On-site expansion filling construction method for pearlife of LNG storage tank

Abstract

The invention discloses a large LNG storage tank pearlife field expansion filling construction method which comprises the steps that an expansion furnace, a dust remover, a pneumatic conveying device and other equipment are installed on a construction field, perlite raw ore sand is transported to the construction field to be subjected to expansion treatment, and a cold insulation layer of a storage tank is filled with expanded pearlife through the pneumatic conveying device; and a good effect can be achieved. The on-site expansion filling method achieves synchronous operation from machining to filling, and the construction period is greatly shortened. Loss and damp risks of materials in the transportation and storage process are reduced, and the overall construction cost is reduced. The pneumatic conveying device is adopted for filling, the situation that gaps or uneven accumulation occurs in the pearlife filling process is effectively prevented, it can be guaranteed that the pearlife is evenly distributed in a cold insulation layer of the storage tank, the cold insulation effect is improved, dust pollution to the environment is reduced, and construction safety is improved.

Description

Technical Field

[0001] The invention relates to the technical field of cold-insulation construction of LNG storage tanks, in particular to a pearlescent sand on-site expansion and filling construction method of LNG storage tanks. Background Art

[0002] Liquefied natural gas (LNG) has extremely high requirements for cold storage of storage tanks due to its low temperature storage characteristics. The cold insulation structure of LNG storage tanks is a key part to ensure the safe and efficient storage of LNG. As an excellent cold insulation material, pearl sand (expanded perlite) is widely used in the construction of cold insulation layer of LNG storage tanks due to its extremely low thermal conductivity and reliable chemical stability.

[0003] Pearlescent sand is made of glassy mountain rock through crushing and high-temperature roasting. It is in the form of loose white round beads and has the characteristics of being non-toxic, odorless, non-flammable and non-corrosive. Its extremely low thermal conductivity and good filling fluidity make pearlescent sand an ideal choice for the cold insulation layer of LNG storage tanks. In addition, pearlescent sand also has good chemical stability and extremely low bulk density, which can effectively reduce the thickness of the thermal insulation layer of the storage tank and improve the thermal insulation effect of the storage tank.

[0004] In the traditional cold insulation construction of LNG storage tanks, pearl sand is mostly filled by manual filling method or factory prefabrication filling method. These methods have many limitations, such as low construction efficiency, high labor intensity, long construction period, and uneven filling due to human factors in the manual filling method; and the factory prefabrication filling method has problems such as high transportation cost and easy moisture and agglomeration of materials, and the above problems are particularly prominent in the filling process of large LNG storage tanks. Summary of the invention

[0005] The purpose of the present invention is to provide an on-site expansion and filling construction method for pearlite sand of LNG storage tanks. This method expands the raw perlite sand directly on the construction site, and fills the expanded pearlite sand into the cold insulation layer of the storage tank through a pneumatic conveying device, thereby improving work efficiency while reducing the overall construction cost, improving the cold insulation effect, and reducing environmental pollution.

[0006] The technical solution adopted by the present invention to solve the technical problem is: an on-site expansion filling construction method of pearl sand for LNG storage tanks, comprising the following steps:

[0007] Step 1: Equipment preparation: Install perlite expansion furnace, cyclone dust collector, pipe radiator, back-blowing bag dust collector, storage device and pneumatic conveying device equipment at the construction site;

[0008] Step 2: On-site expansion of pearl sand: The raw pearlite sand is fed into the expansion furnace through a spiral feeder for heating and expansion. The shape of the flame is protected by combustion wind, and the length of the flame is controlled by induced wind. The flame temperature is maintained at 900℃~1300℃;

[0009] Step 3, cooling and dust removal: The hot air flow carrying pearl sand powder is transported to the cyclone dust collector through the blower for primary dust removal. After air-material separation, the separated pearl sand is transported to the back-blowing bag dust collector, and falls into the storage device after secondary dust removal. The air after primary dust removal flows out from the middle air duct to the radiator of the pipe, and the temperature conducted from the cyclone dust collector is cooled through the radiator of the pipe;

[0010] Step 4: Pneumatic conveying: The pearlescent sand collected in the storage device is conveyed to the cold insulation layer of the LNG storage tank through the pneumatic conveying device and the conveying pipe;

[0011] Step 5, filling and compaction: During the filling process, a vibrator is used for compaction operation, and the tank body is compacted in layers and zones. The vibrator is used for compaction every 2.5m to 3.5m of height to ensure that the pearl sand is densely packed in the cold insulation layer. After the vibration is completed, the settled part is supplemented until it is filled to the required height;

[0012] Step 6. Sealing and inspection: After filling is completed, seal the filling port with a flange and check the thermal insulation effect and quality of the cold insulation layer.

