Hot preparation method for high-solid-content oil slurry heating furnace of direct coal liquefaction device

Abstract

The invention discloses a hot standby method for a high-solid-content oil slurry heating furnace of a direct coal liquefaction device. The hot standby method comprises the following steps: cutting off communication between an inlet end of a standby furnace tube and a heating furnace inlet header pipe and communication between an outlet end of the standby furnace tube and a heating furnace outlet header pipe; the inlet end of the standby furnace tube is communicated with the flushing oil supply pipe, and the outlet end of the standby furnace tube is communicated with the flushing oil return pipe, so that the flushing oil fills the standby furnace tube and then returns to the flushing oil return pipe; igniting a burner nozzle of a radiation chamber of the standby hearth, and controlling the temperature of the standby hearth to a preset temperature by adjusting the flow of gas serving as fuel; and after the temperature of the standby hearth reaches the preset temperature, the oil feeding flow of flushing oil conveyed to the standby furnace tube and / or the oil returning flow of flushing oil entering the flushing oil returning tube are / is adjusted, so that the pressure of the standby furnace tube is controlled to reach the preset pressure. The heating furnace can be switched at the first time when having a fault, and stable operation is ensured.

Description

Technical Field

[0001] The present invention belongs to the field of direct coal liquefaction, and specifically is a hot standby method for a high-solid oil slurry heating furnace in a direct coal liquefaction device. It can also be applied to the hot standby of solid-containing heating furnaces and high-viscosity heating furnaces in the fields of petrochemicals, basic chemicals, etc. Background Art

[0002] The fractionation system of the suspended bed coal direct liquefaction device has three parts: an atmospheric tower, a heating furnace and a vacuum tower. Its main function is to separate the liquefied oil generated by the reaction through atmospheric and vacuum distillation. The separated heavy liquefied oil is sent to the hydrogenation stabilization device for re-hydrogenation. The coal liquefied asphalt with a solid content of about 50% is discharged from the bottom of the vacuum tower and sent to the asphalt molding unit for cooling and molding. The heating furnace is set on the inlet pipeline of the vacuum tower. Its function is to heat the oil slurry at the bottom of the atmospheric tower from 370℃ to 410℃, increase the feed temperature of the vacuum tower, and thus increase the oil extraction rate of the vacuum tower.

[0003] The heating furnace of the coal direct liquefaction fractionation system is a pure radiation chamber double-sided radiation heating furnace. The heating medium is atmospheric tower bottom oil slurry, ash content: 6%, solid content: 20%, n-hexane insoluble matter: 41%, with the characteristics of high ash, high solid and high viscosity. At the same time, the heating medium contains certain light components, which are easy to gasify in the furnace tube to form a three-phase flow state, which has a strong erosion effect on the furnace tube and is easy to cause coking of the furnace tube. In order to prevent erosion of the furnace tube, the furnace adopts large-radius elbows arranged horizontally. At the same time, the coking of the furnace tube is delayed by increasing the furnace tube flow, reducing the light components of the furnace tube, and controlling the furnace temperature.

[0004] In the previous optimization and transformation, the atmospheric tower was expanded and transformed, and the operating pressure of the atmospheric tower was reduced, which greatly increased the oil extraction rate of the atmospheric tower, resulting in a reduction in the bottom material, which in turn led to a reduction in the feed of the heating furnace and a significant reduction in the flow rate of the medium in the furnace tube. As we all know, ensuring a certain flow rate in the tube is the key to delaying the coking of the furnace tube. Therefore, in order to increase the flow rate of the heating furnace pipeline, it is possible to consider reducing the number of furnace tubes in operation. For example, the double furnace of the heating furnace was optimized and transformed, and the furnace tube and flue of the heating furnace were separated and transformed to achieve an operation mode of one operation and one standby in the two furnaces.

