RU2669222C1 - Mobile compressor unit for pumping liquids of liquefied natural gas - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to the field of auxiliary compressor equipment for the transport of liquefied natural gas, namely to piston compressors that ensure the evacuation of residual low-temperature vapors of liquefied natural gas from transport or stationary containers of liquefied natural gas. Mobile compressor unit for pumping liquefied natural gas vapor includes a piston V-shaped two-row compressor located in a transportable insulated closed container without lubrication of the cylinder-piston group. Input heat-insulated pipeline of liquefied natural gas vapor is communicated with the compressor suction cavity. Output heat-insulated pipeline is communicated with the compressor discharge chamber. On the input pipeline, in front of the compressor, a pressure regulator and a buffer tank are installed in series along the motion of the medium. On the outlet pipeline, after the compressor, a buffer tank and a safety valve are installed along the path of the medium to release the high pressure of the medium onto the spark plug. On the inlet pipeline, after the pressure regulator, a shut-off remote-controlled valve is installed to allow the unit to be connected to the compressed-air purging system of the compressor with compressed nitrogen. All elements of the unit in contact with the pumped medium are made of a cold-resistant material and have thermal insulation.

EFFECT: arsenal of technical means is expanding, an efficient and convenient operation of the device is created.

8 cl, 4 dwg

Description

The present invention relates to the field of auxiliary compressor equipment for transporting liquefied natural gas, and in particular to reciprocating compressors for pumping residual low-temperature vapors of liquefied natural gas from transport or stationary containers of liquefied natural gas. In particular, the invention can be used to pump and maintain a predetermined pressure in a transport tank for transporting liquefied natural gas (hereinafter LNG).

Specific requirements for compressors and liquefied natural gas systems are:

- the ability to work on vapors of liquefied natural gas;

- use of explosion-proof equipment;

- ensuring reliable operation at temperatures of compressible medium from minus 160 ° C;

- requirements for minimum overall dimensions to ensure the possibility of transportation to the place of use;

- the requirement for the outlet pressure of 0.5-0.7 MPa to ensure that the pressure in the transport tank or storage tank is maintained;

- the requirement for thermal insulation of the compression process of the medium;

- low vibration to ensure installation in a transportable container;

- increased automation of technological processes.

To work with cryogenic media, it is necessary to use technical solutions implemented in cryogenic valves designed to operate on products whose temperature is equal to or lower than 120 K (minus 153 ° C):

- all nodes must be operational for a long time at the temperature of the cryogenic product and at ambient temperature;

- equipment should not be a significant source of heat influx to the cryogenic product;

- the design of equipment components in contact with cryogenic products must satisfy the explosion and fire safety conditions when working on these products;

- equipment components operating at cryogenic temperatures must operate without lubrication.

A known system for processing liquefied gas for a vessel, which contains a cargo tank storing liquefied natural gas (LNG), and an engine using LNG as a fuel. The liquefied gas processing system comprises: a compressor line configured to compress the vaporized gas (Boil-Off Gas or BOG) generated in the cargo tank by means of a compressor and supplying compressed BOG to the engine as fuel; a high pressure pump line configured to compress the LNG stored in the cargo tank by means of a pump and supply the compressed LNG to the engine as fuel; and a heat exchanger configured to liquefy a portion of the BOG that is compressed by the compressor by exchanging heat with the BOG that is removed from the cargo tank and transferred to the compressor (Patent Patent No. 260,8451, IPC F02B 43/00, B63H 21/14, publication December 20, 2016).

A disadvantage of the known system is its low mobility (the presence of bulky elements - a cargo tank, engine, high pressure pump and refrigerator) and the inconvenience of operation associated with the lack of a control system and remote control and the absence of a weatherproof container and the possibility of mobile transportation of the system to the place of operation for pumping residual vapors liquefied natural gas (LNG).

Known piston compressor company "SIAD Macchine Impianti" (Italy) for vapor of liquefied natural gas, working with a cryogenic environment with temperatures up to 113 K (minus 160 ° C). The compressor is mounted on a slide to facilitate installation and startup (SIAD Macchine Impianti website https://www.siadmi.com/web/siad-macchine-impianti/boil-off-gas-compressor).

A disadvantage of the known compressor is the low mobility and inconvenience of operation associated with the lack of a control system and remote control and the absence of a weatherproof container and the possibility of mobile transportation of the compressor to the place of operation for pumping residual vapors.

