Innovations in chemical transfer technology

Bennett provides some thoughts on current developments and future trends in the industry with the focus being on efficiency and the environment.

Figure 4. Vogelsang rotary lobe pump installation (Courtesy of Vogelsang). 

We asked our contributors what aspects of chemicals storage, handling and transfer their companies are involved with, and which of these are currently their main areas of activity.

Vogelsang told us it operates in the oil, gas and chemical industry with the current focus being on transfer. This involves loading and emptying mobile units such as tankers, trains or ships, as well as fixed tanks on industrial sites.

“We handle media with a high solids content without any problems such as waste oils or viscous and chemical aggressive media, paints, soaps, adhesives and glues, natural latex, pesticides, resins, cosmetic raw materials, acids and bases, oils or a hydrocarbons mix,” Harald Vogelsang at Vogelsang explained.

“We also provide pumps for use in wastewater treatment processes within chemical plants where we can manage the abrasive waste from these processes without any difficulty.”

Netzsch say that they also provide pumping solutions for all the above mentioned applications in the environmental sector, the marine industry, chemical and process industries in general and in the oil & gas industry. With their broad range of progressing cavity pumps, rotary lobe pumps and multi screw pumps they also cover a wide range of applications in the food & beverage industry or for the production of cosmetics, paints, pulp & paper and many more. The company is also involved in providing technology for mining, where there are many aggressive chemicals, abrasive sludges and other critical media to be dosed and transferred.

Figure 3. Tornado T2 rotary lobe pump (Courtesy of Netzsch).

New concept

Polyflx has developed a new concept of dilution pump, initially used in Glencore Nikkelverks online auto samplers. This pump dilutes, very accurately, up to a 1:200 ratio with no waste of thinner during sample flushing. There are potential applications in a number of industries.

“The concept can be made to measure and mix as many liquids as you like in a very simple and accurate manner. The mixing ratio of all liquids can be adjusted mechanically or electronically and during operation.” Loyd Arve Nornes of Polyflx explained.

Vogelsang’s innovation policy focuses on two main priorities. “The first is pumping more demanding and complex mediums,” explained Mr Vogelsang. “The second is to reduce the pumping cost of the installation, making our technology as attractive as possible. That means simplifying the maintenance requirements, promoting energy efficiency and increasing the life of our products and components, for example with innovations like our patented Injection System.”

Recent research and development priorities besides ongoing process optimization advised by Netzsch included service and maintenance friendliness for the operator, minimizing the mean time to repair, implementing full service-in-place technologies as well as focusing on energy efficiency and environmental care.

“To challenge myself I built a biodiesel plant in my garage. This was fun, but making biodiesel did not satisfy my curiosity. I decided to develop my batch biodiesel process into a continuous process, said Mr Nornes.

Continuous flow

To obtain a continuous flow of vegetable oil containing 14% methanol was challenging. Mr Nornes concluded that either the batch process or an advanced circuit containing two pumps, two electric motors, two flowmeters, one controller and at least one control valve were required. What was needed was a much simpler solution.

After significant research and development Mr Nornes came up with an innovative solution - a piston ring with a plunger installed through it. The plunger stroke is always the same but the piston stroke can be adjusted by moving the pump housing away from or closer to the motor. This makes it possible to easily adjust the mixing ratio.

The flow rate can be adjusted with the speed of the motor. It is a very simple design. The first pump Polyflx made consisted of only 20 parts, including balls and springs in the check valves. After reading about the concept in Norway’s Teknisk Ukeblad magazine, the person with responsibility for developing new process analysis in Glencore Nikkelverk AS in Norway called Polyflx and asked if it could develop a different version of the pump for its auto samplers.

He had a problem with sample dilution using peristaltic pumps. The peristaltic pump could not give an accurate dilution due to changes in pump tubes over time. The pump he needed was a challenge to make because the sample dilution required was 1:200 and the solution to be sampled was very corrosive.

