Pre-cooling system of alkane storage tank

Abstract

The utility model discloses an alkane storage tank precooling system which comprises a normal-temperature pressure storage tank and a low-temperature normal-pressure storage tank which are communicated through a conveying pipeline, the conveying pipeline leads to the low-temperature normal-pressure storage tank from the normal-temperature pressure storage tank, a decompression flash evaporation device is arranged on the conveying pipeline, and a tank inlet pipeline in the conveying pipeline after decompression is a precooling pipeline. A spray head is arranged at an output port of the pre-cooling pipeline and is arranged above an inner tank of the low-temperature normal-pressure storage tank. Low-temperature propane / low-temperature butane gas is not received from the transport ship to carry out gas-phase precooling on the low-temperature propane / butane normal-pressure storage tank, low-temperature liquid-phase propane / low-temperature liquid-phase butane is not output by a cabin sweeping pump to carry out liquid-phase precooling on the low-temperature propane / butane normal-pressure storage tank, and precooling of the low-temperature propane / butane normal-pressure storage tank is completed before the overseas transport ship berths. The pre-cooling process is not influenced by weather, tide and other environmental factors, and operation is more stable; the outer wheel parking cost is not generated, wharfs are not involved in the pre-cooling process, dispatching and operation are limited to a reservoir area, and if emergencies are small in wave range, processing is more timely.

Description

Technical Field

[0001] The utility model relates to an alkane storage tank precooling system, belonging to the technical field of low-temperature liquefied hydrocarbon storage. Background Art

[0002] Propane and butane are the main components of liquefied petroleum gas. As a strategic reserve of urban gas energy, liquefied petroleum gas is of great significance. In order to facilitate storage and transportation, propane gas is cooled to -42°C at normal pressure to liquefy it. The volume of liquid low-temperature propane is reduced by 250 to 300 times compared with the gaseous state. Butane gas is cooled to -10°C at normal pressure to liquefy it. The volume of liquid low-temperature butane is reduced by about 270 times compared with the gaseous state. After the low-temperature propane / low-temperature butane overseas transport ship berths at the terminal, the unloading is stored in the low-temperature propane / butane low-temperature atmospheric pressure storage tank. As the core equipment of the storage area, the low-temperature propane / butane low-temperature atmospheric pressure storage tank has a large tank capacity, large investment, and high construction difficulty. It must be pre-cooled before production. The pre-cooling effect is related to whether the storage area can operate smoothly. The propane temperature in the transport ship is about -42℃, and the butane temperature is about -10℃. Precooling the storage tank before it is put into operation can prevent the temperature of low-temperature propane / low-temperature butane from changing too quickly when it enters the storage tank directly. The storage tank will generate stress due to the sudden low temperature, resulting in cold brittle phenomena such as tearing of the weld and cracking of the tank body.

[0003] The prior art precooling of cryogenic propane / butane cryogenic atmospheric pressure storage tanks is divided into the following steps: the first step is gas phase replacement precooling. The ship's gasifier is used to gasify the cryogenic propane / cryogenic butane, and the cryogenic propane / butane gas phase first enters the corresponding gas phase pipeline through the gas phase arm, and then enters the corresponding cryogenic tank for replacement precooling. The second step is liquid phase precooling and filling. The cryogenic propane / cryogenic butane enters the corresponding unloading pipeline through the unloading arm by the sweeping pump, and is transported to the corresponding cryogenic tank for precooling and filling.

[0004] The above technology has the following problems:

[0005] 1. Due to the large volume of low-temperature and normal-pressure storage tanks, the long pre-cooling time, and the uncertainty of whether the pre-cooling operation can be carried out smoothly when the ship is docked at the port, affected by factors such as weather and tides. These factors will increase the berthing costs of foreign ships.

[0006] 2. Using the auxiliary facilities of the transport ship to gasify the low-temperature propane / low-temperature butane will consume energy and increase the pre-cooling cost.

[0007] 3. It is not conducive to the growth of the enterprise’s economic benefits.

[0008] 4. The pre-cooling process involves the scheduling and operation of the dock and storage area, with a wide operating area, many uncontrollable factors and many safety hazards. Utility Model Content

[0009] The utility model aims to provide an alkane storage tank precooling system to solve the above-mentioned problems.

