HydroCOM system unit components and control process HydroCOM is easy to operate in actual operation, but it is a relatively complex system consisting of several units. Taking the secondary compressor as an example, the following figure is a typical HydroCOM configuration structure. HydroCOM system configuration actuator HA: The actuator is the sum of a set of components that exert force on the gas valve through the unloader. It consists of a valve chamber, a sealed chamber and an electronic control component device chamber. The valve chamber is a solenoid valve. And a return spring-driven two-position three-way valve, according to different positions of the solenoid valve, the piston of the actuator is subjected to pressure or atmospheric pressure transmitted from the hydraulic device, and the built-in small piston drives the unloader through the plunger of the sealing chamber . The electronic components of the HA are placed in the electronics compartment. These components control the solenoid valve, detect the hydraulic pressure and the temperature of the valve chamber of the intake valve. Each actuator is equipped with a microprogram processor that is processed by the microprogram through a specific program. The function of driving, detecting and communication is to install a temperature sensor in the sealed chamber. The detection point is close to the intake valve, and the measured temperature value can be sent to various state monitoring devices, thereby receiving the intake valve. The control status provides the basis for analysis and correction. In order to protect the moving parts in the device chamber and prevent the sealing parts from being damaged by high impact stress, a two-stage throttling device is arranged in the HA: the starting bypass chamber and an orifice plate are filled, and the bypass chamber is filled at the moment of the closing operation. When hydraulic fluid flows through the orifice, a high pressure is created, allowing the valve to cushion before it hits the valve seat. The hydraulic unit HU:HU is actually a hydraulic oil station. The pressure of the hydraulic oil is raised from the atmospheric pressure to the required pressure by the action of the pump, and the high pressure hydraulic oil is supplied to the HA to open the intake valve. Top dead center sensor TDC: In the HydroCOM system, the TDC transmits the instantaneous position of the piston in the cylinder, and HydroCOM calculates the time of the valve action based on the signal transmitted by the TDC. Compressor interface unit CIU: CIU acts to connect the HydroCOM system and DCS. The control output signal of each stage is converted into the signal of the opening and closing of the intake valve. The valve chamber temperature fed back by the HA is also transmitted through the CIU. On the DCS, the TDC transmits the crank angle pulse signal to the CIU at the same time to determine the time when the valve operates. The external power supply EPS supplies 48V DC power to the solenoid valve and electronic components of the HA. The isolation amplifier IA realizes the amplification of the TDC signal. On the CIU, the measurement module TIM delivers additional data such as exhaust valve temperature and pressure measured on site to the DCS. The server unit SU contains an IBM compatible machine and various service software based on the WINDOWS platform for analyzing the system and configuring the CIU. Once the system fails, the SU can establish detailed error analysis instructions about the CIU. Control scheme: Each stage of the compressor is equipped with a proportional integral controller. The first stage is controlled according to the process variable. The output of the first stage controller is mainly operated at the first stage, and the pressure between the stages can be selected as the latter. The control variables of each stage are transmitted to the CIU and converted into a 4-20 mA current control signal. The TDC transmits the actual position information of the piston in the cylinder to the CIU, and the CIU control signal is converted into the exact time when the intake valve is opened and closed. In this way, for the operator, the displacement of the compressor is only a simple analog control variable. With digital control technology, the HydroCOM system can open and close the intake valve only in 2 to 3 revolutions of the crankshaft. Regular resetting to meet different exhaust volume requirements. Application example The hydrogen production of the 600,000 t/a continuous reforming unit of Yanshan Petrochemical Company's refinery is about 30,000 m3/h. It is equipped with three reciprocating compressors with a capacity of 24,600 m3/h. If one of the compressors cannot be sent out, it will be opened. The two engines can not meet the processing capacity of the two compressors. In order to ensure the normal and smooth operation of the two compressors, the interstage reflow adjustment is used to optimize the pressure of the compressors by using the super-rapid and split-range control system. The surplus compression gas is returned to the intake manifold through the bypass regulating valve (PV2016, PV2038). As shown in the figure: the control scheme before the transformation can meet the requirements of regulation and control, but the control system is complicated and difficult to operate. When the machine is switched, the system pressure fluctuates greatly, and more importantly, it causes a great waste of energy (electric energy). In order to solve the above problems, we added a HydroCOM gas quantity stepless adjustment system in July 2005. When the control plan is selected, we require HydroCOM system to do: 1. Equipped with a set of HydroCOM on a constant start group. The system realizes 0-100% stepless adjustment, the other two are standby machines, 100% full load operation; 2. The main control variable of the HydroCOM system is the total inlet pressure of the unit, and the auxiliary control variable is the secondary total inlet pressure. These two pressures are also the pressure points strictly controlled by the continuous reforming re-contact system; 3. The HydroCOM system does not interfere with the original override control system, and the function of the HydroCOM system is to maintain the pressure of the first and second stage inlets of the unit. Stable, specific pressure setting value According to the needs of the process, the HydroCOM system should give priority to control. When the HydroCOM system fails, the HydroCOM system automatically cuts off, the unit runs at full load, and the system control is controlled by the original override and split control system. 4. For the convenience of operation, the HydroCOM system should have manual, automatic operation and system removal functions. The logic control function of the system is realized by the programming configuration in the existing DCS system. . Based on the above requirements, we have made appropriate changes to the original control system, as shown: after the transformation, the control scheme bypass control valves PV2016, PV2038 still play the role of flow regulation and pressure balance, but the HydroCOM system is preferentially adjusted, that is, the adjustment of the compressor The load controls the pressure of the re-contact system. When the HydroCOM system is removed, the pressure and flow of the re-contact system are still controlled by the original over-chirp and split-range control. Since the operation of the HydroCOM system, the operation has been smooth. From the perspective of the use of the whole system, the manual, automatic control and adjustment of the compressor load (discharge) between 0-100% can be realized by the hydraulic mechanism and the signal control system. Adjusting the flow rate of the compressor is simplified to input only the desired load or set pressure value, and the system automatically tracks and works. The system can make the whole control system of the compressor more reasonable, and can achieve smooth loading of the compressor. When the other two compressors are switched, the influence on the fluctuation of the system is relatively small. When the compressor starts, it has zero load driving, and the impact on the re-contact system and the power grid is relatively small. The various state parameters are more stable and effective. The load on the ammonia refrigeration system is reduced, which is also a useful complement to the existing ultra-sag control system. In addition, since the HydroCOM system was put into use, it has achieved high economic benefits. As shown, according to the current processing capacity of the device, 70t/h, the compressor load can meet the process requirements at 50%, and the annual calculation is 8000h. In the year of energy savings of about 3.5 million yuan, the economic benefits are very obvious. Bearing Chain,Steel Ball Bearing,Mini Ball Bearing Guanxian YX Bearing Co., Ltd. , http://www.sdbearings.com