Electric radiation convection external circulation cylindrical heating furnace

Abstract

The utility model belongs to the technical field of petroleum chemical heating furnace, relates to a kind of electric radiation convection outer circulation cylinder heating furnace.From outside to inside, it is in order: cylinder furnace steel structure, cylinder furnace wallboard, heat insulation lining.Cylinder furnace steel structure is used to support the whole shell, and cylinder furnace steel structure is connected with cylinder furnace wallboard by welding, and heat insulation lining is arranged in the inside of cylinder furnace wallboard, to play the role of heat insulation and heat preservation.Cylinder furnace is divided into two parts, and the upper part is convection chamber, and the lower part is radiation chamber.Convection chamber is cuboid shape, and internal furnace tube is arranged in multiple layers in horizontal direction, and furnace tube mainly receives convection heat transfer.Radiation chamber is cylindrical, and furnace tube is distributed along the inner wall of cylinder, and furnace tube mainly receives radiation heat transfer.The utility model can completely replace oil or gas process heating furnace in petrochemical industry, and is suitable for heating of various process media.Especially for new project, and existing gas or oil heating furnace is transformed into electric heating furnace, with significant advantages.

Description

Technical Field

[0001] This utility model belongs to the field of petrochemical heating furnace technology, and relates to an electric radiation convection external circulation cylindrical heating furnace for heating various process media in petrochemicals. Background Technology

[0002] In the current petrochemical industry, most process heating furnaces are gas-fired. However, gas-fired furnaces have many drawbacks, generating significant carbon emissions and putting considerable pressure on the environment. Furthermore, they emit pollutants such as nitrogen oxides during operation, failing to meet environmental protection requirements.

[0003] In addition, gas-fired heating furnaces require complex combustion control systems, which increases the equipment's footprint and poses a safety hazard of gas leaks, thus posing a potential threat to production safety.

[0004] In contrast, the electric radiation convection external circulation cylindrical heater of this invention can completely replace fuel oil or gas process heaters in the petrochemical industry and is suitable for heating various process media. It has significant advantages, especially for new projects and for converting existing fuel oil or gas heaters into electric heaters. Utility Model Content

[0005] This utility model provides an electric radiation convection external circulation cylindrical heating furnace. The electric heating furnace uses a variable frequency fan to force the circulation of internal carbon dioxide inert gas to achieve radiation and convection dual heat transfer, which enhances the overall thermal intensity of the electric heating furnace.

[0006] The technical solution adopted in this utility model is as follows:

[0007] An electrically radiant convection external circulation cylindrical heater furnace comprises, from the outside to the inside: a cylindrical furnace steel structure, a cylindrical furnace wall panel, and a heat-insulating lining. The cylindrical furnace steel structure supports the entire shell and is welded to the cylindrical furnace wall panel. A heat-insulating lining is installed on the inner side of the cylindrical furnace wall panel for heat insulation. The cylindrical furnace is divided into two parts: an upper convection chamber and a lower radiation chamber. The convection chamber is cubic in shape, with multiple layers of furnace tubes arranged horizontally inside, primarily receiving heat from convection. The radiation chamber is cylindrical, with furnace tubes distributed along the inner wall of the cylinder, primarily receiving heat from radiation.

[0008] The top of the convection chamber is the furnace top air duct, which is connected to the fan inlet through the air duct, and the fan outlet is connected to the annular air duct at the bottom of the heating furnace.

[0009] The electric heating tubes of the radiant chamber are inserted into the chamber from the top to provide heat to the furnace. A flange sleeve at the top of the radiant chamber communicates with the inner cavity of the chamber. The electric heating tubes pass through this sleeve into the chamber, and the flange caps at the ends of the heating tubes are bolted to the flanges of the sleeves. An explosion-proof junction box is located at the end of the electric heating tube, with control and power inlets. Temperature sensing elements are installed on the electric heating tubes.

[0010] The entire electric radiant cylindrical furnace is a fully enclosed structure, filled with carbon dioxide or other inert protective gases to protect the electric heating elements from oxidation and to facilitate the transfer of convective heat.

[0011] Further features include a heating resistance wire as the inner core of the electric heating tube, a high-alloy steel sleeve or a material selected according to the characteristics of the heating medium, and magnesium oxide powder filling the space between the resistance wire and the sleeve for insulation, ensuring the safe and reliable operation of the electric heating tube.

[0012] A further feature is the presence of an annular air duct at the furnace bottom, with multiple airflow channels between the annular air duct and the furnace interior cavity. An inert protective gas (such as carbon dioxide) is drawn in from the top air duct of the convection chamber by a variable frequency fan and blown into the furnace body from the bottom, achieving forced circulation of the gas within the furnace. This forces convective heat exchange between the gas and the furnace tubes, improving heat exchange efficiency. The inert gas moves upwards in the radiant chamber, absorbing heat from the electric heating tubes, and in the convection chamber, it transfers heat primarily to the convection furnace tubes via convection.

