CN105115924A - Method and apparatus for testing demercuration performance of carbon-based adsorbent - Google Patents

Abstract

The invention provides a method and device for testing the mercury removal performance of a carbon-based adsorbent, which specifically includes the process of preparing mixed gas, adsorption, post-treatment and detection. Prepare mixed gas to simulate the flue gas environment in the actual industry, and then conduct experiments to test the mercury removal performance of carbon-based adsorbents. The method and device provided by the invention are simple in operation, small in gas consumption, short in test time, low in cost, can truly reflect the mercury removal effect of the adsorbent, have high reliability, and have important guiding significance and reference value.

Description

A method and device for testing the mercury removal performance of carbon-based adsorbent

technical field

The invention relates to the field of performance testing, in particular to the testing of the mercury removal performance of a carbon-based adsorbent.

Background technique

In addition to CO ₂ , SO _x , NO _x , and PM10 pollution caused by coal combustion, the environmental pollution caused by harmful trace elements represented by mercury is becoming more and more prominent. Mercury is not easy to remove after it is discharged into the environment, and accumulates in the environment for a long time through the biological chain, causing long-term toxic effects on organisms and humans. Studies have shown that in the past 20 years, the concentration of mercury in the global atmosphere has been increasing year by year, especially in the past decade. In March 2011, the U.S. EPA promulgated the latest power plant pollutant emission standards, which imposed strict restrictions on mercury emissions in power plant coal-fired flue gas. In July 2011, the Ministry of Environmental Protection of China promulgated the latest "Emission Standards of Air Pollutants for Thermal Power Plants (GB13223-2011)", requiring that from 2015 onwards, the emission of mercury and its compounds in coal-fired flue gas of power plants should be controlled at 0.03 mg/Nm ³ or less. In the context of China's rapid economic development, coal-fired power plants and large and medium-sized coal-fired industrial boilers are still developing vigorously, and the prevention and control of coal-fired pollution is an unavoidable problem. Therefore, it is necessary to strengthen the research on the control of coal-fired mercury pollution, establish a systematic scientific theory, and develop economical and efficient mercury pollution control technologies.

Mercury in coal-fired flue gas mainly exists in three forms: particulate mercury (Hg ^p ), divalent mercury (Hg ²⁺ ) and elemental mercury (Hg ⁰ ). Particulate mercury can be removed by dust removal equipment. Divalent mercury is easily absorbed and removed by wet flue gas desulfurization equipment and most adsorbents. Elemental mercury is difficult to be removed by existing Absorbed by pollution control devices. In recent years, Chinese scholars have conducted a lot of research on the adsorption of mercury by adsorbents. In addition to fly ash, calcium-based adsorbents, noble metal adsorbents, biomass-based adsorbents, and ore-based adsorbents, the most widely used adsorbents are It is a carbon-based adsorbent. By modifying activated carbon, better mercury adsorption effect was obtained. For example, the relevant literature records the nitric acid modified activated carbon adsorbent for flue gas demercuration, its preparation method and application, and the activated carbon modified by nitric acid has a good mercury removal effect; The iron-chlorine modified activated carbon adsorbent for mercury removal, the mercury removal efficiency is improved by impregnating the activated carbon with the ferric nitrate-chloric acid mixed solution. Although the modified carbon-based adsorbent has a good effect on mercury removal, it is impossible to directly test its mercury removal performance in actual production to evaluate its advantages and disadvantages. Therefore, it is necessary to simulate the actual work under laboratory conditions. In order to better evaluate its performance and reduce the cost of industrial testing, the mercury removal performance test of the adsorbent can be carried out under the condition of the adsorbent.

Contents of the invention

The purpose of the present invention is to provide a method and device for testing the mercury removal performance of a carbon-based adsorbent.

The technical solution adopted to achieve the purpose of the present invention is as follows, a method for testing the mercury removal performance of a carbon-based adsorbent, including preparation of mixed gas, adsorption, post-treatment and detection process, the method specifically includes the following steps:

1) Load 50 mg of carbon-based adsorbent samples with a particle size of 2 to 4 mm into an adsorption reactor.

2) Mix N ₂ , CO ₂ , NO, NO ₂ , HCl, SO ₂ , and O ₂ , and bring mercury vapor into the mixed gas through the mercury permeation tube before N ₂ is mixed; the prepared mixed gas consists of 20ppmNO ₂ , 300ppmNO , 5~10ppmHCl, 300ppmSO ₂ , 6%O ₂ , 13.5%CO ₂ , 15±1ng/L mercury and N ₂ , where N ₂ is used as the balance gas.