[0010] The technical solution adopted by the utility model is as follows:

[0011] A precooling system for an alkane storage tank comprises a normal temperature pressure storage tank and a low temperature and normal pressure storage tank connected by a delivery pipeline, wherein the delivery pipeline leads from the normal temperature and pressure storage tank to the low temperature and normal pressure storage tank, a reduced pressure flash device is arranged on the delivery pipeline, and a nozzle is arranged at the output port of the delivery pipeline, and the nozzle is arranged above the inner tank of the low temperature and normal pressure storage tank.

[0012] Optionally, the delivery pipeline includes a normal temperature pipeline and a precooling pipeline that are connected, the normal temperature pipeline is arranged upstream of the precooling pipeline, and the reduced pressure flash evaporation device and the nozzle are arranged on the precooling pipeline.

[0013] Optionally, a delivery pump is provided on the normal temperature pipeline.

[0014] Optionally, the nozzle comprises a plurality of nozzles.

[0015] Optionally, a precooling loop is provided between the output port of the delivery pipeline and the nozzle, and the precooling loop is provided above the inner tank of the low-temperature and normal-pressure storage tank.

[0016] Optionally, the reduced pressure flash device is a pressure reducing valve.

[0017] Optionally, a flow meter is provided upstream of the precooling pressure reducing valve.

[0018] Optionally, a pressure gauge is provided downstream of the precooling pressure reducing valve.

[0019] Optionally, the normal temperature pressure storage tank is a spherical tank.

[0020] Optionally, the low-temperature and normal-pressure storage tank is made of carbon steel.

[0021] In summary, due to the adoption of the above technical solution, the beneficial effects of the utility model are:

[0022] 1. The utility model provides an alkane storage tank precooling system, which does not receive cryogenic propane / cryogenic butane gas from a transport ship to precool the cryogenic propane / butane cryogenic atmospheric pressure storage tank in gas phase, nor uses a cabin sweeping pump to output cryogenic liquid propane / cryogenic liquid butane to precool the cryogenic propane / butane cryogenic atmospheric pressure storage tank in liquid phase. The precooling of the cryogenic propane / butane cryogenic atmospheric pressure storage tank is completed before the overseas transport ship berths, and the precooling process is not affected by environmental factors such as weather and tides, so the operation is more stable; no foreign ship berthing fees are incurred, the precooling process does not involve the dock, and the dispatching and operation are limited to the storage area. If there is an emergency, the scope of impact is small and the handling is more timely.

[0023] 2. The utility model provides an alkane storage tank precooling system, which uses liquid propane / butane at room temperature for precooling, does not add additional facilities, does not consume additional energy, saves investment and precooling costs, and is conducive to improving the economic benefits of the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of this scheme without a delivery pump.

[0025] Figure 2 This is a schematic diagram of the structure of the propane with delivery pump in this scheme.

[0026] Figure 3 This is a schematic diagram of the structure of the butane delivery pump in this scheme.

[0027] Markings in the figure: 1-normal temperature pressure storage tank, 2-normal temperature pipeline, 3-precooling pipeline, 4-flow meter, 5-pressure reducing valve, 6-pressure gauge, 7-precooling loop pipe, 8-low temperature normal pressure storage tank, 9-nozzle, 10-delivery pump. DETAILED DESCRIPTION

[0028] The utility model is described in detail below in conjunction with the accompanying drawings.

[0029] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0030] A precooling system for an alkane storage tank, such as Figure 1-3 As shown, it includes a normal temperature pressure storage tank 1 and a low temperature and normal pressure storage tank 8 connected by a transmission pipeline, the transmission pipeline leads from the normal temperature and pressure storage tank 1 to the low temperature and normal pressure storage tank 8, a reduced pressure flash device is provided on the transmission pipeline, and a nozzle 9 is provided at the output port of the transmission pipeline, and the nozzle 9 is arranged above the inner tank of the low temperature and normal pressure storage tank 8.

[0031] Specifically, the room temperature liquid phase alkane from the room temperature pressure storage tank 1 is delivered to the low temperature normal pressure storage tank 8 through a conveying pipeline, and the liquid phase alkane is subjected to a reduced pressure flash evaporation device. A part of the liquid needs to absorb energy to be converted into a gaseous state, producing a gas-liquid two-phase. At the same time, this part of energy is absorbed from the liquid itself, causing the average temperature of the liquid to drop, thus realizing a cooling process. Since both the gas and liquid phases of the alkane have been cooled, both the low temperature flash gas and the low temperature liquid phase can provide a cold source, the low temperature flash gas absorbs heat, and the low temperature liquid phase absorbs heat and vaporizes, thereby realizing cooling of the storage tank. The gas and liquid two-phase alkane enters the upper part of the inner tank of the low temperature normal pressure storage tank 8, and is finally evenly sprayed into the tank through the nozzle 9, absorbing heat and cooling. At the beginning of precooling, the temperature inside the tank is high. The low-temperature liquid after decompression absorbs a large amount of heat in the form of sprayed mist droplets. It evaporates and vaporizes before falling to the bottom of the tank. As the temperature inside the tank decreases, the temperature difference between the sprayed mist droplets and the tank decreases, the vaporization process slows down, and the incompletely vaporized mist droplets fall to the bottom plate, gradually completing the precooling and filling.