[0013] Furthermore, in the step 2, the air volume of the main pipe and the auxiliary pipe is controlled, and 92% to 98% of the pearlescent sand is carried by the main pipe, and 2% to 8% of the pearlescent sand is carried by the auxiliary pipe.

[0014] Furthermore, in step three, the air intake of the fan is controlled to ensure that the dust bag display temperature is between 130°C and 170°C.

[0015] Furthermore, in step 4, the conveying device automatically adjusts the pressure so that the pearlescent sand is output in laminar pulses.

[0016] Furthermore, in the step 5, in order to ensure the filling and compaction effect, the pearl sand is initially filled to a position above the height of the inner tank top.

[0017] Beneficial effects of the present invention:

[0018] 1. Reduce dust pollution:

[0019] 1) Compared with the traditional manual filling method, the on-site expansion filling method avoids dust pollution during the packaging, storage and transportation of perlite powder. This process directly expands and fills on site, reducing the contact between the material and the external environment, thereby greatly reducing the generation and spread of dust.

[0020] 2) The fully enclosed air conveying device used in the expansion process ensures that the expanded perlite powder can be directly and efficiently filled into the storage tank, further reducing dust leakage.

[0021] 2. Reduce energy consumption and emissions:

[0022] 1) On-site expansion filling method reduces energy consumption and emissions during material transportation. Since the materials are processed and filled directly on site, the energy consumption and exhaust emissions caused by long-distance transportation are avoided.

[0023] 2) Energy efficiency optimization of equipment such as expansion furnaces has also further reduced energy consumption and emission levels.

[0024] 3. Improve resource utilization:

[0025] The on-site expansion filling method reduces the loss of materials during packaging, storage and transportation, improves resource utilization, and also reduces material waste because the filling process is more precise and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0027] The pearl sand on-site expansion filling construction method for LNG storage tanks of the present invention is described in detail below with reference to the accompanying drawings of the specification.

[0028] See also Figure 1 The present invention provides a technical solution: a pearl sand on-site expansion filling construction method for LNG storage tanks, comprising the following steps:

[0029] Step 1: Equipment preparation: Install perlite expansion furnace, cyclone dust collector, row pipe radiator, back-blowing bag dust collector, storage device and pneumatic conveying device equipment at the construction site.

[0030] Step 2: On-site expansion of pearl sand: The raw pearlite sand is fed into the expansion furnace through a spiral feeder for heating and expansion. The shape of the flame is protected by combustion wind, and the length of the flame is controlled by induced wind. The flame temperature is maintained at 900℃~1300℃.

[0031] Step 3: Cooling and dust removal: The hot air flow carrying the pearl sand powder is transported to the cyclone dust collector through the blower for primary dust removal. After air-material separation, the separated pearl sand is transported to the back-blowing bag dust collector, and falls into the storage device after secondary dust removal. The wind after primary dust removal flows out from the middle air duct to the exhaust pipe radiator, and the temperature transmitted from the cyclone dust collector is cooled through the exhaust pipe radiator.

[0032] Step 4, pneumatic conveying: The expanded perlite collected in the storage device is conveyed through the pneumatic conveying device. The conveying device automatically adjusts the pressure to make the expanded perlite output in laminar pulses and convey it to the cold insulation layer of the LNG storage tank through the DN80 conveying pipe to ensure the uniform distribution and effective filling of the expanded perlite. The conveying pipeline uses DN80PE pipes in the tank body and the lower part, and DN80 steel wire hoses on the top of the tank body to facilitate the filling of pearl sand. The conveying pipeline is completely closed.

[0033] Step 5: Filling and vibrating: During the filling process, a vibrator is used to vibrate the tank in layers and zones. The vibrator is used every 2.5m to 3.5m of height to ensure that the pearl sand is tightly packed in the cold insulation layer. After the vibration is completed, the settled part is supplemented until the required height is reached. To ensure the filling and vibrating effect, the pearl sand is initially filled to a position above the inner tank top height.

