Spray dryer design SFB -9200

Contents

Summary

Introduction

1. Status of the question. Overview of Existing Designs

1.1 Dryers used in industry

1.2 Patent search result

2. Feasibility study

3. Description of the process, design and principle of operation

4. Calculation of drying unit

4.1 Calculation of basic parameters of wet material

4.2 Calculation of material balance by solid material

4.3 Calculation of material balance by drying agent

4.4 Calculation of thermal balance

4.5 Calculation of spray dryer

4.6 Calculation of the colour

4.7 Calculation of cyclones

4.8Selecting Fans

5. Rules of installation, repair and operation

6. Occupational safety

6.1 Analysis of potential hazards and hazards

6.2 Characteristics of toxicity of substances and materials

6.3 Microclimate Requirements

6.4 Lighting Requirements

6.5 Industrial noise and measures to reduce it

6.6 Vibration sources, measures to reduce them

6.7 Ensuring Electrical Safety

6.8 Selection of barriers, safety devices

6.9 Fire and Explosion Safety

6.10 Development of safety measures during operation of the facility

6.11 Safety measures during electric welding works in the drying compartment

7. Energy and resource saving

Summary

In the diploma project, the design of the drying plant with an improved drive was developed. To carry out the development, we conduct a patent search in which we consider analogues of known models of technological equipment. In the development process, it is also possible to apply the creation of new structures based on the principle of action, based on the use of modern achievements in science and technology, best practices, inventions and rational proposals. The explanatory note describes the device and the principle of operation of the plant, calculations of the material and thermal balance were made, types of drying plants were considered, and patents were sought in the field of drying plant devices. To show the economic effect of the development being implemented, we are conducting a feasibility study of the developed apparatus. The explanatory note also describes the requirements for labor protection during the operation of the drying plant, and is calculated.

Introduction

Today, spray dryers are used in all areas of milk processing, such as:

- whey drying

- milk drying

- buttermilk drying

- drying of whole milk substitute

- drying of defatted milk

All dryers embody a modern level of development. They can be operated continuously, ensuring maximum safety and efficiency.

The constant rationalization and automation of dairy plants set the task for engineers to improve the old ones and develop new technological processes. Spray dryers are important in this "rethinking."

The main idea of ​ ​ modernizing the spray dryer is to increase its productivity and reduce drying time.

The spray dryer being developed will have a higher output than the analogue, the power consumption will not change, and the profit of the enterprise will increase, as the drying time will decrease significantly. This is achieved by increasing the speed of the discharge and exhaust fan motor.

1 Status of the question. Overview of Existing Designs

During spray drying, the material is dispersed into particles (droplets) of very small size (10100 μm), which significantly increases their contact surface with the drying agent (evaporation surface) and accordingly increases the drying intensity. In this method, the duration of drying and the residence time of the material in the drying zone of the apparatus is 530 s. Under these conditions, sputtering hydrodynamics (character, particle speed, etc.), which affects the heat and mass exchange during drying, becomes crucial; in this case, mass exchange (reduction of particle size and mass as a result of evaporation) in turn affects the hydrodynamics of the process.

The specific conditions of spray drying of materials give rise to a number of characteristic advantages of this drying method, which include:

1) high quality of the dried product, the temperature of which in a significant part of the process does not exceed the temperature of the wet thermometer, wherein qualitative and quantitative indicators (particle size, bulk density of dry powder, final humidity and temperature) can be controlled;

2) absence of necessity of additional grinding of finished product, its high solubility;

3) significant initial humidity of products (solutions) and quite low final humidity ("sticky" amorphous products, for example, digestions in the form of pulp or paste, can also be dried);

4) high resistance of the dryer enclosures, since the wet material does not contact them;

5) sufficient reliability of dust collecting devices (battery cyclones, bag filters, electrofilters, scrubbers), which prevents dust from entering the room, etc.;

6) high productivity of plants, which contributes to the improvement of their technical and economic indicators, etc.

In addition, the drawbacks inherent in spray drying should be noted:

1) significant specific dimensions of plants operating in soft modes;

2) complexity and high cost of equipment for spraying products and collecting dust;

3) relatively high energy costs (heat and electricity).

In this regard, the intensification of heat and mass exchange during spray drying becomes important, which will contribute to better use of the drying agent; use of a drying agent in some cases; application of evaporative drying method of dehydration of solutions with low initial concentration and drying with multiple spraying and recycling of solution.

Spraying of liquid in dryers can be carried out by various methods and with the help of different devices, of which the following have the most application:

- centrifugal disk sprayers;

- mechanical (hydraulic) nozzles;

- pneumatic nozzles;

- ultrasonic spraying.

Usually, the process of spraying liquid entering the drying chamber from the slot nozzle consists of a number of phenomena: conversion (deformation) of the liquid jet into film (threads) in the spraying device; disturbances on the surface of this film when it leaves the sprayer due to a change in speed and the influence of the environment (air); breaking the film into individual droplets by surface tension; coalescence of droplets upon impact, the nature of which is due to the spraying method and the design of the sprayer.