[0013] A further feature is that the electric heating element is equipped with a temperature sensing element and an over-temperature interlock protection system. When the temperature exceeds the set temperature, the system will automatically stop heating to prevent overheating damage to the equipment. Simultaneously, temperature sensing elements are installed at the medium inlet and outlet. By monitoring the inlet and outlet temperatures in real time, the power of the heating element is adjusted to achieve precise temperature control, meeting the process requirements with high temperature control demands.

[0014] Furthermore, this patent protects furnace tubes in various arrangements, such as spiral coils and vertical coils, to meet the heating requirements of different process media and equipment space layout requirements.

[0015] The beneficial effects of this utility model are:

[0016] The material enters the convection furnace tubes from the top of the convection chamber, absorbing heat as it flows within the tubes. The furnace tubes in the convection chamber exchange heat with high-temperature inert carbon dioxide gas, initially raising the material's temperature. Subsequently, the material enters the radiation chamber via an oil transfer line. Electric heating tubes are arranged within the radiation chamber; when energized, these tubes generate heat, transferring it to the furnace tubes via radiation, and then from the furnace tubes to the medium, further raising its temperature. This device is suitable for both new construction and the conversion of existing gas or oil-fired furnaces into electric furnaces. During the conversion process, it maximizes the use of existing components such as the radiation chamber, convection chamber, furnace tubes, furnace steel structure, and insulation lining, achieving electrification with minimal investment.

[0017] By adding a circulating fan, the entire heating furnace undergoes both radiative and forced convection heat transfer, increasing the furnace's volumetric thermal intensity and reducing equipment costs. It is low-carbon, environmentally friendly, clean, pollution-free, highly safe, easy to adjust, and starts up quickly. Its high thermal efficiency, reaching approximately 98%, far exceeds that of traditional gas-fired heating furnaces, significantly improving energy utilization efficiency. Attached Figure Description

[0018] Figure 1 This is a vertical sectional view of the present invention;

[0019] Figure 2 This is a horizontal sectional view of the present invention;

[0020] Figure 3 This is a partial enlarged view of the present invention;

[0021] In the diagram: 1. Furnace top air duct; 2. Medium inlet; 3. Medium outlet; 4. Radiant chamber; 5. Electric heating tube; 6. Steel structure;

[0022] 7 Furnace wall panel; 8 Insulation lining; 9 Furnace tube; 10 Furnace bottom ring air duct; 11 Variable frequency fan; 12 Air duct; 13 Convection chamber;

[0023] 14 Flange cover; 15 Flange; 16 Sleeve; 17 Temperature sensing element; 18 Explosion-proof junction box; 19 Control inlet;

[0024] 20 power inlet ports. Detailed Implementation

[0025] The specific embodiments of this utility model are described in detail below with reference to the technical solution and accompanying drawings.

[0026] The electric radiant convection external circulation cylindrical heating furnace consists of a steel structure 6, furnace wall panels 7, and an insulation lining 8, arranged sequentially from the outside to the inside. The steel structure 6 provides support for the entire furnace. The exterior of the furnace wall panels 7 is welded to the steel structure 6, and the interior of the furnace wall panels 7 is connected to the insulation lining 8 via insulation nails. The insulation lining 8 effectively reduces heat loss and improves the thermal efficiency of the equipment. The cylindrical furnace is mainly divided into two parts: the lower part is cylindrical, with furnace tubes 9 distributed along the inner wall of the cylinder. The furnace tubes 9 mainly receive radiant heat transfer; this part is called the radiation chamber 4. The upper part is cubic, with multiple layers of furnace tubes 9 arranged horizontally inside. The furnace tubes 9 mainly receive convective heat transfer; this part is called the convection chamber 13. The medium inlet 2 is located in the convection chamber 13. The medium enters the convection furnace tubes 9 in the convection chamber 13 from the medium inlet 2 for heating. In the convection chamber, it undergoes convective heat exchange with carbon dioxide. The heated medium then enters the radiant furnace tubes in the radiation chamber 4 to continue receiving radiant heat transfer from the electric heating tubes 5. The heated medium flows out from the top medium outlet 3 of the radiation chamber 4.

[0027] The top of the convection chamber 13 is the furnace top air duct 1, which is connected to the inlet of the variable frequency fan 11 via the air duct 12, and the outlet of the fan is connected to the furnace bottom ring air duct 10.

[0028] An electric heating element 5 is inserted into the radiation chamber 4 from the top, providing heat to the entire furnace. A sleeve 16 is installed at the top of the radiation chamber 4, with a flange 15 at the top. The sleeve 16 communicates with the inner cavity of the radiation chamber 4. The electric heating element 5 passes through the sleeve 16 into the interior of the radiation chamber. The flange cover 14 at the end of the electric heating element is bolted to the flange 15 of the sleeve. An explosion-proof junction box 18 is installed at the end of the electric heating element 5, with a control inlet 19 and a power inlet 20. A temperature sensing element 17 is installed on the electric heating element.

