CN214528882U

CN214528882U - Device for improving energy-saving effect and stability of recondenser

Info

Publication number: CN214528882U
Application number: CN202120570802.1U
Authority: CN
Inventors: 刘玉丰; 鹿洋; 刘鹏; 伊晓冬
Original assignee: Xindi Energy Engineering Technology Co Ltd
Current assignee: Xindi Energy Engineering Technology Co Ltd
Priority date: 2021-03-19
Filing date: 2021-03-19
Publication date: 2021-10-29
Anticipated expiration: 2031-03-19

Abstract

An apparatus for increasing the energy savings and stability of a recondenser, comprising: the shell side inlet of the BOG precooler is connected with the outlet of the BOG compressor through a pipeline, the shell side outlet of the BOG precooler is connected with the gas phase inlet of the recondenser through a pipeline, the tube side inlet of the BOG precooler is connected with a cold NG gas pipeline in the middle section of the IFV gasifier through a pipeline, the tube side outlet of the BOG precooler is connected with the inlet of the CNG compressor through a pipeline, a temperature control loop is arranged between the shell side outlet pipeline and the tube side inlet pipeline of the BOG precooler, and the temperature control loop controls the flow on the tube side inlet pipeline according to parameters measured on the shell side outlet pipeline. The utility model discloses the effectual energy-conserving effect that improves the recondenser, very big reduction the investment cost of CNG compressor to the operation of recondenser is stabilized to usable multiple mode.

Description

Device for improving energy-saving effect and stability of recondenser

Technical Field

The patent of the utility model relates to a LNG receiving station field, concretely relates to improve device of recondensor energy-conserving effect and stability, the device can improve the energy-conserving effect of recondensor, realizes the compression to CNG simultaneously.

Background

As a clean and efficient energy source, the share of Liquefied Natural Gas (LNG) in the civil and industrial fields is increased year by year, particularly the supply and demand relationship of domestic LNG is seriously influenced by 'gas shortage' in 2017 winter, and an LNG receiving station is very important to various construction companies because the LNG receiving station has huge economic benefits and provides a continuous gas source for protecting the blue-day working energy.

In the field of LNG receiving stations, with the establishment of gasification output, a recondenser is generally applied to LNG receiving stations at home and abroad as an energy-saving process scheme. Because the working condition of the receiving station is complex, especially under the working condition of ship unloading, the BOG production is several times of that at ordinary times, in addition, the temperature of BOG gas can reach 90 ℃ when the BOG compressor is started, and the two working conditions influence the stable operation of the recondenser.

Meanwhile, a part of LNG receiving stations are provided with CNG compressors, 20KPag BOG gas is pressurized to 25MPag, a large amount of electric energy is consumed, and the high compression ratio of the CNG compressors increases the equipment investment cost.

Operators of the LNG receiving station can form a set of complete debugging operation rules after long-time exploration.

The above system has the following problems in the practical engineering case:

1. the BOG gas temperature in the recondenser fluctuates, affecting the stable operation of the recondenser.

2. The CNG compressor has high compression ratio and increases construction cost.

3. Unstable operation of the recondenser affects the operational risk of the LNG receiving station.

SUMMERY OF THE UTILITY MODEL

The invention aims to solve the technical problems and provides a device for improving the energy-saving effect and the stability of a recondenser, which comprises a brand-new BOG precooling system, a BOG precooler, a CNG compression system, a BOG temperature control loop, necessary pipelines and an automatic control system.

According to one embodiment of the present invention, there is provided an apparatus for increasing the energy saving effect and stability of a recondenser, the apparatus comprising: the shell side inlet of the BOG precooler is connected with the outlet of the BOG compressor through a pipeline, the shell side outlet of the BOG precooler is connected with the gas phase inlet of the recondenser through a pipeline, the tube side inlet of the BOG precooler is connected with the cold NG gas pipeline in the middle section of the IFV gasifier through a pipeline (cold NG gas pipeline), the tube side outlet of the BOG precooler is connected with the inlet of the CNG compressor through a pipeline, a temperature control loop is arranged between the shell side outlet pipeline of the BOG precooler and the tube side inlet pipeline of the BOG precooler, and the temperature control loop controls the flow on the tube side inlet pipeline according to parameters measured on the shell side outlet pipeline.

