Heat preservation and pressure reduction method for coke dry quenching overhaul and application

Abstract

The invention discloses a dry quenching maintenance heat preservation and pressure reduction method and application, firstly, in order to ensure that the brick temperature of a chute bracket part is above 650 DEG C in the heat preservation process of a dry quenching furnace, staged coke charging can be adopted to increase heat in the dry quenching furnace, so that the brick temperature of the chute bracket part is ensured, and secondly, the heat preservation and pressure reduction method aims at ensuring the temperature of the dry quenching furnace and the temperature of the chute bracket part in the heat preservation process of the dry quenching furnace. And thirdly, when the dry quenching furnace is subjected to heat preservation, low-temperature operation is carried out for a long time, and combustible components of circulating gas exceed the standard, the pressure of a pre-storage chamber of the dry quenching furnace can be adjusted to be micro-positive pressure for diffusion, so that the combustible components are reduced, and the energy consumption is reduced. The heat preservation and pressure reduction method for coke dry quenching maintenance is implemented successfully, and the expected plan effect is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dry quenching overhaul, in particular to a dry quenching overhaul heat preservation and pressure reduction method and application. BACKGROUND

[0002] The principle of dry quenching is to use inert gas to exchange heat with red coke in the dry quenching furnace to cool the coke, and the inert gas after absorbing the sensible heat of the red coke transmits heat to the waste heat boiler to generate steam for the steam turbine to generate power. The cooled inert gas is de-dusted and then introduced into the dry quenching furnace by the circulating fan for recycling.

[0003] The dry quenching system mainly consists of a coke conveying and cooling system, an inert gas circulating system, a steam-water system, and a dust removal system.

[0004] Due to the particularity of the dry quenching device, the domestic and world large-scale dry quenching devices should be overhauled annually according to the convention, and the annual overhaul of more than one month needs to be carried out every year. In view of this special situation, careful analysis shows that the main reason for the dry quenching device to be shut down for annual overhaul is not only the damage of the dry quenching furnace inclined way bracket brick, but also the damage of the local key equipment such as the water cooling jacket of the primary dust collector. SUMMARY

[0005] In order to make up for the deficiencies of the prior art, the present application provides a dry quenching overhaul heat preservation and pressure reduction method and application.

[0006] The purpose of the present application is to provide a dry quenching overhaul heat preservation and pressure reduction method, which comprises the following steps:

[0007] Step 1, gradually reduce the system load and gradually reduce the circulating air volume in the first stage, reduce the fan speed, correspondingly reduce the coke discharging amount, and keep the boiler inlet temperature within a stable range. This process should be carried out slowly to avoid thermal shock to the boiler and refractory materials;

[0008] Gradually close the pre-storage section pressure regulating valve to maintain a small opening to maintain a very small communication between the system and the atmosphere;

[0009] Step 2, isolate the gas circulation system in the second stage. When the circulating air volume and the coke discharging amount are reduced to the minimum, stop the coke discharging device, confirm that the coke on the coke discharging belt has been discharged, and before stopping the fan, the boiler inlet temperature is lower than 400℃. After gradually reducing the fan speed to the minimum, stop the circulating fan and close the sealing gas valves before and after the fan;

[0010] Close the circulating fan outlet, close the N2 valve and air valve for introducing air (quenching), and ensure that the system is completely isolated from the air;

[0011] Step 3, the third stage nitrogen purging and insulation, by injecting inert gas (nitrogen) to replace the combustible gas in the system, and maintain the positive pressure, to prevent air suction;

[0012] Step 4, the fourth stage natural cooling and pressure reduction, control the cooling rate, the slow cooling of the dry quenching furnace, to prevent the refractory cracking due to rapid cooling;

[0013] By opening the pre-storage section of the relief valve (PV valve or bypass valve) intermittently and small opening, to achieve pressure reduction and slow cooling;

[0014] Step 5, the fifth stage of the final gas replacement, after the system is cooled to room temperature and the pressure is normal, at the planned opening of the manhole, using portable gas detector for detection.

[0015] Further, the boiler inlet temperature control uses water jacket operation to reduce the boiler inlet temperature. During normal operation of the boiler, high-temperature boiler water is continuously or intermittently discharged from the bottom of the boiler drum (steam drum), while continuously supplementing the boiler with lower-temperature desalted water or deoxygenated water.

