Rules for operating digester boilers

Tilting boilers

Electric cooking boilers for functional containers (FE)

Steam digester boilers

Non-tipping boilers. Design, principle of operation

Food boilers. Schematic diagram

General information. Classification of cooking equipment

8. Food boilers from Metos and Falcon

1. General information. Classification of cooking equipment

Cooking is the main method of heat processing of food products. It can be produced in liquid (water, broth, milk, etc.) or steamed. When cooking, the liquid medium is heated to boiling temperature and the product is kept in it until cooked. The duration of heating depends on the thermophysical properties of the product (heat capacity, density, thermal conductivity), its geometric dimensions and shape.

The product is considered cooked when the temperature in its center reaches 98-100 °C. The heat flow during the preparation of a product is directed from its surface to the center. The main type of heat transfer is thermal conductivity. The thermal conductivity of a product depends on its moisture content. The higher the moisture content in the product, the higher the thermal conductivity coefficient. When the moisture content of the product is 95-98%, its thermal conductivity is approximately equal to the thermal conductivity of water. At a temperature of 100 °C, the thermal conductivity of water is 0.68 W/(m K). The thermal conductivity of most food products ranges from 0.12 to 0.58 W/(m K). Low thermal conductivity (0.12) is typical for products with a moisture content of 10-12%, i.e. for dry products. The thermal conductivity of water is considered quite high compared to the thermal conductivity of air, it is approximately 30 times greater.

In order to quickly cook dry foods, such as peas and beans, they need to be soaked in water. Soaking beans leads to the absorption of moisture and removal of air, as a result of which their thermal conductivity increases by 3-4 times and the cooking time is reduced by approximately the same amount. The duration of soaking legumes depends on the water temperature: the most optimal temperature is 45-50 °C. At this temperature, the recommended soaking time is from 4 to 12 hours.

Bringing the product to readiness is accompanied by many physical and chemical changes, in particular, a change in moisture content. A decrease in moisture in the product leads to a decrease in the coefficient of thermal conductivity and a decrease in the rate of propagation of heat flow through the layers of the product that has undergone heat treatment (layers located closer to the surface). This lengthens the cooking time of the product. Therefore, one of the simplest and most effective ways to speed up the heat treatment of a product is to grind it.

Cooking of products in an atmosphere of saturated steam (heating with “hot steam”) occurs in steam ovens. Saturated steam, enveloping the product, comes into contact with it and condenses, releasing latent heat of vaporization, due to which the product is brought to readiness. Cooking products in a steam atmosphere is faster than cooking the same products in water if their geometric dimensions and shape are equal. This is explained by the fact that steam is supplied to the steam cooking chamber, the temperature of which is higher than the boiling point of water. Consequently, when cooking products in a steam atmosphere, the average temperature difference between the steam and the product is higher than the average temperature difference between boiling water and the product. This leads to an increase in the heat flow supplied per unit time per unit surface of the product, compared to the heat flow supplied by boiling water. The speed of preparation of the product is greatly influenced by its shape. The greater the ratio of the surface of the product to its volume, the faster, other things being equal, the product is prepared. For example, carrots cut into 8 mm cubes will be cooked 5 times faster than carrots cut into 8x8x50 mm sticks with the same distance from the surface to the center in the first and second cases.

Classification of cooking equipment.

Food boilers are designed for cooking broths, soups, cereals and other dishes in catering establishments. All digester boilers are classified as follows:

By type of energy used They are divided into solid fuel, electric, gas and steam.

According to the method of heating the working chamber They are divided into boilers with direct (solid fuel, gas) and indirect heating, where distilled water is used as an intermediate coolant.

By method installations of digester boilers are classified into non-tipping, tilting and with a removable cooking vessel,

According to the geometric dimensions of the cooking vessel digester boilers are classified into non-modulated, sectional modulated and boilers for functional containers. Non-modulated digester kettles have a cylindrical cooking vessel. Sectional modulated boilers and boilers for functional containers have a cooking vessel with a rectangular (in plan) cooking container. The cooking vessel of boilers for functional containers has dimensions in plan that correspond to the dimensions of the functional containers.

According to the classification, all digester boilers have alphanumeric indexing. For non-modulating boilers, the letters indicate the group, type of boiler and type of energy carrier, and the numbers following them indicate the capacity of the cooking vessel in dm 3. For example, the boiler index KPE-250 is deciphered as follows: K - boiler; P - digestive; E - electric; 250 - capacity in dm 3.

For sectional modulated ones, the letters SM are added accordingly; all other designations are the same as for non-modulating boilers.

For boilers for functional containers, the index includes the letters: K - boiler; E - electric; the figure shows the capacity of the cooking vessel in dm 3, for example, a KE-100 boiler.

The index of devices with a removable cooking vessel UEV-60 is deciphered as follows: U - device; E - electric; B - cooking; 60 - capacity, dm 3.

Boilers operating under pressure in the working chamber above atmospheric pressure are called autoclaves. Their index, for example, AE-60 stands for: A - autoclave; E - electric; 60 - capacity, dm 3.

Due to the fact that the most widely used heating method is indirectly heated boilers (non-tipping and tilting), we will consider their operation.

2. Food boilers. Schematic diagram.

The boiler (Fig. 22.1) consists of a cooking vessel 6 and a housing - an outer boiler 4, connected to each other by welding. The space between them forms a heating chamber - a steam-water jacket 2. At the bottom of the jacket there is a steam generator 1 , in which water vapor is generated, filling the boiler jacket. The outer boiler is enclosed in thermal insulation 3, which is closed by a casing 5. The top of the boiler is closed with a lid 7.

Indirectly heated food boilers are equipped with control and measuring instruments and various types of fittings: double safety valve 9, pressure gauge 10 (for electric tilting boilers - electric contact), filling funnel 11 (not available for steam boilers), level tap 12 (for steam boilers - purge), turbine valve 8 (for There is no boiler with a leaking lid, fig. 22.2).

To protect operating personnel from accidents associated with the operation of boilers, such protective equipment is provided as double safety valve(Fig. 22.3), installed on a reinforcement stand. The valve is called double because it provides double protection: it protects the boiler from explosion when the steam pressure in the steam-water jacket increases above the permissible norm and prevents deformation when the pressure in the jacket drops below atmospheric pressure.

