Heat recovery system of a cogeneration plant. Free electricity from waste heat - ORC generators
TM MASH LLC produces heat recovery (cogeneration) systems from diesel generator sets (DGS, DPP), gas piston plants (GPU, GPA, GPGU) and gas turbine plants (GTE). Heat recovery system for gas or diesel generator stations - a complex of thermal and mechanical equipment and devices that allow recycling thermal energy a number of gas turbine units or diesel generator sets, combine coolant flows in a collection heat point and supply heat to the consumer.
Actual assessment of heat recovery efficiency: Calculation of payback of SUT
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The main element of a heat recovery system (HRS) is a thermal module (TM), also called a heat recovery unit or module (HRU). It is the thermal module that utilizes heat from each power plant, which is combined with heat from other thermal modules and distributed to the consumer through a collection heat point. This system and is a heat recovery system. Combining the SUT with the cooling system of the diesel generator set and gas turbine unit (cooling radiators, also known as dry cooling towers, pumps and other piping) provides a complete thermomechanical system of the facility.
Examples of simplified thermal diagrams:
TM allows you to significantly increase the total efficiency - efficiency (fuel utilization factor) of a thermal power unit, bringing its value to 85-90%. Thus, the main objective of the heat recovery system is to save costs on heat generation; accordingly, the introduction of ECS in to the fullest is an energy saving technology. An example of calculating the payback of a heat recovery system can be found on this page.
During operation of an internal combustion engine (ICE), thermal energy is utilized in the TM as follows:
- An antifreeze heat recovery unit (AHU) removes the heat from engine antifreeze - instead of cooling the antifreeze on a cooling radiator (dry cooling tower), the antifreeze transfers its thermal energy to heat the consumer's water. UTA is a shell-and-tube or plate-type heat exchanger operating according to the “water/antifreeze” or “antifreeze/antifreeze” circuit (depending on which network coolant is used by the customer).
- The flue (exhaust) gas heat reclaimer (FG) removes heat from the exhaust gases of the engine: the temperature of the flue gases at the engine outlet is about 450-550 °C, the temperature of the gases at the outlet of the UG is 120-180 °C. This decrease in temperature allows for significant heating of the consumer’s water. UTG is a shell-and-tube heat exchanger operating according to the “water/flue gases” or “antifreeze/flue gases” scheme.
The total amount of utilized thermal energy is comparable to the generated electricity - on average, 110%-130% kW of heat is generated per 100% kW of generated electricity.
In case the generator electrical energy is a turbine unit, the thermal module includes only a flue gas heat recovery unit. The thermal power of the UTG is determined by the turbine parameters, but usually ranges from 120% to 145% of the generated electrical energy.
Calculation of the required network coolant flow:
Execution options
Heat can be recovered either separately from the antifreeze or exhaust gas circuits, or from both circuits simultaneously. Thus, the following versions of thermal modules are obtained:
- The thermal module is in full factory readiness (TM). It consists of two recovery heat exchangers, a gas flow switch, a bypass pipeline, piping, a frame base, a set of instrumentation and automation, and an automatic control cabinet (SHAU TM).
- Thermal module for exhaust gas heat recovery (TMVG). It consists of an exhaust gas heat recovery unit (EGH), an electrically driven gas flow switch, a frame base, an exhaust gas bypass line and a set of instrumentation and control equipment.
- Thermal module for antifreeze heat recovery (TMVV). Includes an antifreeze heat exchanger (UTA), piping, three-way valves and SHAU TM (if necessary). In thermal modules that utilize heat through both circuits, TMVG and TMVV can be located either on a single frame or separately, for example, TMVV inside a container, and TMVG on the roof, or on different floors of the energy center building. When ordering TMVG or TMVV, the corresponding truncated control cabinets can be included in the delivery package.
