A three-phase water film cold washing purification process and device for yellow phosphorus electric furnace tail gas

Abstract

The present invention discloses a three-phase water film cold washing purification process and device for yellow phosphorus electric furnace tail gas, belonging to the technical field of yellow phosphorus tail gas purification. The present invention solves the problem that yellow phosphorus tail gas is easy to clog the pipe. The present invention passes the yellow phosphorus tail gas into a cooler that realizes cooling by heat exchange with cooling water, so that the yellow phosphorus in the yellow phosphorus tail gas condenses in the heat exchange channel; when the purification time reaches the set time, the cooling of the cooling water is stopped, and cold washing liquid is sprayed into the heat exchange channel, so that the cold washing liquid replaces the cooling water to perform heat exchange with the yellow phosphorus tail gas, so that the yellow phosphorus at the innermost side of the heat exchange channel is melted, and the cold washing liquid can flush the condensed yellow phosphorus in the heat exchange channel. The technical solution of the present invention not only greatly improves the removal effect when removing yellow phosphorus in the shell and tube cooler, but also the removal rate of yellow phosphorus in the yellow phosphorus tail gas can be maintained at more than 70%.

Description

Technical Field

[0001] The invention belongs to the technical field of yellow phosphorus tail gas purification, and in particular relates to a three-phase water film cold washing purification process and a device for yellow phosphorus electric furnace tail gas. Background Art

[0002] The electric furnace is the primary equipment for yellow phosphorus production. Qualified phosphate rock, silica, and coke are mixed in a specific ratio and then added to the furnace. A reduction reaction occurs at 1300-1500°C. The resulting phosphorus-containing furnace gas undergoes dust removal, condensation, and refining to produce finished yellow phosphorus. Byproducts, slag and ferrophosphorus, are regularly discharged from the furnace bottom. Consequently, stringent requirements are placed on the insulation and refractory materials used in the furnace lining, as well as the refractory brick structure.

[0003] The exhaust gas from an electric furnace typically has a temperature of around 57°C and contains components such as CO, H₂, elemental phosphorus (P₄), sulfur compounds, PH₃, and dust. Since yellow phosphorus exhaust gas carries phosphorus and dust, it tends to adhere to the tubes due to the drop in temperature as it passes through them. This, on the one hand, results in significant phosphorus loss, making it unrecoverable, and on the other hand, the adhered phosphorus accumulates over time, leading to clogging. Therefore, a technical solution to this problem is necessary. Summary of the Invention

[0004] In view of the problems in the prior art that phosphorus and dust are entrained in yellow phosphorus tail gas, and are easily attached to the tube side due to the decrease in temperature when passing through the tube side, on the one hand, causing a large amount of phosphorus to be lost and unable to be recovered, and on the other hand, the phosphorus and dust attached to the tube side will become thicker and thicker over time, thereby clogging the tube side, the present invention provides a three-phase water film cold washing purification process and device for yellow phosphorus electric furnace tail gas.

[0005] The technical solution adopted in the present invention is as follows:

[0006] A three-phase water film cold washing purification process for yellow phosphorus electric furnace tail gas comprises the following steps:

[0007] Step 1: passing the yellow phosphorus tail gas into a cooler that is cooled by exchanging heat with cooling water to reduce the temperature of the yellow phosphorus tail gas, thereby condensing the yellow phosphorus in the yellow phosphorus tail gas in the heat exchange channel. The purified yellow phosphorus tail gas is discharged from the cooler, and the temperature of the cooling water is maintained at the cooling temperature during the purification process;

[0008] Step 2: When the purification time reaches the set time, the cooling water is stopped from being cooled, and the temperature of the cooling water is detected in real time. When the cooling water temperature rises to the melting point of yellow phosphorus due to the heat exchange temperature with the yellow phosphorus tail gas, a cold washing liquid with a temperature lower than that of the yellow phosphorus tail gas is sprayed into the heat exchange channel, so that the cold washing liquid and the yellow phosphorus tail gas pass through the heat exchange channel from top to bottom in the same direction. The cold washing liquid replaces the cooling water and continues to exchange heat with the subsequent yellow phosphorus tail gas, thereby achieving continuous purification of the yellow phosphorus tail gas. At the same time, the cold washing liquid entering the heat exchange channel forms a water curtain along the side wall of the heat exchange channel, thereby flushing the condensed yellow phosphorus in the heat exchange channel;

[0009] Step 3: After the cold wash liquid is turned on for the set time, the cooling water is cooled until the cooling water temperature drops to the set cooling temperature, and then the cold wash liquid is stopped, so that the cooling water replaces the cold wash liquid and continues to exchange heat with the subsequent yellow phosphorus tail gas;

[0010] Repeat steps 1-3 to achieve continuous purification of yellow phosphorus tail gas.