3) Heat the prepared mixed gas to 100-150°C; then pass it into the adsorption reactor, the total flow rate of the mixed gas is 1L/min, and the temperature of the adsorption reactor is 140°C.

4) The mixed gas processed in step 3) is passed into a heating box, heated to 100° C. and then kept warm.

5) The mixed gas treated in step 4) is fed into 10% SnCl ₂ solution and 10% NaOH solution in sequence.

6) detect and analyze the mixed gas after step 5) processing; adopt double-beam cold atomic absorption method to measure and calculate the mercury adsorption amount by the area between the integral breakthrough curve and the reference line; its calculation formula is

A represents the amount of mercury adsorbed by the carbon-based adsorbent (μg/g).

C ₀ represents the baseline mixed gas mercury concentration (ng/L).

C _t represents the mercury concentration (ng/L) in the mixed gas during the test.

m represents the mass (g) of the carbon-based adsorbent.

c represents the curve of the mercury concentration in the mixed gas changing with time.

Based on the above method for testing the mercury removal performance of carbon-based adsorbents, the present invention also provides a device for testing the mercury removal performance of carbon-based adsorbents, including a gas distribution system, a mercury generating device, a fixed bed reactor, a mercury form conversion system and Mercury Analysis System.

The gas distribution system includes generators and gas distribution branches for the various gases mentioned above. The mercury generating device includes a mercury permeation tube, a U-shaped tube and a constant temperature oil bath. The mercury permeation tube is located in a U-shaped tube, and the U-shaped tube is located in a constant temperature oil bath. The fixed bed reactor is an adsorption reactor. The mercury form conversion system includes a heating box and two washing bottles, and the two washing bottles are respectively equipped with 10% SnCl ₂ solution and 10% NaOH solution. The mercury analysis system includes a mercury analyzer and a general computer.

The mercury generating device is installed in the _N2 gas distribution branch. The gas outlet of the gas distribution system is connected with the gas inlet of the fixed bed reactor. The gas outlet of the fixed bed reactor is connected with the gas inlet of the heating box. The gas outlet of the heating box is connected with the gas inlet of the washing bottle I containing ₁₀ % SnCl2 solution. The gas outlet of the gas washing bottle I is connected with the air inlet of the gas washing bottle II filled with 10% NaOH solution. The gas outlet of the gas washing bottle II is connected with mercury analysis equipment.

Further, the fixed-bed reactor can be precisely controlled to 0.1°C, and can simulate the working environment of the adsorbent under actual working conditions, and can be used as a test device for various gas-solid reactions.

Furthermore, from the gas distribution system to the mercury form conversion system, the device conducts gas preheating and heat preservation through an electric heating belt throughout the process.

Technical effect of the present invention is beyond doubt, has following beneficial effect:

1. The present invention uses a small simulated flue gas platform in the laboratory to test the mercury removal performance of carbon-based adsorbents, which avoids the disadvantages of complex operation, large gas consumption, long test time, and high cost of medium-sized or large-scale test devices, and has important guiding significance and reference value;

2. This simulation test method and system can truly restore the actual working condition of the adsorbent working environment, can truly reflect the mercury removal effect of the adsorbent, has high reliability, and is easy to operate.

Description of drawings

Fig. 1 is a schematic diagram of the testing device of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, but it should not be understood that the scope of the subject matter of the present invention is limited to the following embodiments. Without departing from the above-mentioned technical idea of the present invention, various replacements and changes made according to common technical knowledge and conventional means in this field shall be included in the protection scope of the present invention.

Example 1:

A method for testing the mercury removal performance of a carbon-based adsorbent, comprising the process of preparing mixed gas, adsorption, post-treatment and detection, the method specifically includes the following steps:

1) 50 mg of carbon-based adsorbent samples with a particle size of 2 to 4 mm are loaded into the adsorption reactor;

2) Mix N ₂ , CO ₂ , NO, NO ₂ , HCl, SO ₂ , and O ₂ , and bring mercury vapor into the mixed gas through the mercury permeation tube before N ₂ is mixed; the prepared mixed gas consists of 20ppmNO ₂ , 300ppmNO , 5~10ppmHCl, 300ppmSO ₂ , 6%O ₂ , 13.5%CO ₂ , 15±1ng/L mercury and N ₂ ; where N ₂ is used as a balance gas to ensure a constant total flow of gas, and through constant adjustment, other The gas concentration is within the specified range; when the amount of other gases reaches a fixed value, the amount of nitrogen will also be fixed; when the concentration of other gases changes, the nitrogen will change accordingly; the prepared mixed gas is as real as possible The environment of simulating the actual industrial flue gas;