[0005] The single furnace transformation of the coal direct liquefaction fractionation heating furnace effectively delays the coking of the furnace tubes. However, as the operation time of the heating furnace increases, coking will inevitably occur in the furnace tubes. There are two types of coking materials: one is the coking on the upper part of the tube wall after the light component is gasified, and the other is the coking of the heavy component attached to the lower part of the tube wall. When the system fluctuates, the parameters such as the temperature, pressure and flow of the furnace tube change, causing the coking materials to fall off and block the downstream pipeline, or get stuck in the valve core of the pressure reducing valve at the inlet of the pressure reducing tower, causing the system to fluctuate greatly, and the system is forced to reduce the load, etc., which may cause the device to be forced to shut down. Therefore, the stable operation of the heating furnace is particularly important. This requires the spare furnace to be kept in a hot standby state at all times, so that it can be switched in time when the operating furnace fails, and the harm of system fluctuations can be minimized. Summary of the invention

[0006] The purpose of the present invention is to provide a hot standby method for a high-solid oil slurry heating furnace of a coal direct liquefaction device to ensure that the heating furnace can be switched immediately when a failure occurs, thereby ensuring the stable operation of the coal direct liquefaction device.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A hot standby method for a high-solid content oil slurry heating furnace of a coal direct liquefaction device, wherein the heating furnace has two independently operated furnaces, and when the heating furnace operates normally, one of the two furnaces is used as an operating furnace to heat the oil slurry, and the other is used as a standby furnace;

[0009] The standby furnace is equipped with corresponding standby furnace tubes, and the operating furnace is equipped with corresponding operating furnace tubes, so as to be used for heating the oil slurry during normal operation;

[0010] The inlet end of the standby furnace tube is connected to the flushing oil supply pipe and the heating furnace inlet main pipe through the first branch pipe and the second branch pipe respectively, and the inlet end of the operating furnace tube is connected to the flushing oil supply pipe and the heating furnace inlet main pipe through the third branch pipe and the fourth branch pipe respectively;

[0011] The outlet end of the standby furnace tube is connected to the flushing oil return pipe and the heating furnace outlet main pipe through the fifth branch pipe and the sixth branch pipe respectively, and the outlet end of the operating furnace tube is connected to the flushing oil return pipe and the heating furnace outlet main pipe through the seventh branch pipe and the eighth branch pipe respectively;

[0012] The hot standby method comprises the following steps:

[0013] S1) operating a valve to cut off the connection between the inlet end of the spare furnace tube and the inlet main pipe of the heating furnace and the connection between the outlet end of the spare furnace tube and the outlet main pipe of the heating furnace;

[0014] S2) operating the valve to connect the inlet end of the standby furnace tube with the flushing oil supply pipe and the outlet end of the standby furnace tube with the flushing oil return pipe, so that the flushing oil fills the standby furnace tube and then returns to the flushing oil return pipe to prevent the standby furnace tube from overpressure;

[0015] S3) igniting the burner of the radiation chamber of the standby furnace, and controlling the temperature of the standby furnace to a preset temperature by adjusting the flow rate of the gas used as fuel;

[0016] S4) After the temperature of the standby furnace reaches the preset temperature, the supply flow rate of the flushing oil delivered to the standby furnace tube and / or the return flow rate of the flushing oil entering the flushing oil return pipe are adjusted to control the pressure of the standby furnace tube to the preset pressure, so as to achieve the purpose of constant temperature and constant pressure standby.

[0017] According to the hot standby method of the present invention, preferably, the hot standby method also includes step S5) when the operating furnace fails or stops working due to routine switching, firstly, the flushing oil return from the spare furnace pipe is switched from the flushing oil return pipe to the heating furnace outlet main pipe, and the flushing oil flow entering the spare furnace pipe is increased, the burners of the spare furnace are increased, and then the standby furnace is heated to the required switching temperature as required before the switching operation is performed.

[0018] According to the hot standby method of the present invention, preferably, a spare furnace tube flushing oil supply manual valve is provided on the first branch pipe, a spare furnace tube inlet regulating valve front manual valve is provided on the second branch pipe, and a spare furnace tube inlet regulating valve and a spare furnace tube inlet regulating valve rear manual valve are also provided in sequence at the inlet end of the spare furnace tube along the logistics direction.

