Application of the hottest PLC in the lubricating

2022-08-01
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Application of PLC in the lubricating oil system of taurus60 gas turbine

I. overview

programmable controller PLC has been widely used in gas turbine power stations. It uses the internally stored control program software and external input data and operation instructions to send instructions to the control device through logic and arithmetic operations to complete the control and adjustment of gas turbine generator units and auxiliary equipment

plc can control and adjust the engine speed, exhaust temperature, load of the gas turbine generator set, as well as the parameters and status of each engine system. For example, in the lubricating oil system, the control of parameters such as pressure, temperature and liquid level and the status of lubricating oil heater, lubricating oil cooler and AC/DC flow lubricating oil pump can be completed. This paper only introduces the partial application of temperature and pressure control in the lubricating oil system of taurus60 gas turbine

II. Introduction to the lubricating oil system of taurus60 gas turbine

see Fig. 1 for the installation position of temperature sensor RTD and pressure sensor tp380 in the lubricating oil system

III. PLC control of lubricating oil temperature

(I) PLC control principle

taurus60 gas turbine uses temperature sensor RTD to control and measure the temperature of steel ball lubricating oil system, and converts it into corresponding electrical signals, which are converted into digital signals through optical coupling and a/d conversion of input modules, and stored in internal memory. PLC scans internal application programs, reads data, and performs arithmetic and logic operations, Results the above control purpose was achieved by converting the output module to control the action of the actuator

(II) PLC control objective

the main purposes of controlling the lubricating oil temperature of taurus60 gas turbine are as follows: ① when the unit is shut down, start or stop the lubricating oil tank heater; ② During operation, if the temperature of the lubricating oil system is too high, start the alarm circuit and shutdown circuit, or send out audible and visual alarm or make the gas turbine emergency stop; ③ Control the start, stop and speed of the cooling fans of the three oil radiators of the oil system, so as to control the oil temperature of the oil system, so as to keep it within the specified range. It plays an important role in guiding industry development, promoting industry self-discipline, improving technical level, enhancing international exchange, expanding utilization cooperation, and expanding publicity and promotion

taurus60 gas turbine unit has two oil temperature sensor RTDs, namely, oil tank RTD (rt390) and oil pipe RTD (rt380). The oil tank RTD is installed in the oil tank to sense the oil temperature of the oil tank. When the oil temperature of the oil tank is lower than the set value (65 ℉) (18 ℃), the PLC commands the oil tank heater to start to heat the oil; When the oil temperature in the oil tank reaches the set value of 70 ℉ (21 ℃), the PLC commands the oil heater to stop running. The lubricating oil pipe RTD is installed on the main lubricating oil pipe to sense the system lubricating oil temperature. When the system temperature is higher than the set value of 160 ℉ (71 ℃), the alarm circuit will start to alarm; When the system temperature rises more than the set value of 165 ℉ (74 ℃), start the emergency shutdown circuit of the gas turbine, and the gas turbine stops running

plc can also control the operation of the oil radiator. When the system temperature is higher than the set value of 100 ℉ (38 ℃), PLC commands the cooling fans of 1 ; When the system temperature is lower than the set value of 90 ℉ (32 ℃), the PLC commands the cooling fans of 1 . 1 12\2\oil radiator fan is operated by PLC to control the output of fan frequency converter according to the system temperature, so as to realize the smooth speed regulation of oil cooling fan, so the adjustment of oil temperature is very accurate; When the oil temperature exceeds 140 ° f (60 ° C), start the 3# radiator fan, which is controlled by the relay

(III) PLC control process

limited to space, we only take the alarm and shutdown of taurus60 lubricating oil system caused by high lubricating oil temperature and the startup and shutdown of 33oil cooler fan as examples to discuss how PLC controls the lubricating oil temperature

plc is controlled by ladder language

1. control procedure for alarm and shutdown caused by high oil temperature when the oil pipe temperature is higher than 160 ℉ (71 ℃), high oil temperature alarm will appear, which will attract the attention of maintenance personnel; When the oil temperature is higher than 160 ℉ (74 ℃), high oil temperature shutdown will occur to ensure the safety of the equipment

