CN113376318A - Method for measuring pH value of slurry in absorption tower for wet flue gas desulfurization - Google Patents
Method for measuring pH value of slurry in absorption tower for wet flue gas desulfurization Download PDFInfo
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- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/48—Sulfur compounds
- B01D53/50—Sulfur oxides
- B01D53/501—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
- B01D53/502—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound characterised by a specific solution or suspension
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Abstract
The invention provides a method for measuring the pH value of slurry in an absorption tower for wet flue gas desulfurization, which comprises the steps of using a measuring device, wherein the measuring device comprises an inlet pipeline, a sampling port switching valve, a pH meter measuring cylinder, outlet regulating valves arranged at the downstream and the lower part of the pH meter measuring cylinder and a pH meter mounting port, the pH meter mounting port is arranged in an inclined state, so that a probe of a pH meter inserted into the pH meter mounting port is inserted downwards in an inclined manner, and the angle formed by the axial lead of the pH meter mounting port and the horizontal plane is 15-65 degrees; the measuring device also comprises a flushing water pipe and a flushing water switch valve which are connected to an inlet pipeline at the downstream of the sampling port switch valve; the inner diameter or equivalent inner diameter of the measuring cylinder of the pH meter is more than 2 times of the inner diameter of the inlet pipeline; the measuring method comprises two steps of measuring the pH value of the slurry and flushing the device. The slurry in all areas in the method and the device is always in a flowing state, so that the sedimentation and the blockage are avoided, and the pH value of the slurry is stably and accurately measured.
Description
Technical Field
The invention belongs to the field of flue gas desulfurization, and particularly relates to a method for measuring the pH value of slurry in an absorption tower for wet flue gas desulfurization.
Background
The invention is mainly applied to the field of limestone (lime) -gypsum wet flue gas desulfurization. Limestone (lime) -gypsum wet desulphurization (WFGD) technology is the mainstream technology of flue gas desulphurization worldwide and has the advantages of mature technology, high desulphurization efficiency, stable operation, wide range of applicable coal types, easy obtainment of absorbent, low price and the like. Is widely applied to flue gas desulfurization of thermal power plants, steel sintering and the like.
In the wet flue gas desulfurization process, slurry in an absorption tower is mainly used for being in countercurrent contact with flue gas to remove SO in the flue gas2Iso-pollutants, utilizing SO2The slurry has the characteristics of good solubility in water and capability of causing chain chemical reaction, and the pH value of the slurry is a key factor for the chain chemical reaction to be continued. pH value mainly to SO2Reaction mass transfer process after absorption, oxidation effect in slurry pool, CaCO3Dissolution, gypsum crystallization and fouling of the absorber are all influential and are the core parameters for normal operation and operation of wet desulphurization.
The measured slurry in the desulfurization system generally contains 12-18 wt% of solid, and has corrosivity and abrasiveness. When measuring the slurry pH, it is common to use a plug-in pH meter. The main measurement modes at present are: 1) the pH meter is inserted into the outlet pipeline of the pump, such as the outlet pipeline of the measuring pump, the outlet pipeline of the gypsum discharge pump, and the like. 2) The pH meter is inserted into a branch pipeline led out from a main pipe at the outlet of the slurry circulating pump, and the like. 3) The gravity flow pipe is led to a trench from the absorption tower, the pipeline is horizontally arranged, and the pH meter is vertically inserted into the gravity flow pipe which is horizontally arranged. 4) A pH meter measuring box is arranged, slurry is led to the lower part (or the bottom) of the measuring box, the slurry overflows from the upper part of the pH meter measuring box and is discharged, and the pH meter is inserted on the pH meter measuring box.
