A demister performance evaluation system and method for a flue gas seawater desulfurization device

Abstract

The present invention discloses a demister performance evaluation system and method for a flue gas and seawater desulfurization device, comprising a droplet sampler, a steam-water separator, a gas flow meter and an exhaust pump; the droplet sampler extends into a flue, and an inlet of the droplet sampler faces the flow direction of the flue gas, an outlet of the droplet sampler is connected to an inlet of the steam-water separator, an outlet of the steam-water separator is connected to an inlet of a flow regulating valve, an outlet of the flow regulating valve is connected to an inlet of the gas flow meter, a pressure gauge and a thermometer are provided at the inlet of the gas flow meter, and an outlet of the gas flow meter is connected to an inlet of the exhaust pump. The system and method can evaluate the demister performance of the flue gas and seawater desulfurization device.

Description

Technical Field

[0001] The invention belongs to the technical field of pollutant control and relates to a demister performance evaluation system and method for a flue gas seawater desulfurization device. Background Art

[0002] At present, limestone-gypsum wet flue gas desulfurization technology is the most widely used desulfurization technology in the waste gas treatment process. It can meet the requirements of different SO2 emission standards, and is economically feasible and reliable. The evaluation method for the performance of related equipment of wet desulfurization equipment is also quite complete and mature. When the flue gas passes through the wet desulfurization absorption tower, it will carry a large amount of slurry droplets. The particle size of these droplets ranges from a few microns to a few millimeters. It is necessary to use a demister installed at the top of the absorption tower or the tail flue to separate the droplets carried in the flue gas as much as possible. When the performance of the demister is not up to standard, the flue gas carries too many droplets and it will cause "gypsum rain" from the chimney. For the flue gas seawater desulfurization device, a demister is also installed on the upper part of the desulfurization tower or the flue after the desulfurization tower to separate the droplets carried in the flue gas. When the performance of the demister is not up to standard, the flue gas carries too many droplets. The main component of the droplets is seawater with a high salt content, which will cause corrosion of equipment around the chimney. Therefore, the control of the droplet content after the demister is equally important. In the past, the droplet content at the outlet of the demister after the desulfurization absorption tower was generally required to be less than 75 mg / m 3 After the implementation of ultra-low emission, the general standard requires that the droplet content at the demister outlet is less than 20mg / m 3 Therefore, the droplet content in the flue gas at the outlet of the demister has received increasing attention. The performance evaluation method of the demister in the limestone wet flue gas desulfurization system has been relatively mature. Although the flue gas seawater desulfurization system is relatively less used, the droplet content is also important. Therefore, it is urgent to study a more accurate and applicable demister performance test method.

[0003] At present, there are mainly the following methods for testing the performance of demisters in my country: the "weighing method" or "water balance method" used in laboratory demister performance research, the magnesium ion tracer method in GB / T21508 "Performance Test Methods for Coal-fired Flue Gas Desulfurization Equipment" and the magnesium oxide diaphragm impact method used in the on-site limestone wet desulfurization system demister performance evaluation. However, these test methods are not applicable to flue gas seawater desulfurization systems. The "weighing method" cannot measure the amount of water in the flue gas at the inlet of the demister and the weight of the water intercepted by the demister, so it cannot be applied to on-site testing. The magnesium ion tracer method uses the characteristics of the slurry in the limestone wet desulfurization to measure and is not applicable to the seawater desulfurization system. The magnesium oxide diaphragm impact method can be used in the seawater desulfurization system, but it requires a relatively close distance to the demister and is applicable under the condition that water vapor condensation has not yet occurred, which is not available on most sites. Therefore, the existing technology lacks a way to evaluate the performance of demisters in flue gas seawater desulfurization devices. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and to provide a demister performance evaluation system and method for a flue gas seawater desulfurization device. The system and method can evaluate the demister performance of a flue gas seawater desulfurization device.

