Process description
Basic process flow:
Before loading the ship, connect the air delivery arm to the ship-shore interface safety device and check whether the components are normal. When everything is normal, start the ship-shore interface safety device and open the air inlet valve. At this time, the oxygen content in the pipeline is detected. When the oxygen content exceeds 6%, the nitrogen pipeline valve is opened, inert gas is introduced, the pipeline is purged, and the pipeline gas is inerted and blown to the oil and gas recovery unit. When the oxygen content is less than 6%, close the nitrogen valve and open the hand valve to prepare for shipment. When the loading operation begins, the oil and gas delivery arm in the cabin enters the entrance of the ship-shore safety device.
As the oil and gas enters, the oil and gas pressure sensor will detect the pressure and send the signal to the ship-shore safety device control system and the oil and gas recovery unit control system. When the oil and gas pressure is greater than the set value of the oil and gas recovery device control system, the air pump of the oil and gas recovery unit Start, send the oil and gas into the oil and gas recovery device for oil and gas recovery.
After the oil and gas enter the ship-shore safety device, the gas-liquid separator is separated for gas-liquid separation. At the same time, it is equipped with a filter, which can avoid the adverse effects of impurities in the oil and gas on the flame arrestor and the induced draft fan. When the filter pressure difference is greater than the set pressure When the value is set, an alarm signal will be generated and sent to the control system. After the gas-liquid separation and filtration, the oil gas flow passes through the flame arrester and then enters the oil and gas pipeline of the oil and gas recovery device.
The flame arrester is an anti-detonation flame arrester, with pressure difference detection at the front and rear. When the pressure difference is greater than the set value, an alarm signal will be issued to remind the need to be cleaned. There are temperature detection points before and after the flame arrestor. When the temperature exceeds the set point, an alarm signal will be issued and the loading operation will be stopped.
During the loading operation, if the oxygen content exceeds 6%, open the nitrogen valve to dilute the inert gas and send out an alarm signal. When the oxygen content exceeds 8%, the alarm signal is issued, and the loading operation is stopped, and the oxygen content is detected. The reason for the excessive amount. If the pressure reaches 14kPa (adjustable according to the setting pressure of the actual tanker's breathing valve), the vacuum/pressure relief valve opens to perform emergency pressure relief.
Note: Each alarm and interlock value in the description of the process flow can be set pertinently on site according to the actual operating conditions.
On a skid chassis, the insulating flange, manual shut-off valve, check valve, oxygen content detector, VOC detector, inerting system, pressure sensor, pressure gauge, discharge pipe, shut-off valve, gas-liquid separator, Flame arrestor, temperature sensor, flow meter.
All the signals of flow rate, oxygen concentration, VOC concentration, pressure, liquid level, differential pressure, temperature and other signals in the above-mentioned devices are integrated into a PLC system. The PLC system sets several interlocks according to standard specifications to control the safe operation of the system.
Before loading the ship, connect the hose or air transfer arm to the ship-shore interface safety device, and check whether the components are normal. When everything is normal, start the ship-shore interface safety device and open the inlet shut-off valve. At this time, the oxygen content in the pipeline is detected. When the oxygen content exceeds the limit, the inert gas inlet valve is opened, the inert gas is introduced, the pipeline is purged, and the pipeline gas is inerted and blown to the oil and gas recovery unit. When the oxygen content is lower than the limit, close the inert gas inlet valve and open the inlet shut-off valve to prepare for shipment. When the loading operation starts, the oil and gas in the cabin enters the inlet of the ship-shore safety device through the hose or the gas transfer arm.
As the oil and gas enters, the oil and gas pressure sensor will detect the pressure and send the signal to the ship-shore safety device control system and the oil and gas recovery unit control system. When the oil and gas pressure is greater than the set value of the oil and gas recovery device control system, the air pump of the oil and gas recovery unit Start, send the oil and gas into the oil and gas recovery device for oil and gas recovery.