Equipment
Traditionally, a fully factory-ready thermal module includes:
- Exhaust gas heat recovery unit (EGH)
- Heat recovery antifreeze (UTA)
- Piping for antifreeze and network water
- Bypass pipeline with butterfly valves
Additionally, the heat recovery unit may include:
- Antifreeze and heating water pumps
- Protective casing for installing TM on the street / container roof
- Recycling system low-grade heat
- Network heat exchanger
Design features and advantages of our TMs
- Heat exchange tubes made of stainless steel 12x18n10t increase the durability of the product
- The fire-tube design of waste heat boilers makes it easy to clean the tubes from contamination; the design of the fire-tube heat exchanger is more compact.
- The compensator on the UTG casing protects the heat exchanger from damage in the event of an emergency violation of operating conditions
- Possibility of manufacturing exhaust gas utilizers with a reduced level of aerodynamic resistance (up to 2 kPa)
- The shell-and-tube design of the UTA facilitates its repair and cleaning in conditions of low transport accessibility (there is no need to replace gaskets between the plates)
- At the stage of agreeing with the customer on the layout of our thermal modules, we agree on the installation, connection and overall parameters of the thermal modules, which ensures a convenient supply of network water, antifreeze and flue gases
- Thermal modules are manufactured for a working pressure of liquid media – 0.6 MPa.
- All assembled thermal modules, as well as individual units, undergo mandatory hydraulic tests at our production. Test pressure – 0.8 MPa
- We can produce modules for pressures up to 4 MPa
- Assistance in the design and selection of related systems and equipment
- Flexible approach to customer requirements and wishes
Heat recovery system "TM MASH". Examples:
TM MASH LLC has manufactured control systems for almost all diesel generator sets and gas turbine units that are represented in Russia. Below are examples of various options for constructing cogeneration modules:
- Heat recovery system for GPU Caterpillar G3618B
- Open design (located inside a heated room);
- All thermal power (both exhaust and coolant) is utilized;
- Object: greenhouse farming in the Leningrad region;
- Heat cogenerator for GPU Caterpillar G3412
- Casing (hood) design (located on the roof of the container);
- Full thermal module;
- Object: industrial production near Magnitogorsk;
- Flue gas heat recovery device Caterpillar D3516
- Open design for location in a power plant building;
- Heat removal from the exhaust;
- Object: municipal diesel thermal power plant in the village. Tura (Krasnoyarsk region);
- Thermal module for antifreeze heat recovery for diesel generator sets based on the Caterpillar C18 internal combustion engine
- Open design for location in the energy center building on the side of the diesel generator set;
- Coolant heat recovery;
- Object: municipal diesel thermal power plant on the island. Sakhalin;
- Feature: the antifreeze heat recovery unit is built on the basis of a plate heat exchanger;
- Cogeneration module for gas piston unit Cummins 315GFBA
- Open design (in a frame - for indoor location on the second floor);
- Heat removal only from exhaust flue gases;
- Object: sports and recreation complex St. Petersburg;
- Heat recovery unit GPU Cummins 315GFBA
- Open design for indoor location next to the GPU;
- Heat is recovered from both circuits (full TM);
- Object: industrial production in Miass;
- Heat recovery boiler GPU Cummins 1750N5C
- Only the waste heat boiler (WTG) was manufactured directly;
- The heat of flue gases is recovered;
- Object: boiler house in Sochi;
- Complete thermal modules for Cummins KTA 50G3 and KTA 38G5 diesel generator sets
- Open version for indoor location near the diesel generator set;
- Heat removal from two circuits (exhaust gas circuit and coolant circuit);
- Object: municipal thermal power plant in Yakutia (Olenek village);
- Features: Flue gas heat recovery unit of water-tube type (the standard waste heat recovery boiler produced by TM MASH has a fire-tube heat exchanger configuration), antifreeze heat recovery unit based on a plate heat exchanger;
- Flue gas heat recovery unit GPU GE Jenbacher JMS 416
- Open design for placement on supports above the existing container with GPU;
- Heat removal from the exhaust;
- Object: logistics terminal in the Chelyabinsk region;
- Feature: The thermal module was installed on a site with an existing block-container gas piston installation;