[0016] Further, in step 3, the stage loading of coke is used to increase the heat in the dry quenching furnace to ensure the brick temperature of the inclined leg.

[0017] Further, in step 3, nitrogen purging is started, the system nitrogen filling valve is opened, and nitrogen is continuously filled into the system. Multiple injection points are set in the circulating gas channel and the primary dust collector.

[0018] After confirming the qualified gas composition, adjust the nitrogen injection amount, the dry quenching furnace is in the state of smothering, relying on the heat accumulated by the refractory material for insulation, and the nitrogen is responsible for pressure maintenance and inert environment maintenance.

[0019] Further, in step 3, the pressure of the dry quenching furnace pre-storage chamber is adjusted to a slight positive pressure for relief, so that the system pressure is stabilized at a slight positive pressure state, reducing the combustible components.

[0020] Further, in step 4, the cooling rate is required to be <50℃ / h, which is determined according to the requirements of the refractory material.

[0021] Further, in step 4, nitrogen is supplemented. During the relief and pressure reduction process, the system pressure will drop. According to the pressure situation, nitrogen is intermittently supplemented to maintain the system at a slight positive pressure to prevent air suction;

[0022] During the relief and pressure reduction process, the gas composition is monitored to ensure that the O2 content is always within a safe range until the temperature in the dry quenching furnace drops to about ambient temperature +40℃ or the required temperature for maintenance.

[0023] The application of the dry quenching maintenance heat preservation pressure reduction method to the dry quenching device hot maintenance heat preservation pressure reduction saves the maintenance time, prolongs the effective operation time of the dry quenching device, and improves the dry quenching yield.

[0024] Compared with the prior art, the beneficial effects of the present application are:

[0025] The dry quenching device hot maintenance heat preservation pressure reduction method used during maintenance not only scientifically saves the maintenance time, prolongs the effective operation time of the dry quenching device, but also greatly improves the dry quenching yield, and is only for the coking dry quenching diffusion field.

[0026] The present application successfully achieves the target of heat preservation above 650 DEG C by analyzing the measurement and control parameters of the dry quenching furnace, the boiler system is reduced to the normal pressure state, and the maintenance operation is successfully completed, and the ideal effect is achieved. Through one year of production operation, the method is safe and reliable, not only scientifically saves the maintenance time, prolongs the effective operation time of the dry quenching device, but also greatly improves the dry quenching yield, and provides a train of thought for the hot maintenance of the dry quenching system equipment, and lays a valuable practical experience. DETAILED DESCRIPTION

[0027] In order for those skilled in the art to better understand the technical solutions in the embodiments of the present application, and to make the above-mentioned purposes, features and advantages of the present application more apparent and easy to understand, the specific embodiments of the present application are further described below.

[0028] The endpoints of the ranges and any values disclosed in this document are not limited to the precise values stated. These ranges and values should be construed as having endpoints that are near the value that is stated. For ranges, the endpoints are determined with by adding or subtracting 1% from the upper and lower threshold of the given range. For others, the endpoints are determined to be the nearest tenth. The disclosure of values also pertains to approximations of the values. For numerical values of a range, the endpoints between the values of each range, the endpoints between the values of each range and individual point values, and individual point values can be combined to create one or more new ranges of values that are within the scope of the disclosure. Specific embodiment one:

[0030] A dry quenching maintenance heat preservation pressure reduction method, comprising the following steps:

[0031] Step 1, gradually reduce the system load, according to the plan, gradually reduce the circulating air volume, reduce the exhaust amount by reducing the fan speed, and keep the boiler inlet temperature in a stable range, this process should be slow to avoid thermal shock to the boiler and refractory material;

[0032] Gradually close the pre-storage section pressure regulating valve, keep a small opening to maintain a very small communication between the system and the atmosphere;

[0033] Step 2, the second stage gas circulation system isolation, when the circulating air volume and the amount of coke is reduced to a minimum, stop the coke discharge device, confirm that the coke on the coke discharge belt has been emptied, before stopping the fan, the boiler inlet temperature is lower than 400℃, the fan speed is gradually reduced to a minimum, then stop the circulating fan, close the sealing gas valve before and after the fan;

