An AC / DC controllable modular power supply system for green ammonia synthesis

Abstract

The present invention discloses an AC / DC controllable modular power supply system for green ammonia synthesis, which belongs to the field of electric control technology and relates to the power distribution and control of an electric heater in a green ammonia device. Specifically, 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 by different control modules. The system comprises a power supply unit and a control unit. The control unit comprises 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 to maintain the temperature in the ammonia tower stable when the green ammonia device is in operation or insulation state. The power supply unit is composed of multiple standard AC / DC power modules, so that the electric heater is in a high-efficiency operation state even under low load.

Description

Technical Field

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

[0002] Green ammonia synthesis plants utilize electricity generated by photovoltaic, hydropower, and wind power (referred to as green electricity) for production and operation. Due to the fluctuating nature of green electricity, green ammonia plants often operate at low loads or shut down for insulation. Furthermore, during normal operation, the reaction heat generated by the plant compensates for temperature fluctuations and even achieves self-balancing. Therefore, green ammonia electric heaters must often operate at low loads.

[0003] Compared to traditional ammonia synthesis plants, green ammonia plants are generally smaller in scale and utilize smaller ammonia synthesis towers, which limits the space within the towers. When installing electric heaters within the towers, to ensure mechanical strength and insulation distance from the tower walls, three-phase heaters are generally avoided. Single-circuit heaters with larger diameters and shorter lengths are used. Single-circuit heaters include single-phase and DC heaters. Because single-phase heaters are prone to phase imbalance, DC heaters are often used in green ammonia plants under the same circumstances.

[0004] Conventionally, the matching DC power supply is selected according to the rated power of the electric heater. When the green ammonia electric heater is running at low load, the corresponding DC power supply is also in the low load rate range. However, the efficiency of the DC power supply is very low when running at low load rate (for example, some DC power supplies produced by Huawei do not record the efficiency of the load rate below 10%, see Figure 4 Since the DC power supply selected for the rated power of the electric heater is usually custom-made, low-load operation is prone to power failures, which can cause difficulties for the green ammonia plant. To address this issue, some green ammonia plants have added additional equipment outside the ammonia tower to install a three-phase electric heater.

[0005] In combination with the above, the methods and shortcomings of the electric heaters used in existing small-scale green ammonia plants are summarized as follows:

[0006] Select an electric heater suitable for installation within the ammonia tower, powered by a non-standard DC power supply. Disadvantages: Frequent low-load operation of the electric heater leads to low power efficiency or failure, increasing power consumption and failure rate. Select a three-phase electric heater installed outside the ammonia tower. Disadvantages: Additional equipment increases the green ammonia plant's footprint and equipment investment. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide an AC / DC controllable modular power supply system for green ammonia synthesis in response to the shortcomings of the background technology. The power distribution of the electric heater is completed through multiple AC / DC power supply modules, and the control of different stages and states of the electric heater is realized through different control modules.

[0008] The present invention adopts the following technical solutions to solve the above technical problems:

[0009] An AC / DC controllable modular power supply system for green ammonia synthesis, comprising a power supply unit and a control unit;

[0010] The control unit includes a remote control module, a control execution module, and a temperature control module. The power supply unit includes multiple AC and DC power supply modules. The control execution module and the AC and DC power supply modules 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 when the green ammonia device is in operation or insulation state.

[0011] The power supply unit is composed of multiple standard AC and DC power modules, which enables the electric heater to operate in a high-efficiency state even at low load.

[0012] As a further preferred embodiment of the AC / DC controllable modular power supply system for green ammonia synthesis of the present invention, the remote control module comprises a comparator (C1-Cn), a transistor (T1-Tn), a relay (K1-Kn), a resistor chain (R1-Rn+1), an input voltage Vd, an input voltage Vref, and an input voltage Vi;

[0013] The input voltage Vd is used to power the relays (K1-Kn), which turns on the corresponding transistors (T1-Tn). The input voltage Vref is used as the reference voltage for the comparator. Specifically, the resistor chain R1-Rn generates a comparator voltage divider (Vref1-Vrefn) at the input of each comparator (C1-Cn) and serves as the comparison benchmark. The input voltage Vi is the remote control signal input voltage.