- Open design for location on the roof of the room above the main gas control room;
- Complete heat recovery;
- Object: hotel and shopping center in Moscow;
- Feature: The GPU runs on liquefied gas (LPG – liquefied propane-butane);
- Cogeneration of flue gas heat from Capstone C1000 microturbine unit
- Open design for indoor location next to the microturbine unit;
- Heat removal from the exhaust (except for exhaust gases on turbines and microturbines, heat removal cannot be carried out anywhere else);
- An object: shopping complex in Magnitogorsk;
- Feature: Water-tube type heat recovery boiler (standard heat recovery boiler produced by TM MASH has a fire-tube heat exchanger configuration);
- Heat recovery units for GPU KamAZ
- Open thermal module on a frame for installation in a building;
- Complete thermal modules;
- Object: boiler house in Saratov;
- Heat recovery unit for exhaust gases and antifreeze of gas piston units based on the Daewoo Doosan internal combustion engine
- Open design for placement in containers with gas piston units;
- Complete heat recovery;
- Object: truck wash in the village. Sinyavino (Lenoblast);
- Flue gas heat recovery unit DGU UDMZ 6DM-21EL-M (Ural Diesel Engine Plant)
- Open design for placement on a container;
- Heat removal from the exhaust;
- Object: municipal diesel power plant for the far north;
- Flue gas heat exchanger GPU Arrow (China)
- Open version for location next to the hood type GPU;
- Heat removal from the exhaust;
- Object: taxi depot in Kurgan;
Consumption ecology.Technology: Heat is often seen as a waste, which makes people wonder how great amount waste heat can be converted into a source of electricity.
Thanks to rapid industrialization, the world has seen the development of a range of technologies that generate waste heat. Until now, this heat is often considered as waste, which makes people wonder how this huge amount of waste heat can be converted into a source of electricity. Now, as physicists at Arizona State University find new ways to generate energy from heat, that dream is actually becoming a reality.
Arizona State University Research Group:
Physics Professor Charles Stafford is the director research group, and he and his team worked to convert waste into energy. The result of their work was published in the scientific journal ACS Nano.
Arizona College of Optical Sciences scientist and PhD candidate Justin Bergfield shares the view that "Thermoelectricity can convert heat directly into electrical energy in a device without moving parts. Our colleagues in the field say they are confident that the device, computer model that we have designed can be built with the characteristics we see in our simulations."
Advantages:
Elimination of Ozone Depleting Materials: Using waste heat as a form of electricity has several advantages. It must be taken into account that on the one hand, the theoretical model of a molecular thermoelectric device will help in improving the efficiency of cars, power plants, factories and solar panels, and on the other hand, that thermoelectric materials such as chlorofluorocarbons (CFCs), which deplete the ozone layer, are obsolete.
More efficient design:
Research team leader Charles Stafford hopes for a positive result. He expects their thermoelectric device design to be 100 times better than previous efforts. If the design that he and his team made actually works, then the dream of all those engineers who wanted to generate energy from waste, but did not have the required efficient and economical device for this, will come true.
No need for mechanisms:
The thermal conversion device invented by Bergfield and Stafford does not require any machinery or ozone-depleting chemicals, as was the case with refrigerators and steam turbines that were previously used to convert waste into electrical energy. Now this work is performed by a layer of rubber-like polymer that is sandwiched between two metals and acts as an electrode. Thermoelectric devices are autonomous, do not require motor processes, and are easy to manufacture and maintain.
Energy waste disposal:
Energy is mainly generated by cars and industry. Automotive and industrial waste could be used to generate electricity by coating exhaust pipes with a thin layer of the developed material. Physicists also decided to use the law quantum physics, which, however, is not used very often, but gives excellent results, When we're talking about about generating energy from waste.