[0019] According to the hot standby method of the present invention, preferably, the third branch pipe is provided with an operating furnace tube flushing oil supply manual valve, the fourth branch pipe is provided with an operating furnace tube inlet regulating valve front manual valve, and the inlet end of the operating furnace tube is also provided with an operating furnace tube inlet regulating valve and an operating furnace tube inlet regulating valve rear manual valve in sequence along the logistics direction.

[0020] According to the hot standby method of the present invention, preferably, a spare furnace tube flushing oil return manual valve is provided on the fifth branch pipe, and a spare furnace tube outlet manual valve is provided on the sixth branch pipe.

[0021] According to the hot standby method of the present invention, preferably, the seventh branch pipe is provided with an operating furnace tube flushing oil return manual valve, and the eighth branch pipe is provided with an operating furnace tube outlet manual valve.

[0022] In a preferred embodiment, the oil slurry has an ash content of 4%-8%, such as 6%, a solid content of 18%-22%, such as 20%, and a n-hexane insoluble matter content of 37%-45%, such as 41%, all of which are mass contents.

[0023] According to the hot standby method of the present invention, preferably, the preset temperature in step S3 is 230±5° C., and the preset pressure in step S4 is 0.9±0.1 MPa.

[0024] In a preferred embodiment, the heating furnace is modified from an original heating furnace, wherein the two furnaces of the original heating furnace share a convection chamber and a flue, and during the modification, two partition walls are added to the convection chamber of the original heating furnace to completely separate the convection chamber of the original heating furnace from the middle position to form two independent convection chambers; at the same time, the flue gases of the radiation chambers of the two furnaces enter their respective convection chambers, and a gate valve is provided in the flue of each furnace, so that the combustion conditions of the two furnaces can be controlled separately by controlling the gate valve on the flue, thereby achieving the goal that the two furnaces can operate separately without interfering with each other.

[0025] In a preferred embodiment, in order to facilitate the decoking of the removed furnace chamber, during the modification, the bent pipe portion of the furnace tube in the furnace chamber of the original heating furnace is moved from inside the furnace chamber to outside the furnace chamber, and is connected using a flange connection that is easy to disassemble, so that the bent pipe portion can be removed to decoke the furnace tube in sections.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] In order to achieve the hot standby condition of the standby heating furnace, the prior art usually completely removes the solid-containing medium of the standby heating furnace and then fills the standby furnace tube with flushing oil. However, the actual operation is not ideal. In the early stage of hot standby, the flushing oil of the standby furnace tube is full of pipes. As the furnace temperature increases, the flushing oil in the furnace tube undergoes thermal expansion, causing the furnace tube pressure to increase rapidly. The furnace tube has to be depressurized, resulting in the flushing oil in the furnace tube being discharged, causing the furnace tube to be unable to be fully hot-standby, seriously affecting the safe operation of the furnace tube. The overpressure of the furnace tube will be caused if you are not careful. Moreover, after multiple pressure reliefs, a large amount of oil products in the furnace tube are discharged, and the furnace tube is half-filled with oil. The light components in the flushing oil in the tube undergo phase transition between liquid and gas as the temperature changes. Moreover, due to the small position of the gas control valve, it is difficult to find a suitable balance point, which is difficult to operate and is extremely unfavorable for safe production.

[0028] The present invention achieves the purpose of keeping the standby furnace at a constant temperature and pressure. By modifying the convection chamber, the furnace tube decoking elbow and the continuous flushing oil process, the operating conditions of the two furnaces can be non-interfering with each other, and the medium in the standby furnace tube maintains a continuous flow state, which solves the problem of independent temperature control of the standby furnace and phase change of the medium inside the furnace tube caused by temperature accumulation due to non-flow of the furnace tube, thereby rapidly increasing the pressure and causing overpressure of the furnace tube. At the same time, it solves the problem that the furnace temperature cannot meet the standby requirements due to overpressure of the furnace tube.

