RSS

Automated Blending

You may call it blending, mixing, pre-mixing, compounding.

Reduce the cost and increase the yield of your operation with intelligent automation. RTES adapts to your new or existing operation and makes it more efficient. RTES integrates with the other management tools in your plant.

No more wasted batches due to operator error. No more idle time. No more downtime while looking for the reason for a fault. Make your system fully visible and available.

The technical staff prepares the formulas (or recipes) using the 'recipe editing' screen. (view). In the example shown, you may use up to eight ingredients per formula.

You chose each ingredient from a drop down list, you enter the proportion for each ingredient, you give a name and a description (optional) to the recipe and you save it. The 'save' button only works if the percentage exists for all of the ingredients used. The percentage of the last ingredient automatically adjusts so that the total is 100%.

This screen is also used to edit (modify) existing recipes. You may type in the name of a recipe and click the 'get' button or click 'search' to flip through all the recipes in alphabetical order. Once the recipe is on the screen, you may change the ingredients, percentages and save it back.

The ingredients are stored in the ingredient tanks (view). Using the screen, you tell the system which ingredient is in which tank. You may assign more than one tank to an ingredient, or you may indicate that a tank is not used by not assigning to it an ingredient. To choose an ingredient for a given tank, you select the ingredient from a drop down list. Each tank may have a level detector or scale and also a temperature reading (thermocouple, RTD, etc.). The level and temperatures are displayed and may be used in the logic. For instance, you may tell the system to preheat a tank to a certain temperature before it is used to deliver the ingredient, you may prevent a recipe from executing if there is not enough ingredient, you may prevent agitation when the quantity of ingredient in the tank goes below a certain value (to prevent splashing).

Using the scheduler screen (view), you may now decide which formulas are going to be prepared, in what quantity and in which order. You select a formula, and the screen displays its details (ingredients and proportions). You assign a batch number, a batch size and you select a receiving tank. You then click the 'add' button to place the batch in the queue. There could be several queues in the system, depending on the architecture. If the piping and measuring devices allow it, several batches may execute simultaneously. Which queue each batch goes to is project dependant and decided by various criteria : the formula, the receiving tank, operator's choice. Once a recipe (task) is in the queue, you may remove it, recall it to change details such as batch size, proportions, etc. or you may give it a higher priority by moving it up on the queue. Optionally, the operator must authorize a batch before it is executed by the system.

Access to the screens for the ingredient tanks, recipe editing and scheduling may be restricted with a password to prevent tempering.

That was the 'bookkeeping' part. Now we move on the automation.(view)

When the system detects that a task on a queue is ready for execution, it initiates the batch. First, the system checks that the receiving tank (view) is available - either automatically or manually marked as empty. Then it identifies the ingredients, calculates the quantities, locates the ingredient tanks and checks that there is sufficient quantity to produce the recipe. If any of these preliminary checks fails, the status of the task is updated to reflect the reason why it is not running and the system tries the next task in the queue. The first queue that satisfies the requirements is moved up to the top of the queue and marked as active. The system then starts physically preparing the batch.

The valves and pumps are operated in the appropriate sequence to bring the required amount of each ingredient into the receiving tank. Ultimately, the aim of the system is to produce a batch as accurately and as consistently as possible. The measuring/weighing of the ingredients is done using various devices depending on the type of products being mixed. These include, level transmitters, mass flow transmitters, scales, load cells. There are various techniques used to obtain accurate quantities. The techniques used depend on the type of material, topology of the system, trade-off between speed and accuracy. Several techniques may be in use within the same system, the choices being made 'on the fly' according to some pre-determined rules.

The most simple method to deliver an ingredient is to start the pumps and open the valves until a quantity close before inferior to the total is reached, then jog the pump - a little bit at a time, waiting for stability in between - until the final quantity is reached. A more systematic approach is the aim at delivering half of the desired quantity, check by how much the system went over and then deliver the second half after it has been adjusted to compensate for the error that occurred as well as the one that will occur. In some situations, it may be necessary to take into account the quantity that will remain in the piping after the pump is stopped and blow it out with compressed air afterwards.

We may also identify one ingredient as the 'major' because its quantity is substantially larger that than of all the others and flood the piping with it before delivering the rest of the ingredients, thus creating a net displacement that eliminates errors due to product in transit (this would be necessary with long distances and/or wide pipes). A delivery may involve the use of an intermediate weigh tank (view), thus allowing the accurate introduction of additives in small amounts into a large batch.

The system may also allow for certain ingredients to be added manually, in which case the system warns the operator and provides all the instructions, asking for a 'done' signal when the addition is completed.

The system may also deliver a critical ingredient first, measure the quantity obtained and automatically adjust the other quantities to maintain accurate proportions.

While the delivery of the ingredients is going on, various abnormal situations may be detected, diagnosed and annunciated. These include valves that fail to close or open, leaks, blockage, pump failure, overheating, under-temperature.

The operator may suspend a task at any time. The task may then be resumed or aborted.

An image of the system status is constantly kept in non volatile memory so that recovery may take place after a shutdown occurs due to power loss.

Once a task is completed, an entry is made to a log file and a report is printed. Information may be passed on to other systems such as inventory control. The status of the receiving tank is changed to 'ready'. The receiving tank status must be changed to 'empty' before that tank may be used again by the system.

An automated blending systems consists of one or more computers for user interface, one or more computers that run the intelligent control system and a local or distributed data acquisition and control system to interface with the valves, motors, heaters, transmitters, scales, etc. You may select the hardware to be consistent with your own standards and even re-use any mechanization equipment currently installed. Our computer software adapts to all commercially available I/O subsystems, PLC's and instrumentation. It easily networks with the other computer systems used for plant management to provide a paperless and well organized operation.