System for on-line conversion of sodium source into heat energy and hydrogen

Abstract

Disclosed in the present invention is a system for the on-line conversion of a sodium source into heat energy and hydrogen. A reactor is filled with hydrogen prior to a reaction, and liquid sodium and water vapor are injected into the reactor; when the water vapor comes into contact with the liquid sodium, a combustion reaction occurs to generate hydrogen and sodium hydroxide, and the water vapor which does not participate in the reaction absorbs heat to form high-temperature water vapor having a higher temperature; the temperature of a gas mixture of the hydrogen and the high-temperature water vapor is lower than 70°C after passing through a heat exchanger, the high-temperature water vapor is condensed into water and flows back to the bottom of the reactor, and the hydrogen is discharged from a hydrogen collecting pipe via a pressure relief valve; and a drain valve is controlled during the combustion reaction, and the height of a sodium hydroxide solution is made to be lower than the outlet end of a water vapor injection pipe. Potential safety hazards such as explosions caused by the reaction of sodium with water in the prior art are avoided, a heat source having a relatively high temperature and hydrogen can be formed, and the operation cost is reduced.

Description

A system for online conversion of sodium source into heat energy and hydrogen Technical Field

[0001] The present invention relates to an energy generation system, in particular to a system for online conversion of a sodium source into thermal energy and hydrogen. Background Art

[0002] Energy is the material foundation for human social, economic, and technological development. Building an efficient, low-carbon renewable energy system is the fundamental solution to the dual crises of global energy depletion and environmental pollution. Consequently, environmentally friendly energy sources such as hydropower, wind power, photovoltaic power generation, and hydrogen energy are experiencing rapid development. However, while accelerating the development and utilization of clean energy, hydropower, wind power, and photovoltaic power generation are facing challenges in storage, transmission, and consumption.

[0003] Sodium is widely available and abundant on Earth, accounting for as much as 2.64% of the Earth's crust. Sodium has a high energy density. When metallic sodium undergoes an oxidation reaction, it releases a large amount of heat. The energy released per ton of sodium is equivalent to the calorific value of 0.4 tons of standard coal, which is twice the calorific value of hydrogen. Sodium production technology is mature. Industrially, sodium is produced by electrolysis of NaCl or NaOH, and the production rate of metallic sodium is controlled by adjusting parameters such as electrolysis conditions. Sodium storage and transportation technology is very mature, with costs equivalent to one-third of high-pressure hydrogen. In particular, sodium reacts with water to produce hydrogen and sodium hydroxide (an industrial base alkali). Using sodium as a raw material to generate hydrogen can solve challenges such as energy storage and transmission. However, sodium has strong reducing properties and reacts violently with water in the air. Existing methods for sodium-water reactions include the following:

[0004] 1. Liquid sodium (liquid sodium) is injected into a reaction vessel containing a large amount of sodium hydroxide solution to initiate a reaction between sodium and water. This reaction releases a significant amount of heat, which evaporates the water. The reaction products are sodium hydroxide solution, hydrogen, and water vapor. The hydrogen and water vapor are mixed and processed through a demister, dryer, and HEPA filter before being discharged through a chimney. The low temperature of the reaction system makes heat recovery difficult. Furthermore, the volume expansion of water as it transforms from liquid to gas poses an explosion safety hazard. Therefore, the concentration of the sodium hydroxide solution must be closely monitored and maintained at around 30% to avoid explosions caused by low alkaline solution concentration and rapid reaction speed. Consequently, this method is slow and inefficient, making it suitable only for the digestion of waste sodium metal.

