Chilled water precooling energy optimization system of coal-to-ethanol device

Abstract

The utility model provides a chilled water precooling energy optimization system of a coal-to-ethanol device. Comprising a first dimethyl ether tower top heat exchanger, a second dimethyl ether tower top heat exchanger, a first ethyl alcohol methyl ester tower top heat exchanger, a second ethyl alcohol methyl ester tower top heat exchanger, a first ethyl alcohol tower top heat exchanger, a second ethyl alcohol tower top heat exchanger, a chilled water circulation assembly and a lithium bromide unit. Process materials flowing through a first heat exchanger at the top of a dimethyl ether tower, a first heat exchanger at the top of an ethyl alcohol methyl ester tower and a first heat exchanger at the top of an ethyl alcohol tower are firstly cooled through a lithium bromide unit; then process materials flowing through the second heat exchanger at the top of the dimethyl ether tower, the second heat exchanger at the top of the ethyl alcohol methyl ester tower and the second heat exchanger at the top of the ethyl alcohol tower are firstly cooled through the chilled water circulation assembly, so that the temperature difference between a cooling medium and a process medium of the heat exchangers is reduced compared with the temperature difference in the prior art, and the heat exchange efficiency is improved; and equipment faults of the heat exchanger are reduced, and the purpose of reducing energy consumption is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of petrochemical industry, in particular to a chilled water precooling energy optimization system for a coal-to-ethanol device. Background Art

[0002] Ethanol is not only an important basic chemical, but also closely related to people's daily life. It can be used to make beverages, flavors, disinfectants, etc. Anhydrous ethanol can be used as a gasoline additive, namely fuel ethanol, which can effectively improve the quality of gasoline and significantly reduce vehicle pollutant emissions.

[0003] Using coal-based synthesis gas as raw material, methanol and dimethyl ether carbonylation and hydrogenation are used to synthesize ethanol. This route uses non-precious metal catalysts and can directly produce anhydrous ethanol. It is an environmentally friendly technical route. The technical route of coal-to-synthesis gas, synthesis gas through methanol dehydration, dimethyl ether carbonylation, and methyl acetate hydrogenation (DMTE) process is divided into three steps (such as Figure 1 shown):

[0004] Step 1: Dehydration of methanol to produce dimethyl ether;

[0005] Step 2: Methanol carbonylation reaction produces methyl acetate.

[0006] Step 3: Methyl acetate is hydrogenated to produce ethanol.

[0007] Figure 2 Schematic diagram of the dimethyl ether tower distillation process, the process material with a temperature of 38.63°C at the top of the dimethyl ether tower flows into the dimethyl ether tower top heat exchanger, and the chilled water with a temperature of -15°C flows into the dimethyl ether tower top heat exchanger for heat exchange, and the temperature difference between the cold and hot media in the dimethyl ether tower top heat exchanger is 53.63°C; Figure 3 Schematic diagram of the distillation process of the methyl acetate tower. The process material with a top temperature of 40.45°C of the methyl acetate tower flows into the top heat exchanger of the methyl acetate tower, and the chilled water with a temperature of -15°C flows into the top heat exchanger of the methyl acetate tower for heat exchange. The temperature difference between the cold and hot media of the top heat exchanger of the methyl acetate tower is 55.45°C. Figure 4 Schematic diagram of the distillation process of the ethanol tower; process materials with a top temperature of 42.5°C flow into the top heat exchanger of the ethanol tower, and chilled water with a temperature of -15°C flows into the top heat exchanger of the ethanol tower for heat exchange, and the temperature difference between the cold and hot media in the top heat exchanger of the ethanol tower is 57.5°C.

[0008] The above-mentioned large temperature difference heat exchange process has the following disadvantages: First, the heat exchange efficiency decreases: the large temperature difference of the heat exchanger reduces the heat transfer of the hot fluid and the heat transfer efficiency is low. When the temperature difference is too large, the equipment can only work at a lower heat exchange efficiency, affecting the temperature control and production efficiency of the fluid. Second, equipment wear is aggravated: the large temperature difference of the heat exchanger causes a large temperature change inside the equipment, which causes thermal expansion and thermal contraction, resulting in stress concentration, fatigue cracking and other problems inside the equipment, resulting in shortened equipment life, increased wear and other problems. Third, energy waste: the operation of the heat exchanger requires a lot of energy. When the temperature difference is too large, it not only consumes more energy, but also causes energy waste, which is not conducive to energy conservation. Summary of the invention

[0009] In view of this, the utility model provides a chilled water precooling energy optimization system for a coal-to-ethanol device to solve the problems described in the prior art.

