AC / DC controllable modular power supply system applied to green ammonia synthesis

Abstract

The invention discloses an alternating current and direct current controllable modular power supply system applied to green ammonia synthesis, belongs to the technical field of electric control, and relates to power distribution and control of an electric heater of a green ammonia device. Specifically, power distribution of the electric heater is completed through a plurality of AC / DC power supply modules, and control of different stages and states of the electric heater is realized through different control modules. The device comprises a power unit and a control unit. Wherein the control unit comprises a remote control module, a control execution module and a temperature control module, and is used for controlling the temperature rising and falling speed in the ammonia tower to meet the requirement in the starting or stopping process of the green ammonia device and maintaining the temperature in the ammonia tower to be stable when the green ammonia device runs or is in a heat preservation state; a plurality of standard AC / DC power supply modules are adopted to form a power supply unit, so that the electric heater is also in a high-efficiency operation state under low load.

Description

Technical Field

[0001] The present invention belongs to the field of power distribution and control of electric heaters for green ammonia plants, and particularly relates to an AC / DC controllable modular power supply system applied to green ammonia synthesis. Background Art

[0002] The green ammonia synthesis plant uses electric energy (referred to as green power) generated by photovoltaic, hydraulic, wind power, etc. for production operation. Due to the characteristics of large fluctuations in green power, the green ammonia plant often operates at light load or shuts down for heat preservation. In addition, when the plant is operating normally, the generated reaction heat energy compensates for the temperature or even achieves temperature self-balance. Therefore, the green ammonia electric heater needs to operate at a low load state frequently.

[0003] Compared with traditional ammonia synthesis plants, green ammonia plants are generally smaller in scale and use small-sized ammonia synthesis towers, which results in limited space inside the ammonia tower. When installing an electric heater inside the tower, in order to ensure the mechanical strength of the electric heater and the insulation distance from the tower wall, generally, three-phase electric heaters are avoided and single-loop electric heaters with a larger diameter and shorter length are used. The single-loop electric heater includes single-phase electric heaters and DC electric heaters. Because single-phase electric heaters are prone to inter-phase imbalance, DC electric heaters are often used in green ammonia plants under the same conditions.

[0004] Conventionally, a supporting DC power supply is selected according to the rated power of the electric heater. When the green ammonia electric heater operates at a low load, the corresponding DC power supply is also in the low load rate range, and the DC power supply has very low efficiency when operating in the low load rate range (for example, some DC power supplies produced by Huawei do not record the operating efficiency at a load rate below 10%, see Figure 4 ). Since the DC power supply corresponding to the rated power of the electric heater is usually non-standard customized, power supply failures are more likely to occur during low-load operation, causing the green ammonia plant to fall into trouble. To solve this problem, some green ammonia plants also add additional equipment outside the ammonia tower for installing three-phase electric heaters.

[0005] Combining the above, the methods and disadvantages of the electric heaters used in existing small-scale green ammonia plants are summarized as follows: Select an electric heater suitable for installation inside the ammonia tower and supply power with 1 set of non-standard DC power supply. Disadvantages: Due to the frequent low-load operation of the electric heater, the power supply efficiency is low or a failure occurs, increasing the power consumption and failure rate of the plant. Select a three-phase electric heater installed outside the ammonia tower. Disadvantages: Additional equipment is added, resulting in an increase in the floor area and equipment investment of the green ammonia plant. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a controllable AC / DC modular power supply system for green ammonia synthesis in view of the deficiencies of the background technology. The power distribution of the electric heater is completed by multiple AC / DC power modules, and the control of different stages and states of the electric heater is realized through different control modules.

[0007] The present invention adopts the following technical solutions to solve the above technical problems: A controllable AC / DC modular power supply system for green ammonia synthesis, comprising a power supply unit and a control unit; Among them, the control unit includes a remote control module, a control execution module, and a temperature control module. The power supply unit includes multiple AC / DC power modules. The control execution module and the AC / DC power modules control the temperature rise and fall speed in the ammonia tower to meet the requirements during the startup or shutdown process of the green ammonia device, and maintain the temperature in the ammonia tower stable during the operation or heat preservation state of the green ammonia device; The power supply unit is composed of multiple standard AC / DC power modules to form the power supply unit, so that the electric heater can also operate at high efficiency under low load.