[0005] To achieve the above-mentioned purpose, the performance evaluation system of the demister of the flue gas and seawater desulfurization device described in the present invention includes a droplet sampler, a steam-water separator, a gas flow meter and a vacuum pump; the droplet sampler extends into the flue, and the inlet of the droplet sampler faces the flow direction of the flue gas, the outlet of the droplet sampler is connected with the inlet of the steam-water separator, the outlet of the steam-water separator is connected with the inlet of the flow regulating valve, the outlet of the flow regulating valve is connected with the inlet of the gas flow meter, wherein a pressure gauge and a thermometer are provided at the inlet of the gas flow meter, and the outlet of the gas flow meter is connected with the inlet of the vacuum pump.

[0006] The outlet of the droplet sampler is connected with the inlet of the steam-water separator through a sample gas pipeline.

[0007] The performance evaluation method of the flue gas seawater desulfurization device demister of the present invention comprises the following steps:

[0008] 1) Divide the measurement section of the demister outlet flue into a grid structure with equal cross sections;

[0009] 2) Use the Pitot tube to measure the flue gas velocity distribution at several representative points in the equal-section grid structure, and use this to calculate the average flue gas velocity V of the entire demister outlet flue measurement section s , and select representative points for droplet content testing;

[0010] 3) Determine the extraction rate of flue gas during droplet sampling

[0011] 4) Pre-processing the droplet sampler;

[0012] 5) Calculate the flue gas flow rate Q sampled by the droplet sampler cy ;

[0013] 6) While the droplet sampler is sampling, the seawater at the outlet of the flue gas seawater desulfurization device is sampled;

[0014] 7) According to the flue gas flow Q sampled by the droplet sampler cy Determine the total mass concentration C of droplets carried in the smoke drop ;

[0015] 8) Analyze the concentration of NaCl in the rinse fluid of the droplet sampler C NaCl-CX and the NaCl concentration C in the seawater sampled during the experiment NaCl-FGD , and then according to the concentration of NaCl in the flushing liquid of the droplet sampler, C NaCl-CX, the concentration of NaCl in seawater sampled during the experiment C NaCl-FGD and the total mass concentration of droplets carried in the smoke C drop Calculate the mass concentration C of droplets in flue gas after correcting the effect of water vapor condensation mid-drop ;

[0016] 9) According to the standard oxygen concentration in flue gas in the pollutant emission standard and the actual oxygen content in flue gas, the mass concentration of droplets in flue gas after correcting the effect of water vapor condensation C mid-drop The mass concentration of droplets in the flue gas after conversion to standard oxygen content C cr-drop ;

[0017] 10) According to the mass concentration of droplets in the flue gas after conversion to the standard oxygen content C cr-drop Evaluating the performance of mist eliminators in a flue gas seawater desulfurization plant.

[0018] The specific operations of step 1) are:

[0019] According to GB / T 16157, the measurement section of the demister outlet flue is divided into a grid structure with equal cross-sections.

[0020] Smoke extraction rate during droplet sampling for:

[0021]

[0022] Where: D cy is the sampling nozzle diameter of the droplet sampler.

[0023] The specific operations of step 4) are:

[0024] The droplet sampler was cleaned with deionized water and dried at 105°C for 2 h. After drying, the droplet sampler was placed in a drying dish to cool for 30 min.

[0025] The specific operations of step 5) are:

[0026] Insert the droplet sampler into the representative point selected in the measurement section of the demister outlet flue, and adjust the flow regulating valve to make the suction rate of the vacuum pump The sampling duration is 30min-60min. The starting flow rate Q measured by the gas flow meter is recorded when the droplet sampler is sampling. st and end flow Q end , the pressure P measured by the pressure gauge S , the temperature T measured by the thermometer S , and the oxygen content in the dial flue gas O S ;

[0027] The flue gas flow rate Q sampled by the droplet sampler is cy for:

[0028]

[0029] The specific operation process of step 7) is:

[0030] After sampling, the outer surface of the droplet sampler is cleaned and wiped clean with deionized water, and then the droplet sampler is weighed to obtain the weight M of the droplet sampler after sampling. cy The inner wall of the droplet sampler is fully rinsed with deionized water, and the rinse liquid is collected in a volumetric flask and then fixed to volume. The cleaned droplet sampler is placed at 105°C for 2 hours to dry, and the dried droplet sampler is placed in a drying dish to cool for 30 minutes and then weighed to obtain the weight M. cx ;

[0031] The total mass concentration of droplets carried in the smoke is C drop for:

[0032]

[0033] The mass concentration of droplets in the flue gas after correcting the effect of water vapor condensation C mid-drop for:

[0034]

[0035] Among them, V CX is the volume of the droplet sampler flushing water after sampling, ρ sea is the density of seawater at the outlet of the desulfurization tower.

[0036] The mass concentration of droplets in the flue gas after conversion to standard oxygen content C cr-drop for:

[0037]

[0038] Among them, O cr The standard oxygen content specified in the emission standard, O s is the actual oxygen content in the flue gas.

[0039] The present invention has the following beneficial effects:

[0040] In the specific operation of the demister performance evaluation system and method for the flue gas and seawater desulfurization device described in the present invention, the measurement section of the flue duct at the demister outlet is divided into an equal-section grid structure, and representative points are selected in the equal-section grid structure, and a droplet sampler is placed at the representative point. The flue gas passes through the droplet collector by constant speed sampling, and droplets in the flue gas larger than a certain particle size are captured by the droplet sampler under the action of centrifugal force. After sampling, the droplet sampler is weighed, and the droplet content carried by the flue gas after the demister is calculated according to the weight change of the droplet sampler and the salt content of the captured droplets. The demister performance of the flue gas and seawater desulfurization device is evaluated based on this, and the influence of condensed water in the flue gas on the droplet content test result is effectively avoided. The droplet content can also be accurately measured for the flue section whose measurement section is far from the demister outlet. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the structure of the present invention.

[0042] Among them, 1 is a droplet sampler, 2 is a steam-water separator, 3 is a flow regulating valve, 4 is a pressure gauge, 5 is a temperature gauge, 6 is a gas flow meter, and 7 is a vacuum pump. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only an embodiment of a part of the present invention, not all embodiments, and is not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concepts disclosed in the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0044] The accompanying drawings show schematic diagrams of structures according to embodiments disclosed in the present invention. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0045] refer to Figure 1The performance evaluation system of the flue gas and seawater desulfurization device demister of the present invention comprises a droplet sampler 1, a steam-water separator 2, a gas flow meter 6 and an exhaust pump 7; the droplet sampler 1 extends into the flue, and the inlet of the droplet sampler 1 faces the flow direction of the flue gas, the outlet of the droplet sampler 1 is connected with the inlet of the steam-water separator 2 through the sample gas pipeline, the outlet of the steam-water separator 2 is connected with the inlet of the flow regulating valve 3, the outlet of the flow regulating valve 3 is connected with the inlet of the gas flow meter 6, wherein a pressure gauge 4 and a thermometer 5 are provided at the inlet of the gas flow meter 6, and the outlet of the gas flow meter 6 is connected with the inlet of the exhaust pump 7.

[0046] The specific implementation process of the present invention is:

[0047] 1) Divide the measurement section of the demister outlet flue into a grid structure with equal cross-sections according to GB / T 16157;

[0048] 2) Use the Pitot tube to measure the flue gas velocity distribution at several representative points in the equal-section grid structure, and use this to calculate the average flue gas velocity V of the entire demister outlet flue measurement section s , and select representative points for droplet content testing;

[0049] 3) Determine the extraction rate of flue gas during droplet sampling

[0050] Among them, the droplet sampling pumping rate for:

[0051]

[0052] Where: D cy is the sampling nozzle diameter of the droplet sampler 1.

[0053] 4) Clean the droplet sampler 1 with deionized water, and then dry it at 105° C. for 2 h. After drying, place the droplet sampler 1 in a drying dish to cool for 30 min.

