1. The Manual Method. A worker physically cleans a tank and may actually enter it to do so. This raises safety concerns and often results in inconsistent cleaning, as well as the use of more cleaning chemicals and water than is really necessary.
2. The Fill & Drain Method. Tanks are usually hosed down and then filled with water and cleaning/sanitizing agents. This method is time-consuming and utilizes significant amounts of water, cleaning chemicals and energy, while also keeping tanks out of production for several hours.Many plants find they can save tens of thousands of dollars annually by automating tank cleaning processes. Determining if you could benefit similarly through automation begins with a close look at your cleaning objectives.
The second step is to identify a cleaning liquid. The cleaning liquid will react with the product residue to physically wash it away or dissolve it. Once the cleaning liquid is identified, consider temperature and material compatibility requirements. This will be important when selecting the tank wash nozzles/system for your application.
The third step is to determine what level of cleaning is required. Once you’ve established your cleaning objectives, you can begin the process of selecting the right automated solution for your operation.
CIP systems can be configured with a wide variety of spray balls or nozzles, so it is important to understand the various operating methods and resulting performance.
CIP Or Portable Motorized Tank Washers
Motor-driven tank washers use solid stream nozzles and operate at pressures from 100 to 4,000 psi (6.9 to 276 bar) to remove stubborn residue. The motor, air or electric, drives the nozzle assembly with two to four nozzles revolving around the central axis of the nozzle assembly. Motorized tank washers offer independent control of the liquid pressure for cleaning, and the rotational speed (cycle time) to optimize the cleaning process.
Motorized tank washers can be taken from tank to tank or permanently installed. The distance between tanks, cleaning cycle frequency, the number of tanks, the flow system design and labor availability are key considerations when choosing between portability and permanency.CIP or portable motorized tank washer advantages include:
- High-impact force for cleaning even the toughest residue.
- Requires less water for effective cleaning.
- Accommodates a wide variety of nozzles for use with multiple tanks.
- The units are lightweight and can be moved from tank to tank if desired.
- If CIP is preferred, multiple mounting options are available, including a sanitary tri-clamp flange.
- The spray head fits through small diameter tank openings.
- Multiple shaft lengths are available to accommodate a wide range of tank sizes.
- As with any mechanical device, maintenance is required.The need for a separate motor instead of using only the cleaning liquid to rotate the nozzle.
- Debris in the water is a hazard, so filtration may be required.
- These units are usually priced higher than fixed spray nozzles, fluid-driven reactionary force, and constant speed nozzles.
- Some motorized tank washers offer a higher level of automation if the units can be permanently installed in the tank. Designed for use with tanks up to 40’ (12 m) in diameter, these units include a pneumatic retraction mechanism that lowers and raises the tank washer from the tank. Manual lifting of the unit is eliminated, as is clogging that can result from the nozzles being left in the tank when not in use.
Fully Automated Cleaning Systems
Automated tank cleaning systems offer many benefits:
- Standard pump/motor sets are sized for best operating efficiency and optimal performance of tank cleaning nozzles.
- Repeatable tank cleaning performance that facilitates regulatory compliance and ensures operator safety.
- Precise control of cycle times ensures cleaning objectives are achieved in the shortest cycle time, conserving energy and water.
- Pushbutton system management. Cleaning cycles and multiple cleaning routines can be adjusted and activated more quickly and easily. Labor requirements for system set-up, operation and maintenance are minimal.
- Automated chemical injection. The correct amount of chemical is injected consistently, ensuring cleaning effectiveness and preventing the waste of costly chemicals.
Cleaning Validation Options
Rotation speed and frequency, spray loss, nozzle clogging and pressure variation are monitored using diagnostic software, and audible and visible alarms notify operators when changes are detected. Detailed documentation is sent from the monitoring device to a PC for quality control and record-keeping purposes.
Acoustic monitoring devices are typically compatible with pressurized and non-pressurized tanks of all sizes, and can be used with a wide range of tank wash nozzles and motorized tank washers.
In some instances tank cleanliness is validated by coating the tanks with proteins or other substances that fluoresce under UV light. Taking cultures with swabs to verify tank cleanliness is another common approach.
Less typical is measuring the conductivity/resistivity of the water/cleaning agents or analysis of the final tank wash effluent in order to determine if contamination is present.
Automation Can Pay Off Quickly
However, low-pressure CIP systems are quite economical since the cost of spray balls and nozzles is very reasonable. Motorized tank washers and automated tank cleaning systems are more costly but typically offer a quicker return on investment.
Many users of automated tank cleaning products and systems report a payback period of just a few months. The gain in production uptime and the reduced labor cost comprise most of the savings. The reduced cost of chemicals, water, energy and wastewater disposal also add up quickly and contribute to the short payback period.
Is automated tank cleaning for every manufacturer? In most instances the answer is yes. However, it is important to thoroughly research all the automation options available to ensure you will achieve your tank cleaning objectives as efficiently and economically as possible.
Christine Pagcatipunan is an applications engineer at Spraying Systems Co. As the company’s tank cleaning expert, she analyzes and customizes automated tank cleaning solutions.
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By Christine Pagcatipunan Process improvement and cost reduction are key motivators for any plant. As a result, automated tank cleaning is increasing in popularity.