The methods 1) and 2) require a separate metering pump or an increased discharge pump flow, which additionally increases energy consumption. In addition, the pipeline is easy to block when the flow rate is too slow, the pipeline is high in flow rate, the abrasion to the pH meter is large, the service life of the pH meter is influenced, and the two modes are rarely used at present. And 3) in order to ensure that the pH meter is immersed in the slurry, the flow rate of the slurry in the pipeline is high, so that the abrasion to the pH meter is large. The mode of 4) is generally a mode of slurry entering and exiting from the bottom, and the abrasion problem of the pH meter is basically solved because the diameter of the measuring box is large and the flow rate is slow. However, in practical use, it is found that slurry is easily accumulated at the inlet and the emptying port at the bottom of the measuring box, which causes the phenomena of blockage or valve jam, and is more obvious especially under the condition that an operator does not operate according to regulations or the valve fails. This is the case, for example, in patent applications or patents CN200910011665, CN201620269777, CN201710322826 and CN 201720736677.
In addition, patent CN201621331608.3 relates to a pH measuring device of absorption tower, including setting up the pipeline in the absorption tower lower part, the pipeline on be connected with the block valve, the block valve be connected with pH measurement jar through the takeover, be connected with the pH meter on the pH measurement jar, and the bottom of pH measurement jar is connected with the pipeline, the pipeline insert the absorption tower pit. The utility model discloses a thick liquid flows automatically through the pipeline, need not gypsum discharge pump continuous operation, can realize energy saving and consumption reduction's purpose.
However, in actual use, the scheme has the defects that the pH meter cannot be regularly washed, the installation sleeve of the pH meter is easy to block, the total amount of slurry in the pH measuring tank is unstable, the stability and the accuracy of the measurement of the pH meter cannot be ensured, the pH meter cannot normally measure and the like.
And patent CN201821196313.9 discloses a PH detection device for desulfurization, PH detection device for desulfurization includes PH detection device casing, inner tube butterfly valve clack, PH detection device shunt, thick liquid entry structure and washing structure, be provided with the PH detection device inner tube in the PH detection device casing, the outer wall of PH detection device casing is provided with the preformed hole, the inner tube butterfly valve rod is worn to establish thereby the preformed hole will the inner tube butterfly valve clack is fixed in the PH detection device inner tube, the inner tube butterfly valve clack is used for adjusting intraductal thick liquid filtrate flow size, the lower port of PH detection device shunt nestification in the last mouth of pipe of PH detection device casing. The utility model discloses a having adopted can be divided into the thick phase behind impeller and the separation of rotatory filter disc and take grainy thick liquid and thick liquid filtrating with the thick liquid, avoid the PH meter probe of glass bubble extremely to damage, guaranteed the safe and reliable operation of PH meter, PH pricing is expensive, the cost of maintenance that significantly reduces. The utility model discloses a reasonable in design, compact structure easily installs.
However, in practical use, the scheme has the defects that the installation sleeve of the pH meter is easy to block, the total amount of the slurry in the pH measuring tank is unstable, so that the stability and the accuracy of the measurement of the pH meter cannot be ensured, the pH meter cannot normally measure, the running time and the energy consumption of a drainage pump of the absorption tower are increased when the slurry returns to the tower due to excessive discharge of the slurry from the absorption tower, solid particles in gypsum slurry are very fine, so that the scheme can only stay at a theoretical level due to difficult separation, and the like.
Therefore, there is a need in the art to develop a new method and device for measuring the pH of slurry in an absorption tower for wet flue gas desulfurization.
Disclosure of Invention
The invention aims to provide a measuring device and a measuring method for measuring the pH value of slurry of a wet flue gas desulfurization absorption tower, which can effectively solve the problems of abrasion of a pH meter, easy blockage of the device, high operating requirement of the device, low fault tolerance rate, high operating cost and the like, and are simple to operate and capable of being controlled manually or electrically.