[0008] As a further preferred solution of the controllable AC / DC modular power supply system for green ammonia synthesis of the present invention, the remote control module includes comparators (C1~Cn), transistors (T1~Tn), relays (K1~Kn), resistor chains (R1~Rn+1), input voltage Vd, input voltage Vref and input voltage Vi; Wherein: the input voltage Vd is used to supply power to the relays (K1~Kn), that is, after the corresponding transistors (T1~Tn) are turned on; the input voltage Vref is the reference voltage of the comparator. Specifically, the comparator voltage division (Vref1~Vrefn) is generated at the input end of each comparator (C1~Cn) through the resistor chains R1~Rn and used as the comparison reference. The input voltage Vi is the input voltage of the remote control signal; When the remote control module receives an external instruction, the input voltage Vi changes and is compared with the comparator voltage division Vrefn. When the input voltage Vi is greater than the comparator voltage division Vrefn, the comparators (C1~Cn) output a high level, otherwise a low level; when the comparator voltage division Vref2 < input voltage Vi < comparator voltage division Vref3, the comparators (C1~C2) output a high level, the transistors (T1~T2) conduct, the comparators (C3~Cn) are at a low level, and the transistors (T3~Tn) do not conduct; the coils of the relays (K1~K2) are energized, and the corresponding contacts of the relays (K1~K2) close, controlling the coils of the contactors (KM1~KM2) in the control execution module to be energized, and the contactor switches (KM1~KM2) close, and the AC / DC power supply modules (P1~P2) are put into power supply; and the contactor switches (KM3~KMn) are in the open state, and the AC / DC modules (P3~Pn) are not put into power supply. Through this process, the remote control module controls the heating or cooling rate during the startup or shutdown process of the green ammonia device within the allowable value.

[0009] As a further preferred solution of the AC / DC controllable modular power supply system applied to green ammonia synthesis of the present invention, the control execution module includes contactors (KM1~KMn), a relay KS, and control switches (SA1~SA2); the execution module is electrically connected to the power supply unit and is responsible for the control execution of the remote module and the temperature module; when the green ammonia device is transferred from operation to normal shutdown, it needs to be controlled by the remote module. If it is controlled by the temperature module at this time, the control switch SA2 is disconnected, and it will automatically switch to the remote control module.

[0010] As a further preferred solution of the AC / DC controllable modular power supply system applied to green ammonia synthesis of the present invention, by increasing the communication or electrical connection between the control execution module and each power supply module (P1~Pn) in the power supply unit, the function of continuously adjusting the load rate of each AC / DC power supply module is realized, which will significantly increase the control accuracy of the temperature in the ammonia tower of the green ammonia device and narrow the temperature fluctuation range.

[0011] As a further preferred solution of the AC / DC controllable modular power supply system applied to green ammonia synthesis of the present invention, the temperature control module is used to transmit the real-time detection signal of the temperature in the tower through the temperature sensors installed in the ammonia synthesis tower; when the green ammonia device is in normal operation or heat preservation state, when the real-time detected temperature is lower or higher than the set values Ts1~Tsn at all levels in the temperature controller, the corresponding contactors (KM1~KMn) in the control execution module will be energized or de-energized, thereby controlling the corresponding contactor switches (KM1~KMn) in the power supply unit to close or open; the stability of the temperature in the tower during the normal operation or heat preservation of the green ammonia device is maintained through the temperature automatic control process.

[0012] As a further preferred solution of an AC-DC controllable modular power supply system applied to green ammonia synthesis in the present invention, the power supply unit includes a plurality of AC-DC power modules (P1~Pn), contactor switches (KM1~KMn), and three-phase AC power supplies (L1~L3). By closing or opening the contactor switches (KM1~KMn), the AC-DC power modules (P1~Pn) are sequentially connected or disconnected to complete the DC power supply for different operating loads of the electric heater from 0 to 100%.