The result was a pump unlike anything Polyflx had considered when developing the concept but it still used the same principle. Made of titanium and PVDF (see Figure 1), the pump has good repeatability. The concept is patented in Norway and international patent applications are pending.

Figure 2. Pump installation on a mineral slurry application (Courtesy of Netzsch).

Blend ratio

This new innovation, the Polymeter pump is an entirely new way of measuring and mixing two or more liquids to create a consistent result. It integrates piston and plunger action pumps in the same chamber and allows for total control of the blend ratio between the liquids. From separate reservoirs, the pump accurately and fully automatically blends the liquids into a final product.

Glencore has not completed the testing but Mr Nornes is very satisfied with his internal tests. In addition to being precise, the pump has been programmed to flush the sample without any use of thinner.

“To get a fresh sample, a minimum use of thinner is a bonus. This pump will improve process analyses when there is a need for accurate and precise dilution,” Mr Nornes said.

Polyflx is focusing on reducing waste and improving precision and repeatability. Its pump delivers a 30 ml diluted sample to an online analyzer four times every hour.

“The design of this challenging dilution pump took most of our time initially but we are now ready to further develop the original idea to make a low pressure, high volume, metering pump to replace the more established continuous process or a batch process,” said Mr Nornes.

Polyflx has been funded by Innovation Norway to develop this pump in cooperation with a demanding customer. They are looking for a partner who believes in the solution.

“The customer pays for the pump and Innovation Norway pays for the development,” said Mr Nornes. The customer gets a pump specifically designed for their needs and only commits to buy one pump. We are also open for cooperation with an established pump manufacturer to push this product to market.

“The Polymeter gives you complete control of the final product and promises precise results with every use. It can be scaled and fitted to exact specifications.”

Mineral slurry

One of the processes involved in the mining of gold and silver requires the concentration of mineral slurry, essentially dewatering a mixture of mineral ore and water. Once the mineral slurry is concentrated, it must be pumped to the next phase of processing, normally leaching.

At a large gold and silver mining operation in northern Mexico, the customer was having problems optimizing the transport of slurry from its dewatering process, causing major problems for pumps involved in the operation.

The customer needed to achieve a concentration of 60% mineral solids in the slurry. The problem they faced was that the centrifugal pumps transporting the decanted slurry were not able to pump slurry with a concentration above 30%. As a result, the mine operator had to re-inject water back into the slurry to make it fluid enough to pump, after just using energy and chemicals to dewater it in the decanting process.

Also, the centrifugal pumps required constant maintenance and a complete change-out after only three months of operation. Slurry with a lower concentration of minerals also requires costly dewatering in the next phase of processing and a more fluid slurry contains less gold and silver, leading to lower plant optimization.

Looking for a solution to the problems with centrifugal pumps, the customer tried out another pump type. However, after two days of operation the pump housing was destroyed. At this point Netzsch was contacted through a distributor to try to solve this production problem.

“When I first learned about the slurry concentration the customer was looking to pump, I wasn’t sure if we could achieve that,” said Antonio Castilhos of Netzsch. “However, I knew if we could get the customer to a higher concentration of minerals in the slurry, they would be able to produce more silver and more gold per hour, at a lower cost. So we decided to take a look.”

Production testing

Netzsch began production trials at the mine with a stock progressing cavity pump. The production testing began with the same slurry mixture of 30% mining solids that was currently feeding the centrifugal pumps. Throughout the trials, the water content in the slurry was constantly lowered until the water injection was stopped altogether, with the Netzsch pump able to pump slurry of up to 65% of minerals solids.

“We were able to pump the slurry without any injection of water and the customer told us that this level of performance would pay for the cost of the pump within two or three hours of operation,” Mr Castilhos explained.

Additionally, with less water in the slurry, leaching, the next processing phase, would be able to use a lower volume of aggressive chemicals saving the customer money and benefiting the environment.

