Energy-saving intermediate medium gasifier system and control method thereof

Abstract

The present invention discloses an energy-saving intermediate medium vaporizer system and a control method thereof, belonging to the technical field of energy-saving vaporizers. The system solves the problem in the prior art that conventional intermediate medium vaporizer systems are difficult to achieve energy-saving effects in operating conditions without an external heat source. The system provides a first temperature sensor between the seawater inlet and the vaporizer inlet, a second temperature sensor above the vaporizer exhaust port, a third temperature sensor on the inner wall of the heat exchange tube of the thermostat, and a fourth temperature sensor on the inner wall of the heat exchange tube of the evaporator. The system collects the output temperatures of the first, second, third, and fourth temperature sensors through a control system, compares them with a preset temperature, freezing temperature, and natural gas temperature, and adjusts the operating speed of the seawater pump. The system achieves state switching between normal operation and energy-saving operation, avoids rupture of the heat exchange tube due to excessively low temperature, and can be applied to liquefied natural gas receiving stations.

Description

Technical Field

[0001] The present invention relates to a gasifier system and a control method thereof, and in particular to an energy-saving intermediate medium gasifier system and a control method thereof, belonging to the technical field of energy-saving gasifiers. Background Art

[0002] Natural gas is currently recognized worldwide as a green and environmentally friendly energy source. However, natural gas is usually in liquid form and needs to be gasified before use. At present, my country's existing large-scale gasifiers mainly include open-frame gasifiers, submerged combustion gasifiers and intermediate medium gasifiers. Among them, intermediate medium gasifiers mostly use propane as the intermediate medium and seawater as the heat source. The intermediate medium is heated by the primary heat source, and the intermediate medium steam is then used to heat the liquefied natural gas, which can greatly improve the impact of freezing. Although the initial investment is large, the operating cost is low, and the requirements for heat source seawater are relatively low. It is suitable for use in sea areas with relatively turbid seawater, that is, sea areas with suspended sediment greater than 80 mg / l.

[0003] During the use of the intermediate medium vaporizer (IFV), the minimum design temperature of seawater as a heat source is generally 6.85°C, and the temperature difference between the inlet and outlet is less than 5°C. Due to the small heat transfer temperature difference, the seawater flow rate demand is very large. When the gasification capacity is 210 tons per hour, the seawater flow rate demand reaches about 9,000 tons per hour. The power of the seawater pump is 1500KW, resulting in high operating costs. With the rapid development of my country's natural gas industry, energy conservation and environmental protection have become the focus of my country's natural gas development. How to achieve energy conservation and environmental protection while the vaporizer is gasifying has become the main direction of industry development.

[0004] In the prior art, the patent document with the publication (announcement) number CN114111173A discloses a new vaporizer system and its use method suitable for different latitudes and inland areas, including an IFV preheating water circulation to preheat the inlet water of the intermediate medium vaporizer. When the inlet water reaches the working temperature of the intermediate medium vaporizer, the intermediate medium vaporizer heats the inlet water into cooling water. When the cooling water temperature reaches the cooling temperature, the cooling water after heat exchange flows out of the intermediate medium vaporizer and enters the indoor activity area refrigeration water circulation and the cold storage refrigeration water circulation for exchange. Heat, and then enter the IFV preheated water circulation. When the cooling water temperature does not reach the cooling temperature, the cooling water after heat exchange flows out of the intermediate medium vaporizer and enters the enhanced refrigeration water circulation for cooling. When the cooling water reaches the cooling temperature, it enters the indoor activity area refrigeration water circulation and the cold storage refrigeration water circulation for heat exchange, and then enters the IFV preheated water circulation; it expands the use scope and regional use restrictions of the intermediate medium vaporizer, and realizes energy saving by utilizing waste heat under conditions with continuous waste heat source, but it is not suitable for achieving energy saving effects under conditions without external heat source.

