CN112697548A - Method for sampling mercury in waste gas of fixed pollution source - Google Patents

Abstract

The invention relates to the technical field of environmental monitoring, in particular to a method for sampling mercury in waste gas of a fixed pollution source. The method is characterized in that: the waste gas is introduced through the gas inlet pipe and then downwards collides with the absorption liquid at the bottom of the cylinder body of the circulating fluidized bed to form a plurality of fine bubbles, and the particles impact the bottom of the cylinder body of the circulating fluidized bed to be dispersed due to the inertia effect, so that the particles are easily absorbed by the absorption liquid; if the concentration of the particulate matters in the monitored field environment is high, the particulate matters are captured by a method of washing absorption by absorption liquid and cyclone separation, so that mercury adsorbed on the particulate matters is absorbed by the absorption liquid, and the representativeness of a sample is ensured; the circulating loop in the absorption bottle is designed to enable the absorption liquid to naturally and circularly flow in the circulating loop in the absorption bottle, and meanwhile, the condensing device is additionally arranged outside the descending pipe, so that the time for the absorption liquid to fully contact with the granular mercury and the gaseous mercury during cooling and carry out mass transfer reaction is prolonged, and the retention time of the mercury in the absorption liquid can be prolonged even if the using amount of the absorption liquid is not increased.

Description

Method for sampling mercury in waste gas of fixed pollution source

Technical Field

The invention relates to the technical field of environmental monitoring, in particular to a method for sampling mercury in waste gas of a fixed pollution source.

Background

The coal is one of the largest emission sources of mercury in the atmosphere in China, and in the combustion process of the coal, the mercury in the coal is discharged to the atmosphere along with flue gas and mainly exists in 3 forms: gaseous elemental mercury (Hg)⁰) Gaseous divalent mercury (Hg)²⁺) And particulate mercury. The existing absorption bottle for sampling mercury in waste gas with a fixed pollution source is a large-scale bubble absorption tube, a certain amount of absorption liquid is filled in the absorption tube of the large-scale bubble absorption tube, gas is led into the absorption liquid from a glass thin tube through a small hole at the tube end below the liquid level to form small bubbles, the small bubbles enter the absorption liquid and are mainly used for absorbing gaseous or steam substances contained in the waste gas, the waste gas can be quickly diffused into the absorption liquid, gas-liquid mass transfer exchange is realized, the absorption efficiency of the mercury is better, but the control is neededThe sampling flow range is manufactured, because the inertia of gas molecules is small, under the condition of rapid air exhaust, pollutants are easy to escape after being exhausted by the flue gas sampler, so the flue gas sampler is usually set to be a fixed sampling flow of 0.3L/min, the flue gas flow rate in a chimney can not be consistent, parallel constant-speed sampling is difficult to complete, mercury adsorbed on particles in the flue gas can not be collected, and the accuracy of data is influenced. The Chinese invention patent (with the patent number of CN201910943697.9, the patent name is a mercury sampling device in fixed pollution source flue gas) discloses a mercury sampling device in fixed pollution source flue gas, which is characterized in that: comprises a constant temperature sampling gun, a constant temperature filter box, an ice bath absorption bottle box, a dehumidifying device, a sampling controller and a sampling air pump; the sampling head of the constant-temperature sampling gun extends into the flue, the outlet of the constant-temperature sampling gun is connected with the inlet of the constant-temperature filter box, the outlet of the constant-temperature filter box is connected with the inlet of the ice bath absorption bottle box, the outlet of the ice bath absorption bottle box is connected with the inlet of the dehumidifying device, the outlet of the dehumidifying device is connected with the inlet of the sampling controller, and the sampling air pump is further connected with the sampling controller; the ice bath absorption bottle box is provided with 14 absorption bottles, 7 absorption bottles are connected in series to form a group for sampling, and 14 absorption bottles are used for carrying out two groups of parallel sampling at a time; the serial 7 absorption bottles are numbered from left to right: the flue gas absorption device comprises a first absorption bottle, a second absorption bottle, a third absorption bottle, a fourth absorption bottle, a fifth absorption bottle, a sixth absorption bottle and a seventh absorption bottle, wherein the first absorption bottle, the second absorption bottle and the third absorption bottle are internally provided with diatomite-based composite adsorbents for trapping oxidized mercury in flue gas, and the fourth absorption bottle is internally provided with diatomite-based composite adsorbents for absorbing acid gas in the flue gas; and the fifth absorption bottle, the sixth absorption bottle and the seventh absorption bottle are internally provided with diatomite-based composite adsorbents for trapping gaseous element mercury in the flue gas. The Chinese invention patent (with the patent number of CN 201710133959.6, the patent name is a constant-speed sampling device and sampling method for fixed pollution source granular mercury and gaseous mercury) discloses a constant-speed sampling device and sampling method for fixed pollution source granular mercury and gaseous mercury, and the device and the method are used for sampling the fixed pollution source granular mercury and the gaseous mercury at constant speedThe device comprises: the device comprises a sampling nozzle, a sampling gun, a cyclone separator, an ash bucket, a fine particle filter, a gaseous mercury sampling pipe, a refrigerator, a dryer, a flow controller, an activated carbon mercury remover, a vacuum pump and an accumulation volume meter which are sequentially connected. Wherein, the sampling gun is arranged in the heating sleeve, and the cyclone separator, the fine particle filter and the activated carbon adsorption tube are arranged in the heat insulation box; the invention also discloses a sampling method of the device; the invention has the following advantages: 1. simultaneously collecting particle mercury and gaseous mercury samples; 2. the sampling process is insulated, so that mercury loss and mercury form conversion are prevented, and the sampling representativeness is improved; 3. two-stage dust removal of the cyclone separator and the fine particle filter ensures the representativeness of the sample in a high dust-containing environment. 4. The volume flow controller ensures constant-speed sampling; and 5, an activated carbon mercury remover is arranged at the rear part to prevent residual mercury from being discharged into the atmosphere.

