Energy-saving and consumption-reducing method for coal tar hydrogenation compressor

Abstract

The invention belongs to the technical field of coal tar hydrogenation, in particular to an energy-saving and consumption-reducing method for a coal tar hydrogenation compressor, which is characterized in that a desalting water tank is additionally arranged in a compressor cooling system of a coal tar hydrogenation device, and liquid nitrogen is used as a cold source of the desalting water tank to precool or deeply cool desalting water entering a compressor cooler. Cooling water (demineralized water) far lower than the environment temperature is provided, the exhaust temperature of each stage of the compressor is greatly reduced, according to the thermodynamic principle, gas is compressed at the low temperature, the compression work of the gas is remarkably reduced (close to isothermal compression), and therefore the power consumption (or steam consumption) of a compressor driving motor (or a steam turbine) is directly reduced, and the energy consumption is reduced. The energy-saving effect is particularly outstanding when the environment temperature is high, demineralized water is used as a cooling medium, the scaling problem caused by water hardness of traditional circulating cooling water is thoroughly avoided, the high heat exchange efficiency of the cooler is maintained for a long time, and energy consumption and maintenance cost rise caused by scaling are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of coal tar hydrogenation, and specifically to a method for energy conservation and consumption reduction of a coal tar hydrogenation compressor. Background Technique

[0002] In the coal tar hydrogenation process, circulating hydrogen compressors, fresh hydrogen compressors, etc. are core equipment with huge power consumption, which is one of the main components of the device energy consumption. During the operation of the compressor, a large amount of heat is generated when the gas is compressed, and an efficient cooling system (usually an inter-stage cooler and a post-cooler) is required to cool the compressed high-temperature gas to the temperature required by the process to ensure the compressor efficiency and the stability of the subsequent process. The traditional cooling system mainly relies on circulating cooling water or air coolers: Circulating water cooling requires a large amount of electric energy to drive the cooling water pump and the cooling tower fan. The cooling efficiency is greatly affected by the ambient temperature, and the efficiency drops significantly in summer. The cooling water is easy to scale, reducing the heat transfer efficiency, increasing the maintenance cost and energy consumption. The cooling water system itself has problems such as evaporation loss and sewage discharge of water resources; Air cooler: It has a large floor area and high investment, and is also significantly affected by the ambient temperature. The cooling effect is poor in high-temperature weather, which may cause the exhaust gas temperature of the compressor to be too high, reducing the efficiency or even triggering interlock shutdown.

[0003] According to the Chinese invention patent application with the publication number CN119638010A, a flue gas carbon capture amine liquid purification system using carbon dioxide purge is disclosed, which relates to the technical field of amine liquid purification. The prior art: includes a resin desalination module, and the resin desalination module is respectively connected to a purification pipeline, a gas transmission pipeline, a liquid transmission pipeline and an alkali liquid tank; valves are provided on the purification pipeline, the gas transmission pipeline and the liquid transmission pipeline; the purification pipeline is connected to a filtration subsystem; the filtration subsystem is connected to an amine liquid pipeline; the amine liquid of the carbon capture system is input into the filtration subsystem through the amine liquid pipeline; the gas transmission pipeline is connected to the gas outlet of the carbon capture system, and the gas outlet is used for discharging the CO<subgt;2< / subgt; product gas of the carbon capture system; a compressor is also connected between the gas outlet and the gas transmission pipeline; the liquid transmission pipeline is respectively connected to a circulation water tank and a demineralized water tank.

[0004] The Chinese invention patent application with publication number CN119778646A discloses an air compression storage system for power generation, which relates to the field of air compression storage technology. The existing technology: includes an air filter device, which is connected to a compressor through a universal pipeline, and the compressor is connected to a cooler. The other side of the cooler is connected to an expansion liquefier through a universal pipeline, and the other side of the expansion liquefier is connected to a liquefied air storage device through a universal pipeline. The outlet of the liquefied air storage device is connected to a gasification converter through a universal pipeline, and the other side of the gasification converter is an air pump. The other side of the air pump is connected to a power generation device through a universal pipeline. In summary, the outer layer of the universal pipeline is provided with a vacuum layer, and a valve is provided in the middle of each universal pipeline. The valve, the compressor, the cooler, the expansion liquefier, the gasification converter, and the air pump are all controlled by a central controller.