Further, the temperature control loop comprises a temperature transmitter arranged on a BOG outlet pipeline of the BOG precooler, a pneumatic regulating valve and an actuating mechanism arranged on a pipeline (namely a BOG precooler cold NG gas phase pipeline) between a tube side inlet of the BOG precooler and the middle section cold NG gas pipeline of the IFV gasifier, and a DCS temperature display and controller simultaneously connected with the temperature transmitter, the pneumatic regulating valve and the actuating mechanism.

Further, a flow meter (DCS system flow display) is arranged on a pipeline between the tube side inlet of the BOG precooler and the middle-section cold NG gas pipeline of the IFV gasifier.

Furthermore, the DCS temperature display and controller is connected with the temperature transmitter, the pneumatic regulating valve and the actuating mechanism through hard wires, and controls the operation of the pneumatic regulating valve and the actuating mechanism according to parameters transmitted by the temperature transmitter.

The utility model discloses an improve the energy-conserving effect of recondensor and the operation process of the device of stability as follows: the cold NG gas introduced from the middle section of the IFV gasifier exchanges heat with the outlet gas of the BOG compressor in the BOG precooler to precool the BOG gas, the cold NG flow is controlled by the temperature of the precooled BOG gas, and the heated NG is connected to the CNG compressor through a pipeline. The temperature control loop is composed of a temperature transmitter, a hard wire, a pneumatic regulating valve and a DCS temperature display and controller. On one hand, the temperature of the outlet of the BOG compressor is controlled, the influence on the stability of the recondensor in the starting process of the compressor is avoided, and on the other hand, the heat exchange of the recondensor is a means for energy cascade utilization.

The system is suitable for LNG receiving stations where recondensors are proposed or built.

The main BOG treatment process scheme of the established LNG receiving station is that BOG gas is pressurized to 0.7-0.9 MPag through a BOG compressor, meanwhile, LNG liquid from an inner pump of an LNG storage tank is in direct contact heat exchange with BOG in a packed bed of a recondenser, and the BOG gas can be condensed by effectively utilizing the supercooling degree of pressurized and supercooled LNG. The recondenser is used as a core device of the LNG receiving station, is limited by complex factors of operating condition changes of the LNG receiving station, and how to realize stable operation of the recondenser becomes a most concerned problem for operators of the LNG receiving stations.

In the starting process of the BOG compressor, because the pressure of the outlet needs to be gradually stabilized, the pressure of the outlet of the BOG compressor needs to be continuously and slowly increased by the spraying of the desuperheater through the opening of the reflux valve, the temperature of the BOG gas after being increased is increased along with the increase of the pressure, the temperature of the outlet of the compressor is further increased after the BOG gas reflows to the inlet of the BOG compressor and is increased, and the temperature of the outlet of the BOG compressor can reach 90 ℃ in a short time as proved by field operation experience.

Fluctuations in the BOG temperature affect the flow of LNG into the recondenser, further affecting the stable operation of the recondensing system, and also affecting the energy saving of the recondenser.

The utility model discloses further provide a system and method for improving recondensor energy-conserving effect and stability, the method includes:

and arranging a BOG precooler, introducing BOG gas at the outlet of the compressor into the shell pass of the BOG precooler, introducing NG gas in a cold state in the middle section of the IFV gasifier into the tube pass of the BOG precooler, and indirectly exchanging heat with the BOG gas. The cold NG can be used as the raw material of a CNG compressor after being heated by the BOG, and is further boosted to 25MPag and sent to the downstream. The BOG gas is cooled and then fed to a recondenser.