[0032] As another specific embodiment, the nozzles 9 include a plurality of nozzles. The plurality of nozzles 9 can cover a larger area in the low-temperature atmospheric pressure storage tank 8, thereby improving the cooling efficiency.

[0033] As another specific embodiment, a precooling loop 7 is provided between the output port of the delivery pipeline and the nozzle 9, and the precooling loop 7 is provided above the inner tank of the low-temperature atmospheric pressure storage tank 8. Through the precooling loop 7, multiple nozzles 9 can be sequentially fixed on the precooling loop 7, the nozzles 9 are transported for alkane, and the nozzles 9 are evenly arranged above the inner tank of the low-temperature atmospheric pressure storage tank 8.

[0034] As another specific embodiment, the reduced pressure flash evaporation device is a pressure reducing valve 5. When the liquid passes through the pressure reducing valve 5, it will experience a sudden drop in pressure, and due to the reduction in pressure, the boiling point of the liquid will decrease accordingly, thereby enabling the flash evaporation of liquid-phase alkanes. The pressure reducing valve 5 is positioned as close as possible to the precooling nozzle on the top of the low-temperature atmospheric pressure storage tank 8 to shorten the length of the two-phase flow pipeline after the pressure reducing valve 5, and to avoid pipeline vibration, pipeline displacement, and even damage to the storage tank caused by the two-phase flow in the long-distance pipeline.

[0035] As another specific implementation, a flow meter 4 is provided upstream of the pressure reducing valve 5. It can be used to measure the precooling flow of the liquid phase normal temperature alkane. Specifically, the flow meter 4 is close to the pressure reducing valve 5 and is provided at the liquid pipeline rather than the two-phase flow, which can ensure the accuracy of flow detection.

[0036] As another specific embodiment, a pressure gauge 6 is provided downstream of the pressure reducing valve 5. The pressure gauge 6 can be used to monitor the pressure of the liquid alkane in the transport pipeline after the pressure is reduced to ensure the effect of flash evaporation.

[0037] As another specific embodiment, the normal temperature pressure storage tank 1 is a spherical tank. The spherical tank has good pressure resistance, shock resistance, explosion resistance and other properties, and can ensure the safety of alkane storage.

[0038] As another specific embodiment, the delivery pipeline includes a normal temperature pipeline 2 and a precooling pipeline 3 which are connected. The normal temperature pipeline 2 is arranged upstream of the precooling pipeline 3, and the reduced pressure flash evaporation device and the nozzle 9 are arranged on the precooling pipeline 3. Since the alkane is cooled after passing through the pressure reducing valve 5, the pipeline provided by the pressure reducing valve 5 and the downstream pipeline are the precooling pipeline 3, and the normal temperature pipeline 2 can be used before the pressure reducing valve 5. In particular, for the transportation of propane, the low temperature resistance requirement of the precooling pipeline 3 is better than that of the normal temperature pipeline 2, and the specific minimum low temperature resistance is -45°C.

[0039] As another specific implementation, Figure 2 , 3 As shown, a delivery pump 10 is provided on the normal temperature pipeline 2. Specifically, the vapor pressure of butane itself is relatively low and cannot overcome the hydraulic column between the spherical tank and the low temperature storage tank. The delivery pump 10 can pressurize the liquid phase normal temperature butane stored in the existing butane spherical tank, and at the same time, the butane can be delivered externally. In the case where propane needs to be delivered externally, a delivery pump 10 can also be provided, but the vapor pressure of propane itself is relatively high and can overcome the hydraulic column between the spherical tank and the low temperature storage tank. The interface between the delivery pipeline and the low temperature and normal pressure storage tank 8 can be provided upstream of the delivery pump 10 without pressurizing the propane.

