TANK truck cleaning has become increasingly sophisticated in recent years. It is important to choose the right equipment for the operation and make sure the machinery is properly maintained and repaired.
The equipment side of the business was addressed by a number of speakers during the National Tank Truck Carriers Tank Cleaning & Environmental Council annual seminar held April 4-5 in Austin, Texas. Topics covered included on-demand boiler technology, cleaning vat efficiency, and pump maintenance.
Many wash racks could gain greater efficiency in generating steam and hot water by switching to on-demand boilers, according to Mike Algermissen, Miura North America Inc. These units are modular, which makes it much easier to accommodate wash rack expansion. Each on-demand unit generates double the steam output compared to a conventional boiler while occupying half the space.
“On-demand boiler systems reduce energy consumption required to meet the sort of variable steam demand found in most wash racks,” Algermissen said. “Modular systems can be customized to meet the variable loads at a specific wash rack.”
Radiated heat loss is significantly less for an on-demand boiler than for a conventional boiler. Modular on-demand boilers maintain high in-service efficiencies — in the 81% to 83% range compared with a conventional boiler.
In addition, the modular units store much less water than conventional boilers. For instance, each Miura 200-horsepower unit stores 65 gallons, compared with up to 1,000 gallons in a conventional boiler. “Less stored water means greater safety in the event of a catastrophic failure,” Algermissen said.
On-demand boilers are easier to service and maintain, according to Chris Robison, Burner Combustion Systems. For one thing, Miura units have no moving parts. As with any boiler, scale buildup is one of the biggest efficiency killers. Scale with no more than eggshell thickness will cut boiler efficiency by more than 10%.
“The Miura units address the scale issue with the only built-in scale detection system in the industry,” Robison said. “Attached directly to the boiler tubes, the detection system samples feed water every 30 minutes and can detect water hardness below one part per million.”
Managers for a couple of the tank wash racks that are using on-demand boilers reported that the equipment is working well for them. Joe Brown, Hoyer Global (USA) Inc, said the on-demand boiler system helped the company's wash rack in Pasadena, Texas, address a NOX issue, and the system delivers virtually unlimited amounts of steam. However, water treatment is a critical factor to ensure that the system functions properly.
Marcel Pouliot, Trimac Transportation Inc, said four of eight Trimac wash racks in Canada have been fitted with Miura on-demand boilers. He said the carrier saw a six- to eight-month payback with the system, but echoed the caution regarding water quality.
“Water quality is extremely important with these units,” he said. “Hard water will damage the burners.”
Cleaning vats
A high percentage of tank wash racks use vats containing water and wash solutions that are recirculated during the cleaning process. Good vat performance starts with an effective design than can be maintained with minimal effort.
“How a vat is constructed and managed will affect the life and performance of the chemical solutions used in the tank cleaning process,” said Marlin Moser, A-ONE Chemicals and Equipment. “Size and shape matter. Is the vat round of rectangular?
“How hard is the vat to clean? I've seen very few that have side-mounted manways for access to clean out solids. How hard is it for workers to access and clean the strainer screen in the vat? Vats need an effective way to skim oils off the top of the recirculated cleaning solutions.
“What sort of heating system is in the vat? Heating coils are the norm and should be set to maintain temperatures between 165°F and 180°F to minimize foam in the cleaning chemicals. Do your workers know if the cleaning solution is hot enough?
Good vat management must include a process for monitoring cleaning chemical consumption. “Wash rack managers need to be disciplined and diligent in monitoring cleaning chemical use,” he said. “You need to know where your cleaning chemicals are going to control operating costs. Keep good logs of cleaning chemical use, and limit the number of workers who handle the chemicals.”
Pump maintenance
Pump downtime plays a critical role in wash rack profitability, according to Bart Smith, Valley Equipment Co. “How many trailers are you unable to clean when critical pumps are down?” he asked. “How much do you pay in overtime and other worker expenses? How much does shipping and expedited freight cost?”
Getting pumps back on line quickly takes planning and preparation. First of all, wash rack managers need a complete parts list for every pump. They need to know pump and motor sizes.
A key to success for any pump maintenance program is a stockpile of critical components. These include pump packings, seals, and couplings. Motors and power frames should be part of the stockpile. Other critical components include impellers, shafts and sleeves, bearings, and gaskets.
“Your pump vendor can supply a detailed list of critical parts for each type and model of pump you operate,” Smith said. “Standardizing the pumps used in the wash rack is one way to limit the number of critical parts that must stockpiled.
“Going beyond the challenges of responding to pump failures, wash rack managers need to develop good preventive maintenance programs. A pump that isn't maintained will fail. Pump vendors and manufacturers can help by providing detailed guidelines for preventive maintenance.”
Maximizing pump uptime starts with specifying the correct equipment for the job. Next, pumps and hardware must be installed correctly. For instance, correct drive coupling alignment is critical for a long, trouble-free pump life. Make sure the pump motor has the correct oil and that the motor is turning the pump in the right direction.
Pressure gauges must be installed properly and be maintained. “Once pumps are installed and put into operation, the pressure gauges are often forgotten,” Smith said. “These gauges give you a good indication of how your pump system is operating.”
Wash rack maintenance workers need regular training updates on pumps and other equipment. Maintenance workers also need the right tools to troubleshoot and repair pump systems. ♦