3) Heat the prepared mixed gas to 100-150°C; then pass it into the adsorption reactor, the total flow rate of the mixed gas is 1L/min, and the temperature of the adsorption reactor is 140°C;

4) The mixed gas processed in step 3) is passed into the heating box, and it is heated to 100°C and then kept warm;

5) The mixed gas after step 4) is passed into 10% SnCl ₂ solution and 10% NaOH solution successively _; acid gas to avoid corrosion to the mercury detector; in actual operation, the ventilation sequence can be exchanged;

6) detect and analyze the mixed gas after step 5) processing; adopt double-beam cold atomic absorption method to measure and calculate the mercury adsorption amount by the area between the integral breakthrough curve and the reference line; its calculation formula is

A represents the adsorption amount of mercury on the carbon-based adsorbent (μg/g);

C ₀ represents the mercury concentration of the baseline mixed gas (ng/L);

C _t represents the mercury concentration in the mixed gas during the test (ng/L);

m represents the mass of carbon-based adsorbent (g);

c represents the curve of the mercury concentration in the mixed gas changing with time.

Example 2:

Based on a method for testing the mercury removal performance of carbon-based adsorbents in Example 1, this example provides a device for testing the mercury removal performance of carbon-based adsorbents, including a gas distribution system, a mercury generating device, a fixed-bed reactor, and mercury form Conversion systems and mercury analysis systems.

The gas distribution system includes generators and gas distribution branches for the various gases mentioned above. The gas generated by each gas generator is gathered together through its own gas distribution branch. A gas generator can be used to control the flow of gas. The mercury generating device includes a mercury permeation tube, a U-shaped tube and a constant temperature oil bath. The mercury permeation tube is located in a U-shaped tube, and the U-shaped tube is located in a constant temperature oil bath. The mercury generator is used to provide stable elemental mercury vapor. Mercury is obtained from the mercury permeation tube in the mercury generator, and the amount of mercury permeation increases with the temperature of the oil bath, that is, the mercury concentration is controlled by temperature.

The fixed bed reactor is an adsorption reactor, specifically a quartz glass tube whose temperature is controlled by a tube furnace, with a diameter of 8-10 mm and a length of 400-500 mm. The fixed bed reactor can accurately control the temperature to 0.1°C, and can simulate the working environment of the adsorbent under actual working conditions, and can be used as a test device for various gas-solid reactions.

The mercury form conversion system includes a heating box and two washing bottles, the heating box is used for heating and keeping the mixed gas warm, and the two washing bottles are respectively equipped with 10% SnCl ₂ solution and 10% NaOH solution. The mercury analysis system includes a mercury analyzer (Lumex) and a general computer. The mercury detector is used to detect elemental mercury, and the measured mercury concentration curve is displayed on a computer.

The mercury generating device is installed in the _N2 gas distribution branch. The gas outlet of the gas distribution system is connected with the gas inlet of the fixed bed reactor. The gas outlet of the fixed bed reactor is connected with the gas inlet of the heating box. The gas outlet of the heating box is connected with the gas inlet of the washing bottle I containing ₁₀ % SnCl2 solution. The gas outlet of the gas washing bottle I is connected with the air inlet of the gas washing bottle II filled with 10% NaOH solution. The gas outlet of the gas washing bottle II is connected with mercury analysis equipment.

From the gas distribution system to the mercury form conversion system, the above-mentioned device conducts gas preheating and heat preservation through the electric heating belt throughout the process, so as to avoid the impact of sudden temperature drop on the mercury concentration.

During the experiment, after N ₂ flows through the mercury generating device, mercury vapor will be taken out and enter the mixed gas together. Then the mixed gas is passed into the fixed bed reactor for adsorption. In addition, the mercury analysis system marks the experimental mercury concentration baseline, and the mercury concentration at the simulated gas outlet of the test device is stable at 15ng/L±1ng before entering the reactor for detection; during the detection process, the mercury concentration at the simulated gas outlet reaches 15ng/L±1 1ng, stop the experiment.

Example 3:

Adopt the method and device described in embodiment 1 and embodiment 2 to carry out the experiment, select the charcoal-based adsorbent 50mg through vulcanization treatment, experimental test condition is as follows:

Total flow rate of mixed gas: 1L/min; fixed bed reactor temperature: 140°C; mercury concentration: 15ng/L; oxygen content: 6%; carbon dioxide content: 13.5%; NO ₂ concentration: 20ppm; NO concentration: 300ppm; SO ₂ Concentration: 300ppm; HCl concentration: 8ppm; N ₂ : carrier gas balance gas.