Advantages compared to solar energy:
Molecular thermoelectric devices could help generate solar energy and reduce dependence on low-efficiency solar cells
How it works:
Working with the molecules and wondering how to use them for a thermoelectric device, Bergfield and Stafford found nothing special until one student discovered that these molecules had a special function. A large number of molecules were sandwiched between electrodes and exposed to a stimulating heat source. The flow of electrons along the molecules was divided into two parts: the first part of the flow collided with the benzene ring, and the second with the flow of electrons along each subsequent branch of the ring.
The circuit of the benzene ring was designed in such a way that the electron moves a greater distance around the circle, which causes two electrons to fall out of the ring, reaching each other in phase on the other side of the benzene ring. The waves cancel each other out at the junction, and the gap in the flow electric charge caused by the temperature difference creates a voltage between the electrodes.
Thermoelectric devices developed by Bergfield and Stafford can generate enough power to light a 100-watt light bulb or increase the efficiency of a car by 25%.
Page 1
Utilization of low-temperature thermal energy in condensers of steam plants and heat exchangers gas installations can in principle be considered as one of the possible areas of application of thermoelectricity.
Utilization of the thermal energy of exhaust gases from boiler houses, diesel and gas turbine plants, regeneration of the thermal energy of the latter, production of heated water in contact water heaters, evaporative cooling and hygroscopic desalination of water, heat and humidity air treatment and wet gas purification - this is not a complete area of application of contact devices. This is explained, firstly, by the simplicity of their design and insignificant metal consumption compared to recuperative surface heat exchangers, and the possibility of manufacturing from non-metallic materials; secondly, by increasing the efficiency of installations due to more complete use of thermal energy, the possibility of improving the parameters of the thermodynamic cycle, regulating the flow of the working fluid, internal cooling or heating of the installation; thirdly, - the possibility of creating new installations and their technical systems, providing reduction in fuel, water, materials consumption, increasing power and productivity, improving working conditions and reducing pollution environment. The possibilities of using heat and mass transfer processes in contact devices of energy and heat-using installations have not yet been fully disclosed. This is facilitated by the existing purely empirical approach to calculation, which does not allow identifying the internal connection physical phenomena V complex processes heat and mass transfer, reflect this relationship in calculated dependencies and use it in practical activities.
The installation is designed to utilize the thermal energy of waste (spent) steam from autoclaves in the existing production of sand-lime bricks. Autoclave treatment of raw bricks with saturated water steam is the final stage in the production of sand-lime bricks, consuming a significant amount of energy resources. In this regard, the issue of ensuring more complete use of the thermal energy of exhaust steam after autoclaves and recovery of the resulting condensate is an urgent task.
The most common schemes for recycling the thermal energy of exhaust gases from piston engines include equipment for the production of steam with a pressure of up to 15 kg/cm, or hot water with a temperature of up to 100 C, or the direct use of heat from exhaust gases in drying processes.
This made it possible to approximately double the utilization of thermal energy and bring it to 22 million Gcal in 1985. The reconstruction of heat exchange units at 12 existing primary oil refining installations and the modernization of process furnaces made it possible to save almost 1 million tons of fuel equivalent in the Eleventh Five-Year Plan. Due to the use of additional quantities of refinery gas as fuel, which is currently burned in flares, as well as the introduction of 450 advanced air heating devices, 0.5 million tons of standard fuel were saved. During the years of the Eleventh Five-Year Plan, the industry saved about 900 million kWh of electricity and 1 8 million tons of standard fuel.
These blocks (Fig. 3.49) are designed to utilize low-grade thermal energy from ventilation emissions due to convection in heat exchanger blocks using aqueous solutions of glycol and ethylene glycol of various concentrations as a coolant.
Along with the advantages, the method of burning oil sludge has a number of disadvantages, the main of which are the difficulty of utilizing thermal energy, the bulkiness of the equipment, and air pollution, which does not always allow us to conclude that the use of this method is inappropriate.