[0013] With the above technical solutions, the present invention has the following technical effects compared with the prior art: The present invention provides an AC-DC controllable modular power supply system applied to green ammonia synthesis, which includes a power supply unit and a control unit; the power distribution of the electric heater is completed by a plurality of AC-DC power modules, and the control of different stages and states of the electric heater is realized through different control modules; among them, the control unit includes a remote control module, a control execution module, and a temperature control module, which are used to control the temperature rise and fall speed in the ammonia tower to meet the requirements during the start-up or shutdown process of the green ammonia device, and maintain the temperature in the ammonia tower stable during the operation or heat preservation state of the green ammonia device; the power supply unit is composed of a plurality of standard AC-DC power modules, so that the electric heater can also operate at a high efficiency under low load. Description of the Drawings

[0014] Figure 1 is the structural schematic diagram of an AC-DC controllable modular power supply system applied to green ammonia synthesis in the present invention; Figure 2 is the schematic diagram of the power supply unit of the present invention; Figure 3 is the schematic diagram of the control unit of the present invention; Figure 4 is the schematic diagram of the operating efficiency of some DC power supplies produced by Huawei not recording below 10% load rate. Detailed Embodiments

[0015] The technical solutions of the present invention will be further described in detail below with reference to the drawings: The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. The present invention will be described in detail below according to the drawings and preferred embodiments, and the purpose and effect of the present invention will become more obvious. It should be understood that the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0016] As Figure 1As shown in the figure, the present invention includes two units, namely a power supply unit and a control unit: the power supply unit is composed of multiple AC-DC power supply modules with the same parameters and technical specifications; the control unit is composed of a remote control module, a control execution module, and a temperature control module. Among them, the detailed function descriptions of each module are as follows: AC-DC power supply module: Figure 2 Schematically shows the main structure inside the power supply unit, and the main components are multiple AC-DC power supply modules (P1~Pn). Among them, the main selection principles of the AC-DC power supply module are: (1) Three-phase AC power input; (2) The minimum load power of the electric heater is within the high-efficiency operation range of the AC-DC power supply module. There are many standard AC-DC power supply modules on the market that meet the requirements of the present invention, so they will not be elaborated here. In Figure 2 it, the external input is the three-phase AC power supply of L1~L3. By closing or opening the contactor switches KM1~KMn, the AC-DC power supply modules P1~Pn are sequentially put into or cut off, completing the DC power supply for different operating loads of 0~100% of the electric heater.

[0017] Temperature control module: Through the temperature sensors installed in the ammonia synthesis tower, as Figure 2 shown, it transmits the real-time detection signal of the tower temperature to the temperature module as Figure 3 shown. When the green ammonia device is in normal operation or heat preservation state, when the real-time detected temperature is lower or higher than the set values Ts1~Tsn at all levels in the temperature controller, the corresponding contactor coils KM1~KMn in the control execution module will be energized or de-energized, thereby controlling the closing or opening of the corresponding contactor switches KM1~KMn in the power supply unit. Through this automatic temperature control process, the temperature control module will maintain the stability of the tower temperature when the green ammonia device is in normal operation or heat preservation.

[0018] Remote control module: Figure 3 Schematically shows the main structure inside the remote control module. The remote control module is mainly composed of components such as comparators C1~Cn, transistors T1~Tn, relays K1~Kn, and resistor chains R1~Rn+1. Among them, the module includes three different input voltages, namely input voltage Vd, input voltage Vref, and input voltage Vi, where: Vd is used to supply power to the relay coils K1~Kn (after the corresponding transistors T1~Tn are turned on); Vref is the reference voltage for the comparator. Specifically, voltage divisions Vref1~Vrefn are generated at the input terminals of each comparator C1~Cn through the resistor chain R1~Rn and used as the comparison reference; Vi is the input voltage of the remote control signal. When the remote control module receives an external instruction, the voltage of Vi changes and is compared with the voltage division Vrefn of the comparator. When Vi is greater than Vrefn, the comparators C1~Cn output a high level, otherwise they output a low level. For example, in Figure 3When Vref2 < Vi < Vref3, C1 to C2 output a high level, transistors T1 to T2 conduct, C3 to Cn are at a low level, and transistors T3 to Tn do not conduct; the coils of relays K1 to K2 are energized, and the corresponding contacts K1 to K2 close, controlling the coils of contactors KM1 to KM2 in the control execution module to be energized, and the contactor switches KM1 to KM2 are closed, finally the AC / DC power supply modules P1 to P2 are put into power supply; at the same time, KM3 to KMn are in the open state, and the AC / DC modules P3 to Pn are not put into power supply. Through this process, the remote control module controls the heating or cooling rate during the startup or shutdown process of the green ammonia plant within the allowable value.