[0005] The desalted water used in the compressor in the above-mentioned patent solution cannot be effectively recycled, and some technologies use a cooler to cool the compressor, which has a relatively high production cost. In addition, the compressor system only mentions adding a circulating water tank for desalted water, but does not mention the cooling method of the circulating water in the circulating water tank, which cannot ensure the long-term stable operation of the compressor. For this reason, we propose a method for energy saving and consumption reduction of coal tar hydrogenation compressors. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention provides a method for energy saving and consumption reduction of a coal tar hydrogenation compressor, which solves the problem that the desalted water used in the compressor cannot be effectively recycled, and some technologies use a cooler to cool the compressor, which has a relatively high production cost. Moreover, the compressor system only mentions adding a circulating water tank for desalted water, but does not mention the cooling method of the circulating water in the circulating water tank, which cannot ensure the long-term stable operation of the compressor.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for energy saving and consumption reduction of a coal tar hydrogenation compressor, wherein a desalted water tank is newly provided in the compressor cooling system of the coal tar hydrogenation unit, and liquid nitrogen is used as a cold source for the desalted water tank to pre-cool or deeply cool the desalted water entering the compressor cooler, specifically comprising the following steps:

[0008] Step 1: Set up a desalted water tank: In the existing compressor cooling water system (or a new system), add one or more desalted water tanks, which are used to store desalted water as the cooling medium for the compressor cooler.

[0009] Step 2: Establish a liquid nitrogen cooling system: Utilize the liquid nitrogen raw material of the compressor protection gas, modify the inlet pipe of the liquid nitrogen tank to the newly added desalted water tank, cool the circulating water, and send the outlet liquid nitrogen to the inlet of the liquid nitrogen vaporizer. Send the heated liquid nitrogen to the vaporizer for vaporization to improve the vaporization efficiency.

[0010] Step three: Use liquid nitrogen to cool the desalted water: Control the injection flow of liquid nitrogen based on the cooling requirements of the compressor and the supply of liquid nitrogen. The liquid nitrogen absorbs the heat of the desalted water in the heat exchange coil and then vaporizes to produce low-temperature nitrogen.

[0011] Step 4: Supply low-temperature desalted water to the compressor cooler: The low-temperature desalted water cooled by liquid nitrogen is pumped from the desalted water tank to the coolers at each stage of the compressor (interstage cooler, aftercooler). The low-temperature desalted water exchanges heat with the compressed high-temperature process gas in the cooler, efficiently removing the compression heat.

[0012] Step five, treatment of low-temperature nitrogen. The low-temperature nitrogen generated in step three is collected. Part of it can be recycled as shielding gas for the compressor to reduce the consumption of additional shielding gas. The remaining low-temperature nitrogen can be transported to other process links with low-temperature requirements.

[0013] As a preferred technical solution of the present invention, the desalted water tank in step one is provided with a heat exchange coil. The heat exchange coil is evenly distributed inside the desalted water tank to ensure sufficient contact area with the desalted water, thereby achieving efficient heat exchange. The material of this coil is a metal with good thermal conductivity, which can quickly transfer the coldness of liquid nitrogen to the desalted water. At the same time, the diameter and length of the coil are carefully designed to ensure that the liquid nitrogen flows smoothly therein and meet the requirements of cooling the desalted water to the target temperature. In order to further improve the heat exchange efficiency, a special heat sink structure is also provided on the outside of the coil to increase the surface area of ​​heat exchange. In addition, high-precision flow and temperature sensors are installed at the inlet and outlet of the coil to monitor and control the injection amount of liquid nitrogen and the cooling effect of the desalted water in real time, ensuring the stability and reliability of the entire cooling process.

[0014] As a preferred technical solution of the present invention, the compressor cooler in step one includes but is not limited to an interstage cooler and an aftercooler.

