CN202420026U - Natural gas system and energy recovery device of natural gas system - Google Patents

Abstract

The utility model discloses a natural gas system and an energy recovery device of the natural gas system. The natural gas system comprises a refrigerating fluid heat exchange device and a refrigeration house, wherein the refrigerating fluid heat exchange device is used for heating input natural gas, and then supplying the heated natural gas to a natural gas pipe network; and the refrigeration house is connected with the refrigerating fluid heat exchange device, and is used for storing refrigerants and transmitting the refrigerants to the refrigerating fluid heat exchange device through an inlet pipe. The refrigerating fluid heat exchange device is further connected with the refrigeration house through a backflow pipe; the refrigerants are transmitted back to the refrigeration house through the backflow pipe after being cooled by the refrigerating fluid heat exchange device. According to the utility model, a LNG (Liquefied Natural Gas) pipeline part and a CNG (Compressed Natural Gas) pipeline part are respectively provided with a refrigerating fluid heat exchange device, the cold energy generated in the heat exchange process of the natural gas can be transmitted to the refrigerants flowing in the refrigerating fluid heat exchange devices, and the refrigerated refrigerants can be transmitted back to the refrigeration house, so that the cold energy in the natural gas system can be efficiently utilized so as to save the energy.

Description

Natural gas system and natural gas system energy recovery device

technical field

The utility model relates to the field of natural gas systems, and in particular relates to an energy recovery device for natural gas systems.

Background technique

Liquefied Natural Gas (LNG for short) station, Compressed Natural Gas (CNG for short) station, and L-CNG station are commonly used systems at present, as shown in Figure 1, L-CNG in related technologies The station adopts the parallel process of LNG and CNG to supply gas to the pipeline network. The LNG tanker fills the LNG storage tank 1 with LNG, and then the LNG storage tank 1 enters the liquefied natural gas 9 into the supercharger 2, and after the liquefied natural gas 9 is cut off, the LNG is vaporized and boosted in the supercharger 2, Afterwards, the gasified natural gas flow 10 is injected back into the upper part of the LNG storage tank 1 as a pressure source for the LNG storage tank 1 to supply to the outside. The LNG storage tank 1 produces an output liquefied natural gas 11 under the action of the gas phase pressure and transports it to the gasifier 3 , and the gasifier 3 produces an output liquefied natural gas 12 which is supplied to the gas pipeline network 4 . On the other hand, the CNG tanker directly supplies the compressed natural gas 13 into the gas pressure regulating chamber 6, and after depressurization, the output natural gas 14 is supplied to the NG-refrigerated liquid heat exchanger 5, and the output natural gas 15 is supplied to the Gas pipeline network4. The gas boiler gas 18 provided from the gas pipeline network 4 is sent to the gas boiler 7, the hot water 16 generated by combustion enters the NG-coolant heat exchanger 5, and the cooled water 17 returns to the gas boiler 7.

It can be seen that although the current L-CNG station adopts cold energy utilization, most of the specific methods use the cold energy utilization mode of circulating medium to take cold and then supply cold storage or directly supply cooling to buildings in summer. However, the current scheme of energy recovery and utilization is not comprehensive, and a lot of energy is wasted.

Aiming at the problem of energy waste caused by incomplete energy recovery and utilization of natural gas systems in related technologies, no effective solution has been proposed so far.

Utility model content

Aiming at the problems in related technologies, the utility model proposes a natural gas system and a natural gas system energy recovery device, which can realize effective recovery and utilization of cold energy in the LNG pipeline part and CNG pipeline part, and save the energy of the natural gas system.

The technical scheme of the utility model is achieved in that:

According to one aspect of the utility model, a natural gas system is provided.

The natural gas system according to the utility model includes: a refrigerated liquid heat exchange device for heating the input natural gas and supplying the heated natural gas to the gas pipeline network; a cold storage connected to the refrigerated liquid heat exchange device for storing refrigerant , and the refrigerant is input to the refrigerant heat exchange device through the input pipe; wherein, the refrigerant heat exchange device is further connected to the cold storage through the return pipe, and the refrigerant is looped back to the refrigerator through the return pipe after the refrigerant is cooled by the refrigerant heat exchange device. cold storage.

