The best way to save energy in paperboard production--condensate recovery

At a time when the economy is opening and the market competition is becoming more and more intense, in order to effectively reduce production costs and increase the competitive advantage of enterprises, the amazing benefits and importance that energy conservation can generate are enough to affect the profit and loss of business operations. So, how Proper planning of energy-saving projects at the factory has become a major task for the industry.

As we all know, the recovery and reuse of steam condensate (Condensate) is extremely effective in recycling, and it is one of the most effective ways to save energy today; in particular, the steam used in the paper packaging industry is hot. Extremely high, if not used properly, let it be dispersed to the atmosphere, the waste of these energy sources is obvious, and it cannot be ignored.

However, at present, there are many methods for recovering and using steam condensate in the industry. Now based on our company's more than 20 years of experience in this field, we will explain and compare the various condensate recovery methods currently available in the market. For advanced reference in various industries. Currently, there are four types of condensate recovery in the market:

Not recycled at all:

Let condensate discharge into the atmosphere

Use advantages:

The condensed water produced by the heat exchange process of the paper machine equipment can be quickly discharged without any resistance or back pressure, and the heat exchange process can achieve the optimal heat exchange efficiency.

insufficient:

â—† Severe energy waste, especially when the equipment's own hydrophobic system is incomplete and there is a steam leak, the energy waste situation will be even more serious;
â—† The secondary steam generated by the condensate discharge can easily cause pollution in the factory environment and affect the working environment and factory image in the factory.

Open recycling:

working principle:

Condensed water is led to the open hot water tank via the recycling supervisor, and the condensed water is sent to the boiler storage tank or other equipment that must be hot water through the pressure device.

Use advantages:

â—† Low input costs (almost no need to purchase any equipment or accessories) but still achieve a considerable degree of energy savings:
â—† Due to the open (atmospheric pressure) environment, the condensed water produced by the heat exchange process of the paper machine equipment can be rapidly discharged without any back pressure, which can effectively avoid the situation of water accumulation in the pipeline.

insufficient:

◆ Even if the water temperature is below 100°C, it is highly likely that the temperature below 100°C will cause the reservoir to rupture or damage the pressurized water pump and piping valve fittings, resulting in frequent maintenance work and high long-term maintenance costs:
◆Because of the atmospheric pressure, when the water temperature exceeds 100°C (boiling point), boiling evaporation occurs and becomes secondary vapor and evaporates into the atmosphere. This recovery method can only recover 80°C-100°C. The following part of the heat energy, (about 50% to 60% of the total amount of corrugated paper that can be recycled), is not effective;
â—† The energy waste caused by the steam leakage from the hydrophobic system of the equipment itself cannot be improved;
â—† The same causes the pollution of the factory's secondary steam to affect the factory's working environment and factory image.

Semi-open recycling:

working principle:

The condensed water is led to the pressurizing device (recovery device) via the recovery main pipe, and then the condensed water is sent to the deoxidizing tank through the pressurizing device (recovery device), and is mixed with cold (soft) water and hot water in the deoxidizing tank. In this method, soft water preheating is performed to achieve the purpose of heat energy utilization, and then it is supplied to the boiler through a boiler water supply system (supplement water pump).

Use advantages:

This recycling method is carried out in a closed pipe network system in the process of recovery and transportation of condensate water (from the recovery of the main pipe to the recycling equipment), and the heat transfer and utilization of the mixture of cold and hot water can be compared. "Open-style" recycling yields slightly higher benefits.

insufficient:

This type of recovery method is used in the recovery and transportation of condensate water (from the recovery of the main pipe to the recycling equipment), although it is in a closed state (better than the open recovery method), but the deoxidation tank itself is still open. Because of the container, it is still impossible to prevent serious waste of heat energy.

Closed recycling:

1 Traditional Closed Recycling

working principle:

The condensed water is led to the recovery equipment via the recycling supervisor, and the condensed water is sent directly to the boiler via the recycling equipment.

Use advantages:

This kind of recovery method is used in the process of input and output of condensate recovery (the condensate is recovered in the closed pipe network system and sent directly to the boiler), which can effectively prevent the leakage of heat energy and improve the recovery of condensate. The utilization rate is the ideal recovery method among the various recycling methods mentioned above.

insufficient:

◆Because this kind of recycling method is in the entire process of recovery and transportation of condensate water (from the recycling director to the recycling equipment, and then the condensate water is directly transferred to the boiler using the recycling equipment), it is in a closed state, so it is often easy. Because of the increase in back pressure in the pipe network system, it causes difficulties in recovery and water accumulation in the pipeline, which in turn causes deterioration of the equipment's heating efficiency and even causes the “water hammer” phenomenon, resulting in damage to the equipment or pipe fitting system components:

â—†In order to prevent the adverse effects caused by the increase in back pressure in the above-mentioned pipe network system, and also to increase the pressure difference between the recovery equipment and the reclaimed pipe network system, the condensed water can be squeezed and naturally returned back to the reclaiming equipment. In the water storage tank, it is necessary to properly discharge the pressure through the pressure regulating valve installed in the recovery equipment, and at the same time when the pressure is reduced, it is impossible to effectively eliminate the waste of heat energy;

â—† If condensate recovery is difficult, it can easily cause serious accumulation of water in pipes and heat exchangers, causing deterioration of heating efficiency and "water hammer" phenomenon, which directly affects and shortens the service life of the machine. This is also an early stage. One of the bottlenecks of recycling technology that cannot be broken.

2 New double-slot self-priming closed recovery system

working principle:

Through the specially designed pressure and circulation of the recycling equipment and the operation of the syphon, a relatively low-pressure and forced suction method is used to recover the condensed water in the recovery pipe network system into the storage tank of the recovery equipment, and then directly pump Into the boiler; this recycling system is focused on the recovery of condensate water with extremely low back pressure, without the need for pressure reduction, through the well-designed system operations of pressure, circulation, and siphonage. The condensate is sucked back by forced suction instead of the usual pressure reduction before the condensation can be returned to the storage tank by natural squeezing. This feature can completely solve the condensate recovery system. Many problems.

Use advantages:

â—† Really "full hermetic" recycling to achieve the best energy-saving effect;
â—†Can eliminate the waste of thermal energy and overcome problems that are difficult to solve in recovery systems such as pump cavitation, recovery difficulties, and pipeline water accumulation.

(Author/Kunshan Solar Energy Technology Industry Co., Ltd.)
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