[0005] 2. A reactor with an alkali liquid outlet is charged with appropriate amounts of water and kerosene, forming an oil-water two-phase system. Sodium reacts rapidly upon contact with water. The generated water vapor, due to its much lower density than kerosene, rises from the oil-water interface and no longer reacts with the sodium. The generated hydrogen passes through the kerosene layer, is cooled, and is collected for recycling. While this ensures a safe sodium-water reaction and produces the target product, hydrogen, the kerosene dissipates the heat energy generated by the reaction between the metallic sodium and water, resulting in heat loss. Furthermore, the resulting sodium hydroxide solution is contaminated with small amounts of organic impurities from the kerosene, necessitating subsequent purification of the alkali solution. This cumbersome process increases costs. Summary of the Invention

[0006] The present invention aims to solve the above-mentioned technical problems existing in the prior art and provides a system for online conversion of a sodium source into heat energy and hydrogen.

[0007] The technical solution of the present invention is: a system for online conversion of a sodium source into heat energy and hydrogen, comprising a sealed reactor, an alkali liquid discharge pipe at the bottom of the reactor, a drain valve on the alkali liquid discharge pipe, a hydrogen collection pipe at the upper end of the reactor, a pressure reducing valve on the hydrogen collection pipe, a heat exchanger, a temperature sensor, and a pressure sensor in the reactor, a liquid sodium injection pipe and a water vapor injection pipe at the bottom of the reactor, a liquid sodium injection check valve on the liquid sodium injection pipe, a water vapor injection check valve on the water vapor injection pipe, both the liquid sodium injection pipe and the water vapor injection pipe are located in the reactor, and the outlet end of the liquid sodium injection pipe is located above the outlet end of the water vapor injection pipe; the heat exchanger is arranged in an upper and lower manner, with the refrigerant inlet at the upper end and the refrigerant outlet at the lower end; a heat exchange valve is provided at the refrigerant inlet, and the temperature sensor is located at the upper end of the heat exchanger;

[0008] Follow the steps below:

[0009] Step 1. Fill the reactor with hydrogen;

[0010] Step 2. Open the heat exchange valve;

[0011] Step 3. Open the liquid sodium injection check valve and the water vapor injection check valve;

[0012] Step 4. The injected liquid sodium reacts with water vapor to produce a combustion reaction, generating hydrogen, high-temperature water vapor and sodium hydroxide; controlling the heat exchange valve, liquid sodium injection check valve and water vapor injection check valve so that the temperature of the hydrogen and high-temperature water vapor after passing through the heat exchanger is lower than 70°C, and the hydrogen is discharged from the hydrogen collection pipe through the pressure reducing valve, and the pressure reducing valve adjusts the pressure in the reactor to 0.1-10Mpa; the high-temperature water vapor condenses to the bottom of the water flow reactor after passing through the heat exchanger, and the drain valve is controlled so that the height of the sodium hydroxide solution is lower than the outlet end of the water vapor injection pipe.

[0013] The preferred technical solution is that the outlet end of the liquid sodium injection pipe and the outlet end of the water vapor injection pipe are surrounded by a combustion chamber with upper and lower openings.

[0014] The preferred technical solution is that a liquid level sensor is provided below the water vapor injection pipe.

[0015] The present invention fills the reactor with hydrogen before the reaction, placing the reactor in an oxygen-free state. After liquid sodium and water vapor are injected into the reactor, a combustion reaction occurs upon contact between the water vapor and the liquid sodium, generating hydrogen and sodium hydroxide. The water vapor that does not participate in the reaction absorbs heat and forms higher-temperature water vapor. The temperature of the mixture of hydrogen and high-temperature water vapor after passing through a heat exchanger is lower than 70°C, and the high-temperature water vapor condenses into water and flows back to the bottom of the reactor. The hydrogen is discharged from the hydrogen collection pipe through a pressure reducing valve. During the combustion reaction, the drain valve is controlled to keep the sodium hydroxide solution below the outlet end of the water vapor injection pipe. Compared with the prior art, the present invention has the following advantages:

[0016] 1. Directly using water vapor as the reaction raw material avoids the safety hazards such as explosion caused by the volume expansion of water due to the phase change of water into water vapor when heated in the existing technology;

[0017] 2. After being heated, the water vapor will further heat up and form high-temperature gas, which will exchange heat with the cold enzyme in the heat exchanger to form a higher temperature heat source, meeting the needs of industrial production for high-temperature heat sources. At the same time, the water vapor will condense to form water, which is effectively separated from the hydrogen.