2.3pppppp> the start or stop command of the oil cooling fan is enabled when the oil pipe temperature is higher than 100 ℉ (38 ℃) or lower than 90 (32 ℃). Specifically, when it is higher than 100 ° f (38 ° C) or lower than 90 ° f (32 ° C), the start (or stop) command of the oil cooling fan is input through the output module (as shown in Figure 3)

when the oil temperature exceeds 140 ℉ (60 ℃), the control circuit circuit of the 3cooling fan start timer acts (as shown in Figure 4). At this time, the relay K coil is energized (or de energized) and its normally open contact is closed (or disconnected), the contactor k4983 coil is energized (or de energized), and its normally open contact is closed (or disconnected) and connected (or disconnected) to the 3oil cooling fan. (as shown in Figure 5)

IV. oil pressure control

(I) PLC control principle

oil pressure is realized through oil pressure sensor tp380 (hereinafter referred to as tp380), input and output module, PLC operation, etc. Tp380 senses the lubricating oil pressure varying within the range of 0 ~ 690kpa and converts it into a 4mA ~ 20mA current signal. The input and output module converts the current signal into a digital signal for PLC recognition. After calculation, PLC stores the result in the ground unit marked as lubepress for program call

plc control target taurus60 gas engine has three sets of oil pumps, namely, main oil pump, AC oil pump and DC oil pump. The main oil pump is driven by the gas turbine to provide lubricating oil for the gas turbine and generator and pressurized oil to control the action of the actuator; AC lubricating oil pump is used to provide pre operation and post operation lubrication for gas turbine and generator. Therefore, whether its size control can play a very important role in terms of printing quality and printing speed within appropriate limits. When the main lubricating oil pressure is lower than the set value, it will be started in an emergency to ensure the normal operation of gas turbine; As the standby pump of AC lubricating oil pump, DC lubricating oil pump shall ensure the lubrication of gas turbine in case of AC lubricating oil pump failure or power loss of the whole gas turbine power station

after the start-up cycle of the gas turbine, the PLC first tests the DC lubricating oil pump. When the pressure of the DC pump p903 reaches 4psi, the PLC cuts off the power of p903 and starts the AC lubricating oil pump bp321. If the pressure reaches 6psi, the PLC allows the gas turbine to run. The lubrication timer starts counting before the PLC starts. The gas turbine must be lubricated for 30 seconds at a pressure greater than 6pis, If the lubricating oil pressure is lower than 41pis, PLC will give an alarm of low lubricating oil pressure. If the lubricating oil pressure is lower than 25psi, start the quick shutdown without locking. Under the stable operation condition of the gas turbine, the oil pressure is adjusted by the oil pressure and temperature control component, but the PLC always monitors the change of the system oil pressure, and completes the low oil pressure alarm, starting the AC oil pump, starting the quick shutdown without locking, etc. under different states. When the gas engine stops running, the PLC checks the operation of the DC pump. When the 30 second timer starts, the lubricating oil pressure is allowed to drop to 3psi, the timer ends, the AC lubricating oil pump is switched on again, and the lubrication starts after the operation. These are completed by the control program preset by PLC

plc has prepared five different post operation lubrication schemes for use according to different operation and shutdown conditions of gas turbine

(II) PLC control process

here we only introduce the pressure calculation of the lubricating oil system and the command program for starting the DC pump

1. calculation of oil pressure input data, as shown in Figure 6

2. DC lubricating oil pump

start command enable DC lubricating oil pump is the standby pump of AC lubricating oil pump. When AC pump or tp380 fails, DC lubricating oil starts. The command enable is shown in Figure 7

v. conclusion

plc is very complete in controlling the lubricating oil system, and its control contents and items are also very complex. It can not only control and display the pressure and temperature in the lubricating oil system, but also set the limit value of pressure and temperature. Once the system exceeds this limit value, it can give an alarm signal or stop the system operation to ensure the safety of the equipment; It can also control the operation of the oil tank heater, control the level of the oil tank, and give an alarm signal. Limited by space, we can only extract a small part of its capital operation to promote the smooth operation of the enterprise, and make a brief introduction, hoping to have a certain reference value for the control of the lubricating oil system of large and complex equipment. (end)

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