When the fan is operated at different wind pressures, it has a strict range of suction air volume. Below this limit, surge will occur, which will cause damage to important blades such as fan blades.
The anti-surge control adopts an adaptive follow-up control method, which uses an online test to measure a representative surge point and makes an anti-surge response curve as a control line. Through the curve function, the pressure limit value is calculated at any time based on the measured differential pressure value, and is used as the set value of the controller, and is controlled by the PI formula. In order to ensure the reliable operation of the system, the following optimization measures have been taken:
(1) Nonlinear control When the negative deviation value increases rapidly, it automatically switches into the large gain fast action zone to accelerate the adjustment function.
(2) The asymmetrical output is output as it is when the control signal is reduced; when the control signal is increased, the output value is delayed by stepwise to ensure the system is stable.
(3) Ramp function When the fan is started/stopped, the ramp function is automatically added to ensure smooth loading or unloading.
The air volume control is adjusted, the air supply volume of the unit is set, and the air volume is kept constant. Wind pressure control is used to limit wind pressure to within limits.
In addition, in order to ensure accurate and rapid conversion to the standby CPU when the main CPU fails, the standby CPU can run synchronously and correctly, ensuring the system is stable and reliable. The primary and backup CPUs need to have the same program, and must also be in the main CPU. The necessary data other than I/O is continuously transferred to the standby CPU. To do this, you need to write another hot standby block to make the data that the main CPU needs to transfer into a special data block, each block of 64 words, the first two words are the status code and the module identification code, and block transfer instructions are used. Transfer. After the standby CPU receives the data according to the identification code, it is transferred to the corresponding data table file to ensure the correct execution of the program.
Welded Bed Plate For Flanges Of Ship Pipe
The flange welded single-sided seat plate is mainly installed on the top, side wall and bottom of the cabin or cabinet as the entrance and exit of the cabin or cabinet. Valves, accessories or pipes can be installed directly on the single-sided seat plate.
Flange welded single-sided seat plate is suitable for seawater, fresh water, oil, air and steam pipelines below 300 °C. The commonly used nominal diameter is 15~150 mm, and the nominal pressure is lower than 1.6 MPa. The shape of the single-sided seat plate is similar to the corresponding lap-welded Steel Flange.
Flange welded double-sided seat plates are generally used when pipelines pass through decks and tanks, and the two sides of the seat plate are respectively connected to valves, accessories or pipes.
Compared with the single-sided seat plate, the double-sided seat plate has an extra shoulder and double-sided mounting stud bolts. The outer diameter of the shoulder is 10~20 mm larger than that of the corresponding flange, and the thickness of the shoulder is 6~12 mm.
Its scope of application and other structural dimensions are basically the same as those of the single-sided seat plate.
The manufacturing and installation methods of the flange-welded double-sided seat plate are basically the same as the single-sided seat plate, but when the screw holes are drawn, the positions of the upper and lower screw holes of the seat plate must be staggered from each other and must not overlap; deck or bulkhead The diameter of the hole on the top is 2~3 mm larger than the diameter of the seat plate.
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