GB/T 22724-2022Installation and equipment for liquefied natural gas—Design of onshore installations (English PDF)

3.1 Natural gas liquefaction plant

A site where gaseous natural gas is processed into liquefied natural gas.

Note: It generally includes production units, such as natural gas (raw gas) purification, natural gas fractionation, natural gas liquefaction (5.1.1), product storage and product loading (in ships or trucks).

3.2 Primary container

Containers, which are used to contain cryogenic liquids and in direct contact with cryogenic liquids.

3.3 Secondary container

Container, that is generally located outside the primary container and holds cryogenic liquid when it leaks. It is not in contact with cryogenic liquid, under normal operating conditions. [Source: GB/T 8423.3-2018, 5.2.25]

3.4 Membrane tank

A composite structure, that can store cryogenic liquids, as composed of a thin steel primary container (i.e., membrane), insulation layer, prestressed concrete tank. [Source: GB/T 8423.3-2018, 5.2.31]

4.2 Environmental impact

4.2.2 Station emissions

During the design process, it shall formulate plans, to avoid and reduce emissions, which are caused by facility test run, operation, maintenance. It shall clarify the pollutant emissions and emission limits.

4.2.3 Emission control

The following emissions shall be controlled, under the premise of safety.

4.2.4 Flaring and venting

The design principle of the station is that there is no continuous discharge of flare gas or vent air to the flare or venting system, under normal operating conditions. Design reasonable measures, to ensure that the waste gas generated during normal operation is recovered as much as possible AND shall not be discharged to the flare or vent system.

4.2.5 Noise

Station design shall take measures, to control noise, to reduce the impact on people exposed to the station and the communities surrounding the station.

Noise control at the station shall meet the requirements of GB 12523 and GB 12348.

4.3 Security

4.3.3 Climate

Climate studies shall include.

4.3.4 Earthquakes

4.3.4.1 Earthquakes are divided into horizontal earthquakes and vertical earthquakes. Acceleration shall be described, according to GB 50011, as follows.

4.3.4.8 The return period for an SSE earthquake is 2475 a (50 a exceedance probability is 2%); the return period for an OBE earthquake is 475 a (50 a exceedance probability is 10%).

4.3.5 Location

4.3.5.1 During the feasibility study stage of the project, it shall finish the project site location evaluation, to ensure that the site selection plan is compatible with regional development. The evaluation shall include at least the following factors.

4.3.5.2 After site selection, a detailed site selection evaluation shall be conducted. The method and scope of site selection evaluation shall consider the total amount and scale of hazardous materials, in the proposed station and surrounding built and planned projects.

4.5 Safety design

4.5.1 Cryogenic equipment and piping design

For the pipes and equipment, the design pressures and temperatures shall cover all expected operating and abnormal conditions.

It shall include physical phenomena, such as possible liquid impact, cavitation, flash evaporation, two-phase flow.

5.1 Composition

Liquefaction devices usually refer to the process systems in natural gas liquefaction plants and LNG peak shaving stations, which consist of natural gas purification, liquefaction, LNG storage.

5.3 Natural gas liquefaction

5.3.1 LNG quality indicators shall comply with the provisions of GB/T 38753.

5.3.2 Denitrification facilities shall be set up, during the natural gas liquefaction process, according to the nitrogen component content in the raw gas and the requirements for LNG indicators in GB/T 38753.

5.3.3 The main heat exchanger of the liquefaction device can be a tube-wound heat exchanger or a plate-fin heat exchanger. It shall take anti-freezing and thawing measures, for equipment and pipelines that may be blocked due to freezing.

5.4 Storage

LNG storage shall comply with the provisions of Chapter 6.

Hydrocarbon refrigerants are generally stored at room temperature, whilst ethylene and liquid nitrogen shall be stored at low temperatures. Refrigerant storage shall comply with the provisions of 7.5 in GB 51261-2019.

6.1 General requirements

The design and construction of vertical cylindrical flat bottom LNG storage tanks shall comply with the provisions of GB/T 26978 (all parts).

6.3 Design principles

6.3.2 Fluid sealing

6.3.2.1 The storage tank shall be well sealed, under normal operating conditions.

6.4 General design principles

6.4.1 The design of the storage tank structure shall be able to withstand the actions of load combinations, which are specified in GB/T 26978 (all parts), meanwhile meet the following requirements.