In the prior art 1, a diatomite-based composite adsorbent is adopted to replace an absorption liquid in the existing standard method, and compared with a mercury chemical reaction absorption method in a solution of the existing standard method, the efficiency of physical adsorption, sequestration, mercury and compounds of the mercury is lower, because ionic reaction and redox reaction with acidic potassium permanganate are carried out in the method for collecting and measuring gaseous mercury and granular mercury, and meanwhile, the method of serially connecting a plurality of groups of adsorbent absorption bottles filled with the adsorbent can cause along-process pressure drop increase, and if a monitoring site with larger dust content is met, the micropores of the adsorbent are blocked by smoke dust, and a sampling air pump cannot work. In prior art 2, a cyclone separator, a fine particle filter and an activated carbon adsorption tube are added to capture mercury particles and try to remove the particles in advance, so that the problem that the sampling suction pump cannot work due to blocking of micropores of the adsorbent by smoke dust is avoided, but the method has the same problem as that in prior art 1, namely, compared with a mercury chemical reaction absorption method in solution of an existing standard method, the efficiency of physical adsorption and sequestration of mercury and compounds thereof by the adsorbent is lower.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a method for sampling mercury in waste gas of a fixed pollution source, which is characterized by comprising the following steps:

firstly, controlling the temperature of a heat tracing sampling gun at 120 ℃, collecting granular mercury and gaseous mercury on the premise of constant sampling, sequentially connecting the following seven sampling bottles in series according to the sequence of sequentially collecting the granular mercury, the gaseous bivalent mercury and the gaseous element mercury, collecting the granular mercury by using one circulating fluidized bed type mercury sampling bottle, wherein an absorption liquid is 50ml of 10% potassium hydroxide solution; collecting gaseous bivalent mercury by three suspension basket self-circulation mercury sampling bottles, wherein the absorption liquid is 50ml of 1.0mol/L potassium chloride solution; collecting gaseous element mercury by a short-tube self-circulation mercury sampling bottle and two long-tube self-circulation mercury sampling bottles, wherein absorption solutions are respectively 50ml of a 5% nitric acid and 10% hydrogen peroxide isometric mixed solution and 50ml of a 0.1mol/L potassium permanganate and 10% sulfuric acid isometric mixed solution; the heat tracing sampling gun, the circulating fluidized bed type mercury sampling bottle, the hanging basket self-circulating type mercury sampling bottle, the short pipe self-circulating type mercury sampling bottle, the long pipe self-circulating type mercury sampling bottle and the air pump are connected in sequence, a probe of the heat tracing sampling gun is blocked, the air pump is opened, the flow is observed, if the flow is below 0.02L/min, the air tightness of the system is proved to be good, the test can be started, otherwise, the air tightness is required to be checked section by section until the air tightness is checked.

And secondly, introducing the waste gas through the gas inlet pipe with the plug, then impacting the absorption liquid at the bottom of the cylinder of the circulating fluidized bed downwards to form a plurality of fine bubbles, impacting particles to the bottom of the cylinder of the circulating fluidized bed due to inertia effect to be dispersed, so that the particles are easily absorbed by the absorption liquid, fully contacting the waste gas with the absorption liquid to turn over to form bubbles, rising along a liquid column of the cylinder of the circulating fluidized bed, breaking the bubbles near the scale liquid level, enabling the air flow to enter the cyclone conical cylinder tangentially, collecting the particles and liquid drops in the waste gas along the wall of the cyclone conical cylinder after cyclone separation, flowing into the spherical condensation descending return pipe, then returning to the cylinder of the circulating fluidized bed again, and leading out the purified gas through.

And step three, the waste gas is guided into the gas guide pipe and then impacts absorption liquid in the lower bubbles downwards, the gas is uniformly distributed in the absorption liquid in the lower bubbles along the concave structure at the bottom of the hanging basket to form countless small bubbles, gas-liquid mixture formed by boiling after the absorption liquid in the lower bubbles contacts with the waste gas and conducts mass and heat rises to the upper bubbles along the calandria in the hanging basket, because density difference exists between the gas-liquid mixture of the calandria in the hanging basket and the absorption liquid in the spherical condensation descending pipe, the static pressure difference between the gas-liquid mixture and the absorption liquid drives the absorption liquid in the spherical condensation descending pipe to flow into the lower bubbles from the upper bubbles, the temperature of the absorption liquid is reduced, the absorption liquid continuously contacts with the waste gas in natural circulation to keep low temperature and prolong the retention time of the gaseous bivalent mercury in the absorption liquid, the absorption liquid fully reacts with the gaseous bivalent mercury and absorbs the gaseous mercury, and the absorbed waste.

And fourthly, the waste gas is guided into the gas guide-in pipe and then downwards impacts the absorption liquid at the bottom of the short pipe self-circulation type mercury sampling bottle body to form a plurality of extremely fine bubbles, the bubbles formed by full contact and turnover of the waste gas and the absorption liquid rise along the liquid column of the short pipe self-circulation type mercury sampling bottle body, the bubbles are broken and destroyed near the scale liquid level, as the density difference exists between the gas-liquid mixture of the short pipe self-circulation type mercury sampling bottle body and the absorption liquid in the spherical condensation descending circulation pipe, the static pressure difference between the gas-liquid mixture and the absorption liquid drives the absorption liquid in the spherical condensation descending circulation pipe to flow back into the short pipe self-circulation type mercury sampling bottle body, the absorption liquid is continuously contacted with the waste gas in natural circulation to keep low temperature and prolong the retention time of the gaseous element mercury in the absorption liquid, the absorption liquid and the gaseous.