[0010] A chilled water precooling energy optimization system for a coal-to-ethanol device comprises a first heat exchanger at the top of a dimethyl ether tower, a second heat exchanger at the top of a dimethyl ether tower, a first heat exchanger at the top of an ethanol methyl ester tower, a second heat exchanger at the top of an ethanol methyl ester tower, a first heat exchanger at the top of an ethanol tower, a second heat exchanger at the top of an ethanol tower, a chilled water circulation component and a lithium bromide unit; a process material inlet end of the first heat exchanger at the top of the dimethyl ether tower is connected to a process material outlet end of the dimethyl ether tower, a process material outlet end of the first heat exchanger at the top of the dimethyl ether tower is connected to a process material inlet end of the second heat exchanger at the top of the dimethyl ether tower, and a process material outlet end of the first heat exchanger at the top of the dimethyl ether tower is connected to a process material inlet end of the second heat exchanger at the top of the dimethyl ether tower. The cooling liquid inlet of the first heat exchanger is connected to the cooling liquid outlet of the lithium bromide unit, the cooling liquid outlet of the first heat exchanger at the top of the dimethyl ether tower is connected to the cooling liquid reflux end of the lithium bromide unit, the cooling liquid inlet of the second heat exchanger at the top of the dimethyl ether tower is connected to the cooling liquid outlet of the chilled water circulation component, and the cooling liquid outlet of the second heat exchanger at the top of the dimethyl ether tower is connected to the cooling liquid reflux end of the chilled water circulation component; the process material inlet of the first heat exchanger at the top of the ethanol methyl ester tower is connected to the process material outlet of the top of the ethanol methyl ester tower, and the process material flow of the first heat exchanger at the top of the ethanol methyl ester tower is connected. The outlet end is connected to the process material inlet end of the second heat exchanger at the top of the ethanol methyl ester tower, the coolant inlet end of the first heat exchanger at the top of the ethanol methyl ester tower is connected to the coolant outflow end of the lithium bromide unit, the coolant outflow end of the first heat exchanger at the top of the ethanol methyl ester tower is connected to the coolant reflux end of the lithium bromide unit, the coolant inlet end of the second heat exchanger at the top of the ethanol methyl ester tower is connected to the coolant outflow end of the chilled water circulation component, and the coolant outflow end of the second heat exchanger at the top of the ethanol methyl ester tower is connected to the coolant reflux end of the chilled water circulation component; the process material inlet end of the first heat exchanger at the top of the ethanol tower is connected to the ethanol The process material outflow end of the tower top is connected, the process material outflow end of the first heat exchanger at the top of the ethanol tower is connected to the process material inlet end of the second heat exchanger at the top of the ethanol tower, the coolant inlet end of the first heat exchanger at the top of the ethanol tower is connected to the coolant outflow end of the lithium bromide unit, the coolant outflow end of the first heat exchanger at the top of the ethanol tower is connected to the coolant reflux end of the lithium bromide unit, the coolant inlet end of the second heat exchanger at the top of the ethanol tower is connected to the coolant outflow end of the chilled water circulation component, and the coolant outflow end of the second heat exchanger at the top of the ethanol tower is connected to the coolant reflux end of the chilled water circulation component.

[0011] Preferably, a first pressure sensor and a first temperature sensor are arranged on the process material inlet pipe of the first heat exchanger at the top of the dimethyl ether tower, a second temperature sensor is arranged on the coolant inlet pipe of the first heat exchanger at the top of the dimethyl ether tower, a second pressure sensor is arranged on the coolant outflow pipe of the first heat exchanger at the top of the dimethyl ether tower, and a third pressure sensor and a third temperature sensor are arranged on the connecting pipe between the process material outflow end of the first heat exchanger at the top of the dimethyl ether tower and the process material inlet end of the second heat exchanger at the top of the dimethyl ether tower.