[0018] 3. The product (hydrogen) that does not react with water vapor and sodium is used as the protective gas to ensure the safe combustion of the sodium-water reaction.

[0019] 4. No need to add kerosene, which can avoid the purification of sodium hydroxide solution, simple operation and reduced operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG1 is a schematic structural diagram of embodiment 1 of the present invention.

[0021] FIG2 is a schematic structural diagram of embodiment 2 of the present invention. DETAILED DESCRIPTION Example 1

[0022] A system for online conversion of a sodium source into heat energy and hydrogen of the present invention is shown in FIG1 , which comprises a closed reactor 1, a lye discharge pipe 2 at the bottom of the reactor 1, a drain valve 2-1 on the lye discharge pipe 2, a hydrogen collecting pipe 3 at the upper end of the reactor 1, a pressure reducing valve 3-1 on the hydrogen collecting pipe 3, a heat exchanger 4, a temperature sensor 5 and a pressure sensor 6 in the reactor 1, a liquid sodium injection pipe 7 and a water vapor injection pipe 8 at a certain height below the bottom of the reactor 1, and a liquid sodium injection pipe 7 on the liquid sodium injection pipe 7. The water vapor injection pipe 8 is provided with a water vapor injection check valve 8-1. The liquid sodium injection pipe 7 and the water vapor injection pipe 8 are both located within the reactor 1, and the outlet end of the liquid sodium injection pipe 7 is located above the outlet end of the water vapor injection pipe 8, so that the rising water vapor and the liquid sodium fully contact and react. The heat exchanger 4 is a single-stage or multi-stage heat exchanger arranged in an upper and lower manner, with the refrigerant inlet at the top and the refrigerant outlet at the bottom. It can be in any form, such as a serpentine or plate shape, but must ensure sufficient heat exchange with hydrogen and water vapor. A heat exchange valve 4-1 is provided at the refrigerant inlet, and a temperature sensor 5 is located at the upper end of the heat exchanger 4 to monitor the temperature of the water vapor after passing through the heat exchanger 4.

[0023] Follow the steps below:

[0024] Step 1. Fill the reactor 1 with hydrogen through the hydrogen collecting pipe 3 of the reactor 1. First, fill the reactor 1 with water, then inject hydrogen and open the drain valve 2-1. When all the water flows out, the reactor 1 is filled with hydrogen.

[0025] Step 2. Open the heat exchange valve 4-1 and inject refrigerant into the heat exchanger 4. The refrigerant can be mineral oil, low-temperature gas, etc. that can fully carry heat;

[0026] Step 3. Open the liquid sodium injection check valve 7-1 and the water vapor injection check valve 8-1, and inject liquid sodium and water vapor into the reactor 1;

[0027] Step 4. The injected liquid sodium reacts with the water vapor to produce hydrogen, high-temperature water vapor, and sodium hydroxide. The heat exchange valve 4-1, the liquid sodium injection check valve 7-1, and the water vapor injection check valve 8-1 are controlled so that the temperature of the hydrogen and high-temperature water vapor after passing through the heat exchanger 4 is lower than 70°C. The hydrogen is discharged from the hydrogen collection pipe 3 through the pressure reducing valve 3-1. The pressure reducing valve 3-1 adjusts the pressure in the reactor 1 to 0.1-10 MPa. The high-temperature water vapor condenses into water after passing through the heat exchanger 4 and flows back to the bottom of the reactor 1. At the same time, the drain valve 2-1 is controlled so that the height of the sodium hydroxide solution is lower than the outlet end of the water vapor injection pipe 8. Example 2