[0029] After the invention is completed, the furnace tube pressure, furnace temperature and gas consumption all reach a stable operating state, which greatly reduces the operating difficulty, reduces the labor intensity of operators, and improves the happiness index of operators.

[0030] The present invention has made a lot of improvements and innovations in design, production, and commissioning, and has proposed a series of control indicators to avoid overpressure damage to the furnace tube during the hot standby process of the heating furnace, thereby improving the safety of the hot standby of the solid-containing heating furnace. It shortens the switching time of the standby furnace, prolongs the operation cycle of the device, and increases the benefits for the company. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The invention relates to a high-solid-content oil slurry heating furnace system of a coal direct liquefaction device used in the hot standby method of the present invention.

[0032] Description of reference numerals:

[0033] 101, heating furnace; 201, front hand valve of spare furnace tube inlet regulating valve; 202, rear hand valve of spare furnace tube inlet regulating valve; 203, spare furnace tube outlet hand valve; 204, spare furnace tube flushing oil supply hand valve; 205, spare furnace tube flushing oil return hand valve; 206, front hand valve of operating furnace tube inlet regulating valve; 207, rear hand valve of operating furnace tube inlet regulating valve; 208, operating furnace tube outlet hand valve; 209, operating furnace tube flushing oil supply hand valve; 210, operating furnace tube flushing oil return hand valve; 301, spare furnace tube inlet regulating valve; 302 operating furnace tube inlet regulating valve;

[0034] 1. Heating furnace inlet main pipe; 2. Heating furnace outlet main pipe; 3. Flushing oil supply pipe; 4. Flushing oil return pipe; 11. First branch pipe; 12. Second branch pipe; 13. Third branch pipe; 14. Fourth branch pipe; 15. Fifth branch pipe; 16. Sixth branch pipe; 17. Seventh branch pipe; 18. Eighth branch pipe. DETAILED DESCRIPTION

[0035] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0036] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0037] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so as to describe the embodiments of the present invention described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0038] In order to ensure the safe and effective standby of the heating furnace, the hot standby process of the heating furnace is modified to achieve the purpose of safe standby of the heating furnace at constant temperature and pressure, so as to ensure that the heating furnace can be switched at the first time when a fault occurs, and to ensure the stable operation of the coal direct liquefaction device. The present invention provides a hot standby method for a high-solid oil slurry heating furnace in a coal direct liquefaction device, wherein the ash content of the high-solid oil slurry can be 4%-8%, such as 6%, the solid content can be 18%-22%, such as 20%, and the n-hexane insoluble matter content can be 37%-45%, such as 41%, and the above are all mass contents.

[0039] Among them, Figure 1 As shown, the heating furnace 101 has two independently operated furnaces, and when the heating furnace operates normally, one of the two furnaces is used as an operating furnace to heat the oil slurry, and the other is used as a standby furnace so that it can be switched to the operating furnace when needed (such as when the current operating furnace is under maintenance).

[0040] The heating furnace is well known in the art, and its configuration includes a furnace, a radiation chamber, a furnace tube, a convection chamber, a burner or a burner, and a flue or a flue gas channel, which are conventional configurations of a heating furnace and will not be described in detail here.

[0041] Among them, it is known in the art that the spare furnace is equipped with corresponding spare furnace tubes and the operating furnace is equipped with corresponding operating furnace tubes, so as to be used for heating the oil slurry during normal operation; for example, these furnace tubes include curved tube parts and straight tube parts, so as to be spirally wound upward or downward in their respective furnaces, and the two ends of the spirally wound furnace tubes in the horizontal direction are curved tube parts.

[0042] The inlet end of the spare furnace tube is connected to the flushing oil supply pipe 3 and the heating furnace inlet main pipe 1 through the first branch pipe 11 and the second branch pipe 12 respectively, and the inlet end of the operating furnace tube is connected to the flushing oil supply pipe 3 and the heating furnace inlet main pipe 4 through the third branch pipe 13 and the fourth branch pipe 14 respectively.

