Low temperature tank farm ethylene system

Abstract

The utility model discloses a low temperature tank area ethylene system, it includes low temperature ethylene storage tank, ethylene incoming pipeline is equipped with valve group I and valve group II on it, outgoing pipeline is equipped with pump group I, pump group II, valve group III, reheater, valve group IV and valve I on it, gas phase reliquefaction pipeline is equipped with compressor, cooler, valve group V, refrigerator I, valve II, ethylene condensate receiving tank, valve III and valve IV on it, back material pipeline is equipped with valve V, valve VI, valve VII, refrigerator II and valve group VI on it, refrigerator II refrigerant supplement pipeline is equipped with valve VIII and valve IX on it, refrigerator II feed pipeline is equipped with valve X on it, the low temperature tank area ethylene system of this utility model adds refrigerator II refrigerant supplement pipeline and refrigerator II feed pipeline, realizes reheating external transmission and reliquefaction process parallel operation, can reduce ethylene condensate tank temperature from -40 DEG C to -75 DEG C under reheating condition, and the flash evaporation amount reduces more than 30 DEG C.

Description

Technical Field

[0001] This utility model relates to the field of cryogenic ethylene feedstock processing technology, specifically a cryogenic tank farm ethylene system. Background Technology

[0002] Several technical issues exist in the operation of the existing cryogenic tank farm ethylene system, as follows: (1) Insufficient safety: The refrigerant charge of the cascade refrigeration unit relies on the metal hose to transport liquefied hydrocarbons (ethylene), which poses safety risks such as leakage and fire.

[0003] (2) System process conflict: The process from the propylene chiller to the cascade chiller and the ethylene reheating and export process share a pipeline section, which means that when the reheating system is put into operation, it is impossible to send the -40℃ ethylene condensate to the cascade chiller to cool it down to -75℃ and return it to the tank, which restricts the reliquefaction capacity of the low-temperature ethylene system under reheating conditions.

[0004] (3) Limited pressure control of storage tanks: When reheating and transporting ethylene condensate back to the tank, the temperature is high (around -40℃) and the flash evaporation is large, which can easily lead to a continuous rise in the pressure of the low-temperature ethylene storage tank, which may affect the core operations such as receiving materials and unloading ships, and reduce the emergency support capability of the system.

[0005] To address the aforementioned issues, technical improvements are needed to the currently implemented cryogenic tank farm ethylene system to meet operational requirements. Utility Model Content

[0006] The technical problem to be solved by this utility model is to address the shortcomings of the existing technology by providing a cryogenic tank ethylene system that enables the parallel operation of reheating and reliquefaction processes. Under reheating conditions, the temperature of ethylene condensate returning to the tank can be reduced from -40°C to -75°C, the flash evaporation amount can be reduced by more than 30°C, the stability of pressure control in cryogenic storage tanks can be improved, and the reception and unloading operations can be avoided due to excessive pressure.

[0007] The technical problem to be solved by this utility model is achieved through the following technical solution: a cryogenic tank farm ethylene system, which includes cryogenic ethylene storage tanks; The ethylene feed pipeline is connected at one end to the cryogenic ethylene storage tank. Valve group I and valve group II are installed on it in sequence according to the feeding direction. Pump group I is located at the bottom of the cryogenic ethylene storage tank. The discharge pipeline is equipped with pump group I, pump group II, valve group III, reheater, valve group IV and valve I in sequence according to the feeding direction; The gas phase reliquefaction pipeline is connected to the top of the cryogenic ethylene storage tank at both its inlet and outlet ends. The tank is equipped with a compressor, cooler, valve group V, refrigeration unit I, valve II, ethylene condensate receiving tank, valve III and valve IV in sequence according to the material conveying direction. The return pipeline has one end connected to the discharge pipeline between valve group IV and valve I, and the other end connected to the ethylene feed pipeline between valve group I and valve group II. The return pipeline is equipped with valve V, valve VI, valve VII, refrigeration unit II and valve group VI in sequence according to the feeding direction. The refrigerant supply line for refrigeration unit II has one end connected to the vapor phase reliquefaction line between valve III and valve IV, and the other end connected to the refrigerant line of refrigeration unit II. It is equipped with valve VIII and valve IX in sequence according to the material conveying direction. The feed line for refrigeration unit II has one end connected to the refrigerant supply line for refrigeration unit II between valves VIII and IX, and the other end connected to the return line between valves VI and VII, with valve X installed on it.

