In order to adapt to the environmental conditions of steam condensation water temperature in Guangfeng Cigarette Factory, which is generally about 70 C and pH 9-11, a new type of photoelectric level controller is designed and applied in practice.
The device realizes the functions of water level detection, signal transmission, control of pump motor and alarm at high and low levels. The device overcomes the existing mechanical type. The float valve and the float switch have the shortcomings of simple structure, high control precision and suitable for liquid level control of high temperature and corrosive medium. The daily recovery of steam condensate in Guangfeng Cigarette Factory is about 10 tons.
The condensate temperature is generally about 70 C.
The recovered condensate is filtered into the storage tank for boiler water. The purpose is to control the water level of the storage tank by using mechanical float level controller and float level switch successively.
It is found that this kind of water is used in the process of operation. The failure rate of liquid level control is high, which often results in overflow and low water level of reservoir. In view of this situation, the workshop needs to develop a new level control device to lower the level controller currently in use.
In view of the environmental conditions of steam condensate water temperature generally around 70 C and pH 9-11, a split water level control device is designed, which not only solves the problem that most of the liquid level controllers on the market are not suitable for medium level control with high temperature and strong corrosiveness. The device mainly consists of a water level indicator buoy, an upper limit optical controller, a lower limit optical controller, a control circuit, a low level acoustic-optical alarm and an electromagnetic valve controlled by a water inlet.
The liquid level indicator buoy includes: float ball, float ball guide rod, guide rail, thermostatic element light shield, water level calibration board and pointer.
The optical controller consists of power supply circuit, light control circuit connected with power supply circuit, high and low liquid level control line connected with solenoid valve opening and closing, and low liquid level alarm connected with sound alarm. A 15 stainless steel pipe is selected to weld 200 stainless steel ball at one end of the stainless steel pipe. According to the control range of water level, a 40 *30mm stainless steel sheet is welded on the stainless steel pipe as a light shield. After the buoy (see Fig.
1) is made, it is necessary to check the buoy leakage, so as to avoid the use of medium weld leakage and cause the buoy to float. A concave aluminium alloy part is used as a buoy moving guide rail, which is fixed on the top of the condensate backwater tank. The groove width of the concave aluminium alloy part is about 16 mm. Put the buoy into the concave aluminium alloy parts, and mark the liquid level height on the guide rail with the pointer. The upper and lower photoelectric switches and alarm photoelectric switches are respectively set on the guide rail according to the water level control range.
The compensation solenoid valve and the boiler feed water pump are controlled by the output signal of the photoelectric switch. The main working principle of photoelectric level control device (see figure 3): when the water level of the backwater pool rises, the floating ball floats to drive the floating ball guide rod upward in the guide rail, when the light shielding plate on the floating ball guide rod blocks the upper limit light controller, the photoelectric switch outputs signals, closes the electromagnetic valve for fluid replenishment, stops fluid replenishment and starts the boiler feed water pump at the same time. When the water level in the backwater pool drops, the float ball guide rod moves downward in the guide rail. When the shading plate on the float ball guide rod blocks the lower limit light controller, the photoelectric switch cuts off the electric signal, opens the replenishment solenoid valve, replenishes the solution to the container, and stops the boiler feed pump.
In order to prevent the low liquid level from affecting production, a low liquid level alarm light controller is installed on the guide rail. When the liquid level drops to the safety warning line of the equipment, the light shield on the guide rod blocks the low water level alarm light controller, the photoelectric switch outputs signals to the alarm, and the acoustooptic alarm alarm alarms to alert the operator. Operators indicate the height of liquid level by means of a calibration plate on the guide rail with a pointer mounted on the floating ball guide rod. The photoelectric liquid level control device overcomes the shortcomings of the existing mechanical floating ball valve and floating ball switch.
It has simple structure and high control precision. It realizes the accurate control of the water level of the boiler condensate backwater pool. From the installation and use situation, no condensate overflow and low-level situation caused by the control failure has occurred. The control device can select different materials to make buoys according to the temperature and corrosiveness of the medium used.