Online detection device for chlorine content concentration of tail gas of TiCl4 production reaction furnace and use method of online detection device

Abstract

The invention discloses an online detection device for chlorine content concentration of tail gas of a TiCl4 production reaction furnace and a use method of the online detection device. The online detection device comprises a reaction kettle, wherein a spraying device is arranged in the reaction kettle; the reaction kettle is provided with four inlets, one inlet is connected with a supersaturated salt water tank, a gas collection pump and a gas inlet in sequence, one inlet is connected with a first alkali liquor tank, one inlet is connected with a liquid meter and a second alkali liquor tank in sequence, and the other inlet is connected with a vent hole; the reaction kettle is also provided with an outlet which is connected with the waste liquid outlet; the reaction kettle is also provided with a detection port; and the detection port is sequentially connected with the online industrial acid-base tester and the control unit. The use amount of chlorine is adjusted according to the chlorine content of the tail gas of the reaction furnace, the utilization rate of chlorine is increased, and Cl2 waste and post-treatment cost increase caused by incomplete or excessive reaction due to insufficient chlorine content in the reaction kettle are avoided. And online detection of the chlorine content concentration of the tail gas of the TiCl4 production reaction furnace is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of TiCl4 production, and more specifically, to an on-line chlorine content concentration detection device for the tail gas of a TiCl4 production reactor and a method for using the same. Background Art

[0002] TiCl4 is an important chloride of titanium and is currently the raw material for the industrial production of sponge titanium (metallic titanium) and titanium dioxide by the chlorination method. The production of TiCl4 is achieved by the method of adding carbon and chlorination to titanium slag or rutile in a chlorination furnace. The chlorination process is divided into three chlorination methods: shaft furnace chlorination, molten salt chlorination, and fluidized bed chlorination. During the production process of TiCl4, in order to improve the utilization rate of chlorine gas, the chlorine concentration in the reaction vessel can be adjusted by adjusting the amount of chlorine gas entering the reactor. Therefore, a set of devices is required to measure the chlorine content concentration of the tail gas of the reactor in real time.

[0003] Chlorine gas (Cl2), as a widely used chemical raw material, is also a highly toxic gas. Excessive emission will cause poisoning of personnel and environmental pollution. There are various methods for measuring the chlorine concentration. The following are some common methods: (1) Color observation method, which can be divided into direct observation or indirect observation. Chlorine gas is a yellow-green gas, and the oxidizing property of Cl2 can also be used to change the color of test paper or test solution, such as moist starch KI test paper, FeCl2 solution, aqueous solution of hydrogen sulfide (H2S), etc. This method can only be used as a quantitative analysis method. (2) Laboratory detection methods, which are divided into two categories: chemical titration method and instrument detection method, such as gravimetric method, ion chromatography method, ultraviolet absorption spectroscopy technology, electrochemical sensor method, resistance chlorine meter method, etc. This method has high data accuracy, high sensitivity, and a wide quantitative range. The disadvantages are long detection period and large sampling workload, and it is not suitable for measuring whether the chlorine content in the ambient air exceeds the standard on-site. (3) Portable detection instruments: such as pump suction type chlorine gas detectors, portable chlorine gas leakage detectors, and on-line chlorine gas detection alarms, etc. These devices can monitor the chlorine concentration in the environment in real time. Chemical sensors have the characteristics of small volume, convenient use, and high sensitivity. Therefore, chemical sensors can be used to conveniently detect trace amounts of chlorine gas in the air at any time and anywhere. Currently, there are few sensors for detecting high concentrations.

[0004] The main components of the furnace gas escaping from the chlorination furnace are N2, O2, CO, CO2, and also contain a certain amount of low-boiling chlorides such as Cl2, HCl, SiCl4, and a small amount of uncondensed TiCl4. Currently, the main processes for absorbing and treating chlorine-containing tail gas include production of liquid chlorine method, synthesis of hydrochloric acid method, water absorption method, alkali solution absorption method, ferrous chloride absorption method, etc. The production of liquid chlorine method and the synthesis of hydrochloric acid method have the problems of high process requirements and great difficulty; the chlorine solubility of the water absorption method is limited, and the absorption efficiency of the chlorine-containing tail gas is low; the alkali solution absorption method has a high absorption efficiency.