And fifthly, the waste gas is guided into the gas inlet pipe with the plug and then downwards collides with the absorption liquid at the bottom of the gas absorption main pipe to form a plurality of extremely fine bubbles, the bubbles formed by full contact and turnover of the waste gas and the absorption liquid rise along the liquid column of the gas absorption main pipe and are broken near the scale liquid level, as the density difference exists between the gas-liquid mixture of the gas absorption main pipe and the absorption liquid in the spherical condensation descending reflux pipe, the static pressure difference between the gas absorption main pipe and the absorption liquid drives the absorption liquid in the spherical condensation descending reflux pipe to flow back into the gas absorption main pipe from the gas absorption side pipe, the absorption liquid continuously contacts with the waste gas in natural circulation to keep low temperature and prolong the retention time of gaseous mercury in the absorption liquid, the absorption liquid and the gaseous mercury are fully reacted and absorbed, and the purified gas is guided out through the.

The inventor finds that the ecological environment department, "cold atomic absorption spectrophotometry for mercury determination in stationary pollution source exhaust gas" (HJ/542-And (3) only filling large bubble absorption bottles with 10ml of absorption liquid respectively, wherein the absorption liquid is 0.1mol/L potassium permanganate and 10% sulfuric acid which are mixed in equal volume, sampling is carried out at the flow rate of 0.3L/min, the sampling time is 5-30 min, after the sampling is finished, the samples in the absorption liquid are recovered and subjected to constant volume, then the samples are analyzed, and the analysis method adopts a cold atom absorption spectrophotometry method. The method for sampling the mercury in the waste gas of the fixed pollution source has the following defects: firstly, it is possible that no particulate mercury can be collected, and regarding the particulate sampling and measuring technique, the "method for measuring particulate matter in exhaust gas from stationary pollution sources" (GB/T16157-1996) states that a particulate matter sampling pipe is extended into a flue or an exhaust cylinder from a sampling hole, a sampling nozzle is placed on a measuring point, a certain amount of dust-containing gas is extracted according to the principle of sampling particulate matter at a constant speed against an air flow, the concentration of particulate matter in the exhaust gas is calculated according to the amount of particulate matter trapped on the filter cylinder of the sampling pipe and the amount of gas extracted at the same time, since the concentration distribution of particulate matter on the sampling section of the flue or the exhaust cylinder is not uniform and the flue gas parameters such as the flow rate are also constantly changing, the methods of sampling at a constant speed and sampling at multiple points are usually adopted to obtain a representative particulate matter sample, and therefore sampling is carried out at a flow rate of 0.3, the requirement of constant-speed sampling cannot be met, and the particulate matters slide through the sampling pipe orifice due to inertia factors and are not collected; secondly, the sampling pipe is not heated, and mercury vapor is easy to condense and adhere to the sampling pipe; thirdly, the absorption bottle does not adopt a condensation measure, 10ml of absorption liquid is possible to boil and escape, and the gaseous mercury is lost along with the absorption liquid; fourthly, if a constant-speed sampling method is adopted, when the flue gas flow rate of the flue or the exhaust funnel is higher, the gas pump is easy to be extracted and separated by the flue gas sampler and escape without fully reacting with the absorption liquid because the inertia of the gaseous mercury is small under the condition of rapid gas extraction; fifthly, only single equal-volume mixed absorption liquid of 0.1mol/L potassium permanganate and 10 percent sulfuric acid is adopted, SO that the absorption liquid can not deal with high SO inevitably₂And (5) monitoring environment of concentration.

The inventor finds that the commonly used gaseous pollutant sampling method comprises a solution absorption method, an adsorbent retention method, a low-temperature condensation method and a natural sedimentation method, and the solution absorption method comprises two ways of increasing the using amount of the absorption liquid and prolonging the retention time of mercury in the absorption liquid in order to improve the efficiency of the absorption liquid for absorbing granular mercury and gaseous mercury. Increasing the absorption liquid quantity can influence the sample in follow-up absorption liquid and retrieve and constant volume work, because there is the restriction that detects the limit to mercury concentration detection analysis instrument method, when sample solution concentration is less than detecting the limit, degree of accuracy and precision receive the influence, and quality assurance and quality control just can't implement. The method is one of feasible methods for prolonging the retention time of mercury in absorption liquid by improving the design of an absorption bottle, according to the working principle of natural circulation, a circulation loop is designed in the absorption bottle, so that the absorption liquid flows in the circulation loop in the absorption bottle in a natural circulation manner, bubbles flow along with the absorption liquid in a natural circulation manner until the bubbles grow into larger bubbles and then are broken on the liquid surface, and meanwhile, a condensing device is additionally arranged outside a descending pipe, so that the time for the absorption liquid to fully contact with granular mercury and gaseous mercury during cooling and perform mass transfer reaction is prolonged, and the retention time of the mercury in the absorption liquid can be prolonged even if the consumption of the absorption liquid is not increased.