[0034] During the filling process, a vacuum suction cup vibrator is used for compaction operation. The tank body is vibrated in layers and zones. Vibration points are set around the tank body at an angle of 30° and in alternating layers. The tank body is vibrated once every 3m of height until the settlement per hour is less than 50mm and the settlement at any point is less than 100mm. The density after compaction is measured and the compacted density is sampled every day to ensure the dense accumulation of the expanded perlite in the cold insulation layer. The expanded perlite is initially filled to a position above the inner tank top height. After the vibration is completed, the settled part is supplemented until it is filled to the required height.

[0035] It should be noted that when installing the vibrator, avoid the welds connecting the steel plates and do not vibrate near the reinforcement ring to prevent the corresponding vibration effect from being achieved.

[0036] Step 6. Sealing and inspection: After filling, seal the filling port with a flange, check whether the expanded perlite above the suspended ceiling is uniform, ensure that the filling height of the expanded perlite at any position meets the requirements, and check the insulation effect and quality of the cold insulation layer.

[0037] In step 2, the air volume of the main and auxiliary pipes is controlled, and the main pipe carries 92% to 98% of the pearl sand, preferably 95% of the pearl sand. The auxiliary pipe carries 2% to 8% of the pearl sand, preferably 5% of the pearl sand. After the expanded perlite is foamed, the various indicators of the expanded perlite are checked, and filling can be carried out only if they meet the technical requirements. During the expansion process of the expanded perlite, the particle size screening grade is randomly checked every 8 hours, and the moisture content of the expanded perlite is randomly checked twice a day.

[0038] Furthermore, in step three, the air intake of the fan is controlled to ensure that the dust bag display temperature is between 130°C and 170°C, preferably 150°C.

[0039] In the step 4, the conveying device automatically adjusts the pressure so that the pearlescent sand is output in laminar pulses.

[0040] Before filling with expanded perlite, seal all openings on the suspended ceiling to prevent pearl sand from floating into the inner tank. After filling, clean the expanded perlite powder deposited on the surface of the suspended ceiling.

[0041] The filling of expanded perlite should be a continuous operation. If abnormal operation interruption occurs, measures should be taken to keep the tank dry.

[0042] During the on-site filling construction of expanded perlite, it is necessary to ensure that the pneumatic conveying is in a fully closed state.

[0043] Example

[0044] Take the construction project of the first phase of a storage and distribution station as an example

[0045] Construction preparation

[0046] The inner tank of the LNG storage tank has passed the inspection, the interlayer and retaining wall have passed the inspection and acceptance, the interior has been cleaned, the interlayer has been dried, the top filling hole has been retained, and the LNG storage tank has been filled with pearlescent sand after the process handover procedures have been completed.

[0047] Before filling with expanded perlite, seal all hanging openings to prevent the expanded perlite from floating into the inner tank.

[0048] According to the approved construction organization design requirements, the construction site shall be well connected with "three connections and one leveling" and fire-fighting facilities shall be installed.

[0049] Equipment preparation

[0050] Perlite expansion furnace, cyclone dust collector, row pipe radiator, back-blowing bag dust collector, material storage device, pneumatic conveying device and other equipment are installed at the construction site and fixed in place, isolated, connected to the power supply, maintained and debugged. All construction equipment must be inspected and tested before starting work.

[0051] Pearlescent sand on-site expansion

[0052] The qualified raw perlite sand is accurately and stably fed into the expansion furnace through the speed of the screw feeder, and the raw sand falls to the bottom of the expansion furnace under the action of gravity. The screw feeder is automatically controlled by a portable computer through the interface according to the equipment status.

[0053] The expansion furnace is heated by fuel oil, and the flame temperature is maintained at about 1100℃ for heating and expansion. The expansion temperature is obtained by the diesel oil sprayed through the burner in a mist and fully burned. The temperature is controlled by the sensor and the portable computer automatically adjusts the oil volume through the interface to keep the temperature constant. The standard flame is viewed from the end of the furnace, with a large fire head in the front and a small black core in the middle. The shape of the flame is protected by the combustion wind, and the length of the flame is controlled by the induced wind. The larger the induced wind, the longer the flame.

[0054] Control the air volume of the main and auxiliary pipes. The main pipe carries about 95% of the expanded perlite, and the auxiliary pipe carries about 5% of the expanded perlite. The air volume of the main pipe cannot be changed at will. Since the total air volume of the induced draft fan is fixed, when the air volume of the main pipe increases, the air volume of the auxiliary pipe decreases accordingly. When the cold air inlet plate is opened, the air volume of the main and auxiliary pipes decreases accordingly, the furnace temperature will increase, and the temperature of the back-blowing dust collector and cooler will decrease. Therefore, the operation of the auxiliary pipe valve and the cold air plate should be very flexible.