[0005] In industrial production, a gas burette is usually used to collect the gas in the reactor for laboratory testing, which is not only time-consuming but also discontinuous. To achieve continuous measurement of gas content, frequent sampling and detection are required, which not only increases the workload of the operators but also increases their frequency of exposure to dangerous gases, thus increasing the operation risk.

[0006] Therefore, it is necessary to develop a chlorine detection equipment and method with continuous operation and high automation. In the process of producing aluminum trichloride by the boiling method, Shan Dapeng prepared a continuous analyzer using the principle of primary battery in the continuous determination of the chlorine content in the tail gas of aluminum chloride. The primary battery consists of a chlorine electrode carbon rod, a copper electrode copper rod and an aqueous solution containing chlorine, and the concentration of chlorine water is continuously determined by measuring the current. When producing chlorinated polyvinyl chloride (CPVC), Zhu Wenhui used a 15% NaOH solution by mass fraction to absorb chlorine in the tail gas in the on-line detection method of the chlorine and hydrogen chloride content in the CPVC production mixture gas, and calculated the Cl2 content through the data of the gas flowmeter to achieve the purpose of on-line detection. Summary of the Invention

[0007] The object of the present invention is to overcome the above-mentioned defects existing in the prior art, and provide an on-line detection device for the chlorine content concentration in the tail gas of a TiCl4 production reaction furnace and its use method.

[0008] To achieve the above object, the technical solution of the present invention is as follows:

[0009] An on-line detection device for the chlorine content concentration in the tail gas of a TiCl4 production reaction furnace, the detection device includes a reaction kettle 5 with a spraying device 8 arranged inside; the reaction kettle 5 is provided with four inlets, one of which is successively connected with a saturated brine tank 4, a gas collection pump 3 and an air inlet 1, one is connected with a first alkali solution tank 7, one is successively connected with a liquid meter 9 and a second alkali solution tank 11, and the other is connected with a ventilation hole 12; the reaction kettle 5 is also provided with an outlet, and the outlet is connected with a waste liquid discharge port 17; the reaction kettle 5 is also provided with a detection port, and the detection port is successively connected with an on-line industrial acid-base detector 15 and a control unit 14; the connecting pipelines between the air inlet 1 and the gas collection pump 3, between the first alkali solution tank 7 and the reaction kettle 5, between the liquid meter 9 and the second alkali solution tank 11, between the reaction kettle 5 and the ventilation hole 12 and between the reaction kettle 5 and the waste liquid discharge port 17 are provided with numerical control switches; the control unit 14 is used to control the numerical control switches.

[0010] Optionally, the first alkali solution tank 7 is used for neutralizing liquid.

[0011] Optionally, the second alkali solution tank 11 is used to absorb chlorine in the exhausted tail gas.

[0012] Optionally, a first numerical control switch 2 is provided in the connecting pipeline between the air inlet 1 and the gas collection pump 3; a second numerical control switch 6 is provided in the connecting pipeline between the first lye tank 7 and the reaction kettle 5; a third numerical control switch 10 is provided in the connecting pipeline between the liquid meter 9 and the second lye tank 11; a fourth numerical control switch 13 is provided in the connecting pipeline between the reaction kettle 5 and the ventilation hole 12; a fifth numerical control switch 16 is provided on the reaction kettle 5 and the waste liquid discharge port 17.

[0013] Optionally, the lye contained in the first lye tank 7 and the second lye tank 11 includes at least one of NaOH, Na2CO3, and Ca(OH)2.

[0014] Optionally, supersaturated brine is provided in the supersaturated brine tank 4.

[0015] Optionally, the concentration of the lye is 5% - 20%.