[0012] Preferably, a first control valve is provided on the coolant inlet pipe of the first heat exchanger at the top of the dimethyl ether tower, and the first control valve is electrically connected to the first temperature sensor.

[0013] Preferably, a fourth pressure sensor and a fourth temperature sensor are arranged on the process material inlet pipe of the first heat exchanger at the top of the ethanol methyl ester tower, a fifth temperature sensor is arranged on the coolant inlet pipe of the first heat exchanger at the top of the ethanol methyl ester tower, a fifth pressure sensor is arranged on the coolant outflow pipe of the first heat exchanger at the top of the ethanol methyl ester tower, and a sixth pressure sensor and a sixth temperature sensor are arranged on the connecting pipe between the process material outflow end of the first heat exchanger at the top of the ethanol methyl ester tower and the process material inlet end of the second heat exchanger at the top of the ethanol methyl ester tower.

[0014] Preferably, a second control valve is provided on the coolant inlet pipe of the first heat exchanger at the top of the ethanol methyl ester tower, and the second control valve is electrically connected to the fourth temperature sensor.

[0015] Preferably, a seventh pressure sensor and a seventh temperature sensor are arranged on the process material inlet pipe of the first heat exchanger at the top of the ethanol tower, an eighth temperature sensor is arranged on the coolant inlet pipe of the first heat exchanger at the top of the ethanol tower, an eighth pressure sensor is arranged on the coolant outlet pipe of the first heat exchanger at the top of the ethanol tower, and a ninth pressure sensor and a ninth temperature sensor are arranged on the connecting pipe between the process material outflow end of the first heat exchanger at the top of the ethanol tower and the process material inlet end of the second heat exchanger at the top of the ethanol tower.

[0016] Preferably, a third control valve is provided on the coolant inlet pipe of the first heat exchanger at the top of the ethanol tower, and the third control valve is electrically connected to the seventh temperature sensor.

[0017] Preferably, the first heat exchanger at the top of the dimethyl ether tower, the first heat exchanger at the top of the ethanol methyl ester tower, and the first heat exchanger at the top of the ethanol tower are all shell and tube heat exchangers.

[0018] Compared with the prior art, the utility model has the following beneficial effects: the process materials flowing through the first heat exchanger at the top of the dimethyl ether tower, the first heat exchanger at the top of the ethanol methyl ester tower, and the first heat exchanger at the top of the ethanol tower are first cooled by the lithium bromide unit, and then the process materials flowing through the second heat exchanger at the top of the dimethyl ether tower, the second heat exchanger at the top of the ethanol methyl ester tower, and the second heat exchanger at the top of the ethanol tower are first cooled by the chilled water circulation component, so that the cooling process forms two-stage cooling, and in each stage of the cooling process, the temperature difference between the cooling medium of the heat exchanger and the process medium is reduced relative to the temperature difference in the prior art, thereby improving the heat exchange efficiency, while reducing the equipment failure caused by the large temperature difference between the cooling medium and the process medium of the heat exchanger, and achieving the purpose of reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1This is the process flow chart of the coal-to-ethanol plant.

[0020] Figure 2 It is a structural block diagram of the cooling of process materials at the top of a dimethyl ether tower in the prior art.

[0021] Figure 3 The present invention is a structural block diagram of the cooling of the process materials at the top of the ethanol methyl ester tower in the prior art.

[0022] Figure 4 It is a structural block diagram of the cooling of process materials at the top of an ethanol tower in the prior art.

[0023] Figure 5 It is a structural frame diagram of the utility model.