[0005] In summary, there is a need for an energy-saving intermediate medium gasifier system. Summary of the Invention

[0006] A brief overview of the present invention is provided below to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to identify key or important aspects of the present invention, nor is it intended to limit the scope of the present invention. Its purpose is simply to present certain concepts in a simplified form as a prelude to the more detailed description discussed later.

[0007] In view of this, in order to solve the problem in the prior art that the conventional intermediate medium gasifier system is difficult to achieve energy saving effect under the working condition without external heat source, the present invention provides an energy-saving intermediate medium gasifier system and a control method thereof.

[0008] Technical solution 1 is as follows: an energy-saving intermediate medium vaporizer system, comprising a seawater inlet, a first temperature sensor, a vaporizer, a second temperature sensor, a third temperature sensor, a control system, a fourth temperature sensor, a seawater outlet, and a seawater pump;

[0009] The vaporizer includes an evaporator and a thermostat;

[0010] The seawater pump is connected to the seawater inlet, and the seawater inlet is connected to the vaporizer inlet;

[0011] The first temperature sensor is arranged between the seawater inlet and the vaporizer inlet;

[0012] The second temperature sensor is arranged above the exhaust port of the gasifier;

[0013] The third temperature sensor is arranged on the inner wall of the heat exchange tube of the thermostat;

[0014] The fourth temperature sensor is arranged on the inner wall of the heat exchange tube of the evaporator;

[0015] The seawater outlet is connected to the vaporizer outlet;

[0016] The control system is connected to the first temperature sensor, the second temperature sensor, the third temperature sensor, the fourth temperature sensor and the seawater pump respectively. The control system is used to collect the output temperatures of the first temperature sensor, the second temperature sensor, the third temperature sensor and the fourth temperature sensor, and control the start, stop and operating speed of the seawater pump.

[0017] Technical Solution 2 is as follows: A control method for an energy-saving intermediate medium gasifier system according to Technical Solution 1 includes the following steps:

[0018] S1. Design the intermediate medium vaporizer according to the heat exchange ratio formula and calculate the normal seawater flow rate as the seawater flow rate during normal operation;

[0019] S2. Set the preset seawater inlet temperature as the minimum temperature for energy-saving operation based on the operating conditions, and calculate the energy-saving seawater flow rate as the maximum seawater flow rate during energy-saving operation using the heat exchange ratio formula;

[0020] S3. The control system compares the real-time inlet temperature collected by the first temperature sensor with the preset temperature, and switches the system operation state by adjusting the operating speed of the seawater pump according to the first temperature step judgment condition;

[0021] Specifically:

[0022] The first temperature step judgment condition is: when the real-time inlet temperature collected by the first temperature sensor is less than the preset temperature, the energy-saving intermediate medium vaporizer system remains in normal operation; when the real-time inlet temperature collected by the first temperature sensor is greater than the preset temperature, the control system will reduce the operating speed of the seawater pump to reduce the seawater flow rate, and the energy-saving intermediate medium vaporizer system will switch to energy-saving operation;

[0023] S4. Set the freezing temperature of the inner wall of the evaporator and thermostat heat exchange tubes. The control system compares the real-time evaporator heat exchange tube inner wall temperature collected by the fourth temperature sensor and the real-time thermostat heat exchange tube inner wall temperature collected by the third temperature sensor with the freezing temperature, and adjusts the operating speed of the seawater pump according to the second temperature step judgment condition to ensure system operation;

[0024] Specifically:

[0025] The second temperature step judgment condition is as follows: when the real-time evaporator heat exchange tube inner wall temperature collected by the fourth temperature sensor and the real-time thermostat heat exchange tube inner wall temperature collected by the third temperature sensor are both greater than the freezing temperature, the energy-saving intermediate medium vaporizer system remains in the current operating state; when either the real-time evaporator heat exchange tube inner wall temperature collected by the fourth temperature sensor or the real-time thermostat heat exchange tube inner wall temperature collected by the third temperature sensor is less than the freezing temperature, the control system controls the seawater pump to increase the operating speed and seawater flow rate until the real-time evaporator heat exchange tube inner wall temperature collected by the fourth temperature sensor and the real-time thermostat heat exchange tube inner wall temperature collected by the third temperature sensor are both greater than the freezing temperature;

