Production line process technology plan
The construction of a production line with multiple functions, large scale, advanced technology and equipment, modernized electrical control, and overall advanced technology with contemporary international standards is the goal of the company ’s polyurethane waterproof coating production line design and the principle followed in the production line construction.
Design function and scale of production line
Polyurethane is a series of elastomers with more urethane groups (_N HCO) on the polymer main chain. It is divided into liquid coatings, paste-like sealing materials, bonding materials, anti-corrosion and wear-resistant materials according to different shapes and functions. A variety of products; according to the different packaging forms, it can be divided into two categories: two-component (multi-component) and single-component. The single component is cured by reacting one NCo_-end group of the polyurethane prepolymer with moisture in the air, and the two components are the A-B and B-ends of the A component after the A and B components are mixed in proportion. The group reacts with the catalyst in the B component to be cured into a film. According to an investigation of the domestic and foreign markets for polyurethane materials at that time, spray-type polyurea elastic waterproof coatings have quietly risen. Polyurethane waterproof coatings also have a variety of specifications, performance, and colors.
In order to make the completed production line work to the maximum and meet the market's needs for multiple varieties, high quality, and large quantities, we have determined the design goal of the production line: to produce both single- and two-component polyurethane waterproof coatings and two-component spray polyurea Functions of various products such as elastic waterproof coating, two-component building sealing paste and road and bridge sealing paste. The designed scale is 5000 tons per year (the capacity of supporting systems such as process pipelines is 10,000 tons per year, and the main equipment is reserved).
Production line system composition and process
Polyurethane materials from raw materials to the completion of each process is a chemical reaction process, according to its composition and process should be a fine chemical product, the requirements of the ratio, process control parameters, operating steps are extremely strict. To this end, we have conducted a full pre-investigation on the production line construction, conducted in-depth understanding and inspection of foreign polyurethane coating process equipment, and the production line determined on this basis consists of liquid storage, metering and transportation pipelines, reaction kettles, and vacuum pumping. System, nitrogen filling protection system, heating and cooling system, waste gas and cleaning liquid recovery processing system, PLC control system, automatic packaging system. In order to save construction investment, single- and two-component reactors are set separately, and supporting systems such as process piping systems are shared.
The production of polyurethane is a relatively complex physical and chemical process. It is very important to improve its mass and heat transfer processes, especially for organic reactions that have a relatively slow reaction rate and a certain degree of reverse reaction. How to ensure that the groups participating in the reaction It is the key to ensure the reaction speed and the degree of reaction to fully and uniformly mix in the reaction kettle, to increase the mass transfer interface of the reaction components as much as possible, and to ensure that the temperature in all levels of the reaction kettle is basically the same. Considering that each component of polyurethane has a certain viscosity, the reaction tank of Ф1600 cannot solve the problem well by relying on a single high-speed stirring type. In addition to the international advanced level, this reactor is equipped with a 750 r / min variable-frequency speed-regulating high-speed paddle-type agitator, and is also equipped with a 50 r / min anchor-type low-speed scraper-type agitator to ensure the effect of scraping. There is a uniform gap of only 5 mm between the anchor type stirring blade and the wall of the reaction kettle. The production of the reaction kettle and the stirrer is not difficult. Relying on close cooperation with professional manufacturers of chemical equipment, the equipment meets the design requirements well. Polyurethane production is also a repeated process of heating and cooling: polyether heating and dehydration, cooling reaction, exothermic heating of the reaction (requires timely removal of heat), cooling and discharging. In order to ensure product quality, the temperature control and duration of each stage have high and precise requirements according to the requirements of the process conditions. Such as steam heating and cooling water cooling, basically meet the requirements. However, our company does not have a steam boiler. If a steam boiler is added due to the needs of this production line, a large investment will be required in project investment, staffing and management. After repeated considerations, the dual-spiral heating and cooling methods were creatively adopted. One spiral heat-conducting oil was used for heating, and the other spiral cooling water was used for cooling to meet the requirements of process conditions. It better guarantees the temperature control requirements and temperature rise and fall speed in each stage of production. Compared with the jacketed reactor, the screw itself can play the role of reinforcing ribs, reducing the requirements on the reactor and improving the pressure capacity of the reactor.