Wherein, the refrigerant heat exchange device includes a first refrigerant heat exchanger and a second refrigerant heat exchanger, and the cold storage divides the refrigerant through the respective input pipes of the first refrigerant heat exchanger and the second refrigerant heat exchanger. Provided to the first refrigerant heat exchanger and the second refrigerant heat exchanger; wherein, the first refrigerant heat exchanger is used to vaporize the liquefied natural gas, and input the gasified natural gas to the gas pipeline network; The second refrigerant heat exchanger is used to receive compressed natural gas, heat up the received compressed natural gas, and input the heated natural gas to the gas pipeline network; and, both the first refrigerant heat exchanger and the second refrigerant heat exchanger are It is connected to the cold storage through the return pipe, and the refrigerant is looped back to the cold storage through the return pipe after the refrigerant is cooled by the first refrigerant heat exchanger and the second refrigerant heat exchanger.

The system may further include: a liquefied natural gas storage tank, used to output liquefied natural gas; a supercharger, used to pressurize the liquefied natural gas stored in the liquefied natural gas storage tank; The compressed liquefied natural gas is sent to the first refrigerant heat exchanger.

The system may further include: a gasifier, connected in parallel with the first refrigerant heat exchanger, used to process the pressurized liquefied natural gas from the liquefied natural gas storage tank and then input it into the gas Pipe Network.

In addition, the system may further include: an expander, configured to use the expansion of the input compressed natural gas to generate electricity, and output the decompressed natural gas to the second refrigerant liquid heat exchanger.

The system may further include: a low-temperature heat exchanger and a third refrigerant heat exchanger, connected in series between the second refrigerant heat exchanger and the gas pipeline network; wherein, the low-temperature heat exchanger receives the second refrigerant heat exchanger The heated natural gas output by the heat exchanger, the low-temperature heat exchanger has a water heating system, which is used to heat up the natural gas from the second refrigerant heat exchanger; the third refrigerant heat exchanger is used to receive the output of the low-temperature heat exchanger The heated natural gas is connected to the boiler with the third refrigerated liquid heat exchanger, which is used to heat up the natural gas from the low-temperature heat exchanger through boiler water, and input the heated natural gas to the gas pipeline network.

In addition, the cold storage is further provided with a circulating pump, which is used to input the refrigerant in the cold storage to the refrigerant heat exchange device through the input pipe;

Optionally, the refrigerant is an aqueous solution of ethylene glycol.

According to another aspect of the utility model, an energy recovery device for a natural gas system is provided. According to the utility model, the natural gas system energy recovery device includes a cold store and a refrigerant heat exchange device. The cold store is connected to the refrigerant heat exchange device through an input pipe and a return pipe; The heating device, and receives the refrigerant returned by the cooling liquid heat exchange device through the return pipe after being cooled by the cooling liquid heat exchange device, wherein the cooling liquid heat exchange device is used to heat the input natural gas.

Wherein, the refrigerating liquid heat exchange device includes a first refrigerating liquid heat exchanger and a second refrigerating liquid heat exchanger. The input pipe is provided to the first refrigerant heat exchanger and the second refrigerant heat exchanger; among them, the first refrigerant heat exchanger is used to vaporize the liquefied natural gas, and the gasified natural gas is input to the gas pipe network; the second refrigerated liquid heat exchanger is used to receive compressed natural gas, heat up the received compressed natural gas, and input the heated natural gas to the gas pipeline network; and, the first refrigerated liquid heat exchanger exchanges heat with the second refrigerated liquid The refrigerators are connected to the cold storage through their respective return pipes, and the refrigerant is looped back to the cold storage through the return pipes after the refrigerant is cooled by the first refrigerant heat exchanger and the second refrigerant heat exchanger.

The device may further include: an expander, configured to use the expansion of the input compressed natural gas to generate electricity, and output the decompressed natural gas to the second refrigerant liquid heat exchanger.

The device may further include: a low-temperature heat exchanger and a third refrigerant heat exchanger, connected in series between the second refrigerant heat exchanger and the gas pipeline network; wherein, the low-temperature heat exchanger receives the second refrigerant heat exchange The low temperature heat exchanger has a water heating system, which is used to heat up the natural gas from the second refrigerant heat exchanger; the third refrigerant heat exchanger is used to receive the temperature increase output by the low temperature heat exchanger After the natural gas, the third refrigerant heat exchanger is connected to the boiler, which is used to raise the temperature of the natural gas from the low-temperature heat exchanger through the boiler water, and input the heated natural gas to the gas pipeline network.

