaming agent adding pipeline, and the automatic liquid adding device comprises a liquid level meter (14) arranged in the defoaming agent storage tank (11) and an image recognition device (15) arranged in the defoaming box (3); and a process water flushing valve (16) is provided on the process water flushing pipeline.

[0009] The document claims that its technology can automatically detect the density and pH value of the slurry, and can be manually detected for comparison. In addition, the defoaming agent addition pipeline and automatic liquid adding device can automatically defoam the slurry, ensuring the accuracy and stability of the measurement results, reducing labor intensity, improving work efficiency, and reducing maintenance costs. However, this technology uses defoaming agents to treat foam, which only solves the problem of no foam. The gas in the bubbles cannot be discharged or separated, and it still cannot solve the impact of the gas in the bubbles introduced by the oxygen gun on the accuracy of density measurement.

[0010] Chinese utility model patent document CN 216847352U discloses a gypsum slurry defoaming and density measurement system outside a limestone-gypsum desulfurization tower, comprising an absorption tower filled with gypsum slurry, the slurry discharge port of the absorption tower being connected to a gas-liquid separator via a slurry supply pipe, the top outlet of the gas-liquid separator being connected to a ditch via an exhaust pipe, the bottom outlet of the gas-liquid separator being connected to a density meter via a slurry discharge pipe, and the outlet of the density meter being connected to the ditch via a pipe.

[0011] The document claims that when the technology is used, the gypsum slurry mixed with bubbles in the absorption tower flows to the gas-liquid separator under the action of the static pressure of the slurry. After gas-liquid separation by gravity sedimentation in the gas-liquid separator, the gas is discharged from the top outlet of the gas-liquid separator and the gypsum slurry is discharged from the bottom outlet of the gas-liquid separator. The gas then flows through the density meter to measure the density of the gypsum slurry. The gypsum slurry is finally discharged into the ditch. The technology is easy to use. Furthermore, since the gas can be discharged through the top outlet of the gas-liquid separator, the adverse effects of bubbles on the density measurement of the gypsum slurry are eliminated. The density meter can provide stable and accurate gypsum slurry density values, thereby providing more reliable gypsum slurry density values ​​for the operation of the absorption tower.

[0012] However, since the gas discharge is separated only by the gravity sedimentation of the slurry in the gas-liquid separator, the gas is separated from the upper part. In fact, since the bubbles are inside the slurry, it is difficult for them to passively separate from the slurry without settling and rising to the top of the gas-liquid separator. Instead, they may still settle with the slurry, so the influence of gas on density measurement cannot be truly eliminated.

[0013] In summary, when measuring the slurry density of the limestone-gypsum desulfurization tower, the problem of inaccurate density meter measurement due to the increase of bubbles in the slurry of the absorber tower caused by the oxygen lance penetrating into the bottom of the absorber tower has not been truly solved. Summary of the invention

[0015] To solve the above problems, the present invention provides a desulfurization absorption tower slurry density measurement system, comprising a slurry inlet channel connected to the slurry outlet of the absorption tower and a slurry outflow channel for introducing the measured slurry into a pit, an expansion device for receiving the slurry from the slurry inlet channel and performing slurry separation, an emptying device located at the top of the expansion device for exhausting gas, a density measuring device for measuring density, and the bottom slurry outlet of the expansion device is connected to the density measuring device.

[0016] Preferably, the total volume of the expansion device of the present invention is greater than the total volume of the slurry entering the channel, preferably greater than or equal to 10 times.

[0017] Preferably, the top of the density measuring device of the present invention is connected to the emptying device. Meanwhile, the bottom slurry outlet of the expansion device is connected to the bottom of the density measuring device.

[0018] Further preferably, the highest level of the density measuring device is lower than the highest level of the capacity expansion device.

[0019] Furthermore, the slurry outlet of the present invention is located at the lower part of the absorption tower.

[0020] Further preferably, the position where the slurry entry channel of the present invention communicates with the expansion device is located at the upper part of the expansion device.

[0021] Furthermore, the slurry of the present invention enters the slurry inlet channel from the slurry outlet of the absorption tower by static pressure.

[0022] Preferably, the present invention further comprises a pH measuring device for determining the pH value, a flow control valve at each location for controlling the slurry flow rate, and a flushing water inlet for cleaning each location.

