Short cycle press machine|Secondary recycling temperature control system

Why we need to use a secondary recycling temperature control system for melamine lamination hot press

Overview

As one of the organic heat-carrying media, high-temperature thermal oil has gradually been popularized and applied for its advantages of boiling point, high heat capacity, low pressure, low energy consumption, simple system, and convenient control. Heating the thermal oil with a boiler is currently the most common method. When the process requires a high-temperature error, it is not advisable to send the thermal oil from the boiler directly to the hot plate of the short cycle press machine. This mainly has the following problems:

1. Under normal circumstances, if the boiler is far away from the processing workshop, the pipe heat loss will be large, and the use temperature will be uneven;

2. The pressure loss along the line is large, coupled with the small resistance of the hot plate channel,

3. In order to increase the temperature of the thermal oil in a short period of time, the hot oil pump for the boiler generally uses a relatively large flow rate, so the head of the hot oil pump must be large;

4. Due to the long-distance, when the temperature of the hot platen has a deviation, the correction speed is slow (because when the temperature of the hot platen is lower or higher than the set requirement, the electrical signal is immediately fed back, and the boiler is heated or cooled immediately, but the thermal oil temperature cannot be changed), which affects the product quality;

5. The temperature of the boiler outlet itself has a large change. This is because the thermal oil is not heated to a set temperature like steam or water before being used. It is circulated during the heating process, and only the part that circulates into the boiler is used. Being heated, the greater the circulation distance, the greater the temperature change.

In order to solve these problems and meet the process design temperature requirements, we set up a circulation system next to the hot press. This system is called the thermal oil heating secondary recycling control system (or internal circulation system).

Working principle

The design of the heat-conducting oil secondary circulation system unit: use a temperature controller and an electric three-way valve to adjust the flow rate in the pipeline system, and realize two different circulation systems by changing the flow direction of the heat-conducting oil to reach the temperature required by the press.

1. When heating up: the heating regulating valve is opened to allow the high-temperature hot oil from the boiler to flow to the temperature control unit group.

The hot oil circulating pump of the system is used to pump to the required heating equipment, thus forming a heating cycle. The operation of this circulation system is that the boiler hot oil passes through the heating regulating valve, flows to the hot oil circulation pump, and then flows to the required heating equipment, and then returns to the boiler oil return pipe to form a heating circulation system.

2. Constant temperature operation: When the system temperature slowly approaches the set temperature, the heating valve is gradually closed, and the regulating valve at the end of the system is gradually opened to ensure that the pressure of the system is stable. The boiler comes directly from the regulating valve at the end of the pipe. Back to the boiler, at the same time, the heat transfer oil in the temperature control unit group flows to the equipment through the hot kerosene circulation pump and then returns to the inlet of the hot oil circulation pump to form a constant temperature circulation system.

Advantage

1. High heat transfer coefficient, good effect, compact equipment, small volume, and small installation space

2. Temperature control is more precise

3. Conducive to the quality of the finished product.