In addition, the cold storage is further provided with a circulating pump, and the circulating pump is used to input the refrigerant in the cold storage to the cooling liquid heat exchange device through the input pipe.

The utility model can transfer the cold energy generated in the heat exchange process of natural gas to the refrigerant flowing in the refrigerant heat exchanger by arranging the refrigerant heat exchanger in the LNG pipeline part and the CNG pipeline part, and transfer the cooled refrigerant Loop back to the cold storage, thus effectively utilizing the cold energy in the natural gas system and saving energy.

Description of drawings

Fig. 1 is a block diagram of a natural gas system in the related art;

Fig. 2 is a block diagram of a natural gas system according to an embodiment of the present invention.

Detailed ways

The cold energy of conventional liquefied natural gas (LNG), compressed natural gas (CNG) or L-CNG stations cannot be effectively utilized, and the natural gas that meets the requirements is directly entered into the pipeline network NG, and in the process of natural gas processing, After LNG is gasified or CNG is decompressed, a heater needs to be installed to heat NG to about 10°C. The fuel used by the heater is generally pipeline gas, and the pressure energy of CNG has not been fully utilized. Therefore, not only the cold energy of LNG and CNG is not used, but also the unused cold energy needs to be supplemented by burning NG so that NG can reach the standard of entering the pipeline network; in addition, the pressure energy of CNG is also wasted.

Aiming at the above problems, the utility model proposes a solution, and the specific embodiments of the utility model will be described in detail below.

According to an embodiment of the utility model, a natural gas system and an energy recovery device for the natural gas system are provided.

As shown in Figure 2, the natural gas system and the energy recovery device therein according to the embodiment of the utility model include:

The supercharger 22 is used to pressurize the liquefied natural gas stored in the liquefied natural gas storage tank 21;

The liquefied natural gas storage tank 21 is used to output the pressurized liquefied natural gas 217;

The first refrigerant heat exchanger 28 is used to gasify the input pressurized liquefied natural gas 219, and input the gasified natural gas 220 to the gas pipeline network 24;

The second refrigerant heat exchanger 27 is used to receive compressed natural gas 224, heat up the received compressed natural gas 224, and input the heated natural gas 227 to the gas pipeline network 24;

Cold storage 210, used for storing refrigerant;

The circulation pump 211 is connected to the cold storage 210, and is used to divide the refrigerant in the cold storage 210 and then input it to the first cooling liquid heat exchanger 28 and the second cooling liquid heat exchanger 27 through the input pipe;

Wherein, the first cooling liquid heat exchanger 28 and the second cooling liquid heat exchanger 27 are further connected to the cold storage through the return pipe, and the cooling medium is cooled by the first cooling liquid heat exchanger 28 and the second cooling liquid heat exchanger 27 Afterwards, the refrigerant is looped back to the cold storage 210 through the return pipe.

Additionally, the device may further include:

The vaporizer 23 is connected in parallel with the first refrigerant heat exchanger 28, and is used to process the pressurized liquefied natural gas 218 from the liquefied natural gas storage tank 21 and then input it to the gas pipeline network in case of abnormal working conditions twenty four.

In addition, the natural gas system energy recovery device may further include:

The expander 212 is configured to use the expansion of the input compressed natural gas 223 to generate electricity 228 , and output the decompressed natural gas 224 to the second refrigerant liquid heat exchanger 27 .

In addition, the natural gas system energy recovery device may further include:

The low-temperature heat exchanger 26 and the third refrigerant heat exchanger 25 are connected in series between the second refrigerant heat exchanger 27 and the gas pipeline network 24;

Wherein, the low-temperature heat exchanger 26 receives the heated natural gas 225 output by the second refrigerant heat exchanger 27, and the low-temperature heat exchanger 26 has a water heating system, which is used to carry out natural gas from the second refrigerant heat exchanger 27. heat up;

The third refrigerant heat exchanger 25 is used to receive the heated natural gas 226 output by the low-temperature heat exchanger 26, and the third refrigerant heat exchanger 25 is connected to the boiler 213 for exchanging heat from the low-temperature heat through the boiler water 235. The heated natural gas 226 of the device 26 is heated, and the heated natural gas 227 is input to the gas pipeline network 24, and the boiler water 236 is returned to the boiler 213.