The invention firstly provides a method for measuring the pH value of slurry in an absorption tower for wet flue gas desulfurization, the measuring method comprises using a measuring device for measuring the pH value of the slurry in the absorption tower, the measuring device comprises an inlet pipeline, a sampling port switch valve, a pH meter measuring cylinder, an outlet adjusting valve and one or more pH meter mounting ports, wherein the inlet pipeline is used for connecting a slurry sampling port arranged on the side wall of the absorption tower for wet flue gas desulfurization, the sampling port switch valve is arranged on the inlet pipeline, the pH meter measuring cylinder is arranged at the downstream and below of the inlet pipeline and is vertically arranged, the outlet adjusting valve is arranged at the downstream and below of the pH meter measuring cylinder, and the one or more pH meter mounting ports are arranged on the side wall of the pH meter measuring cylinder, the pH meter mounting opening is arranged in an inclined state, so that a probe of the pH meter inserted into the pH meter mounting opening is obliquely and downwards inserted into the slurry of the pH meter measuring cylinder, and the angle formed by the axis of the pH meter mounting opening and the horizontal plane is 15-65 degrees; the measuring device also comprises a flushing water pipe and a flushing water switch valve which are connected to an inlet pipeline on the downstream of the sampling port switch valve, the flushing water switch valve is arranged on the flushing water pipe, and the flushing water pipe and the flushing water switch valve are arranged on the upstream and the upper part of the inlet of the pH meter measuring cylinder; the inner diameter or equivalent inner diameter of the pH meter measuring cylinder is more than 2 times of the inner diameter of the inlet pipeline; the measuring method comprises the following steps of A, measuring the pH value of the slurry: after a sampling port switch valve is opened, slurry flows out of the absorption tower under the action of pressure, flows into a pH meter measuring cylinder inserted with a pH meter through a sampling port and an inlet pipeline, the opening degree of an outlet adjusting valve is controlled to ensure that a pH meter probe is immersed in the slurry in the pH meter measuring cylinder, and the opening degree of the outlet adjusting valve is not too large to ensure that the flow rate in the pH meter measuring cylinder is controlled at a lower level, so that the abrasion of the pH meter is prevented, and the discharge amount of the slurry from the absorption tower can be reduced to the maximum extent; after being measured by a pH meter measuring cylinder 9, the slurry is discharged out of the device from an outlet pipeline; step B, flushing the device: in the flushing process, firstly closing a sampling opening switch valve, adjusting the opening of the outlet regulating valve to be maximum, and emptying the pipeline and the slurry in the pH meter measuring cylinder; then opening a washing water switch valve, washing the pH meter measuring cylinder, closing the washing water switch valve after washing for a period of time, closing an outlet regulating valve, and opening the washing water switch valve to enable inlet pipelines at the downstream of the pH meter measuring cylinder and a sampling port switch valve to be filled with water; closing the flushing water switch valve and opening the outlet regulating valve to empty the water in the pipeline and the pH meter measuring cylinder, and adjusting the flushing time and times according to the field operation condition; after the washing is finished, the outlet regulating valve can be regulated to the specified opening degree, the sampling port switching valve can be opened after the washing water switching valve is closed, and the step A is returned to for the normal measurement of the pH value of the slurry of the wet flue gas desulfurization absorption tower.
In a specific embodiment, the method further comprises pumping the slurry discharged from the outlet pipeline in the step A to the outside of the device back to the absorption tower after accumulation.
In a specific embodiment, step B includes: and opening a flushing water switch valve, flushing the pH meter measuring cylinder, and closing the flushing water switch valve after 5-10 seconds of flushing.
In a specific embodiment, the pH meter measuring cylinder (9) is in a cylindrical shape, the inner diameter of the pH meter measuring cylinder (9) is 2-10 times, preferably 3-5 times that of the inlet pipeline (6), a flange (10) facilitating device maintenance and a reducing section (11) arranged below the flange (10) are further arranged at the bottom of the pH meter measuring cylinder (9), the inner diameter of the upper end of the reducing section (11) is matched with the inner diameter of the pH meter measuring cylinder (9), and the inner diameter of the lower end of the reducing section (11) is matched with the inner diameter of an outlet pipeline (13) providing an installation position for an outlet adjusting valve (12).
In a specific embodiment, the pH meter measuring cylinder (9) is in a cone shape, and the upper end of the pH meter measuring cylinder (9) is large in diameter and the lower end of the pH meter measuring cylinder is small in diameter.
In a specific embodiment, the sampling opening switch valve (3) and the outlet regulating valve (12) are straight-through valves, the slurry flow path in the valves is linear, and the outlet regulating valve (12) is a valve with adjustable valve opening degree and thus adjustable slurry flow.
