A process for preventing catalyst surface from agglomerating

Abstract

The invention relates to a process method for preventing catalyst surface agglomeration, and belongs to the technical field of smelting production. The process comprises the following steps: heating a conversion process, turning on an SO2 blower to assist in heating, maintaining a slight negative pressure at a first-level power wave inlet, turning on an electric furnace to control the heating rate according to a heating curve, then feeding the material for production, controlling the initial feeding amount at 30 t / h, increasing the speed of the SO2 blower, maintaining the first-level power wave inlet pressure between -0.1 and -0.5 kPa, adjusting the opening of a 1# cold shock valve to 60-95%, increasing the number of electric furnace groups, and maintaining the surface temperature of a first-layer catalyst in the conversion process between 390 and 410°C. The process can achieve the purpose of preventing the surface of a second-layer catalyst from agglomerating, reducing the low-temperature period of the second-layer catalyst from 6 hours to less than 3 hours, effectively preventing SO3 from condensing into acid mist under low-temperature conditions, clogging micropores in the catalyst, and even agglomerating the surface of the catalyst, obstructing the normal circulation of flue gas, and significantly increasing the pressure difference in the catalyst layer, thereby affecting the normal production load and, in severe cases, causing the system to be paralyzed and unable to produce normally.

Description

Technical Field

[0001] The invention relates to a process for preventing catalyst surface from agglomerating, and belongs to the technical field of smelting production. Background Art

[0002] The smelting flue gas acid conversion process adopts the III→I→IV→II conversion heat exchange process. During normal production, the heat to maintain the catalyst layer of the conversion system above the ignition temperature comes from the catalytic oxidation exothermic reaction of SO2 to SO3. The self-heating balance of the entire system is achieved through heat exchange between the higher temperature SO3 flue gas and the lower temperature SO2 flue gas.

[0003] Before the production system resumed production, due to the low overall temperature of the conversion system, electric heating furnaces were installed on the first and fourth layers of the converter. By turning on the electric heating furnaces to heat the air and raise the temperature of the conversion system, the temperature of the first and fourth layers of the converter catalyst layer was raised to the catalyst ignition temperature requirement of 390°C or above. Only then could the smelting system be unloaded for production. The initial production load was increased gradually from 30% of the normal production load based on the control of the conversion temperature. According to the original operating method, by controlling the surface temperature of the first and fourth layers of the conversion catalyst at 390-400°C, the fan speed was adjusted based on the control of the first-level power wave inlet pressure at -0.2-0.3KPa. At the same time, the heating furnaces were gradually shut down, and the opening of the conversion 1# cold shock valve was 30% per shift to ensure the temperature of the first layer of catalyst. According to this method, the second and third conversion layers usually wait until the temperature of the first and fourth conversion layers is raised, and then the interlayer temperature is raised through heat exchange. The surface layer of the second conversion layer reaches 430℃ (the second layer is a high-temperature catalyst with a higher ignition temperature). The ignition temperature takes about 6 hours after resumption of production, and the staged conversion rate of the first catalyst can reach about 70%. During this period, a large amount of SO3 flue gas enters the rear catalyst layer, which is easily condensed into acid mist under low temperature conditions, blocking the micropores of the catalyst, causing the catalyst surface to agglomerate, and the catalyst layer pressure drop to increase. In severe cases, the catalyst layer pressure drop increases from 2KPa to 8KPa, affecting the system's exhaust volume and even causing the production system to fail to operate normally, affecting the system's production operation rate, and is not conducive to production cost control. Summary of the Invention

[0004] In order to solve the above problems, the present invention can achieve the purpose of avoiding the agglomeration of the surface layer of the second-layer catalyst for conversion, and reduce the low-temperature period of the second-layer catalyst for conversion from 6 hours to less than 3 hours, effectively preventing SO3 from condensing into acid mist under low-temperature conditions, clogging the micropores of the catalyst, and even agglomerating the surface of the catalyst, obstructing the normal circulation of flue gas, and significantly increasing the pressure difference of the catalyst layer, affecting the normal production load, and in severe cases causing the system to be paralyzed and unable to produce normally.