The BOG precooler temperature control system is characterized in that a set of temperature control system (temperature control loop) is arranged, a temperature transmitter is arranged on the BOG outlet side of the BOG precooler, the temperature of BOG gas is monitored, the BOG gas is sent into a DCS through the temperature transmitter (DCS temperature display and controller), the temperature is converted and sent to a pneumatic regulating valve and an executing mechanism in the DCS, and then the cold NG flow entering the BOG precooler is controlled (the cold NG gas flow is regulated by opening a large valve or a small valve), meanwhile, the temperature set value of the BOG gas can be reasonably set by an operator according to the actual operation working condition, and the operation experience is combined to intervene manually. For example, an operator can manually determine the temperature of the BOG of the recondenser, the unloading condition and the starting condition of the BOG compressor according to the working condition of the LNG receiving station, the temperature of the BOG can be set to be a low value in a central control room, the normal operation condition is set to be a high value, and meanwhile, the temperature control loop can be placed in an automatic control mode, and the control loop automatically executes the following operations: the flow of the cold NG gas is automatically adjusted, the temperature of BOG entering the recondenser is controlled to be maintained at a stable value, and the stable operation of the recondenser is ensured.

The matched CNG compressor directly pressurizes the heated natural gas to 25MPag and sends the heated natural gas to the downstream, thereby effectively reducing the compression ratio of the CNG compressor and achieving the effect of energy conservation.

The utility model discloses following beneficial effect has:

1. the energy-saving effect of the recondenser is effectively improved.

2. The investment cost of the CNG compressor is greatly reduced.

3. The stable operation of the recondenser is stabilized in a number of ways.

4. The heat exchanger provides a buffer space, and can effectively stabilize the pressure fluctuation of a high-pressure system.

Drawings

Figure 1 is a schematic view of an apparatus for increasing the energy saving and stability of a recondenser.

Description of reference numerals: 1: BOG compressor, 2: BOG precooler, 3: IFV gasifier, 4: recondenser, 5: CNG compressor, TE 01: temperature transmitter, TIC 01: DCS system temperature display and controller, TV-01: temperature regulating valve and actuator, FI 01: the solid line in the figure is a pipeline, and the dotted line is a meter hard line. All signals of the instrument are displayed in the DCS system.

Detailed Description

Hereinafter, the present embodiment will be described in further detail with reference to fig. 1.

An apparatus for increasing the energy savings and stability of a recondenser, as shown in fig. 1, comprising: the system comprises a recondenser 4, a BOG compressor 1, an IFV gasifier 3, a BOG precooler 2, a CNG compressor 5 and a temperature control loop, wherein a shell-side inlet of the BOG precooler 2 is connected with an outlet of the BOG compressor 1 through a pipeline, a shell-side outlet of the BOG precooler 2 is connected with an inlet of the recondenser 4 through a pipeline, a tube-side inlet of the BOG precooler 2 is connected with a middle-section cold-state gas pipeline NG of the IFV gasifier 3 through a pipeline, a tube-side outlet of the BOG precooler 2 is connected with an inlet of the CNG compressor 5 through a pipeline, the temperature control loop is arranged between the shell-side outlet pipeline of the BOG precooler 2 and the tube-side inlet pipeline of the BOG precooler 2, and controls the flow on the tube-side inlet pipeline according to parameters measured on the shell-side outlet pipeline.

The temperature control loop comprises a temperature transmitter TE01 arranged on a BOG outlet pipeline (shell pass outlet pipeline) of the BOG precooler, a pneumatic regulating valve and an actuating mechanism TV-01 arranged on a pipeline (a BOG precooler cold state NG gas phase pipeline or a tube pass inlet pipeline) between a tube pass inlet of the BOG precooler and a middle section cold state NG gas pipeline of the IFV gasifier, and a DCS system temperature display and controller TIC01 simultaneously connected with the temperature transmitter TE01, the pneumatic regulating valve and the actuating mechanism TV-01.

And a flow meter FI01(DCS system flow display) is further arranged on a pipeline between the tube side inlet of the BOG precooler and the cold NG gas pipeline in the middle section of the IFV gasifier.

The DCS temperature display and controller TIC01 is connected with the temperature transmitter TE01, the pneumatic control valve and the actuating mechanism TV-01 through hard lines, and controls the operation of the pneumatic control valve and the actuating mechanism TV-01 according to parameters transmitted by the temperature transmitter TE 01.