Known complete compressor unit for discharge and loading operations with liquefied petroleum gases (hereinafter LHG) in the GNS and AGZS projects, including a compressor unit with a 2-stage gas compressor brand 2GU 0.5-0.55 / 1.3-11 / 11-16С or ГВ 0.5 / 1.5-11См (Rdiff. = 11.0 atm) and an electric motor with a power of 11.0 kW, a control panel with pressure and temperature sensors, a liquid separator with an external level indicator, the installation frame and shut-off valve kit (Gazovik Group website https://gazovik-lpg.ru/cat/compressors/ku_2).

A disadvantage of the known complete compressor installation is that compressors and valves are used for liquefied petroleum gases, and in accordance with clause 3.1 of GOST ISO 8973-2013, liquefied petroleum gas is a gas that can be stored and / or transported in a liquid state at moderate pressure and ambient temperature. Therefore, compressors and valves for LPG do not provide the possibility of their use for vapor of liquefied natural gas (LNG), which is a cryogenic medium with a temperature of up to 113 K (minus 160 ° C).

A well-known automated compressor station located in a transportable insulated closed container and comprising a piston multi-stage high-pressure compressor with a drive (RF patent No. 135015, IPC F04B 41/00, publication 2013).

The design solution of the known compressor station does not allow it to be used for pumping vapors of liquefied natural gas.

The objective of the invention is to expand the arsenal of technical means used for pumping vapors of liquefied natural gas.

The technical result consists in the implementation of this purpose and the creation of an effective in operation and convenient to use device design used for pumping vapors of liquefied natural gas.

The indicated technical result is achieved by using a mobile compressor unit for pumping liquefied natural gas vapors, which includes a piston V-shaped double-row compressor without lubrication of the cylinder-piston group located in a transportable heat-insulated closed container, as well as an inlet heat-insulated LNG vapor pipeline communicated with the compressor suction cavity and output heat-insulated liquefied natural gas vapor pipeline in communication with the compressor cavity a. At the inlet pipe in front of the compressor, a pressure regulator and a buffer tank are installed sequentially in the direction of the medium, and a buffer tank and safety valve are installed in the outlet pipe after the compressor in the direction of the medium to discharge the increased pressure of the medium onto the candle. At the inlet pipe after the pressure regulator, a remote-controlled shut-off valve is installed to allow the unit to be connected to the compressor purge system with compressed nitrogen. All block elements in contact with the pumped medium are made of cold-resistant material and have thermal insulation.

The compressor piston group contains piston rods with piston rings made of self-lubricating material.

An electric motor is used as a compressor drive.

The inlet and outlet pipelines are connected to each other by an additional pipeline with a shut-off valve installed on it.

To control compressor pressures, pressure sensors with valve blocks are installed at the inlet and outlet pipelines.

A mobile compressor unit for pumping vapors of liquefied natural gas contains an automatic control system.

The block container consists of a technological compartment and a control compartment.

At least one compressed nitrogen cylinder of the compressor cavity purge system is located in the technological compartment of the container.

The present invention is illustrated by a specific example, which, however, is not the only possible, but clearly demonstrates the possibility of achieving the desired technical result with the above set of features.

In FIG. 1 is a schematic diagram of a mobile compressor unit for pumping vapors of liquefied natural gas; in FIG. 2 - piston compressor; in FIG. 3 - compressor unit for pumping vapors of liquefied natural gas in a container - view on plan; in FIG. 4 is the same side view.

The mobile compressor unit for pumping liquefied natural gas vapors (see Fig. 1) contains an electric drive compressor 1, an inlet heat-insulated liquefied natural gas vapor pipeline 2 connected to a cryogenic capacity of the liquefied natural gas 3, and an outlet heat-insulated liquefied natural gas vapor pipeline 3 connected to liquefied natural gas vapor collector. A pressure regulator 4 is installed sequentially in the pipeline 2 in the direction of the medium flow, a buffer tank 5 is installed at the compressor inlet, a buffer tank 6 is installed in the outlet pipe 3 after the compressor, and a safety valve 7 is used to discharge the increased gas pressure to the candle 8. For monitoring the pressure of the compressor 1 on pipelines 2 and 3 installed pressure sensors 9 and 10 with valve blocks 11 and 12. For manual discharge of vapors of liquefied natural gas from the compressor onto the spark plug valve 13 is provided. For connecting the pipe rovodov 2 and 3 is provided valve 14. To ensure the safety shut-off is provided remotely controllable valve 15 and nitrogen purge system 16 consisting of cylinders 17 with pressurized nitrogen reducer 18 and valve 19.

