Continuous Proppant Coating Using Residual Heat for Energy Reduction
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Solution Overview
Problem
Current methods for coating proppants require heating to high temperatures, are energy-intensive, and involve complex batch processes, leading to increased costs and logistical challenges in hydraulic fracturing operations.
Innovation Solution
A continuous process that involves washing, drying, cooling, and then mixing coated proppants with a coating composition in a combined continuous mixer and conveyor unit, where the residual heat from drying is used for curing, eliminating the need for additional heating and simplifying the coating process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If particles are heated to high temperatures before coating, then the polymer coating cures properly and particles stick together, but energy consumption increases significantly
Solution Approach 1:
The particles are dried at high temperature (500-1500°C) before coating to remove moisture. This preliminary drying action prepares the particles for coating, and the residual heat from drying is utilized for the coating and curing process, eliminating the need for separate heating after coating application.
Solution Approach 2:
Instead of discarding the residual heat from the drying process, the invention recovers and utilizes this thermal energy for the subsequent coating and curing operations. The hot dried particles serve as the base for coating application, and their residual heat completes the curing process without additional energy input.
2Ease of manufacture
If batch mixers are used for coating particles, then coating can be applied, but the process becomes complex and requires multiple material handling stages
Solution Approach 1:
The invention combines the coating application and curing operations into a single continuous process step. The coating composition is applied to the hot particles from the dryer, and the residual heat immediately initiates curing, merging what would traditionally be separate coating and curing stages into one integrated operation.
Solution Approach 2:
The process transitions from batch to continuous operation. Particles flow continuously from the dryer directly into the coating application zone, eliminating the loading-unloading cycles of batch mixers. The coating and curing occur continuously as particles move through the system, improving throughput and simplifying operation.
3Quantity of substance
If particles are dried at high temperature to remove water, then coating can proceed, but additional heating equipment and capital cost are required
Solution Approach 1:
The drying process serves multiple functions: it removes moisture from particles, heats the particles to temperatures suitable for coating adhesion, and provides the thermal energy needed for curing the coating. This multi-functionality eliminates the need for separate heating equipment that would otherwise be required for the curing step.
4Reliability
If thermoplastic resins are used for coating, then particles stick together, but heating above 120°C is essential to melt the resin
Solution Approach 1:
The particles are pre-heated to high temperatures (500-1500°C) in the dryer before coating application. This preliminary heating ensures that when the thermoplastic resin is applied, it immediately melts and bonds the particles together, eliminating the need for subsequent high-temperature heating that would be required if particles were coated at lower temperatures.
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 process reduces energy consumption, capital costs, and logistical complexities, while ensuring effective bonding of proppants, thereby enhancing their conductivity and reducing proppant flowback, thus improving hydraulic fracturing efficiency.
Implementation Method 1
curing the coating composition by transfer of heat from the particles
Implementation Method 2
drying the particles at a first predetermined temperature
Data Source
AI summary
A continuous process for forming a coated proppant, said process comprising the steps of: (a) washing particles, (b) drying the particles at a first predetermined temperature, (c) cooling the particles, (d) feeding the cooled particles with a second predetermined temperature lower than the first predetermined temperature to an inlet of a combined continuous mixer and conveyor unit, (e) feeding a coating composition into the combined continuous mixer and conveyor unit, (f) mixing and simultaneously conveying the particles and the coating composition for a predetermined time, (g) curing the coating composition by transfer of heat from the particles, (h) discharging the coated particles from an outlet of the combined continuous mixer and conveyor unit, wherein said process does not comprise a step of heating the particles after the drying.