Operating principle. The water in the steam generator is heated by heating elements to a boil, the resulting steam enters the steam-water jacket and, in contact with the walls and bottom of the boiler, condenses, releasing the heat of steam formation, due to which its contents are heated. The condensate flows down the walls back into the steam generator and turns into steam again.

Indirectly heated fire boilers work similarly. The water in the steam generators of these boilers is heated through the wall of the external boiler.

3. Non-tipping boilers. Design, principle of operation

Non-tipping boilers include boilers with a cooking vessel capacity of 100 dm 3 or more.

At catering establishments they are used with various heating methods: electric - KPE-100-1M, KPE-160-1M, KPE-250-1M; with steam heating - KPP-100-1M, KPP-160-1M, KPP-250-1M; with electrical heating for functional containers - KE-160M, KE-250M; with gas heating, sectional modulated - KPSGM-250; solid fuel - KPT-160.

Electric boilers of the KPE type. Boilers of this type (KPE-100-1M, KPE-160-Sh and KPE-250-1M) have the same design, but differ in the volume of the cooking vessel, the power of the heating elements installed in the steam generators, and dimensions. All of them refer to stationary non-tipping boilers with a leaky lid.

Boiler design KPE-100-1M(Fig. 22.4) . The boiler consists of a cooking vessel 8, connected to an external boiler 21 welding The space between the cooking vessel and the outer boiler is a steam-water jacket 22. A steam generator is located in its lower part 2 with heating elements 1 (Fig. 22.5) and a level 3 sensor, made in the form of a thermal cylinder.

Water (distilled or boiled) is poured into the steam generator through funnel 5 until it begins to flow out of the test tap 11. To maintain steam pressure in the steam-water jacket V within the range from 0.005 to 0.035 MPa, a pressure switch is used 15. and for visual control of pressure - pressure gauge 6. To relieve pressure above 0.05 MPa, safety valve 7 is used. The boiler cooking vessel is closed with a leak-proof lid 4. The lid is lowered and raised using an external counterweight 14. The angle of installation of the cover can be selected within the range of 30-90°. To drain the water, there is a drain valve at the bottom of the cooking vessel. 17. Inside the brewing vessel, the hole to the drain valve is closed with a removable filter 20. There is a filling tap for filling the brewing vessel 23.

Between the outer boiler and the cladding 19 there is thermal insulation 18 in the form of sheets of aluminum foil. The boiler casing is made of sheet steel and painted with light enamel. The main part of the electrical switching, signaling and automatic control devices is located in the form of a control station on the wall near the boiler.

The boiler is equipped with control and measuring equipment (Fig. 22.6).

In Fig. 22.7 presents equipment for automatic control of boiler operation.

In Fig. 22.8 shows the folding clamp of the boiler lid and the air valve.

Having installed the boiler, hot and cold water supply pipelines are supplied and connected to it, as well as a pipeline for discharging boiling vapors into the sewer system according to the diagram shown in Fig. 22.9.

Before turning on the boiler, the valve on the boiling vapor removal pipeline must be open, the black arrow of the pressure gauge must be at zero, the control arrow of the upper pressure limit is set to a pressure of 0.4, and the control arrow of the lower pressure limit is set to 0.15.

The control arrows are installed using a special key (as shown by the red arrow in Fig. 20.11).

To turn on the boiler, you need to press one of the “start” buttons (on the boiler or at the control station), this will turn on all six electric heaters of the boiler and both signal lamps on the control station will light up. As soon as steam appears from the air valve, the valve must be closed.

When the pressure in the steam-water jacket reaches the upper limit, 7 out of 8 electric heaters are automatically turned off. In this case, one of the signal lamps goes out.

To stop the boiler after finishing cooking, just press the “stop” button and make sure that both warning lights go out.

Before opening the boiler lid, you should carefully lift the turbine valve by the ring and release excess steam to avoid the risk of burns. The folding clamps securing the boiler lid are released one by one, turning each half a turn. After unloading the boiler from food, it is thoroughly washed with hot water, which is then removed through the drain valve.

Every day, upon completion of work, the turbine valve and steam outlet pipe should also be washed with hot water. The boiler lining is wiped with a soft cloth. The proper grounding of the boiler body and control station must be regularly checked by specialists.

Operating principle. The boiler operates in three modes: 1 - “Cooking”, 2 - “Warming up”, 3 - “Steaming”. First mode("Cooking"). The boiler turns on at full power of the heating elements. The boiler is turned on by the green “On” lamp at the control station. The automatic shutdown of the boiler due to the activation of the “dry running” protection is indicated by the red “No water” lamp. After turning on the boiler and the green “On” lamp lights up, the pressure in the steam-water jacket increases. The resulting steam rises up and displaces the air, which exits through the forcibly open safety valve 7. The safety valve handle is turned with the arrow up. As soon as the temperature of the contents of the digester reaches 80-85 ° C, steam begins to escape through the open safety valve. In this case, you need to turn the safety valve handle with the arrow down and stop the steam coming out. The steam pressure in the steam-water jacket will begin to increase and after some time will reach the upper specified limit (0.035 MPa), and the temperature inside the cooking vessel will be approximately 95°C. In this case, the pressure switch will switch the boiler to 1/8 heating element power and maintain a quiet boiling mode. If the steam pressure in the steam-water jacket drops and reaches the lower limit of 0.005 MPa, the pressure switch will again switch the heating elements to full power.

Second mode(“Warming up”). The boiler turns on at full power. When the pressure in the steam-water jacket reaches the upper limit (0.035 MPa), the contents of the cooking vessel boil, and the pressure switch turns off the heating elements.

Third mode(“Steaming”). The boiler turns on at full power, and when the steam pressure in the steam-water jacket reaches the upper specified limit (0.035 MPa), the water in the cooking vessel boils, and the pressure switch switches the heating elements to 1/8 power. If the pressure continues to fall and reaches the lower set limit, the pressure switch switches the heating elements to 1/2 power. When the upper specified limit is reached, the pressure switch again switches the heating elements to 1/8 power and so the cycle will be repeated until the boiler turns off.

4. Steam digester boilers CPP

Steam digester boilers KPP. This type of boiler is advisable to use in a public catering establishment, which is located on the territory of a plant that has its own boiler room that produces Steam for technological purposes. Boilers KPP-100-1M, KPP-160-1M and KPP-250-1M are unified with electric boilers of the same capacity. Since all KPP-type boilers have the same design and differ from each other only in the capacity of the cooking vessel, dimensions and weight, we will consider the design and principle of their operation using the example of the KPP-100-1M boiler.