After the oil and gas enter the ship-shore safety device, the gas-liquid separator is separated for gas-liquid separation. At the same time, it is equipped with a filter, which can avoid the adverse effects of impurities in the oil and gas on the flame arrestor and the induced draft fan. When the filter pressure difference is greater than the set pressure When the value is set, an alarm signal will be generated and sent to the control system, and an audible and visual alarm will be performed. After the gas-liquid separation and filtration, the oil gas flow passes through the flame arrester and then enters the oil and gas pipeline of the oil and gas recovery device.
The flame arrester is an anti-detonation flame arrester, with pressure difference detection at the front and rear. When the pressure difference is greater than the set value, an alarm signal will be issued to remind the need to be cleaned. There are temperature detection points before and after the flame arrestor. When the temperature exceeds the set point, an alarm signal will be issued and the loading operation will be stopped.
During the loading operation, if the oxygen content exceeds the limit, open the inert gas inlet valve to dilute the inert gas, and send an alarm signal. When the oxygen content exceeds 8%, an alarm signal is issued, and the loading operation is stopped, and detection Reasons for excessive oxygen content. If the pressure reaches 14kPa (adjustable according to the setting pressure of the actual tanker's breathing valve), the vacuum/pressure relief valve opens to perform emergency pressure relief.
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· Anti-corrosion
According to JT/T733 "Technical Conditions for Surface Anti-corrosion Coatings of Port Machinery Steel Structures", the coating options are: 60μm epoxy zinc-rich primer for base coating, 150μm epoxy thick build paint for middle coating, and aliphatic polyurethane surface for top coating Paint 80μm.
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· Inlet end design requirements
The identification mark of the inlet end of the safety device meets the following requirements:
1) Design to prevent wrong connection when connecting the air inlet end to the ship receiving hose.
2) The exterior of the tank or accessories 1m behind the flange of the inlet end must be marked with coloring. The color is red-yellow-red, the red height is 100mm, the middle yellow width is 800mm, and the black "VAPOR" is marked in the yellow area. The font height is not less than 50mm, the red color card number is RAL 3001 (marking color), and the yellow color card number is RAL 1003 (marking color).
3) Insulating flange: The safety device adopts an insulating flange near the inlet flange. The resistance value of the insulating flange is not less than 10MΩ before the water pressure test and not less than 1000Ω after the water pressure test.
The inlet flange of the whole device is connected with the gas delivery arm flange, and the outlet flange is connected with the oil and gas pipeline of the wharf. One set of oxygen content analyzer is not more than 6m away from the inlet end, and the distance from the outlet end of the detonation flame arrester The inlet end does not exceed 18m.
The welding of oil and gas pipelines meets the requirements of China Classification Society (CCS) "Rules for Materials and Welding".
Take inerting purge measures to ensure that the safety threshold is reached.
Using high temperature resistant sealing ring, all sealing performance will not fail in the case of fire.
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· Pressure control requirements
During the loading operation of the tanker, within the range of the cargo loading rate less than or equal to the maximum loading rate, the device can maintain the tank pressure control range of the tank at the lowest set pressure of the vacuum valve (that is, close to the set value of atmospheric pressure) and pressure release The minimum set pressure of the valve (-3.5kPa～14kPa).
This device can monitor the pressure value. The set pressure parameter is 80% of the lowest set pressure and 80% of the highest set pressure as the alarm value. It is controlled by the pressure/vacuum release valve to maintain the tank pressure of the tanker not to exceed the lowest set pressure. And the highest set pressure.
Conditions that the pressure sensor meets:
1) Install the safety device near the air inlet.
2) Action before the pressure in the cargo tank of the tanker exceeds the given pressure range, and trigger an alarm to send out an overpressure audible and visual alarm signal.
3) Provide models to the general control system for orderly control of the general control system to close the air blower or shut-off valve.
4) When the pressure at the air intake end of the device exceeds 14kPa and the pressure release valve opens to release the pressure, the pressure sensor provides a continuous pressure signal; when the pressure continues to increase, the pressure sensor provides an alarm signal.