[0005] To achieve the above object, the present invention is implemented according to the following technical solutions:

[0006] The process for preventing catalyst surface agglomeration specifically comprises the following steps:

[0007] Step 1) The temperature of the conversion process is raised. The SO2 fan is turned on to assist in the temperature increase. The first-stage power wave inlet maintains a slight negative pressure. The electric furnace is turned on and the temperature increase rate is controlled according to the temperature increase curve.

[0008] Step 2) For production, the initial feed rate is controlled at 30t / h. The SO2 blower speed is increased, and the inlet pressure of the first-stage power wave is maintained between -0.1 and -0.5kPa. The opening of the 1# cold shock valve is adjusted to 60-95%. The number of electric furnace groups is increased to maintain the surface temperature of the catalyst layer between 390-410℃.

[0009] Step 3) After the temperature between the catalyst layers continues to rise, the amount of material discharged from the smelting furnace is gradually increased, and the fan speed is increased at the same time as the temperature between the layers continues to rise;

[0010] Step 4) When the temperature between the catalyst layers of the first conversion layer rises to above 580°C, the reflux valve is opened to prevent a sudden increase in flow. The reflux valve opening is adjusted to control the pressure at the first-stage power wave inlet to a negative pressure state. The opening of the 1# cold shock valve is maintained at 95%. All 1# electric furnaces are opened, and the smelting furnace discharge rate is gradually increased to 80t / h. Under this state, the surface temperature of the catalyst layer of the second conversion layer rises to above 430°C within 1 hour. After the second conversion layer reaches the catalytic reaction conditions, the temperature of the second layer rises steadily;

[0011] Step 5) When the temperature between the two catalyst layers rises to 450°C, the smelting furnace can gradually increase the material feeding rate to full capacity and gradually shut down the furnace;

[0012] Step 6) The overall temperature is converted to the normal production range, and the first-stage power wave inlet pressure is restored to a slightly negative pressure for production.

[0013] Preferably, in step 1), the heating rate of the electric furnace is controlled within 30°C / h, and the opening of the 1# cold shock valve is maintained at 40-60%.

[0014] Preferably, the prerequisite for the blanking production in step 2) is that the surface temperature of the converted one-layer and four-layer catalysts reaches 390-410°C.

[0015] Preferably, in step 3), when the interlayer temperature rises to about 460°C, the discharge rate of the smelting furnace is increased to 40t / h; when the interlayer temperature rises to about 510°C, the discharge rate of the smelting furnace is increased to 50t / h; when the interlayer temperature rises to about 550°C, the discharge rate of the smelting furnace is increased to 60t / h. During this period, the SO2 blower speed is gradually increased to 22HZ.

[0016] Preferably, in step 4), when the temperature between the catalyst layers of the conversion layer rises to above 580° C., the fan speed is quickly increased to above 38 Hz.

[0017] Preferably, in step 4), the inlet pressure of the first-stage power wave is between -0.5 and -1.0 KPa.

[0018] Beneficial effects of the present invention:

[0019] The present invention can achieve the purpose of avoiding the agglomeration of the surface layer of the second-layer catalyst during conversion, and reduce the low-temperature period of the second-layer catalyst during conversion from 6 hours to less than 3 hours, effectively preventing SO3 from condensing into acid mist under low-temperature conditions, clogging the micropores of the catalyst, and even agglomerating the surface of the catalyst, obstructing the normal circulation of flue gas, and significantly increasing the pressure difference of the catalyst layer, affecting the normal production load, and in severe cases causing the system to be paralyzed and unable to produce normally; effectively extending the service life of the catalyst, reducing production input, and at the same time providing guarantee for the long-term stable operation of the enterprise, effectively improving the profitability of the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions and beneficial effects of the present invention clearer, preferred embodiments of the present invention will be described in detail below to facilitate understanding by technicians.

