RU2386818C2 - Gas turbogenerator - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: gas generator is intended for recovery of potential excess energy of natural gas pressure in main pipelines and comprises tight housing with covers, turbine, electric generator, bushes, inlet and outlet branch pipes. Housing has through chamber with inlet and outlet on opposite sides. Turbine and electric generator are linked up and arranged inside said housing. Covers are arranged at the housing chamber inlet and outlet. Inlet branch pipe is arranged on housing chamber inlet cover. Bushes are arranged on the housing and coupled with electric generator. Gas turbogenerator additionally comprises regulator, gate and heater. Turbine, electric generator, housing with bushes, outlet branch pipe and gate are integrated into a module. Gas turbogenerator comprises also at least two modules with their housings interconnected so that cover on inlet into first module housing, while cover on outlet from the chamber is arranged on the last module housing to form tight chamber of modules. Regulator is arranged on inlet branch pipe located on the chamber inlet cover. Every gate is arranged on separate module housing via outlet branch pipe. Heater is located behind the last module gate, connected thereto.

EFFECT: higher efficiency.

7 cl, 1 dwg

Description

The invention relates to devices for utilization of potential excess pressure energy of natural gas (GHG) when installing it in a piping system between high and low pressure pipelines with electricity generation. There is a known tendency to replace pressure reducers at gas distribution stations (gas distribution stations) and gas control stations (gas distribution stations) with turbine expanders to generate electricity through the use of differential pressure on gas distribution stations or hydraulic fracturing, the value of which can reach 5 MPa.

One of these installations, adopted as an analogue, is described in the book “Energy-saving turbo-expander units”, Stepanets AA, Moscow, Nedra, 1999, p.11, where the turbo-expander is connected to the electric generator through a mechanical gearbox. As a result, a decrease in the GHG pressure in the turboexpander gives a positive effect - electric energy due to the power generated by the turboexpander. The disadvantage of this technical solution is the use of a mechanical gearbox, which reduces the efficiency of power generation and reduces the reliability of the installation.

To eliminate these shortcomings in another analogue (Turbo expander installation, patent for invention RU 2317430 C1, MKP F02C 7/28 of 06/09/2006) the use of a mechanical gearbox is excluded due to the use of a high-speed electric generator. In addition, the operation efficiency of the installation is enhanced by the use of magnetic bearings and the efficient disposal of external GHG leaks. However, in the absence of the need to heat the GHG in front of the expander, the presence of external leaks reduces the efficiency of power generation. GHG heating with a heat exchanger also reduces the reliability and environmental performance of the installation.

The well-known "Gas turbine generator", according to patent RU 2151971 C1, MCP 7 F25B 11/00 from 10/30/1997, adopted as a prototype. The gas turbine generator comprises an input device with a nozzle, a sealed housing with covers with a turbine and an electric generator placed therein, mechanically connected by a shaft. Here, the housing has bushing insulators connected to the electric generator and is equipped with an outlet pipe, the gas turbine generator being installed between the high and low pressure lines.

The use of a sealed chamber in which the turbine and the electric generator are located completely eliminates external GHG leaks through the seal along the turbine shaft. The operation of the gas turbine prototype is as follows. High pressure gas enters the sealed chamber, passes through the turbine, where its pressure and temperature decreases, flows around the generator, cools it and leaves the chamber. The mechanical energy generated by the turbine is transformed into electrical energy in the generator.

The disadvantage of the technical solution for the prototype is a narrow pressure differential range at which the turbine can operate efficiently due to:

- unacceptably low reduction in the temperature of the GHG in the low-pressure line with increased pressure drops;

- the impossibility of the effective use of high pressure drops in one turbine.

The technical task of the proposed solution is the efficient use of the utilization of potential excess pressure energy of natural gas with high environmental performance and high reliability in the entire pressure range used in NG piping systems.