5) Control this device to receive the oil and gas vacuum pressure value not exceeding -3.5kPa. When the vacuum pressure exceeds 80% of -3.5kPa, the pressure sensor will send out an alarm signal.
6) The pressure sensor is installed between the air inlet of the safety device and the pressure/vacuum release valve.
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· Installation requirements of the discharge pipe
1) The discharge pipe is set between the pressure sensor at the intake end and the shut-off valve, and a high-speed pressure/vacuum release valve and an electric unloading valve are installed at the top.
2) The exhaust port of the pressure/vacuum release valve discharges vertically, and the exhaust port of the electric unloading valve adopts a 90° elbow type and must not face adjacent equipment or pedestrian passages.
3) The height of the discharge outlet shall be no less than 3m from the ground.
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· Pressure/vacuum relief valve requirements
1) The pressure vacuum release valve is set between the inert gas introduction interface and the flame arrestor of the safety device.
2) The set pressure release value is 14kPa, and the vacuum pressure release value is -3.5kPa.
3) The discharge speed is not less than 30m/s.
4) Set up a fire net.
5) Meet the requirements of IMO MSC/Circ.1009 and MSC/Circ.677.
6) Meet the requirements of GB/T19699.
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· Technical requirements for shut-off valve
1) The shut-off valve is installed on the main pipeline between the pressure/vacuum release valve interface and the detonation flame arrestor.
2) Capable of automatic control, remote control, and manual operation.
3) It has local and remote visual indication of valve working position status.
4) Refractory type, meeting the requirements of ISO10497.
5) After receiving the closing or opening instruction signal, the action can be realized within 30s.
6) No perceptible leakage of the sealing material is allowed.
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· Fire, explosion, detonation and detonation protection requirements
According to the oxygen content in the system or the signal detected by the VOC content analyzer, take necessary inerting measures to keep the gas in the terminal oil and gas recovery facility outside the combustible range, and to ensure that the gas concentration in the oil and gas recovery system is within a safe range.
A two-way detonation type flame arrestor is installed near the air outlet of the safety device.
Technical requirements for detonation arresters and fire nets:
1) It can prevent the spread of detonation combustion from either side of the device.
2) Design, manufacture and test meet GB/T13347.
3) The fireproof net is a double-layer net made of corrosion-resistant steel wire with 30×30 grids per square inch, the diameter of the steel wire is not less than 0.3mm, and the distance between the two layers of net is not less than 12.7mm and not more than 38.1mm.
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· Technical requirements for oxygen content analyzer
1) The range is 0-25%, the accuracy is 1%, and the response time does not exceed 30s.
2) Do not use zirconium dioxide method or thermomagnetic method, use laser method.
3) The setting position of the continuous sampling point of oil and gas concentration shall not exceed the distance of 30 times the pipe diameter from the gas injection point.
4) The oxygen content or hydrocarbon content analyzer is installed after the air inlet and before the air inlet of the inerting system.
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· Technical requirements for gas-liquid separator
1) The gas-liquid separator is equipped with a liquid level indicator.
2) The gas-liquid separator is equipped with a control system associated with the remote oil and gas shut-off valve, and its control is set to high-level alarm and ultra-high-level shut-off.
3) The manufacture of the gas-liquid separator shell meets the requirements of GB150.
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· Power requirements
Safety, monitoring and alarm have separate power supply lines in the control system design. When the above power supply loses power, there is still a necessary power supply control system, which can automatically switch to the backup power supply and issue an alarm. The backup power supply only supplies power to the above system, and its capacity can maintain at least 30 minutes of power supply needs.
The design adopts an uninterrupted way to switch to the standby power supply.
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· Safety system design requirements
1) In the event of a serious failure that endangers the safety of cargo ships, oil and gas recovery and processing systems, and tank farms, the control system can automatically generate protective actions and issue alarms.