[0014] When the remote control module receives an external command, the input voltage Vi changes and is compared with the comparator voltage divider Vrefn. When the input voltage Vi is greater than the comparator voltage divider Vrefn, the comparators (C1-Cn) output a high level; otherwise, they output a low level. When the comparator voltage divider Vref2 is less than the input voltage Vi and less than the comparator voltage divider Vref3, the comparators (C1-C2) output a high level, transistors (T1-T2) conduct, comparators (C3-Cn) are low, and transistors (T3-Tn) are off. The coils of the relays (K1-K2) are energized, and the corresponding contacts of the relays (K1-K2) close. This energizes the contactor coils (KM1-KM2) in the control execution module, closing the contactor switches (KM1-KM2) and supplying power to the AC / DC power modules (P1-P2). The contactor switches (KM3-KMn) are open, and power is not supplied to the AC / DC modules (P3-Pn). Through this process, the remote control module controls the temperature rise or temperature drop rate during the start or stop process of the green ammonia device within the allowable value.

[0015] As a further preferred embodiment of the AC / DC controllable modular power supply system for green ammonia synthesis according to 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 controlling and executing the remote module and the temperature module. When the green ammonia unit transitions from operation to normal shutdown, control by the remote module is required. If the temperature module is in control at this time, the control switch SA2 is disconnected, automatically switching to the remote control module.

[0016] As a further preferred embodiment of the present invention for an AC / DC controllable modular power supply system for green ammonia synthesis, by increasing communication or electrical connection between the control execution module and each power module (P1 to Pn) in the power supply unit, a continuous load rate adjustment function for each AC / DC power module is implemented, which significantly increases the control accuracy of the temperature in the ammonia tower of the green ammonia plant and reduces the temperature fluctuation range.

[0017] As a further preferred embodiment of the AC / DC controllable modular power supply system for green ammonia synthesis according to the present invention, the temperature control module is configured to transmit a real-time temperature detection signal within the ammonia synthesis tower via a temperature sensor installed within the tower. When the green ammonia unit is in normal operation or insulation, if the real-time detected temperature is lower than or higher than the set values ​​Ts1 to Tsn of each level within the temperature controller, the corresponding contactors (KM1 to KMn) within the control execution module are energized or de-energized, thereby controlling the corresponding contactor switches (KM1 to KMn) within the power supply unit to close or open. The temperature within the tower is maintained stable during normal operation or insulation of the green ammonia unit through an automatic temperature control process.

[0018] As a further preferred embodiment of the present invention, a controllable AC / DC modular power supply system for green ammonia synthesis comprises a power supply unit comprising a plurality of AC / DC power modules (P1-Pn), contactor switches (KM1-KMn), and a three-phase AC power supply (L1-L3). By closing or opening the contactor switches (KM1-KMn), the AC / DC power modules (P1-Pn) are sequentially switched on or off, thereby providing DC power to the electric heater at different operating loads ranging from 0% to 100%.

[0019] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0020] The present invention proposes an AC / DC controllable modular power supply system for green ammonia synthesis, which includes a power supply unit and a control unit. 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 by different control modules. 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 when the green ammonia device is in operation or insulation state. The power supply unit is composed of multiple standard AC / DC power modules, so that the electric heater can operate in a high-efficiency state even under low load. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a structural schematic diagram of an AC / DC controllable modular power supply system for green ammonia synthesis according to the present invention;

[0022] Figure 2 is a schematic diagram of a power supply unit of the present invention;

[0023] Figure 3 It is a schematic diagram of the control unit of the present invention;

[0024] Figure 4 This is a diagram showing that some DC power supplies produced by Huawei do not record the operating efficiency at a load rate below 10%. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings:

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 work are within the scope of protection of the present invention. The present invention is described in detail below based on the drawings and preferred embodiments. The purpose and effect of the present invention will become more clear. 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.

[0027] like Figure 1 As shown, the present invention comprises two units: a power supply unit and a control unit. The power supply unit is composed of multiple AC and DC power 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. The detailed functions of each module are described as follows:

[0028] AC / DC power modules: Figure 2 The main structure of the power supply unit is shown in the figure. The main components are multiple AC and DC power modules (P1 to Pn). The main selection principles of the AC and DC power modules are: (1) three-phase AC power input; (2) the minimum load power of the electric heater is within the high-efficiency operating range of the AC and DC power modules. There are many standard AC and DC power modules on the market that meet the requirements of this invention, which will not be described here. Figure 2 In the circuit, the external input is the three-phase AC power supply L1~L3. By closing or opening the contactor switches KM1~KMn, the AC and DC power modules P1~Pn are switched on or off in sequence, completing the DC power supply of the electric heater with different operating loads of 0~100%.