And the BOG after temperature and pressure rise enters the shell side of the BOG precooler 2 to exchange heat with the cold NG gas.

And a temperature transmitter TE01 is arranged at the BOG outlet of the BOG precooler, the information of the converted electric signals is transmitted to a DCS temperature display and controller TIC01 through a hard wire, the electric signals after operation are transmitted to a pneumatic control valve and an execution mechanism TV-01, and the opening degree of the control valve is controlled so as to control the flow rate of the cold NG gas entering the BOG precooler (the opening degree of the large valve or the small valve is used for regulating the flow rate of the cold NG gas).

And the cold NG gas enters the tube pass of the BOG precooler to exchange heat with the heat flow BOG and increase the temperature, and the flow of the cold NG gas is controlled by a pneumatic regulating valve and an actuating mechanism TV-01 which are arranged on a pipeline.

The heated NG gas is sent to the downstream, and because the NG gas is gasified by boosting and is heated by the heat exchanger, a part of energy consumption is saved by the pressure before being sent to the CNG compressor, so that the compression ratio of the CNG compressor is greatly reduced, and the investment cost of the CNG compressor is reduced.

BOG gas subjected to heat exchange and temperature reduction enters a downstream recondenser, a temperature monitoring control loop is arranged at a BOG outlet of the BOG precooler, so that the temperature of BOG flowing out of the BOG precooler is maintained in a constant interval, on one hand, the BOG subjected to temperature reduction improves the energy-saving effect of the recondenser, on the other hand, a receiving station is in the process of working condition change for a long time, especially, the recondenser is often in the working condition change process, the temperature is controlled at a stable value, so that the fluctuation of recondensation is reduced by one factor, and the stable operation of recondensation is facilitated.

The equipment that operates steadily is further favorable to prolonging the life of whole device.

The advantages of the above device include:

(1) the energy consumption of the LNG receiving station is greatly reduced, and a novel BOG processing mode is provided.

(2) The energy is utilized in a gradient manner, and the cold energy utilization efficiency of the receiving station is improved.

(3) The stable operation degree of the recondenser is improved, and the service life of the whole system is prolonged.

(4) The operation cost of the CNG compressor is reduced.

(5) The heat exchanger provides a buffer space, and can effectively stabilize the pressure fluctuation of a high-pressure system.

The above description is only the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. An apparatus for increasing the energy savings and stability of a recondenser, comprising: the shell side inlet of the BOG precooler is connected with the outlet of the BOG compressor through a pipeline, the shell side outlet of the BOG precooler is connected with the gas phase inlet of the recondenser through a pipeline, the tube side inlet of the BOG precooler is connected with the cold state NG gas pipeline in the middle section of the IFV gasifier through a pipeline, the tube side outlet of the BOG precooler is connected with the inlet of the CNG compressor through a pipeline, and a temperature control loop used for controlling the flow on the tube side inlet pipeline according to the parameters measured on the shell side outlet pipeline is arranged between the shell side outlet pipeline of the BOG precooler and the tube side inlet pipeline of the BOG precooler.

2. The apparatus of claim 1, wherein the temperature control loop comprises a temperature transmitter disposed on a BOG outlet line of the BOG precooler, a pneumatic regulating valve and actuator disposed on a line between a tube-side inlet of the BOG precooler and the intermediate stage cold NG gas line of the IFV gasifier, and a DCS system temperature display and controller connected to both the temperature transmitter and the pneumatic regulating valve and actuator.

3. The apparatus of claim 1 or 2, wherein a flow meter is further provided on a conduit between the tube-side inlet of the BOG precooler and the intermediate stage cold NG gas line of the IFV gasifier.

4. The apparatus of claim 1 or 2, wherein the DCS temperature display and controller is connected to the temperature transmitter and the pneumatic control valve and actuator by hard wires and controls the operation of the pneumatic control valve and actuator according to the parameters transmitted from the temperature transmitter.

5. The apparatus of claim 1 or 2, wherein the tube-side inlet of the BOG precooler is connected to an intermediate stage cold NG gas line of the IFV gasifier by a cold NG gas phase conduit.