2) If the operation of the electromechanical equipment is stopped due to the action of the safety function, the equipment should not be automatically put into operation without manual reset.
3) When the oxygen content reaches 6% by volume, an alarm is issued. When the oxygen content reaches 8%, the emergency discharge safety program is started, the solenoid valve is opened, and the shutoff valve is closed.
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· Monitoring function requirements
1) Through a set of monitoring instruments, monitor the oil and gas pressure, oxygen content, VOC content, temperature, flow and other parameters in the ship-shore interface safety device; monitor the possible abnormal conditions of the safety device; monitor the action of the shut-off valve in the safety device, Real-time monitoring of working conditions such as the pressure difference of the flame arrester and the liquid level of the gas-liquid separator.
2) The selection principle of various monitoring instruments is to have the applicability of monitoring objects, the reliability of online monitoring environment, the real-time performance of monitoring precision instruments, and the ease of calibration and reset.
3) All kinds of monitoring instruments and equipment installed on the safety device are easy to maintain and maintain.
4) The electronic signals of monitoring parameters output by various monitoring instruments must match or be compatible with the control system.
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· Alarm function requirements
1) Provide data according to online monitoring of the system. Once a critical condition is reached or an abnormality is found, an alarm will be realized immediately by means of electronic information, sound, light, etc., and an alarm signal will be output and sent out.
2) The alarm information of the safety device is simultaneously output to the terminal oil and gas recovery control station (room).
3) All failures of the monitored equipment/system and the monitoring system itself are displayed in the safety device and the main control station (room) at the same time, and an alarm signal is issued to let the operator know the failure.
Major equipment
1) Manual shut-off valve
Installed on the main pipe near the inlet of the device.
Use petrochemical steel general valves with manual operation function and meet the requirements of GB/T12235.
It has the function of visually indicating the status of the working position.
2) Check valve
Set check valve under specific circumstances of this device:
① Install on the main pipeline of the device close to the manual shut-off valve to prevent backflow to the inlet end of the device;
②The general purpose valve made of petrochemical steel is selected to meet the requirements of GB12235.
3) Electric shut-off valve
(1) Install on the main pipeline between the discharge pipe interface and the detonation arrester.
(2) Select petrochemical steel general valves, with automatic, remote control and manual functions, reliable remote control and local operation functions, after receiving the closing or opening instruction signal, it can realize emergency opening and closing within 30s, and trigger at the same time Call the police.
(3) Fire-resistant type, meeting JB/T6899 requirements, explosion-proof grade Ex dⅡC T4, protection grade IP65;
(4) It has the function of indicating on-site and remote visual working position status.
4) Regulating valve
(1) Installed on the inert gas input pipeline, the inert gas input pipeline is connected with the main pipeline of the device, and the inert gas is provided by the wharf.
(2) The regulating valve is controlled by the PLC control system. It has the functions of controlling the opening and closing of the inert gas input and regulating the flow and pressure of the inert gas. It delivers inert gas to the main pipeline of the device and controls the oxygen content of the oil and gas sent to the main pipeline. Higher than 8% explosion risk.
(3) The electric control valve with higher sensitivity and precision is selected, which meets the requirements of JB/T8528, GB13927, GB12220, explosion-proof grade Ex dⅡB T4, and protection grade IP65.
(4) The specification selection is based on the inerting design of the wharf, and the buyer and the designer provide the seller with the conditions of the inerting system, and the inert gas pipeline size is DN25.
5) Pressure sensor
(1) Install two differential pressure sensors for interlocking control, and install them on the main pipe between the intake end and the discharge pipe of the device.
(2) It has the function of real-time output of detection data and provides signals to the control system of this device.
(3) The range is -10 kPa～100kPa, the accuracy is 0.1%, the explosion-proof grade is Ex dⅡ CT4, the protection grade is IP67, and it meets the requirements of GBT 15478.
6) Pressure/vacuum release valve
(1) Install on the discharge pipe of this device.