The inventor finds that in order to solve the problem that mercury vapor is easy to condense and adhere to a sampling tube, a constant-temperature quartz glass sampling tube is adopted, the temperature of the sampling tube is controlled at 120 ℃, granular mercury and gaseous mercury are collected on the premise of constant sampling, the following seven sampling bottles are sequentially connected in series according to the sequence of sequentially collecting the granular mercury, the gaseous bivalent mercury and the gaseous elemental mercury, the granular mercury is collected by one circulating fluidized bed type mercury sampling bottle, and absorption liquid is 50ml of 10% potassium hydroxide solution; collecting gaseous bivalent mercury by three suspension basket self-circulation mercury sampling bottles, wherein the absorption liquid is 50ml of 1.0mol/L potassium chloride solution; gaseous elemental mercury is collected by a short-tube self-circulation mercury sampling bottle and two long-tube self-circulation mercury sampling bottles, and absorption solutions are respectively 50ml of a mixed solution of 5% nitric acid and 10% hydrogen peroxide in equal volume and 50ml of a mixed solution of 0.1mol/L potassium permanganate and 10% sulfuric acid in equal volume.

The inventor finds that the circulating fluidized bed type mercury sampling bottle comprises a plug gas guide-out pipe, a plug gas guide-in pipe and a circulating fluidized bed type mercury sampling bottle body, wherein the circulating fluidized bed type mercury sampling bottle body comprises a cyclone cone cylinder, a circulating fluidized bed cylinder body and a spherical condensation descending return pipe, ice water with the temperature of 0-4 ℃ continuously flows through an outer sleeve of the spherical condensation descending return pipe, the plug gas guide-out pipe and the cyclone cone cylinder body form a cyclone separator, a tangential inlet of the cyclone cone cylinder is connected with the upper part of the circulating fluidized bed cylinder body, the bottom of the cyclone cone cylinder is provided with the spherical condensation descending return pipe, and the bottom end of the spherical condensation descending return pipe is connected with the lower part of the circulating fluidized bed cylinder body. The circulating fluidized bed barrel design is thick on upper portion, and the lower part is slender, and the slender absorption liquid column that can make in circulating fluidized bed barrel lower part increases, makes the contact that measured gas and absorption liquid can be abundant, and the bubble that can make the boiling expands on circulating fluidized bed barrel upper portion destroys rapidly, has stopper gas inlet pipe and cut straightly circulating fluidized bed barrel bottom, has stopper gas inlet pipe bottom and has welded the perforated plate, perforated plate open area and stopper gas inlet pipe cross sectional area match, make behind the air current impact perforated plate with even fine bubble blowout. The scales are marked on the circulating fluidized bed type mercury sampling bottle body, absorption liquid is added to enable the liquid level of the mercury sampling bottle body to be accurate to the scale positions, the scale positions are parallel and level to the top of the spherical condensation descending return pipe, the circulating fluidized bed type mercury sampling bottle body is required to be horizontally placed, the absorption liquid cannot submerge the spherical condensation descending return pipe due to the fact that the absorption liquid cannot be inclined, the bottle mouth of the circulating fluidized bed type mercury sampling bottle body is fixed with the rubber band for the plug, gas is prevented from being flushed away, and gas tightness inspection is required to be conducted before the mercury sampling bottle body. Waste gas is guided into the circulating fluidized bed cylinder through the plug gas guide pipe and then downwards impacts absorption liquid at the bottom of the circulating fluidized bed cylinder to form a plurality of fine bubbles, particulate matters impact the bottom of the circulating fluidized bed cylinder to be dispersed due to the inertia effect, so that the fine bubbles are easily absorbed by the absorption liquid, the bubbles formed by full contact and turnover of the waste gas and the absorption liquid rise along a liquid column of the circulating fluidized bed cylinder, the bubbles are broken and extinguished near a scale liquid level, airflow tangentially enters the cyclone cone cylinder, the particulate matters and liquid drops in the waste gas are collected along the wall of the cyclone cone cylinder after cyclone separation and flow into the spherical condensation descending return pipe and then return to the circulating fluidized bed cylinder again, and the purified gas is guided out through the.

The inventor finds that the hanging basket self-circulation type mercury sampling bottle comprises a hanging basket self-circulation type mercury sampling bottle body and a hanging basket air guide assembly with a plug, wherein the hanging basket self-circulation type mercury sampling bottle body is of a dumbbell-shaped structure, an upper bubble and a lower bubble are respectively arranged on the upper side and the lower side, the upper bubble and the lower bubble are connected through a sleeve, the hanging basket is placed in the sleeve, spherical condensation descending pipes are arranged on two sides of the upper bubble and the lower bubble, and ice water with the temperature of 0-4 ℃ continuously flows through outer sleeves of the spherical condensation descending pipes. Utensil stopper hanging basket air guide assembly includes that the gas induction pipe passes utensil dull polish quartz glass stopper bubble down of utensil dull polish quartz glass, utensil dull polish quartz glass stopper, hangs the basket, the gas induction pipe passes the straight cutting of utensil dull polish quartz glass stopper, and the welding of gas induction pipe lower extreme has hanging the basket, it constitutes for a set of parallel calandria to hang the basket, fills in the annular space between gas induction pipe and the sleeve pipe, and the bottom is the indent structure. Scales are marked on the hanging basket self-circulation type mercury sampling bottle body, absorption liquid is added to enable the liquid level of the hanging basket self-circulation type mercury sampling bottle body to be accurate to the scale position, the hanging basket self-circulation type mercury sampling bottle body is kept horizontally placed, the absorption liquid cannot submerge the spherical condensation descending pipe due to the fact that the hanging basket self-circulation type mercury sampling bottle body cannot incline, and a frosted bottle opening of the hanging basket self-circulation type mercury sampling bottle body is fixed with the frosted quartz glass plug through a rubber band to prevent gas from. The waste gas is guided into the gas guide pipe and then impacts the absorption liquid in the lower bubble downwards, the gas is uniformly distributed in the absorption liquid in the lower bubble along the concave structure at the bottom of the hanging basket to form countless small bubbles, the absorption liquid in the lower bubble contacts with the waste gas, the gas-liquid mixture formed by boiling after mass transfer and heat transfer rises to the upper bubble along the calandria in the hanging basket, because the density difference exists between the gas-liquid mixture of the calandria in the hanging basket and the absorption liquid in the spherical condensation descending pipe, the static pressure difference between the absorption liquid and the spherical condensation descending pipe drives the absorption liquid in the spherical condensation descending pipe to flow into the lower bubble from the upper bubble, the temperature of the absorption liquid is reduced, the absorption liquid continuously contacts with the waste gas in natural circulation to keep low temperature and prolong the retention time of the gaseous bivalent mercury in the absorption liquid, the absorption liquid fully reacts with the gaseous bivalent mercury and absorbs the gaseous mercury, and.