During the test, carbon-based adsorbents treated under different process conditions were selected (for the preparation process of various vulcanization-treated carbon-based adsorbents, please refer to the patent document No. 200810237190.3 "Sulphur-loaded activated carbon for flue gas demercury and its preparation method" Recorded) to test, VAC represents the untreated carbon-based adsorbent, AC-x-y represents the sample that has been vulcanized for y minutes under the condition of X°C.

The test method and test device were used to evaluate the mercury removal performance of different carbon-based adsorbents. The experimental results are shown in Table 1.

Table 1 Mercury adsorption capacity of different carbon-based adsorbents

The higher the content of mercury adsorbed by the adsorbent per unit mass, the better the mercury removal effect of the adsorbent.

Claims (4)

1. test a method for carbon-supported catalyst demercuration performance, it is characterized in that, comprise and prepare mixed gas, absorption, aftertreatment and testing process, described method specifically comprises the following steps:

1) be that the carbon-supported catalyst sample of 2 ~ 4mm loads in adsorptive reactor by 50mg granularity;

2) by N ₂, CO ₂, NO, NO ₂, HCl, SO ₂, and O ₂mixing, N ₂mercuryvapour is brought into mixed gas through mercury osmos tube before mixing; Obtained mixed gas is by 20ppmNO ₂, 300ppmNO, 5 ~ 10ppmHCl, 300ppmSO ₂, 6%O ₂, 13.5%CO ₂, 15 ± 1ng/L mercury and N ₂composition, wherein N ₂as balanced gas;

3) obtained mixed gas is heated to 100 ~ 150 DEG C; Then pass into adsorptive reactor, the total flow of mixed gas is 1L/min, and adsorption reaction actuator temperature is 140 DEG C;

4) through step 3) process after mixed gas pass into heating cabinet, after 100 DEG C are heated to it be incubated;

5) through step 4) process after mixed gas pass into 10%SnCl successively ₂solution and 10%NaOH solution;

6) to through step 5) mixed gas after process carries out detections analysis; Twin-beam cold-vapour atomic absorption method is adopted to measure and pass through the areal calculation mercury adsorbance between integration breakthrough curve and datum line; Its computing formula is $A=\frac{{\∫}_{c_t}^{c_0}cdt}{m}\×1/1000;$

A represents the adsorbance (μ g/g) of carbon-supported catalyst to mercury;

C ₀represent datum line mixed gas mercury concentration (ng/L);

C _trepresent mixed gas mercury concentration (ng/L) in test process;

M represents carbon-supported catalyst quality (g);

C represents the curve of mercury concentration changes with time in mixed gas.

2. a kind of method of testing carbon-supported catalyst demercuration performance according to claim 1, a kind of carbon-supported catalyst demercuration performance testing device is provided, it is characterized in that: comprise gas distributing system, mercury generating means, fixed bed reactors, mercury shape conversion system and mercury analytic system;

Described gas distributing system comprises generator and the distribution branch road of above-mentioned various gas; Described mercury generating means comprises mercury osmos tube, U-tube and thermostatical oil bath; Described mercury osmos tube is positioned at U-tube, and U-tube is positioned at thermostatical oil bath; Described fixed bed reactors and adsorptive reactor; Described mercury shape conversion system comprises heating cabinet and two Drexel bottles, and two Drexel bottles are equipped with 10%SnCl respectively ₂solution and 10%NaOH solution; Described mercury analytic system comprises mercury vapor analyzer and common computer;

Described mercury generating means is arranged on N ₂in distribution branch road; The gas outlet of described gas distributing system is connected with the air intake opening of fixed bed reactors; The gas outlet of described fixed bed reactors is connected with the air intake opening of heating cabinet; Described heating cabinet gas outlet with 10%SnCl is housed ₂the air intake opening of the Drexel bottle I of solution connects; The gas outlet of described Drexel bottle I is connected with the air intake opening of the Drexel bottle II that 10%NaOH solution is housed; The gas outlet of described Drexel bottle II is communicated with mercury analytical equipment.

3. a kind of carbon-supported catalyst demercuration performance testing device according to claim 2, is characterized in that: described fixed bed reactors can accurate temperature controlling to 0.1 DEG C, can simulate actual condition adsorbent working environment, as all kinds of gas-solid reaction proving installation.

4. a kind of carbon-supported catalyst demercuration performance testing device according to claim 2, is characterized in that: this device is from gas distributing system to mercury shape conversion system, and whole process carries out air preheat insulation by heat tape.