[0043] In some embodiments, a spare furnace tube flushing oil supply manual valve 204 is provided on the first branch pipe 11, a spare furnace tube inlet regulating valve front manual valve 201 is provided on the second branch pipe 12, and a spare furnace tube inlet regulating valve 301 and a spare furnace tube inlet regulating valve rear manual valve 202 are provided in sequence at the inlet end of the spare furnace tube along the logistics direction, and these valves are provided to facilitate regulation and operation.

[0044] In some embodiments, the third branch pipe 13 is provided with a manual valve 209 for supplying flushing oil to the operating furnace tube, the fourth branch pipe 14 is provided with a manual valve 206 before the operating furnace tube inlet regulating valve, and the inlet end of the operating furnace tube is also provided with an operating furnace tube inlet regulating valve 302 and a manual valve 207 after the operating furnace tube inlet regulating valve in sequence along the logistics direction, and these valves are set to facilitate regulation and control of operations.

[0045] The outlet end of the standby furnace tube is connected to the flushing oil return pipe 4 and the heating furnace outlet main pipe 2 through the fifth branch pipe 15 and the sixth branch pipe 16 respectively; the outlet end of the operating furnace tube is connected to the flushing oil return pipe 4 and the heating furnace outlet main pipe 2 through the seventh branch pipe 17 and the eighth branch pipe 18 respectively.

[0046] In some embodiments, a spare furnace pipe flushing oil return manual valve 205 is provided on the fifth branch pipe 15, and a spare furnace pipe outlet manual valve 203 is provided on the sixth branch pipe 16. These valves are provided to facilitate regulation and control of operation.

[0047] In some embodiments, the seventh branch pipe 17 is provided with a manual valve 210 for returning the flushing oil of the running furnace pipe, and the eighth branch pipe 18 is provided with a manual valve 208 for an outlet of the running furnace pipe, and these valves are provided to facilitate regulation of operation.

[0048] The hot standby method of the present invention comprises the following steps:

[0049] S1) operating a valve to cut off the connection between the inlet end of the spare furnace tube and the inlet main pipe of the heating furnace and the connection between the outlet end of the spare furnace tube and the outlet main pipe of the heating furnace;

[0050] Specifically, the front hand valve 201 of the spare furnace tube inlet and the rear hand valve 202 of the spare furnace tube inlet regulating valve of the spare furnace chamber can be closed to ensure that the spare furnace tube is completely removed;

[0051] S2) operating the valve to connect the inlet end of the standby furnace tube with the flushing oil supply pipe and the outlet end of the standby furnace tube with the flushing oil return pipe, so that the flushing oil fills the standby furnace tube and then returns to the flushing oil return pipe to prevent the standby furnace tube from overpressure;

[0052] Specifically, the spare furnace pipe flushing oil supply manual valve 204 can be opened, the spare furnace pipe inlet regulating valve 301 can be opened, the spare furnace pipe inlet regulating valve rear manual valve 202 can be opened to fill the spare furnace pipe with flushing oil, and the spare furnace rear flushing oil return manual valve 205 can be opened to return the flushing oil to the flushing oil return main pipe;

[0053] S3) igniting the burner of the radiation chamber of the standby furnace, and controlling the temperature of the standby furnace to a preset temperature by adjusting the flow rate of the gas used as fuel; wherein the arrangement of the burner in the radiation chamber is well known in the art, and the burner provides heat by burning fuel such as gas;

[0054] Specifically, 2-3 burners can be ignited in the spare furnace radiation chamber, and the furnace tube temperature can be controlled at 230±5℃ by adjusting the gas flow rate;

[0055] S4) After the temperature of the standby furnace reaches the preset temperature, the supply flow rate of the flushing oil delivered to the standby furnace tube and / or the return flow rate of the flushing oil entering the flushing oil return pipe are adjusted to control the pressure of the standby furnace tube to the preset pressure, so as to achieve the purpose of constant temperature and constant pressure standby.