[0028] A system for online conversion of a sodium source into heat energy and hydrogen according to the present invention is shown in FIG2 . The basic structure and method are the same as those of Example 1. The difference from Example 1 is that the outlet end of the liquid sodium injection pipe 7 and the outlet end of the water vapor injection pipe 8 are located on one radial side of the reactor 1, and a combustion chamber 9 with upper and lower openings is provided on the periphery of the two outlet ends. The combustion chamber 9 is made of a high-temperature resistant material. In this case, the heat exchanger 4 can be tilted downward as a whole, so that the lower end is located on the other radial side of the combustion chamber 9. The provision of the combustion chamber 9 can, on the one hand, prevent the water vapor from escaping, allowing the liquid sodium and water vapor to fully react within the combustion chamber 9. On the other hand, after the water vapor condenses into water through the heat exchanger 4, it can flow back to the bottom surface of the reactor 1 along the outer surface of the heat exchanger 4, avoiding flowing into the combustion chamber 9 and reacting with the liquid sodium.

[0029] The drain valve 2-1, pressure reducing valve 3-1, liquid sodium injection check valve 7-1, and water vapor injection check valve 8-1 can all be electronic valves, controlled by a controller based on signals from a temperature sensor 5 and a pressure sensor 6. A liquid level sensor 10 connected to the controller can be provided below the water vapor injection pipe 8 to constantly monitor the level of the alkali solution and prevent the sodium hydroxide solution from exceeding the outlet end of the water vapor injection pipe 8, thereby preventing the water in the sodium hydroxide solution from reacting with the sodium.

Claims

1. A system for online conversion of a sodium source into heat energy and hydrogen, comprising a closed reactor (1), a lye discharge pipe (2) at the bottom of the reactor (1), a drain valve (2-1) on the lye discharge pipe (2), a hydrogen collection pipe (3) at the top of the reactor (1), a pressure reducing valve (3-1) on the hydrogen collection pipe (3), a heat exchanger (4), a temperature sensor (5) and a pressure sensor (6) in the reactor (1), characterized in that: A liquid sodium injection pipe (7) and a water vapor injection pipe (8) are provided below the reactor (1); a liquid sodium injection check valve (7-1) is provided on the liquid sodium injection pipe (7); a water vapor injection check valve (8-1) is provided on the water vapor injection pipe (8); the liquid sodium injection pipe (7) and the water vapor injection pipe (8) are both located inside the reactor (1); and the outlet end of the liquid sodium injection pipe (7) is located above the outlet end of the water vapor injection pipe (8); the heat exchanger (4) is a heat exchanger arranged up and down with the refrigerant inlet at the top and the refrigerant outlet at the bottom; a heat exchange valve (4-1) is provided at the refrigerant inlet; and a temperature sensor (5) is located at the upper end of the heat exchanger (4); Follow the steps below: Step 1. Filling the reactor (1) with hydrogen; Step 2. Open the heat exchange valve (4-1); Step 3. Open the liquid sodium injection check valve (7-1) and the water vapor injection check valve (8-1); Step 4. The injected liquid sodium and water vapor undergo a combustion reaction after contact, generating hydrogen, high-temperature water vapor and sodium hydroxide; the heat exchange valve (4-1), the liquid sodium injection check valve (7-1) and the water vapor injection check valve (8-1) are controlled so that the temperature of the hydrogen and the high-temperature water vapor after passing through the heat exchanger (4) is lower than 70° C., and the hydrogen is discharged from the hydrogen collection pipe (3) through the pressure reducing valve (3-1), and the pressure reducing valve (3-1) adjusts the pressure in the reactor (1) to 0.1-10 MPa; the high-temperature water vapor condenses to the bottom of the water flow reactor (1) after passing through the heat exchanger (4), and the drain valve (2-1) is controlled so that the height of the sodium hydroxide solution is lower than the outlet end of the water vapor injection pipe (8).

2. The system for online conversion of sodium source into heat energy and hydrogen according to claim 1, characterized in that: A combustion chamber (9) with upper and lower openings is provided on the periphery of the outlet end of the liquid sodium injection pipe (7) and the outlet end of the water vapor injection pipe (8).

3. The system for online conversion of sodium source into heat energy and hydrogen according to claim 1, characterized in that: A liquid level sensor (10) is provided below the water vapor injection pipe (8).

Images