Cold insulation design of LNG storage tanks and control of factors affecting the quality of pile foundation construction

1、 The purpose of LNG tank insulation design is to meet the requirements of process production, maintain and maximize production capacity, reduce cold loss, save energy, prevent condensation on the outer wall surface of the tank, and change the working environment. The cold insulation structure of low-temperature storage tanks should first consider the cold insulation and thermal insulation properties for storing low-temperature liquids. Different structures and insulation materials should be used according to different storage conditions. For the insulation design of the top of the storage tank, as the insulation material covers the inner tank ceiling, it does not need to bear the pressure of equipment and evaporated gas (only the weight of the insulation material itself). Therefore, the insulation material should have the characteristics of low thermal conductivity and low density. The upper part of the top of the low-temperature natural growth gas storage tank is made of glass wool, with a cold insulation thickness of 500mm. It is laid and installed in 5 layers, with aluminum foil on the outer side of the upper layer of glass wool to prevent expanded perlite or other impurities from entering the inner tank through gaps. Expanded perlite is chosen as the insulation material for the inner and outer wall interlayers, while expanded perlite is used for the side wall insulation. After cooling the storage tank filled with low-temperature liquid, the contraction of the inner tank will result in insufficient expanded perlite filling in the upper and edge areas of the tank's side walls, and the low-temperature storage tank cannot be filled with expanded perlite again after pre cooling. To prevent the entry of humid air, a layer of elastic insulation glass fiber felt is added to the outer wall of the storage tank to avoid secondary filling of perlite and reduce the pressure of perlite on the inner tank wall. The design of cold insulation materials and structures at the bottom of liquefied natural growth gas storage tanks should not only protect and minimize the tank's cold loss, but also ensure that the compressive strength of the insulation materials can withstand the total weight and gas-phase pressure of the inner tank and low-temperature liquid. In the design and construction of a 20000m ³ low-temperature storage tank, the bottom insulation structure is divided into two parts: a pressure bearing ring and a central ring, and different insulation materials are used based on the different pressures borne by various parts of the tank bottom and the principle of minimizing cold loss rate. The pressure bearing ring is the main component that bears the weight of the inner tank, and its strength requirements are relatively high. Therefore, a composite structure of concrete and glass bricks is used as the cold insulation material for the pressure bearing ring. For the bottom center part, using glass bricks alone can meet its strength and cold insulation design requirements. 2、 The factors affecting the construction quality of LNG storage tank pile foundation control. Natural growth gas storage tanks have high requirements for the bearing capacity of the foundation and foundation. Currently, many LNG storage tank foundations in various regions often use direct foundation or pile foundation. The Tianjin LNG storage tank is built in an underwater fan-shaped area formed mainly by sedimentation of silt in the Bohai Bay. This type of naturally growing foundation soil generally cannot meet the requirements for settlement and deformation caused by upper structural loads. Pile foundation is a deep foundation in which the top of several piles are connected as a whole by a bearing platform to jointly bear the load. Therefore, it has great integrity and stiffness, and can meet engineering requirements. The geology of Tianjin LNG station is different from other regions, with a pile foundation of 55m, making construction difficult. If the construction quality is not strictly controlled, it will leave hidden dangers to the engineering cost, construction period, and even the safety of LNG storage tanks in the later stage of use. Proper handling of quality issues and hidden dangers during pile foundation construction is crucial to prevent similar problems from occurring. Prepare technical documents, engineering materials (equipment), and construction machinery before construction. The control work of on-site construction personnel plays a very important role in smooth construction, and construction quality supervision is the key to protecting construction quality. A full process supervision team should be adopted. 1) Control of construction documents. Before construction, carefully carry out the drawing review work in accordance with the requirements of the program documents and relevant management regulations, carefully review and verify the corresponding construction drawings and construction plans, timely report design defects and quality problems in the plans, and avoid quality problems caused by technical defects. 2) Control of construction materials. The purchased materials meet the requirements specified in the design and contract, and timely witness sampling and re inspection of the incoming materials and equipment shall be carried out. Materials and equipment that do not meet the requirements shall be removed from the site; Materials that meet the requirements should be stored in a timely manner and recorded in a ledger. 3) Control of construction equipment. Choosing appropriate construction equipment plays a crucial role in protecting construction quality and improving construction efficiency. During the construction process, it is necessary to strictly strengthen the inspection of construction equipment, and construction equipment that does not meet the requirements for use shall not be used. 4) Control of construction personnel. Improve construction organization, clarify the responsibilities of construction personnel, and ensure that each person performs their duties. Operators should be familiar with the construction process, hold certificates, and pay special attention to the role of construction technicians and construction supervisors. 5) Control of construction environment. A good construction environment is an important condition for protecting the quality and performance of engineering projects. In actual engineering construction, attention should be paid to taking corresponding measures for abnormal environmental conditions, such as construction during winter and rainy seasons, hot seasons, and windy seasons. Appropriate control measures should be developed for different seasons to avoid hazards such as freezing damage, cracking, and erosion, thereby protecting the quality of the project.