[0055] After the expanded perlite is foamed, check the various indicators of the expanded perlite. Filling can only be carried out if they meet the technical requirements. During the expansion of the expanded perlite, the particle size screening grade is sampled every eight hours, and the moisture content of the expanded perlite is sampled twice a day.

[0056] Cooling and dust removal

[0057] The hot air flow carrying the expanded perlite powder is transported to the cyclone dust collector by the blower for primary dust removal. After the air and material are separated, the separated expanded perlite is transported to the back-blowing bag dust collector.

[0058] When wind passes through the bags, it will carry expanded perlite, and the expanded perlite will be attached to the high-temperature bags. The wind passing through the back-blowing bag dust collector is from top to bottom. There are 100 high-temperature bags inside, and the high-temperature bags can work continuously below 180°C. The air bag has an air pressure of about 6 kg. The air pressure is released intermittently and regularly into ten rows of high-temperature bags through 10 blowing pipes controlled by ten valves. Then, one of the ten rows of high-temperature bags will blow off the expanded perlite attached to the high-temperature bags under the impact of the airflow from top to bottom, and fall into the storage device after secondary dust removal.

[0059] The wind after the first-stage dust removal flows out from the middle air duct to the exhaust pipe radiator. The temperature transmitted from the cyclone dust collector is cooled by the exhaust pipe radiator and controlled by the air intake volume of the fan to ensure that the temperature displayed by the dust bag does not exceed 150℃.

[0060] Pneumatic conveying

[0061] The expanded perlite collected in the storage device is transported through a pneumatic conveying device. The conveying device automatically adjusts the pressure so that the expanded perlite is output in laminar pulses and is transported to the cold insulation layer of the LNG storage tank at the top expanded perlite filling port through a DN80 conveying pipe to ensure uniform distribution and effective filling of the expanded perlite.

[0062] The conveying pipeline uses DN80PE pipe in the tank body and the lower part, and DN80 steel wire hose is used on the top of the tank body to facilitate the filling of pearl sand. The curve of the conveying pipeline is as smooth as possible and completely closed. A bracket is set every 6 meters for the conveying pipeline. The pipeline is fixed on the equipment escalator (there is no fixed point in other places). The fixed point is repeatedly wrapped with No. 8 iron wire and tied. The conveying pipeline is fixed on the top of the equipment with a hand winch. After the conveying pipeline on the top of the equipment enters the filling port, the filling port is sealed.

[0063] Filling and compaction

[0064] During the filling process, a vacuum suction cup vibrator is used for vibration operation. The tank body is vibrated in layers and zones. The vibration points are set at 30° around the tank body and staggered in the upper and lower layers. The vibrator is installed at the first layer I position and vibration starts for 60 minutes. The vibrator moves to the first layer II position and starts vibration for 60 minutes. Then the vibrator is moved to the III position and starts vibration for 60 minutes. After the first layer of vibration is completed, the vibration equipment is raised by one layer and the above operation is repeated. This operation is repeated in layers around the tank body until the perlite filling height position.

[0065]

[0066] Vibrate once every 3m of filling height until the settlement is less than 50mm per hour and the settlement at any point is less than 100mm. Measure the density after vibration and check the density every day to ensure the tight stacking of expanded perlite in the cold insulation layer. Initially fill the expanded perlite to a position above the inner tank top height. After the vibration is finished, supplement the settled part until it is filled to the required height.

[0067] Sealing and inspection

[0068] After the expanded perlite filling is completed, clean the expanded perlite powder deposited on the surface of the suspended ceiling, seal the filling port with a flange, check whether the expanded perlite above the suspended ceiling is uniform, ensure that the expanded perlite filling height at any position meets the design requirements, and the height difference between the highest and lowest points of the filling surface is no more than 800mm, and check the thermal insulation effect and quality of the cold insulation layer.

[0069] The main materials used are shown in the table below.

[0070]

[0071] The performance indicators of expanded perlite meet the following requirements: loose density 35-55kg / m 3 ; Tap density 48-65kg / m 3 ; The moisture content (mass ratio) should be lower than 0.3%; The thermal conductivity (0℃) should be lower than 0.040W / (m·k).