Wherein, the above-mentioned refrigerant can be an aqueous solution of ethylene glycol. In addition, the utility model can also adopt other refrigerants, which will not be listed here.

In practical application, the LNG tanker can be used to fill the LNG 214 (1.5 bar, -162°C) into the LNG storage tank 21, and then the LNG storage tank 21 generates the output LNG 215 and fills part of it into the supercharger 22 LNG, after the output liquefied natural gas 215 is cut off, the LNG is gasified and boosted to 4bar in the supercharger 22, and then the output liquefied natural gas 216 is produced and injected back to the top of the liquefied natural gas storage tank 21, as the liquefied natural gas storage tank 21 goes out source of stress. The liquefied natural gas storage tank 21 produces the output liquefied natural gas 217 under the action of the gas phase pressure, with a flow rate of 1500kg/h, which is split into two output liquefied natural gas 218 and liquefied natural gas 219. Under normal working conditions, the diverted liquefied natural gas 218 can be unavailable. It is used only in failure or maintenance conditions. The output liquefied natural gas 219 is sent to the first refrigerant heat exchanger 28, and the gasified NG 220 is directly fed into the gas pipeline network 24 with a pressure of 4 bar.

On the other hand, the CNG tanker feeds natural gas (CNG) 221 with a flow rate of 7150kg/h, a temperature of 20°C, and a pressure of 220bar. It is divided into two separate flows, CNG 222 and CNG 223, and then enters the gas surge chamber 29 respectively. and the expander 212, the gas surge chamber 29 may not be used under normal working conditions, and it is only used under fault or overhaul conditions; CNG expands in the expander 212 to generate 200kW electric energy output 228, after decompression The NG 224 is 4bar, the temperature is -158°C, enters the second refrigerant liquid heat exchanger 27, and heats up to -30°C, the second refrigerant liquid heat exchanger 27 produces output natural gas 225 and provides it to the low temperature heat exchanger 26, After the temperature of the low-temperature heat exchanger 26 is raised to -10°C, the output natural gas 226 is generated and sent to the third refrigerant heat exchanger 25, and the third refrigerant heat exchanger 25 generates the output natural gas 227 after the temperature reaches 10°C, and provides To the gas pipeline network 24.

Optionally, the refrigerant drawn from the cold storage 210 is an aqueous solution of ethylene glycol, with a flow rate of 100t/h and a temperature of -10°C. It enters the circulation pump 211 (refrigerant liquid circulation pump) through the refrigerant flow 229 to pressurize and split into The two refrigerant flows 230 and 231 respectively enter the second refrigerant heat exchanger 27 and the first refrigerant heat exchanger 28 to absorb the cooling capacity of CNG and LNG, and then merge into the refrigerant flow 232. The refrigerant temperature at this time is -14 °C, return to the cold storage 210. The low-temperature hot water 233 from the outside enters the low-temperature heat exchanger 26 at a flow rate of 10 t/h and a temperature of 40°C; the released water flow 234 returns to the heat source with a return temperature of 25°C. The gas flow 237 drawn from the gas pipe network 24 is supplied to the boiler 213, the hot water 235 generated by combustion enters the third refrigerant heat exchanger 25, and the cooled water flow 236 returns to the boiler 213. This part of the process can be configured as a backup.

Since the system adds the first and second refrigerant heat exchangers, most of the cooling capacity of LNG and CNG can be recovered and applied to the cold storage 210, and the added low-temperature heat exchanger 26 can use waste heat to ensure that gas enters the gas pipeline network 24 Combined with several measures, the annual gas consumption of gas-fired boilers can be greatly reduced by 184,000 m3 on the premise of creating a large amount of cooling energy, which will bring significant benefits of increasing income and reducing expenses.

It can be seen that with the help of the above-mentioned system, aiming at the defects of the existing technical solutions, the LNG-refrigerant heat exchanger and the CNG-refrigerant heat exchanger are respectively installed to realize the utilization of LNG and CNG cold energy, and reduce the heating of the above-mentioned gas by the gas boiler. At the same time, the NG-low temperature refrigerant heat exchanger is also installed to make full use of the external waste heat to further reduce the gas consumption of the gas boiler; in addition, by setting the expander, the safety of the pressure energy can be further realized on the basis of realizing the recovery of the cold energy of the system Recovery, so that the pressure of CNG can be recovered and generate considerable electricity, while also generating more cold energy, which is used in cold storage, creating economic benefits.