The problem is solved in that the gas turbine generator contains a sealed enclosure with covers, a turbine, an electric generator, bushing insulators, inlet and outlet pipes. The housing has a through cavity provided with an entrance and an exit from opposite sides. The turbine and the electric generator are mechanically interconnected and placed in the body cavity. The covers are located at the inlet and outlet of the body cavity. The inlet pipe is located on the cover of the entrance to the cavity of the housing. Bushing insulators are mounted on the housing and connected to an electric generator.

In accordance with the invention, the gas turbine generator further includes a regulator, a tap, a heating unit. A turbine, an electric generator, a housing with bushing insulators, an outlet pipe and a crane are combined into a module. The gas turbine generator contains at least two modules sequentially interconnected by bodies. The cavity entry cover is mounted on the housing of the first module, and the cavity exit cover is mounted on the housing of the last module to form a joint sealed cavity of the modules. The regulator is installed on the inlet pipe, which is located on the lid of the entrance to the cavity. Each crane is mounted on the housing of a separate module through the outlet pipe. Behind the tap of the last module, the heating unit is connected in series.

Using a regulator and cranes allows you to set the optimal mode of operation of the turbines in conditions of changing gas parameters of high and low pressure lines. The presence of cranes also allows you to change the number of working modules depending on the requirements of consumers.

The use of a gas heating unit on the last module with more than one module allows the invention to be used in pipeline systems with high pressure drops, where the temperature of the gas behind the turbines decreases to unacceptably low values for consumers.

The combination of a turbine, an electric generator, a housing with bushing insulators, an outlet pipe and a valve in a module, the introduction of an additional one or several modules allows us to expand the field of possible effective application of the invention to pipeline systems with large pressure drops between high and low pressure lines by increasing the efficiency of turbines with more optimal distribution of the differential pressure between them.

This allows you to effectively utilize the potential excess pressure energy of natural gas with high environmental performance and high reliability over the entire pressure range used in GHG distribution systems.

The development and refinement of the above set of essential features is given below.

The module’s generator can be equipped with a frequency converter located outside the housing. This allows you to use the generated electricity not only for domestic consumption, but also send it to an external network.

The heating unit may include an air compressor and a device for partial combustion and internal heating of the gas. Using this design of the heating unit allows you to provide internal, environmentally friendly, gas heating in the low pressure line and reduce energy loss for its heating.

The turbine may be made at least one stage and contain a partial nozzle apparatus. This design of the turbine allows you to configure the turbine at a given flow rate with a changing gas pressure in the high-pressure line and thereby ensure its effective operation in the entire pressure range used in GHG distribution systems.

Turbines of different modules can have nozzle devices of varying degrees of partiality. Setting the degree of partiality of different sizes in different nozzle devices allows for maximum efficiency of the turbine of each module.

It is possible to make turbine impellers made of composite material, for example, fiberglass. The use of composite material for the manufacture of turbine impellers can significantly reduce their mass, and therefore, reduce dynamic loads and forces on bearings, which increases the life of the unit.

It is possible to make module housings of composite material. The use of composite material for the manufacture of module housings allows for the same strength margins to significantly reduce wall thickness and, accordingly, reduce their weight and material consumption.

The present invention will be more clear after considering the following description of a gas turbine generator with reference to the attached diagram.

The gas turbine generator comprises a sealed housing 1 with covers 2 and 3, a turbine 4, an electric generator 5, bushing insulators 6, an inlet pipe 7 and an outlet pipe 8. The housing 1 has a through cavity 9 provided with an input and an output from opposite sides. The turbine 4 and the electric generator 5 are mechanically interconnected, for example, by a shaft and placed in the cavity 9 of the housing 1. The caps 2 and 3 are located respectively at the inlet and outlet of the cavity 9 of the housing 1. The inlet pipe 7 is located on the cover 2 of the entrance to the cavity 9 of the housing 1. Feedthrough insulators 6 are installed on the housing 1 and are electrically connected to the electric generator 5.