[0034] Close the circulating fan outlet, close the N2 valve and air valve for introducing air (quenching), ensure that the system is completely isolated from the air;

[0035] Step 3, the third stage nitrogen blowing and heat preservation and pressure maintenance, replace the combustible gas in the system by injecting inert gas (nitrogen), and maintain positive pressure to prevent air from being sucked in;

[0036] Step 4, the fourth stage natural cooling and pressure reduction, control the cooling rate, the dry quenching furnace is slowly cooled to prevent the refractory from cracking due to rapid cooling;

[0037] The pressure reduction and slow cooling are achieved by intermittently and small opening degree opening the pre-storage section pressure relief valve (PV valve or bypass valve);

[0038] Step 5, the fifth stage final gas replacement, after the system is cooled to room temperature and the pressure is normal, use a portable gas detector to detect at the planned opening manhole.

[0039] The boiler inlet temperature control uses water jacketing operation to reduce the boiler inlet temperature, during normal operation of the boiler, continuously or intermittently discharge high temperature boiler water from the bottom of the boiler drum (steam drum), while continuously supplementing lower temperature desalted water or deaerated water into the boiler.

[0040] The step 3 uses phased charging to increase the heat in the dry quenching furnace to ensure the brick temperature of the inclined way bracket.

[0041] The step 3 starts nitrogen blowing, opens the system nitrogen filling valve, continuously fills nitrogen into the system, sets multiple injection points, and the multiple injection points are arranged on the circulating gas channel and the primary dust collector;

[0042] After confirming that the gas composition is qualified, adjust the nitrogen injection amount, the dry quenching furnace is in the state of smothering, relies on the heat accumulated by the refractory to keep warm, and the nitrogen is responsible for pressure maintenance and inert environment maintenance.

[0043] The step 3 adjusts the pressure of the dry quenching furnace pre-storage chamber to a slight positive pressure for diffusion, so that the system pressure is stabilized at a slight positive pressure state, and the combustible components are reduced.

[0044] The step 4 requires a cooling rate <50℃ / h, which is determined according to the requirements of the refractory material.

[0045] The step 4 is supplemented with nitrogen, and during the pressure reduction by diffusion, the system pressure will decrease, and according to the pressure condition, nitrogen is supplemented intermittently, so as to always maintain the system in a slight positive pressure state and prevent air from being sucked back;

[0046] During the pressure reduction by diffusion, the gas composition is monitored to ensure that the O2 content is always within a safe range until the temperature in the dry quenching furnace is reduced to about ambient temperature + 40℃ or the required temperature for maintenance.

[0047] In the above embodiment, during the pressure reduction by insulation, firstly, in order to ensure that the brick temperature at the inclined way bracket part is above 650℃ during the dry quenching furnace insulation process, phased coke charging can be used to increase the heat in the dry quenching furnace, so as to ensure the brick temperature at the inclined way bracket part, secondly, for the dry quenching furnace insulation process, both the dry quenching furnace temperature and the boiler inlet temperature need to be reduced, so when necessary, water jacketing operation is used to reduce the boiler inlet temperature, thirdly, during the dry quenching furnace insulation, long-term low-temperature operation leads to excessive combustible components in the circulating gas, so the dry quenching furnace pre-storage chamber pressure can be adjusted to a slight positive pressure for diffusion, so as to reduce the combustible components, so that the dry quenching maintenance insulation pressure reduction method is successfully implemented, and the expected plan effect is achieved. Specific embodiment two:

[0049] The application of a dry quenching maintenance insulation pressure reduction method to the dry quenching device hot-state maintenance insulation pressure reduction saves maintenance time, prolongs the effective operation time of the dry quenching device, and improves the dry quenching yield.

[0050] It is apparent to those skilled in the art that the present application is not limited to the details of the foregoing exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, and the scope of the present application is defined by the appended claims rather than the foregoing description, and it is intended to encompass all changes falling within the meaning and range of equivalents of the elements of the claims.

[0051] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be properly combined to form other embodiments that those skilled in the art can understand.