Wherein, only one cold store 210 is shown in the drawing, and in actual application, there may be multiple cold stores to provide refrigerant for the first and second refrigerant liquid heat exchangers respectively.

Referring to the energy recovery device for the natural gas system of the present utility model shown in Fig. 2, when taking LNG with a pressure of 1 standard atmosphere, a temperature of -162°C, and a flow rate of 15,000 kg/h as an example, the first refrigerant heat exchanger 28 generates The cold capacity produced by the second refrigerant liquid heat exchanger 27 is 214.3 kW. When taking CNG with a pressure of 220 standard atmospheres, a temperature of 20° C., and a flow rate of 10,000 Nm3/h as an example, the generating power of the expander 212 is 538 kW, and the cooling capacity generated by the second refrigerant heat exchanger 27 is 823 kW.

To sum up, with the help of the above-mentioned technical solution of the present utility model, by setting refrigerant heat exchangers in the LNG pipeline part and the CNG pipeline part, the cold energy generated during the heat exchange process of natural gas can be transferred to the refrigerant liquid for heat exchange The refrigerant flowing in the device, and the cooled refrigerant is looped back to the cold storage, thereby effectively utilizing the cold energy in the natural gas system, realizing the external supply of cold energy, effectively saving energy, and greatly reducing the gas-fired boiler due to heating LNG and CNG. The resulting gas consumption, and the pressure of CNG can be recovered by the expander to generate electricity, further saving energy.

The above descriptions are only preferred embodiments of the present utility model, and are not intended to limit the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present utility model shall be included in the Within the protection scope of the present utility model.

Claims (13)

1. a natural gas system is characterized in that, comprising:

The freezing liquid heat-exchanger rig be used for the natural gas of input is heated, and the natural gas after will heating provides to gas ductwork;

Freezer is connected to said freezing liquid heat-exchanger rig, is used to store refrigerant, and refrigerant is inputed to said freezing liquid heat-exchanger rig through input pipe;

Wherein, said freezing liquid heat-exchanger rig further is connected to said freezer through return duct, after by said freezing liquid heat-exchanger rig refrigerant being lowered the temperature, passes through return duct with refrigerant loopback to said freezer.

2. natural gas system according to claim 1; It is characterized in that; Said freezing liquid heat-exchanger rig comprises the first freezing liquid heat exchanger and the second freezing liquid heat exchanger, and said freezer is shunted the back with refrigerant and provided to said first freezing liquid heat exchanger and the said second freezing liquid heat exchanger through said first freezing liquid heat exchanger and said second freezing liquid heat exchanger input pipe separately;

Wherein, the said first freezing liquid heat exchanger is used for gasifying from liquefied natural gas, and the natural gas that will obtain after will gasifying inputs to gas ductwork;

The said second freezing liquid heat exchanger is used to receive compressed natural gas, and the compressed natural gas that receives is heated up, and the natural gas that heats up is inputed to gas ductwork;

And; Said first freezing liquid heat exchanger and the said second freezing liquid heat exchanger all are connected to said freezer through return duct, after by said first freezing liquid heat exchanger and the said second freezing liquid heat exchanger refrigerant being lowered the temperature, pass through return duct with refrigerant loopback to said freezer.

3. natural gas system according to claim 2 is characterized in that, further comprises:

LNG tank is used to export liquefied natural gas;

Booster is used for the liquefied natural gas of LNG tank storage is carried out supercharging;

Wherein, said LNG tank is used to export through the liquefied natural gas after the said booster supercharging to the said first freezing liquid heat exchanger.

4. natural gas system according to claim 2 is characterized in that, further comprises:

Gasifier, parallelly connected with the said first freezing liquid heat exchanger, be used for occurring after handling, inputing to said gas ductwork under the unusual situation from the liquefied natural gas after the supercharging of said LNG tank in operating mode.