[0022] Before the smelting furnace starts to discharge materials for production, the conversion process is to carry out temperature raising operation. According to our company's process configuration, the surface temperature of the first and fourth layers of catalysts needs to be raised to 390-410℃ before production conditions are met.

[0023] During the temperature rise period of the conversion process, the SO2 fan speed is maintained at 18HZ for temperature rise, and the first-level power wave inlet is maintained at a slight negative pressure. The electric furnace is turned on and the temperature rise rate is controlled according to the temperature rise curve. In case of temperature rise after a short-term shutdown, the overall temperature of the conversion process is relatively high, and the temperature rise rate is controlled within 30℃ / h. On the premise that the outlet temperature of the 1# electric furnace does not exceed 550℃, the number of electric furnace groups is increased, and the opening of the 1# cold shock valve is maintained at 40-60%. While increasing the surface temperature of the catalyst in the first conversion layer, the overall temperature of the second conversion layer is indirectly increased.

[0024] When the surface temperature of the first and fourth layers of the conversion catalyst reaches 390-410℃, notify the smelting furnace to start unloading production, and control the initial unloading rate at 30t / h (the maximum production load of the smelting furnace is 110t / h of unloading rate). Appropriately increase the SO2 blower speed, maintain the first-level power wave inlet pressure between -0.1 and -0.5KPa, adjust the opening of the 1# cold shock valve to 60-95%, and increase the number of electric furnace groups to maintain the surface temperature of the first layer of the conversion catalyst between 390-410℃.

[0025] Because the conversion of SO2 to SO3 is an exothermic reaction, the temperature between the catalyst layers will continue to rise. When the interlayer temperature rises to about 460℃, the discharge rate of the smelting furnace is increased to 40t / h. When the interlayer temperature rises to about 510℃, the discharge rate of the smelting furnace is increased to 50t / h. When the interlayer temperature rises to about 550℃, the discharge rate of the smelting furnace is increased to 60t / h. During this period, the SO2 fan speed is gradually increased to 22HZ.

[0026] When the temperature between the catalyst layers of the first conversion layer rises to above 580℃, in order to avoid the surge period of the SO2 fan, the fan speed needs to be quickly increased to above 38HZ. At this time, the return valve needs to be opened while increasing the fan speed to avoid a sudden increase in flow. The return valve opening is adjusted to control the inlet pressure of the first-level power wave between -0.5 and -1.0 KPa. After the SO2 fan speed stabilizes, the opening of the 1# cold shock valve is maintained at 95%, all 1# electric furnaces are opened, and the discharge rate of the smelting furnace is gradually increased to 80t / h. Under this state, the surface temperature of the catalyst of the second conversion layer rises to above 430℃ within 1h. After the second conversion layer meets the catalytic reaction conditions, the temperature of the second layer rises steadily.

[0027] The temperature between the second catalyst layers of the conversion rises to 450°C. The smelting furnace can gradually increase the material feeding amount to full load production, gradually shut down the furnace, and use the conversion of SO2 to SO3 as heat release to achieve self-heating balance of the conversion system. The temperature of the third layer can reach the catalytic reaction conditions in about 0.6h.

[0028] The overall conversion temperature reaches the normal production range, and the first-level power wave inlet pressure returns to a slightly negative pressure for production. It takes about 3 hours from the start of unloading from the smelting furnace to the normal conversion of the overall temperature.

[0029] During the specific operation, it should be noted that: during the temperature rise period of the conversion system, the 1# cold shock valve should be opened to between 40% and 60% in a predictable manner to prevent the second layer temperature from dropping too low during the temperature rise period. While ensuring that the first layer surface catalyst is heated according to the temperature rise curve, the number of 1# electric furnace opening groups should be adjusted.

[0030] In the initial stage of resumption of production, the electric heating furnace at the entrance of the first conversion layer should be kept in full operation and kept open. By increasing the opening of the 1# cold shock valve until it is fully open, the temperature of the first conversion layer is adjusted to 390-410℃, and the heat generated by the electric heating furnace is indirectly transferred to the second conversion layer.