[0008] The technical problem to be solved by this utility model can also be achieved through the following technical solution: In the above-mentioned cryogenic tank area ethylene system, the pump group I is a submersible pump.

[0009] The technical problem to be solved by this utility model can also be achieved through the following technical solution: in the above-mentioned cryogenic tank area ethylene system, the pump group II is a booster pump.

[0010] The technical problem to be solved by this utility model can also be achieved through the following technical solution: the cryogenic tank area ethylene system described above, wherein the refrigeration unit I is a propylene refrigeration unit.

[0011] The technical problem to be solved by this utility model can also be achieved through the following technical solution: the cryogenic tank area ethylene system described above, wherein the refrigeration unit II is a cascade refrigeration unit.

[0012] The technical problem to be solved by this utility model can also be achieved through the following technical solution: the above-mentioned cryogenic tank area ethylene system, wherein the reheater includes an ethylene heater and a methanol heater. The inlet and outlet of the ethylene heater are connected to the discharge pipeline; The methanol heater has a methanol feed pipe connected to its tube side inlet, and its tube side outlet is connected to the shell side of the ethylene heater. The methanol heater has a hot steam line connected to its shell side inlet, and a condensate discharge line connected to its shell side outlet.

[0013] Compared with the prior art, the beneficial technical effects of this utility model are: The refrigerant supply pipeline and feed pipeline of the refrigeration unit II added to the ethylene system of the cryogenic tank area can simultaneously carry out ethylene material reheating and external transportation as well as gas phase reliquefaction operations. On the one hand, under the reheating condition, the temperature of ethylene condensate returning to the tank can be reduced from -40℃ to -75℃, the flash evaporation amount is reduced by more than 30%, the stability of pressure control in the low temperature storage tank is improved, and the receiving and unloading operations are avoided due to excessive pressure. On the other hand, it also improves the safety of refrigerant charging operations for Refrigeration Unit II, completely eliminating the safety hazards previously caused by conveying refrigerant through liquefied hydrocarbon hoses, and increasing refrigerant charging efficiency by 40%. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the pipeline of this utility model; Figure 2 This is a schematic diagram of another pipeline of this utility model.

[0015] Reference numerals in the attached diagram: 1. Cryogenic ethylene storage tank; 2. Ethylene inlet pipeline; 3. Valve group I; 4. Valve group II; 5. Pump group I; 6. Pump group II; 7. Valve group III; 8. Reheater; 9. Valve group IV; 10. Valve I; 11. Discharge pipeline; 12. Vapor phase reliquefaction pipeline; 13. Compressor; 14. Cooler; 15. Valve group V; 16. Refrigeration unit I; 17. Valve II; 18. Ethylene condensate receiving tank; 19. Valve III; 20. Valve IV; 21. Return pipeline; 22. Valve V; 23. Valve VI; 24. Valve VII; 25. Refrigeration unit II; 26. Valve group VI; 27. Refrigeration unit II refrigerant supply pipeline; 28. Valve VIII; 29. ​​Valve IX; 30. Refrigeration unit II feed pipeline; 31. Valve X. Detailed Implementation

[0016] The specific technical solutions of this utility model are further described below with reference to the accompanying drawings, so as to enable those skilled in the art to further understand this utility model, without constituting a limitation on its rights.