[0026] S5. The natural gas temperature at the vaporizer exhaust port is set based on user needs. The control system compares the real-time vaporizer exhaust port temperature collected by the second temperature sensor with the natural gas temperature and adjusts the operating speed of the seawater pump according to the third temperature step judgment condition to ensure system operation;

[0027] Specifically:

[0028] The judgment condition for the third temperature step is: when the real-time vaporizer exhaust port temperature collected by the second temperature sensor is greater than the natural gas temperature, the energy-saving intermediate medium vaporizer system remains in the current operating state; when the real-time vaporizer exhaust port temperature collected by the second temperature sensor is less than the natural gas temperature, the control system controls the seawater pump to increase the operating speed and increase the seawater flow rate until the real-time vaporizer exhaust port temperature collected by the second temperature sensor is greater than the natural gas temperature.

[0029] Furthermore, in S1, the heat exchange ratio formula is expressed as:

[0030] Q=c·m'·Δt

[0031] Where Q is the heat transfer capacity in W, c is the specific heat capacity in J / (kg·℃), m' is the medium flow rate in kg / s, and Δt is the temperature difference between the inlet and outlet of the medium in ℃.

[0032] The normal seawater flow rate m'1 is calculated based on the heat exchange ratio formula and the operating data as the seawater flow rate in the normal operating state.

[0033] Furthermore, in S2, a preset temperature of the seawater inlet is set according to the operating condition data, i.e., the minimum temperature for energy-saving operation, and an energy-saving seawater flow rate m'2 corresponding to the minimum temperature for energy-saving operation is calculated according to the heat exchange ratio formula as the maximum seawater flow rate in the energy-saving operation state.

[0034] The beneficial effects of the present invention are as follows: the present invention arranges a first temperature sensor between the seawater inlet and the vaporizer inlet, arranges a second temperature sensor above the exhaust port of the vaporizer, arranges a third temperature sensor on the inner wall of the heat exchange tube of the thermostat, and arranges a fourth temperature sensor on the inner wall of the heat exchange tube of the evaporator. The control system collects the output temperatures of the first temperature sensor, the second temperature sensor, the third temperature sensor, and the fourth temperature sensor, and compares them with the set preset temperature, the freezing temperature, and the natural gas temperature, and adjusts the operating speed of the seawater pump to enable the system to switch between normal operating state and energy-saving state, while avoiding the rupture of the heat exchange tube due to excessively low temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0036] Figure 1 This is a schematic diagram of the structure of an energy-saving intermediate medium gasifier system;

[0037] Figure 2 This is a schematic diagram of an embodiment of an energy-saving intermediate medium gasifier system;

[0038] Figure 3 The figure is a flow chart of a control method for an energy-saving intermediate medium gasifier system.

[0039] Figure numerals: 1. Seawater inlet; 2. First temperature sensor; 3. Vaporizer; 4. Second temperature sensor; 5. Third temperature sensor; 6. Control system; 7. Fourth temperature sensor; 8. Seawater outlet; 9. Seawater pump; E1. Evaporator; E3. Thermostat. DETAILED DESCRIPTION

[0040] To make the technical solutions and advantages of the embodiments of the present invention more clearly understood, exemplary embodiments of the present invention are further described in detail below with reference to the accompanying drawings. It should be noted that the embodiments described are only a portion of the embodiments of the present invention, and are not an exhaustive list of all embodiments. It should be noted that the embodiments of the present invention and the features thereof may be combined with each other unless they conflict.