Boiler design. The boiler is a prefabricated welded structure consisting of a cooking vessel hermetically connected to the outer casing. The resulting closed space between the inner and outer casing serves as a steam jacket. Thermal insulation, made of corrugated aluminum foil, is placed between the outer casing of the boiler and the lining. The upper cooking vessel with a steam-water jacket is installed on a base, the flange of which has holes for attaching the boiler to the foundation. A condensate trap with pipelines is located inside the cylindrical base. It is designed in such a way that it does not allow the passage of uncondensed steam, but only condensate. Steam enters the steam jacket through a valve. A test valve is used to remove air and condensate from the steam jacket before starting the boiler. The steam pressure in the jacket is controlled by a pressure and vacuum gauge. When the pressure in the jacket increases above 0.05 MPa, the safety valve is activated. Water is supplied to the cooking vessel through a tube. The cooking vessel is closed with a lid connected to a spring counterweight. To drain the liquid, use a drain valve, the inlet of which is closed with a mesh.

Operating principle. The amount of steam supplied from the main line into the steam jacket is regulated by a valve. The air is displaced by steam and exits through the initially open tap, and after closing it through the safety valve. To do this, its handle must be turned with the arrow pointing upward. After a steady stream of steam appears from the safety valve, its handle is turned with the arrow down and the valve closes. Pressure begins to increase in the steam jacket. By turning the valve, you can reduce the pressure increase. Pressure control is carried out according to the pressure and vacuum gauge readings. If there is no pressure control, then when the pressure reaches 0.045 MPa, the safety valve is activated and relieves the pressure. The quiet boiling mode is regulated by supplying steam to the steam jacket.

5. Electric digester boilers for functional containers (FE)

Boilers KE-100M, KE-160M ​​and KE-250M are designed for preparing side dishes, cereals, first courses, sauces, compotes and other dishes in catering establishments. The main feature of the operation of these boilers is that the cooking of products in such boilers can be carried out in functional containers placed in a cassette. The operating principle of these boilers is as follows: the product to be cooked is placed in functional containers and installed in a cassette along the guide corners. Then, using the lifting mechanism of the trolley, the cassette is lowered into the cooking vessel of the boiler.

Let us consider the design of boilers of this type using the example of the KE-250M boiler.

Boiler design. The boiler is a welded structure. Cooking vessel hermetically connected to the shell , to which the steam generator is welded . A steam-water jacket is located between the cooking vessel and the shell. Between the shell and facing sheets there is thermal insulation made of sheets of corrugated aluminum foil. Inside the steam generator heating elements are located . To protect heating elements from “dry running”, a temperature sensor-relay is used, the temperature-sensitive cylinder of which is fixed to the uppermost heating element. A decrease in the water level in the steam generator below the level of the upper heating element triggers the “dry running” protection and turns off the heating elements. Water is poured into the steam generator through a funnel , level controlled by tap . The steam pressure in the steam-water jacket is maintained at a certain range (0.0045-0.045 MPa) using a pressure switch sensor . When the steam pressure in the steam-water jacket is above 0.05 MPa, the safety valve is activated. Filling the cooking vessel with water is carried out by opening the tap . Liquid is drained from the cooking vessel through the drain valve , the opening of which is protected by a mesh (filter). To prevent burns to operating personnel when lifting the lid when the contents are boiling, steam is removed to the outside through a bypass valve. The valve has a reflector on the inside of the cover . The tight fit of the lid is ensured by hinged levers . The boiler control and alarm elements are displayed on the control panel.

Operating principle. The boiler has three operating modes: 1 - “Cooking”, 2 - “Warming up”, 3 - “Steaming”. Boiler operating modes are set manually using a switch 21. The numbers 1, 2, 3 on the switch correspond to the names of the modes.

First mode("Cooking"). If the first mode is set, the heating elements are turned on at full power, the switch is in position 1. The water in the steam generator is heated to a boil and steam displaces air through the safety valve. The valve handle should be turned with the arrow pointing up. When a steady stream of steam appears from the opening of the safety valve, the handle is turned with the arrow pointing down and the valve closes. When the pressure in the steam-water jacket reaches the upper specified limit (0.035 MPa), the pressure switch switches the heating elements to 1/6 power. If the pressure in the steam-water jacket continues to fall and reaches the lower limit (0.005 MPa), the pressure sensor-switch will switch the heating elements to full power.

Second mode(“Warming up”). The switch is set to position 2, and the heating elements are turned on at full power. When the upper value of steam pressure in the steam-water jacket is reached, the pressure sensor-relay turns off the heating elements. To turn it on again, you need to change the position of the switch.

Third mode(“Steaming”). The switch is set to position 3. In this case, the heating elements are turned on at full power, and when the upper specified pressure limit is reached, the pressure sensor switch switches the heating elements to 1/6 power. The pressure in the jacket will decrease accordingly and, when the lower specified limit is reached, the sensor-relay will switch the heating elements to 1/2 power, and upon reaching the upper specified pressure limit, it will again switch to 1/6 the power of the heating elements, and the cycle will repeat.

All KE type boilers are equipped with devices for automatic transfer of liquid from the cooking vessel into functional containers, mobile boilers, and food warmers. When pouring, the boiler lid remains tightly closed and pressed with hinged levers. Draining is carried out through the drain valve due to the fact that when the Liquid boils, excess steam pressure is created in the cooking vessel, which displaces the liquid from the cooking vessel.

The KE-100M and KE-160M ​​boilers differ from the considered KE-250M boiler in the capacity of the cooking vessels, the power of the heating elements, dimensions and weight. In terms of operating efficiency, the boilers have approximately equal indicators, but the best is still the KE-250M boiler. Its efficiency when heating from 20 to 95°C is 79.3%, while for the other two it is approximately the same and amounts to 75%.

6. Tilting boilers

Electric sectional modular boiler KPESM-60M(Fig. 22.12) is a cooking vessel 1 made of stainless steel, suspended on stands 8 and 11. A shell is welded to the outside of the boiler, to which a removable bottom is hermetically attached. Three heating elements and an electrode for protecting the heating elements from “dry running” are mounted in the bottom. The closed space between the shell with the bottom and the cooking vessel is filled with water and steam and serves as a steam-water jacket. The latter is connected by a pipe to a unit of control and measuring instruments: an electric contact pressure gauge 4, double safety valve 6 and filling funnel 5. The boiler is equipped with a level tap 9. The cooking vessel is fixed in a casing and equipped with thermal insulation. The top of the cooking vessel is closed with a lid 3 with a device 2 for lifting it and a friction clutch that fixes the lid in any position. The cabinets are a welded frame mounted on four height-adjustable legs 10 and covered with cladding. The cabinets are equipped with cast iron brackets with sliding bearings, on which the boiler rests using hollow pins. The top of the cabinets is covered with a stainless steel table.