[0019] Control execution module: Figure 3 Schematically shows the main internal structure of the control execution module, mainly composed of contactors KM1 to KMn and KS, control switches SA1 to SA2, etc. The execution module is electrically connected to the power supply unit (the communication connection function with the power module can be added to adjust the load rate of each power module within the high-efficiency range), and is responsible for the control execution of the remote module and the temperature module. Among them, when the green ammonia plant is transferred from operation to normal shutdown, it needs to be controlled by the remote module. If it is controlled by the temperature module at this time, the control switch SA2 is disconnected, and it will automatically switch to the remote control module.

[0020] In the startup or shutdown process of the green ammonia plant of the present invention, the temperature rise and fall rate in the ammonia tower is controlled to meet the requirements; when the green ammonia plant is in operation or in the heat preservation state, the temperature in the ammonia tower is maintained stable; a power supply unit is composed of multiple standard AC / DC power supply modules, so that the electric heater is also in a high-efficiency operation state under low load.

[0021] Example 1 In a 2000 TPA (tons per year) green ammonia plant, it is necessary to install a 100 KW electric heater in the ammonia synthesis tower. During normal operation, the temperature in the tower is about 450 °C and does not exceed 510 °C. During heat preservation operation, the set temperature in the tower is 200 °C. To ensure the safety of the equipment, the temperature rise and fall rate during the startup and shutdown of the plant does not exceed 50 °C / h. Among them, the AC / DC power supply system is connected to the green ammonia control system for control, and the AO (analog output) channel of the control system meets the 1 to 5 V output requirements.

[0022] The parameters of the selected AC / DC power supply module are shown in Table 1: Table 1

[0023] The parameters of the remote control module and the temperature control module are shown in Tables 2 and 3: Table 2

[0024] Table 3

[0025] The human-machine interface (HMI) of the control system gives an output command of 0 to 100%, and the corresponding AO channel outputs an analog voltage signal of 1 to 5V to the Vi interface. According to the values of Vref, the resistance chain R1, and R2 to R51, it can be known that Vref1 = 1V; Vref2 = 1.08V; Vref3 = 1.16V, until Vref50 = 4.92V.

[0026] When the HMI outputs 0%, Vi = 1V; When 0% < HMI < 2%, 1V < Vi < 1.08V, C1 outputs a high level, T1 conducts, and the corresponding relay K1 coil is energized, thereby controlling the contactor switch KM1 to close, and the power supply module P1 is put into power supply, while P2 to P50 are not powered; When 2% < HMI < 4%, 1.08V < Vi < 1.16V, C1 to C2 output high levels, T1 to T2 conduct, and the corresponding relay K1 to K2 coils are energized, thereby controlling the contactor switches KM1 to KM2 to close, and the power supply modules P1 to P2 are put into power supply, while P3 to P50 are not powered; And so on, until HMI > 98%, Vi > 4.92V, C1 to C50 output high levels, and the power supply modules P1 to P50 are all put into power supply.

[0027] To ensure that the heating rate is not higher than 50°C / h, it is necessary to control the time interval for the HMI command to increase by 2%. For example, when the temperature rise of the electric heater and the power of the power supply are in a linear relationship, the time interval for the HMI command to increase by 2% being greater than 12 minutes is sufficient. During actual operation, the command time interval of the control system needs to be modified in combination with the heating curve of the electric heater.