Claims

1. A method for dry quenching coke maintenance, characterized in that, Includes the following steps: Step 1: In the first stage, gradually reduce the system load and the circulating air volume. By reducing the fan speed, the amount of coke discharged is reduced accordingly, and the boiler inlet temperature is kept within a stable range. Gradually close the pre-stored pressure regulating valve, maintaining a very small opening to ensure a minimal connection between the system and the atmosphere; Step 2, the second stage of gas circulation system isolation. After the circulating air volume and coke discharge volume are reduced to the minimum, the coke discharge device is stopped. It is confirmed that the coke on the coke discharge belt has been discharged. Before stopping the blower, the boiler inlet temperature is below 400℃. After gradually reducing the blower speed to the minimum, the circulating blower is stopped and the sealing gas valves before and after the blower are closed. Close the outlet of the circulating fan, and close the N2 valve and air valve used for introducing air (coke quenching) to ensure that the system is completely isolated from the air; Step 3, the third stage of nitrogen purging and heat preservation and pressure maintenance, involves injecting inert gas (nitrogen) to replace the combustible gas in the system and maintaining positive pressure to prevent air from being drawn in; Step 4; The fourth stage involves natural cooling and depressurization, controlling the cooling rate. The cooling of the dry quenching furnace is carried out slowly to prevent the refractory material from cracking and being damaged due to rapid cooling. Pressure reduction and slow cooling are achieved by intermittently and slightly opening the pre-stored section vent valve; Step 5; The fifth stage is the final gas replacement. After the system has cooled to room temperature and the pressure is at atmospheric pressure, a portable gas detector is used to detect the gas at the planned manhole.

2. The method for dry quenching coke maintenance, heat preservation, and pressure reduction according to claim 1, characterized in that: The boiler inlet temperature control is achieved by performing a water jacketing operation to reduce the boiler inlet temperature. During normal boiler operation, high-temperature boiler water is continuously or intermittently discharged from the bottom of the boiler drum (boiler drum), while low-temperature demineralized water or deoxygenated water is continuously added to the boiler.

3. The method for dry quenching coke maintenance, heat preservation, and pressure reduction according to claim 2, characterized in that: In step 3, staged coking is used to increase the heat inside the dry quenching furnace and ensure the brick temperature at the inclined cofferdam section.

4. The method for dry quenching coke maintenance, heat preservation, and pressure reduction according to claim 3, characterized in that: In step 3, nitrogen purging is initiated by opening the system nitrogen charging valve and continuously charging nitrogen into the system. Multiple injection points are set up in the circulating gas channel and the primary dust collector. After confirming that the gas composition is qualified, the nitrogen injection rate is adjusted, and the dry quenching furnace is in a closed state, relying on the heat stored in the refractory material for heat preservation, while nitrogen is responsible for maintaining pressure and maintaining an inert environment.

5. The method for dry quenching coke maintenance, heat preservation, and pressure reduction according to claim 4, characterized in that: Step 3 involves adjusting the pressure in the pre-storage chamber of the dry quenching furnace to a slightly positive pressure for venting, thereby stabilizing the system pressure at a slightly positive pressure state and reducing the combustible components.

6. The method for dry quenching coke maintenance, heat preservation, and pressure reduction according to claim 5, characterized in that: Step 4 requires a cooling rate of <50℃ / h, which depends on the requirements of the refractory material.

7. The method for dry quenching coke maintenance, heat preservation, and pressure reduction according to claim 6, characterized in that: In step 4, nitrogen is added. During the release and depressurization process, the system pressure will drop. Nitrogen is added intermittently according to the pressure situation to always maintain a slight positive pressure in the system and prevent air backflow. During the venting and depressurization process, monitor the gas composition to ensure that the O2 content remains within a safe range until the temperature inside the dry quenching furnace drops to approximately ambient temperature +40°C or the temperature required for maintenance.

8. An application of the dry quenching maintenance heat preservation and pressure reduction method according to claim 7, wherein the dry quenching maintenance heat preservation and pressure reduction method according to claim 7 is applied to the hot maintenance heat preservation and pressure reduction of the dry quenching unit, thereby saving maintenance time, extending the effective operating time of the dry quenching unit, and increasing the dry quenching output.