[0056] Specifically, after the standby furnace temperature reaches the preset temperature of 230±5°C, the standby furnace tube flushing oil supply manual valve 204 and the standby furnace tube flushing oil return manual valve 205 can be adjusted again to control the standby furnace tube pressure at 0.9±0.1MPa to achieve the purpose of constant temperature and pressure standby.

[0057] Preferably, the hot standby method also includes step S5) when the operating furnace fails or stops working due to routine switching, the flushing oil return from the spare furnace pipe is first switched from the flushing oil return pipe 4 to the heating furnace outlet main pipe 2, and the flushing oil flow entering the spare furnace pipe is increased, the burners of the spare furnace are increased, and then the standby furnace is heated to the required switching temperature as required before the switching operation is performed.

[0058] In a preferred embodiment, the heating furnace is modified from an original heating furnace, wherein the two furnaces of the original heating furnace share a convection chamber and a flue, and during the modification, two partition walls are added to the convection chamber of the original heating furnace to completely separate the convection chamber of the original heating furnace from the middle position to form two independent convection chambers; at the same time, the flue gases of the radiation chambers of the two furnaces enter their respective convection chambers, and a gate valve is provided in the flue of each furnace, so that the combustion conditions of the two furnaces can be controlled separately by controlling the gate valve on the flue, thereby achieving the goal that the two furnaces can operate separately without interfering with each other.

[0059] In a preferred embodiment, in order to facilitate the decoking of the removed furnace chamber, during the modification, the bent pipe portion of the furnace tube in the furnace chamber of the original heating furnace is moved from inside the furnace chamber to outside the furnace chamber, and is connected using a flange connection that is easy to disassemble, so that the bent pipe portion can be removed to decoke the furnace tube in sections.

[0060] In a preferred embodiment, during the transformation, in order to ensure that the spare furnace can be effectively isolated from the high-solid oil slurry, a sliding plate valve with better sealing performance is added to the inlet and outlet of the original heating furnace, and the inlet and outlet valves of the spare furnace are closed to ensure that the spare furnace can be effectively removed.

[0061] The following is further described in conjunction with the embodiments / comparative examples.

[0062] Example

[0063] 1) If Figure 1 As shown, a high-temperature and low-pressure flushing oil (HLP) supply process is added after the hand valve 201 before the spare furnace tube inlet regulating valve, and the flushing oil temperature is 300°C and the pressure is 2.0MPa. A high-temperature and low-pressure flushing oil return process is added before the hand valve 203 at the spare furnace tube outlet. The flushing oil is put into use to fill the spare furnace tube with the flushing oil, and the spare furnace tube flushing oil return hand valve 205 connected to the flushing oil return pipe 4 is opened to return the flushing oil to the flushing oil return pipe. The flow rate is controlled at 2t / h. The main purpose of the circulation is to prevent overpressure of the furnace tube;

[0064] 2) Adjust the negative pressure of the spare furnace to about -30KPa by adjusting the relevant valves of the spare furnace, such as the flue plug valve, ignite 2-3 burners in the radiation chamber of the spare furnace, and slowly increase the furnace temperature to 230±5℃ by adjusting the gas flow;

[0065] 3) After the temperature reaches the preset temperature, adjust the valves controlling the flushing oil in and out of the standby furnace tube again to control the pressure of the standby furnace tube at 0.9±0.1MPa, and minimize the amount of flushing oil while meeting the furnace tube pressure, ultimately achieving the purpose of constant temperature and pressure standby;

[0066] 4) When a fault occurs in the operating furnace or a routine switch is required, first close the valve connecting the spare furnace pipe to the flushing oil return pipe, open the valve from the spare furnace pipe to the heating furnace outlet main pipe, increase the inlet flushing oil flow rate and increase the number of spare furnace nozzles (that is, increase the number of nozzles ignited), and heat the spare furnace to the required switching temperature as required before performing the switching operation.