[0016] The present invention also discloses a use method of an on-line chlorine content concentration detection device for the tail gas of a TiCl4 production reactor as described above, including the following steps:

[0017] First step: Start the gas collection pump 3, open the first numerical control switch 2, and transport the chlorine-containing tail gas collected by the air inlet 1 to the supersaturated brine tank 4 for filtration to remove HCl gas in the chlorine-containing tail gas, and then introduce the chlorine-containing tail gas after filtering HCl into the reaction kettle 5; open the second numerical control switch 6 to exhaust the air in the reaction kettle 5. When uniform bubbles are generated in the first lye tank 7, the reaction kettle 5 is filled with chlorine-containing tail gas, and then close the first numerical control switch 2 and the second numerical control switch 6;

[0018] Second step: Start the spraying device 8 and the on-line industrial acid-base detector 15, open the third numerical control switch 10, the initial measurement value of the liquid meter is a0, and react the lye in the second lye tank 11 with the chlorine-containing tail gas in the reaction kettle 5 through the spraying device 8 to obtain a reaction liquid at the bottom of the reaction kettle 5;

[0019] Third step: When the on-line industrial acid-base detector 15 measures that the pH value of the reaction liquid is 7, immediately close the third numerical control switch 10; record the measurement value of the liquid meter at this time as a1, that is, the volume of the lye used in the reaction is a1 - a0;

[0020] Fourth step: Open the fourth numerical control switch 13, and introduce air into the reaction kettle 5 through the ventilation hole 12 to balance the internal and external air pressures of the reaction kettle 5. Open the fifth numerical control valve to drain the reaction liquid at the bottom of the reaction kettle 5 through the waste liquid discharge port 17;

[0021] Fifth step: Close the fourth numerical control switch 13 and the fifth numerical control switch 16, and repeat the first step to the fifth step;

[0022] Step 6: Record the volume of the obtained lye. If it exceeds the threshold, an alarm signal is generated to adjust the chlorine dosage in a timely manner.

[0023] Implementing the embodiments of the present invention will have the following beneficial effects:

[0024] The present invention provides an on-line chlorine content concentration detection device for the tail gas of a TiCl4 production reactor and its use method. By adjusting the chlorine dosage according to the chlorine content in the tail gas of the reactor, the utilization rate of chlorine is improved, and the incomplete reaction or excessive amount of chlorine in the reaction kettle, which causes waste of Cl2 and increases the later treatment cost, can be avoided. It can be used for real-time monitoring of the chlorine content in the tail gas during the production of chlorine-containing products. Brief Description of the Drawings

[0025] Figure 1 It is an on-line chlorine content concentration detection device for the tail gas of a TiCl4 production reactor according to an embodiment of the present invention.

[0026] Among them, 1: Inlet; 2: First numerical control switch; 3: Gas collection pump; 4: Supersaturated brine tank; 5: Reaction kettle; 6: Second numerical control switch; 7: First lye tank; 8: Spraying device; 9: Liquid meter; 10: Third numerical control switch; 11: Second lye tank; 12: Vent hole; 13: Fourth numerical control switch; 14: Control unit; 15: On-line industrial acid-base detector; 16: Fifth numerical control switch; 17: Waste liquid discharge port. Detailed Embodiments

[0027] The following further illustrates the present invention with specific embodiments, but does not limit the present invention in any way.

[0028] The present invention discloses an on-line chlorine content concentration detection device for the tail gas of a TiCl4 production reactor, as Figure 1 shown. The detection device includes a reaction kettle 5 with a spraying device 8 inside; the reaction kettle 5 has four inlets, one of which is sequentially connected to the supersaturated brine tank 4, the gas collection pump 3 and the inlet 1, one is connected to the first lye tank 7, one is sequentially connected to the liquid meter 9 and the second lye tank 11, and the other is connected to the vent hole 12; the reaction kettle 5 also has an outlet, and the outlet is connected to the waste liquid discharge port 17; the reaction kettle 5 also has a detection port, and the detection port is sequentially connected to the on-line industrial acid-base detector 15 and the control unit 14; numerical control switches are provided on the connecting pipelines between the inlet 1 and the gas collection pump 3, between the first lye tank 7 and the reaction kettle 5, between the liquid meter 9 and the second lye tank 11, between the reaction kettle 5 and the vent hole 12, and between the reaction kettle 5 and the waste liquid discharge port 17; the control unit 14 is used to control the numerical control switches.

[0029] In a specific embodiment, the first lye tank 7 is used for the neutralizing liquid.

[0030] In a specific embodiment, the second lye tank 11 is used for absorbing chlorine gas in the exhausted tail gas.

