Merpro has available for rental dual purpose sand hand units capable of undertaking desanding and sand cleaning operations. Flexible design enables the units to be utilised for either function due to the innovative solid/liquid cyclone arrangement on the vessel in each unit. The units are skid mounted and available for short term or long term rental.

DESIGN CONFIGURATION
Each package comprises a vessel which is a variation on a typical Tore®Trap desander and
Tore®Scrub sand cleaning unit. The vessels are designed with two separate top sections that
allow the vessel to be used as both a desander and sand cleaning unit.
The top sections contain ceramic cyclones which remove solids from the liquid and a bottom
accumulator section that stores the removed sand. The main top compartment contains 3
ceramic cyclones which are used during desanding operations. The second top compartment
contains a single cyclone that can be used in combination with the cyclones in the main top
section for desanding, and is also used in the sand cleaning cycle.
 

A Tore® device is fitted in the bottom of the accumulator section and is used to remove sand
from the vessel via the external disposal line or to re-circulate sand during the cleaning cycle.

PROCESS DESCRIPTION
Desanding
In desanding mode, the unit can receive well fluids directly from the wellhead, or can receive
Produced Water from separator vessels, for example to protect PWRI pumps from sand
erosion.
When receiving well fluids or Produced Water from upstream separators, fluids enter the
vessel and pass though the cyclone compartment(s). The de-sanded fluid exits from the top
of the vessel and returns to the installation’s existing separators or produced water facilities.
The removed sand particles drop to the bottom accumulator section of the vessel. The
operator has the option of continuing to desand while operating the Tore in the base of the
accumulator section to remove accumulated sand, providing there is suitable disposal option
for the removed sand. Alternatively desanding operations can be stopped when the
accumulator section fills and the high level alarm point is reached, illuminating a beacon.
The unit can then be switched to Sand Cleaning mode.
Flow to the two cyclone compartments can be configured to use both (4 cyclones) or either of
the two compartments (3 or 1 cyclones).
A twin globe valve arrangement on the fluid discharge line allows the flow/pressure drop
across the vessel to be regulated and so maintain package performance, flow rates and
differential pressure across the vessel, which can be observed on local indicators.
Sand Cleaning
A cleaning mode is used to remove oil from the accumulated sand prior to its removal from
the vessel and eventual disposal.
Desanding operations must be stopped and the flow though the vessel reconfigured to recirculate
the sand from the base of the vessel, though the jet pump, through the single cyclone
section and back into the accumulator. The sand is circulated around this circuit for a predetermined
time or until a sample indicates the sand has reached the required standard.
The Tore® in the vessel is used to fluidise the sand thereby allowing it to circulate to the jet
pump. The high gravitational forces and attrition set up in the jet pump and the cyclone act as
scrubbing devices on the sand particles, removing oil from the their surface. The removed oil
leaves the vessel as oily water via the fluid discharge line to a suitable low pressure
destination. The pressure in the vessel required to expel the fluidised sand is generated by the
jet pump.
Operating as a Tore®Scrub, the unit is designed to clean sand to the typical standard of <1%
w/w oil on sand.
The Tore® and jet pump require a feed water supply to operate. There is a common feed
water supply header with individual lines containing isolating valve, flow indicator and
regulating manual globe valve to each device. The Tore® feed rate flow rate should be set to
4 m³/h and the jet pump to 12 m³/h.

Sand Disposal
For sand disposal valve sequencing is changed, and the Tore® is used to remove the
accumulated sand and discharge it via the slurry dispoal line to an external storage or disposal
system. The length of the sand disposal period is manually timed and will depend on
operating conditions. For a full load the period will be up to 55 minutes to remove sand and
flush the discharge pipework.
WEIGHTS AND DIMENSIONS
The general arrangement of the unit is shown in Figure 2 below.