[0024] In the figure: a first heat exchanger 10 at the top of a dimethyl ether tower, a first pressure sensor 11, a first temperature sensor 12, a second temperature sensor 13, a second pressure sensor 14, a third pressure sensor 15, a third temperature sensor 16, a first control valve 17, a second heat exchanger 20 at the top of a dimethyl ether tower, a first heat exchanger 30 at the top of an ethanol methyl ester tower, a fourth pressure sensor 31, a fourth temperature sensor 32, a fifth temperature sensor 33, a fifth pressure sensor 34, a sixth pressure sensor 35, a sixth temperature sensor 36, a second control valve 37, a second heat exchanger 40 at the top of an ethanol methyl ester tower, a first heat exchanger 50 at the top of an ethanol tower, a seventh pressure sensor 51, a seventh temperature sensor 52, an eighth temperature sensor 53, an eighth pressure sensor 54, a ninth pressure sensor 55, a ninth temperature sensor 56, a third control valve 57, a second heat exchanger 60 at the top of an ethanol tower, a chilled water circulation component 70, and a lithium bromide unit 80. DETAILED DESCRIPTION

[0025] The technical solution and technical effects of the present invention are further described in detail below in conjunction with the accompanying drawings of the present invention.

[0026] See also Figure 5The chilled water precooling energy optimization system of the coal-to-ethanol device comprises a first heat exchanger 10 at the top of a dimethyl ether tower, a second heat exchanger 20 at the top of a dimethyl ether tower, a first heat exchanger 30 at the top of an ethanol methyl ester tower, a second heat exchanger 40 at the top of an ethanol tower, a first heat exchanger 50 at the top of an ethanol tower, a second heat exchanger 60 at the top of an ethanol tower, a chilled water circulation component 70 and a lithium bromide unit 80; the process material inlet end of the first heat exchanger 10 at the top of the dimethyl ether tower is connected to the process material outflow end of the dimethyl ether tower, the process material outflow end of the first heat exchanger 10 at the top of the dimethyl ether tower is connected to the process material inlet end of the second heat exchanger 20 at the top of the dimethyl ether tower, and the dimethyl ether tower top is connected to the process material The cooling liquid inlet of the first heat exchanger 10 is connected to the cooling liquid outlet of the lithium bromide unit 80, the cooling liquid outlet of the first heat exchanger 10 at the top of the dimethyl ether tower is connected to the cooling liquid reflux end of the lithium bromide unit 80, the cooling liquid inlet of the second heat exchanger 20 at the top of the dimethyl ether tower is connected to the cooling liquid outlet of the chilled water circulation component 70, and the cooling liquid outlet of the second heat exchanger 20 at the top of the dimethyl ether tower is connected to the cooling liquid reflux end of the chilled water circulation component 70; the process material inlet of the first heat exchanger 30 at the top of the ethanol methyl ester tower is connected to the process material outlet of the top of the ethanol methyl ester tower, and the process material flow of the first heat exchanger 30 at the top of the ethanol methyl ester tower is connected. The outlet end is connected to the process material inlet end of the second heat exchanger 40 at the top of the ethanol methyl ester tower, the coolant inlet end of the first heat exchanger 30 at the top of the ethanol methyl ester tower is connected to the coolant outflow end of the lithium bromide unit 80, the coolant outflow end of the first heat exchanger 30 at the top of the ethanol methyl ester tower is connected to the coolant reflux end of the lithium bromide unit 80, the coolant inlet end of the second heat exchanger 40 at the top of the ethanol methyl ester tower is connected to the coolant outflow end of the chilled water circulation component 70, and the coolant outflow end of the second heat exchanger 40 at the top of the ethanol methyl ester tower is connected to the coolant reflux end of the chilled water circulation component 70; the process material inlet end of the first heat exchanger 50 at the top of the ethanol tower is connected to the ethanol The process material outflow end of the tower top is connected, the process material outflow end of the first heat exchanger 50 at the top of the ethanol tower is connected to the process material inlet end of the second heat exchanger 60 at the top of the ethanol tower, the coolant inlet end of the first heat exchanger 50 at the top of the ethanol tower is connected to the coolant outflow end of the lithium bromide unit 80, the coolant outflow end of the first heat exchanger 50 at the top of the ethanol tower is connected to the coolant reflux end of the lithium bromide unit 80, the coolant inlet end of the second heat exchanger 60 at the top of the ethanol tower is connected to the coolant outflow end of the chilled water circulation component 70, and the coolant outflow end of the second heat exchanger 60 at the top of the ethanol tower is connected to the coolant reflux end of the chilled water circulation component 70.