[0067] After running for a period of time, it is proved that the present invention has achieved the purpose of keeping the standby furnace at a constant temperature and pressure. By modifying the convection chamber, the furnace tube coke cleaning elbow and the continuous flushing oil process, the operating states of the two furnaces can be made non-interfering with each other, and the medium in the standby furnace tube maintains a continuous flow state, which solves the problem of independent temperature control of the standby furnace and phase change of the medium inside the furnace tube caused by temperature accumulation due to non-flow of the furnace tube, and then the pressure increases rapidly to cause overpressure of the furnace tube. At the same time, it solves the problem that the furnace temperature cannot meet the standby requirement due to overpressure of the furnace tube pressure.

[0068] Comparative Example

[0069] In the past, in order to achieve the hot standby condition of the standby heating furnace, the solid medium of the standby heating furnace was completely removed, and then the standby furnace tube was filled with flushing oil. 2-3 burners were ignited in the radiation chamber to try to control the pipeline at 200±5℃ and the pressure at 0.9±0.1MPa. However, the actual operation was not ideal. In the early stage of hot standby, the flushing oil of the standby furnace tube was full. As the furnace temperature increased, the flushing oil in the furnace tube expanded thermally, causing the furnace tube pressure to increase rapidly. The furnace tube had to be depressurized, resulting in the flushing oil in the furnace tube being discharged, causing the furnace tube to be unable to be fully hot-standby, seriously affecting the safe operation of the furnace tube. The slightest carelessness will cause overpressure in the furnace tube, and after multiple pressure reliefs, a large amount of oil in the furnace tube is discharged, and the furnace tube is half-filled with oil. The light components in the flushing oil in the tube undergo phase transitions from liquid to gas as the temperature changes. In addition, due to the small position of the gas control valve, it is difficult to find a suitable balance point, which makes operation difficult and extremely unfavorable for safe production.

[0070] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the present invention.

Claims

1. A hot standby method for a high-solid oil slurry heating furnace of a coal direct liquefaction device, characterized in that: The heating furnace has two independently operated furnaces, and when the heating furnace is operating normally, one of the two furnaces is used as an operating furnace to heat the oil slurry, and the other is used as a standby furnace; The standby furnace is equipped with corresponding standby furnace tubes, and the operating furnace is equipped with corresponding operating furnace tubes, so as to be used for heating the oil slurry during normal operation; The inlet end of the standby furnace tube is connected to the flushing oil supply pipe and the heating furnace inlet main pipe through the first branch pipe and the second branch pipe respectively, and the inlet end of the operating furnace tube is connected to the flushing oil supply pipe and the heating furnace inlet main pipe through the third branch pipe and the fourth branch pipe respectively; The outlet end of the standby furnace tube is connected to the flushing oil return pipe and the heating furnace outlet main pipe through the fifth branch pipe and the sixth branch pipe respectively, and the outlet end of the operating furnace tube is connected to the flushing oil return pipe and the heating furnace outlet main pipe through the seventh branch pipe and the eighth branch pipe respectively; The hot standby method comprises the following steps: S1) operating a valve to cut off the connection between the inlet end of the spare furnace tube and the inlet main pipe of the heating furnace and the connection between the outlet end of the spare furnace tube and the outlet main pipe of the heating furnace; S2) operating the valve to connect the inlet end of the standby furnace tube with the flushing oil supply pipe and the outlet end of the standby furnace tube with the flushing oil return pipe, so that the flushing oil fills the standby furnace tube and then returns to the flushing oil return pipe to prevent the standby furnace tube from overpressure; S3) igniting the burner of the radiation chamber of the standby furnace, and controlling the temperature of the standby furnace to a preset temperature by adjusting the flow rate of the gas used as fuel; S4) After the temperature of the standby furnace reaches the preset temperature, the supply flow rate of the flushing oil delivered to the standby furnace tube and / or the return flow rate of the flushing oil entering the flushing oil return pipe are adjusted to control the pressure of the standby furnace tube to the preset pressure, so as to achieve the purpose of constant temperature and constant pressure standby.