[0054] 5) Insert the droplet sampler 1 into the representative point selected in the measurement section of the demister outlet flue, and adjust the flow control valve 3 so that the suction rate of the suction pump 7 is The sampling duration is 30min-60min, wherein the number of droplet samplers 1 is three, and the starting flow rate Q measured by the gas flow meter 6 is recorded when each droplet sampler 1 performs sample sampling. st and end flow Q end , the pressure P measured by pressure gauge 4 S , the temperature T measured by the temperature table 5 S , and the oxygen content in the dial flue gas O S ;

[0055] The flue gas flow rate Q sampled by droplet sampler 1 is obtained cy for:

[0056]

[0057] 6) While the droplet sampler 1 is sampling, the seawater at the outlet of the flue gas seawater desulfurization device is sampled;

[0058] 7) After sampling, the outer surface of the droplet sampler 1 is cleaned and wiped clean with deionized water, and then the droplet sampler 1 is weighed to obtain the weight M of the droplet sampler 1 after sampling. cy The inner wall of the droplet sampler 1 is fully rinsed with deionized water, and the rinse liquid is collected in a volumetric flask and then fixed to volume. The cleaned droplet sampler 1 is placed at 105°C for 2 hours to dry, and the dried droplet sampler 1 is placed in a drying dish for 30 minutes to cool and then weighed to obtain a weight M. cx ;

[0059] The total mass concentration of droplets carried in the smoke is C drop for:

[0060]

[0061] 8) Analyze the concentration C of NaCl in the flushing liquid of the droplet sampler 1 NaCl-CX and the NaCl concentration C in the seawater sampled during the experiment NaCl-FGD ;

[0062] The mass concentration of droplets in the flue gas after correcting the effect of water vapor condensation is C mid-drop for:

[0063]

[0064] Among them, V CX is the volume of the droplet sampler 1 flushing water after sampling, ρ sea is the density of seawater at the outlet of the desulfurization tower.

[0065] 9) According to the standard oxygen concentration in flue gas in the pollutant emission standard and the actual oxygen content in the flue gas, the droplet concentration is converted to the droplet concentration under standard conditions;

[0066] The mass concentration of droplets in the flue gas after conversion to standard oxygen content C cr-drop for:

[0067]

[0068] Among them, O cr The standard oxygen content specified in the emission standard, O s is the actual oxygen content in the flue gas;

[0069] 10) According to the mass concentration of droplets in the flue gas after conversion to the standard oxygen content C cr-drop Evaluating the performance of mist eliminators in a flue gas seawater desulfurization plant.

[0070] According to the characteristics of the flue gas seawater desulfurization system, the present invention overcomes the shortcomings that the existing demister outlet droplet test method is not suitable for the flue gas seawater dehydration device or the test result cannot represent the actual demister performance because the test section is far away from the demister outlet section, and effectively evaluates the performance of the demister of the flue gas seawater desulfurization device.

