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Inline blending can help process plants cut costs and reduce quality give-away

01.01.2012  |  Crisafulli, K. ,  ARC Advisory Group, 

Keywords: [blending] [batcol process] [inline blend] [product giveaway] [optimization]

In a traditional batch-blending process, the final product composition is created by combining different intermediate products (held in storage tanks) in a blend tank. The objective is to create final products that meet customer specifications. However, in many process manufacturing applications, tankless, inline blending may provide a better solution, particularly in grassroots process plants or for expansion projects in existing plants.

Inline blending involves continuous mixing of two or more intermediate products using flowmeters and control valves, to obtain a final product of strictly defined proportions. In theory, inline blending could enable process plants to save money by reducing the blend time, the need for excessive storage capacities and mix tanks, maintenance manpower and costly quality giveaway. Although not as well-established as batch blending, inline blending has also been around for years.

Blending systems. There are two basic types of inline blending systems: controlled-rate and flow-responsive systems. In controlled-rate systems, the flowrate is set by a blend controller and either manually or automatically controlled. The flowrate of the feed streams is maintained as the desired ratio of the component in the end product. Flow-responsive systems utilize the main feed stream as a constant to which all other intermediate stocks are blended at the desired ratios.

  Fig. 1. Typical inline blending system.
  Source: Jiskoot Quality Systems.  

Product and process optimization.

Blending involves numerous issues. What finished products are presently in demand by the market? What intermediate stocks and additives are required to make those finished products, and are they available? And, of course, which product will net the biggest profit? This represents a challenging optimization problem; it requires close coordination between marketing and operations groups.

Inline blending can help simplify this problem to a certain degree. Rather than holding several intermediate products in storage tanks where they are blended one at a time in a mixing tank, analyzed, re-blended (as needed), touched up and reanalyzed prior to delivery to the customer, inline blending allows the product to be analyzed continuously as it is being blended (enabling corrections to be made online as needed) and loaded directly to a truck, rail or tanker ship for delivery to the customer.

To achieve this, an inline blending system is typically comprised of two or more feed streams, each fitted with a strainer, flowmeter and control valve. As the feed streams are combined, the turbulence created is generally not enough to mix the components properly, often requiring an inline mixer to be utilized in the process. Once the intermediate products have been blended, an inline analyzer with a set trim point (such as density or viscosity) ensures that the final product meets minimum quality specifications. The analyzer and blend controller monitor the flow, ratio and trim of each stream continuously. Some inline blending unit suppliers also provide sampling features that take samples at set intervals throughout the blending process.

By reducing the need for mixing tanks, inline final product blending eliminates a time-consuming step to the process and can help reduce capital costs for the tanks themselves and labor costs associated with maintaining the tanks. Inline blending can also help increase flexibility and enable products to be blended on demand, rather than being stored onsite in anticipation of delivery.

Reduced quality giveaway.

In addition to reducing the time of the blend process and eliminating the need for separate blend tanks, inline blending also greatly reduces the risk of quality giveaway. As the intermediate products are combined at predetermined ratios and flowrates, and continuously analyzed throughout the process, production of a final product that over-conforms to the specifications of the desired product is minimized.

Typically, when batch blending, operators are overly cautious with their blends to ensure that their final product meets the customers’ product specifications. This can result in costly quality giveaway. When performed properly, inline blending allows the plant to tighten its control on the blending process and to more closely match the required specifications.

To account and compensate for stratification, tank heel or other process disturbances that may cause stream starvation, a trim strategy can be applied to help further ensure the product quality. A trim strategy throughout the process reduces variance in product quality, enhances product homogeneity and helps produce products as close to the desired specifications as possible. A trim strategy is a crucial aspect of the process, since it can help eliminate the need for re-blending or “touching up” the product after the fact. HP

The author 
  Kevin Crisafulli has over 10 years’ experience in software and manufacturing industries. He joined ARC in 2006 and holds a BS degree in marketing from Nichols College. 

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hi. im looking in line blending system for oil refinery.

Kwetishe, Philip Reuben

What capacity of refinery that batch blending will be required for the intermediate products. Pls I need your response.

Pavol Fehér, PhD.

Yes, it is a good job.
I have been dealing with this topic for 35 years at Slovnaft refinery in Slovakia. The main problem is to create, update and maintain a flexible inline blending system susceptible to mix pre-blends with various component composition&properties and their blending to other motor fuel components as well as to meet legislative and customers´requirements.
My work is aimed at the development of the mathematical formulae with blend indexes for blending in planning&scheduling (PIMS) as well as on blending unit.
They are some problems with quality giveaway reduction in the case of a large number of pre-blends and a lack of storage tanks.
An fuel optimizing requires quite amount of time and money on research to find the right mathematical formulae and set of instruments for quality giveaway reduction in RON, RVP, CN, FP or CP.

Dr. Oleg V Anokhin

Yes, interesting, perfect work and perspective work (idea) Mr.Kevin Crisafull !

I am Oleg V Anokhin, Dr. of Chemistry of Materials from Ukraine. (+ my CV )

I want propose for You pioner solutions for perspective composition materials + TextileFood + Medicine + Sorption systems etc. (metal foundry casting) industries on a basis of Bast Crops. (attachment article)

would like to specify that my scientific team consists of scientists from various institutes and local scientific and research associations. The team succeeded to develop completely new technology on processing of raw bust crops on the basis of colloid-chemical inputs. Note that the list of bust crops amounts to about 100 (hundred) cultivated in Ukraine, and their number in the world is quite bigger and they have higher commercial perspective while giving rather more quite interesting combinations and unique options of medical preparations in an instant from amorphous phase.

With regard to possibilities of the development we suggest, the technologists are provided with an attractive possibility on production of new types of food, functional fibre and medical drug formulations.

That is, the one that implements this very colloid-chemical approach will gain global priority in the world High-Technology industry + new source of raw materials on the whole range of bust crops.

I would like to draw your attention to the fact that the key moment for our development is processing of raw materials in the immediate proximity to the place of harvesting in order not to lose the amorphous phase of stem. This is the stuff that has not been processed at all for the time being and the stems, after harvesting the seeds, have been just left drying out afield. In any case our processes must give a step-like effect but provided for creation of mobile facilities.

As to the hemp fields, (all kind of bust crops) unfortunately, but we do not grow hemp, we are only scientists in the field of advanced technologies.

But still I would suggest the following scenario for our possible relations in this regard–
E.g. to start business based on implementation of the above solutions:
1) Hemp yields about 4-5 tonnes of stem (it can amount up to 7 tonnes) per hectare of uncollected stem at the fields after seed harvesting for oil production.
2) The cycle of hemp growth of 5 tonnes per hectare amounts to 100 days.
3) If cultivation of the land plot starts with a land plot of 10 meters by 1,000 meters (km) = hectare and the total amount of such sections (having 10 meters) will amount to 100 (i.e. the whole land plot will be 1,000 by 1,000 meters) than each day 5 tonnes of cellulose raw materials can be collected starting from the first planted section after 100 days of ripening. Furthermore, there will be no wastes as cellulose goes “its own way” and the liquid phase will be the raw material for new medical preparations.
4) By the way, this result will be better instead of waiting for

Mohiuddin Sardar

Inline Blending is interesting as an option during feasibility and concept studies. But the operations and maintainence wise it is not so userfriendly and therefore would require quite amount of time and money on research to find the right set of instruments supported with the right back up system to convince those that are expected to use them. This needs a lot of research which means money and time. However if there are examples where it has been proven to be in use successfully, without hiccups. Please send us references for feedback on existing online blending systems.

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