In a particular embodiment, the measuring device further comprises an inlet screen (1) arranged at the slurry sampling port (2) and within the absorption tower (14).
In a specific embodiment, the pH meter mounting ports are two or more, and a plurality of pH meter mounting ports are provided at different height positions on the pH meter measuring cylinder (9).
In a particular embodiment, the flush water pipe (4) and the flush water switch valve (5) are both arranged above the inlet line (6) so that the slurry in the inlet line (6) does not flow through and clog the flush water switch valve (5).
In a specific embodiment, the angle formed by the axis line of the pH meter mounting opening and the horizontal plane is 30-60 degrees.
The invention also provides a measuring device for measuring the pH value of slurry in the absorption tower, which comprises an inlet pipeline (6) used for connecting a slurry sampling port (2) arranged on the side wall of the absorption tower for wet flue gas desulfurization, a sampling port switch valve (3) arranged on the inlet pipeline (6), a pH meter measuring cylinder (9) which is arranged at the downstream and below of the inlet pipeline (6) and is vertically arranged, an outlet regulating valve (12) arranged at the downstream and below of the pH meter measuring cylinder (9), and one or more pH meter mounting ports arranged on the side wall of the pH meter measuring cylinder (9), the pH meter mounting port is arranged in an inclined state, so that a probe of the pH meter inserted into the pH meter mounting port is obliquely and downwards inserted into the slurry of the pH meter measuring cylinder (9), and the angle formed by the axis line of the pH meter mounting port and the horizontal plane is 15-65 degrees; the measuring device further comprises a flushing water pipe (4) and a flushing water switch valve (5) which are connected to an inlet pipeline (6) on the downstream of the sampling port switch valve (3), the flushing water switch valve (5) is arranged on the flushing water pipe (4), and the flushing water pipe (4) and the flushing water switch valve (5) are arranged on the upstream and the upper side of the inlet of the pH meter measuring cylinder (9); the inner diameter or equivalent inner diameter of the pH meter measuring cylinder (9) is more than 2 times of the inner diameter of the inlet pipeline (6).
The main advantages of the device and the method are as follows:
1) the whole device comprises a pipeline without dead zones, and slurry in all the areas in the device is in a flowing state all the time and is not deposited. The outlet regulating valve 12 is a straight-through valve and always keeps a certain opening degree when the pH value measuring device is normally used, and even if an operator does not operate after the sampling port switch valve 3 is closed, slurry can be automatically discharged from the bottom of the outlet regulating valve 12, the slurry cannot block the bottom of the device, the operation flow is simplified to the maximum extent, and the fault tolerance of operation is improved.
2) Simple process flow, low cost and convenient installation and operation. The key position sets up flange joint, can conveniently overhaul.
3) In the invention, the pH meter is inserted in a side way, in particular, the pH meter is inserted into the slurry in an inclined downward way, and the installation port 8 of the pH meter keeps a certain inclination angle so as to effectively prevent the slurry from depositing and blocking the position.
4) 2 entrances of sample connection set up filter screen 1, can prevent effectively that great solid from getting into pH meter measuring cylinder 9, and then avoid causing the damage and blockking up pH meter measuring cylinder to the pH meter.
5) The diameter of the vertically or obliquely arranged pH meter measuring cylinder 9 is obviously larger than that of the inlet pipeline 6 for sampling, and the flow of the slurry is controlled by matching the opening of the outlet regulating valve 12, so that the flow rate of the slurry in the pH meter measuring cylinder 9 can be ensured to be very low, and the condition of scouring and abrasion on a probe of the pH meter can not occur.
6) The flushing water pipe 4 is connected from the inlet pipeline 6, the flushing water pipe 4 is located above the top of the pH meter measuring cylinder 9, preferably, the flushing water pipe 4 and the flushing water switch valve 5 are both arranged above the inlet pipeline 6, flowing slurry is located below the flushing water switch valve 5, and the flushing water switch valve 5 cannot be normally opened due to deposition of the slurry.