The boiler has a rotating mechanism located in the right cabinet and representing a worm pair. The worm wheel is mounted by means of a key on a pin connected to the boiler body. A worm is engaged with the worm wheel, at the protruding end of which a handwheel with handle 7 is attached.

Dry running protection prevents the boiler from turning on if the heating elements are not completely covered with water; The boiler is disconnected from the power supply even if the water level drops to a certain limit and if the boiler overturns. If the water level in the steam generator is insufficient, the warning lamp lights up 14.

Water is supplied to the boiler from the water supply column using a rotary tap.

The left cabinet contains a panel with electrical equipment. On the front side there are: signal lamps "On" 13 and "No water" 14 and switch 12 to set the boiler operating mode.

Principle of operation. The boiler operates in two modes. In the first mode, the boiler first operates at full power, and after the pressure in the jacket increases to a predetermined upper limit, it switches to low heating (1/9 power). After the pressure drops to the lower set limit, the boiler turns on again at full power. This operating mode is used when cooking soups, borscht and other first courses. In the second mode, the boiler operates at full power until the pressure in the jacket reaches the upper specified limit. After this, the boiler heaters are completely switched off. Products are cooked using accumulated heat without consuming electricity. The second mode is used when boiling milk, cooking jelly, vegetables.

Electric boilers KPE-60(Fig. 22.13) are installed on a cast iron fork-shaped frame 10 using two hollow pins 8 and 16 connected to the outer boiler 15. Swivel mechanism 9 has the same device as the KPESM-60M boiler. To fill the cooking vessel 1 with water, a water pipe is attached to the left stand of the frame from the outside 17, equipped with a valve 18, water outlet 20 and bracket 19 for hanging the lid. The digester with the fairing 2 installed on it from the outside is closed with an easily removable lid 3. The lid has a handle in the center and a steel hook on the inside, with which it is hung on the bracket. The boiler fittings include a 7 electrical contact pressure gauge mounted on the fitting stand. 4, double safety valve 6, filling funnel 5 and level tap 11. Steam is generated at the bottom of the jacket using three heating elements 13 (Fig. 20.17), mounted on a removable bottom 14 boiler The boiler is equipped with a grounding bolt 12.

The boilers have two operating modes and are equipped with automatic regulation of thermal conditions and automatic protection of heating elements from dry running. Protection is carried out using an electrode mounted in a removable bottom 14 boiler

In Fig. 22.14 shows the frame and rotation mechanism of the KPE-60 electric boiler.

In Fig. 20.15 shows the control and measuring instruments of the KPE-60 electric boiler.

In Fig. Figure 22.16 shows a diagram for switching heating elements of the KPE-60 electric boiler.

7. Rules for operating digester boilers

Before starting cooking, check the sanitary condition of the boiler and press the safety valve lever (for tilting boilers and non-tipping boilers of the old design). For boilers KPE-100-1, KPE-160-1, KPE-250-1 and for steam boilers, it is necessary to turn the safety valve handle so that the arrow points upward. This is done in order to prevent the valves from sticking to the seat and to open the valve to remove air from the boiler jacket. The air is removed through the special air valve of the safety valve or through the safety valve (new boilers) or through the filling funnel if the safety valve does not have an air valve. Air from the jacket must be removed, since its presence in the jacket impairs heat transfer from the steam-water mixture to the boiler wall, which leads to a significant increase in its heating time and excessive energy consumption. Then check the presence of water in the steam generator. If water does not flow out of the open level tap, it is poured through the filling funnel. In this case, the funnel valve, level control valve or test drain valve must be open. As soon as water appears from the level valve or fractional drain valve, they are closed and the filling of the jacket is stopped. To prevent the formation of scale on heating elements and other heat transfer surfaces, cooled boiled water must be poured into the steam generator (the presence of scale in the case of using hard water impairs heat transfer and accelerates the failure of heating elements). After this, the turbine valve (if equipped) is washed.

A filter mesh is installed on the drain valve opening of a non-tipping boiler to protect the drain valve from clogging with product particles. When cooking first courses, the digester is filled with food and water to a level 10-12 cm below the upper edge of the boiler. The lid of the boiler is closed, after first checking the condition of the rubber gasket. The clamping bolts of the sealed cover are screwed in two steps to prevent it from skewing and breaking the bolt threads. When opening the lid, the bolts are also unscrewed in two steps.

Next, check the position of the arrows of the electric contact pressure gauge, which for tilting boilers should be set to the upper - 0.035 MPa and lower 005 MPa pressure limits. If this is not done, the arrows must be installed with a special key. When installing the arrows, the key is inserted into the hole in the center of the pressure gauge and the lever equipped with a stop is pressed. Using this lever, the arrows are moved and set to the required position. Then the boiler operating mode is set using a switch and checked by turning on the signal lamp. In the first mode of operation of the boiler, all the heating elements work first, and after its contents boil and the pressure in the jacket reaches the upper specified limit, the heating elements switch to 1/9 power; The cooking process begins. In the second operating mode of the boiler, all the heating elements are also turned on at first, and after it warms up, the boiler is automatically disconnected from the power supply, and the products are finished cooking using the heat accumulated by the boiler.

The beginning of boiling of the contents of the boiler is recognized by the rotation of the turbine valve ring (for boilers with a sealed lid). During operation, boiling vapors are discharged from the boiler into the room through a turbine valve. During operation, use a pressure gauge to monitor the steam pressure in the jacket. If the pressure rises above 0.04 MPa, the boiler is turned off.

During the work process, it becomes necessary to add products and check their readiness. To do this, first of all press the “Stop” button and disconnect the boiler from the power supply. Then, using a wooden stick, lift the turbine valve by the ring, release excess steam from under the boiler lid, unscrew the bolts, first loosening them and then unscrewing them completely, and open the lid, being careful not to get burned by the steam. Having added the products, close the lid again in the above sequence and turn on the boiler by pressing the “Start” button. You can add products to boilers with an unsealed closed lid without disconnecting the boilers from the network.