[0027] The process materials flowing through the first heat exchanger at the top of the dimethyl ether tower, the first heat exchanger at the top of the ethanol methyl ester tower, and the first heat exchanger at the top of the ethanol tower are first cooled by the lithium bromide unit, and then the process materials flowing through the second heat exchanger at the top of the dimethyl ether tower, the second heat exchanger at the top of the ethanol methyl ester tower, and the second heat exchanger at the top of the ethanol tower are first cooled by the chilled water circulation component, so that the cooling process forms two stages of cooling. In each stage of cooling, the temperature difference between the cooling medium of the heat exchanger and the process medium is reduced compared with the temperature difference in the prior art, thereby improving the heat exchange efficiency, while reducing equipment failures caused by the large temperature difference between the cooling medium and the process medium of the heat exchanger, and achieving the purpose of reducing energy consumption.

[0028] Furthermore, a first pressure sensor 11 and a first temperature sensor 12 are arranged on the process material inlet pipe of the first heat exchanger 10 at the top of the dimethyl ether tower, a second temperature sensor 13 is arranged on the coolant inlet pipe of the first heat exchanger 10 at the top of the dimethyl ether tower, a second pressure sensor 14 is arranged on the coolant outlet pipe of the first heat exchanger 10 at the top of the dimethyl ether tower, and a third pressure sensor 15 and a third temperature sensor 16 are arranged on the connecting pipe between the process material outflow end of the first heat exchanger 10 at the top of the dimethyl ether tower and the process material inlet end of the second heat exchanger 20 at the top of the dimethyl ether tower.

[0029] Wherein, a first control valve 17 is provided on the coolant inlet pipe of the first heat exchanger 10 at the top of the dimethyl ether tower, and the first control valve 17 is electrically connected to the first temperature sensor 12. When the first temperature sensor 12 detects that the temperature of the process material entering the first heat exchanger 10 at the top of the dimethyl ether tower is higher than the set target temperature value, the opening of the first control valve 17 increases to allow more coolant to flow into the first heat exchanger 10 at the top of the dimethyl ether tower, so as to improve the cooling efficiency. When the first temperature sensor 12 detects that the temperature of the process material entering the first heat exchanger 10 at the top of the dimethyl ether tower is lower than the set target temperature value, the opening of the first control valve 17 decreases to allow less coolant to flow into the first heat exchanger 10 at the top of the dimethyl ether tower, so as to reduce the cooling efficiency.

[0030] Furthermore, a fourth pressure sensor 31 and a fourth temperature sensor 32 are arranged on the process material inlet pipe of the first heat exchanger 30 at the top of the ethanol methyl ester tower, a fifth temperature sensor 33 is arranged on the coolant inlet pipe of the first heat exchanger 30 at the top of the ethanol methyl ester tower, a fifth pressure sensor 34 is arranged on the coolant outflow pipe of the first heat exchanger 30 at the top of the ethanol methyl ester tower, and a sixth pressure sensor 35 and a sixth temperature sensor 36 are arranged on the connecting pipe between the process material outflow end of the first heat exchanger 30 at the top of the ethanol methyl ester tower and the process material inlet end of the second heat exchanger 40 at the top of the ethanol methyl ester tower.

[0031] Wherein, a second control valve 37 is provided on the coolant inlet pipe of the first heat exchanger 30 at the top of the ethanol methyl ester tower, and the second control valve 37 is electrically connected to the fourth temperature sensor 32. When the fourth temperature sensor 32 detects that the temperature of the process material entering the first heat exchanger 30 at the top of the ethanol methyl ester tower is higher than the set target temperature value, the opening of the second control valve 37 increases to allow more coolant to flow into the first heat exchanger 30 at the top of the ethanol methyl ester tower, so as to improve the cooling efficiency. When the fourth temperature sensor 32 detects that the temperature of the process material entering the first heat exchanger 30 at the top of the ethanol methyl ester tower is lower than the set target temperature value, the opening of the second control valve 37 decreases to allow less coolant to flow into the first heat exchanger 30 at the top of the ethanol methyl ester tower, so as to reduce the cooling efficiency.