5. natural gas system according to claim 2 is characterized in that, further comprises:

Decompressor is used to utilize the expansion acting of the said compressed natural gas of input to produce electric energy, and exports post-decompression natural gas to the said second freezing liquid heat exchanger.

6. natural gas system according to claim 2 is characterized in that, further comprises:

Low-temperature heat heat exchanger and the 3rd freezing liquid heat exchanger are connected between said second freezing liquid heat exchanger and the said gas ductwork;

Wherein, said low-temperature heat heat exchanger receives the natural gas after the intensification of said second freezing liquid heat exchanger output, and said low-temperature heat heat exchanger has water-heating system, is used for the natural gas from the said second freezing liquid heat exchanger is heated up;

Said the 3rd freezing liquid heat exchanger is used to receive the natural gas after the intensification of said low-temperature heat heat exchanger output; Said the 3rd freezing liquid heat exchanger is connected with boiler; Be used for the natural gas from said low-temperature heat heat exchanger being heated up, and the natural gas after will heating up inputs to said gas ductwork through boiler water.

7. natural gas system according to claim 1 is characterized in that said freezer further is provided with circulating pump, and said circulating pump is used for the refrigerant of said freezer is inputed to said freezing liquid heat-exchanger rig through input pipe.

8. according to each described natural gas system in the claim 1 to 7, it is characterized in that said refrigerant is the aqueous solution of ethylene glycol.

9. a natural gas system energy source recovery apparatus is characterized in that, comprises freezer, freezing liquid heat-exchanger rig, and said freezer is connected with said freezing liquid heat-exchanger rig with return duct through input pipe;

Said freezer is used to store refrigerant; Through input pipe refrigerant is offered said freezing liquid heat-exchanger rig; And receive the refrigerant after the said freezing liquid heat-exchanger rig cooling of the process of returning by said freezing liquid heat-exchanger rig through return duct; Wherein, said freezing liquid heat-exchanger rig is used for the natural gas of input is heated.

10. natural gas system energy source recovery apparatus according to claim 9; It is characterized in that; Said freezing liquid heat-exchanger rig comprises the first freezing liquid heat exchanger and the second freezing liquid heat exchanger, and said freezer is shunted the back with the refrigerant of storage and provided to said first freezing liquid heat exchanger and the said second freezing liquid heat exchanger through said first freezing liquid heat exchanger and said second freezing liquid heat exchanger input pipe separately;

Wherein, the said first freezing liquid heat exchanger is used for gasifying from liquefied natural gas, and the natural gas that will obtain after will gasifying inputs to gas ductwork;

The said second freezing liquid heat exchanger is used to receive compressed natural gas, and the compressed natural gas that receives is heated up, and the natural gas that heats up is inputed to gas ductwork;

And; Said first freezing liquid heat exchanger and the said second freezing liquid the heat exchanger all return duct through separately are connected to said freezer, by the said first freezing liquid heat exchanger and the said second freezing liquid heat exchanger to refrigerant lowering the temperature the back through return duct with refrigerant loopback to said freezer.

11. natural gas system energy source recovery apparatus according to claim 10 is characterized in that, further comprises:

Decompressor is used to utilize the expansion acting of the said compressed natural gas of input to produce electric energy, and exports post-decompression natural gas to the said second freezing liquid heat exchanger.

12. natural gas system energy source recovery apparatus according to claim 10 is characterized in that, further comprises:

Low-temperature heat heat exchanger and the 3rd freezing liquid heat exchanger are connected between said second freezing liquid heat exchanger and the said gas ductwork;

Wherein, said low-temperature heat heat exchanger receives the natural gas after the intensification of said second freezing liquid heat exchanger output, and said low-temperature heat heat exchanger has water-heating system, is used for the natural gas from the said second freezing liquid heat exchanger is heated up;

Said the 3rd freezing liquid heat exchanger is used to receive the natural gas after the intensification of said low-temperature heat heat exchanger output; Said the 3rd freezing liquid heat exchanger is connected with boiler; Be used for the natural gas from said low-temperature heat heat exchanger being heated up, and the natural gas after will heating up inputs to said gas ductwork through boiler water.

13. natural gas system energy source recovery apparatus according to claim 9 is characterized in that said freezer further is provided with circulating pump, said circulating pump is used for the refrigerant of said freezer is inputed to said freezing liquid heat-exchanger rig through input pipe.

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