Acid Dilution System

Description

The proposal is dedicated to the acid dilution system, mainly used for the preparation and cooling of dilute acid solution.

The acid dilution system has designed capacity: the electrolyte preparation of 1m³ / hour.

The acid dilution equipment can transport diluted acid to the designated sulfuric acid storage tank; the equipment also comes with display of acid density and acid temperature.

It is automatic online acid dilution system, with automatic online density checking process.

Process

1. Concentrated acid (Prepared by the user)

1.1 Concentrated acid unloading

Park the acid transport cart near by the concentrated acid storage tank, after setting the specified concentrated acid storage tack 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 electronic weight scale of the concentrated acid storage tank is always showing the weight of concentrated acid, and if its weight reaches the preset weight limit, it will send sound and light alarm at the same time. Close the concentrated acid electric valve of the tank and stop feeding acid into the tank; The concentrated acid storage tank is equipped with electronic liquid level gauge and upper and lower limit liquid level display device. When the concentrated acid liquid level reaches the upper limit position, it will also alarm with sound and light and close the concentrated acid electric valve to stop the acid feeding into the tank. Double protection to ensure acid does not spill. All concentrated acid pipes are double layer pipes and equipped with leakage detection and alarm system.

Considering the accuracy of the weighting, all inlet piping and outlet piping of the concentrated acid tank adopts soft connection.

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, the target dilute acid density to be prepared is converted to the percentage concentration by weight through table lookup, input the weight percentage and the total weight of the desired dilute acid on the touch screen (total volume 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 in the automatic mixing and cooling device. Each unit has a separate concentrated acid buffer tank.

Regarding concentrated acid added into the automatic online acid dilution system, it is controlled 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 value, the PLC sends the signal, the concentrated acid pneumatic valve automatically closes, the concentrated acid pump also automatically shuts down.

2. DM Water

Acid dilution system comes with a DM water supply system. With a 5m³ water tank (including electronic level gauge), one pure water pneumatic valve and one set of DM water to automatic online acid dilution system to connect pipelines and valves. When the DM water level reaches the set value, the PLC sends the signal, the DM water pneumatic valve automatically closes, the DM  pump also automatically shuts down.

3. Acid Mixing

3.1 Principle of acid mixing：

Start the acid dilution "Run" button, pneumatic valve of cooling water, cooling water pump (including cooling tower fan), according to the PLC to calculate the concentrated acid and additive amount of pure water, the electromagnetic flow meter and pneumatic control valve will control the flow velocity, flow into the graphite condenser by gravity for mixing and heat exchange, the cooled  dilute acid will flow into the density fine adjustment device. When the concentrated acid and pure water reach the addition quantity, stop the initial ratio and cooling cycle, and pump them to the density fine adjustment device for fine adjustment to the target density.

The density fine-adjustment device is equipped with two temperature monitoring points: when the temperature is too high (≥ 80 ° C), the concentrated acid pneumatic valve which connects concentrated acid buffer tank and the graphite dilution condenser will automatically close to stop adding acid; when the temperature drops below the set temperature (≤ 60 ° C), the pneumatic valve automatically opens to continue to add acid. The other measurement point is set near the entrance of the circulation acid in the density fine-adjustment device. The difference between the two temperatures reflects the efficiency of the cooling heat exchanging. 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 pump and cooling tower will also stop running.

3.2 Each set acid dilution system contains one set of online acid mixing device, one set of the density fine-adjustment device; two sets of temperature control device; one set of system piping and valves.

3.3 Various processes running status, each parameter setting, 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 of dilute acid tank is equipped with one set of electronic level gauge, one set of visual liquid level, overflow acid pipe and overflow tank (with overflow sound and light alarm device).

5. Control section

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 selection of acid mixing equipment, the system will prepare the target acid in accordance with the set parameters. The process is fully automatic.

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 low level and high level display, acid tank temperature, liquid level inside the acid mixing tank, all pumps and valves’ start or stop status).

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.