[0011] After adopting this technical solution, the present invention first performs heat exchange with the yellow phosphorus tail gas through the cooling water in the cooler, thereby reducing the temperature of the yellow phosphorus tail gas, thereby causing the yellow phosphorus in the yellow phosphorus tail gas to condense on the side walls of the heat exchange channel, so as to achieve the effect of separating the phosphorus in the yellow phosphorus tail gas and prevent it from condensing in the pipe path and clogging the pipeline in the subsequent process. After a certain thickness of yellow phosphorus has condensed, the cooling water is stopped, and the temperature of the cooling water is gradually increased until it reaches the melting point of yellow phosphorus. The cooling water that reaches the melting point of yellow phosphorus performs heat exchange with the yellow phosphorus adhering to the side walls of the heat exchange channel, melting the yellow phosphorus at the innermost part of the heat exchange channel, thereby loosening the connection between the yellow phosphorus and the heat exchange channel, and even automatically detaching from the side walls of the heat exchange channel under its own gravity. At this time, since cold washing liquid is also introduced, the introduced cold washing liquid also flushes the yellow phosphorus remaining on the side walls of the heat exchange channel. In this way, the yellow phosphorus in the heat exchange channel is thoroughly cleaned by heating and water flushing, thereby achieving full recovery of the yellow phosphorus. After the cooling water temperature rises, the cold washing liquid introduced replaces the cooling water and continues to exchange heat with the yellow phosphorus tail gas, thereby continuously cooling and purifying the yellow phosphorus tail gas.

[0012] Preferably, in step 2, spraying of the cold wash liquid is started 5-10 seconds after the temperature of the cooling water reaches the melting point of yellow phosphorus.

[0013] After adopting this technical solution, since the sprayed cold washing liquid will also exchange heat with the cooling water, resulting in heat loss of the cooling water, the cold washing liquid is sprayed 5-10 seconds after the cooling water temperature reaches the melting point of yellow phosphorus. This ensures that the heated cooling water has enough time to exchange heat with the yellow phosphorus adhering to the heat exchange channel to ensure the separation effect, while also avoiding affecting the subsequent purification of yellow phosphorus tail gas.

[0014] Preferably, the temperature of the cold wash liquid is 40-45° C., the pressure is normal pressure, the gas-liquid volume ratio is 140-160:1, and the gas flow rate is 4-6 m / s.

[0015] After adopting this technical solution, the cold washing liquid and the yellow phosphorus electric furnace exhaust gas pass through the water film cold washing heat exchange tube in the cooler from top to bottom in the same direction, which not only ensures the heat and mass transfer between the gas and liquid, but also ensures that the yellow phosphorus and dust dissolved in the cold washing liquid do not clog the water film cold washing heat exchange tube; the cooling water flows from bottom to top in the shell side of the cooler, ensuring the heat exchange efficiency.

[0016] A three-phase water film cold washing purification device for yellow phosphorus electric furnace tail gas that realizes a three-phase water film cold washing purification process for yellow phosphorus electric furnace tail gas, comprising a shell and tube cooler, the shell and tube cooler comprising an air inlet, an exhaust port, a cooling water inlet, and a cooling water outlet, the air inlet being arranged at the upper portion of the shell and tube cooler, and the air inlet being connected to an air inlet pipe and a cold washing liquid supply pipe, the exhaust port being arranged at the lower portion of the shell and tube cooler, a tee being arranged at the exhaust port, one end of the tee being connected to the exhaust port, and the other two ends being respectively connected to a drain pipe and an exhaust pipe, an induced draft fan being arranged on the exhaust pipe, and the drain pipe being connected to a cold washing liquid pool.

[0017] Preferably, the cold washing liquid pool is connected to a cold washing nozzle arranged in the cooler through a cold washing liquid supply pipe, and a cold washing liquid pump is provided on the cold washing liquid supply pipe.

[0018] After adopting this technical solution, the washed yellow phosphorus reaches the cold washing liquid pool from the drainage pipe for precipitation. The yellow phosphorus is precipitated in the lower part of the cold washing liquid pool, and the upper clear liquid side can be retained as the cold washing liquid for the next cold washing, so as to save water.

[0019] Preferably, the cooling water inlet is connected to one end of a cooling water supply pipe, the other end of the cooling water supply pipe is connected to the cooling water outlet, and the cooling water supply pipe is arranged in a circulating water cooling tower.