5-10 minutes before the end of cooking, the boiler is turned off (Fig. 20.18), then, carefully opening the lid, unloaded and washed with warm water with the addition of soda. The turbine valve and steam outlet pipe in old KPZ-100 boilers are washed daily, for which the valve labeled “Rinsing” is opened. The steam outlet is washed with the lid closed; The water is drained through the drain valve. The boiler is left open to dry. From the outside it is wiped with a soft damp cloth.

8. Food boilers from Metos and Falcon

Among the foreign digester boilers, boilers from the company "FALCON" (Great Britain) and the company "Matos" (Finland) should be highlighted.

Electric boilers from "FALCON" Available in two types: classic round series E-3078 and rectangular series E-3080. Each series, in turn, is divided into direct heating boilers (heating elements are located under the bottom of the boiler) and so-called dual-use boilers. In "dual-purpose" boilers, in the first case the cooking vessel can be used as a direct heating boiler; in the second case, a smaller container (liner) can be inserted into it. After placing the liner in the boiler, water is poured into it and after boiling it acts as a steam-water jacket, heating the liner with the product. The heating of the boiler is controlled by a power regulator, which allows you to effectively change the temperature of the water in the boiler from low to vigorous boiling.

The boilers have the appropriate designation: the last two digits indicate the capacity of the digester in dm 3; boilers with liners are coded using a fraction, where the numerator is the capacity of the boiler, the denominator is the capacity of the liner.

Electric food boilers from "Matos" are produced under the name "Wiking" models 4C, 6C, 8C, 12 with a capacity of 40, 60, 80 and 120 liters with intermediate coolant, respectively. The steam generator is located at the bottom, the space between the inner and outer boiler forms a steam-water jacket. The boiler has fairly effective thermal insulation, consisting of three shells, protection against “dry running”, as well as protection that turns off the heating elements when the boiler is tilted. Internal and external boilers are made of stainless steel. On the right support stand of the boiler there is a stepless power regulator with a signal lamp, a cold and hot water tap and a boiler tilt flywheel. The boiler is equipped with a double safety valve against high pressure in the steam-water jacket and a vacuum valve. The steam pressure in the steam-water jacket is monitored according to the readings of the pressure gauge.

9. Modern digesters

MBM (ITALY). A food boiler is indispensable for preparing dishes in catering establishments. The boiler is made of stainless steel 18/10. It is equipped with a built-in thermostat; the switches are made of heat-resistant plastic (Fig. 22.19).

GIGA (ITALY). Cooking kettle CPEI (Fig. 22.20). Designed for preparing 1 course at catering establishments. Water supply and drainage is carried out using a tap connected to the water supply.

PROMMASH (RUSSIA)

Cooking boilers (Fig. 22.21) with electric and steam heating or electric heating are indispensable for quickly preparing first, second and third courses in canteens, cafes, and restaurants. It is characterized by simplicity and ease of maintenance. Thanks to a well-thought-out design and the use of the most efficient modern electric heating elements, excellent distribution of operating heat is achieved. The heating temperature regulator and the valve for filling the container with water are located on the front panel. A pressure gauge located on the surface shows the pressure in the water jacket. By design, the boilers are stationary, non-tipping, equipped with safety valves in the steam jacket, which are activated when the pressure rises. Nominal volume - 60 l, 100 l. The established service life is 10 years. All products are height adjustable.

Tables 22.1 and 22.2 present the technical characteristics of digester boilers.

Table 22.1

Technical characteristics of digester boilers E100 and CPEI

Table 22.2

Technical characteristics of KPE digester boilers

Food boilers are designed for cooking broths, soups, porridges, boiling syrups and other dishes in catering establishments. All digester boilers are classified as follows.

According to the type of energy used: they are divided into solid fuel, electric, gas and steam.

According to the method of heating the working chamber: for boilers with direct (solid fuel, gas) and indirect heating, where distilled water is used as an intermediate coolant.

According to the installation method: non-tipping, tilting and with a removable cooking vessel.

According to the geometric dimensions of the cooking vessel: unmodulated sectional and modulated and boilers for functional containers. Non-modulated digester kettles have a cylindrical cooking vessel. Sectional modulated boilers and boilers for functional containers have a cooking vessel with a rectangular (in plan) cooking container. The cooking vessel of boilers for functional containers has dimensions in plan that correspond to the dimensions of the functional containers.

According to the classification, all digester boilers have alphanumeric indexing. For non-modulating boilers, the letters indicate the group, type of boiler and type of energy carrier, and the numbers following them indicate the capacity of the cooking vessel in dm.

For sectional modulated ones, the letters SM are added accordingly; all other designations are the same as for non-modulating boilers.

The index of devices with a removable cooking vessel UEV-60 is deciphered as follows: U - device; E - electric; B - cooking; 60 - capacity, dm. Boilers operating under pressure in the working chamber above atmospheric pressure are called autoclaves. Their index, for example AE-60, is deciphered as follows: A - autoclave; E - electric; 60 - capacity, dm. A special place is occupied by boilers with gas heating of the wall of the cooking vessel. Gas is the main energy carrier alternative to electrical energy. The main advantage of gaseous fuel over electricity is the low cost of the heat generated. A unit of heat obtained from gas combustion is 7...13 times cheaper than M.I. Botov. Thermal and mechanical equipment of trade and public catering enterprises: a textbook for beginners. prof. Education / M.I. Botov, V.D. Elkhina, O.M. Golovanov. - 2nd ed., rev. - M..: Publishing Center "Academy", 2006. - P. 272.. than when using electrical energy.

Among the disadvantages of gas, it should be noted that it is explosive and the possible appearance of toxic carbon monoxide (CO - carbon monoxide) in the air if the equipment is used improperly.

Modern boiler designs

Catering establishments use boilers with a cooking vessel capacity of 100 dm2 or more. Such boilers have different heating methods: electric - KPE-100-1M; KPE-160-1M; KPE-250-1M; with steam heating - KPP-100-1M, KPP-160-1M, KPP-250-1M; with electrical heating for functional containers - KE-100M, KE-160M, KE-250M; with gas heating, sectional modulated - KPSGM-250; solid fuel - KPT-160.

