Acid dilution system
1. Concentrated acid
1.1 Concentrated acid unloading
Park the acid transport cart near by the concentrated acid storage tank, after setting the specified concentrated acid storage tank on the touch screen., press the run button. The corresponding valve will automatically open. At the same time, the storage tank breathing valve will open automatically. The concentrated acid will be pumped into the storage tank. The electronic scale on the tank will display the weight of the acid at all time. Once the weight of the acid reaches the pre-set weight limit, an alarm with blinking light will sound. At this time, the valves will automatically close and stop pumping acid into the storage tank. The tank is also equipped with an electronic level meter display apparatus having upper and lower level limits. When concentrated acid level reaches the upper limit position, the sound and light alarm will sound and turn off the valve. The double protection on the equipment ensures the concentrated acid does not overflow. All concentrated acid pipes are double tube and equipped with leak detection alarm system. Considering the accuracy of the weighting, all tubing and piping in/out from the tank are soft connections.
1.2 Concentrated acid transport
The principle of Automatic acid dilution is mixing according to the mass (hereinafter referred to as weight) percent concentration: first, find out the target weight percent concentration by converting target dilute acid density using conversion chart. Then input both weight percent concentration, and the total weight of the diluted acid you are targeting, in the touch screen (total volume you want, must be 5m3), the PLC will automatically calculate the volume of pure water and the volume of the concentrated acid required for such solution. Acid from the concentrated acid storage tank will then, be delivered to the concentrated acid buffer tank on the online mixing and cooling devices. Each unit has a separate concentrated acid buffer tank. The concentrated acid buffer tank equips with an overflow tank to prevent spills in case of any control that does not work properly.
Specific to which online mixing and cooling unit the concentrated acid is sent to, is control by the corresponding pneumatic valve. Each pneumatic valve is in series with a manual valve, for easier maintenance access to the pneumatic valves later on. All concentrated acid pipes are double protected, and is equipped with leak detection alarm system.
When the concentrated acid level reaches the set point, PLC signals the pneumatic valve to close automatically; concentrated acid pump will also shut down automatically.
2. Pure Water
Acid dilution system comes with a pure water supply system. With a 5m3 water tanks (including electronic level gauge); water pneumatic valve; one set of connecting piping and valves to online mixing and cooling unit. When pure water level reaches set point, PLC signals, pure water pneumatic valve closes automatically, pure water pump automatically shuts down.
3. Acid Mixing
3.1 Principle of acid mixing
Start equipped acid "run" button, pneumatic valve of the cooling water, cooling water pump (including cooling tower fan) starts. PLC calculates the dosage of concentrated acid and pure water, with electromagnetic flow meter and pneumatic control valve to control the flow rate. The gravity flow into graphite dilution condenser, carry out mixing and heat exchange. The chilled diluted acid will then, enter the proportion fine-tuning device. When the concentrated acid and pure water reaches the set amount of dosage, early ratio and cooling cycle stops, the proportion of fine-tuning device will fine-tune to the target value.
The proportion fine-tuning device equipped with two temperature monitoring points: when the temperature is too high (80° C) concentrated acid buffer tank to the graphite dilution condenser concentrated acid pneumatic valve will automatically shut down to stop adding acid, pneumatic valve automatically opens when the temperature drops below the set temperature (60°C), continue to add acid. The other measurement point is set near the entrance of the cyclic acid, in the proportion of fine-tuning device. The difference between the two temperatures reflects the efficiency of the heat exchanger. When the temperatures of the two monitoring points are both lower than 40C°, the mixing is complete. Circulation pump, cooling water pneumatic valve closes automatically. Cooling water pumps and cooling towers will also stop running.
3.2 Each set with acid dilution system contains one set of online acid mixing and cooling unit, one set of the proportion of fine-tuning device; two sets of temperature control device; one set of system piping and valves;
3.3 Various processes running status, each parameter settings, display and control, all done by touch screen.
4.Acid output section
4.1 Each target acid from acid mixing device can only be delivered to the specified dilute acid tank.
4.2 Each group the dilute acid tanks are equipped with one set of electronic level gauge, one set of visual level, overflow acid pipe and one set of overflow tank (with overflow sound and light alarm device).
5.1 The control section uses the combination of the PLC + touch screen. Through the touch screen, we can set the equipment operating parameters. Parameters such as weight percentage concentration of target dilute acid and dilute acid total weight, can be input to the touch screen. With the choice of acid mixing equipment, the system will prepare the target acid in accordance with the set parameters. The process is fully automated.
At the end of the target acid preparation, the diluted acid can be delivered to the designated dilute acid tank.
5.2 Real-time display of various equipment operating status (such as level low and high, acid weight in the concentrated acid storage tank, acid tank temperature, liquid level with the acid tank, pumps and valves to start or stop)
5.3 Each process within the system has interlock control. Any electronic level gauge reaches the upper limit position, there will be sound and light alarm, and at the same time all corresponding electric valve will close and all related equipment will stop.