Coursework on the topic "Heat supply of the city district" with calculations

Contents

CONTENTS:

Source Data

Calculation of heat loads of the area

2.1. Heat flow rate for heating and ventilation of residential and public buildings

2.2. Average heat flow to hot water supply

2.3. Maximum heat flow to the hot water supply of residential and public buildings

Schedule of heat consumption by duration of ambient air temperatures

Hydraulic calculation of heat networks

4.1. Preliminary hydraulic calculation

4.2. Basic Design Dependencies

4.3 Procedure for hydraulic calculation of thermal pipelines:

4.4 Final Hydraulic Calculation

Calculation of throttle diaphragms

Piezometric Plot

Selection of mains and makeup pumps

Selection of elevator for building No.

. Calculation of compensator U-shaped departure

. Calculation of central quality control schedule

Diagram of coolant flow rate versus ambient air temperature

1 Initial data

Settlement: Nizhny Novgorod

The estimated temperature of the coldest five-day period: 31 ° С.

Estimated winter ventilation temperature: 17 ° С.

Heating period:

duration: 231 days,

average outside temperature during the heating period: 3.2 ° С

Average wind speed in January V = 5.1m/s

Heat Source: Heating Boiler House

Heat supply system: closed double-tube.

Design parameters of coolant:

Type of gasket: underground.

Calculation of heat loads of the area

Maximum heat flows for Qomax heating, Qvmax ventilation and Qhmax hot water supply of residential, public and industrial buildings should be taken when designing heating networks according to the relevant projects. Heat flows in the absence of heating, ventilation and hot water supply projects are determined by:

Piezometric Plot

Piezometric graph allows: to determine heads in

supply and return pipelines, as well as located head in

Any point in the heat network taking into account the terrain available

head and height of buildings, select circuits of consumers connection;

select automatic controllers, nozzles of elevators, throttling devices for

local heat consumption systems; select the network and make-up

pumps.

Piezometric graphs for hydrostatic and

hydrodynamic modes of heat supply system. For the beginning

coordinates in backbone networks receive the location of the CHP. In

accepted scales are used to construct route profile and connected heights

consumers. The zero elevation of the ordinate axis (head axes) is usually taken as the elevation of the lowest point of the heating line or the elevation of the network pumps. A static head line shall be built, the value of which shall be higher than local heat consumption systems by not less than 5 m, ensuring their protection against "baking," and at the same time shall be less than 10 m (or more) of the maximum working head for local systems.

Then, pressure graphs for hydrodynamic mode are started. Required head is deposited on ordinate axis at suction branch pipes of network pumps (30-35 m) depending on pump grade. The pressure and temperature of the water at the suction pipes of the main, make-up, pumping and mixing pumps shall not be lower than the cavitation pressure and shall not exceed the permissible values for the strength conditions of the pump structures.

Then, using the results of hydraulic calculation, the line is built

reverse line head losses.

Then the line of the located head for

heat supply system of the calculation quarter, the value of which can be

be accepted 20 m.

The feed line head loss line is then constructed.

Piezometric graph at change of make-up head

the pump may be moved parallel to itself up or down if

there is a risk of "bare" or "crush" local systems

heat consumption.

In this case, it is necessary to take into account that the head on the suction

mains pump nozzle does not exceed limit value for accepted

pump grades to both minimum and maximum.

Under the piezometric graph there is a straight single-line

flow diagram with branches, indicate the numbers and lengths of sections,

diameters of pipelines, coolant flow rates, located heads

at node points. On piezometric diagram of main line

the design branch is plotted.