[0029] Material heating process: The process medium enters the furnace tube 9 in the convection chamber 13 from the medium inlet 2 for heat exchange, absorbing the heat transferred by the high-temperature inert carbon dioxide gas, thus initially raising the medium temperature. Then, the medium enters the radiation chamber 4 for radiant heat exchange. The electric heating tube 5 heats up after being energized, transferring heat to the furnace tube 9 via radiation, and then to the medium, further raising its temperature. The heated process medium flows out from the medium outlet 3.

[0030] Power supply and control connection: Control inlet 19 and power inlet 20 are connected to the electrical control system to supply power to the electric heating tube 5 and receive signals from instruments such as temperature and pressure gauges. Electricity is supplied to the electric heating tube 5 through the explosion-proof junction box 18, causing the heating tube to heat up after power is applied. The medium enters the furnace tube 9 through inlet 2, flows inside the furnace tube, and absorbs heat. The heat comes from the radiant and convective heat of the electric heating tube 5. The heated medium flows out from outlet 3. The heating furnace cavity is a sealed structure, filled with the inert protective gas carbon dioxide.

[0031] Gas circulation system operation: A furnace bottom annular air duct 10 is arranged at the furnace bottom, and multiple airflow channels connect the annular air duct to the furnace inner cavity. The airflow channels are at a certain angle to the furnace body. After the inert gas is injected into the furnace body, it enters a turbulent disturbance state, and the flow state is as follows: Figure 1 As shown, the variable frequency fan 11 draws in inert protective gas carbon dioxide from the furnace top air duct 1, passes through the air duct 12, and then blows the carbon dioxide gas into the furnace body from the furnace bottom ring air duct 10, realizing forced circulation of gas in the furnace, enabling forced convection heat exchange between the gas and the furnace tubes, and improving the heat exchange effect.

Claims

1. An electric radiation convection external circulation cylindrical heating furnace, characterized in that, From the outside in, the components are: cylindrical furnace steel structure, cylindrical furnace wall panels, and heat insulation lining. The cylindrical furnace steel structure supports the entire shell and is welded to the cylindrical furnace wall panels. The inner side of the cylindrical furnace wall panels is lined with heat insulation lining for heat insulation. The cylindrical furnace is divided into two parts: an upper convection chamber and a lower radiation chamber. The convection chamber is cubic in shape, with multiple layers of furnace tubes arranged horizontally inside. The furnace tubes mainly receive heat transfer through convection. The radiation chamber is cylindrical, with furnace tubes distributed along the inner wall of the cylinder. The furnace tubes mainly receive heat transfer through radiation. The top of the convection chamber is the furnace top air duct, which is connected to the fan inlet through the air duct, and the fan outlet is connected to the annular air duct at the bottom of the heating furnace. The electric heating tubes of the radiant chamber are inserted into the radiant chamber from the top to provide heat to the heating furnace; the top of the radiant chamber is equipped with a flange sleeve that communicates with the inner cavity of the radiant chamber, and the electric heating tubes pass through the sleeve to enter the radiant chamber. The flange cover at the end of the electric heating tube is bolted to the flange of the sleeve; the end of the electric heating tube is equipped with an explosion-proof junction box, which has a control inlet and a power inlet; the electric heating tube is equipped with a temperature measuring element. The entire electric radiant cylindrical furnace is a fully enclosed structure, filled with carbon dioxide or inert protective gas to protect the electric heating elements from oxidation and to facilitate the transfer of convective heat.

2. The electric radiation convection external circulation cylindrical heating furnace according to claim 1, characterized in that, The inner core of the electric heating element is a heating resistance wire, and the sleeve is made of high alloy steel or selected according to the characteristics of the heating medium. The space between the resistance wire and the sleeve is filled with magnesium oxide powder for insulation treatment to ensure the safe and reliable operation of the electric heating element.

3. The electric radiation convection external circulation cylindrical heating furnace according to claim 1, characterized in that, The furnace bottom is equipped with an annular air duct, and multiple airflow channels are provided between the annular air duct and the furnace body cavity. Inert protective gas is drawn in from the air duct at the top of the convection chamber by a variable frequency fan and blown into the furnace body from the bottom of the furnace to achieve forced circulation of gas in the furnace. This enables forced convection heat exchange between the gas and the furnace tubes, improving heat exchange efficiency. The inert gas moves upward in the radiation chamber to absorb heat from the electric heating tubes, and in the convection chamber, the heat is transferred to the convection furnace tubes mainly by convection heat transfer.

4. The electroradiation convection external circulation cylindrical heating furnace according to claim 1, characterized in that, The electric heating element is equipped with a temperature sensing element and an over-temperature interlock protection system. When the temperature exceeds the set temperature, the system will automatically stop heating to prevent the equipment from overheating and being damaged. At the same time, temperature sensing elements are installed at the medium inlet and outlet. By monitoring the inlet and outlet temperatures in real time, the power of the heating element is adjusted to achieve precise temperature control and meet the process requirements with high temperature control requirements.

5. The electroradiation convection external circulation cylindrical heating furnace according to claim 1, characterized in that, The furnace tubes are arranged in spiral or vertical coil form to meet the heating requirements of different process media and the space layout requirements of the equipment.

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