[0028] When the green ammonia plant is operating normally, the operation mode of the AC / DC power supply system: When the green ammonia plant is operating normally, it is switched to the temperature control module to control the power supply input, which can be switched automatically or manually: a. Automatic switching. When the temperature inside the tower > 510°C (or the TSH setting is lower than 510°C), at this time, the TSH switch (normally open) closes, and the relay KS coil is energized, causing the KS switch to change from being closed at 1 and 3 to being closed at 1 and 2; at the same time, all power supply modules cut off the power supply and switch to the temperature control module to control the power supply input; b. Manual switching. When the operator observes that the temperature inside the tower > 450°C, manually close the SA1 switch, and the relay KS coil is energized, causing the KS switch to change from being closed at 1 and 3 to being closed at 1 and 2; at the same time, all power supply modules cut off the power supply and switch to the temperature control module to control the power supply input; When the temperature inside the tower is lower than 450°C, trigger the TS1 switch to close, and the power supply module P1 is put into power supply; When the temperature inside the tower is lower than 440°C, the TS1~TS2 switches are triggered to close, and the power modules P1~P2 are put into power supply; And so on, other power modules are put into power supply controlled by temperature. Generally, the lower the operating load of the green ammonia plant, the more power modules need to be put into operation. If the operating load of the green ammonia plant is close to 100%, temperature self-balance can usually be achieved, that is, the reaction heat causes the temperature not to be lower than 450°C, and no power supply is required.

[0029] When the green ammonia plant is in the heat preservation state, the operation mode of the AC / DC power supply system: When the green ammonia plant needs to be heat-preserved, it is also required to switch to the temperature control module mode.

[0030] Manually close the SA1 switch, the relay KS coil is energized, and the KS switch changes from being closed at 1 and 3 to being closed at 1 and 2; at the same time, all power modules are cut off from power supply, and the power supply is switched to be controlled by the temperature module.

[0031] When the temperature inside the tower is lower than 200°C, the TS1 switch is triggered to close, and the power module P1 is put into power supply; When the temperature inside the tower is lower than 190°C, the TS1~TS2 switches are triggered to close, and the power modules P1~P2 are put into power supply; And so on, other power modules are put into power supply controlled by temperature to maintain the temperature inside the tower at 200°C stably.

[0032] When the green ammonia plant stops normally, the power supply input mode of the AC / DC power supply system: Generally speaking, the normal stop of the green ammonia plant starts from normal operation. At this time, manually operate the SA2 (normally closed) switch to open, the relay KS coil loses power, and the KS switch changes from being closed at 1 and 2 to being closed at 1 and 3, and the power supply is switched from the temperature module to the remote module control.

[0033] Similar to when the green ammonia plant starts up, controlling the HMI command to reduce the time interval by 2% can achieve the control of the cooling rate. For example, when the temperature rise of the electric heater and the power are linearly related, it is sufficient that the HMI command reduces the time interval by 2% and is greater than 12 minutes. During actual operation, the control system command time interval needs to be modified in combination with the heating curve of the electric heater.

[0034] Example 2: R100030G1 and R100040G2 produced by Huawei Technologies Co., Ltd. also meet the requirements of the AC / DC power module of the present invention. When using the above modules, add communication protocol conversion configuration in the control execution module, so that the remote control module or the temperature control module can effectively load the rate within the efficiency curve of 10%~100% for each AC / DC power module ( Figure 4Adjust continuously to meet the requirements of the temperature rise and fall speed of the green ammonia plant. It should be noted that adding the continuous adjustment function of the load rate of each AC / DC power module will significantly improve the temperature control accuracy in the ammonia tower of the green ammonia plant and reduce the temperature fluctuation range. Except for the continuous adjustment function of the load rate, other input and operation methods are similar to those in Example 1 and will not be elaborated here.

[0035] Those of ordinary skill in the art can understand that the above are only preferred examples of the invention and are not used to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, for those skilled in the art, they can still modify the technical solutions described in the foregoing examples or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, etc. made within the spirit and principle of the invention shall be included within the protection scope of the invention. All technical features in this embodiment can be freely combined according to actual needs.