The described installation scheme for using waste steam heat and condensate recovery makes it possible to fully and highly efficiently utilize the thermal energy of waste steam and return the resulting condensate for reuse both in the technological process and in a closed water supply system to produce saturated steam at the boiler plant.
Maintaining the technological process at particularly complex installations various systems for separate and simultaneous combustion of liquid, solid and gaseous waste chemical production, technologically related to the utilization of thermal energy and operating on solid, liquid or gaseous fuel.
Conducting the technological process of combustion of waste gases, natural gas, industrial wastewater, still remains and solid waste in combustion furnaces of various designs with the simultaneous management of lower-skilled operators, as well as maintenance of complex installations of various systems for the combustion of liquid, gaseous or solid waste from chemical industries that are not technologically related to the utilization of thermal energy or chemical raw materials.
There is an erroneous point of view that the use of low-grade heat from this source is of little practicality. At the same time, the utilization of thermal energy of steam distillate fractions would significantly reduce the consumption of circulating (or direct-flow) water, as well as reduce the thermal power of furnaces. If only 50% of the heat removed in condensers and refrigerators is used to preheat raw materials, then oil with an initial temperature of 10 C can be heated to 82 C.
Heating of cold Tyumen oil, selected at the headworks in one of the regions of Tatarstan, and its subsequent transportation within 10 - 180 minutes. It follows that desalting of Tyumen oil under soft operating parameters can be carried out on its way to the refinery and in cases where the effect of self-heating of oil during transportation is eliminated, but there are reserves of thermal energy to be utilized.
This not only pollutes air environment, but the generated thermal energy is not used. A number of experts believe that it can only be justified if thermal energy recovery and waste gas purification are combined. This process occurs at waste incineration stations (factories) that have steam or hot water boilers with special fireboxes. The temperature in the firebox must be at least 1000 C so that all foul-smelling impurities burn out. However, before being released into the atmosphere, gases must be purified, for example using electrical filters.
From a practical point of view, it should be noted that if the final stage of software processing and disposal technology is known, then they should be classified based primarily on this technology. The final stage of neutralization of most non-recyclable urban software (excluding particularly toxic ones, as well as inert construction garbage etc.) is currently burning. This is confirmed by the experience of centralized software neutralization in countries such as Denmark, Finland, Germany, Sweden, etc. With this technology, it is important to group all waste so that it organically flows into one or another technological chain leading to ultimate goal- - thermal neutralization of waste with utilization of thermal energy and other healthy products. Based on this, it is necessary to distinguish between combustible and non-combustible waste, within which, in turn, there are also differences in properties, phase state, processing methods, etc. Separately, it is necessary to highlight waste that can mutually neutralize each other or serve, for example, as reagents for processing emerging Wastewater. Waste containing particularly useful components, such as non-ferrous metals, must be separated and processed separately so that the final product does not mix with less valuable sludges. It is necessary to determine the heat balance between combustible and non-combustible waste, the internal heat demand of the centralized disposal station, the need for additional fuel, or the volume and ways of utilizing excess heat. This should determine the nature of the questionnaires or forms for one-time waste accounting.
We present an exclusive patented heat recovery system. Heating system and hot water supply for free at any time of the year!
It is difficult to imagine the world of modern man without electricity, water supply systems, heating and air conditioning. The cost of energy resources is constantly growing, and the issue of their effective use. Thermal energy recovery technologies are increasingly used at facilities for various purposes: from industrial production to public premises. This is due to the shortage and high cost of primary energy resources. Refrigeration systems in buildings, such as supermarkets or large refrigeration centers, consume a large number of energy to produce cold. At the same time, they also generate a significant amount of heat. This thermal energy is generated by the process of condensation of refrigerant gas. In conventional refrigeration units, it is released to the surrounding air using condenser units and is not used at all.
The purpose of creating such a system was to ensure 100% return of heat for heating and hot water supply, released during condensation of refrigerant vapors, into the room without negative consequences for operating modes of refrigeration equipment.
