An electric heating device and heating system using liquid sulfur as a medium

Abstract

The utility model provides a kind of electric heating device and heating system with liquid sulfur as medium, belong to electric heater technical field, including pressure tank body and the heat exchange coil of being arranged in the upper region in pressure tank body, the bottom in the pressure tank body has liquid sulfur and the electric heater of heating liquid sulfur to produce sulfur vapor, and sulfur vapor rises and exchanges heat with heat exchange coil after condensation into liquid sulfur, under the action of gravity, return to the bottom of pressure tank body.The utility model uses sulfur as intermediate heat transfer medium, realizes boiling enhanced heat transfer on the surface of electric heater, can let electric heat quickly transfer to sulfur;On the surface of heat exchange coil, realize condensation enhanced heat transfer, can let the heat carried by sulfur vapor quickly transfer to the medium to be heated, by phase change heat transfer, greatly improve heat transfer capacity.

Description

Technical Field

[0001] This utility model relates to the field of electric heater technology, specifically an electric heating device and heating system using liquid sulfur as a medium. Background Technology

[0002] Petrochemical heating furnaces are key equipment used for heating media in petrochemical production. They mainly generate heat by burning fossil fuels and transfer heat through radiation, convection and conduction to achieve efficient heating. However, the combustion of fossil fuels causes carbon emissions. Replacing fossil fuel combustion with new energy clean electric heating is one of the important ways for the petrochemical industry to reduce carbon emissions.

[0003] Currently, conventional electric heaters are used to directly heat the working fluid (such as feedstock oil, hydrogenated oil, heavy oil, etc.), which can easily lead to overheating of the heating rod surface, resulting in decomposition of the working fluid and coking.

[0004] To address this issue, existing technologies employ elemental sulfur as an intermediate heat transfer medium. The core of this approach is to use electric heating to sublimate liquid sulfur into gaseous sulfur (sulfur vapor), which is then used to heat the working medium. This avoids the problems caused by direct heating with an electric heating rod. For example, the applicant filed a utility model patent in 2023 with application number 2023110556836. Utility Model Content

[0005] The purpose of this invention is to provide an electric heating device and system that uses liquid sulfur as a medium. By using saturated sulfur vapor as the heating medium, it avoids the problems of surface overheating, decomposition of the working medium, and coking that occur when conventional electric heaters directly heat the working medium.

[0006] The technical solution adopted by this utility model to achieve the above-mentioned technical objectives is as follows: an electric heating device using liquid sulfur as a medium, comprising a pressure-resistant tank and a heat exchange coil disposed in the upper region of the pressure-resistant tank. The bottom of the pressure-resistant tank contains liquid sulfur and an electric heater for heating the liquid sulfur to generate sulfur vapor. The sulfur vapor rises and exchanges heat with the heat exchange coil, then condenses into liquid sulfur and returns to the bottom of the pressure-resistant tank under the action of gravity.

[0007] As an optimized solution for the aforementioned electric heating device using liquid sulfur as a medium, the pressure tank is filled with inert gas or evacuated.

[0008] As another optimized solution for the above-mentioned electric heating device using liquid sulfur as a medium, the pressure tank has an external insulation layer.

[0009] As another optimized solution for the above-mentioned electric heating device using liquid sulfur as a medium, a gas-liquid separation component is horizontally arranged inside the pressure tank, and the gas-liquid separation component divides the inner part of the pressure tank into an upper heating zone and a lower liquid sulfur zone. The heat exchange coil is located in the heating zone, and the electric heater and liquid sulfur are located in the liquid sulfur zone. The generated sulfur vapor enters the heating zone after passing through the gas-liquid separation component and exchanges heat with the heat exchange coil.

[0010] As another optimized solution for the above-mentioned electric heating device using liquid sulfur as a medium, the gas-liquid separation component is a gas-liquid separator with at least one stage.

[0011] As another optimized embodiment of the above-mentioned electric heating device using liquid sulfur as a medium, the heat exchange coil has an inlet pipe for the heated liquid and an outlet pipe for the heated liquid.

[0012] As another optimized solution for the above-mentioned electric heating device using liquid sulfur as a medium, the heat exchange coil is made of a material with high heat transfer and that does not react with sulfur.

[0013] As another optimized solution for the above-mentioned electric heating device using liquid sulfur as a medium, the heat exchange coils are vertically distributed in the pressure tank to form heat exchange channels between adjacent coils.

[0014] As another optimized solution for the aforementioned electric heating device using liquid sulfur as a medium, the top of the pressure tank is an upward-convex arc shape.

[0015] An electric heating system using liquid sulfur as a medium includes the aforementioned electric heating device and a controller. A pressure sensor is installed inside the pressure-resistant tank of the electric heating device to monitor its internal pressure. The pressure sensor transmits the monitoring data to the controller, which then controls the start and stop of the electric heater based on the monitoring data.