[0023] More preferably, the expansion device of the present invention is cylindrical in the middle, and has a conical structure with a bottom and a top that narrows downward and upward, respectively.

[0024] The present invention has the following beneficial effects: The present invention utilizes static pressure to lead the absorption tower slurry led out of the slurry outlet at the bottom of the limestone-gypsum desulfurization absorption tower to the density measurement system of the present invention for density measurement, which is completely independent of the gypsum operation line, and does not require the operation of the gypsum discharge pump on the gypsum operation line, thereby saving the operation power consumption of the gypsum discharge pump. In the present invention, the desulfurization absorption tower slurry enters the expansion device through static pressure for separation treatment, the expansion device diverts the bubbles in the slurry, and the bubbles overflow to the emptying device through the expansion tank, and the slurry obtained at the bottom of the expansion device passes through the density measurement device through static pressure flow, and does not need to be associated with the operation of the absorption tower and gypsum.

[0025] The present invention adds a pretreatment unit before measuring the slurry density, and uses an expansion device to separate the absorber slurry from the bubbles therein, thereby eliminating the influence of the bubbles on the density meter measurement and improving the accuracy of the density meter measurement. The expansion device diverts and separates the bubbles in the slurry, which can help reduce the interference of the bubbles in subsequent processing. The bubbles may affect the accuracy of the density measuring device and may also affect the treatment effect of the slurry in some cases. On the other hand, the absorber slurry is pretreated before entering the expansion device, which may include removing impurities, particulate matter or other unnecessary components. Pretreatment can improve the efficiency of subsequent processing steps and reduce possible damage or blockage to the equipment. At the same time, the bubbles overflow to the emptying device through the expansion tank. The design of this emptying device can effectively separate the gas from the slurry and avoid problems caused by the gas in subsequent processing steps. After the slurry comes out from the bottom of the expansion device, it passes through the density measuring device from bottom to top and after the density is measured by the density measuring device, its top is connected to the emptying device. The horizontal height of the expansion device is lower than the emptying device, and the horizontal height of the highest point of the density measuring device is lower than the horizontal height of the highest point of the expansion device. Such a design can make full use of static pressure to flow the slurry. When the slurry flows through the density measuring device from bottom to top, a more stable flow state can be ensured, and the measurement error caused by violent agitation of the fluid is reduced, which helps to obtain more accurate slurry density information. The top of the density measuring device is connected to the emptying device, which can further tend to gather the remaining gas at the top, so that it is easier to be emptied again. This design can improve the efficiency of the emptying device for gas separation, thereby more effectively removing bubbles. This design can also reduce the maintenance frequency of the system. The slurry flows into the emptying device from bottom to top, which can reduce solid particles or sediments that may adhere to the bottom of the emptying device.

[0026] The slurry density measurement system of the present invention can realize continuous monitoring of the slurry density of the absorption tower, and can monitor the qualified situation of the slurry density in real time and continuously. The gypsum operation line will be operated only when the slurry density is qualified, thereby improving the operation reliability of the overall device.

[0027] The present invention only adds an expansion tank, without adding other equipment or using additional raw materials. It has a simple structure, is easy to assemble, and has a long service life. At the same time, the present invention also includes flushing and control valves. During the operation of the system, some by-products such as solid particles and gypsum scaling may be generated. The cleaning device can regularly or continuously remove these by-products to prevent them from accumulating in the equipment, thereby maintaining the normal operation of the equipment. The cleaning device can regularly remove the accumulated particles and scaling to reduce the risk of clogging and corrosion of the equipment. The presence of the cleaning device can effectively extend the service life of the equipment. By regularly removing pollutants such as solid particles and scaling, the chance of equipment damage can be reduced, and the frequency of maintenance and replacement of equipment can be further reduced, saving costs.

[0028] In summary, the desulfurization absorption tower slurry density measuring device described in the present invention saves equipment such as water pumps, saves energy, helps the slurry flow through static pressure, and improves the reliability of the device. At the same time, the density measuring device can measure the slurry density more accurately, thereby improving the accuracy of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the overall structure of Example 1 of the present invention.