[0029] Temperature control module: through the temperature sensor installed in the ammonia synthesis tower, such as Figure 2 As shown, the real-time detection signal of the temperature in the tower is transmitted to the temperature module as shown in Figure 3 As shown in the figure, when the green ammonia unit is operating normally or holding, if the real-time detected temperature falls below or rises above the set values ​​Ts1 to Tsn in the temperature controller, the corresponding contactor coils KM1 to KMn in the control execution module will be energized or de-energized, thereby controlling the corresponding contactor switches KM1 to KMn in the power supply unit to close or open. Through this automatic temperature control process, the temperature control module maintains a stable temperature within the tower during normal operation or holding.

[0030] Remote control module: Figure 3The diagram shows the main internal structure of the remote control module. The remote control module is mainly composed of comparators C1~Cn, transistors T1~Tn, relays K1~Kn, resistor chains R1~Rn+1 and other components. Among them, the module contains three different input voltages, namely input voltage Vd, input voltage Vref and input voltage Vi, among which: Vd is used to power the relay coils K1~Kn (after the corresponding transistors T1~Tn are turned on); Vref is used as the reference voltage of the comparator, specifically through the resistor chain R1~Rn to generate a voltage divider Vref1~Vrefn at the input end of each comparator C1~Cn, and used as a comparison benchmark; Vi is the remote control signal input voltage. When the remote control module receives an external instruction, the Vi voltage changes and is compared with the comparator voltage divider Vrefn. When Vi is greater than Vrefn, the comparator C1~Cn outputs a high level, otherwise it outputs a low level. For example, in Figure 3 When Vref2 < Vi < Vref3, C1-C2 output a high level, transistors T1-T2 conduct, C3-Cn are low, and transistors T3-Tn are blocked. Relays K1-K2 are energized, closing their corresponding contacts K1-K2. This energizes contactor coils KM1-KM2 in the control execution module, closing contactor switches KM1-KM2 and ultimately energizing AC / DC power modules P1-P2. Meanwhile, KM3-KMn are open, and AC / DC modules P3-Pn are not powered. Through this process, the remote control module controls the temperature rise or fall rate during the start-up or shutdown of the green ammonia plant to within the permitted value.

[0031] Control execution module: Figure 3 The diagram illustrates the main internal structure of the control execution module, which primarily consists of contactors KM1 through KMn and KS, and control switches SA1 and SA2. The execution module is electrically connected to the power supply unit (communication with the power modules can be added to adjust the load factor of each power module within the highest efficiency range). It is responsible for controlling and executing the remote and temperature modules. When the green ammonia unit transitions from operation to normal shutdown, control must be taken from the remote module. If the temperature module is in control at this time, disconnecting control switch SA2 automatically switches to the remote control module.

[0032] The present invention controls 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; maintains the temperature in the ammonia tower stable when the green ammonia device is in operation or insulation state; and adopts multiple standard AC and DC power supply modules to form a power supply unit, so that the electric heater can operate in a high-efficiency state even under low load.

[0033] Example 1: A 2000 TPA (tons per annum) green ammonia plant requires a 100 kW electric heater installed in the ammonia synthesis tower. During normal operation, the tower temperature is approximately 450°C, never exceeding 510°C. During insulation operation, the tower temperature is set at 200°C. To ensure equipment safety, the temperature ramp rate during startup and shutdown must not exceed 50°C / hour. The AC / DC power supply system is connected to the green ammonia control system for control, and the control system's AO (analog output) channel meets 1-5V output requirements.

[0034] The parameters of the selected AC and DC power modules are shown in Table 1:

[0035] Table 1

[0036]

[0037] The parameters of the remote control module and temperature control module are shown in Table 2 and Table 3:

[0038] Table 2

[0039]

[0040] Table 3

[0041]

[0042] The control system's human-machine interface (HMI) issues a 0-100% output command, and the corresponding AO channel outputs a 1-5V analog voltage signal to the Vi interface. Based on Vref and the resistance values ​​of resistor chain R1 and R2-R51, we know that Vref1 = 1V; Vref2 = 1.08V; Vref3 = 1.16V, and so on, all the way to Vref50 = 4.92V.