6.5 Foundations

6.5.1 The design of the foundation shall ensure that uneven settlement complies with the requirements of GB 51156-2015.

6.6 Field instruments

6.6.1 Overview

6.6.1.1 The instrument settings shall meet the requirements for safe and reliable commissioning, operation, production maintenance, shutdown of the storage tank. Instruments include at least the following.

7.1 General requirements

7.1.1 This Chapter specifies the minimum requirements for the design, manufacturing, installation, testing, operation, maintenance of LNG centrifugal pumps (hereinafter referred to as LNG pumps), as well as their drives and auxiliary equipment.

7.1.2 The design, installation, operation of LNG pumps in the station area shall meet the safety technical requirements of GB 51156-2015 and the safety requirements of 4.5.

7.3 Specific requirements

7.3.1 Each LNG pump shall be equipped with an independent valve, to facilitate isolation, draining, purging during pump maintenance.

7.3.2 LNG pumps operating in parallel shall be equipped with outlet check valves; meanwhile it shall take measures, to prevent water hammer on the check valves.

7.3.3 A minimum return valve shall be configured, to prevent the pump from operating at minimum continuous flow.

7.3.4 Pumps installed in LNG pump tanks and pump wells shall be equipped with exhaust pipelines or have exhaust functions.

7.4 Inspection and test

Inspections and tests shall be carried out, in accordance with Appendix E, to verify the operability of the pump, under all working conditions.

8.1 General requirements

8.1.1 Function

The function of the vaporizer is to gasify and heat LNG. The temperature of the heated natural gas shall be higher than the hydrocarbon dew point and not lower than 0 °C.

8.1.3 Natural gas circuit

8.1.3.1 At the outlet of the vaporizer, the pipe material shall be selected, based on the following conditions, considering the lowest temperature that may occur at the outlet of the vaporizer, depending on the following conditions.

8.1.5 Safety valve

8.1.5.1 The discharge capacity of the safety valves of open rack vaporizers, intermediate fluid vaporizers, immersed combustion vaporizers, ambient air vaporizers shall comply with the requirements of GB 51156-2015.

8.1.5.2 Any other type of vaporizer, that can be isolated (blocked), shall be equipped with at least one set of safety valves. The rated displacement of the safety valves shall be calculated, according to the following requirements.

8.1.6 Stability

The vaporizer shall operate stably and without vibration, within the operating range.

8.1.7 Performance data

The manufacturer shall specify the following performance values of the vaporizer.

8.2 Design conditions

8.2.1 Actions

The design of the vaporizer shall include the following actions.

8.3 Vaporizer

8.3.1 Performance parameters

The design of the LNG vaporizer shall be as specified in Table 3, providing parameters and ranges corresponding to different equipment types.

8.3.5.4 Vibration

The design shall prevent vibrations, which are caused by flue gases passing through the water bath, from damaging equipment components.

8.3.5.5 Winter antifreeze

It shall take Winter antifreeze measures.

8.3.5.6 Microbial prevention and control

Effective measures shall be taken, during water bath operation, to prevent the growth of microorganisms.

9.1 Piping system

9.1.1 Overview

The pipeline system of the LNG station includes.

9.1.3 Auxiliary process piping system

Auxiliary process piping systems include.

9.1.4 Public piping systems

9.1.4.1 Depending on the type of station, the main public piping systems include.

9.3.4 Before pressure test and water filling, the pipeline supports and hangers shall be installed and inspected to be qualified.

9.3.5 During pressure testing, the design of the system and boundary areas shall reduce the number of "golden mouths" (welds that cannot participate in the hydraulic pressure test).

9.3.6 After flushing and reinstalling the online instrument, when the system needs to be repressurized, the flange connection shall be checked for leaks, including the inspection of the "gold mouth".

9.4 Pipe components

9.4.1 General

9.4.1.1 The materials of LNG pipeline components shall comply with the provisions of 7.1 in GB/T 19204-2020 and GB/T 51257.It shall also comply with the following

9.5 Valves

9.5.1 Low-temperature valves shall comply with the requirements of GB/T 24925,

GB/T 51257, JB/T 12621.

9.5.2 Low temperature valves shall be able to operate normally, under frost conditions.

9.5.3 Under low temperature conditions, split valves should not be used.

9.5.4 Valves, which are installed on pipelines for low-temperature hydrocarbon media and toxic media, should be connected by butt welding. The internal parts of low- temperature welded valve shall meet online maintenance requirements.