7) The outlet regulating valve 12 at the lower part is a straight-through valve which can regulate the flow of the slurry by regulating the opening degree, can ensure that the measuring cylinder 9 of the pH meter is filled with the slurry to be measured, and can control the flow rate of the slurry in the measuring cylinder of the pH meter. Thereby ensuring that the pH value is measured accurately and the slurry does not cause serious scouring to the pH meter.
In addition, compared with patent CN201621331608.3, the invention has the following characteristics: 1) the invention is provided with the flushing water pipe which can flush the pH meter at regular time. 2) The pH meter is obliquely inserted into the slurry in the pH meter measuring cylinder, and is not horizontally inserted or vertically inserted, so that solid impurities are not easily accumulated at the position of the pH meter mounting sleeve (namely at the position of a pH meter mounting opening), and meanwhile, the probe can be fully contacted with the slurry in the pH meter measuring cylinder. 3) According to the invention, the outlet regulating valves are arranged at the downstream and the lower part of the pH meter measuring cylinder, and the inner diameter of the pH meter measuring cylinder is obviously larger than the inner diameter of the pipeline, so that the pH meter measuring cylinder can ensure that the slurry in the pH meter measuring cylinder is full of the pipeline and the flow rate of the slurry in the pH meter measuring cylinder is slow, and therefore, the pH meter measuring device can ensure the stability and the accuracy of the pH meter measurement and ensure the normal measurement of the pH meter. It is not feasible in practice to provide the outlet regulating valve in this position. The reason is that: if the flow of the pulping liquid is controlled by an inlet valve positioned at the upstream of a measuring cylinder of the pH meter (the opening degree of the valve is reduced), the diameter of the measuring cylinder is larger than that of a pipeline and is vertically installed, the pulp in the measuring cylinder is not full, the stability and the accuracy of the measurement of the pH meter cannot be ensured, and the abnormal measurement can be caused. If the opening of an inlet valve positioned at the upstream of the pH meter measuring cylinder is large, a large amount of slurry flows out of the absorption tower due to the water column pressure of about 7-11 m in the general absorption tower, and the slurry in the measuring cylinder can not be measured in a full pipe in the case; and the slurry outflow is too large, so that the slurry returns to the absorption tower, and the running time and the energy consumption of a drainage pump of the absorption tower are increased. In summary, the present invention integrally solves all the problems of the prior art by providing a flush water pipe and flush water on-off valve, an obliquely disposed pH meter mounting port, a pH meter measuring cylinder having an inner diameter significantly greater than the inner diameter of the pipe, and outlet regulating valves disposed downstream and below the pH meter measuring cylinder.
Compared with patent CN201821196313.9, the invention has the following characteristics: 1) according to the invention, the pH meter is obliquely inserted into the slurry in the pH meter measuring cylinder instead of horizontally inserted, so that solid impurities are not easy to accumulate at the position of the pH meter mounting sleeve (namely at the position of the pH meter mounting opening), and meanwhile, the probe can be fully contacted with the slurry in the pH meter measuring cylinder. 2) As described in the above paragraph 3, in the present invention, the outlet regulating valves are disposed at the downstream and the lower part of the pH meter measuring cylinder, and the inner diameter of the pH meter measuring cylinder is significantly larger than the inner diameter of the pipeline, so that the present invention can ensure the stability and accuracy of the pH meter measurement and ensure the normal measurement of the pH meter. 3) The solution of the patent is to reduce the abrasion of the pH meter by separating the slurry into a clear liquid and a concentrated liquid and measuring the clear liquid by using the pH meter. The invention reduces the abrasion of the slurry to the pH meter by arranging the pH meter measuring cylinder which is larger than the pipe diameter of the inlet pipeline, the outlet regulating valves which are arranged at the downstream and the lower part of the pH meter measuring cylinder and controlling the opening of the valves to control the flow of the slurry. The solution of the present invention is feasible and the solution of the patent can only stay in theoretical stage because the solid particles in the gypsum slurry in the absorption tower are very fine (for example, the measured data shows that the particle size distribution of the suspended substance of gypsum particles and limestone particles in the slurry is 0.76% of solid particles smaller than 0.83 microns, 15.84% of solid particles smaller than 9.38 microns, 37.35% of solid particles smaller than 26.5 microns, 66.36% of solid particles smaller than 53 microns, 84.14% of solid particles smaller than 75 microns and 99.87% of solid particles smaller than 150 microns), so that the general separation method is difficult to separate, and the specific separation scheme is not specified in the patent. Therefore, the scheme can only stay on a theoretical level, can not realize the separation purpose in practice, is easy to block, and has no application value in the flue gas desulfurization engineering. 4) According to the invention, the outlet regulating valves arranged at the downstream and below the pH meter measuring cylinder can accurately control the flow of the slurry entering the pH meter measuring cylinder, so that the excessive discharge of the slurry from the absorption tower cannot be caused, and the increase of the running time and the energy consumption of the drainage pump of the absorption tower cannot be caused when the slurry returns to the tower.