2. The hot standby method according to claim 1, characterized in that: The hot standby method also includes step S5) when the operating furnace fails or stops working due to routine switching, the flushing oil return from the spare furnace tube is first switched from the flushing oil return pipe to the heating furnace outlet main pipe, and the flushing oil flow entering the spare furnace tube is increased, the burners of the spare furnace are increased, and then the standby furnace is heated to the required switching temperature as required before the switching operation is performed.

3. The hot standby method according to claim 1 or 2, characterized in that: The first branch pipe is provided with a spare furnace pipe flushing oil supply hand valve, the second branch pipe is provided with a spare furnace pipe inlet regulating valve front hand valve, and the inlet end of the spare furnace pipe is also provided with a spare furnace pipe inlet regulating valve and a spare furnace pipe inlet regulating valve rear hand valve in sequence along the logistics direction; The third branch pipe is provided with a manual valve for supplying flushing oil to the operating furnace tube, the fourth branch pipe is provided with a manual valve before the operating furnace tube inlet regulating valve, and the inlet end of the operating furnace tube is also provided with an operating furnace tube inlet regulating valve and a manual valve after the operating furnace tube inlet regulating valve in sequence along the logistics direction.

4. The hot standby method according to claim 3, characterized in that: The fifth branch pipe is provided with a spare furnace pipe flushing oil return hand valve, and the sixth branch pipe is provided with a spare furnace pipe outlet hand valve; The seventh branch pipe is provided with a running furnace pipe flushing oil return manual valve, and the eighth branch pipe is provided with a running furnace pipe outlet manual valve.

5. The hot standby method according to claim 4, characterized in that: In step S1, the front hand valve at the inlet of the spare furnace tube and the rear hand valve at the inlet regulating valve of the spare furnace tube of the spare furnace are closed to ensure that the spare furnace tube is completely removed; In step S2, open the manual valve for supplying flushing oil to the spare furnace tube, open the inlet regulating valve of the spare furnace tube, open the manual valve behind the inlet regulating valve of the spare furnace tube, so that the flushing oil fills the spare furnace tube, open the flushing oil return manual valve behind the spare furnace, so that the flushing oil returns to the flushing oil return main pipe.

6. The hot standby method according to claim 5, characterized in that: In step S4, after the standby furnace temperature reaches the preset temperature, the standby furnace tube flushing oil supply manual valve and the standby furnace tube flushing oil return manual valve are adjusted again to control the standby furnace tube pressure at the preset pressure to achieve the purpose of constant temperature and pressure standby.

7. The hot standby method according to any one of claims 1 to 6, characterized in that: The oil slurry has an ash content of 4%-8%, a solid content of 18%-22%, and a n-hexane insoluble matter content of 37%-45%.

8. The hot standby method according to claim 7, characterized in that: The preset temperature in step S3 is 230±5° C., and the preset pressure in step S4 is 0.9±0.1 MPa.

9. The hot standby method according to any one of claims 1 to 8, characterized in that: The heating furnace is modified from an original heating furnace, wherein the two furnaces of the original heating furnace share a convection chamber and a flue. During the modification, two partition walls are added to the convection chamber of the original heating furnace to completely separate the convection chamber of the original heating furnace from the middle position to form two independent convection chambers; at the same time, the flue gas of the radiation chambers of the two furnaces enters the respective convection chambers, and a gate valve is provided in the flue of each furnace, so that the combustion conditions of the two furnaces can be controlled separately by controlling the gate valve on the flue, so that the two furnaces can operate separately without interfering with each other.

10. The hot standby method according to claim 9, characterized in that: In order to facilitate the decoking of the removed furnace, during the reconstruction, the bent pipe part of the furnace tube in the furnace of the original heating furnace is moved from the furnace to the outside of the furnace, and connected with a flange connection that is easy to disassemble, so that the bent pipe part can be disassembled to decoke the furnace tube in sections.

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