[0041] Example 1: Reference Figure 1 Detailed description of this embodiment, an energy-saving intermediate medium vaporizer system includes a seawater inlet 1, a first temperature sensor 2, a vaporizer 3, a second temperature sensor 4, a third temperature sensor 5, a control system 6, a fourth temperature sensor 7, a seawater outlet 8 and a seawater pump 9;

[0042] The vaporizer 3 includes an evaporator E1 and a thermostat E3;

[0043] The seawater pump 9 is connected to the seawater inlet 1, and the seawater inlet 1 is connected to the inlet of the vaporizer 3;

[0044] The first temperature sensor 2 is arranged between the seawater inlet 1 and the inlet of the vaporizer 3;

[0045] The second temperature sensor 4 is arranged above the exhaust port of the gasifier 3;

[0046] The third temperature sensor 5 is arranged on the inner wall of the heat exchange tube of the thermostat E3;

[0047] The fourth temperature sensor 7 is arranged on the inner wall of the heat exchange tube of the evaporator E1;

[0048] The seawater outlet 8 is connected to the outlet of the vaporizer 3;

[0049] The control system 6 is connected to the first temperature sensor 2, the second temperature sensor 4, the third temperature sensor 5, the fourth temperature sensor 7 and the seawater pump 9 respectively. The control system 6 is used to collect the output temperatures of the first temperature sensor 2, the second temperature sensor 4, the third temperature sensor 5 and the fourth temperature sensor 7, and control the start, stop and operating speed of the seawater pump 9.

[0050] Example 2: Reference Figure 1 and Figure 2 Detailed description of this embodiment, a control method for an energy-saving intermediate medium gasifier system includes the following steps:

[0051] S1. Design the intermediate medium vaporizer according to the heat exchange ratio formula and calculate the normal seawater flow rate as the seawater flow rate during normal operation;

[0052] S2. Set the preset seawater inlet temperature as the minimum temperature for energy-saving operation based on the operating conditions, and calculate the energy-saving seawater flow rate as the maximum seawater flow rate during energy-saving operation using the heat exchange ratio formula;

[0053] S3. The control system compares the real-time inlet temperature collected by the first temperature sensor with the preset temperature, and switches the system operation state by adjusting the operating speed of the seawater pump according to the first temperature step judgment condition;

[0054] Specifically:

[0055] The first temperature step judgment condition is: when the real-time inlet temperature collected by the first temperature sensor is less than the preset temperature, the energy-saving intermediate medium vaporizer system remains in normal operation; when the real-time inlet temperature collected by the first temperature sensor is greater than the preset temperature, the control system will reduce the operating speed of the seawater pump to reduce the seawater flow rate, and the energy-saving intermediate medium vaporizer system will switch to energy-saving operation;

[0056] S4. Set the freezing temperature of the inner wall of the evaporator and thermostat heat exchange tubes. The control system compares the real-time evaporator heat exchange tube inner wall temperature collected by the fourth temperature sensor and the real-time thermostat heat exchange tube inner wall temperature collected by the third temperature sensor with the freezing temperature, and adjusts the operating speed of the seawater pump according to the second temperature step judgment condition to ensure system operation;

[0057] Specifically:

[0058] The second temperature step judgment condition is as follows: when the real-time evaporator heat exchange tube inner wall temperature collected by the fourth temperature sensor and the real-time thermostat heat exchange tube inner wall temperature collected by the third temperature sensor are both greater than the freezing temperature, the energy-saving intermediate medium vaporizer system remains in the current operating state; when either the real-time evaporator heat exchange tube inner wall temperature collected by the fourth temperature sensor or the real-time thermostat heat exchange tube inner wall temperature collected by the third temperature sensor is less than the freezing temperature, the control system controls the seawater pump to increase the operating speed and seawater flow rate until the real-time evaporator heat exchange tube inner wall temperature collected by the fourth temperature sensor and the real-time thermostat heat exchange tube inner wall temperature collected by the third temperature sensor are both greater than the freezing temperature;