[0020] After adopting this technical solution, the cooling water is cooled and circulated through the circulating water cooling tower before being recycled to reduce water consumption.

[0021] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0022] 1. The present invention first performs heat exchange with the yellow phosphorus tail gas through cooling water in the cooler to reduce the temperature of the yellow phosphorus tail gas, thereby causing the yellow phosphorus in the yellow phosphorus tail gas to condense on the side wall of the heat exchange channel, thereby achieving the effect of separating the phosphorus in the yellow phosphorus tail gas and preventing it from condensing in the pipe path and clogging the pipe in the subsequent process.

[0023] 2. In the present invention, when a certain thickness of yellow phosphorus has condensed, the cooling of the cooling water is stopped, and the temperature of the cooling water is gradually increased until it reaches the melting point of the yellow phosphorus. The cooling water that has reached the melting point of the yellow phosphorus exchanges heat with the yellow phosphorus adhering to the side walls of the heat exchange channel, melting the yellow phosphorus at the innermost side of the heat exchange channel, thereby loosening the connection between the yellow phosphorus and the heat exchange channel, and even automatically detaching from the side walls of the heat exchange channel under its own gravity. At this time, since cold washing liquid is also introduced, the introduced cold washing liquid also flushes the yellow phosphorus remaining on the side walls of the heat exchange channel. In this way, the yellow phosphorus in the heat exchange channel is thoroughly cleaned by heating and water flushing, thereby achieving full recovery of the yellow phosphorus.

[0024] 3. In the present invention, the cold wash liquid introduced after the cooling water temperature rises replaces the cooling water to continue to perform heat exchange with the yellow phosphorus tail gas, thereby continuously cooling and purifying the yellow phosphorus tail gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the present invention;

[0026] Among them, 1-shell and tube cooler, 2-induced air fan, 3-cold wash nozzle, 4-cold wash liquid pump, 5-cold wash liquid pool, 6-circulating water cooling tower. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application.

[0028] In the description of the embodiments of the present application, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, or are the orientation or positional relationship in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, they cannot be understood as limiting the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0029] Example 1

[0030] like Figure 1 As shown, a three-phase water film cold washing purification device for yellow phosphorus electric furnace tail gas includes a shell and tube cooler 1, the cooler includes an air inlet, an exhaust port, a cooling water inlet and a cooling water outlet, the air inlet is arranged at the upper part of the cooler, and the air inlet is connected to the air inlet pipe and the cold washing liquid supply pipe, the exhaust port is arranged at the lower part of the cooler, and a tee is provided at the exhaust port, one end of the tee is connected to the exhaust port, and the other two ends are respectively connected to the drain pipe and the exhaust pipe, the exhaust pipe is provided with an induced draft fan 2, and the drain pipe is connected to the cold washing liquid pool 5.

[0031] In this embodiment, the cold wash liquid pool 5 is connected to the cold wash nozzle 3 disposed within the shell-and-tube cooler 1 via a cold wash liquid supply pipe. A cold wash liquid pump 4 is provided on the cold wash liquid supply pipe. The yellow phosphorus flushed from the cold wash liquid pool 5 flows through the drain pipe and settles in the lower portion of the cold wash liquid pool 5. The supernatant liquid can be retained as cold wash liquid for the next cold wash, thereby conserving water. The cold washing liquid supply pipe is also connected to the cold washing liquid supply tank, and the cold washing liquid supply tank is also provided with an electric heater and an electric refrigerator. The temperature of the cold washing liquid in the cold washing liquid supply tank can be regulated by the cooperation of the electric heater and the electric refrigerator. An electric valve and a pump body are provided on the pipeline connecting the cold washing liquid supply tank and the cold washing liquid supply pipe and on the pipeline connecting the cold washing liquid pool 5 and the cold washing liquid supply pipe. Temperature sensors are provided in the cold washing liquid pool 5 and the cold washing liquid supply tank, and the temperature in the cold washing liquid pool 5 and the cold washing liquid supply tank is fed back through the temperature sensor. A liquid level gauge is also provided in the cold washing liquid pool 5. When the water amount and temperature in the cold washing liquid pool 5 are not enough to meet the use requirements, the amount of cold washing liquid transported from the cold washing liquid pool 5 and the cold washing liquid supply tank to the cold washing liquid supply pipe can be regulated to realize the delivery of a fixed amount of cold washing liquid at a constant temperature to the cold washing liquid supply pipe.