(2) Equipped with set value pressure relief function, the pressure release value is 14 kPa, and the vacuum pressure release value is -3.5kPa, which can also be set separately according to the actual situation.
(3) During the entire exhaust process from when the pressure/vacuum release valve reaches the set pressure to the subsequent closing, the exhaust velocity of the gas at the valve port is always not less than 30m/s.
(4) The manufacturing quality of the pressure/vacuum release valve meets the requirements of GB/T 19699.
(5) Install fire retarding elements at the vacuum inlet of the pressure/vacuum release valve, the pressure outlet of the release valve and the vacuum inlet. The fire retarding capability of the fire retarding element covers (not less than) the oil and chemical products in the tanker’s cargo tank. The explosion-proof grade and the maximum safety test gap (MESG) value of the fire resistance component are equipped with a type test report that meets the requirements of IMO MSC/Circ.1324, MSC/Circ.677 (including various amendments).
7) Electric unloading valve
(1) Install on the discharge pipe of this device, in parallel with the pressure/vacuum release valve.
(2) It is used for emergency opening when the oil and gas oxygen content of the main pipeline of this device reaches or exceeds the explosion limit of 8%, and the pressure exceeds the limit.
(3) It can accept the automatic control of this device, and has the function of manual operation control. After receiving the closing or opening instruction signal, the action can be realized within 10s.
(4) Fire-resistant type, meeting the requirements of JB/T6899 standard, explosion-proof grade Ex dⅡC T4, protection grade IP65.
8) Gas-liquid separator
(1) Install between the electric shut-off valve of the device and the detonation-proof flame arrestor.
(2) Equipped with liquid level indication and high liquid level alarm functions to provide signals to the control system of this device.
(3) The equipment material and flange specifications are consistent with the main pipeline of the device.
(4) The equipment manufacturing meets the requirements of GB150, and the equipment is equipped with a filtering structure to filter solid particles. The filtering structure is convenient for cleaning and maintenance. The selection of the filter density is compatible with the maximum safety test gap (MESG) value of the flame arrester to protect the normal flow of the flame arrester in the rear end detonation flame arrester.
(5) The volume of the equipment and the effect of gas-liquid separation are compatible with the maximum oil and gas flow and pressure drop requirements in the main pipeline.
(6) The gas-liquid separation filter equipment is convenient to detect and clean up the clogging of the filter.
9) Oxygen content sensor and VOC meter
(1) This device is equipped with 2 oxygen content sensors, one of which is installed on the main pipeline between the inlet end of the device and the inert gas inlet pipe, and the distance from the inlet end of the device shall not exceed 6m to detect oil and gas in the cabin. The oxygen content of the gas; another oxygen content sensor is installed before the gas outlet of the main pipeline of the device to check the oxygen content of the oil and gas in the main pipeline after the inert gas is supplemented.
(2) This device should be equipped with a vapor concentration VOC tester, installed at the location of the main pipeline of the device.
(3) The oxygen content sensor and VOC meter have the function of real-time output of detection data and provide signals to the control system of the device.
(4) The oxygen content sensor and VOC meter meet the following requirements:
① Range 0-25%, accuracy 1%, response time ≤20 seconds, explosion-proof grade Ex dⅡ CT4, protection grade IP67;
②The oxygen content sensor meets the requirements of the HG 23007 standard, and the VOC meter meets the requirements of the GB15322 standard;
③The working principle of oxygen content sensor adopts laser method;
④The working principle of VOC analyzer adopts PID method.
10) Temperature sensor
(1) This device should be equipped with a temperature sensor, which is installed on the main pipeline of the device.
(2) It has the function of real-time output of detection data and provides signals to the control system of this device.
(3) Range -50℃～150℃, accuracy 0.1%, explosion-proof grade Ex dⅡ CT4, protection grade IP67.
(4) The temperature sensor meets the requirements of GB/T 30825.