[0016] The working principle of this utility model is as follows: When heating of the working medium is required, the electric heater is activated to heat the liquid sulfur at the bottom of the pressure tank to a boiling state, causing the sulfur inside the tank to be in a gas-liquid two-phase state. Since the heating process inside the tank is constant volume, the pressure will continuously increase. When the pressure rises to P1 (e.g., 1 MPa, at which point the temperature of the liquid sulfur and sulfur vapor is 648.9℃), the electric heater is turned off to stop heating. The sulfur vapor generated by boiling rises upwards, and after passing through the gas-liquid separation component to remove the carried droplets, it enters the upper space and exchanges heat with the heated liquid flowing through the heat exchange coil. After condensation, it returns to the bottom of the tank. During this process, due to the release of heat from the condensation of sulfur vapor, its volume decreases, and the pressure inside the tank will decrease. When the pressure inside the tank is lower than P2 (e.g., 0.95 MPa), the electric heater is activated again to raise the pressure inside the tank. When the pressure rises to P1, the electric heater is turned off again. The pressure signal detected by the pressure sensor is used as the start-stop control logic for the electric heater.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1) Constant volume heating brings sulfur to a gas-liquid two-phase state, at which point the sulfur vapor in the tank is essentially saturated, and its pressure and temperature are directly correlated. Conventional electric heaters typically use thermocouples on the surface of the heating rod or in the heated medium, using the measured temperature signal as the basis for control. Temperature measurements often have a lag and can result in uneven local temperature distribution; accurate measurements often require multiple measuring points. Pressure signals, on the other hand, respond much faster and do not require multiple measuring points. Therefore, this invention uses a pressure signal instead of a temperature signal as the primary basis for controlling the electric heater, enabling more convenient, faster, and more precise control. 2) Using sulfur as an intermediate heat transfer medium, boiling-enhanced heat transfer is achieved on the surface of the electric heater, which allows the electric heat to be quickly transferred to the sulfur; condensation-enhanced heat transfer is achieved on the surface of the heat exchange coil, which allows the heat carried by the sulfur vapor to be quickly transferred to the heated medium. Through phase change heat transfer, the heat transfer capacity is greatly improved. 3) Sulfur has a saturated vapor pressure of about 0.1-1.0 MPa at 444-648℃, which is a relatively suitable saturated vapor pressure and temperature. By using the pressure signal as the control signal, the pressure can be allowed to fluctuate within a very small range, so that the temperature of the sulfur vapor side in the upper heating zone of the tank can be controlled at an approximately constant temperature. The heat generated by the lower electric heater can be continuously transferred to the heated liquid, thereby avoiding problems such as overheating cracking and coking that occur when the electric heating rod directly heats the working medium. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of this utility model; Reference numerals: 1. Pressure tank, 101. Liquid sulfur zone, 102. Heating zone, 2. Heat exchanger, 201. Inlet pipe for heated liquid, 202. Outlet pipe for heated liquid, 203. Heat exchange channel, 3. Electric heater, 4. Pressure sensor, 5. Controller, 6. Gas-liquid separation assembly. Detailed Implementation

[0019] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. Parts not described in the following embodiments of the present invention are all considered to be prior art known or should be known by those skilled in the art, such as the structure, model and control of heat exchangers, heaters, liquid sulfur pumps, cyclone separators, cyclone plate separators, baffle plate demisters and wire mesh demisters, etc.

[0020] Example 1 An electric heating device using liquid sulfur as a medium, such as... Figure 1As shown, it includes a pressure tank 1 and a heat exchange coil 2 disposed in the upper region of the pressure tank 1. The heat exchange coil 2 can be an existing heat exchange coil, and has a heated liquid inlet pipe 201 and a heated liquid outlet pipe 202 extending to the outside of the pressure tank 1. The liquid to be heated enters the pressure tank 1 through the heated liquid inlet pipe 201, exchanges heat with sulfur vapor, and then flows out from the heated liquid outlet pipe 202. The heat exchange coil 2 is made of a material with high heat transfer and that does not react with sulfur. The pressure tank 1 is generally cylindrical in shape, with an arc-shaped bottom forming a liquid sulfur zone 101. After elemental sulfur is heated to form liquid sulfur, it is located in this zone. The top of the tank is a convex arc shape with a high center and low edges. This convex arc structure allows sulfur vapor to rise, touch and condense, and then flow back from the edge along the side wall of the pressure tank 1 to the bottom liquid sulfur zone 101, thus avoiding the condensed liquid sulfur from falling directly onto the surface of the heat exchange coil 2 as much as possible. The bottom of the pressure tank 1 is preferably concave arc-shaped. The heating part of the electric heater 3 is located in the liquid sulfur zone 101 and is covered by liquid sulfur. The pressure tank 1 is filled with inert gas or evacuated, and has an external insulation layer. The bottom of the pressure tank 1 contains liquid sulfur and an electric heater 3 that heats the liquid sulfur to generate sulfur vapor. The liquid sulfur is formed by melting elemental sulfur or sulfur, and its temperature is generally 130-200℃. After the electric heater 3 heats the liquid sulfur, it continuously generates sulfur vapor. The sulfur vapor rises and exchanges heat with the heat exchange coil 2, then condenses into liquid sulfur, which returns to the bottom of the pressure tank 1 under the action of gravity, completing the cycle.