According to this, a number of requirements are imposed on the sprayers, and in particular, ensuring the optimal shape of the spray flare and uniformity of the droplets of the required dimensions, operational reliability and ease of maintenance (preventing clogging of the outlets, especially when spraying coarse suspensions), high throughput at the minimum possible power consumption, etc.

The energy consumption during spraying is due to the operation of deformation of the liquid flowing at a significant speed; overcoming surface tension forces when forming an interfacial surface (droplets) and viscosity forces; reporting kinetic energy drops and overcoming hydraulic resistances.

One of the stages of production of dairy preserves is drying. This process step can be performed in the following units:

5 rules of installation, repair and operation

Installation of dryer equipment shall be carried out with the participation of the manufacturer's foreman.

The customer shall prepare the drying units supplied for installation by the units in-house.

Foundations and supporting steel structures shall be accepted for installation in accordance with the requirements of SNiP chapters.

When installing devices on reinforced concrete foundations or brickwork, adjustment screws or rigid concrete supports made on the foundation are used as supporting elements for their reconciliation.

High elevations of rigid supports shall correspond to design elevations of support surfaces of installed equipment.

Adjustment screws are used as support elements for installation and alignment of devices on metal structures. After completion of alignment, flat metal liners (thickness equal to dimensions of clearances) are laid in gaps formed between supports of devices and metal structure near fastening bolts and connected to metal structure by electric welding.

The following deviations from the design ones (if there are no instructions in the manufacturer's technical documentation) are allowed for actual indicators of reconciliation and assembly of mechanisms:

- by location of axes in the plan 10 mm;

- by height elevation 10 mm;

- by vertical axis of the device 0.3% of height, but not more than 35 mm;

- 1 mm horizontal of the base plate per diameter of the spray mechanism flange;

- aligned in terms of spraying mechanism and gas duct head 15 mm;

- vertical axis of driven shaft (for dryers with scraper device) 0.3 mm per 1 m;

- by value of large and small diameters of conical part of body 3 mm;

- non-flatness of the support for the conical part of the housing 5 mm at a length of 3 mm;

- horizontal support 15 mm per diameter;

- in horizontal direction of welded joint between conical and cylindrical parts of housing 15 mm its diameter;

- by coaxiality of exhaust pipe and dryer housing 5 mm;

- perpendicular of gas duct sections 5 mm per diameter;

- by coaxiality of gas duct and its outer cylinder 2 mm;

- by coaxiality of assembled gas duct and dryer housing 5 mm.

Depending on the lifting machines available on the installation site, the presence of platforms near the foundations for their installation, the degree of construction readiness of buildings and other factors, two methods of installation of drying units coming into installation by units can be used:

first - installation with preliminary consolidation of units into units at the assembly site;

the second - installation of units supplied by the manufacturer directly on the foundation.

All motors, starters and control panel shall be grounded. It is necessary to carefully monitor the serviceability of the grounding devices.

The cooler operation consists in timely and high-quality inspections and repairs of the units, checking for lubrication, etc.

The cooler belongs to the IX category of the repair cycle (IX).

Structure of PPM:

K-O-T-O-T-O- T-OTOT-O-S-O-TO-TO-TO-CURRENT,

where: K, C, T, O - respectively major, medium, ongoing repairs and inspections.

Inspection is a set of control operations carried out to check the readiness of the machine for use. Inspections are carried out before the start of work.

Ongoing repairs are carried out on the spot without a long shutdown of production.

The average repair covers a larger amount of work. It provides for partial disassembly of the machine, replacement of worn-out parts, regulation. Oil filling, etc.

Overhaul includes complete disassembly and defecation of all parts of the machines.

6 Occupational safety

According to article 221 of the Labour Code, labour protection is a system for ensuring the safety of life and health of workers in the course of their work, which includes legal, socio-economic, organizational, technical, psychophysiological, sanitary, medical and preventive, rehabilitation and other measures and means.

Healthy and safe working conditions contribute to increasing the productivity, satisfaction of workers with their work, creating a good psychological climate in labor collectives, which leads to a decrease in staff turnover and the creation of stable labor collectives.

The shortcomings in the work on labor protection cause significant economic losses. The incidence and injuries of workers, the cost of compensation for work in unfavourable working conditions lead to a deterioration in the economic results of the enterprise.

In this section we are working on the issues of labor protection of the dryer under development.

6.1 Analysis of potential hazards and hazards

The development of measures to ensure the safety of working conditions is carried out from the point of view of the possibility of potential hazards and hazards.

The equipment under development uses parts and assemblies that carry danger during operation and operation of the equipment. All factors relate to physical factors. Hazards include:

Electric shock;

Noise, vibration, explosion, dust.

A number of engineering solutions are provided in the dryer to eliminate hazards.

6.2 Characteristics of toxicity of substances and materials

Toxic substances are not used in the manufacture and operation of the dryer, so no additional safety measures are required in this area.