The compressor for compressing vapors of liquefied natural gas (Fig. 2) is a piston, V-shaped, two-row, dry (without lubrication of the piston-cylinder group) and includes an electric drive (not shown), crankcase 20, crankshaft 21, two cylinders 22, each of which valves 23 are installed, piston rod 24 with piston rings 25 made of self-lubricating material, piston rod seal 26, oil scraper 27, configured to return oil leaks to the crankcase 20 through pipelines 28 with hydraulic locks 29. Using a V-shaped double-row design The compressor function provides reduced vibration due to the balance of inertia forces and the possibility of installing the compressor in a container. The compressor also includes a lubrication system for the movement mechanism, which lubricates the crankshaft 21, bearings and movement group in the crankcase 20 and contains an oil heater 30, an oil pump 31, an oil filter 32, pressure and temperature sensors 33, a manometer 35 and a thermometer 36. On the compressor 1 placed sensors of the vibrodiagnostic system (not shown).

Pipeline 2, compressor parts in contact with the medium (cylinders 22, valves 23, piston rods 24, piston rings 25, seal 26, oil scraper 27) pipeline 3, pressure regulator 4, buffer tank 5, buffer tank 6, safety valve 7, candle 8, valve blocks 11 and 12, valves 13 and 14, valve 15 are made of cold-resistant materials.

To reduce heat influx from the environment to the pumped medium, pipeline 2, pipeline 3, pressure regulator 4, buffer tank 5, buffer tank 6, safety valve 7, taps 13 and 14, valves 15 have multilayer thermal insulation made, for example, by winding the pipeline 5-10 10 mm thick layers of airgel web (thermal insulation made of polyurethane or basalt fiber can also be used).

Mobile compressor unit is located in the container 37 (Fig. 4 and 5), divided into compartments: technological 38 and control compartment 39.

The walls of the technological compartment 38 of the container 37 are made in the form of movable curtains (not shown), so the ventilation of the technological compartment can be carried out by natural air exchange through openings located in the walls of the compartments.

Compressor 1, pipelines 1 and 2 (with equipment installed on them), a nitrogen purge system 16, and mounting kit 40 (equipment that is dismantled during transportation — electric cable, flexible hoses, etc.) are located in technological compartment 38.

In the control compartment 39 is placed an automatic control system 41, including a converter of the compressor vibration diagnostics system (not shown).

To maintain the required temperature inside the control compartment during the cold season (minimum permissible temperature 18 ° C), electric heaters (not shown) are connected electrically to the automatic control system 41 in the control compartment and can be controlled by the temperature sensor inside the container (not shown) .

To protect against fire in the container, an automatic fire alarm system 42 is provided, containing the necessary devices, sensors, detectors, sirens.

The use of a mobile compressor unit for pumping vapors of liquefied natural gas is as follows.

A mobile compressor unit for pumping liquefied natural gas vapors is transported to the place of use by a container ship (transport that provides for the possibility of transporting standard sea containers, taking into account the carrying capacity). After transportation, the unit is installed on the prepared site. Electricity is connected, as well as communications (inlet and outlet gas pipelines), which are connected via flexible connections to the source and consumer of liquefied natural gas (for example, the inlet piping to the vapor phase fitting of the cryogenic transporter, and the outlet to the fitting of the LNG filling station column).

Vapors of liquefied natural gas with temperatures from minus 160 ° C to minus 130 ° C under a small excess working pressure (not more than 0.15 MPa) enter the inlet pipe 2, from where they enter the pressure regulator 4, which provides constant pressure at the compressor inlet (for example, 0.1 MPa), after the pressure regulator 4, the LNG vapor falls into the tank 5, where the vapor of the liquefied natural gas is purified. In the tank 5, a decrease in the flow rate is provided, and its volume ensures stable operation of the compressor without flow pulsations. After the capacity of 5 pairs of LNG enter the compressor 1, where they are compressed. The compression of the LNG vapor occurs in the cylinders 22 by means of the reciprocating movement of the rod pistons 24 with the piston rings 25 of self-lubricating material. Self-lubricating material (for example, F4K20 fluoroplast or superfluvis) is used because compressor oils lose their properties at temperatures from minus 160 to minus 130 ° C. The design of the cylinders 22 minimizes heat influx from the environment to the valves and the compression zone, which leads to a minimum increase in the temperature of the medium and good cooling of the cylinders with a compressible medium. The vaporization of liquefied natural gas occurs through annular combination valves made, for example, of cold-resistant stainless steel. The reciprocating movement of the pistons is provided by a crankshaft 21, which is driven by an electric motor (not shown).