[0040] As another specific embodiment, the material of the low-temperature atmospheric pressure storage tank 8 is carbon steel. Carbon steel is a metal material with relatively high hardness and strength, and is suitable for manufacturing workpieces and devices that need to withstand high pressure, high temperature, high strength, etc., and is adapted to the low-temperature characteristics of stored liquids such as propane and butane. Specifically, the propane low-temperature atmospheric pressure storage tank 8 is made of low-temperature carbon steel, which can withstand a minimum low temperature of -45°C. The butane low-temperature atmospheric pressure storage tank 8 is made of ordinary carbon steel, which can withstand a minimum low temperature of -20°C.

[0041] The working process of the alkane storage tank precooling system provided in this embodiment is as follows:

[0042] For propane: Figure 1 , 2 As shown, liquid-phase room-temperature propane from a propane spherical tank reaches the top of a propane low-temperature and normal-pressure storage tank 8 through a normal-temperature pipeline 2 and a precooling pipeline 3, and after being reduced in pressure by a pressure reducing valve 5, enters a precooling loop pipe 7 below the ceiling of the top of the propane low-temperature and normal-pressure storage tank 8, and is evenly sprayed into the tank through a nozzle 9 to precool the storage tank. The flow meter 4 takes the flow upstream of the pressure reducing valve 5 to control the pressure reducing valve 5, closes the pressure reducing valve 5 when the flow decreases, and opens the pressure reducing valve 5 when the flow increases, so as to maintain the flow stable, thereby effectively controlling the precooling rate of the propane low-temperature and normal-pressure storage tank 8.

[0043] For butane: Figure 3 As shown, liquid-phase room-temperature butane from the butane spherical tank enters the room-temperature pipeline 2, is first pressurized by the delivery pump 10, and then enters the room-temperature pipeline 2 and the precooling pipeline 3, reaches the top of the butane low-temperature and normal-pressure storage tank 8, and then is depressurized by the pressure reducing valve 5, and enters the precooling ring pipe 7 below the ceiling of the top of the butane low-temperature and normal-pressure storage tank 8, and finally is evenly sprayed into the tank through the nozzle 9 to cool the storage tank. The flow meter 4 takes the upstream flow of the pressure reducing valve 5 to control the pressure reducing valve 5. When the flow rate decreases, the pressure reducing valve 5 is closed, and when the flow rate increases, the pressure reducing valve 5 is opened to maintain the flow rate stable, thereby effectively controlling the precooling rate of the butane low-temperature and normal-pressure storage tank 8.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The present invention is extended to any new features or any new combination disclosed in this specification, and any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

[0045] In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

Claims

1. An alkane storage tank precooling system, characterized in that: The invention comprises a normal temperature pressure storage tank (1) and a low temperature normal pressure storage tank (8) which are connected by a delivery pipeline, wherein the delivery pipeline leads from the normal temperature pressure storage tank (1) to the low temperature normal pressure storage tank (8), the delivery pipeline is provided with a reduced pressure flash evaporation device, and the output port of the delivery pipeline is provided with a nozzle (9), and the nozzle (9) is arranged above the inner tank of the low temperature normal pressure storage tank (8).

2. The alkane storage tank precooling system according to claim 1, characterized in that: The transport pipeline comprises a normal temperature pipeline (2) and a precooling pipeline (3) which are connected to each other. The normal temperature pipeline (2) is arranged upstream of the precooling pipeline (3), and the reduced pressure flash evaporation device and the nozzle (9) are arranged on the precooling pipeline (3).

3. The alkane storage tank precooling system according to claim 2, characterized in that: The normal temperature pipeline (2) is provided with a delivery pump (10).

4. The alkane storage tank precooling system according to claim 1, characterized in that: The nozzle (9) comprises a plurality of nozzles.

5. The alkane storage tank precooling system according to claim 4, characterized in that: A precooling loop pipe (7) is provided between the output port of the delivery pipeline and the nozzle (9), and the precooling loop pipe (7) is provided above the inner tank of the low-temperature and normal-pressure storage tank (8).

6. The alkane storage tank precooling system according to claim 1, characterized in that: The reduced pressure flash evaporation device is a pressure reducing valve (5).

7. The alkane storage tank precooling system according to claim 6, characterized in that: A flow meter (4) is provided upstream of the pressure reducing valve (5).

8. The alkane storage tank precooling system according to claim 6, characterized in that: A pressure gauge (6) is provided downstream of the pressure reducing valve (5).

9. The alkane storage tank precooling system according to claim 1, characterized in that: The normal temperature pressure storage tank (1) is a spherical tank.

10. The alkane storage tank precooling system according to claim 1, characterized in that: The material of the low-temperature and normal-pressure storage tank (8) is carbon steel.

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