The gas turbine generator additionally includes a regulator 10, a valve 11, a heating unit 12. A turbine 4, an electric generator 5, a housing 1 with bushing 6, an outlet pipe 8 and a valve 11 are combined into a module 13. The gas turbine generator contains two modules 13, interconnected by the bodies 1 in series. The cover 2 of the entrance to the cavity 9 is installed on the housing 1 of the first module 13. The cover 3 of the exit from the cavity 9 is installed on the housing 1 of the last module 13 with the formation of the joint sealed cavity 9 of the modules 13. The controller 10 is installed on the inlet pipe 7, which is located on the cover 2 of the entrance in the cavity 9. Each valve 11 is mounted on the housing 1 of a separate module 13 through the outlet pipe 8. Behind the valve 11 of the last module 13, a heating unit 12 is connected in series.

The generator 5 of the module 13 may be equipped with a frequency converter 14 located outside the housing 1.

The heating unit 12 may include an air compressor 15 and a device 16 for partial combustion of gas.

The turbine 4 of the module 13 is made at least one-stage and contains a partial nozzle apparatus 17.

Turbines 4 of different modules 13 may have nozzle devices 17 with varying degrees of partiality.

The impellers 18 of the turbines 4 can be made of composite material, for example, fiberglass.

Housings 1 are made of composite material.

When installed in the piping system, the inlet pipe 7 of the first module 13 is connected through a regulator 10 to the high-pressure pipeline of natural gas. The outlet pipes 8 of the modules 13 through the taps 11 and the last module 13 through the valve 11 and the heating unit 12 are connected to the low-pressure pipeline of natural gas.

The gas turbine generator shown in the drawing, operates as follows.

Natural gas from the high-pressure line through the regulator 10 and the inlet pipe 7 is fed into the first module 13, sent through the nozzle apparatus 17 to the impeller 18 of the turbine 4, where the gas expands, its pressure and temperature decrease. Next, the gas flows around the body of the generator 5 and cools it. In this case, the turbine 4 generates mechanical energy, which is converted in the electric generator 5 into electricity transmitted through bushing insulators 6 to the electric network (not shown).

Further:

- if only one module 13 is required, then gas is supplied to the low pressure line through the outlet pipe 8 and the open valve 11 of this module (with the valve 11 of the second module closed);

- in another case, the gas is sent to the second module 13 (with the valve 11 of the first module closed), from where, through the outlet pipe 8 and the valve 11 of the second module 13, gas is supplied to the heating unit 12, where the steam generator is heated to provide the gas temperature of a given level and then enters to the low pressure line.

It is possible to supply electricity from the generator 5 to an external electrical network (not shown) through bushing insulators 6 and a frequency converter 14.

In the heating unit 12, the gas exiting from the valve 11 and the compressed air from the air compressor 15 enter the partial combustion and internal gas heating device 16, where a small part of the gas is burned, and the heat released during this process heats the entire mass of gas and the gas exiting the unit heating 12, has the desired temperature.

The feasibility of the proposed gas turbine generator is confirmed by a calculation study, with gas parameters:

pressure and temperature in the high-pressure line - P _in = 4 MPa and T _in = 280 K, respectively,

pressure and temperature in the low-pressure line - P _o = 1 MPa and T _o = 263 K, respectively.

The power of the generator of one module - N _1G = 600 kW and the rotational speed of the rotor of the generator - n = 3000 rpm are selected taking into account the fact that there is a pilot industrial sample of the generator with such parameters operating in a natural gas environment.