The lubrication of movement groups in the crankcase 20 (crankshaft 21, bearings) is provided by the oil system through the oil pump 31. The oil is cleaned by the oil filter 32. The oil is heated to the required temperature of about 15-50 ° C by an explosion-proof heater 30. To monitor the operation of the oil system the compressor provides sensors for monitoring pressure 33 and temperature 34, a manometer 35 and a thermometer 36.

After the compressor 1, vapors of liquefied natural gas with the necessary pressure are sent through the tank 6 to the consumer. To protect the compressor and the LNG system from increasing pressure caused by the evaporation of LNG, a safety valve 7 is provided at the compressor outlet, which relieves excess pressure on the candle. If necessary, it is possible to manually reset the candle with a tap 13.

To ensure the possibility of servicing in emergency situations during compressor abnormal operation, it is possible to disconnect the line from the compressor 1 by means of a remote-controlled valve 15 and purge the internal cavities of the compressor with inert gas — compressed dried nitrogen from the nitrogen purge system 16, through the gearbox 18 and valve 19, This opens the taps 13 and 14, and all the internal cavities of the installation are purged with nitrogen and the vapor of liquefied natural gas is discharged onto the candle.

The provided fire alarm system 42 when a fire is detected provides a fire signal to the automatic control system 41 and thus provides a stop and prevention of an accident.

In the automatic control system 41, a compressor vibration diagnostic system is provided, namely: the compressor has several sensors for monitoring the compressor vibration displacement and in case of deviations of the vibration displacement values from the norms, an alarm signal is transmitted to the automatic control system 41 to provide diagnostics and service maintenance of the compressor.

The proposed mobile compressor unit for pumping liquefied natural gas vapors can be effectively and reliably used in liquefied natural gas systems and can pump residual low-temperature liquefied natural gas vapors from transport or stationary tanks of liquefied natural gas.

Claims (8)

1. Mobile compressor unit for pumping vapors of liquefied natural gas, characterized in that it includes a piston V-shaped double-row compressor without lubrication of the cylinder-piston group located in a transportable heat-insulated closed container, as well as an inlet heat-insulated pipeline of vapors of liquefied natural gas in communication with the compressor suction cavity , and the output heat-insulated liquefied natural gas vapor pipeline in communication with the compressor discharge cavity, while at the input a pressure regulator and a buffer tank are installed in series in the downstream pipeline in front of the compressor, a buffer tank and a safety valve are installed on the outlet pipe after the compressor in the direction of the medium to discharge the increased pressure of the medium onto the plug, and a remote control shut-off valve is installed on the inlet pipe after the pressure regulator valve for the ability to connect the unit to the purge system of the compressor cavities with compressed nitrogen, and the elements of the unit in contact with achivaemoy fluid are made of cold-resistant material and have thermal insulation. 2. Mobile compressor unit for pumping vapors of liquefied natural gas according to claim 1, characterized in that the cylinder-piston group of the compressor contains piston rods with piston rings made of self-lubricating material. 3. Mobile compressor unit for pumping vapors of liquefied natural gas according to claim 1, characterized in that an electric motor is used as a compressor drive. 4. Mobile compressor unit for pumping vapors of liquefied natural gas according to claim 1, characterized in that the inlet and outlet pipelines are connected to each other by an additional pipeline with a shut-off valve installed on it. 5. A mobile compressor unit for pumping vapors of liquefied natural gas according to claim 1, characterized in that pressure sensors with valve blocks are installed at the inlet and outlet pipelines for monitoring compressor pressures. 6. Mobile compressor unit for pumping vapors of liquefied natural gas according to claim 1, characterized in that it contains an automatic control system. 7. Mobile compressor unit for pumping vapors of liquefied natural gas according to claim 1, characterized in that the container consists of a technological compartment and a control compartment. 8. Mobile compressor unit for pumping vapors of liquefied natural gas according to claim 7, characterized in that at least one compressed nitrogen cylinder of the compressor cavity purge system is placed in the technological compartment of the container.

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