Рекуперация тепла промышленной очистки

Комплексный поставщик решений по рекуперации и очистке промышленных отходов.

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как работает воздухо-воздушный теплообменник в системе рекуперации тепла NMP

Воздухо-воздушный теплообменник в установке рекуперации тепла NMP передает тепловую энергию между горячим, насыщенным NMP потоком отработанного воздуха из промышленного процесса и более холодным входящим потоком свежего воздуха, повышая энергоэффективность в таких отраслях, как производство аккумуляторов.

Горячий отработанный воздух (например, 80–160 °C) и более холодный приточный воздух проходят по отдельным каналам или через теплопроводящую поверхность (например, пластины, трубки или вращающееся колесо) без смешивания. Тепло передается от горячего отработанного воздуха к более холодному приточному воздуху посредством явного теплообмена. К распространённым типам теплообменников относятся пластинчатые, роторные и трубчатые теплообменники.

В конструкциях, предназначенных для NMP, используются коррозионно-стойкие материалы, такие как нержавеющая сталь или армированный стекловолокном пластик, чтобы противостоять агрессивному воздействию NMP. Увеличенное расстояние между ребрами и системы безразборной очистки предотвращают загрязнение пылью и отложениями. Конденсат контролируется для предотвращения засоров и коррозии.

Горячий отработанный воздух передаёт тепло свежему воздуху, предварительно нагревая его (например, с 20°C до 60–80°C) и снижая энергозатраты на последующие процессы. Охлаждённый отработанный воздух (например, с 30–50°C) направляется в систему рекуперации NMP (например, конденсации или адсорбции) для улавливания и рециркуляции растворителя. Эффективность рекуперации тепла составляет от 60 до 95% в зависимости от конструкции.

Это снижает потребление энергии на 15–30%, уменьшает выбросы парниковых газов и улучшает извлечение NMP за счёт охлаждения отходящего воздуха для более лёгкого улавливания растворителя. Такие проблемы, как загрязнение, решаются за счёт увеличения зазоров, использования извлекаемых элементов и систем очистки, а надёжная герметизация предотвращает перекрёстное загрязнение.

На заводе по производству аккумуляторов пластинчатый теплообменник подогревает свежий воздух с 20°C до 90°C, используя отработанный воздух с температурой 120°C, что снижает энергопотребление печи примерно на 701 тонну (3 тонны). Охлаждённый отработанный воздух перерабатывается для получения 951 тонны (3 тонны) NMP.

как работает теплообменник воздух-воздух при сушке древесины

An air-to-air heat exchanger in wood drying transfers heat between two air streams without mixing them, optimizing energy efficiency and controlling drying conditions. Here's how it works:

  1. Purpose in Wood Drying: Wood drying (kiln drying) requires precise temperature and humidity control to remove moisture from wood without causing defects like cracking or warping. The heat exchanger recovers heat from exhaust air (leaving the kiln) and transfers it to incoming fresh air, reducing energy costs and maintaining consistent drying conditions.
  2. Components:
    • A heat exchanger unit, typically with a series of metal plates, tubes, or fins.
    • Two separate air pathways: one for hot, humid exhaust air from the kiln and one for cooler, fresh incoming air.
    • Fans or blowers to move air through the system.
  3. Working Mechanism:
    • Exhaust Air: Hot, moisture-laden air from the kiln (e.g., 50–80°C) passes through one side of the heat exchanger. This air carries heat energy from the drying process.
    • Передача тепла: The heat from the exhaust air is conducted through the exchanger’s thin metal walls to the cooler incoming fresh air (e.g., 20–30°C) on the other side. The metal ensures efficient heat transfer without mixing the two air streams.
    • Fresh Air Heating: The incoming air absorbs the heat, raising its temperature before it enters the kiln. This preheated air reduces the energy needed to heat the kiln to the desired drying temperature.
    • Moisture Separation: The exhaust air, now cooler, may condense some of its moisture, which can be drained away, helping to control humidity in the kiln.
  4. Types of Heat Exchangers:
    • Plate Heat Exchangers: Use flat plates to separate air streams, offering high efficiency.
    • Tube Heat Exchangers: Use tubes for air flow, durable for high-temperature applications.
    • Heat Pipe Exchangers: Use sealed pipes with a working fluid to transfer heat, effective for large kilns.
  5. Benefits in Wood Drying:
    • Энергоэффективность: Recovers 50–80% of heat from exhaust air, lowering fuel or electricity costs.
    • Consistent Drying: Preheated air maintains stable kiln temperatures, improving wood quality.
    • Environmental Impact: Reduces energy consumption and emissions.
  6. Challenges:
    • Обслуживание: Dust or resin from wood can accumulate on exchanger surfaces, requiring regular cleaning.
    • Initial Cost: Installation can be expensive, though offset by long-term energy savings.
    • Humidity Control: The system must balance heat recovery with proper moisture removal to avoid overly humid conditions.