[0030] Figure 2 It is an enlarged schematic diagram of the capacity expansion device in Example 2 of the present invention. DETAILED DESCRIPTION

[0031] The following is further described in detail through specific implementation methods. However, it should be pointed out that the following embodiments of the present invention are only for better illustrating the content of the present invention, but do not mean that the content of the present invention is limited to the examples. Therefore, those skilled in the art can make non-essential improvements and adjustments to the implementation scheme according to the above invention content, which still belongs to the protection scope of the present invention and is subject to the protection scope of the attached claims.

[0032] Example 1 A desulfurization absorption tower slurry density measurement system includes a slurry inlet channel connected to a slurry outlet at the bottom of an absorption tower 1 and a slurry outflow channel for introducing measured slurry into a pit. All slurry channels use DN50 pipes (i.e., pipes with a circumference of 50 mm). The expansion device 2 is used to receive the slurry from the slurry inlet channel and separate the slurry, the expansion device 2 is cylindrical, and its circumference is larger than the circumference of the slurry channel; the position where the slurry inlet channel is connected to the expansion device 2 is located at the upper part of the expansion device 2, the emptying device 4 for exhausting the gas is located at the top of the expansion device 2, and the density measuring device 3 for measuring the density, the bottom slurry outlet of the expansion device 2 is connected to the bottom of the density measuring device 3, and the top of the density measuring device 3 is connected to the emptying device 4; wherein the highest point of the density measuring device 3 is slightly lower than the highest point of the top of the expansion device 2, ensuring that the density meter measuring device can be fully filled to achieve the accurate measurement conditions of the density meter; and the height of the inlet position of the exhaust pipe entering the emptying device 4 from the top of the expansion device 2 is about 10 cm higher than the height of the outlet position of the pipe connecting the emptying device 4 to the pit, ensuring that the exhaust pipe at the top of the expansion device 2 only discharges bubbles, does not discharge the absorption tower slurry, and can only discharge the slurry into the pit through the emptying device 4.

[0033] In the system of the present invention, a pH measuring device 7 for measuring the pH value is also provided before entering the expansion device. A flow control valve for controlling the slurry flow rate and a flushing water inlet 5 for cleaning various parts are provided at the slurry inlet channel, the slurry outflow channel, and the connection points of each component. In this embodiment, a flushing water inlet 5 is provided before the inlet of the expansion device 2 and after the bottom outlet. In the present invention, the slurry in the absorption tower is pre-treated by static pressure to the expansion device, so that the bubbles and the slurry are fully dispersed. The expansion device diverts the bubbles in the slurry, and the bubbles overflow to the emptying device through the expansion tank, and the slurry discharged from the bottom of the expansion device passes through the density measuring device through the static pressure flow. The expansion device of the present invention uses an expansion tank, whose volume or size is larger than the slurry entry channel (DN50 pipe), so that the system pressure is reduced after the volume is expanded, so that the gas components are more easily vaporized to form gas and enter the emptying device from above. In order to fully separate the gas, a temperature and pressure regulating device is also provided in the expansion device to make the gas components more easily vaporized and overflowed.

[0034] A flow guide device is also provided at the bottom of the expansion device to help guide the bubbles to float upward, which is achieved by flow direction design, flow channel shape, etc., to ensure that the bubbles are effectively guided to the upper part. A bubble overflow port is provided at the top of the expansion device to ensure that the bubbles can be discharged from the upper part of the expansion device to the emptying device. At the same time, in order to avoid reverse flow, a flow direction controller is also provided inside the expansion device. A wave or vibration device is introduced inside the expansion device to help the bubbles float up more easily and be separated. A gas collection area and a gas outlet are provided at the upper part of the expansion device so that the gas can gather at the upper part and be discharged. These designs are conventional designs in the prior art, and those skilled in the art can select the design as needed. A stirring device is also provided in the expansion device for appropriate stirring or mixing to ensure that the components in the slurry are fully mixed (a flushing water pipeline is provided at the bottom of the expansion device, and the expansion device is regularly flushed and cleaned to ensure the reliability of gas-liquid separation of the expansion device).

[0035] In the present invention, the slurry processed by the expansion device passes through the density measuring device from bottom to top, which can ensure a more stable flow state and reduce the measurement error caused by violent agitation of the fluid. The density measuring device can adopt a common density meter in the art, such as a tuning fork density meter, a float density meter, a static pressure density meter, etc.