The inventor finds that the short tube self-circulation type mercury sampling bottle comprises a gas outlet tube, a gas inlet tube, a short tube self-circulation type mercury sampling bottle body, a connecting through-flow tube and a spherical condensation descending circulating tube, wherein the short tube self-circulation type mercury sampling bottle body is designed to be thick at the upper part and thin at the lower part, an absorption liquid column can be heightened by the thin and thin lower part of the short tube self-circulation type mercury sampling bottle body, a detected gas can be fully contacted with the absorption liquid, bubbles which are overturned can be rapidly broken by the expansion of the upper part of the short tube self-circulation type mercury sampling bottle body, ice water with the temperature of 0-4 ℃ continuously flows through an outer sleeve of the spherical condensation descending circulating tube, the gas outlet tube and the gas inlet tube penetrate through a quartz glass plug, the quartz glass plug is matched with the short tube self-circulation type mercury sampling frosted bottle body, and the upper, the lower end of the spherical condensation descending circulating pipe is connected with the bottom of the short pipe self-circulation type mercury sampling bottle body for through flow. The short tube self-circulation type mercury sampling bottle body, the connecting draft tube and the spherical condensation descending circulating tube form a natural circulation loop, the gas inlet tube is directly inserted into the bottom of the short tube self-circulation type mercury sampling bottle body, the bottom end of the gas inlet tube is welded with a porous screen plate, the opening area of the porous screen plate is equivalent to the section area of the gas inlet tube, and airflow is ejected out by uniform ultrafine bubbles after impacting the porous screen plate. The short tube self-circulation type mercury sampling bottle body is marked with scales, absorption liquid is added to enable the liquid level of the short tube self-circulation type mercury sampling bottle body to be accurate to the scale position, the scale position is 1cm higher than that of the connecting through flow tube, the short tube self-circulation type mercury sampling bottle body is required to be horizontally placed, the absorption liquid cannot submerge the connecting through flow tube due to the fact that the short tube self-circulation type mercury sampling bottle body cannot be inclined, the bottle mouth of the short tube self-circulation type mercury sampling bottle body is fixed with a rubber band for a quartz glass plug, gas. The waste gas is guided through the gas guide pipe and then downwards collides with absorption liquid at the bottom of the short pipe self-circulation type mercury sampling bottle body to form countless extremely fine bubbles, the bubbles formed by full contact and turnover of the waste gas and the absorption liquid rise along a liquid column of the short pipe self-circulation type mercury sampling bottle body, the bubbles are broken near a scale liquid level, as a gas-liquid mixture of the short pipe self-circulation type mercury sampling bottle body and the absorption liquid in the spherical condensation descending circulation pipe have density difference, the static pressure difference between the gas-liquid mixture and the absorption liquid drives the absorption liquid in the spherical condensation descending circulation pipe to flow back into the short pipe self-circulation type mercury sampling bottle body, the absorption liquid continuously contacts with the waste gas in natural circulation to keep low temperature and prolong the retention time of gaseous element mercury in the absorption liquid, the absorption liquid and the gaseous element mercury fully react and absorb, and the.

The inventor discovers that the long-tube self-circulation type mercury sampling bottle comprises an air-plugging output tube, an air-plugging input tube and a long-tube self-circulation type mercury sampling bottle body, wherein the long-tube self-circulation type mercury sampling bottle body comprises a gas absorption side tube, a connecting tube, a gas absorption main tube and a spherical condensation descending return tube, the outer sleeve of the spherical condensation descending return tube continuously flows 0-4 ℃ ice water, the air-plugging output tube is matched with the gas absorption side tube in a grinding way, the lower part of the gas absorption side tube and the upper part of the gas absorption main tube are communicated through the connecting tube, the bottom of the gas absorption side tube is designed with the spherical condensation descending return tube, and the bottom of the spherical condensation descending. The gas absorption main pipe, the connecting pipe, the gas absorption side pipe and the spherical condensation descending reflux pipe form a natural circulation loop, the gas input pipe with the plug is directly inserted into the bottom of the gas absorption main pipe, the bottom end of the gas input pipe with the plug is welded with a porous sieve plate, the opening area of the porous sieve plate is equivalent to the section area of the gas input pipe with the plug, and gas flow is ejected out by uniform superfine bubbles after impacting the porous sieve plate. The mark has the scale on the long tube self-loopa formula mercury sampling bottle, adds the absorption liquid and makes its liquid level accurate to the scale position, and this scale position is 1cm higher than the connecting pipe, should keep long tube self-loopa formula mercury sampling bottle horizontal placing, must not incline and lead to the absorption liquid can't submerge the connecting pipe, and the bottleneck of long tube self-loopa formula mercury sampling bottle is fixed with utensil stopper rubber band to prevent that gas from breaking open, should carry out the gas tightness inspection before the use. The waste gas is guided into the gas inlet pipe with the plug and then downwards collides with the absorption liquid at the bottom of the gas absorption main pipe to form a plurality of extremely fine bubbles, the bubbles formed by full contact and turnover of the waste gas and the absorption liquid rise along the liquid column of the gas absorption main pipe and are broken near the scale liquid level, as the density difference exists between the gas-liquid mixture of the gas absorption main pipe and the absorption liquid in the spherical condensation descending reflux pipe, the static pressure difference between the gas-liquid mixture and the absorption liquid drives the absorption liquid in the spherical condensation descending reflux pipe to flow back into the gas absorption main pipe from the gas absorption side pipe, the absorption liquid keeps low temperature in continuous contact with the waste gas in natural circulation and prolongs the retention time of gaseous element mercury in the absorption liquid, the absorption liquid and the gaseous element mercury are fully reacted and absorbed, and the purified gas is guided out by the.