Electric kettles

Electric boilers of the KPE type Gaivoronsky K.Ya., Shcheglov N.G. Technological equipment of public catering and trade enterprises: textbook - M.: ID "FORUM": INFRA-M, 2008. - P. 240. have the same design, but they are distinguished by the volume of the cooking vessel, the power of the heating elements, dimensions, as well as tilting and non-tipping tipping.

The electric digester boiler KPE-100-1M is shown in Figure 1.

Figure 1 - General view of the electric digester boiler KPE-100-1M

Electric digester boiler KPE-100-1M, in accordance with Figure 1, consists of a cooking vessel 8 surrounded by a steam-water jacket, limited on the outside by an external boiler with a shell 9 and a base 10. The boiler is equipped with tubular electric heaters 1, a steam generator 2, a thermal cylinder 3, safety valve 7 and pressure gauge 6, plug 12, filling valve 13, spring counterweight 14, pressure switch 15, which serves to maintain pressure in the steam-water jacket, temperature sensor-relay 16. Plug-drain valve 11 serves to control the level of distilled water in the steam generator , poured into it through funnel 5. Tap 17 is used to drain the water. The cooking vessel is closed with a lid 4.

The tilting boiler KPESM-60 (Fig. 2) consists of a cooking vessel enclosed in a rectangular body and installed on two pedestals.

1 - cooking vessel, 2 - pressure gauge, 3 - trunnion, 4 - double safety valve, 5 - heating element, 6 - rotary mechanism

Figure 2 - Tilting boiler KPESM-60

The upper part of the boiler is made in the form of a rectangular table with a chute for draining liquid.

The cooking vessel is closed with a lid, which is mounted in racks on the table. In the lower part of the internal boiler, three heating elements and a “dry running” electrode are installed on the removable bottom. The mechanism for tilting the boiler is located in the right cabinet. To unload the boiler from cooked food, it tilts forward, and when tilted back, free access is provided for maintenance and repair of the steam generator.

On the left side there is a panel with electrical equipment and a boiler mode switch, as well as a water mixer with two taps and a rotary pipe.

The design and operation of the control and regulating valves of the KPESM-6O boiler, as well as the operating principle and operating rules are similar when working on the KPE-100 boiler.

Among the electric cooking boilers for functional containers, we can highlight the KE-250M boiler. The main feature of the operation of these boilers is that the products can be cooked in them in functional containers placed in a cassette.

The operating principle of these boilers is as follows: the product to be cooked is placed in functional containers and installed in a cassette along the guide corners. Then, using the lifting mechanism of the trolley, the cassette is lowered into the cooking vessel of the boiler.

The boiler is a welded structure. The cooking vessel 20 is hermetically connected to the shell 18, to which the steam generator 15 is welded. A steam-water jacket is located between the cooking vessel and the shell. Between the shell 18 and the facing sheets 24, 26, 28 there is thermal insulation 19 made of sheets of corrugated aluminum foil. Inside the steam generator 15 there are heating elements 16. To protect the heating elements from “dry running”, temperature sensors-relays 25 are used, the temperature-sensitive cylinder of which is fixed to the uppermost heating element. A decrease in the water level in the steam generator below the level of the upper heating element triggers the “dry running” protection and turns off the heating elements. Water is poured into the steam generator through funnel 8, the level is controlled by tap 12. The pressure in the steam-water jacket is maintained in a certain range (0.0045 - 0.045 MPa) using a pressure sensor-relay 22.

a - general view; b - diagram

1, 27 - drain taps; 2 - bypass valve; 3 - cover; 4 - tap for filling water; 5 - pressure and vacuum gauge; 6 - table; 7 - control panel; 8 - funnel; 9 - valve; 10 - reflector; 11 - lever; 12 - test and drain valve; 13 - filter; 14 - thermosensitive cylinder of temperature sensor-relay; 15 - steam generator; 16 - electric heaters; 17 - frame; 18 - shell; 19 - thermal insulation; 20 - cooking vessel; 21 - switch; 22 - pressure sensor-relay; 23 - grounding clamp; 24, 26, 28 - facings; 25 - temperature sensor-relay

Figure 3 - Electric digester boiler KE-250M

When the steam pressure in the steam-water jacket is higher than 0.05 MPa, safety valve 9 is activated. The cooking vessel is filled with water by opening tap 4. Liquid is drained from the cooking vessel through drain valve 27, the opening of which is protected by mesh 13. The tight fit of the lid is ensured by hinged levers 11. Control and alarm elements are displayed on control panel 7.

In public catering, the electric cooking device UEV-60 M has also found application. Gaivoronsky K.Ya., Shcheglov N.G. Technological equipment of public catering and trade enterprises: textbook - M.: ID "FORUM": INFRA-M, 2008. - P. 254. .

1 - tubular electric heaters; 2 - steam generator; 3 - pressure switch; 4 - rear cabinet; 5 - funnel; 6 - valve; 7 - tap; 8 - lever button; 9 - lever; 10 - mobile boiler; 11 - steam jacket; 12 - test and drain valve; 13 - steam shut-off device; 14 - plug; 15 - platform; 16 - wheel; 17 - tap for controlling the water level; 18 - dry running protection sensor; 19 - plug; 20 - lower part of the steam shut-off device

Figure 4 - Electric cooking device UEV-60M

The device is intended for cooking seasoning soups, preparing second and third courses, side dishes, stewing vegetables, as well as for transporting ready-made dishes to the distribution line, keeping them hot and distributing them to the consumer.

The device is a set with a permanently installed steam generator and a mobile boiler.

Steam digester boilers

Steam digester boilers are installed at those catering establishments where it is possible to receive steam from a factory boiler room or thermal power plant.

1 - fork-shaped frame; 2 - facing; 3 - thermal insulation; 4 - cooking vessel; 5 - axle; 6 - outer casing; 7 - steam jacket; 8 - rotary valve; 9 - cover; 10 - valve; 11 - pressure gauge; 12 - double safety valve; 13 - flywheel; 14 - blow-off valve; 15 - condensate drain.

Figure 5 - Steam digester boiler KPP-60

The steam produced in the boiler plant is supplied to the enterprise through a steam line into the jacket of the digester boiler, where it cools, condenses and, after passing through a condensate drain and condensate line, again enters the boiler room for reheating.

The KPP-60 boiler consists of an internal cooking vessel, cylindrical in shape, and an outer casing covered with thermal insulation and a casing. Steam enters the steam jacket through the steam line through the right trunnion, and the condensate is discharged at the bottom of the boiler.