Today on Russian market There are no analogues in price, performance, versatility and ease of use. In addition, CTS is several times cheaper than existing analogues.
It is important to note that the installation of the RTS is very simple and can be carried out by any contractor involved in the installation of refrigeration equipment. More than half of the installations of the control system took place at work sites and took no more than 5-10 days.
Arguments in favor of the system:
The system is affordable! Its cost relative to other solutions is two to three times lower, given that it is completely independent - its own circuits, its own heat exchangers, its own automation. For an average store with 7-11 units of refrigeration equipment, the estimated cost of a turnkey system is 400-700 thousand rubles, and the payback will be 1.5-2.5 years. Almost any store or other owner of refrigeration equipment can afford to install a RTS.
Efficiency. The system allows you to shoot maximum amount heat, limited only by the performance of the compressors. If the performance of the fan coil units is sufficient, 100% of the condensation heat will enter the room. Compared to other recovery systems, the efficiency has more than doubled.
The ability to work with any refrigerant (R22, R404a, R407c, R134a, etc.) is achieved by adjusting the pressure regulators and direct heat removal.
Versatility. The system can be easily implemented on almost any refrigeration machines operating on freon: low-temperature, medium-temperature, air conditioners, chillers, etc. There are no performance restrictions. Together with heating, you can heat any medium, for example DHW.
The heat recovery system (HRS) is ideal solution For trading platforms with external cold. Most of After the implementation of UTS, customers refuse central heating.
Cold start. Proper design of the system, adjustment of automation and regulators make it possible to eliminate the presence of freon in the condenser and other heat exchangers on the discharge line.
Ease of use and regulation. The operation of the heating system does not depend on the number of operating or idle fan coils; each fan coil can be adjusted to its own temperature regime.
The recycling system for stores with remote refrigeration is constructed as follows:
A recycling module is installed in the compressor room (engine room of the store), next to the refrigeration machine. Its function is to distribute the flow of hot gas between indoor fan coil units and a remote condenser. Support required pressure in refrigeration circuits. In simple words, if the performance of the fan coil units is sufficient, then 100% of the hot gas will pass through their heat exchange part, if the performance is not sufficient (for example: several fan coil units are turned off or there is already heat) part of the heat from the hot gas will be utilized outside bypassing the heating circuit, but only as much as necessary.
In the heated room, special-design cabinet fan coil units are installed:
The function of fan coils is to transfer heat from hot gas into the room. Installed instead of or together with central heating radiators. The fan coil heat exchanger is made in accordance with all refrigeration laws. Specially designed for hot gas. Pressure testing of the heat exchanger 35 bar (3.5 MPa). Versatility. Can be mounted on a wall, ceiling, and even placed on commercial equipment (for example, on a refrigerated cabinet). The fan coil unit has a control panel with which the required temperature is set, upon reaching which it will turn off:
In our experience, when the recycling system is started, the temperature in the room rises by 10-15 degrees Celsius. The lion's share of properties refuse central heating. An electric curtain at the entrance + a recycling system gives +22 degrees Celsius in a well-insulated room all year round. Of course, a lot depends on the ratio of the performance of the refrigeration equipment to the area of the room, but in any case, the recovery system will return 100% of the condensation heat to the room. Using the example of the store in question, before installing the recycling system, the temperature in the room was +9 degrees Celsius, 6 hours after launch it was +24 degrees Celsius. Central heating didn't connect.
The payback period, depending on the complexity and configuration, is from 0.5 to 2 years.
TAS Retail provides comprehensive design, supply and installation of heat recovery systems.
Winters in Russia are harsh, and therefore another one was added to the list of “people’s signs” in the era of industrialization: if the drainage “floats”, the flange leaks, it means that the technological systems are working and are not frozen. If not, then, as they say, “it’s a big deal” - you’ll have to warm up the system and deal with icing. In the current century, much more effective approaches to ensuring the performance of thermal power and technological systems are available, but the habit of being lenient about steaming drains and leaking flanges remains.