[0017] Example 1, referring to Figure 1-2 A cryogenic tank farm ethylene system, comprising a cryogenic ethylene storage tank 1 for temporary storage of cryogenic ethylene arriving from the wharf. Ethylene feed pipeline 2 is used to receive ethylene feed transported from the dock. One end of it is connected to the cryogenic ethylene storage tank 1. Valve group I 3 and valve group II 4 are installed on it in sequence according to the feeding direction. Pump group I is located in the bottom of cryogenic ethylene storage tank 1. The valve group and the pump group below consist of multiple valves and pumps. Their quantity and model can be selected according to the usage requirements. The discharge pipeline 11 is equipped with pump group I5, pump group II6, valve group III7, reheater 8, valve group IV9 and valve I10 in sequence according to the feeding direction. Pump group I5 is a submersible pump, pump group II6 is a booster pump. Pump group I5 is used to pump the ethylene material in the low temperature ethylene storage tank 1 to the downstream process, pump group II6 is used to pressurize and transport the ethylene material, and reheater 8 is used to heat the low temperature ethylene. The gas phase reliquefaction pipeline 12 is used to reliquefy the gas phase ethylene accumulated in the low-temperature ethylene storage tank 1. It is located outside the low-temperature ethylene storage tank 1, and its inlet and outlet ends are connected to the top of the low-temperature ethylene storage tank. In the material conveying direction, it is equipped with a compressor 13, a cooler 14, a valve group V 15, a chiller I 16, a valve II 17, an ethylene condensate receiving tank 18, a valve III 19 and a valve IV 20. The chiller I 16 is a propylene chiller. The return pipeline 21 has one end connected to the discharge pipeline 11 between valve group IV9 and valve I10, and the other end connected to the ethylene feed pipeline 2 between valve group I3 and valve group II4. The return pipeline 21 is provided with valve V22, valve VI23, valve VII24, chiller II25 and valve group VI26 in sequence according to the feeding direction. The chiller II25 is a cascade chiller. The refrigerant supply line 27 for refrigeration unit II is used to replenish refrigerant to refrigeration unit II 25. One end of the line is connected to the vapor phase reliquefaction line 12 between valve III 19 and valve IV 20, and the other end is connected to the refrigerant pipeline of refrigeration unit II 25. It is equipped with valve VIII 28 and valve IX 29 in sequence according to the material conveying direction. The refrigeration unit II feed line 30 is used to transport ethylene to be cooled. One end of it is connected to the refrigeration unit II refrigerant supply line 27 between valve VIII 28 and valve IX 29, and the other end is connected to the return line 21 between valve VI 23 and valve VII 24. Valve X 31 is installed on it.

[0018] The models and specifications of valves I10 to X31 in Example 1 are all existing technologies, and users can choose their own models and specifications according to their needs.

[0019] Example 2, a cryogenic tank farm ethylene system as described in Example 1, wherein the reheater 8 includes an ethylene heater and a methanol heater; The inlet and outlet of the ethylene heater are connected to the discharge pipeline 11; The methanol heater has a methanol feed pipe connected to its tube side inlet, and its tube side outlet is connected to the shell side of the ethylene heater. The methanol heater has a hot steam line connected to its shell side inlet, and a condensate discharge line connected to its shell side outlet.

[0020] In Example 2, the methanol in the methanol heater is heated by external hot steam. The heated methanol changes from a liquid phase to a gas phase. After encountering low-temperature ethylene, it exchanges heat with it and is cooled to a liquefied state. The ethylene that participated in the heat exchange is then reheated to -35°C.