[0032] Furthermore, a seventh pressure sensor 51 and a seventh temperature sensor 52 are arranged on the process material inlet pipe of the first heat exchanger 50 at the top of the ethanol tower, an eighth temperature sensor 53 is arranged on the coolant inlet pipe of the first heat exchanger 50 at the top of the ethanol tower, an eighth pressure sensor 54 is arranged on the coolant outlet pipe of the first heat exchanger 50 at the top of the ethanol tower, and a ninth pressure sensor 55 and a ninth temperature sensor 56 are arranged on the connecting pipe between the process material outflow end of the first heat exchanger 50 at the top of the ethanol tower and the process material inlet end of the second heat exchanger 60 at the top of the ethanol tower.

[0033] Among them, a third control valve 57 is provided on the coolant inlet pipe of the first heat exchanger 50 at the top of the ethanol tower, and the third control valve 57 is electrically connected to the seventh temperature sensor 52. When the seventh temperature sensor 52 detects that the temperature of the process material entering the first heat exchanger 50 at the top of the ethanol tower is higher than the set target temperature value, the opening of the third control valve 57 increases to allow more coolant to flow into the first heat exchanger 50 at the top of the ethanol tower, so as to improve the cooling efficiency. When the seventh temperature sensor 52 detects that the temperature of the process material entering the first heat exchanger 50 at the top of the ethanol tower is lower than the set target temperature value, the opening of the third control valve 57 decreases to allow less coolant to flow into the first heat exchanger 50 at the top of the ethanol tower, so as to reduce the cooling efficiency.

[0034] Furthermore, the first heat exchanger at the top of the dimethyl ether tower, the first heat exchanger at the top of the ethanol methyl ester tower, and the first heat exchanger at the top of the ethanol tower are all shell and tube heat exchangers.

Claims

1. A chilled water precooling energy optimization system for a coal-to-ethanol plant, characterized in that: The invention comprises a first heat exchanger at the top of a dimethyl ether tower, a second heat exchanger at the top of a dimethyl ether tower, a first heat exchanger at the top of an ethanol methyl ester tower, a second heat exchanger at the top of an ethanol methyl ester tower, a first heat exchanger at the top of an ethanol tower, a second heat exchanger at the top of an ethanol tower, a chilled water circulation component and a lithium bromide unit; the process material inlet end of the first heat exchanger at the top of the dimethyl ether tower is connected to the process material outlet end of the dimethyl ether tower, the process material outlet end of the first heat exchanger at the top of the dimethyl ether tower is connected to the process material inlet end of the second heat exchanger at the top of the dimethyl ether tower, the coolant inlet end of the first heat exchanger at the top of the dimethyl ether tower is connected to the coolant outlet end of the dimethyl ether tower The coolant outflow end of the lithium unit is connected, the coolant outflow end of the first heat exchanger at the top of the dimethyl ether tower is connected to the coolant reflux end of the lithium bromide unit, the coolant inlet end of the second heat exchanger at the top of the dimethyl ether tower is connected to the coolant outflow end of the chilled water circulation component, and the coolant outflow end of the second heat exchanger at the top of the dimethyl ether tower is connected to the coolant reflux end of the chilled water circulation component; the process material inlet end of the first heat exchanger at the top of the ethanol methyl ester tower is connected to the process material outflow end of the top of the ethanol methyl ester tower, and the process material outflow end of the first heat exchanger at the top of the ethanol methyl ester tower is connected to the top of the ethanol methyl ester tower. The process material inlet end of the second heat exchanger is connected, the coolant inlet end of the first heat exchanger at the top of the ethanol methyl ester tower is connected to the coolant outflow end of the lithium bromide unit, the coolant outflow end of the first heat exchanger at the top of the ethanol methyl ester tower is connected to the coolant reflux end of the lithium bromide unit, the coolant inlet end of the second heat exchanger at the top of the ethanol methyl ester tower is connected to the coolant outflow end of the chilled water circulation component, and the coolant outflow end of the second heat exchanger at the top of the ethanol methyl ester tower is connected to the coolant reflux end of the chilled water circulation component; the process material inlet end of the first heat exchanger at the top of the ethanol tower is connected to the process material inlet end of the first heat exchanger at the top of the ethanol tower The process material outflow end of the first heat exchanger at the top of the ethanol tower is connected to the process material inlet end of the second heat exchanger at the top of the ethanol tower, the coolant inlet end of the first heat exchanger at the top of the ethanol tower is connected to the coolant outflow end of the lithium bromide unit, the coolant outflow end of the first heat exchanger at the top of the ethanol tower is connected to the coolant reflux end of the lithium bromide unit, the coolant inlet end of the second heat exchanger at the top of the ethanol tower is connected to the coolant outflow end of the chilled water circulation component, and the coolant outflow end of the second heat exchanger at the top of the ethanol tower is connected to the coolant reflux end of the chilled water circulation component.