[0059] S5. The natural gas temperature at the vaporizer exhaust port is set based on user needs. The control system compares the real-time vaporizer exhaust port temperature collected by the second temperature sensor with the natural gas temperature and adjusts the operating speed of the seawater pump according to the third temperature step judgment condition to ensure system operation;

[0060] Specifically:

[0061] The judgment condition for the third temperature step is: when the real-time vaporizer exhaust port temperature collected by the second temperature sensor is greater than the natural gas temperature, the energy-saving intermediate medium vaporizer system remains in the current operating state; when the real-time vaporizer exhaust port temperature collected by the second temperature sensor is less than the natural gas temperature, the control system controls the seawater pump to increase the operating speed and increase the seawater flow rate until the real-time vaporizer exhaust port temperature collected by the second temperature sensor is greater than the natural gas temperature.

[0062] Furthermore, in S1, the heat exchange ratio formula is expressed as:

[0063] Q=c·m'·Δt

[0064] Where Q is the heat transfer capacity in W, c is the specific heat capacity in J / (kg·℃), m' is the medium flow rate in kg / s, and Δt is the temperature difference between the inlet and outlet of the medium in ℃.

[0065] The normal seawater flow rate m'1 is calculated based on the heat exchange ratio formula and the operating data as the seawater flow rate in the normal operating state.

[0066] Furthermore, in S2, a preset temperature of the seawater inlet is set according to the operating condition data, i.e., the minimum temperature for energy-saving operation, and an energy-saving seawater flow rate m'2 corresponding to the minimum temperature for energy-saving operation is calculated according to the heat exchange ratio formula as the maximum seawater flow rate in the energy-saving operation state;

[0067] Specifically, when designing the vaporizer 3, the relatively low seawater inlet and outlet temperatures minimize the temperature difference between the medium inlet and outlet. When the heat exchange capacity of the vaporizer 3 is high, the required seawater flow rate is high, and the load on the seawater pump 9 is high, resulting in energy waste. According to the heat exchange ratio formula, when a higher inlet temperature and heat exchange temperature difference Δt are achieved, the medium flow rate m' will decrease while the heat exchange capacity Q remains unchanged. This reduces the seawater flow rate while maintaining normal system operation, achieving energy savings.

[0068] The energy-saving effect formula is expressed as:

[0069] P=m'·g·H·ρ / η / 3600

[0070] Where P is the pump shaft power in W, g = 9.81 in N / kg, H is the head in m, and ρ is the medium density in kg / m 3, η is efficiency;