[0021] The operating principle of the cryogenic tank farm ethylene system in Examples 1-2 is as follows: The ethylene material arriving at the terminal first enters the cryogenic ethylene storage tank 1 through the ethylene material pipeline 2, and is then transported to downstream facilities through the discharge pipeline 11. When the ethylene feed material does not reach the discharge temperature, valve I10 is closed and the discharge is stopped. At this time, the ethylene feed material enters the return pipeline 21 and is cooled down by the refrigeration unit II25 in the return pipeline 21. When gaseous ethylene material accumulates in the top of the low-temperature ethylene storage tank 1, valve group V15, valve II17, valve III19 and valve IV20 are opened, and the gaseous ethylene material is cooled and reliquefied by the gas phase reliquefaction pipeline 12. During this period, valve V22 and valve VIII28 can be kept closed, so that the discharge pipeline 11 and the gas phase reliquefaction pipeline 12 can be operated simultaneously, that is, the reheating and external transportation and the reliquefaction process can be operated in parallel. In addition, before running the refrigeration unit II 25, refrigerant can be replenished. During replenishment, keep valves III 19, VIII 28, and IX 29 open, and keep valves IV 20 and X 31 closed. At this time, the liquid ethylene material from the ethylene condensate receiving tank 18 is discharged into the refrigeration unit II 25 to replenish the refrigerant in the refrigeration unit II 25. After the refrigerant is replenished, close valve IX 29, keep valves IV 20 and VI 23 closed, and keep valves III 19, VIII 28, X 31, and VII 24 open. At this time, the ethylene condensate receiving tank 18 discharges into the refrigeration unit II 25 for further cooling, thereby reducing the flash evaporation after the condensate returns to the tank, improving the pressure reduction effect, and maximizing the reliquefaction capacity.

Claims

1. A cryogenic tank farm ethylene system, characterized in that: It includes cryogenic ethylene storage tanks; The ethylene feed pipeline is connected at one end to a cryogenic ethylene storage tank, and valve group I and valve group II are installed on it in sequence according to the feeding direction. The discharge pipeline is equipped with pump group I, pump group II, valve group III, reheater, valve group IV and valve I in sequence according to the feeding direction. Pump group I is located at the bottom of the low temperature ethylene storage tank. The gas phase reliquefaction pipeline is connected to the top of the cryogenic ethylene storage tank at both its inlet and outlet ends. The tank is equipped with a compressor, cooler, valve group V, refrigeration unit I, valve II, ethylene condensate receiving tank, valve III and valve IV in sequence according to the material conveying direction. The return pipeline has one end connected to the discharge pipeline between valve group IV and valve I, and the other end connected to the ethylene feed pipeline between valve group I and valve group II. The return pipeline is equipped with valve V, valve VI, valve VII, refrigeration unit II and valve group VI in sequence according to the feeding direction. The refrigerant supply line for refrigeration unit II has one end connected to the vapor phase reliquefaction line between valve III and valve IV, and the other end connected to the refrigerant line of refrigeration unit II. It is equipped with valve VIII and valve IX in sequence according to the material conveying direction. The feed line for refrigeration unit II has one end connected to the refrigerant supply line for refrigeration unit II between valves VIII and IX, and the other end connected to the return line between valves VI and VII, with valve X installed on it.

2. The cryogenic tank farm ethylene system according to claim 1, characterized in that: The pump unit I is a submersible pump.

3. The cryogenic tank farm ethylene system according to claim 1, characterized in that: The pump unit II is a booster pump.

4. A cryogenic tank farm ethylene system according to claim 1, characterized in that: The aforementioned refrigeration unit I is a propylene refrigeration unit.

5. A cryogenic tank farm ethylene system according to claim 1, characterized in that: The aforementioned refrigeration unit II is a cascade refrigeration unit.

6. A cryogenic tank farm ethylene system according to claim 1, characterized in that: The reheater includes an ethylene heater and a methanol heater; The inlet and outlet of the ethylene heater are connected to the discharge pipeline; The methanol heater has a methanol feed pipe connected to its tube side inlet, a methanol outlet connected to the shell side of the ethylene heater, a hot steam line connected to its shell side inlet, and a condensate discharge line connected to its shell side outlet.

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