[0043] When HMI output is 0%, Vi=1V;

[0044] When 0%<HMI<2%, 1V<Vi<1.08V, C1 outputs high level, T1 is turned on, the corresponding relay K1 coil is energized, thereby controlling the contactor switch KM1 to close, the power module P1 is powered on, and P2~P50 are not powered;

[0045] When 2%<HMI<4%, 1.08V<Vi<1.16V, C1~C2 output high level, T1~T2 are turned on, the corresponding relay K1~K2 coils are energized, thereby controlling the contactor switches KM1~KM2 to close, the power modules P1~P2 are powered, and P3~P50 are not powered;

[0046] The process continues in this way until HMI>98%, Vi>4.92V, C1~C50 output high level, and power modules P1~P50 are all put into power supply.

[0047] To ensure the heating rate does not exceed 50°C / h, it is necessary to control the time interval between HMI commands to increase by 2%. For example, if the temperature rise of the electric heater is linearly related to the power supply, the time interval between HMI commands to increase by 2% can be greater than 12 minutes. In actual operation, the control system command time interval should be modified based on the electric heater's heating curve.

[0048] When the green ammonia unit is operating normally, the AC and DC power supply systems operate in the following modes:

[0049] When the green ammonia unit is operating normally, the temperature control module controls the power supply, which can be switched automatically or manually:

[0050] a. Automatic switching. When the temperature inside the tower is greater than 510°C (or the TSH setting is lower than 510°C), the TSH switch (normally open) is closed, and the relay KS coil is energized, causing the KS switch to switch from 1 and 3 closed to 1 and 2 closed; at the same time, all power modules are cut off from power supply, and the temperature control module controls the power supply.

[0051] b. Manual switching. When the operator observes that the temperature inside the tower is greater than 450°C, the SA1 switch is manually closed, and the relay KS coil is energized, causing the KS switch to switch from 1 and 3 closed to 1 and 2 closed; at the same time, all power modules are cut off from power supply, and the temperature control module is used to control the power input;

[0052] When the temperature inside the tower is lower than 450℃, the TS1 switch is triggered to close and the power module P1 starts to supply power;

[0053] When the temperature inside the tower is lower than 440°C, the switches TS1 and TS2 are triggered to close, and the power modules P1 and P2 start supplying power.

[0054] Similarly, other power modules are powered by temperature control. Generally, the lower the green ammonia unit's operating load, the more power modules are required. If the green ammonia unit's operating load approaches 100%, the temperature can usually be self-balanced, meaning the reaction heat keeps the temperature at or above 450°C, and no power supply is required.

[0055] When the green ammonia unit is in insulation state, the AC and DC power supply system operates in the following ways:

[0056] When the green ammonia device needs to be kept warm, it is also required to switch to the temperature control module mode.

[0057] Manually close the SA1 switch, and the relay KS coil is energized, causing the KS switch to change from 1 and 3 closed to 1 and 2 closed; at the same time, all power modules cut off power supply, and the temperature module controls power input.

[0058] When the temperature inside the tower is lower than 200℃, the TS1 switch is triggered to close and the power module P1 starts to supply power;

[0059] When the temperature inside the tower is lower than 190°C, the switches TS1 and TS2 are triggered to close, and the power modules P1 and P2 start supplying power.

[0060] Similarly, other power modules are powered by temperature control to maintain a stable temperature of 200°C inside the tower.

[0061] When the green ammonia unit stops normally, the AC and DC power supply system is put into use in the following way: Generally speaking, the normal shutdown of the green ammonia unit starts from normal operation. At this time, the SA2 (normally closed) switch is manually opened, and the relay KS coil loses power, causing the KS switch to change from 1 and 2 closed to 1 and 3 closed, and the power supply is switched from the temperature module to the remote module control.

[0062] Similar to the startup of a green ammonia plant, the cooling rate can be controlled by reducing the HMI command interval by 2%. For example, if the temperature rise of the electric heater is linearly related to the power supply, reducing the HMI command interval by 2% by more than 12 minutes is sufficient. In actual operation, the control system command interval should be modified based on the electric heater's temperature rise curve.

