First, the disadvantages of mechanical pressure reducing valve:
After the boiler outputs steam, the pressure in the pipeline is generally higher. After arriving at the user's end, it must be decompressed before it can be used by the load. At present, most users use a mechanical pressure relief valve on the front end of the sub cylinder. Although this method is simple, most of them have some disadvantages that cannot be overcome, and the imported pressure reducing valve is expensive. Mechanical pressure reducing valves generally have the following disadvantages:
1. The steam pressure at the rear end will gradually increase when the steam load flow rate is small or without flow, and the set pressure cannot be maintained.
2. In the case of more condensed water in the pipeline, unreliable operation may occur.
3, pressure setting adjustment is not intuitive, inconvenient, in the case of a higher installation position, according to changes in load requirements inconvenient to adjust, can not be long-distance operation adjustment.
4, can not automatically turn off the steam. Some loads need to stop steaming immediately in the event of a power outage or in the presence of a safety hazard. The mechanical pressure relief valve cannot do this.
5. The pressure regulating range of the mechanical pressure reducing valve is limited, and some pressure requirements are particularly low and the load cannot meet the requirements.
6, higher failure rate. It is prone to clogging of capillary or balance holes, deformation, cracking, and leakage of the diaphragm.
Second, the efficient application of Siemens electric valve in steam decompression:
In view of the above problems, I specially designed a modification program for steam decompression of the Siemens steam electric valve. The steam pressure regulation using this solution was stable for two years. In order to have a fault, the above faults were solved. The specific plan is as follows:
1. List of piping connection components: 1 P steam source 2 SF1 2 3 manual shutoff valve 3 GLQ filter 4 DF Siemens electric steam valve VVF45.504 5 P1 2 3 pressure gauge 6 FQG steam distribution cylinder 7 L1 2 3 steam load
2. Component List: 1 K1 Circuit Breaker 2P 5A 2 K2 Circuit Breaker 1P 3A 3 KZQ Digital Loop Regulator RKC CD901 4 CGQ Pressure Sensor Siemens OBE2000-P16 5 T Transformer 220VAC/24VAC 150AV 6 ZXQ Electric Valve Actuator Siemens SKD65
3, RKC controller parameter setting 1, PID can only be set manually according to the actual situation of the load, but also can have automatic calculation (ATU) function completed.
2. SL1 input type select voltage 0~5V voltage input (1110).
3. Select the upper deviation alarm (0001) in SL4 first alarm mode.
4. Select the 4-6mA continuous output (0111) for SL6 control output type.
5, SL7 alarm relay status selection is set to 01, that is, when the alarm alarm 1 NC has changed to NO.
6. The upper limit of the measurement range set by SLH is 8.00, which corresponds to 0.8 Mpa.
7. SLL sets the lower limit of the measurement range to 0.00, which corresponds to 0Mpa.
8, PGDP is set to 2 decimal places.
9, other parameters can use the default value.
4. Attention 1. Pay attention to the selection of the electric valve actuator to reference the steam source pressure and set pressure. The actuator model should be matched with the pressure difference. Otherwise, the actuator may not be closed or opened.
2, pressure sensor should be installed on the sub-cylinder, there must be table bends and a lead pipe, to avoid the impact of the sensor and the temperature is too high, reducing service life.
3, 4 ~ 20mA control signal series into the AL1 and then to the actuator is in order to pressure is higher than the set value, when the alarm value is exceeded, the AL1 action to open the control signal, so that the electric valve is fully closed.
4, the existing settings SL1, SLH, SLL determines the measurement range between 0 ~ 8Mpa, the sensor can measure to 1.6Mpa, if you need a larger measurement range, you need to convert the input signal through an external circuit, and SLH, SLL resets the settings.
5, the measurement shows a slight error when the PB value can be calibrated.
This program pressure display, set directly on the controller, easy to adjust and use, small pressure fluctuations, reliable operation, also help to save steam energy consumption. The price of Siemens steam-operated valves is slightly lower than that of imported mechanical pressure-reducing valves. It is a method worthy of promotion. The disadvantage is that it must be powered, and it cannot be used where there is no power supply.