[0031] In a specific embodiment, a first numerical control switch 2 is provided in the connecting pipeline between the air inlet 1 and the gas collection pump 3; a second numerical control switch 6 is provided in the connecting pipeline between the first lye tank 7 and the reaction kettle 5; a third numerical control switch 10 is provided in the connecting pipeline between the liquid meter 9 and the second lye tank 11; a fourth numerical control switch 13 is provided in the connecting pipeline between the reaction kettle 5 and the ventilation hole 12; a fifth numerical control switch 16 is provided on the reaction kettle 5 and the waste liquid discharge port 17.

[0032] In a specific embodiment, the lye contained in the first lye tank 7 and the second lye tank 11 includes at least one of NaOH, Na2CO3, and Ca(OH)2.

[0033] In a specific embodiment, supersaturated brine is provided in the supersaturated brine tank 4.

[0034] In a specific embodiment, the concentration of the lye is 5% - 20%. Specifically, the concentration of the NaOH alkaline solution is configured according to the Cl2 concentration.

[0035] The present invention also discloses a usage method of an on-line chlorine content concentration detection device for the tail gas of a TiCl4 production reactor as described above, including the following steps:

[0036] First step: Start the gas collection pump 3, open the first numerical control switch 2, and transport the chlorinated tail gas collected at the air inlet 1 to the supersaturated brine tank 4 for filtration to remove HCl gas in the chlorinated tail gas, and then introduce the chlorinated tail gas after filtering HCl into the reaction kettle 5; open the second numerical control switch 6 to exhaust the air in the reaction kettle 5. When uniform bubbles are generated in the first lye tank 7, the reaction kettle 5 is filled with chlorinated tail gas, and then close the first numerical control switch 2 and the second numerical control switch 6;

[0037] Second step: Start the spraying device 8 and the on-line industrial acid-base detector 15, open the third numerical control switch 10, the initial measurement value of the liquid meter is a0, and react the lye in the second lye tank 11 with the chlorinated tail gas in the reaction kettle 5 through the spraying device 8 to obtain a reaction liquid at the bottom of the reaction kettle 5;

[0038] Third step: When the pH value of the reaction liquid measured by the on-line industrial acid-base detector 15 is 7, immediately close the third numerical control switch 10; record the measurement value of the liquid meter at this time as a1, that is, the volume of the lye used in the reaction is a1 - a0;

[0039] Step 4: Turn on the fourth numerical control switch 13, and deliver air into the reaction kettle 5 through the vent hole 12 to balance the internal and external air pressures of the reaction kettle 5. Then turn on the fifth numerical control valve to drain all the reaction liquid at the bottom of the reaction kettle 5 through the waste liquid discharge port 17;

[0040] Step 5: Turn off the fourth numerical control switch 13 and the fifth numerical control switch 16, and repeat Steps 1 to 5;

[0041] Step 6: Record the volume of the obtained alkali solution. If it exceeds the threshold value, an alarm signal will be generated, so as to realize the timely adjustment of the chlorine dosage.

[0042] The present invention adopts the method of using alkaline solutions such as NaOH, Na2CO3, and Ca(OH)2 as absorbents to absorb chlorine. Through the neutralization reaction of chlorine with liquid alkali to generate chlorides and hypochlorites, the purpose of complete absorption is achieved, that is, the alkaline solution neutralization method. Taking NaOH as an example, the reaction formula is as follows:

[0043] Cl2 + 2NaOH → NaClO + NaCl + H2O (1)

[0044] When the volume and the concentration of NaOH are constant, it can be known from formula (1) that the concentration of Cl2 is directly proportional to the volume of the NaOH liquid. That is, the concentration of Cl2 can be calculated by measuring the volume of the used NaOH liquid.

[0045] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of this invention patent shall be subject to the appended claims.