[0063] Example 2: R100030G1 and R100040G2 produced by Huawei Technologies Co., Ltd. also meet the requirements of the AC / DC power supply module of the present invention. When using the above modules, a communication protocol conversion configuration is added to the control execution module so that the remote control module or the temperature control module can effectively control the load rate of each AC / DC power supply module within the efficiency curve of 10% to 100%. Figure 4 ) to meet the temperature ramp rate requirements of the green ammonia plant. It's important to note that adding continuous load factor adjustment to each AC / DC power module significantly improves temperature control accuracy within the green ammonia plant's ammonia tower and reduces temperature fluctuations. Aside from the continuous load factor adjustment feature, the rest of the commissioning and operation is similar to Example 1 and will not be further elaborated here.

[0064] Those skilled in the art will understand that the above descriptions are merely preferred embodiments of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will still 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, etc. made within the spirit and principles of the invention shall be included within the scope of protection of the invention. All technical features in this embodiment may be freely combined according to actual needs.

[0065] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is 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 can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An AC / DC controllable modular power supply system for green ammonia synthesis, characterized by: Contains a power supply unit and a control unit; The control unit includes a remote control module, a control execution module, and a temperature control module. The power supply unit includes multiple AC and DC power supply modules. The control execution module and the AC and DC power supply modules 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 when the green ammonia device is in operation or insulation state. The power supply unit is composed of multiple standard AC and DC power modules, which enables the electric heater to operate at high efficiency even at low load; 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; The input voltage Vd is used to power relays K1 through Kn, which is when the corresponding transistors T1 through Tn are turned on. The input voltage Vref is used as the reference voltage for the comparators. Specifically, the resistor chain R1 through Rn+1 generates the comparator voltages Vref1 through Vrefn at the input of each comparator C1 through Cn, which serve as the comparison benchmark. The input voltage Vi is the remote control signal input voltage. When the remote control module receives an external command, the input voltage Vi changes and is compared with the comparator voltage divider Vrefn. When the input voltage Vi is greater than the comparator voltage divider Vrefn, comparators C1-Cn output a high level; otherwise, they output a low level. When the comparator voltage divider Vref2 is less than the input voltage Vi and less than the comparator voltage divider Vref3, comparators C1-C2 output a high level, transistors T1-T2 conduct, comparators C3-Cn output a low level, and transistors T3-Tn are blocked. The coils of relays K1-K2 are energized, and the corresponding contacts of relays K1-K2 close, energizing contactors KM1-KM2 in the control execution module. Contactors KM1-KM2 in the AC / DC power supply module close, and AC / DC power supply modules P1-P2 are powered. Contactors KM3-KMn are in the open state, and AC / DC modules P3-Pn are not powered. This is used to control the temperature rise or cool down rate during the start-up or shutdown process of the green ammonia plant to within the allowable value.

2. The AC / DC controllable modular power supply system for green ammonia synthesis according to claim 1, characterized in that: The control execution module includes contactors 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 device switches from operation to normal stop, it needs to be controlled by the remote module. If it is controlled by the temperature module at this time, the control switch SA2 will be disconnected and it will automatically switch to the remote control module.

3. The AC / DC controllable modular power supply system for green ammonia synthesis according to claim 1, characterized in that: The temperature control module is used to transmit a real-time detection signal of the temperature inside the ammonia synthesis tower through a temperature sensor installed in the ammonia synthesis tower. When the green ammonia unit is in normal operation or insulation state, if the real-time detected temperature is lower than or higher than the set values ​​Ts1~Tsn of each level in the temperature controller, the corresponding contactors KM1~KMn in the control execution module will be energized or de-energized, thereby controlling the corresponding contactors KM1~KMn in the power supply unit to close or open. The temperature in the tower is maintained stable during normal operation or insulation of the green ammonia unit through the automatic temperature control process.

4. The AC / DC controllable modular power supply system for green ammonia synthesis according to claim 1, characterized in that: The power supply unit includes multiple AC / DC power modules P1~Pn, contactors KM1~KMn and three-phase AC power supplies L1~L3. By closing or opening the contactors KM1~KMn, the AC / DC power modules P1~Pn are switched on or off in sequence to complete the DC power supply of the electric heater with different operating loads of 0~100%.

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