Drawings
FIG. 1 is a schematic view of a measuring apparatus for measuring the pH of a slurry in an absorption tower according to the present invention.
In the figure: 1. an inlet screen; 2. a sampling port; 3. a sampling port switch valve; 4. flushing the water pipe; 5. a flush water on-off valve; 6. an inlet line; 7. a first pH meter mounting port; 8, a second pH meter mounting port; 9. a pH meter measuring cylinder; 10. a flange; 11. a diameter-changing section; 12. an outlet regulating valve; 13. an outlet line; 14. an absorption tower.
Detailed Description
The working process of the measuring device comprises the following steps: during normal operation, the absorption tower slurry tank is filled with slurry and has a higher liquid level, and the sampling port 2 is generally positioned at the lower part of the slurry tank, so that the sampling port 2 has certain static pressure. After the sampling port switch valve 3 is opened, the slurry flows out of the absorption tower 14 under the action of pressure, flows into the pH meter measuring cylinder 9 inserted with the pH meter through the sampling port 2 and the inlet pipeline 6, and is ensured to be filled with the slurry by controlling the opening of the outlet adjusting valve 12, so that the probe of the pH meter is ensured to be immersed in the slurry. Meanwhile, the valve opening of the outlet regulating valve 12 should not be too large to ensure that the flow rate in the measuring cylinder of the pH meter is controlled at a lower level, so as to prevent the pH meter from being worn. The slurry is measured by a pH meter measuring cylinder 9, discharged from an outlet pipe 13 into a trench, collected in a pit, and finally returned to the absorption tower 14 by a pump. pH meters typically require regular flushing during operation. In the flushing process, the sampling opening switching valve 3 is closed firstly, the opening degree of the outlet adjusting valve 12 is adjusted to be maximum, and the pipeline and the slurry in the pH meter measuring cylinder 9 are emptied. And finally, washing the measuring cylinder of the pH meter. In the washing process, the washing water switch valve 5 is opened firstly, the pH meter measuring cylinder 9 is washed, the washing water switch valve 5 is closed after 5-10 seconds of washing, the outlet adjusting valve 12 is closed, the washing water switch valve 5 is opened to enable the inlet pipeline 6 at the downstream of the pH meter measuring cylinder 9 and the sampling port switch valve 3 to be full of water, the washing water switch valve 5 is closed, the outlet adjusting valve 12 is opened to empty the water in the pH meter measuring cylinder 9, and the washing time and the washing frequency are adjusted according to the field operation condition. After the washing is finished, the outlet regulating valve 12 can be regulated to a specified opening degree, the sampling port switch valve 3 can be opened after the washing water switch valve 5 is closed, and the normal measurement of the pH value of the slurry of the wet flue gas desulfurization absorption tower is carried out.
Furthermore, the device can be operated both manually and electrically (pneumatically). Because the device has no easy-to-block point, the operation requirement is lower than that of other schemes in the prior art. The sampling port opening/closing valve 3, the outlet regulating valve 12, and the wash water opening/closing valve 5 may all be provided as manual valves. When the device needs to be flushed, the device is operated on site by an operator. This scheme also can set up sample connection ooff valve 3, export adjusting valve 12, washing water ooff valve 5 all into motorised valve (pneumatic valve), brings DCS (PLC) control system into, realizes full automatic operation, need not operating personnel operation.