[0015] As a preferred technical solution of the present invention, the compressor cooling demand in step three can be flexibly adjusted according to factors such as the target desalted water temperature, ambient temperature and compressor load. By monitoring these parameters in real time, the supply amount and flow rate of liquid nitrogen are dynamically adjusted using an intelligent control system to accurately meet the cooling needs of the compressor under different working conditions. For example, when the ambient temperature is high or the compressor load increases, the injection amount of liquid nitrogen is appropriately increased to ensure that the desalted water can be maintained within a suitable temperature range, thereby providing a stable and efficient cooling effect for the compressor. At the same time, combined with the data fed back by the flow and temperature sensors, the cooling process is finely controlled to avoid unnecessary waste of liquid nitrogen and further improve the effect of energy saving and consumption reduction.

[0016] As a preferred technical solution of the present invention, in step three, the temperature of the desalted water in the desalted water tank is cooled to 5-10°C by utilizing the strong heat absorption capacity (large latent heat of vaporization) of liquid nitrogen.

[0017] As a preferred technical solution of the present invention, the high-temperature process gas in step 4 includes hydrogen or recycled hydrogen.

[0018] As a preferred technical solution of the present invention, the desalted water after heating in step 4 can be treated in the following two ways: a) returned to the desalted water tank and re-cooled by liquid nitrogen to form a closed cycle; b) partially discharged (or used for other low-grade heat users) and replenished with new desalted water.

[0019] As a preferred technical solution of the present invention, the temperature of the low-temperature nitrogen gas generated by vaporizing the liquid nitrogen in step 5 is -10°C to -50°C.

[0020] As a preferred technical solution of the present invention, the low-temperature nitrogen gas generated by vaporizing the liquid nitrogen in step five is mainly used for protecting the sealing gas system.

[0021] Compared with the prior art, the present invention provides a method for energy saving and consumption reduction of a coal tar hydrogenation compressor, which has the following beneficial effects:

[0022] 1. This method for energy saving and consumption reduction of coal tar hydrogenation compressors significantly reduces the exhaust temperature of each level of the compressor by providing cooling water (demineralized water) at a temperature far below the ambient temperature. According to the principles of thermodynamics, gas is compressed at a lower temperature, and its compression work is significantly reduced (close to isothermal compression), thereby directly reducing the power consumption (or steam consumption) of the compressor drive motor (or steam turbine). The energy saving effect is particularly prominent when the ambient temperature is high.

[0023] 2. This method of energy saving and consumption reduction for coal tar hydrogenation compressors uses desalted water as the cooling medium, completely avoiding the scaling problem caused by water hardness in traditional circulating cooling water. This maintains the high heat exchange efficiency of the cooler over a long period of time, and avoids the additional energy consumption and equipment maintenance costs caused by scaling. When a closed cycle is used, the desalted water has basically no evaporation loss or sewage loss, which greatly saves fresh water consumption and reduces water treatment costs. The closed cycle reduces or even eliminates the operating load of the cooling tower fan and cooling water pump (the flow rate may decrease due to the increase in temperature difference), indirectly saving the power consumption of these auxiliary equipment.

[0024] 3. This method of energy conservation and consumption reduction for coal tar hydrogenation compressors uses a controllable liquid nitrogen cooling source to regulate the cooling water temperature, which is essentially unaffected by ambient temperature fluctuations. This ensures that the compressor can operate efficiently and stably even in hot seasons, avoiding the risk of load reduction or shutdown due to insufficient cooling. The lower operating temperature and stable cooling effect help extend the service life of the compressor body and cooler. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the process structure of the present invention. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0027] Example

[0028] See also Figure 1 In this embodiment, a method for energy saving and consumption reduction of a coal tar hydrogenation compressor is provided, characterized in that a desalted water tank is newly provided in the compressor cooling system of the coal tar hydrogenation unit, and liquid nitrogen is used as a cold source for the desalted water tank to pre-cool or deeply cool the desalted water entering the compressor cooler, specifically comprising the following steps:

[0029] Step 1: Install a desalted water tank: Add one or more desalted water tanks to the existing compressor cooling water system (or a newly constructed system). These tanks store desalted water, which serves as the cooling medium for the compressor coolers (including but not limited to interstage coolers and aftercoolers). Heat exchange coils are evenly distributed within the tank to ensure sufficient contact area with the desalted water, enabling efficient heat exchange. These coils are constructed of a metal with excellent thermal conductivity, enabling rapid transfer of cooling energy from liquid nitrogen to the desalted water. The coil diameter and length are carefully designed to ensure smooth flow of liquid nitrogen while cooling the desalted water to the target temperature. To further improve heat exchange efficiency, a special heat sink structure is installed on the outside of the coils to increase the heat exchange surface area. Furthermore, high-precision flow and temperature sensors are installed at the coil inlet and outlet to monitor and control the injection rate of liquid nitrogen and the cooling effect of the desalted water in real time, ensuring the stability and reliability of the entire cooling process.