The boiler is installed on a cast iron fork-shaped frame with the help of axles, which ensure its tilting using a flywheel and a worm gear.

Gas-heated boilers

Gas-heated boilers occupy a large place among digesters. Modern boilers include the KPG-40M gas digester boiler, the KPGSM-250 sectional modulated boiler, and others.

1 - cooking vessel; 2 - external boiler; 3 - thermal insulation; 4 - steam-water jacket; 5 - steam generator; 6 - axle; 7 - pedestal; 8 - gas burner; 9 - rotary valve; 10 - pressure gauge; 11 - filling funnel; 12 - level tap; 13 - door; 14 - gas automation unit

Figure 6 - Tilting gas digester boiler KPG-40M

The gas digester boiler CNG-40M is similar to the boiler CPG-60M. They have a fundamentally identical structure and differ only in the capacity of the cooking vessel and weight.

The KPG-40M boiler consists of an internal cooking vessel and an outer casing mounted on a cast iron fork-shaped frame using two axles, which ensure tilting using a worm gearbox.

Under the steam generator there is a gas burner chamber in which an injection burner is installed. Primary air is supplied to the burner by a regulator made in the form of a washer. Secondary air enters the burners through an annular gap at the base of the boiler.

Combustion products from the gas burner chamber are discharged into the chimney.

The boiler is equipped with control and safety fittings: electric contact pressure gauge, double safety valve, air valve. Level tap, filling funnel, as well as gas automatic safety and regulation.

Of the special safety valves, we can highlight the turbine type valve, most often used in boilers, which ensures the safe operation of hermetically sealed working chambers (cooking vessel) at excess pressures up to 2.5 kPa (0.025 ati).

The turbine valve is installed on boilers in the central part of the hermetically sealed boiler lid.

The valve consists, in accordance with the figure, of a body and a vertical spindle 3 with a ring in the upper part, by which the turbine 2 is lifted when it is necessary to release steam from the boiler. A turbine with helical grooves is installed at the lower end of the spindle. The housing contains an upper valve 5, a lower valve 7, a retainer and a fitting 6 for connecting to the steam outlet. The bottom valve has grooves to remove air and steam with a slight increase in pressure.

On the inside of the lid there is a reflector 8, designed to protect the turbine valve from clogging with small food particles. When the pressure under the boiler lid increases, the steam lifts the turbine and, passing through the screw grooves, causes it to rotate, as a result of which part of the steam escapes into the environment through the top, and part into the steam outlet through the fitting. The release of steam from the turbine valve signals the beginning of boiling of the liquid in the boiler. Every day, at the end of cooking, the turbine is removed, washed, dried and put back in place. Remove the turbine from the socket after the latch is pulled out.

1 - boiler cover; 2 - turbine; 3 - vertical spindle; 4 - clamp; 5 - top valve; 6 - fitting for connecting to the steam line; 7 - bottom valve; 8 - reflector

Figure 7 - Turbine valve

The KPGSM-250 sectional modular gas digester boiler is more productive due to its larger container capacity.

The outer boiler has a rectangular shape, inside which there is a cooking vessel in the shape of a horizontal half-cylinder. The vessel is closed from above with a lid 6, equipped with a counterweight and hinged bolts 4.

1 - drain valve; 2 - level tap; 3 - valves on cold and hot water pipelines; 4 - hinged bolts; 5 - rotary valve; 6 - cover; 7 - pressure gauge; 8 - start button; 9 - main burner tap

Figure 8 - Gas modular boiler KPGSM - 250

Alfol is used as thermal insulation. The external boiler is connected by welding to a five-pocket steam generator. The outer pockets of the steam generator have a lower height than the middle ones. Three middle pockets form two identical combustion chambers, each of which contains one tube of a two-pipe nozzle of an injection multi-nozzle burner, which has a mixer with a peripheral gas supply. During operation of the boiler, three central pockets are heated by torches of the burner flame, with the middle pocket on both sides. The combustion products, washing the two outer walls of the outermost central pockets and all the walls of the remaining pockets, give off heat to the water in them, which begins to boil. The resulting steam fills the steam-water jacket, comes into contact with the walls of the cooking vessel and condenses, releasing heat to heat the contents of the boiler. Boiler capacity 250 l. Autoclaves, electric cooking devices such as UEV-60M, steam cookers, etc. are also used in public catering.

Patent review

Vacuum evaporation plant for vegetable oils, in accordance with patent No. 2288256 by I.V. Shchepkina and co-authors, relates to the food industry, namely the oil and fat industry. A vacuum evaporation plant for vegetable oils consists of a vacuum apparatus, a condenser and a vacuum pump. The device differs in that the vacuum apparatus is a horizontal vessel made of a continuous pipe in the form of several identical cylinder segments connected to each other with a large cylinder segment connected to the coolant circulation circuit. In this case, along the axis of the large segment of the cylinder, shafts are placed with the possibility of rotation in different directions, to which snake-like perforated blades are attached. The invention makes it possible to reduce the heating temperature of the oil and increase the evaporation surface.

An evaporator is known, represented by patent No. 2288018, which relates to the field of chemical technology and can be used for concentrating solutions and suspensions to produce process steam or for low-temperature concentration of solutions and suspensions under vacuum conditions to obtain pure condensate. The evaporator contains a vertical or inclined body made of thermoplastic material and has a honeycomb cellular structure. The body of the apparatus is made multi-sectional with the possibility of sequential movement of the evaporated liquid from section to section with multiple circulation of liquid inside each section. Evaporation is carried out by “slug” or ascending thin-film boiling of the liquid. A large number of internal partitions ensures a developed specific heat transfer surface and high strength of the apparatus against the influence of external or internal pressure with a small thickness of the partitions. The invention makes it possible to increase the stability of the evaporator to changes in operating mode.

Feasibility study of the project topic

Boilers with gas heating of the walls of the cooking vessel have an advantage over electric ones, since they are cheaper due to cheaper fuel - gas. A unit of heat obtained from gas combustion is 7...13 times cheaper than M.I. Botov. Thermal and mechanical equipment of trade and public catering enterprises: a textbook for beginners. prof. Education / M.I. Botov, V.D. Elkhina, O.M. Golovanov. - 2nd ed., rev. - M..: Publishing Center "Academy", 2006. - P. 272.. than when using electrical energy. With a gas boiler capacity of 250 liters, heating duration is 60 minutes, gas consumption during the heating period is 4.2 m3/h, which corresponds to the power of heating elements (in the combustion chamber) of 46.6 kW.

