Before operation, the operator shall be familiar with the process flow of the dehydration system
1. Molecular sieve is used as dehydrating agent for CNG dehydration.
2. There are three dehydration methods in CNG station: the high-pressure dehydration method adopted in this station.
Operation essentials of high pressure dehydration unit
1. Be familiar with the structural principle of dehydration equipment, and master the filter, dryer.
Working principle of regeneration gas heater, pressure reducer, cooler and separator.
2. Preparation before startup
(1) The dehydration system of CNG station after new construction and overhaul (after replacing the dehydration agent) must be purged, pressure tested and replaced with air before putting into production (or trial production).
(2) Before startup, turn on the main power supply in the control box, and turn on the control power supply QF1 and the power supply QF2 and QF3 of the heater.
(3) Check the working state of the valve: ① Slowly open the two valves before and after the dryer and the recovery valve on the recovery separator; These three valves must remain normally open during operation. ②. Close the four blowdown valves on the front coarse filter, front oil filter, oil removal filter and recovery separator; The four valves must be normally closed during operation.
3. Startup operation of dehydration system
Before starting the machine for the first time, turn on the main power supply in the control box, turn on the control power supply QF1 and the power supply QF2 and QF3 of the heater. Start the compressor. When the pressure gradually rises, observe the output pressure of the pressure reducer (its output pressure is 0.8MPa), otherwise adjust its output pressure to 0.8MPa. When the pressure of the dryer rises to 10MPa, start the dryer.
4. Shutdown operation of dehydration system
1) Before shutdown, observe the working state of the dryer and make records.
(2) In case of immediate shutdown during operation, when the heating temperature T1 ≥ 1500C or the regeneration temperature T2 ≥ 600C and the compressor is in operation, the compressor shall be shut down immediately after the dryer is shut down and the air source shall be cut off.
(3) When the regeneration tower enters the pressure equalizing state or the regeneration temperature (T2) is lower than 400C, the dryer is in the optimal shutdown period. Of course, it can also be shut down at any time according to the needs. After the shutdown, a blowdown must be conducted.
(4) Just press the stop button once, and the dryer will automatically shut down after a delay of 3 minutes.
(5) Close the front and rear valves of the dryer.
(6) If the shutdown time exceeds 8 hours, please turn off the power switches of the control box: QF1, QF2 and QF3.
5. Blowdown of dehydration system
Blowdown should be conducted before startup or after shutdown or when the system pressure is low (≤ 15MPa). The valve shall be opened slowly during blowdown, and it is strictly prohibited to blow down violently under high pressure. Severe blowdown may cause damage to the filter element. Blowdown interval: 2 hours / time. (the front coarse filter, pre filter, oil removal filter and recovery separator shall be regularly discharged)
6. Patrol and record during operation
Patrol inspection and record shall be conducted every 30 minutes during operation. Inspection contents: ① check whether the output pressure of the pressurizer is 0.8MPa (normal range: 0.8-1.0mpa), or adjust it to the normal range. ② Check whether the throttle valve is frosted, and the throttle valve pipeline must be frosted during regeneration. ③. Check and record whether the reading of the temperature instrument on the electric cabinet is normal. If it is abnormal, the throttle valve shall be adjusted to adjust the temperature to the normal range by controlling the gas flow.