[0030] Step 2: Establish a liquid nitrogen cooling system: Utilize the liquid nitrogen raw material of the compressor protection gas, modify the inlet pipe of the liquid nitrogen tank to the newly added desalted water tank, cool the circulating water, and send the outlet liquid nitrogen to the inlet of the liquid nitrogen vaporizer. Send the heated liquid nitrogen to the vaporizer for vaporization to improve the vaporization efficiency.

[0031] Step 3: Use liquid nitrogen to cool the desalted water: According to the cooling demand of the compressor and the supply of liquid nitrogen, the injection flow rate of liquid nitrogen is controlled. The liquid nitrogen absorbs the heat of the desalted water in the heat exchange coil and then vaporizes to produce low-temperature nitrogen gas. The strong heat absorption capacity of liquid nitrogen (large latent heat of vaporization) cools the desalted water temperature in the desalted water tank to 5-10°C. The cooling demand of the compressor can be flexibly adjusted according to factors such as the target desalted water temperature, ambient temperature and compressor load. By monitoring these parameters in real time, the supply and flow rate of liquid nitrogen are dynamically adjusted using an intelligent control system to accurately meet the cooling needs of the compressor under different operating conditions. For example, when the ambient temperature is high or the compressor load increases, the injection rate of liquid nitrogen is appropriately increased to ensure that the desalted water can be maintained within the appropriate temperature range, thereby providing a stable and efficient cooling effect for the compressor. At the same time, combined with the data feedback from the flow and temperature sensors, the cooling process is finely controlled to avoid unnecessary liquid nitrogen waste and further improve the effect of energy saving and consumption reduction.

[0032] Step 4: Supply low-temperature desalted water to the compressor cooler: The low-temperature desalted water cooled by liquid nitrogen is pumped from the desalted water tank to the coolers at each stage of the compressor (interstage cooler, aftercooler). The low-temperature desalted water exchanges heat with the compressed high-temperature process gas (including hydrogen or circulating hydrogen) in the cooler, efficiently removing the heat of compression. The desalted water that has absorbed heat and heated up (after temperature rise) can be selected to: a) return to the desalted water tank and be cooled by liquid nitrogen again to form a closed cycle; b) partially discharged (or used for other low-grade heat users) and replenished with new desalted water.

[0033] Step 5: Treatment of cryogenic nitrogen. The cryogenic nitrogen (-10°C to -50°C) produced in step 3 is collected and some of it can be recycled as shielding gas for the compressor to reduce the consumption of additional shielding gas. The remaining cryogenic nitrogen can be transported to other process links with low-temperature requirements.

[0034] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for energy saving and consumption reduction of a coal tar hydrogenation compressor, characterized in that: In the compressor cooling system of the coal tar hydrogenation unit, a desalted water tank is newly provided, and liquid nitrogen is used as the cold source of the desalted water tank to pre-cool or deeply cool the desalted water entering the compressor cooler. Specifically, the following steps are included: Step 1: Set up a desalted water tank: In the existing compressor cooling water system (or a new system), add one or more desalted water tanks, which are used to store desalted water as the cooling medium for the compressor cooler. Step 2: Establish a liquid nitrogen cooling system: Utilize the liquid nitrogen raw material of the compressor protection gas, modify the inlet pipe of the liquid nitrogen tank to the newly added desalted water tank, cool the circulating water, and send the outlet liquid nitrogen to the inlet of the liquid nitrogen vaporizer. Send the heated liquid nitrogen to the vaporizer for vaporization to improve the vaporization efficiency. Step three: Use liquid nitrogen to cool the desalted water: Control the injection flow of liquid nitrogen based on the cooling requirements of the compressor and the supply of liquid nitrogen. The liquid nitrogen absorbs the heat of the desalted water in the heat exchange coil and then vaporizes to produce low-temperature nitrogen. Step 4: Supply low-temperature desalted water to the compressor cooler: The low-temperature desalted water cooled by liquid nitrogen is pumped from the desalted water tank to the coolers at each stage of the compressor (interstage cooler, aftercooler). The low-temperature desalted water exchanges heat with the compressed high-temperature process gas in the cooler, efficiently removing the compression heat. Step five, treatment of low-temperature nitrogen. The low-temperature nitrogen generated in step three is collected. Part of it can be recycled as shielding gas for the compressor to reduce the consumption of additional shielding gas. The remaining low-temperature nitrogen can be transported to other process links with low-temperature requirements.