[0021] The above are the basic embodiments of this utility model. Further improvements, optimizations, and limitations can be made based on the above to obtain the following embodiments: Example 2 This embodiment is an improvement on embodiment 1. Its main structure is the same as that of embodiment 1, but the improvement lies in: [The following is a more detailed description of the improvement.] Figure 1 As shown, a gas-liquid separation component 6 is horizontally arranged inside the pressure tank 1, and the gas-liquid separation component 6 divides the interior of the pressure tank 1 into an upper heating zone 102 and a lower liquid sulfur zone 101. The heat exchange coil 2 is located in the heating zone 102, and the electric heater 3 and liquid sulfur are located in the liquid sulfur zone 101. The generated sulfur vapor enters the heating zone 102 after passing through the gas-liquid separation component 6 and exchanges heat with the heat exchange coil 2. Since sulfur vapor carries liquid sulfur much more readily than water vapor carries liquid droplets, and is therefore much more difficult to separate from liquid sulfur, traditional single-stage separation techniques are not very effective at separating sulfur droplets carried by saturated sulfur vapor. Therefore, in this embodiment, the gas-liquid separation component 6 is at least a single-stage gas-liquid separator, preferably using a combination of four different gas-liquid separators, so that the dryness of the sulfur vapor can reach over 97%. Following a bottom-up order, the gas-liquid separation is divided into four stages: The first stage consists of at least four sets of cyclone separators, and these cyclone separators rotate in the same direction. The second stage is a cyclone separator, and the cyclone separator is set to have the cyclone direction exactly opposite to that of the first-stage cyclone separator. The third stage is a baffle plate separator; The fourth stage is a wire mesh demister; Sulfur vapor passes through the first-stage cyclone separator, the second-stage cyclone plate separator, the third-stage baffle plate separator, and the fourth-stage wire mesh demister in sequence before entering the heating zone 102 to exchange heat with the heat exchange coil 2.

[0022] The principle of the above four-level separation is as follows: The first stage uses a cyclone separator. When saturated sulfur vapor is first generated, it carries the largest number of droplets. Therefore, at least four sets of cyclone separators arranged in a ring are used to initially separate the droplets. The saturated sulfur vapor generated by electric heating first enters the cyclone separator. Through centrifugal force, the large droplets are collected and discharged from the bottom. The saturated sulfur vapor carries some small droplets and is discharged obliquely upward from the upper horizontal position of the cyclone separator. The saturated sulfur vapor discharged from the cyclone separator is in a swirling state. During the collision of the airflow, some of the small droplets carried by it merge into large droplets, which separate from the gas under the action of gravity and centrifugal force. At the same time, the gas discharged from these cyclone separators gradually transforms from multiple small swirling streams into a large swirling stream during the upward process. The second stage uses a cyclone separator. The cyclone separator is set to have the cyclone direction opposite to that of the first-stage cyclone separator. The saturated sulfur vapor flow direction is forcibly changed by the cyclone separator. During this process, the airflow collides violently with the cyclone plate, and some small droplets merge into large droplets during the collision and break away from the airflow. An arc-shaped guide groove is provided on the outlet side of the cyclone separator to intercept some small droplets, which then flow into the central channel of the cyclone separator and are discharged from the liquid-repellent tube. The third stage employs a baffle plate separator. After removal by the first two stages of separators, the liquid content of the saturated sulfur vapor has been greatly reduced. At this point, the saturated sulfur vapor carrying a lower liquid volume and smaller droplets enters the baffle plate separator for further separation, which can further reduce the amount of liquid sulfur entrained in the sulfur vapor. At the same time, the baffle plate separator can uniformly distribute the airflow, thus rectifying the steam flow field after the swirling collisions of the first two stages. The fourth stage uses a wire mesh demister. After the sulfur vapor has been deliquerated and rectified by the third stage separator, it enters the wire mesh demister, which can remove the extremely fine droplets it carries, ultimately making the sulfur vapor appear in a dry saturated state.

