Horizontal steam generator

The utility model relates to a horizontal steam generator which comprises a combustion chamber, a heating chamber, a water inlet pipe, a steam exhaust pipe, an air inlet pipe and a preheating device.The heating chamber is arranged in the combustion chamber, a gap is reserved between the heating chamber and the combustion chamber, the preheating device is arranged at the top of the combustion chamber, one end of the water inlet pipe is communicated with the preheating device, and water enters the preheating device through the water inlet pipe to be preheated and then flows into the heating chamber. A plurality of first smoke exhaust pipes are arranged at the top of the combustion chamber, a second smoke exhaust pipe is arranged at the top of the preheating device, a steam exhaust opening is formed in the top of the heating chamber, one end of each steam exhaust pipe sequentially penetrates through the preheating device, the combustion chamber and the steam exhaust opening from top to bottom, and the other end