After the boiler outputs steam, the pressure in the pipeline is generally higher. After arriving at the user's end, it must be decompressed before it can be used by the load. At present, most users use a mechanical pressure relief valve on the front end of the sub cylinder. Although this method is simple, most of them have some disadvantages that cannot be overcome, and the imported pressure reducing valve is expensive. Mechanical pressure reducing valves generally have the following disadvantages:
1. The steam pressure at the rear end will gradually increase when the steam load flow rate is small or without flow, and the set pressure cannot be maintained.
2. In the case of more condensed water in the pipeline, unreliable operation may occur.
3, pressure setting adjustment is not intuitive, inconvenient, in the case of a higher installation position, according to changes in load requirements inconvenient to adjust, can not be long-distance operation adjustment.
4, can not automatically turn off the steam. Some loads need to stop steaming immediately in the event of a power outage or in the presence of a safety hazard. The mechanical pressure relief valve cannot do this.
5. The pressure regulating range of the mechanical pressure reducing valve is limited, and some pressure requirements are particularly low and the load cannot meet the requirements.
6, higher failure rate. It is prone to clogging of capillary or balance holes, deformation, cracking, and leakage of the diaphragm.
Second, the efficient application of Siemens electric valve in steam decompression:
In view of the above problems, I specially designed a modification program for steam decompression of the Siemens steam electric valve. The steam pressure regulation using this solution was stable for two years. In order to have a fault, the above faults were solved. The specific plan is as follows:
1. List of piping connection components: 1 P steam source 2 SF1 2 3 manual shutoff valve 3 GLQ filter 4 DF Siemens electric steam valve VVF45.504 5 P1 2 3 pressure gauge 6 FQG steam distribution cylinder 7 L1 2 3 steam load
2. Component List: 1 K1 Circuit Breaker 2P 5A 2 K2 Circuit Breaker 1P 3A 3 KZQ Digital Loop Regulator RKC CD901 4 CGQ Pressure Sensor Siemens OBE2000-P16 5 T Transformer 220VAC/24VAC 150AV 6 ZXQ Electric Valve Actuator Siemens SKD65
3, RKC controller parameter setting 1, PID can only be set manually according to the actual situation of the load, but also can have automatic calculation (ATU) function completed.
2. SL1 input type select voltage 0~5V voltage input (1110).
3. Select the upper deviation alarm (0001) in SL4 first alarm mode.
4. Select the 4-6mA continuous output (0111) for SL6 control output type.
5, SL7 alarm relay status selection is set to 01, that is, when the alarm alarm 1 NC has changed to NO.
6. The upper limit of the measurement range set by SLH is 8.00, which corresponds to 0.8 Mpa.
7. SLL sets the lower limit of the measurement range to 0.00, which corresponds to 0Mpa.
8, PGDP is set to 2 decimal places.
9, other parameters can use the default value.
4. Attention 1. Pay attention to the selection of the electric valve actuator to reference the steam source pressure and set pressure. The actuator model should be matched with the pressure difference. Otherwise, the actuator may not be closed or opened.
2, pressure sensor should be installed on the sub-cylinder, there must be table bends and a lead pipe, to avoid the impact of the sensor and the temperature is too high, reducing service life.
3, 4 ~ 20mA control signal series into the AL1 and then to the actuator is in order to pressure is higher than the set value, when the alarm value is exceeded, the AL1 action to open the control signal, so that the electric valve is fully closed.
4, the existing settings SL1, SLH, SLL determines the measurement range between 0 ~ 8Mpa, the sensor can measure to 1.6Mpa, if you need a larger measurement range, you need to convert the input signal through an external circuit, and SLH, SLL resets the settings.
5, the measurement shows a slight error when the PB value can be calibrated.
This program pressure display, set directly on the controller, easy to adjust and use, small pressure fluctuations, reliable operation, also help to save steam energy consumption. The price of Siemens steam-operated valves is slightly lower than that of imported mechanical pressure-reducing valves. It is a method worthy of promotion. The disadvantage is that it must be powered, and it cannot be used where there is no power supply.