Meanwhile, in this “thermal energy fog” money disappears without a trace - the money that was spent on heat generation. At a time when fuel and water tariffs are steadily rising, such neglect of energy resources is a missed opportunity in the struggle for efficient production.
In addition to steam, secondary resources also include other media technological processes, such as steam condensate after process equipment and cooling water. In 8 cases out of 10, in my practice (NPT), it is not used in any way at enterprises, but only requires additional disposal costs.
About how to transform low-grade heat into additional source savings - this article.
Low-grade heat: where to look and how to use it
In industry, low-potential energy resources are usually classified as secondary energy resources, which are liquids with a temperature of less than 100°C and gases with a temperature below 300°C. In practice, the upper temperature limit for a particular consumer can be taken as the temperature of the source, which allows its heat to be used for useful purposes using simple, long-known and relatively cheap devices - heat exchangers. The lower temperature limit of NHP sources may seem surprising, but modern compression heat pumps can extract heat from atmospheric air V winter time down to temperatures of -30°C. Not “warm” at all, but can be used for heating residential buildings and even industrial purposes (for example, heating remote industrial sites that have a reliable power supply and heating problems). The temperature ranges for using low-grade heat are presented in Figure 1.
Figure 1. An example of organizing a stepwise pressure reduction scheme and using a couple of different parameters.
On industrial enterprise sources of NPT are “ordinary”, characteristic of almost any production (heat of industrial wastewater, waste steam of technological units, heat of steam condensate after technological equipment or entering the condensers of heat engines with a turbo drive, heat that is transferred to the circulating water supply system as a result of cooling equipment and usually discharged into the atmosphere through cooling towers or directly into cooling ponds) and “specific”, characteristic of enterprises in a certain industry or region. Thus, petrochemical and gas processing enterprises, for example, are characterized by losses of waste flue gases from process furnaces; waste steam from distillation columns, vacuum systems, heaters; and heat of product flows.
How to use this heat? It all depends on the needs and tasks that you have in your enterprise. There are many options:
- used for heating, heating water to feed technological systems or its preliminary deaeration;
- return NPT to the technological cycle and reuse it in technological processes;
- use for heat supply to facilities remote from sources of cheap fuel;
- receive electricity in order to reduce the cost of purchasing it from a third-party supplier or to reserve power for your own needs.
Results:
- reduction of fuel costs and, accordingly, primary generation of heat or electricity;
- reducing the cost of purchasing water to feed technological cycles, processing it in water treatment systems and heating it to the temperatures required by technological requirements;
- reduction in costs for make-up water from recycled water supply (evaporates in cooling towers);
- reduction of CO 2 and nitrogen oxide emissions by reducing the amount of fuel burned.
Technical solutions
Currently, there are several fundamental technologies for .
Heat pump units (HPU)
Depending on the principle of operation, heat pumps are divided into compression and absorption. Compression heat pumps are always driven by mechanical energy (electricity), while absorption heat pumps use higher potential heat sources to extract NHP: hot water, steam, exhaust gases, direct combustion fuel.
Compression heat engines (CHEs) in the operating mode
steam pumps (HPU)
Figure 2. Operating principle of a compression pump
The principle of operation of the CTN is based on the ability of a low-temperature refrigerant to boil under conditions low pressure remove heat from a low-temperature heat source. The operating temperature range is selected by selecting a specific working fluid and operating pressure range. For special industrial installations, maximum temperatures of about 120÷140°C can be obtained using “cascade” connection schemes and appropriate refrigerants. Separate promising direction- high-temperature HPI using CO 2 with supercritical parameters.
Absorption heat engines in heat pump operating mode (ABHP)
The operating principle of ABTN is based on the ability of the absorbent solution to absorb water vapor having more low temperature than the solution.
The most widely used are absorption heat engines that use a solution of lithium bromide (LiBr) as an absorbent. The units provide water heating to temperatures of 60-90°C.