Claims

1. An online detection device for the chlorine content concentration of tail gas from a TiCl4 production reactor, characterized in that: The detection device comprises a reaction kettle (5) having a spray device (8) disposed therein; The reactor (5) is provided with four inlets, one of which is connected to the supersaturated salt water tank (4), the gas collection pump (3) and the air inlet (1) in sequence, one is connected to the first alkali liquid tank (7), one is connected to the liquid meter (9) and the second alkali liquid tank (11) in sequence, and the other is connected to the vent hole (12); The reactor (5) is also provided with an outlet, which is connected to the waste liquid discharge outlet (17); The reaction kettle (5) is also provided with a detection port, which is sequentially connected to an online industrial acid-base tester (15) and a control unit (14); A connecting pipeline between the air inlet (1) and the gas collection pump (3), a connecting pipeline between the first alkali liquid tank (7) and the reactor (5), a connecting pipeline between the liquid meter (9) and the second alkali liquid tank (11), a connecting pipeline between the reactor (5) and the vent (12), and a connecting pipeline between the reactor (5) and the waste liquid outlet (17) are provided with a numerical control switch; The control unit (14) is used to control the digital control switch.

2. The online detection device for the chlorine content concentration of tail gas of the TiCl4 production reactor according to claim 1, characterized in that: The first alkali liquid tank (7) is used for neutralizing liquid; The second alkali liquid tank (11) is used to absorb chlorine in the exhaust tail gas.

3. According to the online detection device for the chlorine content concentration of tail gas of the TiCl4 production reactor of claim 1, the connecting pipeline between the air inlet (1) and the gas collection pump (3) is provided with a first digital control switch (2); The connecting pipeline between the first alkali liquid tank (7) and the reaction kettle (5) is provided with a second numerical control switch (6); The connecting pipeline between the liquid meter (9) and the second alkali liquid tank (11) is provided with a third digital control switch (10); The connecting pipeline between the reaction kettle (5) and the vent hole (12) is provided with a fourth digital control switch (13); A fifth numerically controlled switch (16) is provided on the reaction kettle (5) and the waste liquid discharge port (17).

4. According to the online detection device for the chlorine content concentration of the tail gas of the TiCl4 production reactor of claim 1, the alkali liquid contained in the first alkali liquid tank (7) and the second alkali liquid tank (11) includes at least one of NaOH, Na2CO3, and Ca(OH)2.

5. The online detection device for the chlorine content concentration of tail gas of the TiCl4 production reactor according to claim 1, wherein the supersaturated salt water tank (4) is provided with supersaturated salt water.

6. The on-line detection device for the chlorine content concentration in tail gas of a TiCl4 production reactor according to claim 1, wherein the concentration of the alkali solution is 5% to 20%.

7. A method for using the online detection device for the chlorine content concentration of tail gas of a TiCl4 production reactor as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: The first step is to start the gas collection pump (3), open the first numerical control switch (2), and convey the chlorinated tail gas collected by the air inlet (1) to the supersaturated salt water tank (4) for filtration to remove HCl gas in the chlorinated tail gas, and then pass the chlorinated tail gas after HCl is filtered into the reaction kettle (5); The second numerical control switch (6) is opened to remove the air in the reaction kettle (5); when the first alkali liquid tank (7) generates uniform bubbles, the reaction kettle (5) is filled with chlorinated tail gas, and then the first numerical control switch (2) and the second numerical control switch (6) are closed; Step 2: start the spray device (8) and the online industrial acid-base tester (15), turn on the third numerical control switch (10), the initial metering value of the liquid meter is a0, and the alkali liquid in the second alkali liquid tank (11) reacts with the chlorinated tail gas in the reactor (5) through the spray device (8), and obtains a reaction liquid at the bottom of the reactor (5); Step 3: When the online industrial acid-base tester (15) measures the pH value of the reaction liquid to be 7, immediately close the third digital control switch (10); record the measured value of the liquid meter at this time as a1, that is, the volume of the alkali solution shared by the reaction is a1-a0; Step 4: Open the fourth numerical control switch (13) to deliver air into the reaction kettle (5) through the vent hole (12) to balance the internal and external air pressures of the reaction kettle (5), and open the fifth numerical control valve to drain the reaction liquid at the bottom of the reaction kettle (5) through the waste liquid discharge port (17); Step 5: Close the fourth digital switch (13) and the fifth digital switch (16), and repeat the first step. Step 5; Step 6: The volume of the alkali solution obtained is recorded. If it exceeds the threshold, an alarm signal is generated, thereby achieving timely adjustment of the amount of chlorine.

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