. Это вызвано тем, что числа Маха скоростей течения газа в каналах проточной части ступени при этом находятся еще на достаточно низком уровне (М_w≤0.5 - в рабочем колесе и М_C≤0.7 - в сопловом аппарате), что позволяет без ухудшения экономичности использовать более простую технологию изготовления лопаток турбины. При таких значениях величины степени понижения полного давления ступени

без больших потерь кпд при частоте вращения ротора турбины, равной заданной частоте вращения электрогенератора n=3000 об/мин, можно обеспечить диаметральный габарит турбины (наружный диаметр проточной части турбины D_T=0.62-0.65 м) близким диаметру промышленного электрогенератора мощностью 600 кВт, что позволяет минимизировать габарит и массу корпусов модулей.The degree of decrease in total pressure in the turbine stage is selected at the level

. This is because the Mach numbers of the gas flow rates in the channels of the flow part of the stage are still at a sufficiently low level (M _w ≤0.5 - in the impeller and M _C ≤0.7 - in the nozzle apparatus), which makes it possible to use more simple technology for making turbine blades. At such values of the degree of decrease in the total pressure of the stage

without large losses of efficiency at a rotational speed of the turbine rotor equal to a predetermined rotational speed of the generator n = 3000 rpm, it is possible to provide a diametrical dimension of the turbine (outer diameter of the turbine flow part D _T = 0.62-0.65 m) close to the diameter of an industrial electric generator with a power of 600 kW, which allows to minimize the overall size and weight of the module cases.

Full use of the available differential pressure of gas requires the use of four stages in series. For structural reasons, it is undesirable to have more than 2-3 stages on one shaft, therefore, for the adopted parameters, a two-module scheme was chosen in which the turbine of each module has two stages, while the gas flow through the turbine with an efficiency of 0.65 is G _T = 11 kg / s

The temperature of natural gas behind the first and second turbines is respectively equal to T _2T = 250 and 220 K. However, due to the short residence time in the turbine flow part (its length ~ 0.15 m), not exceeding 0.003-0.005 s, the flow part is iced up due to the presence of water vapor in natural gas does not occur.

To reduce the negative effect of gas leaks through the radial clearance on the efficiency and prevent its corresponding reduction, the nozzle units of the steps were made partial with a degree of partiality ε = 0.25 in the turbine of the first module and ε = 0.5 in the turbine of the second module; the angles of the impeller blades are so close in size that it is possible to produce impeller blades of all stages of a single profile; the same applies to nozzle apparatus profiles. This approach allows you to make the design of the turbines more technological and cheaper.

The use of a sealed housing design (the tightness of its internal cavity) can significantly simplify the design of the turbine due to the abandonment of the complex end-seal system on the shaft and / or the system of collection and useful use of gas leakage through the end seal.

Let us evaluate the efficiency of using the proposed design of a two-module gas turbine generator with a total capacity of 1200 kW.

On a standard type GDS with a pressure reducer, the gas temperature as a result of throttling decreases from T _in = 280 K to T _out = 265 K (i.e., above the lower permissible level of 263 K), as a result of which there is no need for gas heating.

и минимальное давление в магистрали низкого давления (сети потребителей) при P_вx=4 МПа должно быть не ниже Р_вых=2.6-2.8 МПа. Это значительно снижает номенклатуру ГРС, где прототип мог бы использоваться.In the prototype, the lower acceptable level of gas temperature is achieved at

and the minimum pressure in the low-pressure line (consumer network) at P _in = 4 MPa should not be lower than P _out = 2.6-2.8 MPa. This significantly reduces the range of GDS, where the prototype could be used.

In the inventive device, a capacity of 1 kg of natural gas compared to the prototype can be obtained about four times as much, but at the same time, the power N _K must be expended on the drive of the compressor 15 of the heating unit 12 and the heat energy Q from the combustion of part of the natural gas.

The required amount of heat for heating the gas with a flow rate of G _T = 11 kg / s from T = 220 K to T = 263 K at a pressure of P = 1 MPa is Q = 1055 kW. Heat to natural gas comes with compressed air leaving the compressor (Q _K = 170 kW) and from burnt natural gas (Q _G = 885 kW) with a flow rate of G _PG = 0.018 kg / s. To do this, you need to supply air with compressor 15 with a flow rate of G _B = 0.4 kg / s and pressure P _out = 1 MPa.