At the same time, the power of heating elements of electric boilers is 30 kW with the same volume of the cooking vessel and heating time as that of the KPGSM-250 boiler. Such a high combustion power of a gas boiler is explained by its lower efficiency compared to the efficiency of electrically heated boilers. The efficiency of the KPGSM-250 boiler is 60 - 65%.

This low efficiency value is explained by large heat losses with exhaust gases. In cooking mode, gas consumption is 0.7 m3/h, which corresponds to a heating element power of 7.7 kW. However, the cost per unit of heat generated by gas is much cheaper, which covers the costs.

Objectives of the project on the topic "Modernization of the gas sectional modular boiler KPGSM-60"

The task provides for the modernization of the gas sectional modular boiler KPGSM-60. The development of the project made it possible to improve the spring device of the lid fixation system and the clamping device and to implement the design of the conical part of the boiler with fixation of the vertical position with a stop (section G-G).

Food boilers belong to the category of thermal technological equipment and are intended for boiling water and boiling food. Simply put, these devices are used for cooking food in large quantities. What is special about digester boilers and how do they work? More on this later in our article.

Differences from traditional gas stoves

It is worth noting that this technological equipment is not at all similar in design to modern ovens and stoves that we are used to seeing in the kitchen. The main feature of digester boilers is the scale of cooking. Ordinary home stoves cannot cook food so quickly, and besides, when using such equipment, control over the entire process can easily be exercised by one person. Thus, the digester boiler significantly saves time and minimizes human resources. Of course, the size of such devices is several times larger than the dimensions of a conventional stove, so it is simply impractical to use them for domestic purposes, and there is no point in turning it on for 2-3 liters of food (this is 1/100 of everything that it should process).

Application

Often such tools can be seen in canteens at industrial enterprises with more than 100 employees. In such containers, first and second courses are quickly prepared, vegetables are boiled for salads, as well as semi-finished products are prepared. In addition, food kettles do an excellent job with side dishes, sauces, hot drinks and even sweet dishes.

Operating modes

This tool can operate in several operating modes. This includes cooking food, reheating it and steaming it.

Varieties

At the moment, there are several types of these devices, namely:

• Tilting and non-tipping digester boilers.
• Stationary and mobile.
• By type of heater - electric, steam, gas and fire.

Naturally, the most versatile equipment is a mobile boiler with a tilting container. However, the cost of such a device is hundreds of thousands of rubles.

It is worth noting that, despite the widespread use of gas stoves, an electric drive is most often used on digester boilers. Why? The fact is that, thanks to this heating method, you can regulate the temperature of the container in several ranges. Gas instruments either have two degree modes or do not have them at all, that is, how much the side dish or water heats up, this will be its temperature.

Work algorithm

As for the principle of operation, the digester boiler (including KPEM 250) works as follows. When heating the coolant (the so-called heating element - it is located in the “jacket” of the device), heat is generated between the walls of the vessel, which are most often filled with air or water. So - with increasing temperature on the walls of the boiler container, the heating of the liquid itself, semi-finished products and other food increases. As you can see, the operating principle of this device is not that complicated.

How to combine mass cooking of huge volumes of food and get excellent results? Professional modern food boilers from the WhiteGoods online store know the exact answer to this question. Heavy-duty, convenient and mega-productive - they will instantly turn into your tireless miracle helpers in the kitchen. The level of their technological capabilities and excellent optimization for the culinary needs of modern catering are amazing.

Buy a steam digester: discover the secrets of flawless preparation of delicious dishes!

Modern kitchen equipment is developing by leaps and bounds. Electric food boilers combine a lot of undeniable advantages and look extremely popular in kitchens of any size: from the catering department of a school, kindergarten, sanatorium or hospital, to a huge factory canteen or the food galley of a liner. They don't just simplify the food preparation process and relieve the burden on staff. A gas or steam digester boiler will help practically automate cooking, and due to timers, various programs and recipes, a built-in stirrer or a powerful mixer (with the ability to beat 140 rpm), removable scrapers, etc., it will absolutely eliminate the human factor, such as burnt food, overcooking food and so on. Any programmed process can be changed to suit your requirements.

The line of units is conventionally divided into two categories: stationary and tilting (inclined) cooking boilers. The latter have a manual or automatic mechanism for emptying the bowl. Digesters can operate either from electricity or from gas, and according to the method of maintaining temperature, they are divided into devices with direct and indirect heating. The steam digester boiler boasts a unique function “Steam jacket heating” (steam-water jacket). It is ideal for recipes with a thick consistency and will prevent food from sticking to the walls of the container. Such models are beneficial by reducing energy costs and drinking water consumption. A food boiler with a stirrer will create additional convenience in large-scale cooking. Using such equipment is very easy and convenient.

Prices of digester boilers

As a rule, the more modern achievements and functionality are implemented in the equipment, the higher the price of the digester. To a large extent, the cost depends on performance, or rather the ability to accommodate an impressive amount of ingredients. You can choose a professional digester with a stirrer for simultaneous cooking of volumes from 27 to 400 liters. The range of dishes prepared in the devices is extremely rich. The capabilities of the units are not limited to soups, broths, side dishes, sauces, cereals, purees, meat stews, compotes, jelly or whipped desserts. An electric cauldron with a nominal temperature of up to 300ºC will perfectly fit into the concept of a restaurant of Uzbek cuisine.

In conditions of acute shortage of time, a gas digester boiler with an autoclave will become an indispensable acquisition for catering establishments. Under high pressure, food will not only cook much faster, but will also retain more beneficial nutrients. A food boiler with a special “liquid ice” system will cool cooked food in record time, down to +3°C. The reliability and durability of the food boiler is guaranteed by a vandal-proof, all-metal, massive body made of anti-corrosion steel (cast iron, alloys). The rational design and smoothed internal corners will make washing and cleaning easier.

Where to buy food boilers?

Do you want to experience the maximum benefits from using thermal equipment of this class? In this section of the WhiteGoods online catalog you can buy electric digesters of exceptionally high quality, from the world's best manufacturers in Finland, Germany, the USA, Italy and the Russian Federation. Highly productive, cost-effective, safe and incredibly reliable - they will cope best with food preparation in public catering volumes.
Place your order. Please yourself with the guarantee of a successful purchase. Expectations will be met!