[0032] In this embodiment, the cooling water inlet is connected to one end of a cooling water supply pipe, the other end of which is connected to a cooling water outlet, and the cooling water supply pipe is disposed in a circulating water cooling tower 6. The cooling water inlet is connected to one end of a cooling water supply pipe, the other end of which is connected to a cooling water outlet, and the cooling water supply pipe is disposed in a circulating water cooling tower 6.

[0033] The device can be installed at any position in the tail gas purification line according to actual purification needs.

[0034] Example 2

[0035] A three-phase water film cold washing purification process for yellow phosphorus electric furnace tail gas, which is carried out using the three-phase water film cold washing purification device for yellow phosphorus electric furnace tail gas of Example 1, comprises the following steps:

[0036] Step 1: passing the yellow phosphorus tail gas into a shell-and-tube cooler, and continuously passing cooling water at a temperature of 25° C. into the shell-and-tube cooler, so that the yellow phosphorus tail gas and the cooling water perform heat exchange, thereby reducing the temperature of the yellow phosphorus tail gas, thereby condensing the yellow phosphorus in the yellow phosphorus tail gas in the heat exchange channel. The purified yellow phosphorus tail gas is discharged from the cooler and enters the next process. During the purification process, the temperature of the cooling water is maintained at a cooling temperature by a circulating water cooling tower 6;

[0037] Step 2: When the purification time reaches 1 hour, stop cooling the cooling water and detect the temperature of the cooling water in real time. When the cooling water temperature rises to the melting point of yellow phosphorus due to heat exchange with the yellow phosphorus tail gas for 5 seconds, spray a cold wash liquid (water) at a temperature of 40°C into the heat exchange channel at normal pressure, a gas-liquid volume ratio of 150:1, and a gas flow rate of 5 m / s. The cold wash liquid and the yellow phosphorus tail gas are passed through the heat exchange channel from top to bottom in the same direction. The cold wash liquid replaces the cooling water and continues to exchange heat with the subsequent yellow phosphorus tail gas, thereby achieving continuous purification of the yellow phosphorus tail gas. At the same time, the cold wash liquid entering the heat exchange channel forms a water curtain along the side wall of the heat exchange channel, thereby flushing the condensed yellow phosphorus in the heat exchange channel.

[0038] Step 3: 10 minutes after the cold wash liquid is started, the circulating water cooling tower 6 is started to cool the cooling water until the cooling water temperature drops to the set cooling temperature, and then the cold wash liquid is stopped, so that the cooling water replaces the cold wash liquid and continues to exchange heat with the subsequent yellow phosphorus tail gas;

[0039] Repeat steps 1-3 to achieve continuous purification of yellow phosphorus tail gas.

[0040] Example 3

[0041] This embodiment is basically the same as embodiment 2, except that: after the cooling water temperature rises to the melting point of yellow phosphorus due to heat exchange with the yellow phosphorus tail gas for 8 seconds, a cold washing liquid with a temperature lower than the temperature of the yellow phosphorus tail gas is sprayed into the heat exchange channel.

[0042] Example 4

[0043] This embodiment is basically the same as embodiment 2, except that: after the cooling water temperature rises to the melting point of yellow phosphorus due to heat exchange with the yellow phosphorus tail gas for 10 seconds, a cold washing liquid with a temperature lower than the temperature of the yellow phosphorus tail gas is sprayed into the heat exchange channel.

[0044] Example 5

[0045] This embodiment is basically the same as embodiment 2, except that the temperature of the cold wash liquid is 45°C.

[0046] Example 6

[0047] This embodiment is basically the same as embodiment 2, except that the cooling water temperature is 30°C.

[0048] Comparative Example 1

[0049] This comparative example is basically the same as Example 2, except that: in this comparative example, the cooling of the cooling water is not stopped, so that the temperature of the cooling water is always maintained at 25°C.

[0050] Comparative Example 2

[0051] This comparative example is basically the same as Example 2, except that: in this comparative example, the cooling of the cooling water is not stopped, so that the temperature of the cooling water is always maintained at 25°C, and the temperature of the cold wash liquid introduced is 25°C.

[0052] Comparative Example 3

[0053] This comparative example is basically the same as Example 2, except that the temperature of the cold wash liquid introduced is 25°C.