Following a successful trial, final specifications for the production pumps were determined. For this slurry pumping application, a Nemo NM series pump was specified using a tungsten carbide rotor and a Nemolast S61M with superior abrasion resistance stator. A variable frequency drive was also used to verify the best operating speed during the tests. Pump rotation was initially 189 rpm with a 20 HP motor, but after testing, the best rotation was determined to be 130 rpm.

The Netzsch progressing cavity pump product line is built for difficult applications with an enlarged stuffing box and tapered suction housing that results in more efficient operation. The pump is self-priming, has a low shear rate on pumped fluid and is built for handling highly viscous fluids with solids content.

“Three slurry lines with our progressing cavity pumps are now operational at the mine and the customer is seeing bottom-line operational and life cycle cost benefits,” Mr Castilhos said. The installation is shown in Figure 2.

“Not having to inject water back into the slurry saves on costly chemical processing in the leaching operation. From a life cycle cost perspective, the mining operation has dramatically lowered the maintenance and replacement costs associated with the earlier centrifugal pumps,” added Mr Castilhos.

“Even with the abrasive nature of the slurry, the rotor and stator in the Netzsch pump are lasting three months before requiring replacement. And, with plant uptime improved, more gold and silver ore can be processed, leading to an improvement in overall operational profitability.”

Cost factor

A substantial cost factor is attached to chemical transfer where emptying, transporting, dosing and filling are some of the core processes. To meet growing pressure to achieve efficiency in this area, Netzsch has developed the Tornado T2 rotary lobe pump (see Figure 3).

Pumps in the processing industry must operate in a pressure-stable, constant and smooth way but at the same time they should also be low maintenance and have reasonable operating costs. Positive displacement pumps proved their worth in a variety of fields of application. They achieve high pumping capacities, are self-priming, resistant to dry-running and convey without strong pulsation or shear forces.

They are suited to low to high viscosity, abrasive media, either containing solids or gases, lubricating or non-lubricating. It was essential to keep these typical characteristics when reworking the pumps and also to increase efficiency still further through design modifications.

Reversing the materials in the pump chamber represents a crucial innovation at the rotary lobe pump. So as to be equipped for challenges of this kind, the whole materials concept of conventional rotary lobe pumps was reversed when the TORNADO® was redesigned: two lobes made of hardened steel are used, which rotate in a geometrically adapted elastomer insert, instead of the standard elastomer lobes.

Bi-lobe rotors here have the advantage that the sealing line to the housing is considerably longer and therefore more wear padding is available. A specially developed pulsation reduction system ensures that hardly any pulsation or shear forces are generated, despite the straight, bi-lobe rotor design.

Elastomer inserts are vulcanised onto the edges of the lobes, so that there is a permanent hard-soft contact between the lobes throughout the 360° rotation cycle. This avoids high-wear contact between elastomer parts. The elastomer insert as a stator is subject to considerably less dynamic load and deformation than previously when functioning as a rotor. This means energy is saved, wear is reduced and the service life of the pump is increased overall. 

Furthermore, the drive was radically modified and the complex timing gear was re-placed by a robust synchronised gear with belt drive. This means that not only is the danger of transmission damage greatly reduced, but the weight and installation space required are also lowered. In addition, this drive requires no lubrication, so there is absolutely no chance of any oil leaks. If repairs or maintenance measures are nevertheless necessary, conveying and gear chambers can easily be opened. The cover and attachment of the components are laid out in such a way here that you can access all areas freely and every part can be replaced with standard commercial tools in just a few minutes

Tanker transfer

“As far as the transport and logistics sectors are concerned, our rotary lobe pumps are particularly well suited for installation in tankers,” explained Harald Vogelsang of Vogelsang, an internationally operating engineering corporation with its headquarters in Germany. The company develops and produces equipment and systems for pumping, shredding and distribution technology used in agriculture and the biogas industry as well as for industrial and municipal applications.

“Our rotary lobe pumps meet the special requirements of this vehicle group: the flow direction can be reversed, they are compact, have a high capacity and are easy to service. The compact design makes our rotary lobe pump ideal for installation in tankers, where space is limited,” he added.