[0071] By analyzing the energy-saving effect formula, it is found that the pump shaft power P is proportional to the medium flow rate m'. When the medium flow rate m' is halved, the pump shaft power P consumed will also be reduced by nearly half. In this embodiment, the heat exchange capacity Q1 required to be provided by seawater can be calculated based on the working conditions of liquefied natural gas (LNG) flow rate of 210t / h, LNG inlet temperature of -150℃ and natural gas (NG) outlet temperature of 1℃. Under normal operating conditions, the seawater inlet temperature 1 is 6.85℃, the seawater outlet temperature 8 is 3.2℃, and the seawater inlet and outlet temperature difference Δt1 is 3.65℃. Combined with the seawater specific heat capacity c1, the normal seawater flow rate is calculated according to the heat exchange ratio formula. m'1, set the preset temperature to 10℃, which is the lowest temperature for energy saving, use a thermometer to measure the temperature of seawater outlet 8 to be a℃, substitute it into the heat exchange ratio formula for calculation, and get the energy-saving seawater flow rate m'2; because in summer, the seawater temperature is higher than the preset temperature in most cases, so the system is in energy-saving operation for a long time, saving a lot of electricity; because the temperature of seawater inlet 1 may be much higher than the preset temperature, but the seawater flow rate cannot be reduced indefinitely, in order to ensure safe and energy-saving operation, when the seawater flow rate is reduced to a certain value, it must be stopped, because the reduction of seawater flow rate will cause the flow rate of seawater in the vaporizer 3 to decrease, and the heat exchange coefficient will decrease rapidly, making the evaporator E1 and The temperature of the inner wall of the heat exchange tube of the thermostat E3 drops rapidly, which may cause ice on the tube wall, resulting in a decrease in the overall heat exchange effect, or even cause cracks in the pipe to affect the operation of the system. The calculation amount of the specific value by changing the working condition is large, which is easy to cause large errors. In addition, the weather temperature and seawater temperature in summer change in real time, making it difficult to accurately calculate the specific value. Therefore, a fourth temperature sensor 7 is set on the inner wall of the heat exchange tube of the evaporator E1 of the vaporizer 3, and a third temperature sensor 5 is set on the inner wall of the heat exchange tube of the thermostat E3. Two feedback signals are added to the control system 6. The control system 6 sets a chain signal. When any of the collected temperatures of the fourth temperature sensor 7 and the third temperature sensor 5 is lower than the freezing temperature 0 .5℃, the control system 6 issues an alarm and increases the operating speed of the seawater pump 9 to stop the reduction of the seawater flow rate. The control system 6 collects the output value of the second temperature sensor 4 and interlocks it with the natural gas exhaust port temperature of the vaporizer 3. When the real-time vaporizer exhaust port temperature collected by the second temperature sensor 4 is lower than the natural gas temperature required by the user by 1.5℃, the control system 6 issues an alarm and increases the operating speed of the seawater pump 9 to stop the reduction of the seawater flow rate, thereby ensuring the normal realization of the gasification function. The control system 6 can be controlled by a multi-function controller based on an 8032 single-chip microcomputer, and the alarm information and current seawater flow rate can be displayed on the screen to facilitate the operator to query operation problems.

[0072] Although the present invention has been described with respect to a limited number of embodiments, it will be apparent to those skilled in the art, having benefit of the foregoing description, that other embodiments are contemplated within the scope of the invention thus described. Furthermore, it should be noted that the language used in this specification has been selected primarily for readability and didactic purposes, rather than for the purpose of explaining or limiting the subject matter of the present invention. Consequently, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the present invention is intended to be illustrative rather than restrictive of the scope of the invention, which is defined by the appended claims.