In summary, an air-to-air heat exchanger in wood drying captures heat from exhaust air to preheat incoming air, improving energy efficiency and maintaining optimal drying conditions. It’s a critical component in modern kiln systems for sustainable, high-quality wood processing.

как работает теплообменник воздух-воздух в системе подачи свежего воздуха

Воздушный теплообменник в системе приточного воздуха переносит тепло между поступающим свежим воздухом и выходящим отработанным воздухом, не смешивая два потока. Вот как это работает:

  1. Структура: Теплообменник состоит из сердечника с тонкими чередующимися каналами или пластинами, часто изготовленными из металла или пластика, которые разделяют входящий и выходящий потоки воздуха. Эти каналы обеспечивают теплообмен, сохраняя при этом изоляцию потоков воздуха.
  2. Передача тепла:
    • Зимой теплый воздух в помещении (выходящий) передает свое тепло более холодному поступающему свежему воздуху, предварительно нагревая его.
    • Летом более прохладный воздух в помещении передает свою «прохладу» более теплому входящему воздуху, предварительно охлаждая его.
    • Этот процесс происходит за счет теплопроводности через стенки теплообменника под действием разницы температур.
  3. Типы:
    • Поперечный поток: Воздушные потоки направлены перпендикулярно, обеспечивая умеренную эффективность (50-70%).
    • Противоток: Воздушные потоки текут в противоположных направлениях, что максимизирует теплопередачу (эффективность до 90%).
    • Роторный (энтальпийное колесо): Вращающееся колесо поглощает и передает как тепло, так и влагу, идеально подходит для контроля влажности.
  4. Преимущества:
    • Снижает потери энергии за счет рекуперации 50–90% тепла из отработанного воздуха.
    • Поддерживает качество воздуха в помещении, подавая свежий воздух и минимизируя затраты на отопление/охлаждение.
  5. Эксплуатация в системе подачи свежего воздуха:
    • Вентилятор вытягивает отработанный воздух из здания через теплообменник, а другой вентилятор засасывает свежий наружный воздух.
    • Теплообменник обеспечивает температуру поступающего воздуха (ближе к температуре в помещении) перед распределением, что снижает нагрузку на системы отопления, вентиляции и кондиционирования воздуха.
  6. Контроль влажности (в некоторых моделях):
    • Энтальпийные теплообменники также переносят влагу, предотвращая возникновение чрезмерно сухих или слишком влажных условий в помещении.

Система обеспечивает эффективность вентиляции, экономию энергии и комфорт за счет рециркуляции тепла при сохранении качества воздуха.

how does air to air heat exchanger work

An air-to-air heat exchanger transfers heat between two separate air streams without mixing them. It typically consists of a series of thin plates or tubes made of a thermally conductive material, like aluminum, arranged to maximize surface area. One airstream (e.g., warm exhaust air from a building) flows on one side, and another (e.g., cold incoming fresh air) flows on the opposite side.