[0054] The phosphorus content in the yellow phosphorus tail gas before and after treatment and the residual amount of yellow phosphorus in the heat exchange channel in Examples 2-6 and Comparative Examples 1-3 were detected, wherein the residual amount of yellow phosphorus was detected after the system had been working continuously for ten days. The phosphorus content and dust content in the treated yellow phosphorus tail gas were obtained by collecting the treated yellow phosphorus tail gas obtained by the system for three consecutive hours, and then the phosphorus content and dust content in the collected treated yellow phosphorus tail gas were detected. The phosphorus content and dust content of the tail gas for three consecutive days were obtained in the same way, and the data described in Table 1 were obtained by averaging the three groups of data. The yellow phosphorus tail gas introduced into the system came from the gas collecting tank, and the phosphorus content and dust content in the yellow phosphorus tail gas in the gas collecting tank were detected before the yellow phosphorus tail gas in the gas collecting tank was introduced into the system. The specific results are shown in Table 1:

[0055] Table 1

[0056]

[0057] As can be seen from Table 1, when the technical solution of the present invention is used to remove yellow phosphorus in the shell and tube cooler, not only the removal effect is greatly improved, but also the removal rate of yellow phosphorus in the yellow phosphorus tail gas can be maintained at more than 70%.

[0058] The above-described embodiments merely represent specific implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of protection of the present application. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the technical concept of the present application, and all such variations and improvements fall within the scope of protection of the present application.

Claims

1. A three-phase water film cold washing purification process for yellow phosphorus electric furnace tail gas, characterized by: The following steps are involved: Step 1: The yellow phosphorus tail gas is passed through a cooler that is cooled by heat exchange with cooling water to reduce the temperature of the yellow phosphorus tail gas, thereby condensing the yellow phosphorus in the yellow phosphorus tail gas in the heat exchange channel. The purified yellow phosphorus tail gas is discharged from the cooler. During the purification process, the temperature of the cooling water is maintained at 25-30°C. Step 2: When the purification time reaches the set time, stop cooling the cooling water and detect the temperature of the cooling water in real time. When the cooling water temperature rises to the melting point of yellow phosphorus due to heat exchange with the yellow phosphorus tail gas, 5-10 seconds later, a cold washing liquid with a temperature lower than the temperature of the yellow phosphorus tail gas is sprayed into the heat exchange channel, so that the cold washing liquid and the yellow phosphorus tail gas pass through the heat exchange channel from top to bottom in the same direction. The temperature of the cold washing liquid is 40-45°C, the pressure is normal pressure, the gas-liquid volume ratio is 140-160:1, and the gas flow rate is 4-6m / s. The cold washing liquid replaces the cooling water and continues to exchange heat with the subsequent yellow phosphorus tail gas, thereby achieving continuous purification of the yellow phosphorus tail gas. At the same time, the cold washing liquid entering the heat exchange channel forms a water curtain along the side wall of the heat exchange channel, thereby flushing the condensed yellow phosphorus in the heat exchange channel; Step 3: After the cold wash liquid is turned on for the set time, the cooling water is cooled until the cooling water temperature drops to the set cooling temperature, and then the cold wash liquid is stopped, so that the cooling water replaces the cold wash liquid and continues to exchange heat with the subsequent yellow phosphorus tail gas; Repeat steps 1-3 to achieve continuous purification of yellow phosphorus tail gas.

2. A three-phase water film cold washing purification device for yellow phosphorus electric furnace tail gas, which realizes the three-phase water film cold washing purification process for yellow phosphorus electric furnace tail gas according to claim 1, characterized in that: The invention comprises a shell and tube cooler (1), wherein the shell and tube cooler (1) comprises an air inlet, an exhaust port, a cooling water inlet, and a cooling water outlet, wherein the air inlet is arranged at the upper portion of the shell and tube cooler (1), and the air inlet is connected to an air inlet pipe and a cold washing liquid supply pipe, wherein the exhaust port is arranged at the lower portion of the shell and tube cooler (1), and a tee is arranged at the exhaust port, wherein one end of the tee is connected to the exhaust port, and the other two ends are respectively connected to a drain pipe and an exhaust pipe, wherein an induced air fan (2) is arranged on the exhaust pipe, and the drain pipe is connected to a cold washing liquid pool (5).

3. The three-phase water film cold washing purification device for yellow phosphorus electric furnace tail gas according to claim 2, characterized in that: The cold wash liquid pool (5) is connected to a cold wash nozzle (3) arranged in the cooler via a cold wash liquid supply pipe, and a cold wash liquid pump (4) is provided on the cold wash liquid supply pipe.

4. The three-phase water film cold washing purification device for yellow phosphorus electric furnace tail gas according to claim 2, characterized in that: The cooling water inlet is connected to one end of a cooling water supply pipe, the other end of the cooling water supply pipe is connected to a cooling water outlet, and the cooling water supply pipe is arranged in a circulating water cooling tower (6).

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