Ceramic Membrane Filtration for Silica Removal in Heavy Oil Recovery
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Solution Overview
Problem
Conventional oil recovery processes are inefficient for heavy oil, and existing methods for treating produced water to prevent silica scaling in steam generation equipment are costly and environmentally hazardous, as they require large chemical quantities and generate hazardous waste.
Innovation Solution
The use of ceramic membranes to remove silica and residual oil from produced water, combined with additional purification processes like reverse osmosis and evaporation, to produce high-quality boiler feedwater that prevents silica scaling and fouling in steam generation equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If chemical treatment (Warm Lime Softening followed by Ion Exchange) is used to precipitate silica, then silica concentration is reduced to suitable levels for OTSG, but the fine silica crystals are difficult to remove economically by conventional mechanical separation devices
Solution Approach 1:
The patent employs porous media including deep bed filters with specific porosity characteristics to capture fine silica crystals. The porous structure provides large surface area and appropriate pore size distribution to trap precipitated silica that conventional filters cannot remove effectively.
Solution Approach 2:
The invention uses composite treatment systems combining chemical precipitation with physical filtration through multiple media layers. The composite approach integrates different removal mechanisms (chemical precipitation, adsorption, physical filtration) to achieve effective silica removal that neither method could accomplish alone.
2Quantity of substance
If magnesium hydroxide and/or calcium carbonate sludge is added to trap silica precipitates, then silica is trapped, but large quantities of chemicals are required and large quantities of waste sludge are produced
Solution Approach 1:
The patent optimizes chemical dosing parameters and pH conditions to minimize chemical consumption while maintaining effective silica trapping. By carefully controlling process parameters, the system reduces the quantity of magnesium hydroxide and calcium carbonate required, thereby reducing waste sludge production.
Solution Approach 2:
The invention implements sludge dewatering and disposal systems that maximize water recovery from waste sludge and minimize the volume of material requiring landfill disposal. The system recovers water back into the process and reduces waste volume through mechanical dewatering.
3Reliability
If pH is raised by adding caustic to maintain silica solubility in evaporator, then silica based scales are prevented from fouling evaporator heat transfer surfaces, but operating cost increases significantly and the concentrate stream becomes extremely hazardous with pH higher than 12
Solution Approach 1:
The patent performs preliminary silica removal through chemical precipitation and filtration before the water enters the evaporator. By removing silica upstream, the system eliminates the need for high pH maintenance in the evaporator, avoiding caustic addition costs and hazardous concentrate stream generation while still preventing scale fouling.
4Object-affected harmful factors
If neutralization of concentrate stream is attempted to reduce pH, then pH is reduced, but silica solids precipitate which are very difficult to separate from the aqueous solution and hazardous gases such as hydrogen sulfide are released
Solution Approach 1:
The patent performs preliminary silica removal before concentration, so that when the concentrate stream is eventually neutralized, there is minimal silica present to precipitate and cause separation difficulties. This upstream removal prevents the formation of difficult-to-separate silica solids during neutralization.
Solution Approach 2:
The invention extracts and removes silica and other problematic constituents from the water stream before concentration and neutralization steps. By taking out the silica early in the process, the subsequent neutralization step does not generate difficult-to-separate solids or release hazardous gases from silica reactions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces silica concentrations, prevents equipment fouling, and minimizes chemical usage and waste production, leading to a more economical and environmentally friendly steam generation process for heavy oil recovery.
Implementation Method 1
The produced water having the precipitated silica is directed to a membrane, such as a ceramic membrane, which removes the precipitated silica from the produced water
Implementation Method 2
Another embodiment of the invention includes a reverse osmosis unit interposed between the membrane and an evaporator. The reverse osmosis unit produces a high quality permeate from the membrane permeate
Implementation Method 3
The evaporator produces distillate that forms boiler feedwater
Implementation Method 4
converting the feedwater into steam having a quality of approximately 70% to 100% for injecting into the oil bearing formation
Data Source
AI summary
An oil recovery process utilizes one or more membranes to remove silica and/or oil from produced water. In one method, the process includes separating oil from produced water and precipitating silica. The produced water having the precipitated silica is directed to a membrane, such as a ceramic membrane, which removes the precipitated silica from the produced water. In some cases, residual oil is present and is also removed by the membrane.