Heat from the warmer airstream passes through the conductive material to the cooler airstream, warming it up. This process recovers energy that would otherwise be lost, improving efficiency in heating or cooling systems. Some designs, like cross-flow or counter-flow exchangers, optimize heat transfer by directing air in specific patterns. Effectiveness depends on factors like airflow rates, temperature difference, and exchanger design, typically recovering 50-80% of the heat.

Moisture transfer can occur in some models (e.g., enthalpy exchangers), which use special membranes to move water vapor alongside heat, useful for humidity control. The system requires fans to move air, and maintenance involves cleaning to prevent blockages or contamination.

how does a heat exchanger work in a boiler

A heat exchanger in a boiler transfers heat from the combustion gases to the water circulating in the system. Here's how it works step by step:

  1. Combustion occurs: The boiler burns a fuel source (like natural gas, oil, or electricity), creating hot combustion gases.

  2. Heat transfer to the heat exchanger: These hot gases flow through a heat exchanger—typically a coiled or finned metal tube or series of plates made of steel, copper, or aluminum.

  3. Water circulation: Cold water from the central heating system is pumped through the heat exchanger.

  4. Heat absorption: As the hot gases pass over the surfaces of the heat exchanger, heat is conducted through the metal into the water inside.

  5. Hot water delivery: The now-heated water is circulated through radiators or to hot water taps, depending on the boiler type (combi or system boiler).

  6. Gas expulsion: The cooled combustion gases are vented out through a flue.

In condensing boilers, there's an extra stage:

  • After the initial heat transfer, the remaining heat in the exhaust gases is used to preheat incoming cold water, extracting even more energy and improving efficiency. This process often creates condensate (water), which is drained from the boiler.

industrial air to air heat exchanger | counterflow heat exchanger

industrial air to air heat exchanger | counterflow heat exchanger

An industrial air-to-air heat exchanger transfers heat between two air streams without mixing them, improving energy efficiency in HVAC systems, industrial processes, or ventilation. A counterflow heat exchanger is a specific type where the two air streams flow in opposite directions, maximizing heat transfer efficiency due to a consistent temperature gradient across the exchange surface.

Key Features of Industrial Air-to-Air Counterflow Heat Exchangers:

  • Efficiency: Counterflow designs achieve higher thermal efficiency (often 70-90%) compared to crossflow or parallel-flow exchangers because the temperature difference between the hot and cold streams remains relatively constant.
  • Construction: Typically made of materials like aluminum, stainless steel, or polymers for durability and corrosion resistance. Plate or tube configurations are common.
  • Приложения: Used in industrial drying, waste heat recovery, data centers, and building ventilation to preheat or precool air.
  • Преимущества: Reduces energy costs, lowers carbon footprint, and maintains air quality by preventing cross-contamination.
  • Challenges: Higher pressure drops due to the counterflow design may require more fan power. Maintenance is needed to prevent fouling or clogging.

Example:

In a factory, a counterflow heat exchanger might recover heat from hot exhaust air (e.g., 80°C) to preheat incoming fresh air (e.g., from 10°C to 60°C), saving significant heating energy.

industrial air to air heat exchanger | counterflow heat exchanger

industrial air to air heat exchanger | counterflow heat exchanger

Does a heat exchanger remove humidity?