Compared with the prior art, the invention at least has the following advantages: firstly, waste gas is introduced through an air-plugging inlet pipe and then downwards collides with absorption liquid at the bottom of a cylinder body of the circulating fluidized bed to form a plurality of fine bubbles, and particles impact the bottom of the cylinder body of the circulating fluidized bed to be dispersed due to the inertia effect, so that the particles are easily absorbed by the absorption liquid; secondly, if the concentration of the particulate matters in the monitored field environment is high, the particulate matters are captured by a method of washing absorption by absorption liquid and cyclone separation, so that mercury adsorbed on the particulate matters is absorbed by the absorption liquid, and the representativeness of a sample is ensured; according to the natural circulation working principle, the circulation loop is designed in the absorption bottle, so that the absorption liquid naturally and circularly flows in the circulation loop in the absorption bottle, bubbles naturally and circularly flow along with the absorption liquid until the bubbles grow into larger bubbles and then are broken on the liquid level, and meanwhile, a condensing device is additionally arranged outside the descending pipe, so that the time for the absorption liquid to fully contact with the granular mercury and the gaseous mercury and perform mass transfer reaction is prolonged while the absorption liquid is cooled, and the retention time of the mercury in the absorption liquid can be prolonged even if the consumption of the absorption liquid is not increased.

Drawings

FIG. 1 is a schematic structural diagram of a fixed pollution source waste gas mercury sampling method according to the present invention.

FIG. 2 is a schematic structural diagram of a large sample A of the method for sampling mercury from waste gas of a fixed pollution source.

FIG. 3 is a schematic structural diagram of a large sample B of the fixed pollution source waste gas mercury sampling method of the invention.

FIG. 4 is a schematic structural diagram of a large sample C of the fixed pollution source waste gas mercury sampling method of the present invention.

FIG. 5 is a schematic diagram of a D-D section arrangement structure of the method for sampling mercury in waste gas from a fixed pollution source.

FIG. 6 is a schematic structural diagram of a large sample E of the method for sampling mercury from waste gas of a fixed pollution source.

FIG. 7 is a schematic structural diagram of a bulk sample F of the fixed pollution source waste gas mercury sampling method of the present invention.

I-heat tracing sampling gun II-circulating fluidized bed type mercury sampling bottle

III-hanging basket self-circulation mercury sampling bottle, IV-short pipe self-circulation mercury sampling bottle

V-long tube self-circulation mercury sampling bottle VI-air extracting pump

1-gas-plugging delivery pipe 2-gas-plugging delivery pipe 3-circulating fluidized bed type mercury sampling bottle body

4-cyclone conical cylinder 5-circulating fluidized bed cylinder 6-spherical condensation descending return pipe

7-hanging basket self-circulation mercury sampling bottle body 8-hanging basket air guide assembly with plug 9-upper air bubble

10-spherical condensation downcomer 11-sleeve 12-lower bubble 13-gas inlet pipe

14-gas outlet pipe 15-frosted quartz glass plug 16-suspension basket

17-gas delivery pipe 18-gas inlet pipe 19-short pipe self-circulation type mercury sampling bottle body

20-connecting draft tube 21-spherical condensation descending circulating tube

22-gas output pipe with plug 23-gas input pipe with plug 24-long pipe self-circulation mercury sampling bottle body

25-gas absorption side tube 26-connecting tube 27-gas absorption Main tube

28-spherical condensing descending return pipe.

Detailed Description

The invention is further described with reference to the following detailed description of embodiments and drawings.