2. The method for energy saving and consumption reduction of a coal tar hydrogenation compressor according to claim 1, characterized in that: The desalted water tank in step one is provided with a heat exchange coil. The heat exchange coil is evenly distributed inside the desalted water tank to ensure sufficient contact area with the desalted water, thereby achieving efficient heat exchange. The material of this coil is a metal with good thermal conductivity, which can quickly transfer the coldness of liquid nitrogen to the desalted water. At the same time, the diameter and length of the coil are carefully designed to ensure that the liquid nitrogen flows smoothly therein and meet the requirements of cooling the desalted water to the target temperature. In order to further improve the heat exchange efficiency, a special heat sink structure is also provided on the outside of the coil to increase the surface area of ​​heat exchange. In addition, high-precision flow and temperature sensors are installed at the inlet and outlet of the coil to monitor and control the injection amount of liquid nitrogen and the cooling effect of the desalted water in real time, thereby ensuring the stability and reliability of the entire cooling process.

3. The method for energy saving and consumption reduction of a coal tar hydrogenation compressor according to claim 1, characterized in that: The compressor cooler in step 1 includes but is not limited to an interstage cooler and an aftercooler.

4. The method for energy saving and consumption reduction of a coal tar hydrogenation compressor according to claim 1, characterized in that: The compressor cooling demand in step three can be flexibly adjusted according to factors such as the target desalted water temperature, ambient temperature and compressor load. By monitoring these parameters in real time, the supply amount and flow rate of liquid nitrogen can be dynamically adjusted using an intelligent control system to accurately meet the cooling needs of the compressor under different working conditions. For example, when the ambient temperature is high or the compressor load increases, the injection amount of liquid nitrogen is appropriately increased to ensure that the desalted water can be maintained within the appropriate temperature range, thereby providing a stable and efficient cooling effect for the compressor. At the same time, combined with the data fed back by the flow and temperature sensors, the cooling process can be finely controlled to avoid unnecessary waste of liquid nitrogen and further improve the effect of energy saving and consumption reduction.

5. The method for energy saving and consumption reduction of a coal tar hydrogenation compressor according to claim 1, characterized in that: In step 3, the desalted water in the desalted water tank is cooled to 5-10°C by the strong heat absorption capacity of liquid nitrogen (large latent heat of vaporization).

6. The method for energy saving and consumption reduction of a coal tar hydrogenation compressor according to claim 1, characterized in that: The high-temperature process gas in step 4 includes hydrogen or recycled hydrogen.

7. The method for energy saving and consumption reduction of a coal tar hydrogenation compressor according to claim 1, characterized in that: The desalted water after heating in step 4 can be treated in the following two ways: a) returned to the desalted water tank and re-cooled by liquid nitrogen to form a closed cycle; b) partially discharged (or used for other low-grade heat users) and replenished with new desalted water.

8. The method for energy saving and consumption reduction of a coal tar hydrogenation compressor according to claim 1, characterized in that: The temperature of the low-temperature nitrogen gas generated by vaporizing the liquid nitrogen in step 5 is -10°C to -50°C.

9. The method for energy saving and consumption reduction of a coal tar hydrogenation compressor according to claim 1, characterized in that: The low-temperature nitrogen generated by vaporizing the liquid nitrogen in step 5 is mainly used for protecting the sealing gas system.

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