Claims

1. A control method for an energy-saving intermediate medium gasifier system, characterized in that: The energy-saving intermediate medium vaporizer system comprises a seawater inlet (1), a first temperature sensor (2), a vaporizer (3), a second temperature sensor (4), a third temperature sensor (5), a control system (6), a fourth temperature sensor (7), a seawater outlet (8) and a seawater pump (9); The vaporizer (3) includes an evaporator (E1) and a thermostat (E3); The seawater pump (9) is connected to the seawater inlet (1), and the seawater inlet (1) is connected to the inlet of the vaporizer (3); The first temperature sensor (2) is arranged between the seawater inlet (1) and the inlet of the vaporizer (3); The second temperature sensor (4) is arranged above the exhaust port of the gasifier (3); The third temperature sensor (5) is arranged on the inner wall of the heat exchange tube of the thermostat (E3); The fourth temperature sensor (7) is arranged on the inner wall of the heat exchange tube of the evaporator (E1); The seawater outlet (8) is connected to the outlet of the vaporizer (3); The control system (6) is connected to the first temperature sensor (2), the second temperature sensor (4), the third temperature sensor (5), the fourth temperature sensor (7) and the seawater pump (9), respectively. The control system (6) is used to collect the output temperatures of the first temperature sensor (2), the second temperature sensor (4), the third temperature sensor (5) and the fourth temperature sensor (7), and to control the start, stop and operating speed of the seawater pump (9); A control method for an energy-saving intermediate medium gasifier system includes the following steps: S1. Design the intermediate medium vaporizer according to the heat exchange ratio formula and calculate the normal seawater flow rate as the seawater flow rate during normal operation; S2. Set the preset seawater inlet temperature as the minimum temperature for energy-saving operation based on the operating conditions, and calculate the energy-saving seawater flow rate as the maximum seawater flow rate during energy-saving operation using the heat exchange ratio formula; S3. The control system compares the real-time inlet temperature collected by the first temperature sensor with the preset temperature, and switches the system operation state by adjusting the operating speed of the seawater pump according to the first temperature step judgment condition; Specifically: The first temperature step judgment condition is: when the real-time inlet temperature collected by the first temperature sensor is less than the preset temperature, the energy-saving intermediate medium vaporizer system remains in normal operation; when the real-time inlet temperature collected by the first temperature sensor is greater than the preset temperature, the control system will reduce the operating speed of the seawater pump to reduce the seawater flow rate, and the energy-saving intermediate medium vaporizer system will switch to energy-saving operation; S4. Set the freezing temperature of the inner wall of the evaporator and thermostat heat exchange tubes. The control system compares the real-time evaporator heat exchange tube inner wall temperature collected by the fourth temperature sensor and the real-time thermostat heat exchange tube inner wall temperature collected by the third temperature sensor with the freezing temperature, and adjusts the operating speed of the seawater pump according to the second temperature step judgment condition to ensure system operation; Specifically: The second temperature step judgment condition is as follows: when the real-time evaporator heat exchange tube inner wall temperature collected by the fourth temperature sensor and the real-time thermostat heat exchange tube inner wall temperature collected by the third temperature sensor are both greater than the freezing temperature, the energy-saving intermediate medium vaporizer system remains in the current operating state; when either the real-time evaporator heat exchange tube inner wall temperature collected by the fourth temperature sensor or the real-time thermostat heat exchange tube inner wall temperature collected by the third temperature sensor is less than the freezing temperature, the control system controls the seawater pump to increase the operating speed and seawater flow rate until the real-time evaporator heat exchange tube inner wall temperature collected by the fourth temperature sensor and the real-time thermostat heat exchange tube inner wall temperature collected by the third temperature sensor are both greater than the freezing temperature; S5. The natural gas temperature at the vaporizer exhaust port is set based on user needs. The control system compares the real-time vaporizer exhaust port temperature collected by the second temperature sensor with the natural gas temperature and adjusts the operating speed of the seawater pump according to the third temperature step judgment condition to ensure system operation; Specifically: The judgment condition for the third temperature step is: when the real-time vaporizer exhaust port temperature collected by the second temperature sensor is greater than the natural gas temperature, the energy-saving intermediate medium vaporizer system remains in the current operating state; when the real-time vaporizer exhaust port temperature collected by the second temperature sensor is less than the natural gas temperature, the control system controls the seawater pump to increase the operating speed and increase the seawater flow rate until the real-time vaporizer exhaust port temperature collected by the second temperature sensor is greater than the natural gas temperature.

2. The control method of an energy-saving intermediate medium gasifier system according to claim 1, characterized in that: In S1, the heat exchange ratio formula is expressed as: ； in, is the heat transfer, unit is , is the specific heat capacity, in units of , is the medium flow rate, in units of , is the temperature difference between the inlet and outlet of the medium, in units of ; Calculate the normal seawater flow rate based on the heat exchange ratio formula and operating data As the seawater flow rate during normal operation.

3. The control method of an energy-saving intermediate medium gasifier system according to claim 2, characterized in that: In S2, the preset temperature of the seawater inlet is set according to the working condition data, that is, the minimum temperature for energy-saving operation, and the energy-saving seawater flow corresponding to the minimum temperature for energy-saving operation is calculated according to the heat exchange ratio formula. This is the maximum seawater flow rate during energy-saving operation.

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