PTQ Q2 2023 Issue

For the testing of fouling in distillation towers (trays and grid provided by a third-party vendor), a 12in ID pipe with cartridge-style trays and/or grid is installed in place of a storage vessel. Figure 1 shows two trays installed along with three foulant collection points for the distillation inter - nal evaluations. Pilot testing for fouling in a distillation tower set-up is typically divided into three main stages: • Evaluate the effectiveness and impacts of different addi - tives on fouling reduction and mitigation. The main objec - tive of this stage is to determine the best additive • Determine the minimum required dosage of the best additive to mitigate fouling and improve performance dur - ing commercial operations • Determine the impact of different internal tower configu - rations and designs (installing grid/packing instead of trays) without additive injection. Once the crude (in this example, coker kerosene pump - around material) is added and fills the testing loop, flow circulation is initiated. Then, the temperature of the system is increased to a final target temperature of 600-610°F (315-321ºC) on the top tray. A system pressure of 47-60 psi is maintained by utilising a pressure control valve on the storage vessel. For the coker kerosene pumparound material, WRI per - formed eight separate tests with the same duration and operating conditions for the three stages of pilot testing, with fresh material charges for each test. The amount of fouling and severity was qualitatively characterised by opening the distillation tower between and after the opera - tion to visually inspect for fouling. Quantitatively, the mass of foulant material collected and the pressure differential across the distillation tower were used as tools to quantify the fouling severity. Three foulant collection locations were identified and are labelled on the distillation vessel in Figure 1. Furthermore, the results from testing heaters, piping, and distillation fouling configura - tions are discussed in the following sections. Immersion heater An electric immersion heater in a pool of topped Athabasca bitumen was tested in a once-through configuration at WRI. After 80 test runs, without the benefit of an additive, the maximum sustainable temperature was around 755°F (402ºC). When the temperature was above 755°F (402ºC), toluene insolubles in the outlet accelerated until the tem - perature hit a maximum before dropping due to foulant build-up on the immersion heater. The fouling mechanism was heavy hydrocarbon thermal coking. Figure 2 shows a test run where the immersion heater was pushed above 755°F (402ºC) to test the benefit of adding the nano-additive, a high-temperature disper - sant comprised of magnesium oxide (MgO) nanoparticles dispersed in magnesium sulphonate (MgSO3H). 300 ppm of the additive was injected into the feed once the heater had been fouled and the performance had deteriorated. The additive immediately improved the operation, effec - tively ‘cleaning’ the foulant off the immersion heater and allowing the immersion heater temperature to reach a new

Optional sample port

Heater EH-703

PSV 7030

Vent to are

Additive addition

To blowdown

N purge

Crude from bbl

PSV

Distillation vessel

Sweep gas

Pump P-207

Sample box

Strainer

Continuous pilot testing Suncor Energy, an integrated energy firm, owns and oper - ates bitumen upgrading and refining operations that include atmospheric and vacuum separation, coking, hydrocrack - ing, and hydrotreating units. Various additives have been investigated and tested to varied degrees of success. To improve the selection and utility of additives, a low-cost and agile pilot plant testing set-up was created at the WRI. The purpose of continuous pilot testing is to create conditions similar to field operations to replicate fouling conditions and determine the impact of additives on mitigating and sup - pressing the amount of fouling in various situations, such as an empty pipe, heat exchanger, reactor, and in trayed/ packed tower columns. Pilot testing methodology WRI developed a continuous closed flow loop pilot operat - ing at 5-10 b/d under representative process conditions up to 300 psig and 780°F (416ºC). In one set-up, shown in Figure 1 , the target crude material is introduced into the flow loop and passed through an electric heater. The flow, pressure, and temperature are set to the desired conditions, and the material is circulated. Pressure indicators are used to gauge any increase in foulant material. The pilot is oper - ated until a noticeable pressure drop is witnessed in the pipe segment. Depending on the material and conditions, the pilot can be operated until the pipe is fully plugged, if desired. For additive testing, a fresh batch of crude is injected and operated at the same conditions but with the additive in place. Different concentrations can be tested. The difference in time to become plugged or reach a certain level of foul - ing can be compared with the base case operation with no additive. A variation in testing is to inject the additive part- way through the foulant generation step to investigate if the additive (type and concentration) can both mitigate fouling and remove previously generated foulant (a mid-run option). Figure 1 Pilot testing rig with both piping investigation set-up (in red) and distillation step-up noted together

PTQ Q2 2023