Claims

1. A method for evaluating the performance of a demister in a flue gas seawater desulfurization device, characterized in that: A performance evaluation system for a demister of a flue gas and seawater desulfurization device, the performance evaluation system for a demister of a flue gas and seawater desulfurization device comprising a droplet sampler (1), a steam-water separator (2), a gas flow meter (6) and an air pump (7); the droplet sampler (1) extends into the flue, and the inlet of the droplet sampler (1) faces the flow direction of the flue gas, the outlet of the droplet sampler (1) is connected to the inlet of the steam-water separator (2), the outlet of the steam-water separator (2) is connected to the inlet of a flow control valve (3), the outlet of the flow control valve (3) is connected to the inlet of the gas flow meter (6), wherein a pressure gauge (4) and a temperature gauge (5) are provided at the inlet of the gas flow meter (6), and the outlet of the gas flow meter (6) is connected to the inlet of the air pump (7); the outlet of the droplet sampler (1) is connected to the inlet of the steam-water separator (2) through a sample gas pipeline; The following steps are involved: 1) Divide the measurement section of the demister outlet flue into a grid structure with equal cross sections; 2) Use the Pitot tube to measure the flue gas velocity distribution at several representative points in the equal-section grid structure, and use this to calculate the average flue gas velocity V of the entire demister outlet flue measurement section s , and select representative points for droplet content testing; 3) Determine the extraction rate of flue gas during droplet sampling 4) pre-treating the droplet sampler (1); 5) Calculate the flue gas flow rate Q sampled by the droplet sampler (1) cy ; 6) The droplet sampler (1) samples the seawater at the outlet of the flue gas seawater desulfurization device at the same time; 7) According to the flue gas flow Q sampled by the droplet sampler (1) cy Determine the total mass concentration C of droplets carried in the smoke drop ; 8) Analyze the concentration of NaCl in the flushing liquid of the droplet sampler (1) NaCl-CX and the NaCl concentration C in the seawater sampled during the experiment NaCl-FGD , and then according to the concentration C of NaCl in the flushing liquid of the droplet sampler (1) NaCl-CX , the concentration of NaCl in seawater sampled during the experiment C NaCl-FGD and the total mass concentration of droplets carried in the smoke C drop Calculate the mass concentration C of droplets in flue gas after correcting the effect of water vapor condensation mid-drop ; 9) According to the standard oxygen concentration in flue gas in the pollutant emission standard and the actual oxygen content in flue gas, the mass concentration of droplets in flue gas after correcting the effect of water vapor condensation C mid-drop The mass concentration of droplets in the flue gas after conversion to standard oxygen content C cr-drop ; 10) According to the mass concentration of droplets in the flue gas after conversion to the standard oxygen content C cr-drop Evaluate the performance of mist eliminators in flue gas seawater desulfurization plants; Smoke extraction rate during droplet sampling for: Where: D cy is the sampling nozzle diameter of the droplet sampler (1); The specific operations of step 5) are: The droplet sampler (1) is inserted into the representative point selected in the measurement section of the flue gas duct at the demister outlet, and the flow regulating valve (3) is adjusted so that the suction rate of the suction pump (7) is The sampling duration is 30 minutes to 60 minutes. The starting flow rate Q measured by the gas flow meter (6) when the droplet sampler (1) is sampling is recorded. st and end flow Q end , the pressure P measured by the pressure gauge (4) S , the temperature T measured by the temperature table (5) S ; The flue gas flow rate Q sampled by the droplet sampler (1) is cy for: Among them, P0 is the standard atmospheric pressure; The specific operation process of step 7) is: After sampling, the outer surface of the droplet sampler (1) is cleaned and wiped clean with deionized water, and then the droplet sampler (1) is weighed to obtain the weight M of the droplet sampler (1) after sampling. cy , the inner wall of the droplet sampler (1) is fully rinsed with deionized water, and the rinse liquid is collected in a volumetric flask and then fixed to volume, the cleaned droplet sampler (1) is placed at 105°C for drying for 2 hours, and the dried droplet sampler (1) is placed in a drying dish for cooling for 30 minutes and then weighed to obtain the weight Mcx; The total mass concentration of droplets carried in the smoke is C drop for: The mass concentration of droplets in the flue gas after correcting the effect of water vapor condensation C mid-drop for: Among them, V CX is the volume of the droplet sampler (1) after flushing water after sampling, ρ sea is the density of seawater at the outlet of the desulfurization tower; The mass concentration of droplets in the flue gas after conversion to standard oxygen content C cr-drop for: Among them, O cr The standard oxygen content specified in the emission standard, O s is the actual oxygen content in the flue gas.

2. The performance evaluation method of the flue gas seawater desulfurization device demister according to claim 1 is characterized in that: The specific operations of step 1) are: According to GB / T 16157, the measurement section of the demister outlet flue is divided into a grid structure with equal cross-sections.

3. The performance evaluation method of the flue gas seawater desulfurization device demister according to claim 1 is characterized in that: The specific operations of step 4) are: The droplet sampler (1) is cleaned with deionized water and then dried at 105°C for 2 hours. After drying, the droplet sampler (1) is placed in a drying dish to cool for 30 minutes.

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