"Dual Carbon" Is In Progress! HZSS Technology's Pfhe Is Highly Adapted To The Organic Rankine Cycle, Helping Waste Heat Recovery Power Generation To Be More High-Quality And Efficient

Many industrial production processes are energy-intensive, releasing a large amount of waste gas and steam, and there is a lot of waste heat. my country is rich in industrial waste heat resources, which account for about 17%-67% of its total fuel consumption, of which the recoverable rate is 60%. Especially in the steel, nonferrous metals, chemicals, cement, building materials, petroleum and petrochemicals, light industry, coal and other industries, waste heat resources account for about 17%-67% of their total fuel consumption, of which the recoverable waste heat resources account for about 60% of the total waste heat resources.

According to the temperature of waste heat resources, it can be divided into high-temperature waste heat (above 500℃), medium-temperature waste heat (200-500℃) and low-temperature waste heat (below 200℃). High- and medium-temperature waste heat can be used directly, but low-temperature waste heat has always been difficult to use. In the development of high-energy-consuming enterprises, by rationally utilizing low-temperature waste heat, energy can be greatly saved and enterprise operating costs can be reduced.

Low-temperature waste heat power generation is an efficient and energy-saving technology that turns waste into treasure. It generates electricity by recycling low-grade heat contained in medium- and low-temperature waste flue gas, steam, hot water, etc. emitted during the production process of industries such as steel, cement, and petrochemicals. This technology utilizes waste heat without directly consuming energy, does not cause any damage or pollution to the environment, and helps to reduce and minimize the pollution to the environment caused by direct discharge of waste heat gas into the air.

However, due to the low efficiency of the entire process and the inability of existing technologies to recover waste heat, modern industry loses a lot of energy, which goes directly into the air or cooling system. In order to effectively avoid such energy waste, the organic Rankine cycle low-temperature waste heat power generation technology came into being.

The Organic Rankine Cycle (ORC) reduces the temperature requirements and can efficiently recover medium and low temperature waste heat resources (below 350°C, low pressure or normal pressure), making it economically feasible to recover waste heat for power generation. It is of great significance to improving my country's energy utilization rate, energy conservation and emission reduction, and environmental protection.

ORC power generation principle and process

The organic Rankine cycle is a Rankine cycle that uses low-boiling-point organic matter as the working fluid. It is mainly composed of four parts: a heat exchanger, a turbine, a condenser and a working fluid pump.

The organic working fluid absorbs heat from the waste heat flow in the heat exchanger to generate steam with a certain pressure and temperature. The steam enters the turbine to expand and do work, thereby driving the generator or dragging other power machinery. The steam discharged from the turbine releases heat to the cooling water in the condenser, condenses into liquid, and finally returns to the heat exchanger with the help of the working fluid pump, and the cycle continues.

The entire ORC power generation system consists of four parts: heat source loop (red pipeline), organic working fluid loop (green pipeline), cooling water loop (blue pipeline), and power grid (yellow part).

ORC power generation system composition

1. The heat source (waste heat resource) flows in the red pipe shown in the figure, enters the evaporator of the unit, transfers the heat to the working fluid in the unit, and the temperature of the heat source water decreases and leaves the evaporator and is sent to the subsequent process;

2. The working fluid circulates back and forth in the green pipe shown in the figure. The liquid working fluid enters the evaporator, absorbs the heat from the heat source, becomes saturated or superheated steam, enters the turbine, and converts the heat energy into mechanical energy, while driving the generator to output electricity. The superheated steam working fluid then enters the condenser, is cooled by cooling water to become liquid, and enters the working fluid pump. The working fluid pump drives the working fluid to flow repeatedly.

3. Cooling water flows in the blue pipe shown in the figure. Driven by the water pump, the cooling water enters the condenser of the unit to cool the working fluid. The cooling water temperature rises and leaves the condenser and is sent to the cooling tower to dissipate the heat to the atmosphere.

4. The generator generates electrical energy and is connected to the power grid for use.

ORC power generation technology application direction

Organic Rankine cycle power generation technology can be widely used in steel, cement, petrochemical, electric power, metallurgy, glass and other industries, mainly in the following forms.

1. Industrial waste heat: Recycling industrial waste heat can reduce industrial energy consumption and greenhouse gas emissions. Most industrial processes or flue gases emitted by power plants can be used, and the temperature is generally not higher than 400°C.

2. Geothermal: Geothermal power generation uses geothermal steam or hot water as a heat source. The geothermal fields that have been discovered in my country are all hot water-type heat storage. The geothermal water used is mostly near saturation, and the temperature generally does not exceed 200°C.

3. Solar energy: Solar energy has low energy density and low heat source temperature, so an organic Rankine cycle thermoelectric system based on heat collection technology is required. After passing through the heat collection device, the temperature can reach 300°C. For example, using a flat plate collector to collect solar hot water below 100°C as a driving heat source, and using ORC turbines to form a low-temperature solar thermal power generation system can be used as a distributed energy source.

4. Biomass energy: The main reason why biomass power generation uses organic Rankine cycle is that organic working fluid has higher turbine efficiency when the unit scale is small. In addition, organic Rankine cycle is also used in occasions such as cold energy recovery of liquefied natural gas (LNG).

HZSS Technology High Efficiency Compact Heat Exchanger

In order to improve the efficiency of the organic Rankine cycle system, it is necessary to optimize the design of the system, including the determination of cycle thermodynamic parameters, the selection of working fluids, and the design of heat exchangers.

The heat exchanger is in direct contact with the heat source and the cold source, and is one of the key devices of the entire organic Rankine cycle. Its heat exchange efficiency has an important impact on the efficiency of the organic Rankine cycle. The design of the heat exchanger needs to be carried out according to the type and characteristics of the waste heat, including evaporators, condensers, preheaters, etc., and it is also necessary to consider issues such as anti-corrosion, anti-wear, dust and scale removal, and resistance reduction.

Diffusion welded plate-fin heat exchanger (PFHE) is suitable for heat exchange between gas and liquid and gas and gas. Compared with brazed plate-fin heat exchanger, it has the advantages of no solder, strong corrosion resistance (chlorine, acid, alkali, ammonia, mercury, etc.), high and low temperature resistance (-200~900℃), high pressure resistance (4-15MPa), low leakage rate (1*10-9Pa·m3/s), wide range of material application (titanium, stainless steel, nickel white copper, etc.). At the same time, secondary welding has no effect on the diffusion welding core weld.

The PFHE developed and produced by Shenshi Energy Saving is suitable for the organic Rankine cycle system. It has the characteristics of small size, high power, and solder-free welding. It has safety, high performance and high reliability.

HZSS Technology PFHE is highly compact, with a volume and weight of only about 1/6 of that of a traditional shell and tube heat exchanger. The core is made of vacuum diffusion welding, with welding strength equivalent to that of the parent material, no risk of welding plugging, and further enhanced corrosion resistance. It can prevent working fluid mixing, has an ultra-low leakage rate, and has a high heat recovery efficiency, which is more suitable for the organic Rankine cycle system than traditional shell and tube heat exchangers. Shenshi Technology PFHE has been used in various ORC systems, including heavy truck ORC systems, nuclear power ORC systems, ship ORC systems, etc.