A standard air-to-air heat exchanger primarily transfers heat between two airstreams and does not directly remove humidity. The airstreams remain separate, so moisture (humidity) in one airstream typically stays within that airstream. However, there are nuances depending on the type of heat exchanger:

  1. Sensible Heat Exchangers: These (e.g., most plate or heat pipe exchangers) only transfer heat, not moisture. Humidity levels in the incoming and outgoing air remain unchanged, though relative humidity may shift slightly due to temperature changes (warmer air can hold more moisture, so heating incoming air may lower its relative humidity).
  2. Enthalpy (Total Energy) Exchangers: Some advanced designs, like rotary wheel or certain membrane-based exchangers, can transfer both heat and moisture. These are called hygroscopic or enthalpy recovery ventilators (ERVs). The core material or wheel absorbs moisture from the humid airstream (e.g., warm, humid indoor air) and transfers it to the drier airstream (e.g., cold, dry outdoor air), effectively managing humidity levels to some extent.
  3. Condensation Effects: In certain conditions, if the heat exchanger cools humid air below its dew point, condensation may occur on the exchanger’s surfaces, removing some moisture from that airstream. This is incidental, not a primary function, and requires a drainage system.

So, a standard heat exchanger doesn’t remove humidity unless it’s an enthalpy-type ERV designed for moisture transfer or if condensation occurs. If humidity control is a goal, you’d need an ERV or a separate dehumidification system.

heat recovery wheel air handling unit

A heat recovery wheel in an air handling unit (AHU) is a device that improves energy efficiency by transferring heat and sometimes moisture between incoming fresh air and outgoing exhaust air. Here's a concise explanation:

How It Works

  • Структура: The heat recovery wheel, also called a rotary heat exchanger, thermal wheel, or enthalpy wheel, is a rotating cylindrical matrix typically made of aluminum or a polymer, often coated with a desiccant (e.g., silica gel) for moisture transfer. It has a honeycomb structure to maximize surface area.

  • Operation: Positioned between the supply and exhaust air streams in an AHU, the wheel rotates slowly (10-20 RPM). As it turns, it captures heat from the warmer air stream (e.g., exhaust air in winter) and transfers it to the cooler air stream (e.g., incoming fresh air). In summer, it can pre-cool incoming air.

  • Типы:

    • Sensible Heat Wheel: Transfers only heat, affecting air temperature without changing moisture content.

    • Enthalpy Wheel: Transfers both heat (sensible) and moisture (latent), using a desiccant to adsorb and release water vapor based on humidity differences. This is more effective for total energy recovery.

  • Efficiency: Sensible heat recovery can achieve up to 85% efficiency, while enthalpy wheels may add 10-15% more by recovering latent heat.

Преимущества

  • Energy Savings: Pre-conditions incoming air, reducing heating or cooling loads, especially in climates with large indoor-outdoor temperature differences.

  • Improved Air Quality: Supplies fresh air while recovering energy from exhaust air, maintaining indoor comfort.

  • Приложения: Common in commercial buildings, hospitals, schools, and gyms where high ventilation rates are needed.

Key Considerations

  • Обслуживание: Regular cleaning is critical to prevent dirt or clogs from reducing efficiency. Filters should be replaced, and the wheel inspected for buildup.

  • Leakage: Slight cross-contamination between air streams is possible (Exhaust Air Transit Ratio <1% in well-maintained systems). Overpressure on the supply side minimizes this risk.

  • Frost Prevention: In cold climates, wheel frosting can occur. Systems use variable speed control (via VFD), preheating, or stop/jogging to prevent this.

  • Bypass Dampers: Allow the wheel to be bypassed when heat recovery isn’t needed (e.g., during mild weather), saving fan energy and extending wheel life.

Example

In a hospital AHU, a heat recovery wheel might pre-heat incoming winter air (e.g., from 0°C to 15°C) using exhaust air (e.g., 24°C), reducing the heating system’s workload. In summer, it could pre-cool incoming air (e.g., from 35°C to 25°C) using cooler exhaust air.

Limitations

  • Space: Wheels are large, often the biggest AHU component, requiring careful installation planning.

  • Cross-Contamination: Not ideal for applications requiring complete air stream separation (e.g., labs), though modern designs minimize this.