Once installed (see Figure 4) the pump can be serviced directly in the vehicle, easily and quickly and without having to be removed. As its flow direction can be reversed, the pump can both fill and drain tanks. This means that only one pump needs to be installed. It is self-priming up to nine meters tank depth and is resistant to dry running - features that are important for tanker filling.

Vogelsang rotary lobe pumps can convey a wide range of media from the food, waste, oil and gas, chemical and cosmetics industries. They can be adapted to the medium in question, whether it is chemically aggressive or viscous. For example, a variety of materials are available for the lobes: elastomeric coating, stainless steel or polyurethane. Even substances containing foreign matter such as stones or hardened matter can be pumped without problems, since the patented injection system makes the pumps resistant to such matter.

The injection system helps the fluid go directly to the pump chamber so protecting the pump lobes. “That system favors the pump’s energy consumption because that means more sealing lines and accordingly reduced volumetric losses,” Mr Vogelsang added.

Depending on the required delivery rate and pressure range, with the VX series of the rotary lobe pump, clients can choose from five ranges each with eight different sizes. There are a range of drive and material variants available resulting in an all-round pump for a variety of applications including olive oil, molasses, food waste, organic fertilizer, liquid manure, fuel or oil, pumping the liquids at a delivery rate of 3 to 1,400 m³/h.

The rotary lobe pumps from the IQ series are ideally suited for use in tankers. They are compact, offer flexible installation with their variable connections and are easy to maintain. The pump housing consists of one complete part, meaning the inside of the pump can be accessed quickly. The gearbox housing’s new design with integrated liquid buffer ensures excellent dry running protection and a high suction capacity. The IQ pump operates at a delivery rate of up to 77 m³/h at a pressure of up to a maximum of eight bar.

“We have developed a special pump design to reduce energy consumption. Reducing the volumetric losses and accordingly increasing the efficiency of the system, is the main objective.” Mr Vogelsang explained.

The quick service VX and IQ series pumps are equipped with generous sized shafts that reduce shaft deflection to a minimum. That means low operating costs and low demanded energy. For a typical 200 m³/h capacity pump Vogelsang claims that a reduction in the demanded energy up to 17,000 kWh per year (around 11%) can be achieved.

The shaft deflection is caused by the differential pressure between the suction and the pressure side of the pump and that causes wear. The gap between the lobes increases and the backflow causes an efficiency reduction increasing the operating costs.

HiFlo lobes are another design feature that reduce energy consumption. They ensure efficient and pulsation-free pumping and, according to Vogelsang, provide a minimum of 50% extra sealing lines, with the consequence of having reduced volumetric losses and increased energy efficiency.

Founded in 1929 by Hugo Vogelsang, the Vogelsang group has developed from being a manufacturer of farm equipment into a specialist for innovative products deployed in biogas and wastewater technology, as well as vacuum disposal technology.

Vogelsang’s customers include biogas installation operators, agricultural companies, municipalities, shipyards, numerous industrial companies and rail firm Deutsche Bahn.

Vogelsang has been growing continuously, particularly since the 1990s. The workforce has increased from 100 to 650 employees worldwide, with new production buildings being constructed at the company’s headquarters and the machine outfit extended. Today, in Essen, more than 500 workers manufacture Vogelsang products in a production hall area covering over 14,700 m2, equipped with state-of-the-art automatically controlled production machines.

Future trends

Netzsch identified the health care and environmental care sectors as being important and that growth in the future will be driven by increasing safety and protection measures, worldwide certification and monitoring and the effectiveness of training, both in house and at customer sites.

“We consider that the main driver for chemicals pumping in the next decade will be related to service and maintenance. The cost of the spare parts and the energy consumption will be other decisive aspects to have in mind for the next few years.” said Mr Vogelsang. “Cost-benefit and efficiency will always be important,” added Mr Nornes. “If my concept will add to the cost-benefit ratio, it is important end users look past conservative patterns and give new ideas a chance,” he added.