Repair and welding work in a dusty or dirty installation is not allowed, since the ignition of dairy dust carries a health hazard, so the installation is regularly thoroughly washed.

Washing all parts in contact with the product after drying is mandatory.

It is forbidden to leave the drying unit contaminated even for a short time, as this will lead to the formation of difficult to remove precipitation, which can disable the product supply system, as well as reduce the productivity of the drying unit and other drying process modes.

Timely and thorough washing is also necessary to comply with sanitary regulations.

After the drying process is completed, a non-disassembly automatic washing of the drying unit is carried out. At the same time, the entire installation is connected to the system for non-disassembly washing or looped to the balancing barrel. The direction of movement of water and detergent solutions is similar to the drying process. As detergent solutions, soda ash, detergent "Axon," "Vimol," "Moitar," belonging to hazard class 3, can be used.

6.7 Ensuring Electrical Safety

Electrical installations in case of improper use carry an immediate danger to the health of workers, which causes the need for grounding.

There are 3 hazard classes of premises. The workshop where the machine is located belongs to the 1st class - a room of increased danger in the presence of conductive dust.

The widespread use of electricity in all sectors of production and in everyday life requires knowledge of certain rules for the safe handling of electricity, without which it becomes dangerous to human life and health.

To avoid accidents caused by electric shock, it is necessary to clearly understand the danger of electric current, to firmly know and strictly comply with the basic rules for the safe use of electricity, to know how to protect against electric shock.

Current passes through the human body when a person simultaneously touches two points between which there is voltage. Touch can be

- bipolar (touching two different phases of the system),

- single-pole (touching one phase when a current passes through a person into the ground).

Electric shock can occur:

- in case of direct contact of a person with current-carrying parts of electrical equipment, which are energized;

- in contact with structural metal parts of equipment accidentally energized due to insulation damage;

- during short circuit of electrical circuit.

Protection against electric shock is performed in the following directions:

- insulation, enclosures and concealment or inaccessible arrangement of live parts of equipment;

- application of protective grounding of electrical equipment housings;

- use of fuses and circuit breakers, which switch off the unit in case of abnormal operation;

- Use of individual isolating means of protection;

- application of reduced voltage.

6.8 Selection of enclosures, safety devices.

Since in the developed installation there are rotating parts, when using this equipment, protective fences (casings) are mandatory used, as well as protective fences are installed along the perimeter of the machine. For protective fences, blocking devices are used that exclude the possibility of switching on the process equipment in the presence of free access to hazardous areas, as well as alarm and remote control means.

Also for all equipment, package machines - starters equipped with short circuit protection should be used.

6.9 Fire and Explosion Safety

Fire safety is the condition of an object in which the possibility of fire is excluded, and in the event of its occurrence, dangerous factors are prevented from affecting people and material assets are protected.

The fire protection system is a set of organizational measures and technical means aimed at preventing the impact of dangerous fire factors on people and limiting material damage from it, as well as eliminating the possibility of fire.

The category of production according to the degree of explosion and fire hazard according to TKP4742013 "Determination of the category of the room according to the degree of explosion and fire hazard" corresponds to "B."

Classification of production premises according to PUE:

1. By the degree of electrical hazard - especially dangerous.

2. Class according to environmental conditions - PII;

Degree of motor protection as per GOST 17494 - 87 is not lower than R 54.

In accordance with item 7.10 of PPB RB 1.0194; Item 2.10 SNiP all door openings of dry defatted milk drying shop, where the drying unit is located, are protected by doors with fire resistance rating of at least 0.6 hour.

The design provides for the installation of an autonomous fire detector in the workshop, as well as light indicators of spare outputs. A plan has been developed to evacuate people in the event of a fire with an exit designation.

Also installed in the room are carbon dioxide fire extinguishers brand OU10, fire shields containing luggage, a shovel, an ax and a box with sand, as well as fire cranes.

General fire safety measures during operation of the dryer:

compliance of equipment operation mode with passport data and process regulations (temperature, working tool speeds, etc.);

timely and high-quality lubrication of bearings and mechanisms of the machine;

reliable sealing of movable and fixed connections;

preventing accumulation of static electricity charges by grounding;

compliance with safety rules when stopping the classifier for inspection and repair;

application of marking and distinctive painting of process pipelines;

timely inspection and execution of PPM schedules, fulfillment of maintenance personnel training requirements.

By the time of commissioning of the object the equipment, devices and protections have to be painted in alarm identification colors: in red color - buttons, switching off levers, prohibition signs, tanks with flammable contents, internal surfaces of casings, protections, cases of electric devices, the fire equipment and stock; green - prescriptive signs, emergency exit doors, first-aid kits.

Since at this stage of the development of science and technology it is impossible to create an absolutely safe technical facility, it is necessary to teach maintenance personnel safe working methods. To solve this problem, we will develop an instruction on labor protection during operation of the drying plant.