[0072] The construction machinery and equipment used are shown in the table below.

[0073] Main construction machinery and tools list

[0074]

[0075] Economic benefit analysis. The specific economic benefit analysis is shown in the table below. Compared with the factory prefabricated filling construction method, the project cost was saved by 359,600 yuan, achieving good economic benefits.

[0076] The following table is a comparative analysis of the main direct costs

[0077]

[0078]

[0079] The method of the present invention installs equipment such as an expansion furnace, a dust collector, and a pneumatic conveying device at the construction site, transports the raw perlite ore sand to the construction site for expansion treatment, and fills the expanded pearl sand into the cold insulation layer of the storage tank through the pneumatic conveying device, which can achieve good results. The on-site expansion filling method realizes synchronous operation from processing to filling, greatly shortening the construction period. It reduces the loss and moisture risk of materials during transportation and storage, and reduces the overall construction cost. The use of a pneumatic conveying device for filling can effectively prevent the pearl sand from having gaps or uneven accumulation during the filling process, and can ensure the uniform distribution of the pearl sand in the cold insulation layer of the storage tank, thereby improving the cold insulation effect. It avoids artificial high-altitude open-air operations, reduces dust pollution to the environment, and improves construction safety. Through two-stage dust removal, the particle capture efficiency is improved, the airflow is purified, and direct dust emissions to pollute the environment are prevented.

[0080] The above description is only used to illustrate some principles of the present invention. This specification is not intended to limit the present invention to the specific structure and application scope shown and described. Therefore, all corresponding modifications and equivalents that may be used belong to the patent scope applied for by the present invention.

[0081] Except for the technical features described in the specification, the other technical features are known technologies to those skilled in the art.

Claims

1. The pearl sand on-site expansion filling construction method for LNG storage tanks is characterized by: The following steps are involved: Step 1: Equipment preparation: Install perlite expansion furnace, cyclone dust collector, pipe radiator, back-blowing bag dust collector, storage device and pneumatic conveying device equipment at the construction site; Step 2: On-site expansion of pearl sand: The raw pearlite sand is fed into the expansion furnace through a spiral feeder for heating and expansion. The shape of the flame is protected by combustion wind, and the length of the flame is controlled by induced wind. The flame temperature is maintained at 900℃~1300℃; Step 3, cooling and dust removal: The hot air flow carrying pearl sand powder is transported to the cyclone dust collector through the blower for primary dust removal. After air-material separation, the separated pearl sand is transported to the back-blowing bag dust collector, and falls into the storage device after secondary dust removal. The air after primary dust removal flows out from the middle air duct to the radiator of the pipe, and the temperature conducted from the cyclone dust collector is cooled through the radiator of the pipe; Step 4: Pneumatic conveying: The pearlescent sand collected in the storage device is conveyed to the cold insulation layer of the LNG storage tank through the pneumatic conveying device and the conveying pipe; Step 5, filling and compaction: During the filling process, a vibrator is used for compaction operation, and the tank body is compacted in layers and zones. The vibrator is used for compaction every 2.5m to 3.5m of height to ensure that the pearl sand is densely packed in the cold insulation layer. After the vibration is completed, the settled part is supplemented until it is filled to the required height; Step 6. Sealing and inspection: After filling is completed, seal the filling port with a flange and check the thermal insulation effect and quality of the cold insulation layer.

2. According to claim 1, a large-scale LNG storage tank pearl sand on-site expansion filling construction method is characterized by: In the step 2, the air volume of the main pipe and the auxiliary pipe is controlled, and 92% to 98% of the pearlescent sand is carried by the main pipe, and 3% to 7% of the pearlescent sand is carried by the auxiliary pipe.

3. The pearl sand on-site expansion filling construction method for a large LNG storage tank according to claim 1 is characterized by: In the step 3, the air intake of the fan is controlled to ensure that the dust bag display temperature is between 130° C. and 170° C.

4. According to claim 1, a large-scale LNG storage tank pearl sand on-site expansion filling construction method is characterized by: In the step 4, the conveying device automatically adjusts the pressure so that the pearlescent sand is output in laminar pulses.

5. According to claim 1, a large-scale LNG storage tank pearl sand on-site expansion filling construction method is characterized by: In the step 5, in order to ensure the filling and compaction effect, the pearl sand is initially filled to a position above the height of the inner tank top.

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