11) Anti-detonation flame arrester
(1) This device is equipped with a two-way detonation type flame arrestor, which is installed on the gas-liquid separator and the main pipeline of the gas outlet of the device.
(2) The maximum test safety gap (MGSE) value of the flame arresting gap of the flame arresting element is consistent with the expected characteristics of the oil and gas medium in the cargo tank of the oil tanker, which can prevent the detonation and combustion of the flame from either end of the device.
(3) Product manufacturing meets the requirements of GB/T 13347, and the performance type test of detonation flame arrester meets the requirements of ISO16852.
(4) The two ends of the detonation resistance flame arrester are equipped with differential pressure sensors and temperature sensors, which have the function of real-time output detection data and provide detection signals to the control system of the device.
(5) Install in accordance with the methods and requirements recommended by the manufacturer of the detonation-resistant flame arrestor, and the length of the straight pipe connected at both ends of the flame arrestor meets the requirements of the manufacturer's product installation instructions.
(6) The passing flow of detonation detonation arrester is compatible with the estimated maximum loading capacity. The flow/pressure drop curve of the flame arrester must have a special type test report, and the pressure drop meets the system requirements.
(7) Type test report and qualification certificate for fire resistance performance and flow/pressure drop curve issued by a third-party inspection unit approved by relevant departments for detonation-resistant flame arresters.
12) Flowmeter
(1) This device should be equipped with a flowmeter, which is installed on the main pipe near the outlet of the device.
(2) The detection data has the function of real-time output detection data, and provides signals to the control system of the device.
13) Control system
(1) General requirements
This device is equipped with an automatic control system, and the control cabinet and internal equipment can adapt to the requirements of the predetermined working environment, including ambient air temperature, relative humidity, vibration, salt spray and dust.
The control system can work normally under the standard allowable fluctuation conditions where the power supply voltage and frequency deviate from the rated value. When the harmonic content of the power supply is less than 5%, it can work normally.
The control cabinet of this device uses products of corresponding explosion-proof level, which meets the requirements of GB28526.
The control button can prevent accidental touch and cause malfunction.
(2) Power supply
Safety, monitoring and alarm have separate power supply lines in the control system design. When the above power supply loses power, it can automatically switch to the backup power supply (UPS) to supply power and issue an alarm. Its capacity can maintain at least 30 minutes of power supply. The design adopts an uninterrupted way to switch to the backup power supply.
When installing this device in a thunder-ridden area, install a lightning protection device on the power supply system and field instruments.
(3) Real-time online monitoring, alarm and protection function requirements:
The control system of this device is a subsystem of the general control system of the terminal oil and gas recovery facility. It has the functions of providing various monitoring parameters to the general control system and receiving remote control commands from the general control system; it is easy to check, identify and lock, which can ensure the device’s performance Normal operation and stable work.
With monitoring function, it can work on electric shut-off valve, electric unloading valve, detonation flame arrester, gas-liquid separator, inerting control valve, etc. through monitoring instruments such as pressure, oxygen content, VOC content, temperature, and flow rate of this device. Real-time monitoring of the condition, the electronic signal information of the monitoring parameters output by various monitoring instruments matches or is compatible with the control system, with environmental adaptability, reliability, and easy maintenance.
With alarm function, set the alarm program, according to the real-time online monitoring data, once the critical condition or abnormality is found, the alarm will be realized immediately by electronic information, sound, light, etc., and the alarm signal will be output and sent to the terminal oil and gas recovery control system at the same time output signal.
Satisfy the fail-safe principle and the principle of independence, set the safety protection control program and automatically generate protective action instructions, the controlled equipment, device or system shuts down in an emergency and orderly according to the predetermined shutdown requirements, and has a backup manual control.
When the control system or the master control system fails, fails, or the power source is interrupted, it can send out an alarm signal or switch to local manual control, set an emergency stop button to realize manual operation emergency stop; set the reset control program after the failure shutdown, Without manual reset, the device should not be put into operation automatically.