[0036] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A controllable AC / DC modular power supply system for green ammonia synthesis, characterized in that: It includes a power supply unit and a control unit; Among them, the control unit includes a remote control module, a control execution module, and a temperature control module. The power supply unit includes multiple AC / DC power supply modules. During the startup or shutdown process of the green ammonia plant, the control execution module and the AC / DC power supply modules control the temperature rise and fall rate in the ammonia tower to meet the requirements. During the operation or heat preservation state of the green ammonia plant, they maintain the temperature stability in the ammonia tower; The power supply unit is composed of multiple standard AC / DC power supply modules, enabling the electric heater to operate at high efficiency even under low load.

2. The AC / DC controllable modular power supply system applied to green ammonia synthesis according to claim 1, wherein: The remote control module includes comparators (C1~Cn), transistors (T1~Tn), relays (K1~Kn), resistor chains (R1~Rn+1), input voltage Vd, input voltage Vref, and input voltage Vi; Among them: The input voltage Vd is used to supply power to the relays (K1~Kn), that is, after the corresponding transistors (T1~Tn) are turned on; the input voltage Vref is the reference voltage of the comparator. Specifically, the comparator voltage division (Vref1~Vrefn) is generated at the input end of each comparator (C1~Cn) through the resistor chain R1~Rn+1 and used as the comparison reference. The input voltage Vi is the input voltage of the remote control signal; When the remote control module receives an external instruction, the voltage of the input voltage Vi changes and is compared with the comparator voltage division Vrefn. When the input voltage Vi is greater than the comparator voltage division Vrefn, the comparators (C1~Cn) output a high level, otherwise they output a low level; when the comparator voltage division Vref2 < input voltage Vi < comparator voltage division Vref3, the comparators (C1~C2) output a high level, the transistors (T1~T2) are turned on, the comparators (C3~Cn) are at a low level, and the transistors (T3~Tn) are not turned on; the coils of the relays (K1~K2) are energized, and the corresponding contacts of the relays (K1~K2) are closed, the contactors (KM1~KM2) in the control execution module are energized, and the contactors (KM1~KM2) are switched on, and the AC / DC power supply modules (P1~P2) are put into power supply; and the contactors (KM3~KMn) are in the off state, and the AC / DC modules (P3~Pn) are not put into power supply; it is used to control the heating or cooling rate during the startup or shutdown process of the green ammonia plant within the allowable value.

3. A controllable AC / DC modular power supply system for green ammonia synthesis according to claim 1, characterized in that: The control execution module includes contactor switches (KM1~KM2), relay KS, and control switches (SA1~SA2); the execution module is electrically connected to the power supply unit and is responsible for the control execution of the remote module and the temperature module; when the green ammonia plant is switched from operation to normal shutdown, it needs to be controlled by the remote module. If it is controlled by the temperature module at this time, the control switch SA2 is disconnected, and it will automatically switch to the remote control module.

4. A controllable AC / DC modular power supply system for green ammonia synthesis according to claim 1, characterized in that: The temperature control module is used to transmit the real-time detection signal of the temperature inside the tower through the temperature sensor installed in the ammonia synthesis tower; when the green ammonia device is in normal operation or heat preservation state, when the real-time detected temperature is lower or higher than the set values Ts1~Tsn at all levels in the temperature controller, the corresponding contactors (KM1~KMn) in the control execution module will be energized or de-energized, so as to control the closing or opening of the corresponding contactors (KM1~KMn) in the power supply unit; the stability of the temperature inside the tower during the normal operation or heat preservation of the green ammonia device is maintained through the temperature automatic control process.

5. A controllable AC / DC modular power supply system for green ammonia synthesis according to claim 1, characterized in that: The power supply unit includes multiple AC / DC power supply modules (P1~Pn), contactors (KM1~KMn) and three-phase AC power supply (L1~L3). By closing or opening the contactors (KM1~KMn), the AC / DC power supply modules (P1~Pn) are sequentially put into or cut off to complete the DC power supply for different operating loads of the electric heater from 0 to 100%.

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