A continuous flow line brings many benefits over batch production – mainly in time, hygiene, environmental impact and cost of operation. With a much smaller footprint, it provides greatly increased capacity and improved efficiency while reducing waste.
The traditional batch process is well established and used across multiple industries. It has benefits and, for many applications, it is a good solution for the job. It can handle small quantity production and provides the flexibility required when frequent recipe changes are needed. Quality assurance and traceability can be straight forward with checks and traces on individual batches – meeting the strict requirements of some industries. It does, however, have drawbacks and many are looking to reap the benefits of change to a continuous flow production line.
Batch production requires a large installation space and is a time consuming and costly process. Any capacity changes demanding scale-up of production need significant investment and space for additional tanks. Wastage levels across materials, water and energy are higher than in continuous production bringing greater costs as well as environmental impact. Large mixing tanks can lead to production challenges with homogenization of the whole batch making control of variables such as temperature, pH and viscosity difficult. For the production of household cleaning and personal care liquids, high active surfactants may create unwanted gelling and the agitating in an open vessel required lead to undesirable product aeration.
A continuous flow line brings many benefits over batch production – mainly in time, hygiene, environmental impact and cost of operation. With a much smaller footprint, it provides greatly increased capacity and improved efficiency while reducing waste. Inline mixing removes many of the problems associated with homogenising a static tank of product and, as the system is closed during production, hygiene factors are easy to handle. The more compact continuous process also has much lower requirements for cooling and heating – offering an appealing reduction in operating costs and emissions.
With smaller product wetted surfaces and fewer components (tubes, inline mixers, pumps and valves), the amount of raw materials left in the system means that Clean-In-Place (CIP) and Sterilization-In-Place (SIP) procedures can be optimized. Greater efficiency in this part of the process saves production time, significant amounts of wash water and reduces the loss of raw materials. Cost savings are also realised with reduced requirements for expensive wastewater disposal.
The continuous flow line brings much greater efficiency to hot and cold processes. Heating up or cooling down a batch process in a quick way, means to provide a high peak on energy to the vessel and agitation to get the energy through the tank wall into the material. Compared to a continuous flow, the energy flow is on a much lower level but continuous like the material flow. This saves investments on periphery. A heat recovery system may bring further savings, utilising cold process water to cool down the warm flow output.
Continuous flow production is nothing new – it is well established and widely used in industries such as brewing and dairy. However, the more viscous substances involved in the manufacture of detergents and household cleaning liquids with up to 40 dosing lines present new challenges. The behaviour especially the rheology of the raw materials is more complicated and areas such as pump control are harder to achieve. The flexibility for recipe and flow rate changes as offered by a traditional batch tank also needs to be addressed.
SPX, with its Bran+Luebbe offerings has worked closely with different customers who are leaders in the laundry and homecare market. Within the delivered process systems, a lot of batch production was removed and changed to continuous flow production lines for a variety of liquid cleaning products, such as fabric softeners, gel detergents and dish-washing liquids. SPX has performed extensive trials to ensure the variety of recipes needed work efficiently in the continuous system. It has harmonized technology to meet customer requirements and satisfy factory standards for products such as Pentax inline mixers capable of excellent mixing solutions of highly active surfactants together with water and other additives.
The production of household and personal care liquids has to have flexibility – the question is not if there will be changes to the process but when. A continuous flow skid must have the capacity and capability to add or change raw materials as well as change flow rate and mixing performance to meet demands. To address these needs, the systems are designed with reserve capacities. Additional space is allowed within the skid frame for extra pumps to handle future increases in the number of raw materials. Dependent on its properties, a change in raw material may be simply accommodated from an existing dosing line. Additional injection ports are, however, added as part of the design to enable the quick addition of new raw materials into the process.
SPX works closely with its customers, meeting their demands, and proposing new solutions to tackle the obstacles of moving to continuous processes for the production of household cleaning products and detergents. The methods used, are equally applicable to personal care products such as shampoos and shower gels. Their high production volume, small footprint, reliability and consistent performance deliver a just-in-time production strategy that saves operating costs, material costs and is environmentally friendly due to the lower amount of waste water generated during cleaning procedures. These savings make an operation more competitive, profitable and environmentally friendly. In tough economic times and with increasing environmental pressures, the benefits associated with continuous processing are difficult to ignore.
