Novel Approaches to Cooling Crystallization with Porous Bed Flow Type Crystallizer

Abstract

The invention describes a new way to cool the crystallization process that uses a porous tubular-type crystallizer that is built into metal wool. The crystallizer features a porous bed to enhance nucleation and control crystal size distribution, while in-situ direct cooling with liquid nitrogen allows for precise temperature control. This novel crystallization process is energy-efficient, scalable, and suitable for industries requiring high-purity crystal production, such as pharmaceuticals and fine chemicals.

Specification

Description:FIELD OF THE INVENTION:
The present invention pertains to crystallization processes, specifically focusing on a unique method of cooling crystallization through the use of a porous bed crystallizer. The crystallizer is filled with a porous material, possibly metal wool, which allows for enhanced control over crystal size distribution, crystallization efficiency, and product purity. This invention is applicable to industries such as pharmaceuticals, fine chemicals, and food processing, where crystallization is a key separation and purification method.________________________________________
3. BACKGROUND OF THE INVENTION:
Crystallization is a vital process in many industries, often used for the separation, purification, and solidification of products. Traditional cooling crystallization techniques, which rely on batch or continuous crystallizers, suffer from certain limitations, such as uncontrolled nucleation and poor control over the crystal size distribution. Additionally, thermal management or efficient heat transfer during crystallization is a challenge, as it directly influences the rate at which crystals form and their quality. The present invention introduces a novel cooling crystallization process that incorporates porous materials, possibly metal wools of stainless steel, within a tubular-type crystallizer to establish a porous volume. Additionally, the innovation focuses on an in-situ cooling method to address challenges and enhance the efficiency of crystallization processes.________________________________________
4. OBJECTIVES OF THE INVENTION:
The primary objectives of this invention are
1. We aim to introduce a unique cooling crystallization method that utilizes a porous bed tubular type crystallizer.
2. We aim to improve the heat transfer and mixing efficiency in the crystallizer by incorporating a porous structure.
3. We aim to improve the management of crystal size distribution and guarantee the production of high-purity crystals.
4. We aim to decrease energy usage and boost process effectiveness by enhancing the regulation of temperature profiles and heat transmission.
5. The goal is to create a system that can easily expand for industrial use without sacrificing efficiency.
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5. SUMMARY OF THE INVENTION:
The present invention discloses a novel cooling crystallization technique that integrates a porous bed within a tubular flow crystallizer. The process will be beneficial for applications related to the separation of a liquid mixture or solute from solution via crystallization at ultra-low temperature. The porous bed provides a large surface area for nucleation and crystallization, enhancing control over the crystallization process. We can design the flow characteristics of the solution through the crystallizer to maintain a uniform temperature gradient for controlled cooling. This configuration allows for precise control over supersaturation levels and residence time distribution, leading to improved crystal size distribution and reduced impurity levels.
A traditional crystallization setup typically consists of a tank equipped with an outer jacket for temperature control, filtration, and drying units for product separation after crystallization. Some processes necessitate washing the crystals after crystallization with other liquids, which may require further separation. The traditional crystallizer's method of mixing and heat transfer is ineffective. The invention introduces a cooling jacket surrounding the porous bed crystallizer with adjustable heat transfer parameters to enable efficient temperature control. The invention also includes provisions for control of supersaturation, nucleation, and crystal growth rates by adjusting the coolant flow rates. This invention greatly enhances the crystallization process, lowers the amount of energy needed, and raises the quality of the product by adjusting the flow dynamics of the porous volume inside the crystallizer.
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6. DETAILED DESCRIPTION OF THE INVENTION:
The cooling crystallizer consists of a long tubular chamber with a porous bed structure, which facilitates the crystallization of solution as it passes through it. Inert materials like metal wool (stainless steel), sintered glass, or porous polymer, with pore sizes optimized for nucleation and crystal growth, form the porous bed.
For the metal wool type structure, the chosen metal can either be highly conductive, and it must not react with the feed solution. Porosity can be uniform throughout or may vary as per design requirements. You can adjust the porosity along the crystallizer's length by pressing the metal wools. The porous volume should allow the liquid feed solutions to crystallize. We can apply the metal wool or porous beds in the catalysts or nucleating agents to increase their surface area and crystal-forming sites. This ensures an even distribution of crystal sizes. Illustrated in FIG .1.
An outer layer of insulation should cover the crystallizer to maintain its internal temperature or prevent heat loss to the surroundings. The proposed cooling system does not feature an outer jacketed structure encircling the cylindrical chamber. Instead, we propose an in-situ cooling method that uses liquid nitrogen (coolant) to transfer heat directly to the feed solution. Feed solution and coolant (liquid nitrogen) from separate tanks enter the crystallizer directly. Liquid nitrogen is an inert, non-reactive, colourless, odourless, and non-flammable liquid. Only physically mix liquid nitrogen with the feed solution. Before use, we should ensure its reactivity with the feed solution and porous bed materials.
The flow rates of both liquid nitrogen and feed solution streams should be maintained in such a way that the temperature of the mixture (after entering the crystallizer) should be near the freezing point of the required component in the solution and required flow condition. The pore size determines the size of the crystals that form, which then settle in a porous volume. Generally, the crystal size will increase along the length of the crystallizer due to more contact time. Therefore, one can adjust the variable porosity size along the length, the flow rates of feed liquids, and the crystallizer length based on the crystal yield requirement and contact time. The design should capture the formed crystal inside the pores and ensure sufficient permeability to allow the mother liquor to pass through.
The mixture of mother liquor and liquid nitrogen that will come outside the crystallizer can be stored at room temperature in a closed vessel. You can separate the liquid nitrogen as vapor from the mother liquor at room temperature. We can separate the mother liquor and recycle it. We can liquify the nitrogen vapor again for recycling, or we can reuse the vapours.
The crystallizer's porous volume will capture the desired crystals. The next step involves melting the crystals (either automatically when the crystallizer temperature rises or by washing with nitrogen vapor or melted crystal solutions) and recovering them in a separate closed vessel at room temperature. If this stream contains liquid nitrogen, you can separate it by evaporating it at room temperature. The melted crystals (products) can be stored separately. The nitrogen vapor can be again liquified to recycle, or the vapours can be reused. The process flow diagram is illustrated in FIG .2. , Claims:Claim 1: I/We Claim a method of cooling crystallization comprising:
(a) An insulated tubular chamber with a porous volume;
(b) Introducing a coolant and feed solution together within the crystallizer;
(c) Introducing an economical approach for crystal product's purification or recovery.
Claim 2: I/We Claim the method of claim 1, wherein the porous bed comprises of highly conductive material, and must not react with the feed solution. Possibly metal wools of stainless steel.
Claim 3: I/We Claim the method of claim 1, wherein the pore size of the porous volume is selected to control the size and distribution of the crystals formed along the length of crystallizer.
Claim 4: I/We Claim the method of claim 1, wherein the coolant is liquid nitrogen and in-situ cooling method suggested to transfer heat directly to the feed solution.
Claim 5: I/We Claim the method of claim 1, wherein the flow rates of the feed solution and coolant are controlled to maintain a desired temperature gradient within the crystallizer. To control super saturation
Claim 6: I/We Claim the method of claim 1, the process decreases the energy usage for coolant and boost process effectiveness by enhancing the of temperature profiles and heat transmission.
Claim 7: I/We Claim the method of claim 1, the separation and purification steps of crystal and mother liquor, post crystallization, is easier and economical

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