As shown in fig. 1, fig. 2, fig. 3, fig. 4, fig. 5, fig. 6, and fig. 7, the method for sampling mercury in exhaust gas from a stationary pollution source is characterized in that: firstly, controlling the temperature of a heat tracing sampling gun I at 120 ℃, collecting granular mercury and gaseous mercury on the premise of constant sampling, sequentially connecting the following seven sampling bottles in series according to the sequence of sequentially collecting the granular mercury, the gaseous bivalent mercury and the gaseous element mercury, collecting the granular mercury by a circulating fluidized bed type mercury sampling bottle II, and collecting 10% potassium hydroxide solution with 50ml of absorption liquid; collecting gaseous bivalent mercury by three suspension basket self-circulation mercury sampling bottles III, wherein the absorption liquid is 50ml of 1.0mol/L potassium chloride solution; collecting gaseous element mercury by a short-tube self-circulation mercury sampling bottle IV and two long-tube self-circulation mercury sampling bottles V, wherein absorption solutions are respectively 50ml of a 5% nitric acid and 10% hydrogen peroxide isometric mixed solution and 50ml of a 0.1mol/L potassium permanganate and 10% sulfuric acid isometric mixed solution; the method comprises the following steps of sequentially connecting a heat tracing sampling gun I, a circulating fluidized bed type mercury sampling bottle II, a hanging basket self-circulation type mercury sampling bottle III, a short pipe self-circulation type mercury sampling bottle IV, a long pipe self-circulation type mercury sampling bottle V and an air suction pump VI, blocking a probe of the heat tracing sampling gun I, opening the air suction pump VI, observing flow, and if the flow is below 0.02L/min, proving that the air tightness of the system is good, starting testing, otherwise, checking the air tightness section by section until the air tightness is checked.

And secondly, the waste gas is introduced through the gas inlet pipe 2 and then downwards impacts the absorption liquid at the bottom of the circulating fluidized bed cylinder 5 to form a plurality of fine bubbles, the particles impact the bottom of the circulating fluidized bed cylinder 5 due to inertia effect and are dispersed, so that the particles are easily absorbed by the absorption liquid, the waste gas and the absorption liquid are fully contacted and overturned to form bubbles which rise along a liquid column of the circulating fluidized bed cylinder 5, the bubbles are broken near the scale liquid level, the airflow tangentially enters the cyclone cone cylinder 4, the particles and liquid drops in the waste gas are collected along the wall of the cyclone cone cylinder 4 after cyclone separation and flow into the spherical condensation descending return pipe 6 and then return to the circulating fluidized bed cylinder 5 again, and the purified gas is led out through the gas inlet pipe 1.

Step three, the waste gas is guided in by the gas guide pipe 13 and then impacts the absorption liquid in the lower bubble downwards, the gas is uniformly distributed in the absorption liquid in the lower bubble 12 along the concave structure at the bottom of the hanging basket 16 to form countless small bubbles, the absorption liquid in the lower bubble 12 contacts with the waste gas, the gas-liquid mixture formed by boiling after mass transfer and heat transfer rises to the upper bubble along the calandria in the hanging basket 16, because the density difference exists between the gas-liquid mixture of the calandria in the suspension basket 16 and the absorption liquid in the spherical condensation downcomer 10, the absorption liquid in the spherical condensation downcomer 10 is driven to flow into the lower bubbles from the upper bubbles by the static pressure difference of the two, the temperature of the absorption liquid is reduced, the absorption liquid is continuously contacted with the exhaust gas in the natural circulation to keep the low temperature and prolong the retention time of the gaseous bivalent mercury in the absorption liquid, the absorption liquid and the gaseous bivalent mercury fully react and absorb, and the absorbed exhaust gas is output through the gas guide pipe 14.

And fourthly, the waste gas is guided into the gas guide-in pipe 18 and then downwards collides with the absorption liquid at the bottom of the short pipe self-circulation type mercury sampling bottle body 19 to form a plurality of extremely fine bubbles, the bubbles formed by full contact and turnover of the waste gas and the absorption liquid rise along the liquid column of the short pipe self-circulation type mercury sampling bottle body 19, the bubbles are broken and extinguished near the scale liquid level, as the density difference exists between the gas-liquid mixture of the short pipe self-circulation type mercury sampling bottle body 19 and the absorption liquid in the spherical condensation descending circulation pipe 21, the static pressure difference between the two drives the absorption liquid in the spherical condensation descending circulation pipe 21 to flow back into the short pipe self-circulation type mercury sampling bottle body 19, the absorption liquid keeps low temperature in continuous contact with the waste gas in natural circulation and prolongs the retention time of the gaseous element mercury in the absorption liquid, the absorption liquid and the gaseous element mercury are fully reacted.

Step five, the waste gas is guided into the gas inlet pipe 23 and then collides with the absorption liquid at the bottom of the gas absorption main pipe 27 downwards to form a plurality of extremely fine bubbles, the bubbles formed by full contact and turnover of the waste gas and the absorption liquid rise along the liquid column of the gas absorption main pipe 27 and are broken near the scale liquid level, as the density difference exists between the gas-liquid mixture of the gas absorption main pipe 27 and the absorption liquid in the spherical condensation descending return pipe 28, the static pressure difference between the gas absorption main pipe and the absorption liquid drives the absorption liquid in the spherical condensation descending return pipe 28 to flow back into the gas absorption main pipe 27 from the gas absorption side pipe 25, the absorption liquid keeps low temperature in continuous contact with the waste gas in natural circulation and prolongs the retention time of the gaseous mercury in the absorption liquid, the absorption liquid and the gaseous mercury are fully reacted and absorbed, and the purified gas is guided out by the gas outlet pipe 22.