[0023] Because liquid sulfur has a high viscosity, arbitrarily changing the order of the four-stage gas-liquid separators will lead to a decrease in separation efficiency and may even cause the separators to become clogged.

[0024] Example 3 This embodiment is an improvement on embodiment 1. Its main structure is the same as that of embodiment 1, but the improvement lies in: [The following is a more detailed description of the improvement.] Figure 1 As shown, the heat exchange coils 2 are vertically bent and distributed inside the pressure tank 1 to form a vertical heat exchange channel 203 for sulfur vapor to pass through between adjacent tubes. This vertically arranged tube structure can minimize the adhesion of small droplets carried by sulfur vapor to its surface.

[0025] Example 4 An electric heating system using liquid sulfur as a medium, such as Figure 1 As shown, the device includes the aforementioned electric heating device and a controller 5. A pressure sensor 4 is installed inside the pressure tank 1 of the electric heating device to monitor its internal pressure. The pressure sensor 4 transmits the monitoring data to the controller 5, and the controller 5 controls the start and stop of the electric heater 3 based on the monitoring data.

[0026] The working process is as follows: When the working medium needs to be heated, the electric heater 3 is started to heat the liquid sulfur at the bottom of the pressure tank 1 to a boiling state, so that the sulfur in the tank is in a gas-liquid two-phase state. Since the heating process in the tank is constant volume, the pressure will continue to rise. When the pressure rises to P1 (e.g., 1 MPa, at which time the temperature of liquid sulfur and sulfur vapor is 648.9℃), the electric heater 3 is turned off and the heating is stopped. The sulfur vapor generated by boiling rises and, after passing through the gas-liquid separation component 6 to remove the carried droplets, enters the upper space and exchanges heat with the heated liquid flowing through the heat exchange coil 2. After condensation, it returns to the bottom of the tank. During this process, due to the release of heat from the condensation of sulfur vapor, the volume decreases and the pressure in the tank will decrease. When the pressure in the tank is lower than P2 (e.g., 0.95 MPa), the electric heater 3 is started again to raise the pressure in the tank. When the pressure rises to P1, the electric heater 3 is turned off again. The pressure signal detected by the pressure sensor 4 is used as the start and stop control logic of the electric heater 3.

Claims

1. An electric heating device using liquid sulfur as a medium, comprising a pressure-resistant tank (1) and a heat exchange coil (2) disposed in the upper region of the pressure-resistant tank (1), characterized in that: The bottom of the pressure tank (1) contains liquid sulfur and an electric heater (3) that heats the liquid sulfur to generate sulfur vapor. The sulfur vapor rises and exchanges heat with the heat exchange coil (2) and then condenses into liquid sulfur, which returns to the bottom of the pressure tank (1) under the action of gravity.

2. The electric heating device using liquid sulfur as a medium according to claim 1, characterized in that: The pressure tank (1) is filled with inert gas or evacuated.

3. The electric heating device using liquid sulfur as a medium according to claim 1, characterized in that: The pressure tank (1) has an external heat insulation layer.

4. The electric heating device using liquid sulfur as a medium according to claim 1, characterized in that: The pressure tank (1) is horizontally equipped with a gas-liquid separation component (6), which divides the interior of the pressure tank (1) into an upper heating zone (102) and a lower liquid sulfur zone (101). The heat exchange coil (2) is located in the heating zone (102), and the electric heater (3) and liquid sulfur are located in the liquid sulfur zone (101). The generated sulfur vapor enters the heating zone (102) after passing through the gas-liquid separation component (6) and exchanges heat with the heat exchange coil (2).

5. The electric heating device using liquid sulfur as a medium according to claim 4, characterized in that: The gas-liquid separation component (6) is at least one stage of gas-liquid separator.

6. The electric heating device using liquid sulfur as a medium according to claim 1, characterized in that: The heat exchange coil (2) has a heated liquid inlet pipe (201) and a heated liquid outlet pipe (202).

7. The electric heating device using liquid sulfur as a medium according to claim 1, characterized in that: The heat exchange coil (2) is made of a material with high heat transfer and that does not react with sulfur.

8. The electric heating device using liquid sulfur as a medium according to claim 1, characterized in that: The heat exchange coils (2) are vertically distributed within the pressure tank (1) to form heat exchange channels (203) between adjacent tubes.

9. An electric heating device using liquid sulfur as a medium according to claim 1, characterized in that: The top of the pressure tank (1) is an upward-convex arc shape.

10. An electric heating system using liquid sulfur as a medium, characterized in that: The device includes an electric heating device as described in any one of claims 1-9 and a controller (5). A pressure sensor (4) is provided inside the pressure tank (1) of the electric heating device to monitor its internal pressure. The pressure sensor (4) transmits the monitoring data to the controller (5), and the controller (5) controls the start and stop of the electric heater (3) based on the monitoring data.

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