The plant of УОК series of JSC Group of companies "CHEMAGREGAT" for cooling (hardening) oil decoking during olefins production.
The plant of УОК series are completely automatic and provide decoking up to 98% and no particles larger than 50 um in the hardening oil circulation (HOC) loop in the pyrogas plants. Coke is unloaded as dry mass cleaned from the hardening oil. The plant configuration, capacity of the removed coke, is defined during technical assignment approval by the customer and depends on the amount and kind of the processes raw material.
Description of the plant of УОК series
The plant of УОК series has 2 cleaning steps with continuous operation cycle. СУ and automatic devices provide complete automatic process control including cleaning, drying and unloading of the coke. The plant УОК may be equipped with the container supply system for coke unloading.
The 1st cleaning step — centrifugal separators for liquid flow and solid particles separation of LAKOS (USA) where 100% of the flow is supplied from the hardening oil circulation loop. The first step task is to provide separation of the coke particles, after that the main flow of clarified oil is supplied back to the circulation loop and coke-saturated one (less than 1% of the main flow) is supplied through the drain separator outlet to the 2nd cleaning step where final decoking is performed.
LAKOS separators are more energy efficient against the conventional hydrocyclones and provide maximum flow separation from solid particles in case of pressure drop from 0.06 MPa to 0.08 MPa. Conventional hydrocyclones for efficient operation require the pressure drop of 0.15 MPa and more.
LAKOS separators have significantly larger lifetime, more than 20 years, against hydrocyclones due to the fact they do not have cone sand drains exposed to intense erosion wear.
Implementation of LAKOS separators allows to provide the plant of УОК series with high indexes, up to 98%, of hardening oil separation from the coke solid particles.
Fig. 1 shows the main elements of the LAKOS separators construction protected by patents. Tangentially located slots of the internal separator chamber operate as flow accelerators and provide maximum level of centrifugal separation of the liquid flow and solid particles, up to 98%.
2nd cleaning step — filtering plant in explosion-proof version produced by the company DURCO FILTERS by ASCENSION, USA. Filters crack size is 500 microns. As the operating filter is filled with coke and reaches a certain pressure drop, СУ connects coke-free filter, stops the supply of hardening oil to the filter filled with coke and actuates washing and drying mode. After coke drying and pressure drop in the filter are complete, СУ outputs the signal of the filter readiness for dry coke unloading. For fast and efficient coke unloading, each filter is equipped with high frequency pneumatic vibrator and hydraulic drive system for the unloading gate opening/closing. After the coke is unloaded from the filter and the unloading gate is closed, the filter is ready for operation.
The figure below shows the filter of company DURCO FILTERS by ASCENSION with the hydraulic drive system of the unloading gate and high frequency vibrator.
Washing and drying of coke, unloading from the filter
After shutdown of the hardening oil supply to the filter from the first cleaning step and washing start, СУ supplies fuel gas in it which replaces the existing hardening oil supplied through the drain to HOC loop. Then pyrolysis petroleum washing the coke from the hardening oil residuals and other heavy carbons is supplied to the filter and to HOC loop through the drain. After petroleum washing, coke is purged with overheated water vapour which completely releases it from petroleum and other residual hydrocarbons. Then it is finally dried with nitrogen which is released to the atmosphere through the drain. After the complete pressure release in the filter, dry odourless coke is ready to be unloaded. A container is supplied to the unloaded gate, hydraulic drives initially open the gate lock, the filter gate itself. Pneumatic drive provides complete coke unloading from the filter. After that hydraulic drives close the gate and the gate lock in the reversed order. Washing, drying and unloading of coke takes approximately 2 - 2.5 hours.
The scheme of plant УОК–3000–01 with the volume of the cleaned hardening oil from 800 m3/h to 3200 m3/h and filtration up to 16 tonnes of dry coke per year.
Below. there is the scheme of coke washing and drying in the filter.