[0031] The SO2 blower speed is increased as much as possible on the original basis to adjust the SO2 blower speed so that the negative pressure at the inlet of the purification first-level power wave is no more than 1KPa. At the same time, the smelting production load increase rate is increased to quickly transfer the reaction heat of the first layer to the second layer;

[0032] To ensure that the overall temperature of the conversion is controllable, pay attention to the flue gas temperature at the outlet of the electric heating furnace and ensure that it does not exceed 550°C, so as to effectively control the normal operation of the conversion equipment.

[0033] The present invention can achieve the purpose of avoiding the agglomeration of the surface layer of the second-layer catalyst, and reduce the low-temperature period of the second-layer catalyst from 6 hours to within 3 hours, effectively preventing SO3 from condensing into acid mist under low-temperature conditions, blocking the micropores of the catalyst, and even agglomerating on the surface of the catalyst, obstructing the normal circulation of flue gas, and significantly increasing the pressure difference of the catalyst layer, affecting the normal production load, and in severe cases causing the system to be paralyzed and unable to produce normally; effectively extending the service life of the catalyst, reducing production input, and at the same time providing guarantee for the long-term stable operation of the enterprise, effectively improving the profitability of the enterprise

[0034] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention; the dimensions of the drawings are not related to the specific objects, and the dimensions of the objects can be changed arbitrarily.

Claims

1. A process for preventing catalyst surface agglomeration, characterized by: The process for preventing catalyst surface agglomeration specifically comprises the following steps: Step 1) Heat up the conversion process. Start the SO2 blower to assist in heating. Maintain a slight negative pressure at the first-stage power wave inlet. Start the electric furnace and control the heating rate according to the heating curve. The heating rate is controlled within 30°C / h. Maintain the opening of the 1# cold shock valve at 40-60%. Step 2) Blanking production. The prerequisite for blanking production is that the surface temperature of the first and fourth layers of the conversion catalyst reaches 390-410°C. The initial blanking rate is controlled at 30t / h, the SO2 blower speed is increased, the inlet pressure of the first-stage power wave is maintained between -0.1 and -0.5kPa, the opening of the 1# cold shock valve is adjusted to 60-95%, and the number of electric furnace groups is increased to maintain the surface temperature of the first layer of the conversion catalyst between 390-410°C. Step 3) After the temperature between the catalyst layers continues to rise after the conversion, as the interlayer temperature continues to rise, the smelting furnace discharge rate is gradually increased, and the fan speed is increased at the same time. When the interlayer temperature rises to 460℃, the smelting furnace discharge rate is increased to 40t / h. When the interlayer temperature rises to 510℃, the smelting furnace discharge rate is increased to 50t / h. When the interlayer temperature rises to 550℃, the smelting furnace discharge rate is increased to 60t / h. During this period, the SO2 fan speed is gradually increased to 22HZ. Step 4) When the temperature between the catalyst layers of the first conversion layer rises to above 580°C, the fan speed is quickly increased to above 38 Hz, the reflux valve is opened to prevent a sudden increase in flow, and the reflux valve opening is adjusted to control the first-stage power wave inlet pressure to a negative pressure state, with the first-stage power wave inlet pressure being between -0.5 and -1.0 KPa. The opening of the 1# cold shock valve is maintained at 95%, all 1# electric furnaces are opened, and the smelting furnace discharge rate is gradually increased to 80t / h. Under this state, the surface temperature of the catalyst of the second conversion layer rises to above 430°C within 1 hour. After the second conversion layer meets the catalytic reaction conditions, the temperature of the second layer rises steadily; Step 5) When the temperature between the two catalyst layers rises to 450°C, the smelting furnace can gradually increase the material feeding rate to full capacity and gradually shut down the furnace; Step 6) The overall temperature is converted to the normal production range, and the first-stage power wave inlet pressure is restored to a slightly negative pressure for production.

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