The sampling opening switch valve 3 and the outlet regulating valve 12 in the device both adopt straight-through valves, namely, the flow path of the slurry in the valve is linear, so that the slurry can be effectively prevented from being blocked and the emptying is facilitated. The outlet regulating valve 12 is a valve with adjustable flow, and the sampling opening switch valve 3 and the flushing water switch valve 5 can both use a regulating valve with adjustable flow or use a valve with non-adjustable flow.
In the present invention, the number of pH meter mounting ports provided on the pH meter measuring cylinder 9 and the number of corresponding pH meters may be 1, 2, 3, etc., and may be specifically determined according to the measurement requirements of the project. If the pH meter installing port and the pH meter are both set to be 1, no standby data and no comparison are available for measuring the pH value of the slurry, and the operation safety is insufficient. It is generally recommended that the number of the pH meter mounting ports and the corresponding number of the pH meters be 2 or more, and it is preferable that the pH meter mounting ports be provided at different height positions on the pH meter measuring cylinder 9. The length of the pH meter measuring cylinder 9 can be increased or shortened according to the number of the pH meters.
The outlet line 13 in fig. 1 comprises two 90 ° bends, which are not a requirement of the present invention. Depending on the field conditions, the outlet line 13 of the pH meter measuring cylinder may be inserted vertically directly into a drain or into a container holding the slurry.
In the present invention, the material of the pH measuring cylinder 9 may be carbon steel lining rubber, an alloy material, a non-metal material (such as glass fiber reinforced plastic), and the pH measuring cylinder 9 is not limited to a certain material. According to actual conditions, different suitable materials can be selected to manufacture the pH meter measuring cylinder.
In the present invention, if the pH meter measuring cylinder 9 is configured to be cylindrical, the lower tapered section 11 is an essential component, which can effectively ensure that the solid in the slurry can be smoothly guided into the outlet pipe 13 and discharged under the condition that the flow rate of the slurry is slow.
Under the conditions of considering practicability, manufacturing cost and the like, the pipe diameters of the measuring sampling port 2, the inlet pipeline 6 and the outlet pipeline 13 are generally DN 40-DN 65, and the diameter of the pH meter measuring cylinder 9 is DN 150-DN 300.
In the present invention, the installation angle of the pH meter is generally such that the installation opening of the pH meter is inclined upward by 30 to 60 degrees, that is, the insertion direction line of the pH meter forms an angle of 30 to 60 degrees with the horizontal plane, and the pH meter is inserted in such a manner that the probe is inserted obliquely downward into the slurry in the measuring cylinder 9 of the pH meter. The pH meter mounting opening is inclined upward by 45 degrees in consideration of the use effect and the aesthetic appearance.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions and substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.
Claims (10)
1. A method for measuring the pH value of slurry in an absorption tower for wet flue gas desulfurization, which comprises using a measuring apparatus for measuring the pH value of slurry in an absorption tower, the measuring apparatus comprising an inlet pipe (6) for connecting a slurry sampling port (2) provided on the side wall of the absorption tower for wet flue gas desulfurization, a sampling port switching valve (3) provided on the inlet pipe (6), a pH meter measuring cylinder (9) provided downstream and below the inlet pipe (6) and vertically provided, an outlet regulating valve (12) provided downstream and below the pH meter measuring cylinder (9), and one or more pH meter mounting ports provided on the side wall of the pH meter measuring cylinder (9) and arranged in an inclined state such that a pH meter probe inserted therein is inserted obliquely downward into the slurry in the pH meter measuring cylinder (9), the angle formed by the axis line of the pH meter mounting opening and the horizontal plane is 15-65 degrees; the measuring device further comprises a flushing water pipe (4) and a flushing water switch valve (5) which are connected to an inlet pipeline (6) on the downstream of the sampling port switch valve (3), the flushing water switch valve (5) is arranged on the flushing water pipe (4), and the flushing water pipe (4) and the flushing water switch valve (5) are arranged on the upstream and the upper side of the inlet of the pH meter measuring cylinder (9); the inner diameter or equivalent inner diameter of the pH meter measuring cylinder (9) is more than 2 times of the inner diameter of the inlet pipeline (6);