  • Cost: Initial cost is high, but energy savings often justify it in high-ventilation settings.

how does a cross flow heat exchanger work

A crossflow heat exchanger works by allowing two fluids to flow at right angles (perpendicular) to each other, typically with one fluid flowing through tubes and the other flowing across the outside of the tubes. The key principle is that heat is transferred from one fluid to the other through the walls of the tubes. Here's a step-by-step breakdown of how it works:

Components:

  1. Tube Side: One of the fluids flows through the tubes.

  2. Shell Side: The other fluid flows over the tubes, across the tube bundle, in a direction perpendicular to the flow of the fluid inside the tubes.

Working Process:

  1. Fluid Inlet: Both fluids (hot and cold) enter the heat exchanger at different inlets. One fluid (let's say the hot fluid) enters through the tubes, and the other fluid (cold fluid) enters the space outside the tubes.

  2. Fluid Flow:

    • The fluid flowing inside the tubes moves in a straight or slightly twisted path.

    • The fluid flowing outside the tubes crosses over them in a perpendicular direction. The path of this fluid can be either crossflow (directly across the tubes) or have a more complex configuration, like a combination of crossflow and counterflow.

  3. Передача тепла:

    • Heat from the hot fluid is transferred to the tube walls and then to the cold fluid flowing across the tubes.

    • The efficiency of heat transfer depends on the temperature difference between the two fluids. The larger the temperature difference, the more efficient the heat transfer.

  4. Outlet: After heat transfer, the now cooler hot fluid exits through one outlet, and the now warmer cold fluid exits through another outlet. The heat exchange process results in a temperature change in both fluids as they flow through the heat exchanger.

Design Variations:

  • Single-pass crossflow: One fluid flows in a single direction across the tubes, and the other fluid moves through the tubes.

  • Multi-pass crossflow: The fluid inside the tubes can flow in multiple passes to increase the contact time with the fluid outside, improving heat transfer.

Efficiency Considerations:

  • Crossflow heat exchangers are generally less efficient than counterflow heat exchangers because the temperature gradient between the two fluids decreases along the length of the heat exchanger. In counterflow, the fluids maintain a more consistent temperature difference, which makes it more effective for heat transfer.

  • However, crossflow heat exchangers are easier to design and are often used in situations where space is limited or where fluids need to be separated (like in air-to-air heat exchangers).

Applications:

  • Air-cooled heat exchangers (like in HVAC systems or car radiators).

  • Cooling of electronic equipment.

  • Heat exchangers for ventilation systems.

So, while not as thermally efficient as counterflow heat exchangers, crossflow designs are versatile and commonly used when simplicity or space-saving is important.

What is the difference between the crossflow and counter flow heat exchangers?

The main difference between crossflow and counterflow heat exchangers lies in the direction in which the two fluids flow relative to each other.

  1. Counterflow Heat Exchanger:

    • In a counterflow heat exchanger, the two fluids flow in opposite directions. This arrangement maximizes the temperature gradient between the fluids, which improves heat transfer efficiency.

    • Benefit: The counterflow design is typically more efficient because the temperature difference between the fluids is maintained across the entire length of the heat exchanger. This makes it ideal for applications where maximizing heat transfer is crucial.

  2. Crossflow Heat Exchanger:

    • In a crossflow heat exchanger, the two fluids flow perpendicular (at an angle) to each other. One fluid typically flows in a single direction, while the other flows in a direction that crosses the first fluid’s path.

    • Benefit: While the crossflow arrangement is not as thermally efficient as counterflow, it can be useful when space or design constraints exist. It is often used in situations where the fluids must flow in fixed paths, such as in air-cooled heat exchangers or situations with phase changes (e.g., condensation or evaporation).

Key Differences:

  • Flow Direction: Counterflow = opposite directions; Crossflow = perpendicular directions.

  • Efficiency: Counterflow tends to have higher heat transfer efficiency due to the more consistent temperature gradient between fluids.

  • Приложения: Crossflow is often used where counterflow isn't feasible due to design limitations or space constraints.

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