Variations and modifications to the above-described embodiments may occur to those skilled in the art, which fall within the scope and spirit of the above description. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and variations of the present invention should fall within the scope of the claims of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims (9)

1. The method for sampling the mercury in the waste gas of the fixed pollution source is characterized by comprising the following steps: firstly, controlling the temperature of a heat tracing sampling gun at 120 ℃, and collecting granular mercury and gaseous mercury on the premise of constant sampling; sequentially connecting a heat tracing sampling gun, a circulating fluidized bed type mercury sampling bottle, a hanging basket self-circulating type mercury sampling bottle, a short pipe self-circulating type mercury sampling bottle, a long pipe self-circulating type mercury sampling bottle and an air pump, blocking a probe of the heat tracing sampling gun, opening the air pump, observing the flow, and if the flow is below 0.02L/min, proving that the air tightness of the system is good, and starting the test, otherwise, checking the air tightness section by section until the air tightness is checked; secondly, introducing the waste gas through a gas inlet pipe with a plug, and then impacting the absorption liquid at the bottom of the cylinder of the circulating fluidized bed downwards to form a plurality of fine bubbles, wherein the particles impact the bottom of the cylinder of the circulating fluidized bed due to inertia effect and are dispersed, so that the particles are easily absorbed by the absorption liquid; step three, the waste gas is guided into the gas guide pipe and then impacts the absorption liquid in the lower bubbles downwards, the gas is uniformly distributed in the absorption liquid in the lower bubbles along the concave structure at the bottom of the suspension basket to form countless small bubbles, the absorption liquid and gaseous bivalent mercury fully react and absorb, and the absorbed waste gas is output through the gas guide pipe; step four, after being guided through the gas guide-in pipe, the waste gas impacts the absorption liquid at the bottom of the short pipe self-circulation type mercury sampling bottle body downwards to form a plurality of extremely fine bubbles, the absorption liquid fully reacts and absorbs with gaseous elemental mercury, and the purified gas is guided out through the gas guide-out pipe; and step five, introducing the waste gas through the gas plugging input pipe, then downwards impacting the absorption liquid at the bottom of the gas absorption main pipe to form a plurality of extremely fine bubbles, fully reacting and absorbing the absorption liquid and gaseous elemental mercury, and leading out the purified gas through the gas plugging output pipe.

2. The fixed pollution source exhaust gas mercury sampling method according to claim 1, characterized in that: according to the order of collecting granular mercury, gaseous bivalent mercury and gaseous element mercury in turn, the following seven sampling bottles are connected in series in turn.

3. The fixed pollution source exhaust gas mercury sampling method according to claim 1, characterized in that: granular mercury was collected in a circulating fluidized bed mercury sampling bottle and the absorption solution was 50ml of 10% potassium hydroxide solution.

4. The fixed pollution source exhaust gas mercury sampling method according to claim 1, characterized in that: gaseous bivalent mercury is collected by three suspension basket self-circulation mercury sampling bottles, and the absorption liquid is 50ml of 1.0mol/L potassium chloride solution.

5. The fixed pollution source exhaust gas mercury sampling method according to claim 1, characterized in that: gaseous elemental mercury is collected by a short-tube self-circulation mercury sampling bottle and two long-tube self-circulation mercury sampling bottles, and absorption solutions are respectively 50ml of a mixed solution of 5% nitric acid and 10% hydrogen peroxide in equal volume and 50ml of a mixed solution of 0.1mol/L potassium permanganate and 10% sulfuric acid in equal volume.

6. The fixed pollution source exhaust gas mercury sampling method according to claim 1, characterized in that: the bubbles formed by full contact and turnover of the waste gas and the absorption liquid rise along the liquid column of the cylinder of the circulating fluidized bed, the bubbles are broken near the liquid level of the scale, the air flow enters the cyclone cone cylinder tangentially, the particulate matters and liquid drops in the waste gas are separated by cyclone, are converged along the wall of the cyclone cone cylinder, flow into the spherical condensation descending return pipe and then return to the cylinder of the circulating fluidized bed again, and the purified gas is led out through the gas outlet pipe with a plug.

7. The fixed pollution source exhaust gas mercury sampling method according to claim 1, characterized in that: the absorption liquid in the lower bubble contacts with the waste gas, the absorption liquid is subjected to mass transfer and heat transfer, the gas-liquid mixture formed by boiling rises to the upper bubble along the exhaust pipe in the hanging basket, and the density difference exists between the gas-liquid mixture of the exhaust pipe in the hanging basket and the absorption liquid in the spherical condensation descending pipe, so that the static pressure difference between the gas-liquid mixture and the absorption liquid drives the absorption liquid in the spherical condensation descending pipe to flow into the lower bubble from the upper bubble, the temperature of the absorption liquid is reduced, the absorption liquid continuously contacts with the waste gas in a natural circulation to keep low temperature, and the retention time of the gaseous bivalent mercury in the absorption liquid.

8. The fixed pollution source exhaust gas mercury sampling method according to claim 1, characterized in that: the gas bubbles formed by full contact and overturning of the waste gas and the absorption liquid rise along the liquid column of the short tube self-circulation type mercury sampling bottle body, the gas bubbles are broken near the scale liquid level, the density difference exists between the gas-liquid mixture of the short tube self-circulation type mercury sampling bottle body and the absorption liquid in the spherical condensation descending circulation tube, the static pressure difference between the gas-liquid mixture of the short tube self-circulation type mercury sampling bottle body and the absorption liquid in the spherical condensation descending circulation tube drives the absorption liquid in the spherical condensation descending circulation tube to flow back into the short tube self-circulation type mercury sampling bottle body, and the absorption liquid is continuously contacted with the waste gas in.

9. The fixed pollution source exhaust gas mercury sampling method according to claim 1, characterized in that: the gas-liquid mixture of the gas absorption main pipe and the absorption liquid in the spherical condensation descending reflux pipe have density difference, the static pressure difference between the gas absorption main pipe and the absorption liquid drives the absorption liquid in the spherical condensation descending reflux pipe to flow back into the gas absorption main pipe from the gas absorption side pipe, and the absorption liquid continuously contacts with the waste gas in natural circulation to keep low temperature and prolong the retention time of gaseous element mercury in the absorption liquid.

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