2. The chilled water precooling energy optimization system for a coal-to-ethanol plant according to claim 1, characterized in that: A first pressure sensor and a first temperature sensor are arranged on the process material inlet pipe of the first heat exchanger at the top of the dimethyl ether tower, a second temperature sensor is arranged on the coolant inlet pipe of the first heat exchanger at the top of the dimethyl ether tower, a second pressure sensor is arranged on the coolant outflow pipe of the first heat exchanger at the top of the dimethyl ether tower, and a third pressure sensor and a third temperature sensor are arranged on the connecting pipe between the process material outflow end of the first heat exchanger at the top of the dimethyl ether tower and the process material inlet end of the second heat exchanger at the top of the dimethyl ether tower.

3. The chilled water precooling energy optimization system for a coal-to-ethanol plant according to claim 2, characterized in that: A first control valve is arranged on the coolant inlet pipe of the first heat exchanger at the top of the dimethyl ether tower, and the first control valve is electrically connected to the first temperature sensor.

4. The chilled water precooling energy optimization system for a coal-to-ethanol plant according to claim 1, characterized in that: A fourth pressure sensor and a fourth temperature sensor are arranged on the process material inlet pipe of the first heat exchanger at the top of the ethanol methyl ester tower, a fifth temperature sensor is arranged on the coolant inlet pipe of the first heat exchanger at the top of the ethanol methyl ester tower, a fifth pressure sensor is arranged on the coolant outflow pipe of the first heat exchanger at the top of the ethanol methyl ester tower, and a sixth pressure sensor and a sixth temperature sensor are arranged on the connecting pipe between the process material outflow end of the first heat exchanger at the top of the ethanol methyl ester tower and the process material inlet end of the second heat exchanger at the top of the ethanol methyl ester tower.

5. The chilled water precooling energy optimization system for a coal-to-ethanol plant according to claim 4, characterized in that: A second control valve is provided on the coolant inlet pipe of the first heat exchanger at the top of the ethanol methyl ester tower, and the second control valve is electrically connected to the fourth temperature sensor.

6. The chilled water precooling energy optimization system for a coal-to-ethanol plant according to claim 1, characterized in that: A seventh pressure sensor and a seventh temperature sensor are arranged on the process material inlet pipe of the first heat exchanger at the top of the ethanol tower, an eighth temperature sensor is arranged on the coolant inlet pipe of the first heat exchanger at the top of the ethanol tower, an eighth pressure sensor is arranged on the coolant outflow pipe of the first heat exchanger at the top of the ethanol tower, and a ninth pressure sensor and a ninth temperature sensor are arranged on the connecting pipe between the process material outflow end of the first heat exchanger at the top of the ethanol tower and the process material inlet end of the second heat exchanger at the top of the ethanol tower.

7. The chilled water precooling energy optimization system for a coal-to-ethanol plant according to claim 6, characterized in that: A third control valve is provided on the coolant inlet pipe of the first heat exchanger at the top of the ethanol tower, and the third control valve is electrically connected to the seventh temperature sensor.

8. The chilled water precooling energy optimization system for a coal-to-ethanol plant according to claim 1, characterized in that: The first heat exchanger at the top of the dimethyl ether tower, the first heat exchanger at the top of the ethanol methyl ester tower, and the first heat exchanger at the top of the ethanol tower are all shell and tube heat exchangers.

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