Such installations can be used in refrigeration machine (ABHM) mode, providing cooling of water (for example, process water) to temperatures of 5-15 ° C, regardless of the ambient temperature.
Figure 3. Operating principle of ABTM
Installations using the ORC cycle to generate electricity
home distinctive feature installations based on the organic Rankine cycle (ORC) - the use of an organic working substance instead of water vapor. This increases the overall efficiency of the thermal cycle at low powers and at low heat source temperatures compared to the classical steam cycle, since the boiling point organic matter less than that of water, and on the other hand, it limits their use at medium and high powers.
Interest in installations with ORC has increased significantly with the development of energy sources using non-traditional fuels (wood waste, biofuels), since when burning them it is difficult to ensure coolant parameters at the outlet of the installation that allow the efficient use of a conventional steam-water cycle.
Diagram 1. Area of effective application of installations with an ORC cycle
Currently, as part of improving the energy efficiency of enterprises in the petrochemical industry and others that use steam technologies of different parameters, modernization is being carried out with the replacement of reduction-cooling units (RCUs) with back-pressure turbines. In this case, steam with a pressure suitable for heat supply purposes is used as the lower limit of reduction. However, the consumption of thermal energy for heating is seasonal nature and limits the power generation capabilities of backpressure turbines, reducing economic efficiency. The use of ORC installations would allow us to avoid seasonal unevenness and serve as additional support for power supply for our own needs.
IN Lately The above technologies are increasingly used in various combinations with each other. For example, cogeneration is the connection of electricity generation installations, including those with an ORC cycle, and equipment to produce thermal energy of the parameters required by the consumer through the utilization of low-grade heat.
If a heat engine as part of an autonomous power supply installation is designed to operate both in heat pump mode and in “refrigerator” mode, the electricity generation system is converted into a trigeneration system to produce cheap electrical energy, thermal energy, and cold.
Condensate collection and return systems in manufacturing plants
The thermal energy contained in the steam condensate after its use in the technological chains of the enterprise should be returned as much as possible for subsequent use. At the same time, the condensate itself is an excellent source for feeding the steam process circuits of energy-producing installations, reducing the need for additional water preparation.
Main tasks in the design and operation of low-grade heat recovery systems
Linking existing sources of NPT and consumers, options for their use, taking into account the needs of a particular enterprise, while ensuring the economic efficiency of the project is a complex engineering task. To solve this problem, the development of a recycling system should include the following steps:
- conducting a pre-project survey of the energy system (data collection and compilation of energy balances, instrumental survey),
- modeling of technological processes of installations, the operation of which leads to maximum energy losses (mathematical modeling, pinch analysis),
- analysis of resource limitations when using NTP, development of options and selection of optimal solutions,
- analysis of economic limitations when using NPT in the conditions of a given enterprise and development of a feasibility study.
The specific design and operational features of NPT recycling systems are that almost all of them use low-boiling refrigerants in their work, i.e. actually “refrigeration” technologies. It is no coincidence that the safety issues of heat pumps are included in a single GOST with refrigeration machines (GOST EN 378-1-2014 Refrigeration and heat pump systems. Safety and environmental requirements. Parts 1-4). The experience of operating such technologies in Russia is significant.
The future of technology in Russia
The effectiveness of low-grade heat recovery technologies does not raise questions, so every year they are increasingly used throughout the world. The reasons for their slow implementation in Russia are economic. The low cost of energy resources and the relatively high cost of imported equipment lead to high payback periods for “standard” projects.
However, practice shows that the effective economics of a project is always a question individual approach and the responsible attitude of the contractor to the design of the system and the selection of optimal equipment and components. In addition, payback periods today are calculated based on current energy tariffs, while the upcoming liberalization of thermal energy tariffs will most likely lead to a sharp increase in the energy component of enterprise costs.
This situation will affect less than others those companies that are already beginning to optimize energy costs, in particular, thanks to reuse low-grade heat.
Igor Sokolov
Leading expert of the company "First Engineer"