the measuring method comprises the following steps of,
step A, measuring the pH value of the slurry: after a sampling port switch valve is opened, slurry flows out of the absorption tower under the action of pressure, flows into a pH meter measuring cylinder inserted with a pH meter through a sampling port and an inlet pipeline, the opening degree of an outlet adjusting valve is controlled to ensure that a pH meter probe is immersed in the slurry in the pH meter measuring cylinder, and the opening degree of the outlet adjusting valve is not too large to ensure that the flow rate in the pH meter measuring cylinder is controlled at a lower level, so that the abrasion of the pH meter is prevented, and the discharge amount of the slurry from the absorption tower can be reduced to the maximum extent; after being measured by a pH meter measuring cylinder 9, the slurry is discharged out of the device from an outlet pipeline;
step B, flushing the device: in the flushing process, firstly closing a sampling opening switch valve, adjusting the opening of the outlet regulating valve to be maximum, and emptying the pipeline and the slurry in the pH meter measuring cylinder; then opening a washing water switch valve, washing the pH meter measuring cylinder, closing the washing water switch valve after washing for a period of time, closing an outlet regulating valve, and opening the washing water switch valve to enable inlet pipelines at the downstream of the pH meter measuring cylinder and a sampling port switch valve to be filled with water; closing the flushing water switch valve and opening the outlet regulating valve to empty the water in the pipeline and the pH meter measuring cylinder, and adjusting the flushing time and times according to the field operation condition; after the washing is finished, the outlet regulating valve can be regulated to the specified opening degree, the sampling port switching valve can be opened after the washing water switching valve is closed, and the step A is returned to for the normal measurement of the pH value of the slurry of the wet flue gas desulfurization absorption tower.
2. The method according to claim 1, wherein the method further comprises pumping the slurry discharged from the outlet pipeline to the outside of the apparatus in step A back to the absorption tower after accumulation.
3. The measurement method according to claim 1, wherein step B comprises: and opening a flushing water switch valve, flushing the pH meter measuring cylinder, and closing the flushing water switch valve after 5-10 seconds of flushing.
4. The measuring method according to claim 1, wherein the pH meter measuring cylinder (9) is cylindrical, and the inner diameter of the pH meter measuring cylinder (9) is 2 to 10 times, preferably 3 to 5 times, the inner diameter of the inlet pipeline (6), a flange (10) for facilitating device maintenance and a reducer section (11) arranged below the flange (10) are further arranged at the bottom of the pH meter measuring cylinder (9), the inner diameter of the upper end of the reducer section (11) is matched with the inner diameter of the pH meter measuring cylinder (9), and the inner diameter of the lower end of the reducer section (11) is matched with the inner diameter of an outlet pipeline (13) for providing an installation position for the outlet regulating valve (12).
5. The method according to claim 1, wherein the pH meter measuring cylinder (9) has a conical cylinder shape, and the upper end of the pH meter measuring cylinder (9) has a large diameter and the lower end has a small diameter.
6. The method according to claim 1, wherein the sampling port opening/closing valve (3) and the outlet regulating valve (12) are straight-through valves in which the flow path of the slurry in the valve is linear, and the outlet regulating valve (12) is a valve whose opening degree is adjustable so that the flow rate of the slurry is adjustable.
7. The measuring method according to claim 1, characterized in that the measuring device further comprises an inlet screen (1) arranged at the slurry sampling port (2) and inside the absorption tower (14).
8. The method according to any one of claims 1 to 7, wherein the number of the pH meter mounting ports is two or more, and a plurality of the pH meter mounting ports are provided at different height positions on the pH meter measuring cylinder (9).
9. Measuring method according to any of claims 1-7, characterized in that the flushing water pipe (4) and the flushing water switch valve (5) are both arranged above the inlet pipe (6) so that the slurry in the inlet pipe (6) does not flow through and block the flushing water switch valve (5).
10. The method of claim 1, wherein the angle between the axis of the pH meter mounting port and the horizontal plane is 30 to 60 °.
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