, температура воздуха в нем повышается от 288 К до 646 К (при кпд компрессора, равном 0.75), при этом потребляемая им мощность равна N_K=143 кВт.The compressor on the presented parameters has a degree of increase in total pressure

, the air temperature in it rises from 288 K to 646 K (with a compressor efficiency equal to 0.75), while the power consumed by it is N _K = 143 kW.

Thus, the external energy sources used to heat the gas are the compressor power N _K = 143 kW and the chemical energy of the burnt gas Q _G = 885 kW. Given that the ratio of the costs of thermal and mechanical energy is k≈0.3, the mechanical energy equivalent to the cost of the thermal energy spent on heating the gas will be N _P = Q _G · k = 885 · 0.3 = 265 kW. Then the “pure” power that a two-module installation can provide is:

N _eff = 2N _1G -N _P -N _K = 1200-265-143 = 792 kW.

If we carry out external gas heating using a heat exchanger with a coefficient of efficiency η = 60%, then the value of the effective power will be

those. less than with internal gas heating. It should also be noted that the gas-gas type heat exchanger used for external heating works at a high temperature of hot gas, which significantly reduces the life of its trouble-free operation.

It should also be noted the importance of sealing the cavity in which the turbines are located. So, the presence of GHG leak through the body seals to the outside in an amount of 0.5% of the gas flow through the turbine (G _UT = 55 g / s) will lead to the loss of the GHG chemical energy (converted into heat) by ΔQ = G _UT · N _u = 0.055 · 47300 = 2600 kJ / s, which is equivalent in cost to the loss of mechanical power by ΔN = ΔQ · k = 2600 · 0.3 = 780 kW. Consequently, a half-percent GHG leak leads to the fact that the value of the “clean” power of the installation becomes practically zero.

Thus, the objectives of the invention have been solved for the efficient use of potential GHG energy with high environmental performance and high reliability for the entire practically used differential pressure in high and low gas pressure lines.

Claims (7)

1. A gas turbine generator comprising a sealed enclosure with covers, a turbine, an electric generator, bushing insulators, an inlet and an outlet pipe, where the enclosure has a through cavity provided with inlet and outlet from opposite sides, the turbine and an electric generator are mechanically interconnected and placed in the cavity of the enclosure, cover located at the inlet and outlet of the cavity of the housing, and the inlet pipe is placed on the cover of the entrance to the cavity of the housing, bushing insulators are installed on the housing and connected to an electric generator, characterized in that the gas turbine generator further includes a regulator, a valve, a heating unit, the turbine, an electric generator, a housing with bushing insulators, an outlet pipe and a valve combined into a module, in addition, the gas turbine generator contains at least two modules connected in series with each other, where the cover the entrance to the cavity is installed on the housing of the first module, and the cover of the exit from the cavity is installed on the housing of the last module with the formation of a joint sealed cavity of the modules, and the controller is installed on m pipe, which is located on the lid of the entrance to the cavity, and each valve is mounted on the housing of a separate module through the output pipe, moreover, the heating unit is connected in series behind the valve of the last module. 2. The gas turbine generator according to claim 1, characterized in that the module generator is equipped with a frequency converter located outside the housing. 3. The gas turbine generator according to claim 1, characterized in that the heating unit comprises an air compressor and a device for partial combustion and internal gas heating. 4. The gas turbine generator according to claim 1, characterized in that the module turbine is made at least one-stage and contains a partial nozzle apparatus. 5. The gas turbine generator according to claim 4, characterized in that the turbines of different modules can have nozzle devices with varying degrees of partiality. 6. The gas turbine generator according to claim 1, characterized in that the turbine impellers are made of composite material, for example, fiberglass. 7. The gas turbine generator according to claim 1, characterized in that the housing is made of composite material, for example, fiberglass.