[0036] The flushing device of the present invention can flush all parts of the entire device after closing the device valve, and reopen the density measurement system after the flushing device completes the flushing operation. The closing cycle of the main valve of the device is 2 hours / time. The cleaning device can keep the inside of the equipment clean and stable, which helps to maintain the normal operation of the equipment. Contaminants and blockages in the equipment may cause unstable operation and affect the continuity and reliability of the production process.

[0037] Example 2 A desulfurization absorption tower slurry density measurement system, except for the specific structure of the expansion device 2, other structures are the same as those of Example 1.

[0038] like Figure 2 As shown, the middle part of the expansion device 2 is still a cylindrical structure, but the bottom and top are changed to conical structures that shrink downward and upward respectively, and the taper is 106 degrees (of course, a smaller angle can also be used). This design can ensure that the slurry in the expansion device is in a flowing state for a long time, prevent the slurry particles from being deposited on the wall and bottom of the expansion device, and further prevent the sediment from causing inaccurate measurement of the slurry density in the absorption tower. Figure 2 The total volume of the expansion device 2 is about 0.603m³, which is larger than the total volume of the slurry channel (DN50 pipe) of 0.006m³. 3 , which is about 10 times of the latter. The design of this embodiment can better ensure the accurate measurement of the slurry density measuring device.

[0039] The above is only an embodiment of the present invention. The commonly known technical common sense in the scheme is not described in detail here. The ordinary technicians in the relevant field are aware of all the common technical knowledge in the technical field to which the invention belongs before the application date, can obtain all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement this scheme in combination with their own abilities under the enlightenment given by this application. Some typical commonly known technologies should not become obstacles for ordinary technicians in the relevant field to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, they can also make some adjustments and improvements, which should also be regarded as the scope of protection of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection claimed by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A desulfurization absorption tower slurry density measurement system, comprising a slurry inlet channel for connecting to a slurry outlet of an absorption tower (1) and a slurry outflow channel for introducing measured slurry into a pit, an expansion device (2) for receiving slurry from the slurry inlet channel and performing slurry separation, an emptying device (4) located at the top of the expansion device (2) for exhausting gas, and a density measuring device (3) for measuring density, wherein the slurry outlet at the bottom of the expansion device (2) is connected to the density measuring device (3).

2. The desulfurization absorption tower slurry density measurement system according to claim 1 is characterized in that: The total volume of the expansion device (2) is greater than the total volume of the slurry entering the channel, preferably greater than or equal to 10 times.

3. The absorption tower slurry density measurement system according to claim 1 or 2, characterized in that: The top of the density measuring device (3) is connected to the emptying device (4).

4. The desulfurization absorption tower slurry density measurement system according to any one of claims 1 to 3, characterized in that: The bottom slurry outlet of the expansion device (2) is in communication with the bottom of the density measuring device (3).

5. The desulfurization absorption tower slurry density measurement system according to any one of claims 1 to 4, characterized in that: The highest point of the density measuring device (3) is lower than the highest point of the capacity expansion device (2).

6. The desulfurization absorption tower slurry density measurement system according to any one of claims 1 to 5, characterized in that: The slurry outlet is located at the lower part of the absorption tower (1).

7. The desulfurization absorption tower slurry density measurement system according to any one of claims 1 to 6, characterized in that: The position where the slurry inlet channel communicates with the expansion device (2) is located at the upper part of the expansion device (2).

8. The desulfurization absorption tower slurry density measurement system according to any one of claims 1 to 7, characterized in that: The slurry enters the slurry inlet channel from the slurry outlet of the absorption tower (1) by static pressure.

9. The desulfurization absorption tower slurry density measurement system according to any one of claims 1 to 8, characterized in that: It also includes a pH measuring device (7) for measuring the pH value, flow control valves at various locations for controlling the flow of slurry, and flushing water inlets (5) for cleaning various locations.

10. The desulfurization absorption tower slurry density measurement system according to any one of claims 1 to 9, characterized in that: The expansion device (2) has a cylindrical middle portion, and a conical structure with a bottom and a top that respectively tapers downward and upward.

Images